Ph.D., University of Pennsylvania
Dr. Strick's research focuses on three major issues:
1) The Control of Voluntary Movement by the Cerebral Cortex. In the past, the Primary Motor Cortex (M1) was viewed as the main cortical area that projects to the spinal cord and generates movement. Other brain regions were thought to influence motor output solely by gaining access to M1. Experiments in Dr. Strick's laboratory have led to major modifications in this view. His results show that the frontal lobe contains at least 6 'premotor' areas. Each of these premotor areas projects directly to M1 and to the spinal cord. In fact, some of the neurons in the premotor areas are like neurons in M1 in having direct connections with spinal motoneurons that control muscles. Thus, the premotor areas have direct access to the spinal cord mechanisms responsible for volitional movement. Dr. Strick's laboratory is presently using anatomical, physiological and functional imaging techniques to determine how each of the cortical motor areas differentially contributes to the generation and control of voluntary movement. His laboratory also is investigating the role of the premotor areas in the recovery of motor function that can occur following damage to M1 or its connections (as in spinal cord injury or strokes). Present evidence suggests that the premotor areas are important for the guidance of limb movements, the proper sequencing of motor tasks and the acquisition and retention of motor skills. Indeed, damage to the premotor areas in humans leads to a syndrome termed "apraxia" in which patients are unable to perform skilled motor tasks like dressing, shaving and using tools.
2) Functional Organization of the Basal Ganglia and Cerebellum. Part of the neural substrate for the central control of movement is formed by multiple 'loops' between the cerebral cortex and two subcortical centers, the basal ganglia and cerebellum. These circuits have long been regarded as contributing to the planning, initiation and regulation of limb movement. Recently, Dr. Strick's laboratory has provided evidence that basal ganglia and cerebellar outputs also are involved in a variety of non-motor functions. His results suggest that concepts about the function of these subcortical centers should be broadened to include their involvement in cognitive processes such as working memory, rule-based learning, switching attention, visual perception and the planning of future behavior. Furthermore, Dr. Strick's results support the growing evidence that dysfunction of the basal ganglia and/or cerebellum may be partly responsible for the symptoms of behavioral disorders such as schizophrenia, obsessive-compulsive disorder, attention deficit hyperactivity disorder, depression and autism.
3) Unraveling the Circuitry of the Central Nervous System. One of the major challenges of modern neuroscience is to define the complex pattern of neural connections that is the substrate for behavior. Dr. Strick's laboratory has developed a unique approach to this problem which employs transneuronal transport of neurotropic viruses. The viruses he uses are transported selectively between interconnected neurons. These novel tracers make it possible to define the elaborate matrix of interconnections which characterizes the central nervous system of primates. Furthermore, these studies provide novel important insights into the movement of viruses in the brain.