Lesion-induced transient suppression of inhibitory function in rat neocortex in vitro.

摘要: The structural and functional consequences of a local thermolesion were examined in rat neocortex with electrophysiological vitro techniques immunocytochemistry. Age-matched untreated sham-operated animals served as controls analysed the same way. lesions consisted core coagulated tissue 2-3 mm diameter reached ventrally into deep cortical layers. After two days reactive astrocytes after nine dense gliosis observed immediate vicinity. Modifications intrinsic membrane characteristics synaptic network properties investigated intra- extracellular recording survival times one to eight days. Neurons recorded surrounding neocortical slices revealed significantly more depolarized resting potential higher neuronal input resistance. In comparison cells control slices, maximal discharge rates injection depolarizing current pulses neurons close focal lesion not altered burst firing was never observed. However, between postlesion 1 5, surroundings showed transient increase excitability. This hyperactivity most clearly pronounced at distance from centre (i.e. about 1-1.5 away border) characterized by long-duration field responses multiphasic long-lasting excitatory postsynaptic potentials orthodromic stimulation afferent input. lesion-induced hyperexcitability associated significant reduction peak conductance Cl(-)-dependent fast inhibitory K(+)-dependent long-latency potential, suggesting that intracortical GABAergic system functionally impaired. decrease inhibition prolonged N-methyl-D-aspartate receptor-mediated activity, which could be reversibly blocked D-amino-phosphonovaleric acid. addition, vicinity responded an stimulus burst. disturbance balance may only have profound influences on mechanisms information processing, but also lead expression epileptiform activity long-term deficits.