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1707 Effects of gyral area teo lesions on discrimination limens for reduced patterns in macaques
s193
1706 YUSUKE
CONTRIBUTION
OF GABAERGfC
INHlBlTION
TO STlMUtUS
OBJECTFEATURES IN THEINFERIOR TEMPORALCORTEX. MURAYAMA. Dent. CoPnit% Ncurosci.. Osaka Univ. Med.
SELECTlVlTY
FOR
YIWANG.ICHIROFUJITA, Sch., Osaka 565. Japan.
Neuronsin areaTE of the monkey infenor temporalcortex respondpreferentiallyto particularobjectfeatures. Llttle is known about the mechanismthat gives nseIOthis stjm&s selectivity. although it haspreviously beensuggestedthat 11is createdIII earlierstagesof the cortical pathway (V4 and TEO) We examinedeffects of microiantophoreticapplicationof bicuculine methiodide(BMI), a GABA-A receptor antagonist. on visual responsesof TE neurons using multibarrel electiodesin a Japanese monkey anesthetizedwith N20.
Effects of BMI applicationon individual neuronswere shmulus-
specific Visual responses 10 someeffecrlve stimuli were augmented,but thoseto otherswere not affected. Wnh BMI applrcation,responses were evokedin somecellsby stimuliwhich did not evoke responsesin themwlthout BMI applicatron. The latter effect was observedfor a part~ular range of stimuli which often activated other neuronsalong the sameor surroundingrecordingtracks. A generalincreaseof neuronalexcitability doesnot explain theseeffects. We suggestthat a processof creatingstimulusselectivity is in progressin the TE andthat GABAergic inhibitioncontributesto this process.
1707 Metropol.
EFFECTS PATTERNS Inst.
OF GYRAL AREA IN MACAQUES. for Neurosci.,
TEO LESIONS ON DISCRIMINATION SHIGEYA YAGINUMA, Dept. 2-6 Musashidai, Fuchu-shi,
LIMENS FOR REDUCED Behav. Physiol, Tokyo Tokyo 163, Japan.
Area TEO has been thought to be crucial for pattern perception because of its strong lesion effects on pattern discrimination. Our previous lesion study has shown, however, that when TEO lesions are limited to the gyral area of inferotemporal cortex, sparing adjacent superior temporal sulcal area, the lesions produce only slight deficits in postoperative retention and acquisition of pattern discrimination. In this study we examined the effects of the gyral area TEO lesions on discrimination limen tests for reduced patterns and compared them with those of conventional TED lesions whose dorsal boarder was the floor of the superior temporal sulcus. The gyral TEO lesions disrupted the performance of the monkeys in the discrimination limen tests. However, the degree of the disruption was smaller than that following the conventional TEO lesions.
1708
ESTIMATION IN
OF SOURCE MAN ANALYZED WITH
Dept.
Physiol.,
LOCATION OF VISUAL MOTION-RELATED SSB/DT METHOD. YOSHIO NAKAJIMA,
Sch. of Med.,
Chiba Univ.,
Chiba
EVOKED
POTENTIALS
ICHIRO SHIMOYAMA. 260, Japan.
Experiments were performed on healthy volunteers. Visual stimuli such as statianary wheel image and rotating wheel image were displayed on a tachistoscope at random intervals and orders. EEGs were recorded with 21 surface electrodes on the scalp using balanced non-cephalic reference. Evoked potentials elicited by the rotating wheel images, stationary wheel images ON and OFF were respectively averaged after the experiments. It was found that the rotating wheel images characteristically elicit negative potentials around the bilateral posterior temporal lobes with a peak latency of about 30Oms. To estimate current source location, the negative potentials were further analyzed using the SSB/DT (scalp-skull-brain head model/dipole tracing) method (Homma et al: Electroencephalogr Clin Neurophysiol, 1994; Neurosci Res, 1995). The results were discussed in relation with the reports obtained in monkeys.
1706 YUSUKE
CONTRIBUTION
OF GABAERGfC
INHlBlTION
TO STlMUtUS
OBJECTFEATURES IN THEINFERIOR TEMPORALCORTEX. MURAYAMA. Dent. CoPnit% Ncurosci.. Osaka Univ. Med.
SELECTlVlTY
FOR
YIWANG.ICHIROFUJITA, Sch., Osaka 565. Japan.
Neuronsin areaTE of the monkey infenor temporalcortex respondpreferentiallyto particularobjectfeatures. Llttle is known about the mechanismthat gives nseIOthis stjm&s selectivity. although it haspreviously beensuggestedthat 11is createdIII earlierstagesof the cortical pathway (V4 and TEO) We examinedeffects of microiantophoreticapplicationof bicuculine methiodide(BMI), a GABA-A receptor antagonist. on visual responsesof TE neurons using multibarrel electiodesin a Japanese monkey anesthetizedwith N20.
Effects of BMI applicationon individual neuronswere shmulus-
specific Visual responses 10 someeffecrlve stimuli were augmented,but thoseto otherswere not affected. Wnh BMI applrcation,responses were evokedin somecellsby stimuliwhich did not evoke responsesin themwlthout BMI applicatron. The latter effect was observedfor a part~ular range of stimuli which often activated other neuronsalong the sameor surroundingrecordingtracks. A generalincreaseof neuronalexcitability doesnot explain theseeffects. We suggestthat a processof creatingstimulusselectivity is in progressin the TE andthat GABAergic inhibitioncontributesto this process.
1707 Metropol.
EFFECTS PATTERNS Inst.
OF GYRAL AREA IN MACAQUES. for Neurosci.,
TEO LESIONS ON DISCRIMINATION SHIGEYA YAGINUMA, Dept. 2-6 Musashidai, Fuchu-shi,
LIMENS FOR REDUCED Behav. Physiol, Tokyo Tokyo 163, Japan.
Area TEO has been thought to be crucial for pattern perception because of its strong lesion effects on pattern discrimination. Our previous lesion study has shown, however, that when TEO lesions are limited to the gyral area of inferotemporal cortex, sparing adjacent superior temporal sulcal area, the lesions produce only slight deficits in postoperative retention and acquisition of pattern discrimination. In this study we examined the effects of the gyral area TEO lesions on discrimination limen tests for reduced patterns and compared them with those of conventional TED lesions whose dorsal boarder was the floor of the superior temporal sulcus. The gyral TEO lesions disrupted the performance of the monkeys in the discrimination limen tests. However, the degree of the disruption was smaller than that following the conventional TEO lesions.
1708
ESTIMATION IN
OF SOURCE MAN ANALYZED WITH
Dept.
Physiol.,
LOCATION OF VISUAL MOTION-RELATED SSB/DT METHOD. YOSHIO NAKAJIMA,
Sch. of Med.,
Chiba Univ.,
Chiba
EVOKED
POTENTIALS
ICHIRO SHIMOYAMA. 260, Japan.
Experiments were performed on healthy volunteers. Visual stimuli such as statianary wheel image and rotating wheel image were displayed on a tachistoscope at random intervals and orders. EEGs were recorded with 21 surface electrodes on the scalp using balanced non-cephalic reference. Evoked potentials elicited by the rotating wheel images, stationary wheel images ON and OFF were respectively averaged after the experiments. It was found that the rotating wheel images characteristically elicit negative potentials around the bilateral posterior temporal lobes with a peak latency of about 30Oms. To estimate current source location, the negative potentials were further analyzed using the SSB/DT (scalp-skull-brain head model/dipole tracing) method (Homma et al: Electroencephalogr Clin Neurophysiol, 1994; Neurosci Res, 1995). The results were discussed in relation with the reports obtained in monkeys.