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ELECTRIC POTENTIALS ON OPTIC CORTEX EVOKED BY PHOTIC STIMULATION ON RETINA IN RABBIT'S
Author(s) -
Nakagawa Kiichiro
Publication year - 1957
Publication title -
psychiatry and clinical neurosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.609
H-Index - 74
eISSN - 1440-1819
pISSN - 1323-1316
DOI - 10.1111/j.1440-1819.1957.tb01204.x
Subject(s) - retina , stimulation , retinal , visual cortex , neuroscience , stimulus (psychology) , cortex (anatomy) , cerebral cortex , photic stimulation , anatomy , biology , psychology , medicine , ophthalmology , visual perception , psychotherapist , perception
Summary As the effect of strobo‐flashes of about 25 lux on dial‐anesthetized rabbit's retina in the state of dark adaptation, the following result was obtained: 1. The cortical‐evoked potentials caused by retinal photic stimulation have two parts, namely, the initial rasponses and the follow‐up ones. The initial responses occur immediately after application of the stimulus, to be differentiated into 3 types, i.e. the 1st type composed of positive waves, the 2nd type composed of negative waves, and the 3rd type composed of both negative and positive waves. The author regards the 1st and 3rd types as the patterns proper to the visual cortex. The follow‐up responses are positive discharges that follow the initial responses, in many cases appearing 3–6 times in succession. 2. The evoked potentials appear both distinctly and widely in the cortex contralateral to the stimulated retina while those of the homolateral cortex remain indistinct as well as limited in extent. Tracing of the extent of the response‐producing areas on M. Rose's map, it tells that the areas cover whole area of striata and a part of regio retrosplenialis granularis, regio parietalis, and area occipitalis. The 1st type tends to appear concentrated in area striata, the 2nd type in regio parietalis and regio retrosplenialis granularis, and the 3rd type circumambient the periphery of the area of the 1st type. The cortical responses of homolateral cerebral hemisphere being located in a much narrower area, the 1st and the 3rd types, representing properly positive waves, can be found only in a small range of the antero‐lateral part of area striata. 3. The latency of the evoked potential of contralateral cortex is 17 msec.‐30 msec., which is common to all the types, the majority of the 1st type responses is laden with latency of 21 msec., those of the 2nd and the 3rd types with that of 22 msec., throughout, there being no significant variance. The peaktime of the initial responses reads 24–45 msec., 30 msec. for the majority of the 1st type responses, again 31 msec. for that of the 2nd type. Both latency and initial peaktime of the homolateral cortical responses are a trifle later than those of contralateral cortical responses by about 6 msec. 4. The evoked potentials of the 1st and the 3rd type of contralateral responses come the highest in the antero‐medial portion of area striata not infrequently amounting to 400 μV and over, the next highest waves are obtained in the antero‐lateral portion of the same area, only to go declining toward caudally. The 2nd type responses are generally of lower amplitude than the other types, usually reading 100 μV or so, only seldom exceeding 200 μV. The homolaterally evoked cortical potentials are again low, all reading below 200 μV. 5. Comparing the cortical‐evoked potentials due to single stimulation on the optic nerve with those due to retinal photic stimulation, theri is hardly any variance in the wave patterns of the initial responses in both, excepting that latency is shorter and the follow‐up responses are entirely lacking in the former.