Faculty Collaboration Database

Laminar variation in threshold for detection of electrical excitation of striate cortex by macaques. J Neurophysiol 2005 Nov;94(5):3443-50

Date

08/05/2005

Pubmed ID

16079194

DOI

10.1152/jn.00407.2005

Scopus ID

2-s2.0-27144441451 (requires institutional sign-in at Scopus site)   68 Citations

Abstract

Macaques were trained to signal their detection of electrical stimulation applied by a movable microelectrode to perifoveal striate cortex. Trains of < or =100 cathodal, 0.2-ms, constant current pulses were delivered at 50 or 100 Hz. The minimum current that could be reliably detected was measured at successive depths along radial electrode penetrations through the cortex. The lowest detection thresholds were routinely encountered when the stimulation was applied to layer 3, particularly just at the juncture between layers 3 and 4A. On the average, there was a twofold variation in threshold along the penetrations, with the highest intracortical thresholds being in layers 4C and 6. Variations as high as 20-fold were obtained in some individual penetrations, whereas relatively little change was observed in others. The minimum detectable current was 1 muA at a site in layer 3, i.e., 10-100 times lower than that for surface stimulation. Because macaques, as do human subjects, find electrical stimulation of striate cortex to be highly similar at all loci (a phosphene in the human case), it is puzzling as to how such uniformity of effect evolves from the exceedingly intricate circuitry available to the effective stimuli. It is hypothesized that the stimulus captures the most excitable elements, which then suppress other functional moieties, producing only the luminance of the phosphene. Lowest thresholds presumably are encountered when the electrode lies among these excitable elements that can, with higher currents, be stimulated directly from some distance or indirectly by the horizontal bands of myelinated axons, the stria of Baillarger.

Author List

DeYoe EA, Lewine JD, Doty RW

Author

Edgar A. DeYoe PhD Adjunct Professor in the Radiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Behavior, Animal
Deep Brain Stimulation
Differential Threshold
Electric Stimulation
Evoked Potentials
Long-Term Potentiation
Macaca nemestrina
Nerve Net
Psychomotor Performance
Psychophysics
Refractory Period, Electrophysiological
Refractory Period, Psychological
Visual Cortex