Neuronal correlates of parametric working memory in the prefrontal cortex.

TitleNeuronal correlates of parametric working memory in the prefrontal cortex.
Publication TypeJournal Article
Year of Publication1999
AuthorsRomo, R, Brody, CD, Hernández, A, Lemus, L
JournalNature
Volume399
Issue6735
Pagination470-3
Date Published1999 Jun 3
ISSN0028-0836
KeywordsAnimals, Discrimination Learning, Humans, Macaca mulatta, Memory, Short-Term, Neurons, Prefrontal Cortex
Abstract

<p>Humans and monkeys have similar abilities to discriminate the difference in frequency between two mechanical vibrations applied sequentially to the fingertips. A key component of this sensory task is that the second stimulus is compared with the trace left by the first (base) stimulus, which must involve working memory. Where and how is this trace held in the brain? This question was investigated by recording from single neurons in the prefrontal cortex of monkeys while they performed the somatosensory discrimination task. Here we describe neurons in the inferior convexity of the prefrontal cortex whose discharge rates varied, during the delay period between the two stimuli, as a monotonic function of the base stimulus frequency. We describe this as 'monotonic stimulus encoding', and we suggest that the result may generalize: monotonic stimulus encoding may be the basic representation of one-dimensional sensory stimulus quantities in working memory. Thus we predict that other behavioural tasks that require ordinal comparisons between scalar analogue stimuli would give rise to monotonic responses similar to those reported here.</p>

DOI10.1038/20939
Alternate JournalNature
PubMed ID10365959