Eye position effects on visual, memory, and saccade-related activity in areas LIP and 7a of macaque.
We studied the effect of eye position on the light-sensitive, memory, and saccade-related activities of neurons of the lateral intraparietal area and area 7a in the posterior parietal cortex of rhesus monkeys. A majority of the cells showed significant effects of eye position, for each of the 3 types of response. The direction tuning of the light-sensitive, memory and saccade responses did not change with eye position but the magnitude of the response did. Since previous work showed a similar effect for the light-sensitive response of area 7a neurons (Andersen and Mountcastle, 1983; Andersen et al., 1985b), the present results indicate that this modulating effect of eye position may be a general one, as it is found in 3 types of responses in 2 cortical areas. Gain fields were mapped by measuring the effect of eye position on the magnitude of the response at 9 different eye positions for each neuron. The gain fields were usually planar or largely planar for all 3 types of response in both areas, indicating that the magnitude of the response usually varies linearly with both horizontal and vertical eye position. A similar observation was made previously for the gain fields of the light-sensitive response of area 7a neurons (Andersen et al., 1985b). Although gain fields sloped in all directions for the population of cells, the gain field slopes of the light-sensitive, memory and saccade responses for individual cells were usually similar. It is proposed that these eye position effects play an important role in making coordinate transformations for visually guided movement.
Andersen
R A
RA
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
Bracewell
R M
RM
Barash
S
S
Gnadt
J W
JW
Fogassi
L
L
D000818:Animals; D005133:Eye Movements / Q000502:physiology*; D008253:Macaca mulatta; D008568:Memory / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D009801:Oculomotor Muscles / Q000502:physiology*; D010296:Parietal Lobe / Q000166:cytology / Q000502:physiology*; D012438:Saccades / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*