Temporal Dynamics of Cortical Adaptation
Date
2015
Authors
Dalefield, Martin
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Abstract
Adaptation of cortical neurons in response to prior stimulus
history and the timecourse
of recovery from adaptation were investigated at the level of
action potentials using
the juxtacellular single-cell loose-patch recording paradigm in
the barrel cortex of juvenile
rats. An experimental protocol that paired adaptor and test
deflections of the principal whisker
for a given neuron was applied in two phases of the study.
Experiment 1 involved two adaptor
conditions, differentiated by the duration of the adaptor
stimulus, presented with a limited
range of four adaptor-test temporal separations. Experiment 2
involved a single adaptor
condition followed by an expanded range of adaptor-test temporal
separations. Experiment 1
demonstrated that the time-course for recovery from adaptation
was dependent on the duration
of the adaptor stimulus. Experiment 2 demonstrated that recovery
of action potential responses
in the cortical population follows a sigmoidal pattern, in
contrast to the exponential decay of
adaptation at the post-synaptic potential level. Data from both
experiments provided evidence
for adaptation increasing trial-to-trial variability of neuronal
responses to stimuli as well as
reducing discriminability between the presence or absence of a
test stimulus of similar
characteristics to the adaptor stimulus. Morphological recovery
was achieved for a sample of
neurons, and case studies of the relationship between neurons’
morphology and functional
behaviour provide insights for further investigations into
adaptation and functional diversity
within the cortex.
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Keywords
Barrel cortex, adaptation, whiskers, neural coding, rats, juxtacellular, somatosensory, somatosensation
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