The Journal of Neuroscience, 2002, 22:RC198:1-6
RAPID COMMUNICATION
"Keeping on Track": Firing of Hippocampal Neurons during
Delayed-Nonmatch-to-Sample Performance
Robert E.
Hampson,
John D.
Simeral, and
Sam A.
Deadwyler
Department of Physiology and Pharmacology and the Neuroscience
Program, Wake Forest University School of Medicine, Winston-Salem,
North Carolina 27157
Hippocampal neurons that encode critical events during a
delayed-nonmatch-to-sample (DNMS) task were proposed to have functional topography as demonstrated by Hampson et al. (1999b). Functional cell types (FCTs) that encode similar task features were located within
alternating transverse segments along the hippocampal longitudinal axis. On this basis, Redish et al. (2001) suggested that firing of
populations of CA1 neurons recorded from the same hippocampal locations
in animals running on linear or curvilinear tracks should be spatially
and temporally correlated; however, they failed to find such
correlations. The current study addresses the issues raised by Redish
et al. (2001). Initially we found that modeling of simulated place
fields revealed absences in temporal correlations in the study by
Redish et al. (2001) that should have been present given the reported
spatial correlations. In addition, the correlation methods used by
those investigators failed to detect robust but transient event-related
cross-correlations between FCTs in the DNMS task. Furthermore,
demonstration of such transient, short-latency correlated firing
between similar CA3 and CA1 FCTs corroborated the anatomic scheme
proposed by Hampson et al. (1999b) and reaffirmed the potential
existence of a functional topography within hippocampus.
Key words:
ensemble; learning; memory; behavior; place field; cross-correlation
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