Many of our skilled behaviors involve not single actions but sequences of movements. Lesion and imaging studies in humans, in addition to neural recording in sub human primates have demonstrated that the medial motor areas in the frontal cortex are particularly important for the generation of motor sequences. What is less clear is the exact relation between neural activity in the different areas and the spatial and temporal features of sequence performance. Our general thesis is that the more rostral motor areas code for global aspects of sequence production such as serial order or complete sequence specification. Whereas neurons in areas with direct access to motor output such as the SMA, caudal cingulate, and motor cortex reflect sequences by changes in their directional properties. (1) To determine the extent to which the directional properties of cells in the motor cortex reflect aspects of the performance of over-learned motor sequences. The hypothesis is that cells in the motor cortex show a dynamic re-organization of directional properties during sequence production. (2) To determine the relation between neural activity in the SMA and pre-SMA and the spatial and temporal aspects of over-learned sequences. The hypothesis is that global aspects of sequence production will be more commonly coded in pre-SMA, while neural activity in SMA will reflect an interaction between the directional properties of the neurons and sequence parameters. (3) To record the neural activity in the cingulate motor areas during the performance of over-learned sequences. The hypothesis is that cingulate motor areas are an integral component of the cortical system for sequence control. The methods used will be those of standard multi-electrode recording in the target cortical areas of highly trained rhesus monkeys with appropriate instrumentation for behavioral control and monitoring. Our experimental approach differs from other attempts to examine the neural correlates of sequences in several important respects: we will use behavioral tasks which exploit the spatial dimension inherent in sequence performance and we place particular emphasis on changes in the spatial properties of the recorded neurons.
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| Ashe, James; Lungu, Ovidiu V; Basford, Alexandra T et al. (2006) Cortical control of motor sequences. Curr Opin Neurobiol 16:213-21 |
| Lu, Xiaofeng; Ashe, James (2005) Anticipatory activity in primary motor cortex codes memorized movement sequences. Neuron 45:967-73 |
