The effect of local cooling of the surface of the cerebral cortex by means of a metal chamber implanted in the skull was studied while recording evoked and spontaneous electrical activity from the center of a cooled area of 1 cm 2 . Direct cortical responses to local stimulation of the cortical surface decreased rapidly and progressively to disappear at surface temperatures of 20–22 °C. Onset and peak latencies were prolonged with a Q 10 of 1.4 and 1.7 respectively. Response duration was prolonged with decreasing amplitude, having a Q 10 of about 2.6. Surface cooling to 8–12 °C was necessary to abolish all postsynaptic components of somatic and auditory evoked potentials, recruiting responses, and spontaneous barbiturate spindles. Latencies of these responses were also increased with a Q 10 of 1.3–1.4 while the Q 10 for amplitude was consistently higher (2.0–2.6). Allowing for a gradient of increasing temperature from surface to depth it is concluded that all synaptic processes are blocked at temperatures of 20–22 °C. Synaptic mechanisms determining latency were consistently different from those determining amplitude as judged by consistent differences in the Q 10 of latency and amplitude for all postsynaptic responses studied in these experiments.
No takes yet. Share an insight, caveat, or question.
Jasper et al. (1970) studied this question.