Abstract
Action selection often requires the transformation of visual information into motor plans. When visual information is transformed fast, successful response inhibition might require suppression of both the prepared muscle activity and processing of visual input. We examined how the quality of visual information influences classic fronto-basal ganglia routes associated with response selection and inhibition. Human fMRI data was collected from a stop-task with faces containing low-, high-, or all spatial frequencies. Using the drift-diffusion model for decision-making, removal of spatial frequencies was found to slow the rate of information accumulation and reduce cautiousness. On go-trials, effective connectivity analysis showed action selection to emerge through a cortico-basal ganglia network with projections from both visual and prefrontal cortex into the "direct" and "indirect" pathways of the basal ganglia. Across conditions, slowed accumulation increased connectivity from both dorsolateral prefrontal cortex and fusiform face area into the putamen. Concurrently, presupplementary motor area connectivity into putamen, and lateral occipital connectivity into subthalamic nucleus was weakened to allow lowered criteria for correct decisions. During stop trials, both visual and prefrontal cortex projected into the "hyperdirect" and "indirect" pathways of the basal ganglia. Most notably, only when a stop signal followed unfiltered faces (i.e., with the highest drift rate) the optimal model contained additional connections from prefrontal to visual cortex. Further inspection related stronger prefrontal-visual connectivity to faster inhibition times. Therefore, prefrontal to visual cortex connections might suppress the fast flow of visual input for the go task, such that the inhibition process can finish before the selection process. Together, these results provide compelling insights into how visual information interacts with fronto-basal ganglia systems, and further specify how selection and inhibition processes emerge within the basal ganglia through top-down adjustments from prefrontal-, and bottom-up evaluations from visual cortex.
Meeting abstract presented at VSS 2014