Hippocampal connectivity with sensorimotor cortex during volitional finger movements. I. Laterality and relationship to motor learning.

Hippocampal interactions with the motor system are often assumed to reflect the role of memory in motor learning. Here, we examine hippocampal connectivity with sensorimotor cortex during two tasks requiring paced movements, one with a mnemonic component (sequence learning) and one without (repetitive tapping). Functional magnetic resonance imaging activity was recorded from thirteen right-handed subjects; connectivity was identified from sensorimotor cortex (SMC) correlations with psychophysiological interactions in hippocampal activity between motor and passive visual tasks. Finger movements in both motor tasks anticipated the timing of the metronome, reflecting cognitive control, yet evidence of motor learning was limited to the sequence learning task; nonetheless, hippocampal connectivity was observed during both tasks. Connectivity from corresponding regions in the left and right hippocampus overlapped extensively, with improved sensitivity resulting from their conjunctive (global) analysis. The cortical laterality of SMC connectivity depended both on the hippocampal source and the task.Functionally-defined seeds produced bilateral connectivity within the hand representation, regardless of whether finger movements were uni- or bimanual; these seeds were located midlateral within the hippocampus, whereas structural seeds were located in the posterior hippocampus and produced unilateral connectivity. Results implicate the hippocampus in volitional finger movements even in the absence of motor learning or recall.