Beta-Band Power Modulation in the Human Amygdala During a Delayed Reach Task

Abstract

IntroductionThe amygdala is mostly known for its roles in emotional processing and social behavior. In recent years, it has been implicated in voluntary motor control due to its structural and functional connectivity with the motor cortex. By investigating whether the amygdala modulates during movement planning, we can further examine its contributions to motor processing.ObjectiveWe utilized a delayed reach task to measure beta-band (13-30 Hz) modulation in the amygdala during movement planning. We hypothesized that we would see decreases in beta-band power during the Delay and Response phases of this task.MethodsEleven subjects diagnosed with drug-resistant epilepsy (DRE), who were implanted with stereoelectroencephalographic (SEEG) electrodes, were recruited to this study. The beta-band power was recorded through a delayed reach task. We calculated the beta-band Power Spectral Density (PSD) using multi-taper spectral analysis and compared the trial-averaged PSD using a cluster-based permutation test to determine the significance of beta-band power differences between task phases.Results100% of participants and 44.8% of gray matter contacts in the amygdala (n=58) exhibited significantly decreased beta-band power during the Delay phase. During the Response phase, 90.9% of participants and 58.6% of gray matter contacts (n=58) showed significantly decreased beta-band power. We also found a difference in the proportion of amygdala contacts showing beta-band modulation between those implanted in gray vs. white matter (p=0.0035) but found no difference between contralateral vs. ipsilateral contacts (p=0.17) and male vs. female participants (p=0.34).ConclusionThis study is the first to demonstrate beta-band power decreases in the amygdala during the Delay and Response phases of a delayed reach task. These findings demonstrate that the amygdala undergoes neural modulation prior to movement initiation and during movement execution.

Note:
Funding declaration: We wish to acknowledge the generous support of the: NIH NINDS K23NS114190

Conflict of Interests: The authors report have no financial disclosures. The authors have no conflicts of interest to disclose.

Ethical Approval: .SEEG electrodes were placed in accordance with clinical care criteria, and all participants provided informed consent to be enrolled in the study (Study ID: HS-17-00544, approved by the Institutional Review Board of the University of Southern California Health Science Campus).

Keywords: Amygdala, SEEG, Stereoelectroencephalography, movement preparation, epilepsy, beta, delayed reach