Neural binding
A paper addressing this idea states, "Thus, correlated activity was only obtained when cells responded to different aspects of the same 'Gestalt'".
Other studies using EEGs from the human scalp also examined gamma wave activity, showing how stimuli seemed to be in accordance with preattentive binding.
Instead, Chen uses the idea that perception depends on "topological invariants that describe the geometrical potentiality of the entire stimulus configuration".
[6] A decade later Francis Crick & Christof Koch developed the model further by explaining the synchronization of distant neurons by transient gamma wave oscillations being guided by attention.
Modern models that are currently being developed often retain the structure of temporal synchrony due to this significant advantage as well as the strong experimental support for the existence of global brain oscillations.
It has been widely observed that distributed collections of neurons oscillate within the gamma band of frequencies (typically between 30–80 Hz).. Varela’s model describes the selection of cellular assemblies, sometimes referred to as resonant or reverberating (Lorente de Nó) circuits, as being integrated into a larger ensemble by transient spike phase locking.
This addresses the explanatory difficulty of the simultaneous nature of binding because it allows many signals to be in transit in parallel within an overlapping frequency range without interference.
In 2001, da Rocha developed a model which utilized the basic structure of the Temporal Binding Hypothesis, with global phase synchronization being a primary mechanism of distributing information, but emphasized the importance of a quantum computation performed on a local level.
[10][11][12] The hypothesis is based in part on the observation by many independent researchers that electron tunneling occurs in ferritin (an iron storage protein that is prevalent in those neurons) at room temperature and ambient conditions.
[17][18][19] The hypothesis also predicted that disordered ferritin arrays like those found in SNc tissue should be capable of supporting long-range electron transport and providing a switching or routing function, both of which have been subsequently observed.
[23][24] However, a team led by Dr. Pascal Kaiser of Harvard Medical School subsequently demonstrated that those neurons code movement, consistent with the earlier predictions of CNET.
[25] While the CNET mechanism has not yet been directly observed, it may be possible to do so using quantum dot fluorophores tagged to ferritin or other analytical techniques for detecting electron tunneling.
These models can be vulnerable to the combinatorial and connectivity problems, which come as a natural consequence of depending solely on one-to-one communication of conventional information via spike rate coding.
These models also require the seamless directing and combining of signals, which either assumes a controller (proposed to be the pulvinar nuclei[27]) or a mechanism for the spontaneous self-assembly of neural ensembles.
Such coherent responses point to the fact that the brain is doing a kind of coding where it is piecing certain neurons together in the works of making the form of an object.
Since the brain is putting these segmented pieces together unsupervised, a significant consonance is found with many philosophers (like Sigmund Freud) who theorize an underlying subconscious that helps to form every aspect of our conscious thought processes.
It is not proven whether the dorsal thalamus is the primary organizer, but it does fit the specific profile for collecting neuronal activity and rapidly coordinating between what is happening in the brain and outside of it.
The space in and around the dorsal thalamus, the thalomocortical area, is able to generate fast voltage-dependent membrane potential oscillations which allow it to react quickly to received messages.
[28] Francis Crick and Christof Koch proposed that specific neural activity can stimulate short-term memory, forming a continuous and dynamic consciousness.
Certain observations have even led these scientists to hypothesize that since there is little cognition going on during REM sleep, the increased thalamocortical responses show the action of processing in the waking preconscious.
Streaming and building of episodic memories would not be possible if neural binding did not unconsciously connect the two synchronous oscillations.
Relational bindings, or relationships between separate objects, concepts, and memories, are very flexible because the targets can be combined in so many different ways to deal with the present situation, and the hippocampus ensures that these parts are arranged into a coherent whole.
According to Opitz, this is viable because the hippocampus meets all criteria to be suitable for the regulation relational binding and, based on its patterns of activity, it is likely that it is involved.
Researchers have suggested that these issues with coherence of neural networks give rise to the hallmark autistic symptoms, namely, impaired social cognition/interactions and repetitive behaviors.
It is also possible that disordered binding between the regulatory mechanisms of the brain gives rise to a lack of synchronized activation of its neural networks.
A deeper understanding of the mechanisms underlying consciousness on the biochemical level has practical implications which extend to the development of more effective and reliable anesthetics.
