Showing papers by "Jerome N. Sanes published in 2011"
TL;DR: The results showed that PD patients had similar adaptation rates as controls but did not demonstrate savings at both recall tests, interpreted as evidence that fronto-striatal networks have involvement in the early to late phase of motor memory formation, but not during initial learning.
Abstract: Humans learn and remember motor skills to permit adaptation to a changing environment. During adaptation, the brain develops new sensory–motor relationships that become stored in an internal model (IM) that may be retained for extended periods. How the brain learns new IMs and transforms them into long-term memory remains incompletely understood since prior work has mostly focused on the learning process. A current model suggests that basal ganglia, cerebellum, and their neocortical targets actively participate in forming new IMs but that a cerebellar cortical network would mediate automatization. However, a recent study (Marinelli et al. 2009) reported that patients with Parkinson’s disease (PD), who have basal ganglia dysfunction, had similar adaptation rates as controls but demonstrated no savings at recall tests (24 and 48 h). Here, we assessed whether a longer training session, a feature known to increase long-term retention of IM in healthy individuals, could allow PD patients to demonstrate savings. We recruited PD patients and age-matched healthy adults and used a visual-motor adaptation paradigm similar to the study by Marinelli et al. (2009), doubling the number of training trials and assessed recall after a short and a 24-h delay. We hypothesized that a longer training session would allow PD patients to develop an enhanced representation of the IM as demonstrated by savings at the recall tests. Our results showed that PD patients had similar adaptation rates as controls but did not demonstrate savings at both recall tests. We interpret these results as evidence that fronto-striatal networks have involvement in the early to late phase of motor memory formation, but not during initial learning.
78 citations
TL;DR: Effects of gaze position on PM and movement-related processes are demonstrated and new information how visual signals interact with gaze position in transforming visual inputs into motor goals is provided.
Abstract: Humans reach to and acquire objects by transforming visual targets into action commands. How the brain integrates goals specified in a visual framework to signals into a suitable framework for an action plan requires clarification whether visual input, per se, interacts with gaze position to formulate action plans. To further evaluate brain control of visual--motor integration, we assessed brain activation, using functional magnetic resonance imaging. Humans performed goal-directed movements toward visible or remembered targets while fixating gaze left or right from center. We dissociated movement planning from performance using a delayed-response task and manipulated target visibility by its availability throughout the delay or blanking it 500 ms after onset. We found strong effects of gaze orientation on brain activation during planning and interactive effects of target visibility and gaze orientation on movement-related activation during performance in parietal and premotor cortices (PM), cerebellum, and basal ganglia, with more activation for rightward gaze at a visible target and no gaze modulation for movements directed toward remembered targets. These results demonstrate effects of gaze position on PM and movement-related processes and provide new information how visual signals interact with gaze position in transforming visual inputs into motor goals.
10 citations