Monkey prefrontal neuronal activity coding the forthcoming saccade in an oculomotor delayed matching-to-sample task

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Oculomotor Research

Background:

• The dorsolateral prefrontal cortex (PFC) is implicated in cognitive functions, including decision-making and memory.
• Understanding the neural mechanisms of memory-guided eye movements is crucial for cognitive neuroscience.

Purpose of the Study:

• To investigate the role of the dorsolateral prefrontal cortex (PFC) in the selection and retention of memory-guided saccadic eye movements.
• To dissociate motor and visual factors influencing saccade direction during delay periods.

Main Methods:

• Recorded neural activity of PFC neurons in macaque monkeys performing a delayed matching-to-sample oculomotor task.
• Analyzed neuronal responses during different task periods (fixation, cue presentation, delay, and saccade execution).
• Quantified neuronal activity using directional dependency indices (DDI) and visual dependency indices (VDI).

Main Results:

• A significant proportion of PFC neurons (29%) showed increased activity during the delay period preceding saccade execution.
• Many of these delay-period neurons exhibited direction selectivity, correlating with the forthcoming saccade direction.
• During the delay period, PFC neuron activity was predominantly associated with saccade direction rather than visual cue patterns.

Conclusions:

• PFC neurons play a critical role in storing the direction of memory-guided saccades during delay periods.
• The same PFC neurons involved in memory storage may also contribute to the decision-making process for selecting saccade direction.