The effect of local cooling upon spontaneous and evoked electrical activity of cerebral cortex

Abstract

1970. The effect of local cooling upon spontaneous and evoked electrical activity of cerebral cortex. Can. J. Physiol. Pharrnacol. 48, 640-652.The effect of local cooling sf 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 cm2. Direct cortical responses to local stirnulatioir of the cortical surface decreased rapidly and progressively to dissppear at starface ternpcratures of 20-22 "C. Onset and peak latencies were prolonged with a Qlo of 1.4 and 1.7 respectively.Response duration was prolonged with decreasing an-nplitude, having a Q,, of about 2.6. Surface cooling to 8-12 "C was necessary to abolish all postsynaptic components of sorn;ltic and auditory evoked potentials, recruiting responses, and spontaneous barbiturate spindles. Latencies of these responses were also increased with a el,, of 1 .?-1.4 while the Qlo for arnplitude was consistently higher (2.8-2.4). Allowing for a gradient of increasing temperature from stirface to depth it is concluded that all synaptic processes are blockcd at tennperatrares of 20-22 "C. Synaptic mechanisms determining latency were csnsistenaly different from those afetern-mining amplitude as judged by consistent diflerences in the Qlo sf latency and amplitude for all postsynaptic responses studied in these experiments.

The cryoloop: an adaptable reversible cooling deactivation method for behavioral or electrophysiological assessment of neural function

“…8), there being a very steep gradient between 24 and 20°C along which the number of neuronal action potentials progressively decreases even for vigorously active neurons. These values conform with previous measurements of Jasper et al (1970) and Benita and Conde (1972).…”

Learning and recall of form discriminations during reversible cooling deactivation of ventral-posterior suprasylvian cortex in the cat.

“…), and temperatures in cortex were measured with microthermocouples (Omega Engineering, Stamford, CT). From these measurements we estimated the extent of deactivated cortex based on the observation that evoked activity is silenced by cooling of brain tissue to .20'C (9,11,12). The brain was then fixed, and horizontal sections were cut and stained for Nissl substance or myelin.…”

Functional specialization in non-primary auditory cortex of the cat: Areal and laminar contributions to sound localization

“…(4) Compared to traditional ablation studies, fewer animals are needed because within-animal-comparisons and double dissociations are possible, permitting large volumes of high quality data to be acquired from each animal . (5) Finally, as the major effect of cooling is to block synaptic transmission, activity in fibers of passage is not compromised (Jasper et al, 1970;Bénita and Condé, 1972). Overall, the technique induces localized hypothermia in a restricted region of the brain.…”