Monkey brain activity modulated by reward preferences: a positron emission tomography study

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Decision Neuroscience

Background:

• Motivation significantly impacts goal-directed actions, influenced by reward preferences and magnitudes.
• Previous research indicates reward preferences modulate neural activity in the striatum, lateral prefrontal cortex, and orbitofrontal cortex.
• However, the specific brain regions and mechanisms underlying motivational changes affecting rewarding actions remain incompletely understood.

Purpose of the Study:

• To investigate how brain activity in the lateral prefrontal cortex and other regions changes in response to varying reward preferences during a visuo-motor task in monkeys.
• To identify the neural correlates of subjective reward significance and its modulation of brain activity.

Main Methods:

• Assessed individual reward preferences through a choice test in two Japanese monkeys.
• Measured regional cerebral blood flow using positron emission tomography with H2(15)O during a visuo-motor task.
• Kept cognitive task demands constant while varying the motivational significance using different rewards (raisin, banana-flavored pellet, plain pellet, banana).

Main Results:

• Observed modulation of activity in the lateral prefrontal cortex, orbitofrontal cortex, parietal cortex, ventral and dorsal striatum, and cerebellum.
• These neural activities varied in accordance with the established reward preferences.
• Demonstrated a link between subjective reward value and neural modulation in specific brain areas.

Conclusions:

• The study identified key brain regions, including the lateral prefrontal cortex and striatum, whose activity is modulated by subjective reward preferences.
• These findings contribute to understanding the neural basis of motivation and how the brain integrates reward value into action selection.
• The results highlight the role of these regions in processing motivational significance derived from subjective reward values.