Human anterior cingulate cortex responses to the expected and the unexpected support the predicted response-outcome model of ACC function

Authors

• AR Weiss
• MJ Gillies
• TZ Aziz
• JJ FitzGerald
• JW Walters
• AL Green

Abstract

Conflict monitoring and error processing are essential executive functions for adaptation to conflicting information. Neuroimaging studies consistently report activity in the medial prefrontal cortex in cognitively demanding conditions, with the anterior cingulate cortex (ACC) believed to be principally active during action-monitoring processes. It is unclear whether ACC activity increases directly with the receipt of error feedback, or simply acts in the detection of response conflict. Ultimately, ACC basic function remains in dispute. This study aimed to investigate ACC function and the role it plays in human cognition. We analyzed local field potentials from electrophysiological recordings from bilateral ACC in chronic pain patients undergoing implantation of deep brain stimulation electrodes. Patients performed a modified Wisconsin card-sorting task, a test sensitive to shifting and flexibility of attention. Utilizing a pre-existing model of response conflict and error likelihood, we confirm that the ACC appears to be maximally inhibited when a predicted outcome occurs, and conversely maximally active when an outcome fails to occur. The associated unexpected non-occurrence signal drives reinforcement learning of new action-outcome associations and reveals a connection between conflict processing and theta frequency band activity. Our data offer a valuable electrophysiological comparison of ACC activity in response to sensory feedback during a cognitive task requiring conflict monitoring, error processing. This study is believed to be the first demonstration of sensory-evoked potentials in the ACC, and may offer fresh insight into the role of ACC in decision making and learning processes and on the nature of ACC physiology and pathophysiology.

Scientific Focus Area: Neuroscience

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