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Neurosurgeon Forum

Stereotactic and Functional

Local Field Potential Modulations of Reward System Structures in Risk Taking

Friday, May 3, 2024
2:55 PM – 2:59 PM CT
Location:  S401ab
Disclosure(s):
Natasha C. Hughes, BS: No financial relationships to disclose
Sarah K. Bick, MD: Varian Medical: Consultant (Terminated, February 28, 2023)
Dario J. Englot, MD, PhD: No financial relationships to disclose
Helen Qian: No financial relationships to disclose
Introduction: Risk-taking behavior is seen in many psychiatric disorders, including substance use and bipolar disorders. Understanding neural activity underlying risky decisions may identify targets for deep brain stimulation surgery or other therapies. Although human neuroimaging studies have implicated reward signaling regions including the orbitofrontal cortex (OFC), anterior cingulate (AC), and insula in risk-taking, neuroimaging lacks the high temporal resolution of electrophysiology techniques. However, studying these regions with electrophysiology in humans requires invasive implants, limiting current understanding of neural activity underlying risky decisions.

Methods: 11 patients with pharmacoresistant epilepsy who underwent stereotactic electroencephalography (SEEG) implantation performed a gambling task. In each trial, patients were shown a playing card and wagered on their card being higher than a hidden card, either betting low ($5) or high ($20). We analyzed high-risk (≤50% winning) trial recordings, comparing trials when patients subsequently bet high to trials when they bet low. Recordings were aligned to time of patient card presentation. EEG data were filtered (bandpass, 1-200Hz) and re-referenced to a common average. Cluster-based permutation tests identified time-frequency clusters that differed between high and low bets.

Results: Cluster-based permutation revealed a 40-100Hz power increase before high bets in the OFC (p=0.001), AC (p=0.001), and amygdala (p=0.005). The average time of this increase in each area was 0.41s, 0.46s, and 0.35s after card presentation respectively; timing was not significantly different between regions (Kruskal-Wallis, p=0.053). Before high bets, insula 1-60Hz power decreased 0.3-0.6s following card presentation (p=0.001) and amygdala 40-80Hz power decreased 0.5-0.7s following card presentation (p=0.001). Before low bets, OFC 1-30Hz power increased 0.5-1s after card presentation (p=0.001).

Conclusion : These findings identify local field potential modulations predicting risky decisions. An increase in high-frequency activity in the OFC, AC, and amygdala, followed by decreases in the insula and amygdala was associated with subsequent risky decisions. OFC low-frequency activity after card presentation was associated with low-risk decisions. These findings support identification of therapeutic targets for disorders of risk taking.