Sharleen T. Sakai, PhD

Professor, Psychology

Ph.D., 1980, Michigan State University

Pub Med Search for Dr. Sakai

 Location218 Giltner Hall

Neuroscience Program Directory
Psychology Directory

Research Interests

Our research focuses on the neural networks involved in voluntary movement including goal directed reaching and sequenced movement. Our goal is understand the interface between the basal ganglia output nuclei, the cerebellum, motor cortical areas and descending systems in the production of coordinated goal directed motor activity. Disorders of the basal ganglia such as Parkinsons's disease are associated with deficits in the initiation of movements whereas damage to the cerebellum result in loss of coordination and deficits in motor learning. We have demonstrated that limited regions of the motor thalamus may be candidates for anatomical convergence by receiving projections from both the basal ganglia and cerebellum. These thalamic areas may be important sites for motor integration as they are potentially modifiable anatomical substrates for the changes that occur as a result of motor learning. In addition, we are currently collaborating with Dr. John Buford, Ohio State University, on an investigation of whether cortical input onto reticulospinal neurons is crucial for achieving goal directed reaching. Knowledge of how these important elements link to separate motor circuits will aid in our understanding of how goal directed motor behavior is achieved and provide baseline data necessary for new treatment strategies of motor disorders.

Figure 1. See description in capton
Figure 1. Purple labeled thalamocortical cells amidst both black cerebellothalamic fibers and brown pallidothalamic fibers in the owl monkey thalamus. J Comp. Neurol., 2000, 417: 164

We are extending our basic neuroscientific findings in animals to current studies in humans using fMRI to study brain networks involved in learning motor sequences. In collaboration with Drs. Rudy Bernard (Department of Physiology) and Jie Huang (Department of Radiology), we initially studied the role of force in hand movements and brain activation and are currently examining the role that different motor cortical areas play in the acquisition and learning of repetitive motor sequences. We believe that the motor systems identified in our neuroanatomical studies in non-human primates play a major role in motor learning in humans.

Figure 2. See description in caption
Figure 2. Brain activation during rhythmic hand movements under 3 types of control: passive, low force and high force (top to bottom). Cognitive, Affective & Behav. Neurosci., 2002, 2: 271-281

We have recently begun a multidisciplinary collaboration with animal behaviorist and hyena expert, Dr. Kay Holekamp, mammalogist and MSU museum curator, Dr. Barbara Lundrigan to use computed tomography (CT) to study the relationship between brain evolution and life in social environments. We are studying virtual CT endocasts of Hyena member species that vary in social complexity in order to test the hypothesis that the evolution of large brains is the result of selection pressures derived from living in complex social environments. 

Figure 3. See description in caption
Figure 3. Rendering of the CT images of an adult female spotted hyena skull showing both the skull and the brain endocast (green).