- Email: [email protected]
Directionally selective surround inhibition in the macaque MT area
S162 DIRECTIONALLY SELECTIVE SURROUND INHIBITION IN THE MACAQUE MT AREA.
KEIJI TANAKA ~, HIDE-AKI SAITO, YOSHIRO FUKADA, KAZUO HIKOSAKA*, MASAO YUKIE ~ and EIICHI IWAI, NHK Sei. and Teeh. Res. Labs., Setagaya, Tokyo 157 and Dept. of Behav. Physiol, Tokyo Metropolitan Inst. for Neurosei., Fuchu, Tokyo 188. Cells in the prestriate MT area respond to moving stimuli, with directional selectivity. Using monkeys (M. Fuscata) anesthetized with a gas of N20/O 2 (75:25), we examined their responses to two kinds of visual stimuli: movement of a slit; and movement of a two dimensional array of small dots (0.7 ° in diameter with 2 ° interval between centers). When the stimuli were limited within the excitatory field, most cells responded equally well to the two stimuli. However, half of them failed to respond to the dot pattern when the stimulated area extended over a wide field (70°x55°). This shows that their excitatory fields are surrounded by silent inhibitory fields. The remaining cells lacked such inhibitory surround fields and responded well to the wide field movement. The surround inhibition was further examined by stimulating the excitatory center field with a slit, and the inhibitory surround field with the dot pattern independently. I) The inhibitory effect is selective to the direction and speed of motion: response to the slit movement was suppressed when the dot pattern moved together with the slit in the same direction and speed; but the response was not changed when the surround movement deviated from the optimized slit movement by more than 60 ° in direction or 4 times in speed. 2) The inhibitory field extends to all radial directions, and over a wide area 4-20 times as large as the excitatory field. The MT cells which have the above characteristics are well qualified for analysis of a local movement of an object, d i s c r i m i n a t i n g it from an element of a large field movement such as that caused by a self-movement of the animal. D E T E C T I O N OF STRAIGHT AND ROTARY M O V E M E N T S OF STIMULI IN M A C A Q U E STS
M A S A O YUKIE*, K A Z U O HIKOSAKA*, EIICHI IWAI, HIDE-AKI SAITO, KEIJI TANAKA* and Y O S H I R O FUKADA, Dept. of Behav. Physiol., Tokyo M e t r o p o l i t a n Inst. for N e u r o sci., Fuchu, Tokyo 183, and N H K Sci. and Tech. Res. Labs., Setagaya, Tokyo 157. Using monkeys, we have studied visual response properties of n e u r o n s in the anterior bank of the superior temporal sulcus (STS) w h i c h lies a n t e r i o r l y adjacent to area M T and receives fiber p r o j e c t i o n s from it. During the experiment, the animal was a n a e s t h e t i z e d with a m i x t u r e of nitrous oxide and oxygen (70:30) and immobilized w i t h gallamine triethiodide. We identified.a restricted region w h e r e three kinds of d i r e c t i o n - s e l e c t i v e cells clustered: D-cells (157/299) responded to straight m o v e m e n t s of stimuli in the f r o n t o p a r a l l e l plane; S-cells (57/299) responded to either e x p a n s i o n or c o n t r a c t i o n of stimuli in the frontoparallel plane; R-cells (25/299) responded to the r o t a t i o n of patterns, some to either clockwise or c o u n t e r c l o c k w i s e rotations in the frontoparallel plane (Rcw- or Rccw-cells), and others to r o t a t i o n in depth (Rd-cells). All of these three kinds of cells had an extremely large receptive field, m o s t l y including the fovea, and w e r e driven by s t i m u l a t i o n of each eye to the same degree as by b i n o c u l a r stimulation. These r e c e p t i v e field p r o p e r t i e s can be m a d e up by integrative c o n v e r g e n c e of m o t i o n i n f o r m a t i o n provided by MT cells: D-cells receive inputs from MT cells w i t h the same p r e f e r e d direction; w h i l e S- and R-cells receive inputs from M T cells w h i c h have different p r e f e r e d directions. Further, it is suggested that this set of three kinds of d i r e c t i o n - s e l e c t i v e cells w o u l d provide the parietal cortex w i t h fundamental m o t i o n information, i.e., straight m o t i o n in the e q u i d i s t a n t plane (D-cells) and in depth (S-cells), and rotary m o t i o n in the e q u i d i s t a n t plane (Rcw- and Rccw-cells) and in depth (Rd-cells), which is n e c e s s a r y for the animal to perceive relative m o t i o n b e t w e e n the visual space and self.
KEIJI TANAKA ~, HIDE-AKI SAITO, YOSHIRO FUKADA, KAZUO HIKOSAKA*, MASAO YUKIE ~ and EIICHI IWAI, NHK Sei. and Teeh. Res. Labs., Setagaya, Tokyo 157 and Dept. of Behav. Physiol, Tokyo Metropolitan Inst. for Neurosei., Fuchu, Tokyo 188. Cells in the prestriate MT area respond to moving stimuli, with directional selectivity. Using monkeys (M. Fuscata) anesthetized with a gas of N20/O 2 (75:25), we examined their responses to two kinds of visual stimuli: movement of a slit; and movement of a two dimensional array of small dots (0.7 ° in diameter with 2 ° interval between centers). When the stimuli were limited within the excitatory field, most cells responded equally well to the two stimuli. However, half of them failed to respond to the dot pattern when the stimulated area extended over a wide field (70°x55°). This shows that their excitatory fields are surrounded by silent inhibitory fields. The remaining cells lacked such inhibitory surround fields and responded well to the wide field movement. The surround inhibition was further examined by stimulating the excitatory center field with a slit, and the inhibitory surround field with the dot pattern independently. I) The inhibitory effect is selective to the direction and speed of motion: response to the slit movement was suppressed when the dot pattern moved together with the slit in the same direction and speed; but the response was not changed when the surround movement deviated from the optimized slit movement by more than 60 ° in direction or 4 times in speed. 2) The inhibitory field extends to all radial directions, and over a wide area 4-20 times as large as the excitatory field. The MT cells which have the above characteristics are well qualified for analysis of a local movement of an object, d i s c r i m i n a t i n g it from an element of a large field movement such as that caused by a self-movement of the animal. D E T E C T I O N OF STRAIGHT AND ROTARY M O V E M E N T S OF STIMULI IN M A C A Q U E STS
M A S A O YUKIE*, K A Z U O HIKOSAKA*, EIICHI IWAI, HIDE-AKI SAITO, KEIJI TANAKA* and Y O S H I R O FUKADA, Dept. of Behav. Physiol., Tokyo M e t r o p o l i t a n Inst. for N e u r o sci., Fuchu, Tokyo 183, and N H K Sci. and Tech. Res. Labs., Setagaya, Tokyo 157. Using monkeys, we have studied visual response properties of n e u r o n s in the anterior bank of the superior temporal sulcus (STS) w h i c h lies a n t e r i o r l y adjacent to area M T and receives fiber p r o j e c t i o n s from it. During the experiment, the animal was a n a e s t h e t i z e d with a m i x t u r e of nitrous oxide and oxygen (70:30) and immobilized w i t h gallamine triethiodide. We identified.a restricted region w h e r e three kinds of d i r e c t i o n - s e l e c t i v e cells clustered: D-cells (157/299) responded to straight m o v e m e n t s of stimuli in the f r o n t o p a r a l l e l plane; S-cells (57/299) responded to either e x p a n s i o n or c o n t r a c t i o n of stimuli in the frontoparallel plane; R-cells (25/299) responded to the r o t a t i o n of patterns, some to either clockwise or c o u n t e r c l o c k w i s e rotations in the frontoparallel plane (Rcw- or Rccw-cells), and others to r o t a t i o n in depth (Rd-cells). All of these three kinds of cells had an extremely large receptive field, m o s t l y including the fovea, and w e r e driven by s t i m u l a t i o n of each eye to the same degree as by b i n o c u l a r stimulation. These r e c e p t i v e field p r o p e r t i e s can be m a d e up by integrative c o n v e r g e n c e of m o t i o n i n f o r m a t i o n provided by MT cells: D-cells receive inputs from MT cells w i t h the same p r e f e r e d direction; w h i l e S- and R-cells receive inputs from M T cells w h i c h have different p r e f e r e d directions. Further, it is suggested that this set of three kinds of d i r e c t i o n - s e l e c t i v e cells w o u l d provide the parietal cortex w i t h fundamental m o t i o n information, i.e., straight m o t i o n in the e q u i d i s t a n t plane (D-cells) and in depth (S-cells), and rotary m o t i o n in the e q u i d i s t a n t plane (Rcw- and Rccw-cells) and in depth (Rd-cells), which is n e c e s s a r y for the animal to perceive relative m o t i o n b e t w e e n the visual space and self.