Influence of a visual landmark shift on memory-guided reaching in the monkey

Poster Session D - Monday, April 15, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Jennifer lin¹, Veronica Nacher¹, Hongying Wang¹, Saihong Sun¹, Xiaogang Yang¹, J. Douglas Crawford¹; ¹York University

The brain uses various sources of visual information, including both egocentric (e.g., object location relative to the eye) and allocentric cues (e.g., object location relative to visual landmarks) to aim movements. The main purpose of this study is to determine the influence of allocentric cue shifts on reaching responses in non-human primates. To do this, reach and gaze data were collected from one female Macaca mulatta monkey (ML) trained to perform a memory-guided reaching task. A landmark was presented at 1 of 15 locations on a touch screen. A visual target then appeared transiently at a variable location within or outside this virtual square, followed by a visual mask. After the mask, the landmark either reappeared at the same location (stable landmark condition) or shifted by 8 degrees in one of 8 directions (landmark shift condition). The fixation light then extinguished, signaling a reach to the target. ‘No-landmark’ controls were the same, but without the landmark. Compared to gaze responses, reach had lower variance and decreased reaching error. The presence of a stable landmark increased the accuracy of both gaze and touch responses and the precision of gaze. It also decreased the reaction time for both gaze and touch. In the landmark shift condition, reaches shifted partially (mean = 29%) with the landmark. We found the gaze responses to shift (mean = 38%) with the landmark too. Overall, this data suggests that the monkey is influenced by visual landmarks when reaching to remembered targets in a similar way as humans.

Topic Area: PERCEPTION & ACTION: Motor control