METHODS (CON’T) Subjects: Two adult male rhesus monkeys (SDM71 & SDM74), selected from a parent study examining unimanual skills before and after brain insult. They were housed and maintained in a United States Department of Agriculture (USDA) approved and inspected facility. Protocols were approved by the University of South Dakota Institutional Animal Care and Use Committee and performed according to USDA, National Institutes of Health and Society. Lesions (Fig. 2): Schematics of the intended lesions (actual lesions are currently being reconstructed). When performance stabilized, subjects underwent surgical aspiration contralateral to the preferred limb. The arm representation of primary motor cortex (M1) and lateral premotor cortex (LPMC) were targeted in both subjects, however the arm representation of the primary somatosensory cortex (S1) was also lesioned in SDM71. Testing resumed one week later. Post-lesion, SDM74 was tested on the bilateral task and unilateral tasks (modified dexterity board or mDB – Pizzimenti et al. 2007, modified movement assessment panel or mMAP – Darling et al. 2006) at weekly intervals for two months, then every other week. SDM71 also received post-lesion “therapy” beginning two weeks after the lesion. The “therapy” involved retrieving food pellets with only the contralesional hand from the flat surface of a modified dexterity board (Pizzimenti et al. 2007). Behavioral Coding: Videos were analyzed using SIMI motion analysis software. A rater viewed all trials, frame-by-frame, marking those in which an event occurred. Events: start of push, drawer/raisin exiting the chamber (to allow grasping), contact with raisin . Paired attempts: a push/grab or grab/push sequence. Unpaired attempts: an isolated push or grab. For paired attempts, the difference of pushing and grasping times was calculated. Positive values indicate the correct order (push then grasp); negative is the incorrect order (grasp then push). 293.9 Interlimb coordination during learning and post-lesion recovery of bimanual skill in rhesus monkeys. RESULTS CONT’D Fig 2: Schematics of the intended lesions Fig 1: Experimenter demonstrating the drawer task. S. M. Hynes 1 , L. B. Bartel 1 , W. G. Darling 1 , M. A. Pizzimenti 2 , J. Ge 3 , K. S. Stilwell-MorecraftT 3 , R. J. Morecraft 3 1 Integrative Phys., 2 Anat. and Cell Biol., Univ. of Iowa, Iowa City, IA; 3 Div. of Basic Biomed. Sci., Univ. of South Dakota, Vermillion, SD References: Krause et al. (2010) Neuroimage 52:245; Darling et al. (2010) Exp Brain Res 202:529; Pizzimenti et al. (2007) J Neurophysiol 98:1015 Support: NIH Grant NS046367 BACKGROUND The present study examined subjects learning to coordinate gross and fine motor skills and recovery of these abilities after lesions to sensorimotor cortex. This entailed pushing a spring-loaded drawer open with one hand while retrieving a reward from the drawer using the other hand. Two adult male rhesus monkeys underwent testing. After skill acquisition was measured, surgical ablation of arm areas of lateral sensorimotor cortex were used to model the effects of lateral hemispheric brain injury (which spares mesial sensorimotor cortex) on bimanual coordination. Subject (SDM74) generally had decreased trial duration and increased pushing forces during learning and quickly regained that ability after lesioning. Yet SDM71 would routinely push the drawer and then break contact with the drawer while leaning sideways to grab the treat. Usually the drawer shut, requiring repeated attempts, which occurred in rapid succession. These qualitative differences, coupled with inconsistent peak force and push durations, render the interpretation of SMD71's skill proficiency difficult. We therefore devised a new measure to examine interlimb coordination and those results are reported in the current poster. HYPOTHESES • Temporal coordination will improve during learning, worsen post-lesion and return during recovery. • A lesion involving primary somatosensory cortex will produce greater deficits and slower recovery than a lesion involving only frontal lobe motor areas. METHODS Device: The drawer is rigged with interchangeable springs which can alter the force needed to open it. The drawer can be rotated 180 0 to test coordination of pushing and fine motor control in both hands. Sessions: Every 1-2 weeks subjects were food deprived for 18-24 hours beforehand, ensuring high motivation. Monkeys freely sat upright before the chamber while conducting this task. In the first session an investigator modeled the task (Fig. 1), then the monkeys attempted it without a spring. Then a light (spring #1) and stiffer spring (#2) were added. Later on, the spring compression was further adjusted by turning a set screw, requiring even higher forces to open the drawer, a protocol change SDM71 experienced. Fig 3: Previously reported peak force (above) and trial duration (below) graphs for the preferred hand, shown for comparative purposes. DISCUSSION SDM74’s intervals appear more consistent during recovery than they were before cortical insult. Improvements beyond pre-lesion skill have occurred in monkeys in the from the parent study on unimanual tasks (Darling et al. 2010, Darling et al. submitted manuscript) Previously, any evidence of skill mastery was obscured by his erratic force production and durations (fig.3). SDM71’s pre-lesion trials, when pushing with the preferred hand, were a bit irregular but improved slightly. There is evidence of learning, although it is not dramatic. Extending the lesion to include S1 may initially lead to more severe deficits. The magnitude and variability of SDM71’s push/grasp intervals were more pronounced in both hands post-lesion. He also tended to attempt to grasp for the raisin before he pushed the drawer open. Moreover, SDM71’s recovery seems incomplete, or perhaps much slower. Occasionally, he still executed his hand movement in the wrong order, especially when grasping with the contralesional hand. If SDM71 had not participated in a therapeutic intervention, his performance may have been worse. However remote, at this point we cannot rule out the possibility that this unimanual therapy could have unexpected, negative affects that are exaggerating his deficits in bilateral movements. CONCLUSIONS  For both monkeys, push/grab intervals decreased with learning and re-stabilized with recovery, supporting our first hypothesis.  The severity and persistence of SDM71’s deficits suggest primary somatosensory cortex (S1) may play a key role in executing precise interlimb coordination. Using MEG Krause et. al. (2010) found increased S1 activity in drummers, but not in non- musicians, during an auditory-motor synchronization task. MEG suggests the cerebello-thalamo-cortical network is responsible for sensorimotor synchronization in the drummers. The same may be true for touch and proprioception during bilateral movements. RESULTS