These are excerpts and elaborations from my book "The Nature of Consciousness"
Consciousness As
Self-Reference The idea of some form of
"self-referential feedback" (of some kind of loop inside the brain)
is firmly rooted in modern space-based binding theories. Gerald Edelman's "reentrant maps" and Nicholas Humphrey's "sensory reverberating feedback loop" are variations on
the same theme. The idea is that, somehow, the brain refers to itself, and this
self-referentiality, somehow, unchains
consciousness. Rather than
"space-based", these theories tend to be "process-based",
since they are not only looking for the place where the binding occurs but also
for the way it occurs, and the process turns out to be much more important than
the place. According to Edelman, consciousness is a natural development of the ability to build
perceptual categories (such as “blue”, “tall”, “bird”, “tree”, “book”), the
process that we normally call generalization.
The brain can do this because neurons get organized by experience in
maps, each neural map dealing with a feature of perceptions (color, shape,
etc.). First of all, Edelman distinguishes between primary
consciousness (imagery and sensations, basically being aware of things in the
world) and higher-order consciousness (language and self-awareness). For primary consciousness to
appear a few requirements must be met. It takes a memory, and an active type of
memory, that does not simply store new information but also continuously
reorganizes (or “re-categorizes”) old information. Then it takes the ability to learn, but learning is not only
memorizing, it is also a way to rank stimuli, to assign “value” to stimuli, to
value one experience over another. A new value will typically result in a new
behavior, and that is what learning is about. Then it takes the ability to make
the distinction between the self from the rest of the world, i.e. a way to
represent what is part of the organism and what is not. Then it takes a way to
represent chronology, to order events in time. Finally, it takes a maze of
“global reentrant pathways” (i.e., forms of neural transmission that let
signals travel simultaneously in both directions) connecting all these
anatomical structures. Primary consciousness arises from "reentrant
loops" that interconnect "perceptual categorization" and
"value-laden" memory ("instincts"). In general, cognitive
functions emerge from reentrant processes.
Consciousness therefore
arises from the interaction of two parts of the neural system that differ
radically in their anatomical structure, evolution, organization and function:
the one responsible for categorizing (external stimuli) and the other
responsible for "instinctive" behavior (i.e., homeostatic control of
behavior). Consciousness emerges as the product of an ongoing categorical
comparison of the workings of those two kinds of nervous system. From an evolutionary point
of view, the milestone moment was when a link emerged between category and
value, between those two different areas of the brain. That is when the basis
for consciousness was laid. A higher-level consciousness
(being aware of itself), probably unique to humans, is possible if the brain is
also capable of abstracting the relationship between the self and the non-self,
and this can only happen through social interaction, and this leads naturally
to the development of linguistic faculties. Edelman identifies the regions that are
assigned to define self within a species (the amygdala, the hippocampus, the
hypothalamus) and those that operate to define the non-self (the cortex, the
thalamus and the cerebellum). Note that, according to
Edelman, concept-formation preceded language. Language was enabled by
anatomical changes. What changed with the advent of language is that concepts
became independent of time, i.e. permanent.
And semantics preceded syntax: acquiring phonological capacities
provided the means for linking the preexisting conceptual operations with the
emerging lexical operations. In Edelman's picture, consciousness is liberation from the present. Animals tend
to live in the present, simply reacting to stimuli. Only conscious animals can
think about the past and about the future. As for the “place” where
consciousness happens (its neural correlate), Edelman noted that consciousness is
unified and a "whole", while nothing in the brain seems to be unified
and a "whole": in fact, the brain is made of a multitude of regions
that exhibit independent personalities. Consciousness must therefore be due to
a global process that encompasses more than one region. He believes that the
thalamocortical system originates such an activity: a massive, coherent
(synchronized) activity by all regions of the brain, that transcends the
individual activity of each region. Basically, consciousness is a process that
happens throughout the brain, not manufactured in a specific region. The location of
consciousness is changing all the time, as different groups of interacting
regions form and dissolve. At any moment in time, the “dynamic core” of primary
consciousness is located in the interaction between the thalamus and the
cortex. He does envision one particular region as being the permanent site of
consciousness. In a sense, consciousness is the “process” not the “place”. Back to the beginning of the chapter "Consciousness: the Factory of Illusions" | Back to the index of all chapters |