Biomedical subjects

G Vaknin

Publications and source records attributed to G Vaknin.

3 recordsLinked to original sources

PubMed1991

Methods for studying the conductance changes associated with synaptic activation of forebrain slices: the interpretation of field potentials using CSD profiles.

In this report the cortical slice preparation and an array electrode that instantaneously records laminar field potentials are used to evaluate issues related to the interpretation of cortical CSD profiles. The major issues are: (1) what cell types are responsible for producing the source/sink pairs seen in CSD profiles; (2) what neurotransmitters are responsible for producing the sinks/sources seen in the CSD profile and do the sinks/sources reflect activation of receptors that produce inward currents, outward currents, or both; (3) can active and passive currents be distinguished; (4) do action potentials contribute to the CSD profile; and (5) can synaptic population with different kinetics and onset latencies be distinguished? Methods for analyzing neuronal circuits and analyzing CSDs quantitatively are discussed.

Animals↗

PubMed1991

Ontogenesis of the depressant activity of carbachol on synaptic activity in rat visual cortex.

We studied the ontogeny of muscarinic depression in the developing rat visual cortex using carbachol (a nonhydrolyzable cholinergic agonist) application to neocortical slices obtained from four postnatal age groups: 9-10 days, 15 days, 30-40 days and 18 months. Carbachol suppressed the evoked synaptic response of layers II-III to stimulation of layer II-III afferents. Atropine eliminated the carbachol effect, suggesting that it is mediated by muscarinic receptors. The results indicate a significant increase in muscarinic efficacy in the developing rat visual cortex.

Animals↗

PubMed1988

A method for calculating current source density (CSD) analysis without resorting to recording sites outside the sampling volume.

This article is part of a study on cortical microcircuitry in which flash evoked potentials (FEPs) were recorded from the anesthetized rat visual cortex. The FEPs were subjected to current source density analysis (CSD). One of the limitations of the CSD method is the need for recording sites outside the sampling volume, in order to obtain a full description of the CSD distribution. This problem is acute in the neocortex where a tissue/fluid boundary exists. A simple solution is provided based on the fact that the field potentials decay minimally under the conditions of these experiments. In the neocortex the most superficial recording site and the deepest recording site are used to provide the extra recording sites necessary to obtain a full description of the CSD distribution. This approach when tested by summing the current sinks and sources across all layers of cortex produces excellent results, with significant reduction of the residual sinks and sources.

Action Potentials↗