Making accurate decisions often involves the integration of current as well as past evidence. How the brain achieves this is largely unknown, but the subthalamic nucleus (STN) has been shown to represent immediate conflict in evidence, specifically via theta and beta oscillations. Here we examine the neural correlates of evidence conflict and integration during sequential decision making.
Patients implanted with electrodes for deep brain stimulation (DBS) and age-matched healthy controls performed an expanded judgement task, in which they were free to choose how much evidence (cues) to sample before making a decision. Magnetoencephalography (MEG) and STN local field potentials (in patients) were recorded.
We found that beta oscillations signalled conflict between cues within a sequence. Specifically, beta power in the STN and cortex first decreased and then increased following cues in the sequence that differed from previous cues. Cortical activity preceded STN activity and premotor cortical-STN coherence was increased in the beta band following the onset of a conflicting cue.
Furthermore, the conflict signal in the STN was more persistent over time. These results extend our understanding of cortico-subcortical dynamics of conflict processing, and do so in a context where evidence must be accumulated in discrete steps, much like in real life.
bioRxiv Subject Collection: Neuroscience