Simultaneous encoding of multiple potential reach directions in dorsal premotor cortex

Area of Science:

• Neuroscience
• Primate motor control
• Cognitive neuroscience

Background:

• Decision-making involves selecting among competing actions.
• The neural mechanisms for parallel action planning are not fully understood.
• The dorsal premotor cortex (PMd) is implicated in motor planning and selection.

Purpose of the Study:

• To investigate whether the primate brain generates directional signals for multiple reaching actions simultaneously.
• To determine the role of the dorsal premotor cortex (PMd) in parallel motor planning before a choice is made.

Main Methods:

• Electrophysiological recordings from dorsal premotor cortex (PMd) cells in a monkey.
• A reaching task with two instructed-delay periods: target presentation and cue identification.
• Analysis of neural activity correlating with potential and chosen reaching movements.

Main Results:

• During the initial delay period, PMd neurons exhibited directional signals for two potential reaching targets.
• During the second delay period, one signal diminished while the other predicted the monkey's chosen action.
• Neural activity demonstrated the simultaneous planning of multiple reaching movements.

Conclusions:

• The primate brain can generate discrete directional signals for multiple reaching actions in parallel before a decision.
• Dorsal premotor cortex (PMd) plays a crucial role in this parallel planning process.
• These findings support a model where several movements are planned concurrently before one is selected for execution.