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FGPSWA95
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Literature
38 records
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study in rat sensorimotor cortex.
recordings were obtained from 107 layer V pyramidal neurons, subsequently
injected with biocytin for morphological reconstruction. Of the 107 neurons,
59 (55.1%) were identified as adapting (45) or non-adapting (13) regular
spiking neurons (RS), and 48 (44.9%) as intrinsically bursting (IB) neurons
discharging with an initial cluster of action potentials, which tended to
recur rhythmically in a subset of 19 cells. The block of IAR by extracellular
Cs+ did not affect burst generation, but enhanced the tendency to reburst in
IB neurons. A similar effect was induced by other procedures affecting
K(+)-dependent post-burst hyperpolarization. In IB neurons Ca2+ spikes had a
longer decay time than in RS neurons, however selective blockers of both low
and high threshold Ca2+ conductances failed to impair bursting activity. On
the contrary, the perfusion of the slices with 0.5-1 microM TTX suppressed
bursting behaviour in a critical time interval preceding the complete block of
Na(+)-dependent action potentials. It is concluded that the persistent Na+
current INAP is the most important intrinsic factor for the typical firing
properties of IB neurons, while Ca2+ and K+ conductances appear to contribute
towards shaping bursts and controlling their recurrence rate. The morphology,
connectivity and physiological properties of adapting and non-adapting RS
neurons are particularly suited to the processing of respectively phasic and
tonic inputs, whereas the properties of IB neurons are consistent with their
suggested role in cortical rhythmogenesis and in the pathophysiological
synchronized activities underlying epileptogenesis.
