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1608 Linearity in color selective responses of macaque LGN neurons
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1606
VISUAL PATHWAY IN THE MONKEY CEREBRAL CORTEX MAPPED BY POSITRON EMISSION TOMOGRAPHY II: MOTION AND COLOR PERCEPTION Dept. Neurosci. Osaka Bioscience Institute ‘, Subfemtomole Biorecognition Project, Japan Science and Technology Corporation2, Dept. Cognitive Neurosci. Med.Sch. Osaka Univ.3, PET Ctr. Hamamatsu Photonics K.K.4 NARUMI KATSUYAMA’ , HIROTAKA ONOE ‘y2, KAZUYUKI IMAMURA’32, MASASHI KOMORIl, MAKOTO KAT03, HIDE0 TSUKADA2t4, YASUYOSHI WATANABE’t2 To understand the neuronal basis of higher brain functions, it is important to combine the functional mapping of brain and other conventional neuroscientific techniques. Recently, we have established the experimental system for functional brain mapping of behaving monkey by use of positron emission tomography (PET). In this study, as a first step of application of this system, we tried to visualize cortical areas involved in motion and color perception in monkey visual cortex. With visual stimulation of drifting grating, significant activities were observed in visual areas in the dorsal stream, such as MT and V6. In contrast, when colored Mondrian patterns were presented as visual stimulus, a significant activity wasobserved in the central representing part of V4. In addition, a cluster of signal was observed in the TEO. These results are consistent with the previous physiological data which indicate that MT, V4 and TEO play important roles in motion and color perception.
1607
Comparison of neuron’s responses in area TE to shape-color conjunctive stimuli between focused and divided attention tasks. Dept. of Behavioral Physiol., Tokyo Metropolitan Inst. for Neurosci. Takayuki Sato Macaque monkeys were trained to perform a conjunctive discrimination task for colored patterns and an associative discrimination tasks between gray pattern and color-spots. In the conjunctive discrimination task, one set of stimuli were consisted of four different colored patterns (2 colorsx2 patterns), and one of them were presented in each trial. In the later task, two stimuli were presented simultaneously at different locations, and the shapes and colors were corresponded to these in the former task. During the conjunctive discrimination task, approximately 30% of responsive neurons recorded in area TE showed an enhanced response to a particular colored pattern, e.g. red circle. The stimulus was mostly one of Go-stimuli to which the monkeys were required to release a lever quickly. However, in the associative discrimination task, the response of most of these neurons was not enhanced to the same combination of shape and color.
1608
LINEARITY
IN COLOR SELECTIVE
RESPONSES OF MACAQUE
LGN NEURONS
Lab. Neural Control, Natl. Inst. for Physiol. Sci. Hidehiko Komatsu, Akitoshi Hanazawa, Hideki Kondo In order to know if a transformation of color information occurs between the lateral geniculate nucleus (LGN) and Vl, we studied the color selectivities of neurons in the parvocellular layer of LGN (pLGN) and compared them with those observed in Vl. In one monkey, we studied responses of pLGN neurons to a set of equiluminant color stimuli whose colors were systematically distributed in the CIExy chromaticity diagram. In 39 color selective pLGN neurons, we examined if the responses fit to a model assuming a linear summation of cone signals. We found that responses of most of these neurons (34) fit well to the model (p
1606
VISUAL PATHWAY IN THE MONKEY CEREBRAL CORTEX MAPPED BY POSITRON EMISSION TOMOGRAPHY II: MOTION AND COLOR PERCEPTION Dept. Neurosci. Osaka Bioscience Institute ‘, Subfemtomole Biorecognition Project, Japan Science and Technology Corporation2, Dept. Cognitive Neurosci. Med.Sch. Osaka Univ.3, PET Ctr. Hamamatsu Photonics K.K.4 NARUMI KATSUYAMA’ , HIROTAKA ONOE ‘y2, KAZUYUKI IMAMURA’32, MASASHI KOMORIl, MAKOTO KAT03, HIDE0 TSUKADA2t4, YASUYOSHI WATANABE’t2 To understand the neuronal basis of higher brain functions, it is important to combine the functional mapping of brain and other conventional neuroscientific techniques. Recently, we have established the experimental system for functional brain mapping of behaving monkey by use of positron emission tomography (PET). In this study, as a first step of application of this system, we tried to visualize cortical areas involved in motion and color perception in monkey visual cortex. With visual stimulation of drifting grating, significant activities were observed in visual areas in the dorsal stream, such as MT and V6. In contrast, when colored Mondrian patterns were presented as visual stimulus, a significant activity wasobserved in the central representing part of V4. In addition, a cluster of signal was observed in the TEO. These results are consistent with the previous physiological data which indicate that MT, V4 and TEO play important roles in motion and color perception.
1607
Comparison of neuron’s responses in area TE to shape-color conjunctive stimuli between focused and divided attention tasks. Dept. of Behavioral Physiol., Tokyo Metropolitan Inst. for Neurosci. Takayuki Sato Macaque monkeys were trained to perform a conjunctive discrimination task for colored patterns and an associative discrimination tasks between gray pattern and color-spots. In the conjunctive discrimination task, one set of stimuli were consisted of four different colored patterns (2 colorsx2 patterns), and one of them were presented in each trial. In the later task, two stimuli were presented simultaneously at different locations, and the shapes and colors were corresponded to these in the former task. During the conjunctive discrimination task, approximately 30% of responsive neurons recorded in area TE showed an enhanced response to a particular colored pattern, e.g. red circle. The stimulus was mostly one of Go-stimuli to which the monkeys were required to release a lever quickly. However, in the associative discrimination task, the response of most of these neurons was not enhanced to the same combination of shape and color.
1608
LINEARITY
IN COLOR SELECTIVE
RESPONSES OF MACAQUE
LGN NEURONS
Lab. Neural Control, Natl. Inst. for Physiol. Sci. Hidehiko Komatsu, Akitoshi Hanazawa, Hideki Kondo In order to know if a transformation of color information occurs between the lateral geniculate nucleus (LGN) and Vl, we studied the color selectivities of neurons in the parvocellular layer of LGN (pLGN) and compared them with those observed in Vl. In one monkey, we studied responses of pLGN neurons to a set of equiluminant color stimuli whose colors were systematically distributed in the CIExy chromaticity diagram. In 39 color selective pLGN neurons, we examined if the responses fit to a model assuming a linear summation of cone signals. We found that responses of most of these neurons (34) fit well to the model (p