Feature-specific patterns of attention and functional connectivity in human visual cortex

Abstract

Attending to different features of a scene can alter the responses of neurons in early- and mid- level visual areas but the nature of this change depends on both the (top down) attentional task and the (bottom up) visual stimulus. One outstanding question is the spatial scale at which cortex is modulated by attention to low-level stimulus features such as shape, contrast and orientation. It is unclear whether the recruitment of neurons to particular tasks occurs at an area level or at the level of intra-areal sub-populations, or whether the critical factor is a change in the way that areas communicate with each other. Here we use functional magnetic resonance imaging (fMRI) and psychophysics, to ask how areas known to be involved in processing different visual features (orientation, contrast and shape) are modulated as participants switch between tasks based on those features while the visual stimulus itself is effectively constant. At a univariate level, we find almost no feature-specific bottom-up or top-down responses in the areas we examine. However, multivariate analyses reveal a complex pattern of voxel-level modulation driven by attentional task. Connectivity analyses also demonstrate flexible and selective patterns of connectivity between early visual areas as a function of attentional focus. Overall, we find that attention alters the sensitivity and connectivity of neuronal subpopulations within individual early visual areas but, surprisingly, not the univariate response amplitudes of the areas themselves.

V1 Projection Zone Signals in Human Macular Degeneration Depend on Task Despite Absence of Visual Stimulus

“…It is also not yet clear whether feedback signals observed in this study are common with those reported in visual attention studies because the task is different and the effect of attention on visual areas along the hierarchy was variable across studies. [52][53][54][55][56][57] Previous studies suggested preserved retinotopic organization in V1 of JMD patients 58 and congenital bilateral anophthalmia. 59 Consistent with this idea, the task-dependent V1 LPZ ll responses of JMD patients observed in this study suggest preservation rather than remapping of retinotopy.…”

The role of task on the human brain’s responses to, and representation of, visual regularity defined by reflection and rotation

“…Classification accuracy was then averaged across validation sets, for each condition, and across participants, for each ROI and task, separately. The resulting accuracies were then tested against chance performance using one-sample tests (Kriegeskorte et al, 2007; Wailes-Newson et al, 2019) for each ROI separately, with ɑ-level Bonferroni corrected for effects of stimulus category (the higher the classification accuracy, the more distinct the representations of different regular patterns are for a specific area in the visual cortex). Performance of each independent ROI classifier is measured by percent correct classification (accuracy), with the null hypothesis of the classifier to perform at chance level (e.g., 50% for a two-way classification routine).…”