title: GABA-induced inactivation of Cebus apella V2 neurons: effects on orientation tuning and direction selectivity.
abstract: We investigated the GABA-induced inactivation of V2 neurons and terminals on the receptive field properties of this area in an anesthetized and paralyzed Cebus apella monkey. Extracellular single-unit activity was recorded using tungsten microelectrodes in a monkey before and after pressure-injection of a 0.25 or 0.5 M GABA solution. The visual stimulus consisted of a bar moving in 8 possible directions. In total, 24 V2 neurons were studied before and after blocker injections in 4 experimental sessions following GABA injection into area V2. A group of 10 neurons were studied over a short period. An additional 6 neurons were investigated over a long period after the GABA injection. A third group of 8 neurons were studied over a very long period. Overall, these 24 neurons displayed an early (1-20 min) significant general decrease in excitability with concomitant changes in orientation or direction selectivity. GABA inactivation in area V2 produced robust inhibition in 80% and a significant change in directional selectivity in 60% of the neurons examined. These GABA projections are capable of modulating not only levels of spontaneous and driven activity of V2 neurons but also receptive field properties such as direction selectivity.
authors.affiliation: Universidade Federal do Pará, Instituto de Ciências Biológicas, BelémPA, Brasil.
authors.forename: A K
authors.initials: AK
authors.lastname: Jansen-Amorim
authors.forename: M
authors.initials: M
authors.lastname: Fiorani
authors.forename: R
authors.initials: R
authors.lastname: Gattass
mesh_terms: D000818:Animals; D002428:Cebus; D004562:Electrocardiography; D018682:GABA Agents / Q000494:pharmacology*; D008012:Lidocaine / Q000378:metabolism; D008297:Male; D008839:Microelectrodes; D009433:Neural Inhibition / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D009949:Orientation / Q000187:drug effects*; D010775:Photic Stimulation; D013997:Time Factors; D014793:Visual Cortex / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology* / Q000502:physiology
chemical_list: D018682:GABA Agents; D005680:gamma-Aminobutyric Acid; D008012:Lidocaine
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