This project contains links to code and data for the manuscript *"Rhythmic interactions between the mediodorsal thalamus and prefrontal cortex precede human visual perception"*. Download the preprint here: https://www.biorxiv.org/content/10.1101/2022.02.07.479362v1.abstract ---------- **Abstract** The thalamus is much more than a simple sensory relay. High-order thalamic nuclei, such as the mediodorsal thalamus, exert a profound influence over animal cognition. However, given the difficulty of directly recording from the thalamus in humans, next-to-nothing is known about thalamic and thalamocortical contributions to human cognition. To address this, we analysed simultaneously-recorded thalamic iEEG and whole-head MEG in six patients (plus MEG recordings from twelve healthy controls) as they completed a visual detection task. We observed that both the phase of ongoing mediodorsal thalamic and prefrontal alpha activity was predictive of perceptual performance. Critically however, mediodorsal thalamic activity mediated prefrontal contributions to perceptual performance. These results suggest that it is thalamocortical interactions, rather than cortical activity alone, that is predictive of upcoming perceptual performance and, more generally, highlights the importance of accounting for the thalamus when theorising about cortical contributions to human cognition. ----------