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ZC99
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Literature
38 records
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the rat barrel cortex
whisker-evoked synaptic and spiking responses of single neurons in the barrel
cortex. On the basis of their intrinsic firing patterns, neurons could be
classified as either regular-spiking (RS) cells, intrinsically burst-spiking
(IB) cells, or fast-spiking (FS) cells. Some recordings responded to current
injection with a complex spike pattern characteristic of apical dendrites. All
cell types had high rates of spontaneous postsynaptic potentials, both
excitatory (EPSPs) and inhibitory (IPSPs). Some spontaneous EPSPs reached
threshold, and these typically elicited only single action potentials in RS
cells, bursts of action potentials in FS cells and IB cells, and a small, fast
spike or a complex spike in dendrites. Deflection of single whiskers evoked a
fast initial EPSP, a prolonged IPSP, and delayed EPSPs in all cell types. The
intrinsic firing pattern of cells predicted their short-latency whisker-evoked
spiking patterns. All cell types responded best to one or, occasionally, two
primary whiskers, but typically 6-15 surrounding whiskers also generated
significant synaptic responses. The initial EPSP had a relatively fixed
amplitude and latency, and its amplitude in response to first-order
surrounding whiskers was approximately 55% of that induced by the primary
whisker. Second- and third-order surrounding whiskers evoked responses of
approximately 27 and 12%, respectively. The latency of the initial EPSP was
shortest for the primary whiskers, longer for surrounding whiskers, and varied
with the neurons' depth below the pia. EPSP latency was shortest in the
granular layer, longer in supragranular layers, and longest in infragranular
layers. The receptive field size, defined as the total number of fast
EPSP-inducing whiskers, was independent of each cell's intrinsic firing type,
its subpial depth, or the whisker stimulus parameters. On average, receptive
fields included >10 whiskers. Our results show that single neurons
integrate rapid synaptic responses from a large proportion of the mystacial
vibrissae, and suggest that the whisker-evoked responses of barrel neurons are
a function of both synaptic inputs and intrinsic membrane properties.
