ABSTRACT
Learning a motor skill involves a latent process of consolidation that develops after training to enhance the skill in the absence of any practice and crucially depends on sleep. Here, we show that this latent consolidation during sleep changes the brain representation of the motor skill by reducing overall the neocortical contributions to the representation. Functional magnetic resonance brain imaging was performed during initial training and 48 h later, at retesting, on a sequential finger movement task with training followed by either a night of regular sleep or sleep deprivation. An additional night of sleep for all subjects served to rule out unspecific effects of sleep loss at retrieval testing. Posttraining sleep, but not sleep deprivation, led to improved motor skill performance at retrieval. This sleep-dependent improvement was linked to greatly reduced brain activation in prefrontal, premotor, and primary motor cortical areas, along with a stronger involvement of left parietal cortical regions. Our findings indicate that storing a motor skill during sleep reorganizes its brain representation toward enhanced efficacy.
Subject(s)
Brain/physiology , Magnetic Resonance Imaging/methods , Memory/physiology , Psychomotor Performance/physiology , Sleep/physiology , Adolescent , Adult , Brain Mapping/methods , Female , Humans , Male , Polysomnography/methodsABSTRACT
What mechanisms allow us to direct a precise saccade to a remembered target position in space? The cerebellum has been proposed to be involved not only in motor and oculomotor control, but also in perceptual and cognitive functions. We used functional MRI (Echoplanar imaging at 1.5 T) to investigate the role of the cerebellum in the control of externally triggered and internally generated saccadic eye movements of high and low memory impact, in six healthy volunteers. Memory-guided saccades to remembered locations of 3 targets (triple-step saccades) in contrast to either central fixation or to visually guided saccades activated the cerebellar hemispheres predominantly within lobuli VI-crus I. The same areas were activated when an analogous visuospatial working memory task was contrasted to the triple-step saccades. Visually guided saccades activated the posterior vermis and the triple-step saccades, contrasted to the working memory task, activated predominantly the posterior vermis and paravermal regions. Our data confirm the primary involvement of the posterior vermis for visually-triggered saccadic eye movements and present novel evidence for a role of the cerebellar hemispheres in the mnemonic and visuospatial control of memory-guided saccades.
Subject(s)
Brain Mapping , Cerebellum/anatomy & histology , Memory/physiology , Saccades/physiology , Adult , Cerebellum/physiology , Female , Humans , Image Processing, Computer-Assisted , Magnetic Resonance Imaging , Male , Photic StimulationABSTRACT
Many cases of myoclonus-dystonia (M-D) are caused by mutations in the epsilon-sarcoglycan (SGCE) gene. We describe 3 children with a similar clinical picture of autosomal dominant M-D and an SGCE mutation in only one of them, suggesting that M-D is genetically heterogeneous.
Subject(s)
Cytoskeletal Proteins/genetics , Dystonic Disorders/genetics , Membrane Glycoproteins/genetics , Myoclonus/genetics , Adult , Alleles , Child , Child, Preschool , Chromosome Aberrations , Disease Progression , Dystonic Disorders/diagnosis , Exons/genetics , Fathers , Female , Follow-Up Studies , Genes, Dominant/genetics , Genotype , Humans , Male , Mutagenesis, Insertional/genetics , Myoclonus/diagnosis , Neurologic Examination , Psychomotor Disorders/diagnosis , Psychomotor Disorders/genetics , Sarcoglycans , Torticollis/diagnosis , Torticollis/genetics , Videotape RecordingABSTRACT
We investigated the modulation of cerebellar activation by predictive and non-predictive sequential finger movements. It is hypothesized that the prediction of desired movement sequences and adaptation to new movement parameters is mediated by the cerebellum. Using functional MRI at 1.5 T, seven normal subjects performed sequential finger to thumb opposition movements, either in predictive (repeatedly 2,3,4,5) or non-predictive (randomized) fashion at a constant frequency of 1 Hz. Performance and error rates were monitored by simultaneous recording of the finger movements. Predictive sequential finger opposition movements activated a cerebellar network including the lobuli IV-VI ipsilateral to the movements, the contralateral lobuli IV-VI, the vermis, and lobuli VIIB-VIII ipsilaterally. Non-predictive compared to predictive finger opposition movements activated a broader area within the ipsi- and contralateral anterior cerebellum, lobuli IV-VI, the vermis, and the ipsilateral lobuli VIIB-VIII. Additional activation foci were found in the contralateral lobuli VIIA and VIIB-VIII. Our study demonstrates a modulated information processing within the cerebellar network dependent on the predictability of movement sequences.
