Connectionists: Laminar cortical dynamics of working memory, sequence learning, and performance

[Stephen Grossberg]

The following article is now available at 
<http://www.cns.bu.edu/Profiles/Grossberg>http://www.cns.bu.edu/Profiles/Grossberg 
:

Grossberg, S. and Pearson, L.
Laminar cortical dynamics of cognitive and motor working memory, 
sequence learning, and performance: Toward a unified theory of how 
the cerebral cortex works
Psychological Review, in press

ABSTRACT
How does the brain carry out working memory storage, categorization, 
and voluntary performance of event sequences? The LIST PARSE neural 
model proposes an answer to this question that unifies the 
explanation of cognitive, neurophysiological, and anatomical data 
from humans and monkeys. It quantitatively simulates human cognitive 
data about immediate serial recall and free recall, and monkey 
neurophysiological data from the prefrontal cortex obtained during 
sequential sensory-motor imitation and planned performance. The model 
clarifies why both spatial and non-spatial working memories share the 
same type of circuit design. It proposes how the laminar circuits of 
lateral prefrontal cortex carry out working memory storage of event 
sequences within layers 6 and 4, how these event sequences are 
unitized through learning into list chunks within layer 2/3, and how 
these stored sequences can be recalled at variable rates that are 
under volitional control by the basal ganglia. These laminar 
prefrontal circuits are variations of laminar circuits in the visual 
cortex that have been used to explain data about how the brain sees. 
These examples from visual and prefrontal cortex illustrate how 
laminar neocortex can represent both spatial and temporal 
information, and open the way towards understanding how other 
behaviors may be represented and controlled by variations on a shared 
laminar neocortical design.

Keywords: working memory, competitive queuing, immediate serial 
recall, immediate free recall,  delayed free recall, 
continuous-distracter free recall, sensory-motor imitation, chunking, 
sequence learning, prefrontal cortex, parietal cortex, position 
coding, rank order cells, cerebral cortex, laminar computing