6/4/2023 0 Comments Sequential learningIt is however important to note that the data supporting this model were derived from subjects performing sequential button presses according to a previously learnt and memorized sequence. Therefore, we expected higher increases in RT when two subsequent button presses are associated with two hands. This is assumed to result in an increase in response latencies. According to this model, a transition between fingers from different hands would require at least one more node to be traversed than a transition between fingers from one hand. Here, performance in a SRTT depends on the number of nodes that have to be traversed. There is evidence that motor execution is hierarchically controlled and follows a tree-traversal process. We expected an increase in RT when the button press is associated with a switch between hands. In the present study, we were interested in learning effects of a bimanual SRTT with particular emphasis on modulations in RTs associated with switches between hands. Early experimental work provided inconsistent effects for reaction times (RTs) that are associated with switching between fingers of the same hand and between hands – a phenomenon that certainly requires further investigation in future studies. This however is an important issue in daily life situations where we use our two hands together such as in typing on a keyboard or playing a piano. Apart from the considerable knowledge regarding unilateral motor sequence learning, surprisingly little is known about the neurophysiological mechanisms of bilateral engagement of hands in a sequential manner. Here, IHI between M1 cortices is known to play an important role for intermanual transfer. A major focus in learning- related studies assessing performance changes during SRTT is whether skills acquired at one hand would be transferred to the other hand. It has also been suggested that interhemispheric inhibition (IHI) is involved in simple and complex sequences of finger movements by suppressing the activity of the contralateral hemisphere –. Studies probing for neural correlates of the production of sequential movements identified key areas such as motor-related cortical areas including the primary motor cortex, , prefrontal areas, , the cerebellum and occasionally, the basal ganglia. In the past, numerous studies have examined the mechanisms underlying unilateral motor skill learning using a serial reaction time task (SRTT), typically revealing a learning effect after several repetitions when compared to a random sequence (for review see ). Thus, knowledge about errors and effects typically found in bimanual performance and understanding their respective mechanisms not only contributes to theorizing in human motor control, but has major implications for practical applications, e.g. Many tasks in our daily life demand not only to use different fingers of one hand in a serial fashion, but also alternate from one hand to the other. This study provides evidence for modulations of switch costs during bimanual sequence learning, a finding that might have important implications for theories of bimanual coordination and learning. Hand switch costs significantly decreased during the time course of learning, and remained stable over a time of approximately two weeks. This increase in RT was defined as switch costs. Furthermore, RT to a button press showed an increase when the previous button press was associated with another hand as opposed to the same hand. We found that bimanual SRTT resulted in a global decrease in RT during the time course of learning that persisted for at least two weeks. Two outcome measures were investigated: (a) global sequence learning as defined by the time needed to complete a 15-letter SRTT sequence and (b) changes in hand switch costs across learning. Each letter was assigned a specific button press with one of four fingers. The bimanual SRTT consisted of sequential button presses either with the left or right index- and middle-finger to a series of visual letters displayed on a computer screen. Here, we investigated performance in a bimanual serial reaction time task (SRTT) with particular emphasis on learning-related changes in reaction time (RT) for consecutive button presses for homologous index- and middle fingers. Many tasks in our daily life demand not only the use of different fingers of one hand in a serial fashion, but also to alternate from one hand to the other.
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