A code for behavioral inhibition on the basis of color, but not motion, in ventrolateral prefrontal cortex of macaque monkey.
To examine the neural mechanism for behavioral inhibition, we recorded single-cell activity in macaque ventrolateral prefrontal cortex, which is known to receive visual information directly from the inferotemporal cortex. In response to a moving random pattern of colored dots, monkeys had to make a go or no-go response. In the color condition, green indicated go, whereas red indicated no-go, regardless of the motion direction; in the motion condition, upward indicated go, whereas downward indicated no-go, regardless of the color. Approximately one-half of the visual cells were go/no-go differential. A majority of these cells (64/73) showed differential activity only in the color condition; they responded nondifferentially in the motion condition, although the same set of stimuli was used. We classified these cells as "go type" (n = 41) and "no-go type" (n = 23) depending on the color for which they showed a stronger response. Interestingly, in both types of cells, the differential effects were observed only for the no-go-indicating color. Compared with the nondifferential responses in the motion condition, go-type cells in the color condition showed weaker responses to the no-go-indicating color, whereas their responses to the go-indicating color were similar; in contrast, no-go type cells showed stronger responses to the no-go-indicating color, whereas their responses to the go-indicating color were similar. Both types of cells did not show any activity change during the actual execution of the go or no-go response. These results suggest that neurons in ventrolateral prefrontal cortex contribute to stimulus-response association in complex task situations by inhibiting behavioral responses on the basis of visual information from the ventral stream.
Sakagami
M
M
Department of Physiology, Juntendo University, School of Medicine, Bunkyo, Tokyo, Japan 113-8421. sakagami@lab.tamagawa.ac.jp
Tsutsui Ki
Lauwereyns
J
J
Koizumi
M
M
Kobayashi
S
S
Hikosaka
O
O
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology; D003118:Color Perception / Q000502:physiology*; D003463:Cues; D004193:Discrimination Learning / Q000502:physiology; D004567:Electrodes, Implanted; D005074:Evoked Potentials, Visual / Q000502:physiology; D005403:Fixation, Ocular / Q000502:physiology; D007266:Inhibition, Psychological; D008251:Macaca; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000502:physiology; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000166:cytology / Q000502:physiology*