A major research program in neuroscience is to determine
the relations between the material order of the world
around us and the sensory-perceptual order of our experience;
and, to discover the central neural mechanisms of these
transformations. Our perceptual experiences are generated
by the integration of the central neural activity set
in motion by sensory stimuli with the activation of the
neural images of past experience, and with those of the
current central brain state. This combination is a construction.
The general problem of determining the neural basis of
these constructions, and of the brain mechanisms in perception
can now be studied in a variety of experiments in which
perceptual experiences and the underlying neural activities
are observed directly. This is presently the most successful
experimental paradigm used in perceptual neuroscience.
I consider in this lecture two of the many sets of unsolved
problems in the cortical mechanisms in perception. Firstly,
the unknown functional operations in the operation of
small cortical modules; and, secondly, the unknown functional
operations in the large-scale distributed systems of the
cerebral cortex.
I considered a number of sources of knowledge that bear
directly upon these problems; I list them here as questions
with answers.
1. What have phylogenetic and comparative studies
contributed to knowledge of the dynamic function of the
cerebral cortex? Answer: nothing.
2. What have anatomical studies contributed to knowledge
of the intrinsic or systems operations within the neocortex?
Answer: they provide the framework for a future knowledge
of operations, but nothing more.
3. What have studies of cortical ‘functional
organization’ contributed to understanding its intrinsic
function. Answer: nothing.
4. What have studies of the ontogenesis of the cerebral
cortex contributed to understanding its function? Answer:
nothing.
5. What have studies of synaptic transmission contributed
to knowledge of the dynamic actions in cortical microcircuits
and distributed systems? Answer: a great deal, the fundamental
knowledge to build on.
6. What have imaging studies contributed to understanding
dynamic cortical function. Answer: nothing.
I then summarized the present state of knowledge of the
properties of cortical microcircuits, with the conclusion
that these operations are emergents, and cannot be predicted
from the properties of their cellular constituents. The
lecture closed with some speculations about the methods
that may be of value in studies of these problems.
