Single neurons in posterior parietal cortex of monkeys encode cognitive set

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Primate Neurophysiology

Background:

• The posterior parietal cortex (PPC) is primarily known for processing spatial information within the dorsal visual pathway.
• Emerging evidence suggests PPC neural activity may also reflect nonspatial, task-related information.
• Cognitive set, crucial for task preparation, has been mainly linked to frontal cortex functions.

Purpose of the Study:

• To investigate whether neurons in the primate PPC encode signals related to cognitive set.
• To determine if the PPC contributes to the preparation of specific tasks.

Main Methods:

• Monkeys were trained on a cognitive set shifting paradigm.
• In this paradigm, advance cues indicated which of two task rules to apply to upcoming stimuli.
• Neural activity in the PPC was recorded during task performance.

Main Results:

• A subset of neurons in the PPC exhibited selective responses to cues indicating different task rules.
• These task-rule selective neurons were concentrated in the lateral bank of the intraparietal sulcus and the angular gyrus.
• This demonstrates a neural correlate for cognitive set within the PPC.

Conclusions:

• The primate PPC encodes signals related to cognitive set, extending its known functions beyond spatial processing.
• These findings implicate the PPC in the neural mechanisms underlying task preparation and rule-based behavior.
• The PPC's role in cognitive control may be more extensive than previously understood.