Single cell activity in the auditory cortex of the unanesthetized, behaving monkey: correlation with stimulus...

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Primate Research

Background:

• Auditory reaction time (RT) tasks are used to study auditory processing.
• Reinforcement conditions can influence behavioral responses and neural activity.

Purpose of the Study:

• To investigate how reinforcement conditions affect neural activity in the auditory cortex.
• To examine the relationship between behavioral state and neuronal responses in rhesus monkeys.

Main Methods:

• Electrophysiological recording of 60 auditory cortical cells in two rhesus monkeys.
• Behavioral training on a cued auditory reaction time task with varying reinforcement schedules (frequency irrelevant vs. frequency discrimination).
• Simultaneous measurement of neural activity and RT performance during different reinforcement conditions.

Main Results:

• Auditory reaction times were longer and more variable in the unrewarded (frequency discrimination) condition.
• 25% of auditory cortical neurons exhibited altered evoked activity correlated with reinforcement condition.
• Excitatory responses were generally increased in the unrewarded condition, with some cells showing changes in latency and discharge patterns.

Conclusions:

• Neural activity in the auditory cortex is dependent on the behavioral state of the preparation.
• Observed neural alterations are likely mediated by central mechanisms, not peripheral ones.
• Behavioral state is a relevant concept for understanding neurophysiological processes in auditory processing.