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Cross-correlation analysis of intrinsic connections in area V2 of the monkey visual cortex: A comparative study with area V1
S203
1721
PERCEPTUAL FILLING-IN AT MONOCULAR SCOTOMA DO NOT REQUIRE REORGANIZATION OF THE RETINOTOPIC MAP OF THE MONKEY VI. MASAHARU KINOSHITA, IKUYA MURAKAMI,
TATSUYA KIMURA AND HIDEHIKO KOMATSU, Neuroscience Section, Electrotechnical Laboratory, Tsukuba-shi, Ibaraki 305, Japan
PURPOSE. In the blind spot, we perceive the same color and brightness as surrounding visual field. This perceptual “filling-in” has also been found to occur at the artificially-induced scotoma of the macaque. Several groups have reported that reorganization of retinotopic map in the striate cortex occurs after making binocular retinal lesion, and suggested that this reorganization may be responsible for the occurrence of filling-in (Gilbert & Wiesel, 1992, Kaas et al, 1990). The present study aims to determine whether or not the retinotopic map in the macaque primary visual cortex (Vl) is reorganized after making monocular retinal lesion, which leads to the filling-in at the resulting scotoma. METHOD. After trained to a fixation task and a saccade task, a monkey was anesthetized and a small retinal lesion was made in the left eye using a laser photocoagulator. The region of the artificial scotoma was identified and filling-in at the scotoma was confirmed with a discrimination task as reported previously (Murakami & Komatsu, 1993). Then, multiunit recordings were made in Vl around the representation of the scotoma and receptive fields (RFs) were mapped using a small light spot. RESULTS. With a monocular scotoma, we found no clear irregularity in the retinotopic organization of binocularly or monocularly (the non-lesioned eye only) mapped RFs. Monocularly (the lesioned eye only) mapped RI+ did not differ from binocularly mapped ones about their locations, except that neurons did not respond to spots within the scotoma. We found no enlargement of RF sizes at scotoma. CONCLUSION. These findings suggest that the neural mechanisms for perceptual “filling-in” at the scotoma do not necessarily require the reorganization of xetinotopic cortical maps.
1722
CROSS-CORRELATION
ANALYSIS OF INTRINSIC CONNECTIONS IN AREA V2 OF THE MONKEY
VISUAL CORTEX: A COMPARATIVE STUDY WITH AREA Vl . SATO’ . NARUMI KATSUYAMA’ & TADAHARU TSUMOTO’ , ’Dept.
HIROSHI TAMUR4’ y2, HIROMICHI
Neurophysiol.,
Osaka Univ.
Med. Sch.,
Suita,
Osaka, 565, 2Lab. for Neural Information Processing, RlKEN, Wako, Saitama, 351-01, JAPAN. To compare the intracortical functional connections in area V2 with those in area VI, we carried out cross-correlation analysis of spike trains recorded from cell pairs in the two areas. Recordings were made by a pair of electrodes from 4 macaque monkeys (M. fuscara), anesthetized with 70% N20 and 0.2-0.5% halothane. The distance between pairs of cells ranged from 200 to 2500 There were three different urn and their distributions were almost identical between two areas. points in features of cross-correlograms between Vl and V2. 1) Peaked correlograms, which indicated the presence of functional connections between pairs of cells, were observed in a larger proportion of cell pairs in V2 (47% of 130 pairs) than in Vl (30% of 77 pairs); 2) The width of peaks were broader in V2 (28 ms) than in Vl (4.9 ms); 3) The incidence of the peaked correlograms did not depend on the distance between cells or the difference in their optimal orientations in V2, whereas there was a clear than those in VI. dependency in VI. We suggest that intrinsic connections in V2 are more divergent
1723
FUNCTIONAL CONNECTIVITY BETWEEN AREA 17 AND LATERAL SUPRASYLVIAN AREA REVEALED BY CROSS-CORRELATION ANALYSIS IN THE CATS. NARUMI KATSUYAMA’, HIROMICHI SATO’, HIROSHI TAMURA2, MITSUHIRO FUKUDA’, AND TADAHARU TSUMOTOi,lDeut. Neurouhvsiol.. Biomed. Res. Ctr.. Osaka Univ. Med. Sch., Suita. Osaka. 565, 2Lab. Information
Processing.
RIKEN.
Wako.
Saitama.
351-01.
JAPAN
The posteromedial lateral suprasylvian area (PMLS) is one of extrastriate visual areas in cats, and thought to be involved in motion perception, stereopsis and eye movements. To assess the functional connectivity between area 17 and PMLS, we simultaneously recorded single unit activities from both areas in cats, and carried out cross-correlation analysis of spike trains. Animals were anesthetized with a mixture of 70 % N20, 30 % 02 and 0.3 - 0.5 % halothane and paralyzed with gallamine-triethiodide (10 mg/kg/hr, i.v.). Peaked cross-correlograms which indicate common inputs and/or excitatory drive were most often obtained from cell pairs whose receptive fields were overlapped. Also, significantly correlated activities were seen in cell pairs whose preferred direction of motion of visual stimuli differed by less than 60 degree from each other, whereas such correlated activities were not seen in pairs with difference in direction preference more than 90 degrees. These results suggest that the functional connections between area 17 and PMLS exist in cell populations with similar stimulus selectivities.
1721
PERCEPTUAL FILLING-IN AT MONOCULAR SCOTOMA DO NOT REQUIRE REORGANIZATION OF THE RETINOTOPIC MAP OF THE MONKEY VI. MASAHARU KINOSHITA, IKUYA MURAKAMI,
TATSUYA KIMURA AND HIDEHIKO KOMATSU, Neuroscience Section, Electrotechnical Laboratory, Tsukuba-shi, Ibaraki 305, Japan
PURPOSE. In the blind spot, we perceive the same color and brightness as surrounding visual field. This perceptual “filling-in” has also been found to occur at the artificially-induced scotoma of the macaque. Several groups have reported that reorganization of retinotopic map in the striate cortex occurs after making binocular retinal lesion, and suggested that this reorganization may be responsible for the occurrence of filling-in (Gilbert & Wiesel, 1992, Kaas et al, 1990). The present study aims to determine whether or not the retinotopic map in the macaque primary visual cortex (Vl) is reorganized after making monocular retinal lesion, which leads to the filling-in at the resulting scotoma. METHOD. After trained to a fixation task and a saccade task, a monkey was anesthetized and a small retinal lesion was made in the left eye using a laser photocoagulator. The region of the artificial scotoma was identified and filling-in at the scotoma was confirmed with a discrimination task as reported previously (Murakami & Komatsu, 1993). Then, multiunit recordings were made in Vl around the representation of the scotoma and receptive fields (RFs) were mapped using a small light spot. RESULTS. With a monocular scotoma, we found no clear irregularity in the retinotopic organization of binocularly or monocularly (the non-lesioned eye only) mapped RFs. Monocularly (the lesioned eye only) mapped RI+ did not differ from binocularly mapped ones about their locations, except that neurons did not respond to spots within the scotoma. We found no enlargement of RF sizes at scotoma. CONCLUSION. These findings suggest that the neural mechanisms for perceptual “filling-in” at the scotoma do not necessarily require the reorganization of xetinotopic cortical maps.
1722
CROSS-CORRELATION
ANALYSIS OF INTRINSIC CONNECTIONS IN AREA V2 OF THE MONKEY
VISUAL CORTEX: A COMPARATIVE STUDY WITH AREA Vl . SATO’ . NARUMI KATSUYAMA’ & TADAHARU TSUMOTO’ , ’Dept.
HIROSHI TAMUR4’ y2, HIROMICHI
Neurophysiol.,
Osaka Univ.
Med. Sch.,
Suita,
Osaka, 565, 2Lab. for Neural Information Processing, RlKEN, Wako, Saitama, 351-01, JAPAN. To compare the intracortical functional connections in area V2 with those in area VI, we carried out cross-correlation analysis of spike trains recorded from cell pairs in the two areas. Recordings were made by a pair of electrodes from 4 macaque monkeys (M. fuscara), anesthetized with 70% N20 and 0.2-0.5% halothane. The distance between pairs of cells ranged from 200 to 2500 There were three different urn and their distributions were almost identical between two areas. points in features of cross-correlograms between Vl and V2. 1) Peaked correlograms, which indicated the presence of functional connections between pairs of cells, were observed in a larger proportion of cell pairs in V2 (47% of 130 pairs) than in Vl (30% of 77 pairs); 2) The width of peaks were broader in V2 (28 ms) than in Vl (4.9 ms); 3) The incidence of the peaked correlograms did not depend on the distance between cells or the difference in their optimal orientations in V2, whereas there was a clear than those in VI. dependency in VI. We suggest that intrinsic connections in V2 are more divergent
1723
FUNCTIONAL CONNECTIVITY BETWEEN AREA 17 AND LATERAL SUPRASYLVIAN AREA REVEALED BY CROSS-CORRELATION ANALYSIS IN THE CATS. NARUMI KATSUYAMA’, HIROMICHI SATO’, HIROSHI TAMURA2, MITSUHIRO FUKUDA’, AND TADAHARU TSUMOTOi,lDeut. Neurouhvsiol.. Biomed. Res. Ctr.. Osaka Univ. Med. Sch., Suita. Osaka. 565, 2Lab. Information
Processing.
RIKEN.
Wako.
Saitama.
351-01.
JAPAN
The posteromedial lateral suprasylvian area (PMLS) is one of extrastriate visual areas in cats, and thought to be involved in motion perception, stereopsis and eye movements. To assess the functional connectivity between area 17 and PMLS, we simultaneously recorded single unit activities from both areas in cats, and carried out cross-correlation analysis of spike trains. Animals were anesthetized with a mixture of 70 % N20, 30 % 02 and 0.3 - 0.5 % halothane and paralyzed with gallamine-triethiodide (10 mg/kg/hr, i.v.). Peaked cross-correlograms which indicate common inputs and/or excitatory drive were most often obtained from cell pairs whose receptive fields were overlapped. Also, significantly correlated activities were seen in cell pairs whose preferred direction of motion of visual stimuli differed by less than 60 degree from each other, whereas such correlated activities were not seen in pairs with difference in direction preference more than 90 degrees. These results suggest that the functional connections between area 17 and PMLS exist in cell populations with similar stimulus selectivities.