Retinotopic and nonretinotopic field potentials in cat visual cortex

Abstract

Two types of field potentials were identified in cat visual cortex using contrast reversal of oriented bar gratings: a short-latency fast-local component with a retinotopic organization similar to that seen with single-unit discharges at the same cortical site, and a slow, nonretinotopic component with a longer peak latency. The slow-distributed component had an extensive receptive field mapped by measuring the amplitude of binary kernels and showed strong inhibitory interactions within the receptive field. The peak latency of the slow-local component increased with distance from the retinotopic center, suggesting a possible conduction delay. Both components showed some orientation bias depending on the laminar location, but the bias could be independent of the orientation preferred by single units in the immediate vicinity. The present findings indicate that locally generated field potentials reflect cortical mechanisms for nonlinear integration over wide areas of the visual field.

Spatial and Temporal Features of Synaptic to Discharge Receptive Field Transformation in Cat Area 17

“…At first sight, the weak latency-distance relationship we obtained may appear to be at variance from that reported in the studies by Kitano et al (1994) for local field potentials, by Suder et al (2002) for spiking responses, by Bringuier et al (1999) for synaptic responses, and by Jancke et al (2004) with voltage-sensitive dyes, which all showed a significant increase in latency with increased distance from the middle of the RFs. There are several possible reasons for this discrepancy.…”

“…We emphasize that this conclusion is valid for high-frequency stimulation only, given that previous studies (Bringuier et al 1999;Kitano et al 1994) showed that stimulus temporal frequency has a strong impact on spatiotemporal integration in cat area 17. The consequences of these dynamic adjustments require further investigations.…”

“…In the study by Bringuier et al (1999) the subthreshold RF showed slowly propagating, long-distance responses when the stimulus rate was about 1 Hz, but not when using a stimulus rate (20 -30 Hz) compared with the one we used (20 Hz). Similarly, Kitano et al (1994) disclosed two components in their field potentials: a fast one, whose spatial spread did not exceed 5-7°; and a slow one (propagation speed Ͻ1 m/s), whose spatial distribution could be extremely wide (Յ15°from the RF center). Importantly, this slow component was markedly reduced or completely suppressed when the stimulation rate was Ͼ8 Hz.…”

“…First, the latencies were not measured the same way in all studies (see Bair et al 2003 for a related topic). Second, the use of stimuli with different energy may result in the activation of different sets of connections; thus it is possible that the thin bars we used to map the RFs possessed less energy and thus were less capable of activating remote regions of the subthreshold RFs, than the flashing gratings used by Kitano et al (1994) or by Bringuier et al (1999) in some of their experiments.…”

Mirror Symmetric Topographic Maps Can Arise from Activity-Dependent Synaptic Changes

“…• of the visual field has been described (Angelucci et al, 2002;Bringuier et al, 1999;Grinvald et al, 1994;Kitano et al, 1994;Levitt and Lund, 2002). In adult macaque monkeys, this roughly corresponds to a distance in V1 of 20mm.…”