Livne, T. | Search bioRxiv

bioRxiv2020

Spontaneous emergence of behaviorally relevant motifs in human motor cortex

Spontaneous neural activity has been shown to preserve the inter-regional structure of cortical activity evoked by a task. It is unclear, however, whether patterns of spontaneous activity within a cortical region comprise representations associated with specific behaviors or mental states. The current study investigated the hypothesis that spontaneous neural activity in human motor cortex represents motor responses that commonly occur in daily life. To test this hypothesis 15 healthy participants were scanned in a 3T fMRI scanner while performing four simple hand movements differing by their daily life relevance, and while not performing any specific task (resting-state scans). Using the task data, we identified cortical patterns in a motor ROI corresponding to the different hand movements. These task-defined patterns were compared to spontaneous cortical activity patterns in the same motor ROI. The results indicated a higher similarity of the spontaneous patterns to the most common hand movement than to the least common hand movement. This finding provides the first evidence that spontaneous activity in human cortex forms fine-scale, patterned representations associated with behaviors that frequently occur in daily life.

neuroscience↗

bioRxiv2019

Resting multivoxel activity patterns in human visual cortex are linked to patterns evoked by preferred visual stimuli

The function of spontaneous brain activity is an important issue in neuroscience. Here we test the hypothesis that patterns of spontaneous activity code representational patterns evoked by stimuli and tasks. We compared in human visual cortex multi-vertex patterns of spontaneous activity to patterns evoked by ecological visual stimuli (faces, bodies, scenes) and low-level visual features (e.g. phase-scrambled faces). Specifically, we identified regions that preferred particular stimulus categories during localizer scans (e.g. extra-striate body area for bodies), measured multi-vertex patterns for each category during event-related task scans, and then correlated over vertices these stimulus-evoked patterns to the pattern measured on each frame of resting-state scans. The mean correlation coefficient was essentially zero for all regions/stimulus categories, indicating that resting multi-vertex patterns were not biased toward particular stimulus-evoked patterns. However, the spread of correlation coefficients between stimulus-evoked and resting patterns, i.e. both positive and negative, was significantly greater for the preferred stimulus category of an ROI (e.g. body category in body-preferring ROIs). The relationship between spontaneous and stimulus-evoked multi-vertex patterns also governed the temporal correlation or functional connectivity of patterns of spontaneous activity between individual regions (pattern-based functional connectivity). Resting patterns related to an object category fluctuated preferentially between ROIs preferring the same category, and patterns related to different categories fluctuated independently within their respective preferred ROIs (e.g. body- and scene-related multi-vertex patterns within body- and scene-preferring ROIs). These results support the general proposal that spontaneous multi-vertex activity patterns are linked to stimulus-evoked patterns, consistent with a representational function for spontaneous activity.

neuroscience↗