Editing Binding problem (section)

== Consciousness and binding ==
=== Summary of problem ===
[[John Raymond Smythies|Smythies]]<ref name="Smythies 1994">{{Cite book|last1 = Smythies|first1 = John R. (John Raymond)|title = The walls of Plato's cave : the science and philosophy of (brain, consciousness, and perception|year = 1994|publisher = Avebury|location = Aldershot; Brookfield, USA|isbn = 978-1-85628-882-8|oclc = 30156912}}</ref> defines the combination problem, also known as the subjective unity of perception, as "How do the brain mechanisms actually construct the phenomenal object?". Revonsuo<ref name="Revonsuo 1999"/> equates this to "[[consciousness]]-related binding", emphasizing the entailment of a phenomenal aspect. As Revonsuo explores in 2006,<ref>Revonsuo, A, (2006) Inner Presence: Consciousness as a biological phenomenon. Cambridge, MA: MIT Press.</ref> there are nuances of difference beyond the basic BP1:BP2 division. Smythies speaks of constructing a phenomenal object ("local unity" for Revonsuo) but philosophers such as [[René Descartes]], [[Gottfried Wilhelm Leibniz]], [[Immanuel Kant]], and James (see Brook and Raymont)<ref>The Unity of Consciousness. Stanford Encyclopaedia of Philosophy. http://plato.stanford.edu/entries/consciousness-unity/</ref> have typically been concerned with the broader unity of a phenomenal experience ("global unity" for Revonsuo) – which, as Bayne<ref name="Bayne">Bayne, T. and Chalmers, D. (2003) What is the unity of consciousness? In Cleeremans, A. ''The Unity of consciousness, Binding, Integration and Dissociation'', Oxford University Press.</ref> illustrates may involve features as diverse as seeing a book, hearing a tune and feeling an emotion. Further discussion will focus on this more general problem of how sensory data that may have been segregated into, for instance, "blue square" and "yellow circle" are to be re-combined into a single phenomenal experience of a blue square next to a yellow circle, plus all other features of their context. There is a wide range of views on just how real this "unity" is, but the existence of medical conditions in which it appears to be subjectively impaired, or at least restricted, suggests that it is not entirely illusory<!--[26]-->.<ref>{{Cite journal|last1=Parra|first1=Mario A.|last2=Abrahams|first2=Sharon|last3=Logie|first3=Robert H.|last4=Méndez|first4=Luis G.|last5=Lopera|first5=Francisco|last6=Della Sala|first6=Sergio|date=2010-09-01|title=Visual short-term memory binding deficits in familial Alzheimer's disease|journal=Brain|volume=133|issue=9|pages=2702–2713|doi=10.1093/brain/awq148|pmid=20624814|issn=0006-8950|doi-access=free|hdl=20.500.11820/20fdff3b-6b93-478a-bd74-dfc81dc43ae3|hdl-access=free}}</ref>

There are many neurobiological theories about the subjective unity of perception. Different visual features such as color, size, shape, and motion are computed by largely distinct neural circuits but we experience this as an integrated whole. The different visual features interact with each other in various ways. For example, shape discrimination of objects is strongly affected by orientation but only slightly affected by object size.<ref>{{Cite journal|last1=Norman|first1=J. Farley|last2=Swindle|first2=Jessica M.|last3=Jennings|first3=L. RaShae|last4=Mullins|first4=Elizabeth M.|last5=Beers|first5=Amanda M.|date=June 2009|title=Stereoscopic shape discrimination is well preserved across changes in object size|journal=Acta Psychologica|volume=131|issue=2|pages=129–135|doi=10.1016/j.actpsy.2009.03.009|issn=1873-6297|pmid=19389660}}</ref> Some theories suggest that global perception of the integrated whole involves higher order visual areas.<ref name=":0">{{Cite journal|last1=Stoll|first1=Susanne|last2=Finlayson|first2=Nonie J.|last3=Schwarzkopf|first3=D. Samuel|date=2020-10-15|title=Topographic signatures of global object perception in human visual cortex|journal=NeuroImage|volume=220|pages=116926|doi=10.1016/j.neuroimage.2020.116926|issn=1053-8119|pmc=7573540|pmid=32442640}}</ref> There is also evidence that the posterior parietal cortex is responsible for perceptual scene segmentation and organization.<ref name=":1">{{Cite journal|last1=Grassi|first1=Pablo R.|last2=Zaretskaya|first2=Natalia|last3=Bartels|first3=Andreas|date=2018-08-08|title=A Generic Mechanism for Perceptual Organization in the Parietal Cortex|journal=The Journal of Neuroscience|volume=38|issue=32|pages=7158–7169|doi=10.1523/JNEUROSCI.0436-18.2018|issn=1529-2401|pmc=6596091|pmid=30006362}}</ref> Bodies facing each other are processed as a single unit and there is increased coupling of the extrastriate body area (EBA) and the posterior superior temporal sulcus (pSTS) when bodies are facing each other.<ref>{{Cite journal|last1=Bellot|first1=Emmanuelle|last2=Abassi|first2=Etienne|last3=Papeo|first3=Liuba|date=2021-03-31|title=Moving Toward versus Away from Another: How Body Motion Direction Changes the Representation of Bodies and Actions in the Visual Cortex|journal=Cerebral Cortex|volume=31|issue=5|pages=2670–2685|doi=10.1093/cercor/bhaa382|issn=1460-2199|pmid=33401307}}</ref> This suggests that the brain is biased towards grouping humans in twos or dyads.<ref name=":2">{{Cite journal|last=Papeo|first=Liuba|date=November 2020|title=Twos in human visual perception|journal=Cortex; A Journal Devoted to the Study of the Nervous System and Behavior|volume=132|pages=473–478|doi=10.1016/j.cortex.2020.06.005|issn=1973-8102|pmid=32698947|s2cid=220074584|url=https://osf.io/yuxza/}}</ref>

The boundary problem is another unsolved problem in neuroscience and phenomenology that is related to the binding problem. The boundary problem is essentially the inverse of the binding problem, and asks how binding stops occurring and what prevents other neurological phenomena from being included in first-person perspectives, giving first-person perspectives hard boundaries. Topological segmentation and electromagnetic field topology have been proposed as possible avenues for solving the boundary problem as well as the binding problem.<ref>{{cite journal |last1=Gómez-Emilsson |first1=Andrés |last2=Percy |first2=Chris |date=3 August 2023 |title=Don't forget the boundary problem! How EM field topology can address the overlooked cousin to the binding problem for consciousness |journal=Front Hum Neurosci |volume= 17|issue= |pages= |doi=10.3389/fnhum.2023.1233119 |doi-access=free |pmid=37600559 |pmc=10435742 }}</ref>

=== History ===
Early philosophers René Descartes and Gottfried Wilhelm Leibniz<!--[26]--><ref>{{Citation|last1=Kulstad|first1=Mark|title=Leibniz's Philosophy of Mind|date=2020|url=https://plato.stanford.edu/archives/win2020/entries/leibniz-mind/|encyclopedia=The Stanford Encyclopedia of Philosophy|editor-last=Zalta|editor-first=Edward N.|edition=Winter 2020|publisher=Metaphysics Research Lab, Stanford University|access-date=2022-06-09|last2=Carlin|first2=Laurence}}</ref> noted that the apparent unity of our experience is an all-or-none qualitative characteristic that does not appear to have an equivalent in the known quantitative features, like proximity or cohesion, of composite matter. [[William James]],<ref>{{cite book|url=https://archive.org/details/in.ernet.dli.2015.210224|title=The principles of psychology Vol. I|last=James|first=William|date=1890-01-01|page=145|publisher=New York : Holt}}</ref> in the nineteenth century, considered the ways the unity of consciousness might be explained by known physics and found no satisfactory answer. He coined the term "combination problem", in the specific context of a "mind-dust theory" in which it is proposed that a full human conscious experience is built up from proto- or micro-experiences in the way that matter is built up from atoms. James claimed that such a theory was incoherent, since no causal physical account could be given of how distributed proto-experiences would "combine". He favoured instead a concept of "co-consciousness" in which there is one "experience of A, B and C" rather than combined experiences. A detailed discussion of subsequent philosophical positions is given by Brook and Raymont (see 26). However, these do not generally include physical interpretations.

[[Alfred North Whitehead|Whitehead]]<ref>Whitehead, A. N. (1929) Process and Reality. 1979 corrected edition, edited by David Ray Griffin and Donald W. Sherburne, Free Press. {{ISBN|0-02-934570-7}}</ref> proposed a fundamental ontological basis for a relation consistent with James's idea of co-consciousness, in which many causal elements are co-available or "compresent" in a single event or "occasion" that constitutes a unified experience. Whitehead did not give physical specifics, but the idea of compresence is framed in terms of causal convergence in a local interaction consistent with physics. Where Whitehead goes beyond anything formally recognized in physics is in the "chunking" of causal relations into complex but discrete "occasions". Even if such occasions can be defined, Whitehead's approach still leaves James's difficulty with finding a site, or sites, of causal convergence that would make neurobiological sense for "co-consciousness". Sites of signal convergence do clearly exist throughout the brain but there is a concern to avoid re-inventing what [[Daniel Dennett]]<ref name="Dennett">{{cite book|last =Dennett|first= Daniel|date=1981|title =  Brainstorms: Philosophical Essays on Mind and Psychology|publisher = MIT Press|isbn = 0262540371|url = https://books.google.com/books?id=_xwObaAZEwoC}}</ref> calls a Cartesian Theater or a single central site of convergence of the form that Descartes proposed.

Descartes's central "soul" is now rejected because neural activity closely correlated with conscious perception is widely distributed throughout the cortex. The remaining choices appear to be either separate involvement of multiple distributed causally convergent events or a model that does not tie a phenomenal experience to any specific local physical event but rather to some overall "functional" capacity. Whichever interpretation is taken, as Revonsuo<ref name="Revonsuo 1999"/> indicates, there is no consensus on what structural level we are dealing with – whether the cellular level, that of cellular groups as "nodes", "complexes" or "assemblies" or that of widely distributed networks. There is probably only general agreement that it is not the level of the whole brain, since there is evidence that signals in certain primary sensory areas, such as the V1 region of the visual cortex (in addition to motor areas and cerebellum), do not contribute directly to phenomenal experience.

=== Experimental work on the biological basis of binding ===
==== fMRI work ====
Stoll and colleagues conducted an fMRI experiment to see whether participants would view a dynamic bistable stimulus globally or locally.<ref name=":0" /> Responses in lower visual cortical regions were suppressed when participants viewed the stimulus globally. However, if global perception was without shape grouping, higher cortical regions were suppressed. This experiment shows that higher order cortex is important in perceptual grouping.

Grassi and colleagues used three different motion stimuli to investigate scene segmentation or how meaningful entities are grouped together and separated from other entities in a scene.<ref name=":1" /> Across all stimuli, scene segmentation was associated with increased activity in the posterior parietal cortex and decreased activity in lower visual areas. This suggests that the posterior parietal cortex is important for viewing an integrated whole.

==== EEG work ====
Mersad and colleagues used an EEG frequency tagging technique to differentiate between brain activity for the integrated whole object and brain activity for parts of the object.<ref>{{Cite journal|last1=Mersad|first1=Karima|last2=Caristan|first2=Céline|date=2021-09-17|title=Blending into the Crowd: Electrophysiological Evidence of Gestalt Perception of a Human Dyad|journal=Neuropsychologia|volume=160|pages=107967|doi=10.1016/j.neuropsychologia.2021.107967|issn=1873-3514|pmid=34303717|s2cid=236183221|doi-access=free}}</ref> The results showed that the visual system binds two humans in close proximity as part of an integrated whole. These results are consistent with evolutionary theories that face-to-face bodies are one of the earliest representations of social interaction.<ref name=":2" /> It also supports other experimental work showing that body-selective visual areas respond more strongly to facing bodies.<ref>{{Cite journal|last1=Abassi|first1=Etienne|last2=Papeo|first2=Liuba|date=2020-01-22|title=The Representation of Two-Body Shapes in the Human Visual Cortex|journal=The Journal of Neuroscience|volume=40|issue=4|pages=852–863|doi=10.1523/JNEUROSCI.1378-19.2019|issn=1529-2401|pmc=6975292|pmid=31801812}}</ref>

==== Electron tunneling ====
Experiments have shown that ferritin and neuromelanin in fixed human ''substantia nigra pars compacta'' (SNc) tissue are able to support widespread electron tunneling.<ref>{{Cite journal|last=Rourk|first=Christopher J.|date=May 2019|title=Indication of quantum mechanical electron transport in human substantia nigra tissue from conductive atomic force microscopy analysis|url=http://dx.doi.org/10.1016/j.biosystems.2019.02.003|journal=Biosystems|volume=179|pages=30–38|doi=10.1016/j.biosystems.2019.02.003|pmid=30826349|bibcode=2019BiSys.179...30R|s2cid=73509918|issn=0303-2647|url-access=subscription}}</ref> Further experiments have shown that ferritin structures similar to ones found in SNc tissue are able to conduct electrons over distances as great as 80 microns, and that they behave in accordance with Coulomb blockade theory to perform a switching or routing function.<ref>{{Cite journal|last1=Rourk|first1=Christopher|last2=Huang|first2=Yunbo|last3=Chen|first3=Minjing|last4=Shen|first4=Cai|date=2021-08-12|title=Indication of Strongly Correlated Electron Transport and Mott Insulator in Disordered Multilayer Ferritin Structures (DMFS)|journal=Materials|volume=14|issue=16|pages=4527|doi=10.3390/ma14164527|pmid=34443050|pmc=8399281|bibcode=2021Mate...14.4527R|issn=1996-1944|doi-access=free}}</ref><ref>{{Cite journal|last1=Labra-Muñoz|first1=Jacqueline A.|last2=de Reuver|first2=Arie|last3=Koeleman|first3=Friso|last4=Huber|first4=Martina|last5=van der Zant|first5=Herre S. J.|date=2022-05-15|title=Ferritin-Based Single-Electron Devices|journal=Biomolecules|volume=12|issue=5|pages=705|doi=10.3390/biom12050705|pmid=35625632|pmc=9138424|issn=2218-273X|doi-access=free}}</ref> Both of these observations are consistent with earlier predictions that are part of a hypothesis that ferritin and neuromelanin can provide a binding mechanism associated with an action selection mechanism,<ref>{{Cite journal|last=Rourk|first=Christopher John|date=September 2018|title=Ferritin and neuromelanin "quantum dot" array structures in dopamine neurons of the substantia nigra pars compacta and norepinephrine neurons of the locus coeruleus|journal=Biosystems|volume=171|pages=48–58|doi=10.1016/j.biosystems.2018.07.008|pmid=30048795|s2cid=51722018|issn=0303-2647|doi-access=free|bibcode=2018BiSys.171...48R}}</ref> although the hypothesis itself has not yet been directly investigated. The hypothesis and these observations have been applied to [[Integrated Information Theory]].<ref>{{Cite journal|last=Rourk|first=Chris|date=2022-01-06|title=Application of the Catecholaminergic Neuron Electron Transport (CNET) Physical Substrate for Consciousness and Action Selection to Integrated Information Theory|journal=Entropy|volume=24|issue=1|pages=91|doi=10.3390/e24010091|pmid=35052119|pmc=8774445|bibcode=2022Entrp..24...91R|issn=1099-4300|doi-access=free}}</ref>

=== Modern theories ===
Daniel Dennett<ref name="Dennett"/> has proposed that we, as humans, sensing our experiences as individual single events is illusory and that, instead, at any one time there are "multiple drafts" of sensory patterns at multiple sites. Each would only cover a fragment of what we think we experience. Arguably, Dennett is claiming that consciousness is not unified and there is no phenomenal binding problem. Most philosophers have difficulty with this position (see Bayne),<ref name="Bayne" /> but some physiologists agree with it. In particular, the demonstration of [[perceptual asynchrony]] in psychophysical experiments by Moutoussis and Zeki,<ref>{{Cite journal|last1=Moutoussis|first1=K.|last2=Zeki|first2=S.|date=1997-03-22|title=A direct demonstration of perceptual asynchrony in vision|journal=Proceedings of the Royal Society of London. Series B: Biological Sciences|volume=264|issue=1380|pages=393–399|doi=10.1098/rspb.1997.0056|pmc=1688275|pmid=9107055}}</ref><ref>{{Cite journal|last1=Moutoussis|first1=K.|last2=Zeki|first2=S.|date=1997-10-22|title=Functional segregation and temporal hierarchy of the visual perceptive systems|journal=Proceedings of the Royal Society of London. Series B: Biological Sciences|volume=264|issue=1387|pages=1407–1414|doi=10.1098/rspb.1997.0196|pmc=1688701|pmid=9364780}}</ref> where color is perceived before orientation of lines and before motion by 40 and 80 ms respectively, constitutes an argument that, over these very short time periods, different attributes are consciously perceived at different times, leading to the view that at least over these brief periods of time after visual stimulation, different events are not bound to each other, leading to the view of a disunity of consciousness,<ref>{{Cite journal|last=Zeki|first=S.|date=May 2003|title=The disunity of consciousness|journal=Trends in Cognitive Sciences|volume=7|issue=5|pages=214–218|doi=10.1016/s1364-6613(03)00081-0|pmid=12757823|s2cid=19365977|issn=1364-6613}}</ref> at least over these brief time intervals.  Dennett's view might be in keeping with evidence from recall experiments and change blindness purporting to show that our experiences are much less rich than we sense them to be – what has been called the Grand Illusion.<ref>{{cite journal|last1 = Blackmore|first1 = S. J.|last2 = Brelstaff|first2 = G.|last3 = Nelson|first3 = K.|last4 = Troscianko|first4 = T.|year = 1995|title = Is the richness of our visual world an illusion? Transsaccadic memory for complex scenes|journal = Perception|volume = 24|issue = 9|pages = 1075–81|doi = 10.1068/p241075|pmid = 8552459|s2cid = 28031132}}</ref> However, few, if any, other authors suggest the existence of multiple partial "drafts". Moreover, also on the basis of recall experiments, Lamme<ref name="Lamme">{{cite journal|last1 = Lamme|first1 = V|year = 2002|title = The grand Grand Illusion illusion|journal = Journal of Consciousness Studies|volume = 9|pages = 141–157}}</ref> has challenged the idea that richness is illusory, emphasizing that phenomenal content cannot be equated with content to which there is cognitive access.

Dennett does not tie drafts to biophysical events. Multiple sites of causal convergence are invoked in specific biophysical terms by Edwards<ref>{{cite journal|last1 = Edwards|first1 = J. C.|year = 2005|title = Is consciousness only a property of individual cells?|url = http://www.ucl.ac.uk/jonathan-edwards|journal = Journal of Consciousness Studies|volume = 12|pages = 60–76}}</ref> and Sevush.<ref>{{cite journal|last1 = Sevush|first1 = S|year = 2006|title = Single neuron theory of consciousness|journal = Journal of Theoretical Biology|volume = 238|issue = 3|pages = 704–725|doi = 10.1016/j.jtbi.2005.06.018|pmid = 16083912|bibcode = 2006JThBi.238..704S}}</ref> In this view the sensory signals to be combined in phenomenal experience are available, in full, at each of multiple sites. To avoid non-causal combination, each site/event is placed within an individual neuronal dendritic tree. The advantage is that "compresence" is invoked just where convergence occurs neuro-anatomically. The disadvantage, as for Dennett, is the counter-intuitive concept of multiple "copies" of experience. The precise nature of an experiential event or "occasion", even if local, also remains uncertain.

The majority of theoretical frameworks for the unified richness of phenomenal experience adhere to the intuitive idea that experience exists as a single copy, and draw on "functional" descriptions of distributed networks of cells. Baars<ref>Baars, B. J. (1997), In the Theater of Consciousness New York, Oxford University Press.</ref> has suggested that certain signals, encoding what we experience, enter a "Global Workspace" within which they are "broadcast" to many sites in the cortex for parallel processing. Dehaene, Changeux and colleagues<ref>{{cite journal|last1 = Dehaene|first1 = S.|last2 = Sergent|first2 = C.|last3 = Changeux|first3 = J.-P.|year = 2003|title = A neuronal network model linking subjective reports and objective physiological data during conscious perception|journal = Proceedings of the National Academy of Sciences|volume = 100|issue = 14|pages = 8520–8525|doi = 10.1073/pnas.1332574100|pmid = 12829797|pmc = 166261|bibcode = 2003PNAS..100.8520D|doi-access = free}}</ref> have developed a detailed neuro-anatomical version of such a workspace. Tononi and colleagues<ref>{{cite journal|last1 = Balduzzi|first1 = D|last2 = Tononi|first2 = G|year = 2008|title = Integrated information in discrete dynamical systems: motivation and theoretical framework|journal = PLOS Comput Biol|volume = 4|issue = 6|page = e1000091|doi = 10.1371/journal.pcbi.1000091|pmid = 18551165|pmc = 2386970|bibcode = 2008PLSCB...4E0091B|doi-access = free}}</ref> have suggested that the level of richness of an experience is determined by the narrowest information interface "bottleneck" in the largest sub-network or "complex" that acts as an integrated functional unit. Lamme<ref name="Lamme"/> has suggested that networks supporting reciprocal signaling rather than those merely involved in feed-forward signaling support experience. Edelman and colleagues have also emphasized the importance of re-entrant signaling<!--[16]-->.<ref>{{Cite journal|last=Edelman|first=Gerald M.|date=1993-02-01|title=Neural Darwinism: Selection and reentrant signaling in higher brain function|journal=Neuron|language=en|volume=10|issue=2|pages=115–125|doi=10.1016/0896-6273(93)90304-A|pmid=8094962|s2cid=8001773|issn=0896-6273}}</ref> Cleeremans<ref>{{cite journal|last1 = Cleeremans|first1 = A|year = 2011|title = The radical plasticity thesis|journal = Frontiers in Psychology|volume = 2|page = 86|doi = 10.3389/fpsyg.2011.00086|pmid = 21687455|pmc = 3110382|doi-access = free}}</ref> emphasizes meta-representation as the functional signature of signals contributing to consciousness.

In general, such network-based theories are not explicitly theories of how consciousness is unified, or "bound", but rather theories of functional domains within which signals contribute to unified conscious experience. A concern about functional domains is what Rosenberg<ref>Rosenberg, G. (2004) A Place for Consciousness. Oxford, Oxford University Press. {{ISBN|0-19-516814-3}}.</ref> has called the boundary problem; it is hard to find a unique account of what is to be included and what excluded. Nevertheless, this is, if anything is, the consensus approach.

Within the network context, a role for synchrony has been invoked as a solution to the phenomenal binding problem as well as the computational one. In his book, [[The Astonishing Hypothesis]],<ref>Crick, F. (1995) The Astonishing Hypothesis. Scribner Paperback {{ISBN|0-684-80158-2}} {{ISBN|978-0684801582}}</ref> Crick appears to be offering a solution to BP2 as much as BP1. Even von der Malsburg,<!--[19]--><ref>{{Cite journal|last1=von der Malsburg|first1=Ch.|last2=Schneider|first2=W.|date=1986-05-01|title=A neural cocktail-party processor|journal=Biological Cybernetics|language=en|volume=54|issue=1|pages=29–40|doi=10.1007/BF00337113|pmid=3719028|s2cid=25195155|issn=1432-0770}}</ref> introduces detailed computational arguments about object feature binding with remarks about a "psychological moment". The Singer group<!--[14]--><ref>{{Cite journal|last=Singer|first=Wolf|date=2006-01-25|title=Consciousness and the Binding Problem|url=https://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2001.tb05712.x|journal=Annals of the New York Academy of Sciences|language=en|volume=929|issue=1|pages=123–146|doi=10.1111/j.1749-6632.2001.tb05712.x|pmid=11349422|s2cid=3174911|url-access=subscription}}</ref> also appear to be interested as much in the role of synchrony in phenomenal awareness as in computational segregation.

The apparent incompatibility of using synchrony to both segregate and unify might be explained by sequential roles. However, Merker<ref name="Merker 2013"/> points out what appears to be a contradiction in attempts to solve the subjective unity of perception in terms of a functional (effectively meaning computational) rather than a local biophysical domain in the context of synchrony.

Functional arguments for a role for synchrony are in fact underpinned by analysis of local biophysical events. However, Merker<ref name="Merker 2013"/> points out that the explanatory work is done by the downstream integration of synchronized signals in post-synaptic neurons: "It is, however, by no means clear what is to be understood by 'binding by synchrony' other than the threshold advantage conferred by synchrony at, and only at, sites of axonal convergence onto single dendritic trees..." In other words, although synchrony is proposed as a way of explaining binding on a distributed rather than a convergent basis, the justification rests on what happens at convergence. Signals for two features are proposed as bound by synchrony because synchrony effects downstream convergent interaction. Any theory of phenomenal binding based on this sort of computational function would seem to follow the same principle. The phenomenality would entail convergence, if the computational function does.

The assumption in many of the quoted models suggest that computational and phenomenal events, at least at some point in the sequence of events, parallel each other in some way. The difficulty remains in identifying what that way might be. Merker's<ref name="Merker 2013"/> analysis suggests that either (1) both computational and phenomenal aspects of binding are determined by convergence of signals on neuronal dendritic trees, or (2) that our intuitive ideas about the need for "binding" in a "holding together" sense in both computational and phenomenal contexts are misconceived. We may be looking for something extra that is not needed. Merker, for instance, argues that the homotopic connectivity of sensory pathways does the necessary work.