Neural evidence of a role for spatial response selection in the learning of spatial sequences

Despite over 20 years of behavioral research, considerable disagreement remains regarding the locus of the cognitive mechanisms (e.g., stimulus encoding, response selection or response production) responsible for the acquisition and expression of learned sequences. Functional neuroimaging may prove invaluable for resolving this controversy. The cortical mechanisms underlying spatial response selection (i.e., right dorsal prefrontal, dorsal premotor and superior parietal cortices) are well known. These regions as well as supplementary motor area, striatum and the hippocampus have also been implicated in sequence learning. This neural overlap lends support for the hypothesis that spatial response selection is involved in learning spatial sequences; however, these experimental factors have not been investigated in the same experiment so the extent of neural overlap is debatable. The present study investigates the role of spatial response selection in sequence learning during the performance of the serial reaction time task. We orthogonally manipulated spatial sequence learning and spatial response-selection difficulty to precisely identify the neural overlap of these cognitive systems. Results demonstrate near complete overlap in regions affected by the spatial response selection and spatial sequence learning manipulations. Only right dorsal prefrontal cortex was selectively influenced by the response selection difficulty manipulation. These findings emphasize the importance of spatial response selection for successful spatial sequence learning.