SEMINAR: Psychology postgrad seminar

Previous research, in humans, has documented a tendency towards synchronous and symmetrical movements in humans, referred to as bimanual coupling. Communication across the corpus callosum is critical to bimanual coupling. However, the corpus callosum supports multiple neural interactions and it is not yet clear which of these contribute to bimanual coupling. Transcranial magnetic stimulation (TMS) may be used to investigate neural interactions and to document the effects of circuits which facilitate or inhibit the output cells of the motor cortex. TMS research has identified several neural interactions which appear to be transmitted through the corpus callosum and may therefore contribute to bimanual coupling. These neural interactions include interhemispheric inhibition (IHI) and interhemispheric facilitation (IHF).

The proposed research will investigate the role of IHI and IHF in bimanual coupling using a bimanual force production task, which requires subjects to simultaneously pinch together the thumb and index finger of each hand to produce equal forces (coupling their hands) or unequal forces (decoupling their hands). By measuring IHI or IHF in the motor preparation period of this task, the proposed research will determine whether the strength of IHI or IHF is altered by differences in the bimanual coupling demands of the task. Subsequent studies will alter the TMS parameters to more comprehensively evaluate the role of IHI or IHF in bimanual coupling and determine the stages of motor planning affected by IHI or IHF. Later studies will investigate the relationship between IHI or IHF and bimanual coupling by manipulating conditions known to influence the strength of bimanual coupling and observing whether IHI or IHF varies in ways consistent with their proposed role in bimanual coupling.