The Oscillatory Dynamics of Supramodal Decision Making

Abstract

The role of rhythmic neural activity in perceptual decision making has been extensively investigated within cognitive science in humans and monkeys. The present study asks how oscillatory activity contributes to humans' supramodal perceptual decision-making process. This is done by investigating oscillatory dynamics in alpha (8-14 Hz) and beta (15-35 Hz) frequency bands as a function of stimulus features (sensory modality and frequency) and decision outcome. Previous findings have shown that decreased alpha oscillatory activity facilitates information processing, while increased alpha activity is proposed to suppress irrelevant input, influencing discrimination performance in a vibrotactile discrimination task [1]. Beta oscillatory activity is suggested to correspond to the encoding of stimulus properties and the final decision outcome, with frequency modulations recently shown to signal decision outcome [2], and power modulations proposed to reflect stimulus properties in a supramodal, context-dependent manner, and to signal decision outcome [3]. However, it remains unclear whether power modulations in the alpha and beta band flexibly establish task-relevant networks in a context- and time-dependent manner during supramodal decision making.

To investigate this, we recorded magnetoencephalography (MEG) data from 32 healthy human adults during an auditory-tactile frequency discrimination task, including both unimodal and crossmodal conditions, which facilitate supramodal coding of the relevant stimulus information. Trials were additionally either predictable, where the modality of the second stimulus was known after the first, or unpredictable. In all cases, subjects had to decide whether the frequency of the second stimulus was higher or lower than the first. We hypothesized alpha power modulations to influence discrimination performance, and beta power modulations to reflect stimulus features as working-memory content in a context-dependent, supramodal manner and additionally to reflect the decision outcome. To investigate power modulations over time, time-frequency representations of power were computed and contrasted according to the specific hypotheses. The expected results will contribute to understanding the dynamic nature of cortical oscillations in human cognition, especially in supramodal decision making. Assuming intentionality of the agent and representationalism, we aim to place the results in a broader context by discussing the possibility of empirical evidence for a cognitive representation of the working memory content and the decision outcome across species.

References

[1] S. Haegens, V. Nácher, R. Luna, R. Romo, and O. Jensen, ‘α-Oscillations in the monkey sensorimotor network influence discrimination performance by rhythmical inhibition of neuronal spiking’, Proc. Natl. Acad. Sci. U.S.A., vol. 108, no. 48, pp. 19377–19382, Nov. 2011, doi: 10.1073/pnas.1117190108.

[2] E. Rassi, J. Rodriguez-Larios, C. Gret, H. Merchant, A. Elshafei, and S. Haegens, ‘Beta-band frequency shifts signal decisions in human prefrontal cortex’. OSF, Apr. 25, 2024. doi: 10.31219/osf.io/e7ykz.

[3] S. Haegens, J. Vergara, R. Rossi-Pool, L. Lemus, and R. Romo, ‘Beta oscillations reflect supramodal information during perceptual judgment’, Proceedings of the National Academy of Sciences, vol. 114, no. 52, pp. 13810–13815, Dec. 2017, doi: 10.1073/pnas.1714633115.