Associative learning allows an individual to acquire an association between a sensory cue and an outcome resulting from a specific response. Associative learning plays a vital role in the ability to learn new associations that allow human beings to optimally respond to the world around them. Research in humans and primates supports an important role for the caudate in associative learning. Our objective was to determine whether caudate stimulation could modulate associative learning in humans and to examine the neural circuitry involved in this process.
Two subjects who underwent depth electrode placement for monitoring of refractory epilepsy were included in the study. During recording from intracranial electrodes, subjects participated in an associative learning task requiring them to learn associates presented image with a button press. For half of the presented images, bilateral caudate stimulation was performed at 2 mA and 200 Hz for one second during the feedback epoch after correct responses. Authors calculated the learning curve for stimulated and non-stimulated images using a state space model and calculated average power at electrode contacts in different spectral bands during the response and feedback epochs of the task and examined for correlation with the learning curve.
Caudate stimulation during correct feedback significantly improved associative learning. Stimulated image associations were learned more rapidly than non-stimulated image associations. Learning was associated with increased low gamma (30-55 Hz) power in the nucleus accumbens and increased theta (3-8 Hz) power in the dorsolateral prefrontal cortex.
Caudate stimulation during reinforcement of correct association enhances learning and is associated with power changes in both dopaminergic circuitry involved in reward processing and areas involved in associative processes. This supports a role for the caudate in integrating reward information with associations. Furthermore, this suggests a new potential target for neuromodulation in human memory disorders.
Materials provided by American Association of Neurological Surgeons (AANS). Note: Content may be edited for style and length.
Cite This Page: