Part II: World and Consciousness
Empirical Findings Ia: World and Brain—Spatiotemporal Alignment and Perception
How is the brain related to the world? I will now show that spatiotemporal alignment does not only hold for the relationship between body and brain (i.e., body–brain relation), but also for the one between world and brain (i.e., world–brain relation). This, as I will show, is strongly supported by empirical data where the brain’s neural activity aligns itself to the temporal (and spatial) structure in the environment.
We are confronted with various types of stimuli in our environment that need to be encoded by our brain. For example, when we hear a music piece that is rhythmic, our brain seems to encode the rhythmic structure of the melody in such way that we are able to align ourselves to the melody. This allows us to participate in the melody’s rhythmic structure when, for instance, we swing our arms and legs while dancing. Our brain seems to sample the rhythmic structure of the tone sequence presented, which enables our participation in the rhythmic structure of the environmental events or objects (i.e., the music piece).
What kind of neuronal mechanisms mediate our brain’s apparent conforming and aligning to the rhythmic structure of environmental events? This was investigated experimentally in a recent study by Atteveldt et al. (2015). They presented background tones in either a rhythmic way (i.e., same time intervals between tones) or a random way (i.e., varying time intervals between tones). The rhythmic or random temporal structure of these tones served as background tones in blocks of 30 seconds: a 30 s block with rhythmic tones was followed by a 30 s block of random tones (interspersed by 15 s of baseline with no tones at all), which, in turn, was followed by a 30 s block of rhythmic tones and so on. These tones serving as background tones were combined with target tones (5–10 Hz slower frequency than the background tones) that were interspersed between the background tones; subjects had to detect the target tones and indicate that detection by button click. Subjects were investigated using fMRI with simultaneous EEG to combine both high spatial (fMRI) and temporal (EEG) accuracy.
What were their findings? Behaviorally, they observed significantly lower (i.e., faster) reaction times in response to target tones that were embedded in a rhythmic stream of tones when compared to those presented in the random sequence. Moreover, the hit, or detection, rate (i.e., the number of correctly detected tones) was significantly higher and thus more accurate in the rhythmic condition when compared to the random condition (see figure 2 in Atteveldt et al., 2015). This suggests that the temporal structure of the background condition has a significant impact on the perception and subsequent detection of the target tones: the background tones’ mode of presentation (rhythmic vs. random) impacted the detection (i.e., perception) and speed of motor reaction (i.e., reaction time) of the target tones.
Analogous results were obtained on the neuronal level. First, fMRI results showed the involvement of a distributed neural network with superior temporal gyrus (STG, which includes the auditory cortex), the insula, the medial frontal cortex, the thalamus, the brain stem, and the cerebellum when comparing the sound detection (rhythmic and random structure) with a no sound condition. When directly comparing the two sound conditions, higher signal responses were observed in bilateral STG in the random condition relative to the rhythmic condition (see figure 3 in Atteveldt et al., 2015).
Moreover, one could follow the sequence of the blocks in the dynamics of the STG signal: the response signal in STG showed a dynamic high–low pattern in that it was low during rhythmic blocks and high during random blocks (see figure 4 in Atteveldt et al., 2015). Finally, the degree of signal in right STG correlated positively with reaction times: the lower the response signal in right STG during all conditions (including both rhythmic and random), the faster the reaction times in response to the target tones.
Taken together, the behavioral results show that the rhythmic background condition led to faster reaction times in response to single stimuli when compared to the random background condition. However, contrary to expectation, that did not yield higher activity in, for instance, the STG. Instead, the opposite was observed, namely, lower activity changes in the STG during the rhythmic condition when compared to the random presentation. This was further underlined by the observed positive correlation between reaction time and STG activity.
Empirical Findings Ib: World and Brain—Spatiotemporal Alignment and Efficient Encoding
What about the EEG? The authors observed a particular waveform, N100, that is specific for the perception and subsequent detection of auditory tones as, for instance, the target tones in the present experimental paradigm. Interestingly, the amplitude of the N100 in response to the target tones was significantly lower in the rhythmic condition when compared to the target tones in the random condition (see figure 5 in Atteveldt et al., 2015). Moreover, the N100 was initiated earlier or faster (i.e., peak latency) in response to the target during the rhythmic condition relative to the random condition (see figures 6 and 7 in Atteveldt et al., 2015).
Taking both fMRI and EEG together, the results show that the brain seems to encode rhythmic and nonrhythmic (i.e., random) background stimuli sequences in the environment in different ways, which, in turn, impacts subsequent perception and detection of the target stimuli. Detection of target tones within rhythmic and random background tone sequences yielded differences on behavioral, and electrophysiological levels: the rhythmic condition showed more accurate and faster reaction times, decreased STG signals, and faster and lower N100 amplitude.
However, one may now be puzzled about the results. One would have expected higher activity in STG and N100 in the rhythmic condition because of the faster and more accurate reaction times. That was not the case though. Instead, the results showed the opposite, namely, that faster and more accurate reaction times went along with lower STG activity and N100 amplitude. This suggests, as the authors remark, a more efficient encoding of the rhythmic sequence (as indexed by faster and more accurate reaction times). However, what is meant by “efficient” encoding?
More efficient encoding means that less energy, and consequently less energy-based change by the brain’s spontaneous activity (as indexed by lower STG and N100 signals; see also ten Over et al., 2014, for behavioral support), is required to process the stimuli: the better the brain can align its spontaneous activity to the external stimuli (by integrating the latter within the former’s spatiotemporal structure), the more minimal the effort the brain has to expend in changing its ongoing spontaneous activity (such as its frequencies and amplitudes), the lower the degree of subsequent stimulus-induced activity (as in STG/fMRI and N100/EEG), and the faster the respectively associated behavior (i.e., the reaction times).
In contrast, the random stimulus sequence does not allow for such efficient encoding. There is no longer a rhythmic tone sequence in the environment to which the brain’s spontaneous activity can conform and thus align itself. In that case, the brain may need to recruit and expend a higher amount of energy and change in its ongoing spontaneous activity in order to process the external stimuli.
Taken altogether, the brain’s spontaneous activity seems to align itself to the temporal and ultimately to the spatiotemporal structure in its respective environmental context (i.e., the world). In the same way that the brain’s spontaneous activity aligns itself to the body, it also, analogously, aligns itself to the world. In both cases, body and world, the brain’s alignment is based on spatiotemporal ground, implying spatiotemporal alignment. The present data show that the brain’s spatiotemporal alignment to the world also impacts subsequent stimulus-induced activity in response to specific stimuli as well as the latter’s association with consciousness (i.e., perception).
Empirical Findings Ic: Rhythmic versus Continuous Modes of Brain Activity
Based on the findings described above and others, Schroeder and Lakatos (Lakatos et al., 2005, 2008, 2009; Schroeder et al., 2008; Schroeder & Lakatos 2009a,b, 2012; Schroeder et al., 2010) distinguish two different spatiotemporal modes of neural activity, that is, a rhythmic and a continuous mode. Let us start with the rhythmic mode.
In the case of a rhythmic mode, the brain’s slow-frequency fluctuations can align their phases with the probability distributions of the stimuli, that is, their predicted occurrence across different discrete points in (physical) time and space. The brain’s intrinsic activity can quasi follow what occurs in the environment. In such a “rhythmic mode” of neural operation, the fast-frequency oscillations during stimulus-induced activity are more or less aligned to the slow-frequency fluctuations and in turn the phases of these slow-frequency fluctuations are aligned to the statistical/likelihood structure of the stimuli in the environment (see also Canolty & Knight, 2010; Canolty et al., 2012; Klimesch et al., 2010; Sauseng & Klimesch, 2008, for excellent and critical reviews of such stimulus–phase coupling).
How can we describe the rhythmic mode of brain activity in more detail? There are two distinct processes in play. First, there is the cross-frequency coupling that allows for coupling and linking—that is, entraining—fast-frequency oscillations and even behavior to the phase of the ongoing slow-frequency oscillation in the spontaneous activity. And second, there is the coupling or alignment of the spontaneous activity’s slow-frequency oscillations and especially their phases to the onset of the rhythmic or statistical structure of the stimuli’s occurrence in the environment.
However, there are not always rhythmic stimuli in the environment that the brain and its intrinsic activity can align to. The rhythmic mode must therefore be distinguished from a more “continuous mode” of neural operation (Schroeder & Lakatos, 2009a,b). Unlike in the rhythmic mode, there seems to be no specific rhythm or statistical structure in the stimulus presentation to which the spontaneous activity’s slow-frequency oscillations (and subsequently the faster frequencies and behavior) can entrain and align their phase onsets. In other words, the brain is now “left to itself” and must therefore by itself actively structure and organize its own spontaneous activity.
How can the brain structure and organize its own spontaneous activity in such continuous mode? The brain can no longer rely on the rhythmic presentation of external stimuli and align itself to them but must become active itself, that is, continuously active. Instead of adapting the fast-frequency oscillations to the slower ones, as in the rhythmic mode, the stimulus-induced fast-frequency oscillations are now “on their own” in the continuous mode. The stimulus-induced fast-frequency oscillations must account for the stimulus independently of the resting-state activity’s slow-frequency oscillations and their phase onsets; that is so because the latter are no longer aligned to the statistical structure of the external stimuli. Rather than being helpful by aligning themselves to the extrinsic stimuli, as in the rhythmic mode, the spontaneous activity’s slow-frequency oscillations may now stand in the way of eliciting stimulus-induced fast-frequency oscillations.
Increase in the power of faster frequencies such as gamma may therefore be accompanied by their decreased cross-frequency coupling to slower frequencies’ phase onsets. This is exactly what has been observed in paradigms where there is no rhythmic presentation of stimuli (see above). The slow-frequency fluctuations (such as infraslow and delta) are consequently suppressed, while the fast-frequency fluctuations (such as gamma) are strengthened in order to process the external stimuli themselves independent of their respective temporal context in the environment. The temporal pattern in the continuous mode is thus reversed when compared to the one in the rhythmic mode, where the slow-frequency fluctuations are (relatively) stronger and the fast-frequency fluctuations remain (relatively) weak.
Empirical Findings IIa: World and Brain—Spatiotemporal Alignment and Social World
Recent neuroscience introduced the simultaneous scanning of two (or more) subjects’ neural activities during one and the same task. This procedure, called hyperscanning, allows researchers to investigate brain-to-brain coupling (Hasson et al., 2012), which entails neuronal and perceptual synchronization between different subjects (see Acquadro et al., 2015; Babiloni & Astolfi, 2015; Hasson & Frith, 2016; Koike et al., 2015; Schoot et al., 2016, for recent reviews). I here focus on one particular study that investigated how the playing of shared music by different players allows for their neuronal and perceptual synchronization (Lindenberger et al., 2009; Saenger et al., 2012).
Lindenberger et al. (2009) investigated, using EEG, eight pairs of guitarists playing one and the same melody together (sixty trials meaning sixty repetitions), a modern jazz fusion piece in E-minor with four quarters per measure. In each of the eight pairs of guitarists, they selected one lead guitarist with the respective other one following (before playing, the two guitarists were given a preparatory period during which they listened to a metronome and its beat). This served to test how much the one subject synchronizes her or his own playing and rhythm to those of the lead guitarist. That is possible only when the following subject’s perception of the guitar tones becomes synchronized with the playing and perception of the lead guitarist. The experimental design is thus based on the synchronization of the perceptions between two different subjects, the following and lead guitarist. This amounts to what I describe as “perceptual synchronization.”
Is the synchronization between the two subjects’ perceptions (e.g., perceptual synchronization) mediated by corresponding synchronization between their brains (e.g., neuronal synchronization)? For that, the investigators measured EEG in both subjects during their guitar playing. Using EEG, they determined thephase locking index (PLI); they measured the invariance of phases across different trials from single electrodes within one subject’s brain. This served to determine the degree of cortical synchronization between different electrodes within one particular brain related to one subject. More generally, this measures neuronal synchronization within the single brain.
In addition, they determined what they call interbrain phase coherence (IPC). The IPC measures the degree of constancy in phase differences across different trials in one and the same electrode from two different brains (of the two subjects in each pair) simultaneously. This served to determine the degree of cortical synchronization between different subjects’ brains in one particular electrode reflecting neuronal synchronization between different brains. Specifically, they time locked the periods around the onset of the metronome beat in the preparatory period and the play onset of the lead guitarists (3-s sequences with 1 s before onset and 2 s after). Based on prior considerations, they focused on lower and midrange frequencies up to 20 Hz.
What were the results? Let us start within the neuronal synchronization within brains. They observed an increase in phase synchronization between the different electrodes within each subject as indexed by the PLI. Such locking of the phase onsets between the different electrodes’ activities within the subjects’ brains was observed in especially fronto-central electrodes in the theta range (4–8 Hz) during both the onset of the metronome beats and the play onset of the lead guitarist. The task thus leads to increased cortical synchronization between the different electrodes within the subjects’ brains.
How about the neuronal synchronization between the different subjects’ brains? The increase in PLI in the brain of each subject was accompanied by an increase in IPC, the measure of the coherence of the phases between the brains of the two subjects. Especially the fronto-central electrodes showed increased phase coherence in a lower frequency, namely, the delta range (1–4 Hz) between the brains of the two subjects while they were playing the melody.
How are both intra- and intersubject measures of neural activity related to each other? Interestingly, intrasubject phase locking (PLI) and intersubject phase coherence (IPC) were positively correlated with each other: the higher the degree of intrasubject phase locking, the higher the degree of intersubject phase coherence. Both forms of neuronal synchronization, that is, within and between brains, are thus directly related and are apparently dependent upon each other.
Empirical Findings IIb: World and Brain—Spatiotemporal Alignment and Perceptual–Social Synchronization
How are the two forms of neuronal synchronization, for example, within and between brains, related to consciousness as, for instance, in perception of the different subjects—does neuronal synchronization entail perceptual synchronization? Lindenberger et al. (2009) observed that delta phase coherence in the following guitarists occurred in temporal relation to the play onset of the lead guitarist and her or his starting gesture immediately prior to play onset. The neuronal synchronization between the different subjects’ brains as indexed by delta phase coherence is thus related to the perceptual synchronization of the following guitarists to the lead guitarists. In short, neuronal synchronization within and between the subjects’ brains entails perceptual synchronization between subjects.
One may now want to argue that phase coherence between the different subjects’ brains can be traced back to the similarity of stimuli (the guitarists were playing the same piece) rather than their synchronization to each other. For that purpose, the same group conducted another study where they let the guitarist play different segments from the same piece, this time a classical piece, a rondo from an earlier composer (see Saenger et al., 2012). By letting the different guitarists play identical or different segments of the same piece, they could control for the similarity or identity of the stimuli and tasks. This allowed them to distinguish betweenstimulus-related effects and brain-related effects.
Stimulus-related effects concern those neural similarities between different subjects’ neural activities that can be traced back to the subjects’ exposure to the same stimuli. In contrast, brain-related effects refer to those neural similarities between different subjects’ neural activities that can be traced back to the brain itself—these effects reflect an active contribution from their brain’s spontaneous activity rather than the exposure to the same stimulus material (e.g., stimulus-induced activity).
The study by Saenger et al. (2012) controlled well for stimulus-related effects. They included thirty-two guitarists with sixteen overlapping duets and, using EEG, measured their neural activity while playing together. Unlike in the previous study by Lindenberger et al. (2009), they also manipulated the roles of both leader and follower across the sixteen pairs of guitarists. As in the previous study they measured PLI and IPC (and other whole brain measures such as small network organization, which I only peripherally touch on here).
They showed more or less the same results as in the previous study. There was again increased phase locking between electrodes (PLI) in the theta range in the brains of the single subjects during both preparatory and playing periods. Moreover, as in the previous study, such intrasubject phase locking was accompanied by interbrain phase coherence. There was phase coherence between the different subjects’ brains (IPC) in fronto-central electrodes with strong phase locking or coherence in especially the delta range. As in the previous study, this suggests that intersubject phase coherence occurs mainly in lower frequency ranges, namely, delta ranges, when compared to intrasubject phase locking in the theta range.
Importantly, the results show differences between leaders and followers in both measures, phase locking index (PLI) and inter brain phase coherence (IPC). The leader showed theta phase locking increase between electrodes, that is, PLI already in the preparatory period, while in the follower that increase occurred later in the playing period. Moreover, the delta phase coherence between subjects’ brains (i.e., the IPC) was particularly strong in the leader when compared to the followers.
These differences suggest that the followers synchronized their intra- and interneuronal phases (i.e., PLI and IPC) in relation to the leader and her or his phase onsets and coherence. Since the followers have no direct access to the leader’s brain, the former must have perceived the latter during the preparatory and initial playing period. Neuronal synchronization between the different subjects’ brains thus went along with perceptual synchronization of the followers to the leader. Accordingly, neuronal synchronization between brains is related to consciousness as it was accompanied by both conscious perception and action.
One may now be inclined to argue that the data presented above only concerned the social world but not the world as such. The data concerned only spatiotemporal alignment to another person as part of the social world and did not concern spatiotemporal alignment to other events or objects independent of persons. However, the same kind of spatiotemporal alignment with phase shifting, neuronal synchronization, and cross-frequency coupling has also been observed with regard to tones, and music (as shown here) as well as with respect to other objects and events (as demonstrated in various studies) (Nang et al., 2014; Schroeder & Lakatos, 2009, 2010; Stefanics et al., 2010). Hence, taken altogether, these data suggest that spatiotemporal alignment can be conceived of as a basic principle of how the brain’s neural activity aligns itself to the world in general, including both social and nonsocial worlds (see figure 8.1).
Figure 8.1 Temporal alignment of the brain to body and world.
Spatiotemporal Model Ia: Social Cognition and Consciousness—Attention Schema Theory (Graziano)
What do these findings tell us about consciousness? One may be inclined to suggest a core role for social perception and cognition in consciousness. The link between social cognition and consciousness has indeed been suggested by several authors (Carruthers, 2009; Frith, 1995; Saxe & Kanwisher, 2003; Saxe & Wexler, 2005; Saxe, 2006). I here discuss one of the most outstanding theories in this respect, the attention schema theory, as suggested by Graziano (Graziano, 2013; Graziano & Kastner, 2011; Webb & Graziano, 2015), that links social and cognitive functions.
According to the attention schema theory, consciousness is a perceptual model of attention directed toward either the external social world or one’s own inner world. More specifically, our brain processes various visual stimuli from the external social environment, all of which compete with each other. If, for instance, stimulus B wins, we will attend to stimulus B rather than stimulus A in the same way that we will attend to the person standing on the left rather than the one on the right. This amounts to pure attention, that is, social attention. Taken in this sense, attention is a feature or attribute of the stimulus itself. However, to be conscious of that very same stimulus, something else needs to be added. The attention schema theory suggests that this additional process consists in the reconstruction of the attention of a specific stimulus in terms of a model, a so-called attention schema.
The attention schema is a simplified model of the attention of stimulus A that leaves out many of the mechanistic details of the attentional process itself. Most importantly, the attention schema includes one’s own self (like the body) in reconstructing and modeling the attention of a specific stimulus: the model (i.e., the attention schema) includes stimulus, the attention itself of that stimulus, and one’s own self. Such model of the attention toward a specific stimulus provides us with consciousness of the attention to the stimulus—we then associate our attention to the stimulus with consciousness (which is used synonymously with the terms “subjective awareness” and “subjective experience”; see Webb & Graziano, 2015, p. 4).
How about the neural basis of consciousness in the context of the attention schema theory? Graziano suggests that regions like superior temporal sulcus, temporoparietal junction, and superior temporal gyrus as well as specific neurons like the mirror neurons provide the “machinery for social perception and attention” (Webb & Graziano, 2015, p. 4; see also Graziano & Kastner, 2011). By reconstructing the attention of other people to a specific stimulus using one’s own brain and its “machinery for social perception and attention,” one develops a model of another person’s attention. That, in turn, inclines us to attribute consciousness to the other person.
The same holds for one’s own inner mental states. We attend to our own inner states, such as thought Z. The very same neural basis, that is, “machinery for social perception and attention,” does then reconstruct a model of that attention to thought Z—we consequently attribute consciousness to ourselves. Hence, consciousness of both inner and outer events or objects can be traced to one and the same underlying neural basis, the “machinery for social perception and attention,” and processes, that is, the reconstruction of attention in terms of an attention schema.
One may now want to argue that consciousness in this sense is a second-order presentation of attention, which leads ultimately to theories that conceive consciousness in terms of higher-order cognitive functions such as higher-order thoughts (Lau & Rosenthal, 2011) or metacognition (Bayne & Owen, 2016; Carruthers, 2009). That is rejected, however, by Graziano and his assumption of a “machinery for social perception and attention.”
True indeed, the attention schema theory is based on a second-order representation of attention. However, unlike in cognitive approaches, that reconstruction is not cognitive, abstract, and semantic but rather sensory, perceptual, and concrete. The attention schema thus suggests a perceptual rather than a cognitive model of consciousness. Therefore, Graziano (Graziano & Kastner, 2011) compares it to Ned Block’s concept of phenomenal consciousness (as the property of consciousness itself) as distinguished from access consciousness (Block, 1996, p. 456)—the latter holds only if we access the attention schema cognitively by reporting it.
Spatiotemporal Model Ib: Spatiotemporal Alignment and Expansion versus Attention Schema and Social Extension
How do the attention schema theory and its determination of consciousness as a model of social attention (i.e., attention schema) stand in relation to the characterization of consciousness by spatiotemporal alignment and expansion?
Graziano supposes that attention comes with the stimulus and that we only need to reconstruct that very same attention. However, attention does not come solely and exclusively with the stimulus itself. Instead, as based on the various findings by Lakatos (Lakatos et al., 2008, 2013), it is also the degree to which we phase align our brain’s spontaneous activity to the stimulus and thus the degree of entrainment that first and foremost initiates and determines our attention. If we can phase align and thus entrain well, the stimulus will yield high degrees of attention from us; if, in contrast, phase shifting and entrainment are low, attention to the stimulus will be low too. The same can be said about the findings in the musicians discussed above (Lindenberger et al., 2009; Sänger, Müller, & Lindenberger, 2012): consciousness of and subsequently attention to the other musician may be driven here by brain–brain relationship (i.e., brain-to-brain coupling) as manifested in their degree of phase alignment and synchronization.
What does this imply for attention? Attention may be hybrid, resulting from the interaction between the brain’s spontaneous activity and the stimuli; that interaction, as phase entrainment and spatiotemporal alignment suggest, takes place on spatiotemporal rather than cognitive grounds. Hence, while Graziano may describe medium-order processes, he seems to neglect the most basic and fundamental lower-order processes ranging between world and brain, that is, spatiotemporal alignment processes, which first and foremost make possible consciousness and subsequently attention.
Moreover, by neglecting those basic and fundamental spatiotemporal processes between world and brain (i.e., world–brain relation), Graziano reverses the relationship between consciousness and attention: he seems to conceive attention as more basic than consciousness (see also Prinz, 2012) while the spatiotemporal model suggests the reverse, namely, that consciousness drives and is hence more basic than attention. I therefore conceive attention in primarily spatiotemporal terms rather than in either sensory, that is, perceptual, or cognitive terms; such spatiotemporal approach to attention needs to be further investigated and more clearly defined in the future.
More generally, Graziano neglects spatiotemporal expansion of the brain’s spontaneous activity beyond the brain itself to the world (i.e., spatiotemporal alignment). Because he neglects spatiotemporal alignment as the most basic and fundamental process, he cannot but conceive consciousness in terms of social perception and cognition. For that reason, he must revert to some medium-order perceptual and attentional processes to allow for accessing the other person and her or his consciousness. He consequently must assume expansion to social function rather than spatiotemporal features—one may therefore speak of social expansion that is primarily sensory and/or cognitive as distinguished from spatiotemporal expansion that is primarily spatiotemporal.
Note that I do not argue against social expansion per se. I am very happy to acknowledge social expansion and its relevance for consciousness as it is well supported by the musician study described above. Instead, I only argue against the assumption that social expansion is the basis and fundament for consciousness. As evidenced by the findings above, I suggest that social expansion is based on and can be traced to spatiotemporal features, that is, spatiotemporal alignment of the brain to the world. I consider such spatiotemporal alignment of the brain to the world as a necessary condition of possible consciousness (i.e., a prerequisite). Consciousness is consequently by default not only neuronal but, at the same time, ecological, that is, to be more precise, neuro-ecological.
Spatiotemporal Model IIa: Spatiotemporal Alignment versus Content-Based Integration
How can we conceptually describe spatiotemporal alignment in more detail? First and foremost, the data show that there is a direct relationship between world and brain. Their relationship is temporal and spatial: the brain aligns its spontaneous activity to the temporal and spatial features of its respective environmental context. Analogous to the case of the relation between body and brain, I therefore speak of spatiotemporal alignment of the brain to the world.
As in the case of body and brain, spatiotemporal alignment must be distinguished from other forms of their possible relationship. World and brain are also related in terms of sensorimotor, affective, cognitive, and social contents: the brain, as based on its respective functions, can integrate and generate sensorimotor, affective, cognitive, and social contents by means of which it can impact and modulate the world (see below for details). The relationship between world and brain is then determined by specific contents, that is, sensorimotor, affective, cognitive, or social. As these contents are based on integration, one can speak of content-based integration (see also chapter 7).
Spatiotemporal alignment must be distinguished from such content-based integration. Instead of integrating different contents (i.e., sensorimotor, affective, cognitive, and/or social), spatiotemporal alignment is based on the brain’s alignment to the world’s temporal and spatial features. This is clearly illustrated in our empirical examples: the brain aligns the temporal and spatial features of its own spontaneous activity to the temporal and spatial features of the world.
How are spatiotemporal alignment and content-based integration related to each other? I suppose that the former provides the background, if not the necessary condition, of the latter—content-based integration may be based on spatiotemporal alignment. The study by Lindenberger et al. (2009) provides some empirical evidence for that though indirectly: perception of the contents was dependent upon and thus modulated by the structure of the background tones (i.e., rhythmic or nonrhythmic), which induced different degrees of spatiotemporal alignment.
Yet another difference between spatiotemporal alignment and content-based integration is the location of their operation. Spatiotemporal alignment operates across the boundaries of world and brain—it crosses them in temporal and spatial terms. In contrast, content-based integration is restricted to and thus located within the confines of the brain. Note, however, that spatiotemporal alignment does not take place outside the brain. Instead, spatiotemporal alignment constitutes a continuum between world and brain, a continuum between ecological and neuronal spatiotemporal features. One can therefore speak of a neuro-ecological continuum.
Spatiotemporal Model IIb: Neuro-ecological Continuum between World and Brain
What do I mean by the concept of neuro-ecological continuum? The concept of neuro-ecological continuum is first and foremost an empirical term—it describes the empirical relationship between the brain’s neuronal activity and the world’s ecological activity. Moreover, that very same continuum is based on spatiotemporal features rather than specific contents, that is, sensorimotor, cognitive, affective, social—the neuro-ecological continuum is first and foremost a spatiotemporal continuum between world and brain.
The empirical and spatiotemporal nature of the neuro-ecological continuum implies that it comes in degrees: it is not a matter of all-or-nothing but can rather exhibit different degrees in the spatiotemporal continuum. Thereby the relation between world and brain, including their respective spatiotemporal features, is dynamic and bidirectional. The neuro-ecological continuum can either shift more strongly toward the brain’s neural activity at the expense of the world’s ecological activity—this amounts to what Schroeder and Lakatos describe as a “continuous mode of brain activity.” Or, alternatively, the neuro-ecological continuum can shift more toward the opposite pole, the world, which occurs at the expense of the brain’s neuronal activity—this amounts to what Schroeder and Lakatos describe as a “rhythmic mode of brain activity.”
Taken in this sense, the neuro-ecological continuum allows for a vast range of various spatiotemporally based constellations between neuronal and ecological activities in brain and world. The healthy brain and its neural activity are usually balanced, more or less, in their relation to the world—they can thus be located around the middle of the neuro-ecological continuum. This is different in psychiatric disorders where the brain’s neuro-ecological balance is shifted toward the extreme neuronal and ecological poles of brain and world (see figures 8.2a and 8.2b).
Figure 8.2a Brain between body and world.
Figure 8.2b Neuro-ecological continuum and world–brain relation.
For instance, behavioral autism can be characterized by almost complete detachment from the world as reflected in the subjects’ social isolation and disinterest in others. Such behavior can be traced to their brains’ neural activity that is primarily neuronally rather than neuro-ecologically determined—this shifts neuronal activity toward the neuronal pole of the brain and away from the ecological (and social) pole of the world on the neuro-ecological continuum (Damiano et al., submitted).
Analogous though somewhat different detachment from the world can be observed in schizophrenia. These patients often show social isolation and thus autistic behavior. Neuronally, their brain is no longer able to align the phase onsets of their spontaneous activity to the onsets of external stimuli (Lakatos et al., 2013), which can interfere with their ability to couple and align to the spatiotemporal structure of the world (Northoff & Duncan, 2016). The opposite seems to be the case in mania, where patients show extremely strong behavior directed toward the external world (they are quasi “glued” to various stimuli in the external world). Their brains’ neuronal activity is shifted toward the ecological pole of the neuro-ecological continuum (Martino et al., 2016; Northoff et al., 2017).
The neuro-ecological continuum may thus describe the balance between world and brain in both neural activity and associated behavior. As that balance can be characterized by temporal–spatial features, that is, spatiotemporal alignment of the brain to the world, one may characterize the balance by spatiotemporal structure and organization. This amounts to what I described as the “form” of consciousness, the spatiotemporal organization and structure of consciousness (Northoff, 2013, 2014b). The concept “form” of consciousness refers thus to a third dimension that complements the contents and level/state as other dimensions of consciousness (chapter 7).
Spatiotemporal Model IIc: Relation between World and Brain—World–Brain Relation
The neuro-ecological continuum is characterized by the balance between neuronal and ecological features in the brain’s neural activity. Therefore, the brain’s neural activity can be described as hybrid in that it is neither purely neuronal nor purely ecological. On a more general level, the hybrid neuro-ecological nature of the brain’s neural activity means that it relates world and brain—this amounts to what I call the world–brain relation.
What do I mean by world–brain relation? First, the concept of world–brain relation is here understood in an empirical sense. It denotes the relation between world and brain that is constituted by the brain’s spatiotemporal alignment in its interaction with the world. This is empirically exemplified by the example of the perceptual–social synchronization between the musicians (Lindenberger et al., 2009; Sänger et al., 2012) that, neuronally, can be traced to specific neuronal mechanisms such as phase coherence and so forth (see above).
Note that, in addition to this empirical sense, the concept of world–brain relation can also be understood in an ontological sense. Rather than concerning specific empirical mechanisms such as spatiotemporal alignment, the concept of world–brain relation does then refer to existence and reality. As will become clear in chapter 9, I will characterize the brain’s existence and reality by world–brain relation.
Second, the concept of world–brain relation, as understood in an empirical sense in this chapter in the following, describes bilateral or mutual interaction between world and brain. The brain must show the capacity or predisposition to exert and recruit certain neuronal mechanisms such as spatiotemporal alignment that allow it to align its neural activity to the stochastic structure of the world. More generally, the brain must be predisposed for developing a possible rhythmic mode of neural activity as distinguished from a continuous mode (see above).
At the same time, the world itself must show a certain spatiotemporal structure (see chapter 3 for more detail on that point) to which the brain and its neural activity can possibly align. If, for instance, the musicians do not play any kind of rhythmic structure, spatiotemporal alignment of the single musician’s brain to the other musicians’ brains would remain impossible. Accordingly, in addition to the brain’s predisposition for the rhythmic mode, the world itself must predispose possible spatiotemporal alignment by the brain. Therefore, I characterize the concept of world–brain relation by bilateral interaction between both brain and world.
Third, the characterization of world–brain relation by bilateral interaction shifts the conceptual focus from world and brain themselves to the concept of relation. The concept of world–brain relation denotes specifically the relation between world and brain rather than world and brain themselves independent of their relation. When I speak of world–brain relation in both empirical (here in this chapter) and ontological (chapters 9–11) contexts, my focus is on this relation rather than world and brain themselves. Specifically, the relation between world and brain adds something that cannot be reduced to either world or brain: their relation makes it possible to integrate, that is, nest and contain, world and brain in a commonly shared spatiotemporal framework, that is, relational time and space (chapter 9).
Spatiotemporal Model IIIa: World–Brain Relation—Spatiotemporal Nestedness of Brain within World
How can we describe the relation between world and brain (i.e., world–brain relation) in more detail? The world–brain relation is primarily spatiotemporal. The different spatiotemporal scales or ranges of world and brain are linked and integrated in their relation. Specifically, the smaller spatiotemporal scale or range of the brain is aligned and thus related to the much larger one of the world: the former (i.e., the brain) is thereby nested within the latter (i.e., the world). We can therefore describe the world–brain relation as spatiotemporal nestedness. In the same way that, in a set of Russian nesting dolls, the smaller doll is nested within the next larger one, the brain is nested within the world.
How are different (i.e., larger and smaller) spatiotemporal scales related to each other? We saw in the case of the brain’s spontaneous activity that, purely empirically, the phase of slower frequencies is coupled to and thus contains or nests the amplitude of faster frequencies—this is described as cross-frequency coupling (chapter 7). Taking the different frequencies together results in an elaborate temporal structure where slower frequencies contain or nest the next faster one and so on—one can thus speak of a slow–fast nestedness or, better, spatiotemporal nestedness, which indicates a certain directedness, that is, from slow to fast, in the brain’s spontaneous activity.
I now assume an analogous slow–fast nestedness with spatiotemporal nestedness in the relation between world and brain. The world includes much slower frequencies, such as seismic earth waves, than does the brain. Therefore, those slower frequencies nest and contain the brain’s faster frequencies—taken in purely spatiotemporal terms, the brain is thus nested and contained within the world. For that reason, I speak of world–brain relation rather than brain–world relation (see below for details).
Note that we already encountered the concept of spatiotemporal nestedness in the previous chapter: it described how the smaller spatiotemporal scale or range of single stimuli or tasks is integrated, that is, nested, within the relatively larger spatiotemporal scale or range of the brain’s spontaneous activity. Taken in this sense, spatiotemporal nestedness must be understood in a purely neuronal sense as confined to the boundaries of the brain.
I here extend the use of the same concept beyond the boundaries of the brain to the brain’s relationship with the world. Spatiotemporal nestedness is now no longer purely neuronal but neuro-ecological, referring to the neuro-ecological continuum between world and brain. That very same neuro-ecological continuum consists in the degree to which different spatiotemporal scales or ranges are linked and integrated and thus nested within each other: the better the brain’s smaller spatiotemporal scale is integrated and thus nested within the much larger one of the world, the more continuous the neuro-ecological continuum.
Spatiotemporal Model IIIb: World–Brain Relation—Triple Spatiotemporal Expansion of the Brain’s Neural Activity
Taken in such neuro-ecological sense, spatiotemporal nestedness operates across the boundaries of brain and world including their respective spatiotemporal scales. The brain and its neural activity thus expand beyond their own boundaries to the world when aligning to and including the world’s much larger spatiotemporal scale or range. I therefore speak of the spatiotemporal expansion of the brain to the world. Such spatiotemporal expansion can be understood in a threefold way.
First, spatiotemporal expansion described how the brain’s spontaneous activity expands the single stimulus or task beyond their own spatiotemporal scales, that is, the duration and extension of stimulus or task (chapters 2, 5, and 7). This can be described empirically as a rest–stimulus interaction and can, conceptually, be phrased as rest–stimulus relation (chapters 2 and 7).
Second, I described how the body and its spatiotemporal scale expand the brain’s spontaneous activity beyond itself to the body. That was made possible by what I described empirically as spatiotemporal alignment of brain to body, which conceptually was phrased as body–brain relation. Third, we now encounter the expansion of the brain’s spontaneous activity by its spatiotemporal alignment to the world. This is empirically accounted for by the brain’s spatiotemporal alignment to the world, which conceptually is phrased as world–brain relation.
Taken altogether, one can speak of triple spatiotemporal expansion: the brain’s stimulus-induced activity is expanded by the brain’s spontaneous activity (first expansion), which, in turn, is itself expanded by its spatiotemporal alignment to body (second expansion) and world (third expansion). Such triple spatiotemporal expansion allows for spatiotemporal nestedness between brain, body, and world: the brain’s stimulus-induced activity is spatiotemporally nested within the brain’s spontaneous activity, which itself is spatiotemporally nested within body and world (i.e., world–brain relation).
Spatiotemporal Model IIIc: World–Brain Relation—Triple Spatiotemporal Expansion and Consciousness
Why is the triple spatiotemporal expansion of the brain relevant for consciousness? The data presented in this (and the previous) chapter show that the degree to which the brain’s spontaneous activity is nested within body and world strongly impacts consciousness. The better and the higher the degree to which the brain’s spontaneous activity is spatiotemporally aligned to the spatiotemporal structure of body and world, the more likely the respective stimulus or content can be associated with consciousness.
I consider spatiotemporal alignment of the brain to the world and subsequently the triple spatiotemporal expansion a necessary condition of consciousness, that is, a neural prerequisite of consciousness. Without the spatiotemporal alignment of our brain’s spontaneous activity to body and world, we can no longer associate consciousness to the stimuli and their contents. This is supported by the above presented data. Moreover, it is in line with the data on the loss of consciousness where such spatiotemporal alignment is disrupted (chapter 4). Once the brain and its spontaneous activity are no longer expanded beyond themselves to body and world and thus spatiotemporally nested within the latter, consciousness becomes impossible—this is the case in disorders of consciousness (chapter 4).
Taken on a more conceptual level, this implies that world–brain relation (and body–brain relation) is a necessary condition of possible consciousness (i.e., a predisposition). Loss of world–brain relation entails the loss of consciousness. Note that I explicitly focus on the relation between world and brain. Both world and brain may still be present even during the absence of consciousness. Instead, it is the presence of specifically their relation, the world–brain relation, that is central for the possible presence of consciousness.
Accordingly, the absence of the relation between world and brain leads to the absence of consciousness even if both world and brain remain present. Therefore, it is the relation itself, that is, the relation between world and brain, rather than world and brain themselves, that is, independent of their relation, that makes possible consciousness—the world–brain relation. This is what I mean when I say that the world–brain relation is a necessary condition of possible consciousness—the world–brain relation is thus what I describe as a “predisposition of consciousness.”
Note that, as already indicated above, the concept of relation can be understood in both empirical and ontological senses. Throughout this chapter I understand the concept of relation in an empirical sense as characterized by specific empirical mechanisms such as spatiotemporal alignment of the brain to the world, while later (in chapters 9–11), I will shift from the empirical to the ontological realm. Ontologically, the concept of relation in world–brain relation denotes existence and reality, that is, a basic unit of existence and reality as suggested in structural realism. More specifically, I will suggest that the world–brain relation accounts for the existence and reality of the brain (chapter 9), which, in turn, renders possible (i.e., predisposes) the existence and reality of consciousness (chapter 10).
Spatiotemporal Model IIId: World–Brain Relation—Brain–World Relation?
Given the bilateral nature of their interaction, one may now wonder why I speak of world–brain relation rather than brain–world relation. After all, it is the brain that aligns to the world—this would make the case for the reverse concept, namely, brain–world relation. That is to neglect the difference in spatiotemporal scale or range between world and brain though. The brain shows a much smaller spatiotemporal range than the world, which is much larger and thus includes a wider range (such as ultrasonic frequencies and the aforementioned extremely slow frequencies of seismic earth waves). The concept of world–brain relation thus spans across and integrates different spatiotemporal scales. However, that by itself is not yet a reason to prefer the concept of world–brain relation over that of brain–world relation.
I characterized world–brain relation by spatiotemporal nestedness and expansion. Both imply directionality (i.e., spatiotemporal directionality). Faster frequencies are nested within slower ones, which allows expanding the former by the latter. Hence, slower frequencies must be predisposed to allow for nesting and expanding of faster frequencies: without slower frequencies, spatiotemporal nestedness and expansion remain impossible. An analogous spatiotemporal directionality can now be observed in the relation between world and brain: the world shows slower frequencies and thereby makes possible the faster frequencies of the brain—the brain is thus nested and contained within the world (i.e., world–brain relation).
To characterize the spatiotemporal relation between world and brain by the concept of brain–world relation would be to simply reverse spatiotemporal directionality: the faster frequencies of the brain would then contain or nest the slower frequencies of the world. True, the concept of brain–world relation is certainly conceivable on purely conceptual–logical grounds. However, brain–world relation with reverse spatiotemporal directedness (i.e., nesting of slower within faster frequencies) is not supported on empirical grounds, that is, it remains empirically implausible. Therefore, conceived in purely spatiotemporal terms, I deem the concept of world–brain relation to be more empirically plausible than brain–world relation.
In addition to their empirical plausibility, the concepts of world–brain relation and brain–world relation can also be characterized by different roles for consciousness and cognition. I claim that world–brain relation is a necessary empirical (this chapter) and ontological (chapter 10) condition of possible consciousness—world–brain relation is both a neural and ontological predisposition of consciousness. Accordingly, put in a nutshell, I deem world–brain relation including its spatiotemporal characterization as essential for consciousness in both an empirical and an ontological regard.
In contrast, I do not suppose analogous relevance of brain–world relation for consciousness. Rather than predisposing consciousness, brain–world relation is central for sensory, motor, cognitive, affective, and social function with subsequent brain-based perception and cognition of the world. Without elaborating the details here, I therefore deem brain–world relation to predispose cognition rather than consciousness. To now replace world–brain relation by brain–world relation is to confuse consciousness and cognition.
As already discussed previously (chapters 3 and 6), consciousness cannot be traced or reduced to specific contents and our cognition of those very same contents. This is further supported by the fact that consciousness itself cannot be reduced to or fully explained by cognitive functions such as attention, working memory, or higher-order cognitive functions (Lau & Rosenthal, 2011; Prinz, 2012; Tsuchiya et al., 2012). While these various cognitive functions may well account for the cognitive component of consciousness, that is, reporting with access to the contents of consciousness (chapter 7), they do not account for the phenomenal features of consciousness as targeted here (chapter 7). Taken in the present context, I suppose that brain–world relation can well account for the cognitive features of consciousness while world–brain relation is necessary for the phenomenal features of consciousness.
Spatiotemporal Model IVa: Four E’s—Embodiment and Body–Brain Relation
There is much conceptual (i.e., philosophical) discussion about the role of body and world in consciousness—this can be characterized by the four E’s, embodiment, enactment, extendedness, and embeddedness. Without going into thorough detail, I will discuss the four E’s briefly in the present spatiotemporal context.
Let us start with embodiment. The advocate of the body and embodiment may now wonder about the role of the body. After all, the brain is part of the body and the body “locates” us in the world. One would consequently assume a more central role for the body than the world in consciousness. This conforms well to what is described as embodiment (Gallagher, 2005; Rowland, 2010) and enactment (Noe, 2004; Rowland, 2010) in the current philosophical discussion.
How does the spatiotemporal model account for the seemingly special role of the body? We saw above that there is no principal difference between body and world when it comes to spatiotemporal alignment, nestedness, and expansion. In both cases, one and the same mechanism, that is, spatiotemporal alignment, allows spatiotemporal expansion of the brain beyond itself to body and world with the result that the brain is nested within both. This suggests no special role of the body when compared to the world.
However, there is a difference in degree. The body is continuously present and therefore presents a much more stable and continuous presence for the brain’s spatiotemporal alignment. The world, in contrast, is much more unstable and not as continuously present—the degree of the brain’s spatiotemporal alignment to the body may therefore be much stronger than its alignment to the world. Moreover, the world includes a much larger spatiotemporal range than the body, which differs much more from the spatiotemporal range of the brain—the larger spatiotemporal discrepancy may make it more difficult for the brain to align itself to the world than to the body. Therefore, it is only in exceptional cases (as, for instance, in extreme forms of meditation when one detaches one’s own cognition and ultimately one’s own body from their alignment to the brain’s neural activity; see Tang et al., 2015; Tang & Northoff, 2017) that the brain’s spatiotemporal alignment to the world may override its spatiotemporal alignment to the body.
Accordingly, the spatiotemporal model acknowledges the difference between body and world. However, that difference between body and world is merely quantitative and thus empirical. There is a difference in the degree of spatiotemporal alignment of the brain to body and world. The spatiotemporal model thus considers the body to be only quantitatively and thus empirically different from the world. In contrast, there is no qualitative and ultimately ontological difference between world and body in general and with regard to consciousness in particular (see chapters 10 and 11 for more details on the ontological issue).
This carries major implications for the relation between the concepts of body–brain relation and world–brain relation. I subsume the concept of body–brain relation under the umbrella of the more basic and fundamental concept of world–brain relation: the body is part of the world for the brain and its spatiotemporal alignment with subsequent spatiotemporal nestedness and expansion. Hence, the concept of world–brain relation, as understood here, includes that of body–brain relation. The concept of embodiment as specified by body–brain relation can consequently be subsumed under the umbrella of the concept of world–brain relation.
Spatiotemporal Model IVb: Four E’s—Embeddedness and Spatiotemporal Scaffolding
One may now wonder how the concept of spatiotemporal expansion stands in relation to those of extendedness, embeddedness, and enactment as used in current philosophical discussion (Clark, 1997, 2008; Clark & Chalmers, 2010; Gallagher, 2005; Lakoff & Johnson, 1999; Noe, 2004; Rowland, 2010; Shapiro, 2014; Thompson, 2007; Varela et al., 1991). Specifically, one may want to argue that what I mean by “spatiotemporal expansion” is much better expressed and covered by the concepts of embeddedness, extendedness, and enactment; for that reason, I had better use the latter rather than my own concept. I will show that both are quite compatible and that the concepts of embeddedness, extendedness, and enactment need to be specified in spatiotemporal terms.
How about the concept of embeddedness? The concept of embeddedness points out that consciousness and cognition are dependent upon the respective situational constellation. Certain events or objects in the environment can be used as resources for consciousness to minimize the load for the brain—the world thus provides an “external scaffolding” for consciousness (Shapiro, 2014). Presupposing external scaffolding, embeddedness implies that consciousness can be understood in a relational sense—it allows for relation between internal states and external events or objects.
The spatiotemporal model supposes that such scaffolding is possible on spatiotemporal grounds. The world and its various objects or events provide a certain spatiotemporal structure as in the case of music. Our empirical example (Lindenberger et al., 2009; Sänger et al., 2012) demonstrated that the brain’s spontaneous activity can align itself to the rhythmic structure of music in spatiotemporal terms. That, in turn, makes it possible to relate and thus scaffold the brain’s internal state to the external events or objects in the world (i.e., the music piece).
I consequently specify the concept of scaffolding as spatiotemporal scaffolding. The concept of spatiotemporal scaffolding means that the spatiotemporal features of the world are those features to which the brain can align, which, in turn, makes it possible to use the world and its various objects and events for external scaffolding. Spatiotemporal scaffolding is possible only when there is some relation between world and brain (i.e., world–brain relation). Without spatiotemporal alignment of the brain to the world, the world and its various objects or events, any kind of external scaffolding remains impossible. Therefore, I consider world–brain relation as based on spatiotemporal alignment as a necessary condition of external scaffolding in terms of spatiotemporal scaffolding and ultimately of embeddedness.
Spatiotemporal Model IVc: Four E’s—Extendedness/Enactment and Spatiotemporal Expansion
The concept of spatiotemporal expansion is also quite compatible with the concepts of extendedness and extended mind (Clark, 2008; Clark & Chalmers, 2010). For example, consciousness can well extend to external contents beyond one’s own internal contents. For instance, the piano and its keys may become part of the body in the consciousness of the professional pianist. The same occurs when we listen to music with its rhythms’ becoming part of our consciousness. Consciousness is thus distributed and social rather than being nondistributed or focalized and merely neuronal.
How is such extendedness possible? Our empirical example of the guitarists showed such extendedness: the single musician and her or his playing was extended beyond that musician and her or his brain to the other musician and her or his brain (Lindenberger et al., 2009; Sänger et al., 2012). This was made possible by spatiotemporal alignment of the one brain’s spontaneous activity to the other person’s brain. Due to spatiotemporal alignment and expansion of the brain’s spontaneous activity to the world including other persons and their brains, consciousness becomes distributed and social just as described in the concept of extendedness.
Taken in this sense, consciousness is extended and thus distributed and social by default: spatiotemporal alignment and expansion with world–brain relation are a necessary condition of possible consciousness without which the latter becomes impossible. Extendedness of consciousness is thus not an accidental secondary feature of consciousness but a necessary and most basic feature as it is based on world–brain relation. Hence, the spatiotemporal model of consciousness is not only quite compatible with extendedness but makes the latter even stronger by showing its necessity for possible consciousness on both empirical and conceptual grounds. Spatiotemporal expansion of the brain to the world and thus extendedness must be considered necessary conditions of possible consciousness (i.e., they are a predisposition of consciousness).
The central importance of the world is also pointed out in the concept of enactment (Noe, 2004; Thompson, 2007; Varela et al., 1991). Beyond the body, the world itself is here taken into account in constituting consciousness. Specifically, it is the way in which we relate to and thereby enact the world in our actions and perception that first and foremost makes possible sense and ultimately consciousness. By enacting the world, we transform the world into our environment, the “life world,” as some say (Merleau-Ponty, 1963, p. 235).
How does the concept of enactment stand in relation to the spatiotemporal model of consciousness? The proponent of enactment is right. We and our brains are enacting the world. However, such enacting should not be understood in a literal sense, that is, in terms of action and perception. Instead, enacting may better be understood in a spatiotemporal sense: our brain aligns itself to the spatiotemporal structure in the world by means of which it constitutes a neuro-ecological continuum that, in turn, makes possible consciousness that allows us to subsequently perceive and act in that very same world.
It may therefore be better to speak of spatiotemporalizing rather than enacting: by aligning itself to the world in a spatiotemporal way, the brain links and integrates the spatiotemporal features of the world to itself and our body, which, in turn, makes it possible to enact the world. Hence, the brain spatiotemporalizes the world (Northoff, 2014a) for us by linking and integrating the world’s spatiotemporal features to our brain’s neuronal activity and its own spatiotemporal features. Therefore, I consider spatiotemporal alignment a necessary condition of possible enactment.
Spatiotemporal Model IVd: Four E’s—Concept of World and Argument of Inclusion
One may now be interested to know what exactly I mean by the concept of world. Besides other meanings, one can understand the term “world” in an empirical, phenomenological, and ontological sense. The empirical concept of world consists in the world as we observe it—that world is presupposed in empirical investigation as in neuroscience. The world understood in a phenomenological sense is the world as we experience it in consciousness—this is the world referred to in phenomenology. Finally, the concept of world can also be understood in an ontological sense in terms of its existence and reality as it remains independent of us including our brains.
The concept of world, as understood in this section, demarcates the border between empirical and ontological realms. It goes beyond the purely observational and thus empirical sense in that it conceives the world by itself independent of our observation. That wider meaning is, for instance, reflected in my use of the term ecological that includes both social and nonsocial features. Such concept of world reaches out toward the ontological meaning of world, that is, its existence and reality by itself independent of us. That will be fully discussed in chapters 10 and 11.
In contrast, the concept of world, as understood here, does not amount to the phenomenological meaning of world, that is, the way we experience the world in our consciousness. That would be to confuse the necessary condition of possible consciousness with the phenomenal features of consciousness itself: the world–brain relation is a necessary condition of possible consciousness, which precludes its characterization by consciousness itself. Therefore, the concept of world as in world–brain relation is not meant in a phenomenological sense as, for instance, used in phenomenology. I refer the reader to chapter 11 as well as chapters 12–14 for a more detailed account of the concept of world.
We are now ready to address the second part of the argument of inclusion, that is, the need to include the world in our model of consciousness. The argument of inclusion, we recall, points out the need to include both body and world in our model of consciousness. The spatiotemporal model can well include the world, giving it a central role in consciousness—that role of the world for consciousness is much stronger than in most other accounts, including both neuroscientific and philosophical ones. Rather than just including the world as an additional modulatory factor (i.e., as context or external scaffold), the spatiotemporal model supposes that the world in terms of its relation to the brain, the world–brain relation, is a necessary condition of possible consciousness.
How can we support the assumption that the world in terms of world–brain relation is a necessary condition of possible consciousness (i.e., a predisposition)? The data presented here show that that holds in an empirical way: spatiotemporal alignment of the brain’s neural activity to the world and thus its neuro-ecological continuum is an NPC (Northoff, 2013, 2014b; Northoff & Heiss, 2015). The same holds, analogously, on the ontological level where the world–brain relation can be regarded an ontological predisposition (of the possible existence and reality) of consciousness (chapter 10).
Finally, the spatiotemporal model can account not only for the inclusion of body and world but also for their close and intimate relationship in consciousness. By assuming a similar mechanism (i.e., spatiotemporal alignment) in body–brain relation and world–brain relation, brain, body, and world are integrated and intimately linked with each other. That very same intimate linkage is well reflected in spatiotemporal nestedness that includes and operates across all three, brain, body, and world.