Mushiake, H. | Search bioRxiv

bioRxiv2024

Diversity of set-related neuronal activity in the dorsal premotor cortex of monkeys during a path-planning task

Actions involve multiple levels. The dorsal premotor area (PMd) of the primate cerebral cortex is involved in the preparation of actions based on perceptual information. In this study, we recorded neuronal activity from the PMd of monkeys while they performed a path-finding task. In the task, the animals were required to move a cursor step by step to a goal in a maze-like display, and the arm movement and the direction of the cursor operation were dissociated. We observed neurons involved in the preparation of a single arm movement and neurons involved in the preparation of a single cursor operation. Cursor operation-related neurons were also obtained from the lateral prefrontal cortex (lPFC), but the PMd neurons showed more preparatory properties during the execution period than the lPFC neurons. Furthermore, we found neurons involved in the preparation of a specific sequence of cursor movements. The PMd included not only all types of single-shot preparatory neurons but also preparatory neurons for a variety of complex sequences for arm movements and cursor manipulation. These results suggest that the PMd contains diverse neurons involved in different levels of action preparation. Such diversity is one of the critical neural bases for robust goal-directed behavior in complex environments. SignificanceThere are different levels in actions. The dorsal premotor cortex (PMd) is involved in the preparation of actions based on perceptual information. Here, we recorded neuronal activity from the PM d of monkeys while performing a path-finding task, i.e., moving a cursor step by step to a goal in a maze-like display. In addition to neurons involved in the preparation of a single arm movement and neurons involved in the preparation of a single cursor operation, cells involved in the preparation of a specific sequence of cursor movements were observed. These results suggest that the PMd contains diverse neurons involved in different levels of action preparation. Such diversity is one of the critical neural bases for robust goal-directed behavior in complex environments.

neuroscience↗

bioRxiv2021

Experience resetting in reinforcement learning facilitates exploration-exploitation transitions during a behavioral task for primates

The exploration-exploitation trade-off is a fundamental problem in re-inforcement learning. To study the neural mechanisms involved in this problem, a target search task in which exploration and exploitation phases appear alternately is useful. Monkeys well trained in this task clearly understand that they have entered the exploratory phase and quickly acquire new experiences by resetting their previous experiences. In this study, we used a simple model to show that experience resetting in the exploratory phase improves performance rather than decreasing the greediness of action selection, and we then present a neural network-type model enabling experience resetting.

animal behavior and cognition↗

bioRxiv2019

Forelimb movements evoked by optogenetic stimulation of the macaque motor cortex

Optogenetics has become an indispensable tool for investigating brain functions. Although non-human primates are particularly useful models for understanding the functions and dysfunctions of the human brain, application of optogenetics to non-human primates is still limited. In the present study, we generated an effective adeno-associated viral vector serotype DJ to express channelrhodopsin-2 (ChR2) under the control of a strong ubiquitous CAG promoter and injected into the somatotopically identified forelimb region of the primary motor cortex in macaque monkeys. ChR2 was strongly expressed around the injection sites, and optogenetic intracortical microstimulation (oICMS) through a homemade optrode induced prominent cortical activity: Even single-pulse, short duration oICMS evoked long-lasting repetitive firings of cortical neurons. In addition, oICMS elicited distinct forelimb movements and muscle activity, which were comparable to those elicited by conventional electrical ICMS. The present study removed obstacles to optogenetic manipulation of neuronal activity and behaviors in non-human primates.

neuroscience↗