The present grants of the PI of this collaborative project (P. Strick) are directed primarily for connectivity studies and functional mapping in the monkey brain. Subsequent to the development of human functional imaging with magnetic resonance in 1992, an active collaborative effort has developed on human brain mapping, utilizing the 4 Tesla instrument supported as a BTRR at the University of Minnesota. These human studies are direct extensions of the monkey work and currently focus on 1) identification and somatotopic organization of premotor areas especially in the frontal lobe of the human brain and 2) cognitive role of the cerebellum in the human brain. Abstracts have been presented in 1996 ISMRM and Brain Map meetings on the first topic, and articles in Science magazine has already been published in previous years on the second subject. Classically, the primary motor cortex has been viewed as the """"""""upper motoneuron"""""""" or the """"""""final common pathway"""""""" for the central generation of movement. According to this concept, the primary motor cortex was the main source of descending commands for voluntary movement. The basal ganglia, cerebellum and cortical areas in the parietal and frontal lobe were thought to influence these commands largely through direct or indirect projections to the primary motor cortex. The results of our recent studies have led us to challenge this concept. We have shown that there are at least 6 premotor areas in the frontal lobe. Each premotor area is somatotopically organized and contains largely separate regions for the control of arm and leg movements. Perhaps more importantly, our results indicate that each of these premotor areas has substantial direct projections to the spinal cord. Furthermore, our data suggests that the corticospinal projections from the premotor areas are involved in the control of both distal and proximal arm movements. These observations raise the possibility that each premotor area is an independent source of central commands for the generation of limb movement. While the many of these areas are identified in the monkey brain, similar exhaustive anatomical identification in the human brain does not exist, especially the six premotor areas that were identified in the frontal cortex of the monkey brain. This issue is currently being pursued as a collaborative project at the high field national research resource at the CMRR, taking advantage of the recent developments in functional magnetic resonance imaging and the advantages of high magnetic fields in cortical mapping. The specific hypothesis tested is that the general cortical region area often referred to as Broca's area (including and near parts of Brodmann's areas BA44, BA45) may significantly overlap with and may be the location of a ventral lateral premotor area (PMv) described in monkey studies . To test this and to discriminate between functional areas, subjects are asked to perform several motor tasks and a covert speaking task. These tasks are: (I) random tongue movement, (II) toe movement, (III) complex instruction guided finger-tapping, (IV) copying of displayed hand shapes and (V) covert speaking task. Task V requires phoneme based word generation. Preliminary results demonstrate that the frontal lobe of humans contains a region that is comparable to the PMv of monkeys and this area lies in a ventral inferior part of BA6, BA44 and BA45. In addition, these studies are being extended to deaf subjects who are native users of American sign language (ASL) where the Broca's areas language and motor functions are further examined. The advantage in this approach is the similarity of the language and motor tasks that can be designed. In previous years we have accumulated a large set of data which we are in the process of analyzing.
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