Traditionally the cerebellum has been thought of as purely motoric. Previous research with paired-pulse (cerebellar-primary motor cortex [M1]) transcranial magnetic stimulation (TMS) has illustrated that when a muscle is at rest the cerebellum has an inhibitory influence on the motor cortex (Pinto & Chen, 2001); the inhibition is strong at an interstimulus interval (ISI) of 5 ms, and diminishes as the ISI increases. An active muscle, in contrast, exhibits little or no inhibition. Intriguingly, however, there is growing recognition that the cerebellum also plays a role in cognition (Molinari et al., 2002), including motor imagery (Luft et al., 1998; Lotze et al., 1999). We used paired-pulse TMS to explore the connectivity of the cerebellum with M1 during imagery. Corticospinal excitability was measured in the first dorsal interosseous (FDI) of the right hand. Stimulation intensities of 5% below active motor threshold for pyramidal tract activation (conditioning stimulus, cerebellum) and 20% above resting motor threshold for FDI (test stimulus, M1) were used. Two ISIs were selected based on preliminary testing in which we obtained a clear inhibition of excitability in the resting FDI at an ISI of 5 ms, and no inhibition at 10 ms. Participants performed imagery of a motor task (kinesthetic imagery of their right index finger moving) and a static visual task (imagine standing in front of and looking at their house). Each imagery task was performed three times: in a block with a 5 ms ISI, a block with a 10 ms ISI, and a block with the test stimulus only. The data indicate that the pattern of temporal modulation found during rest is also found during the cognitive task of imagery: relative to the test pulse alone, MEPs were inhibited only when stimulation delivered with a 5 ms ISI. Thus, the connectivity of the cerebellum to the motor cortex during kinesthetic imagery appears to be similar to that present during rest rather than action.
Fourkas A.D., Avenanti A., Molinari M., Leggio M.G., Aglioti S.M. (2006). Cerebellar-motor connectivity during imagery: a paired-pulse transcranial magnetic stimulation study. s.l : Federation of European Neurosciences.
Cerebellar-motor connectivity during imagery: a paired-pulse transcranial magnetic stimulation study
AVENANTI, ALESSIO;
2006
Abstract
Traditionally the cerebellum has been thought of as purely motoric. Previous research with paired-pulse (cerebellar-primary motor cortex [M1]) transcranial magnetic stimulation (TMS) has illustrated that when a muscle is at rest the cerebellum has an inhibitory influence on the motor cortex (Pinto & Chen, 2001); the inhibition is strong at an interstimulus interval (ISI) of 5 ms, and diminishes as the ISI increases. An active muscle, in contrast, exhibits little or no inhibition. Intriguingly, however, there is growing recognition that the cerebellum also plays a role in cognition (Molinari et al., 2002), including motor imagery (Luft et al., 1998; Lotze et al., 1999). We used paired-pulse TMS to explore the connectivity of the cerebellum with M1 during imagery. Corticospinal excitability was measured in the first dorsal interosseous (FDI) of the right hand. Stimulation intensities of 5% below active motor threshold for pyramidal tract activation (conditioning stimulus, cerebellum) and 20% above resting motor threshold for FDI (test stimulus, M1) were used. Two ISIs were selected based on preliminary testing in which we obtained a clear inhibition of excitability in the resting FDI at an ISI of 5 ms, and no inhibition at 10 ms. Participants performed imagery of a motor task (kinesthetic imagery of their right index finger moving) and a static visual task (imagine standing in front of and looking at their house). Each imagery task was performed three times: in a block with a 5 ms ISI, a block with a 10 ms ISI, and a block with the test stimulus only. The data indicate that the pattern of temporal modulation found during rest is also found during the cognitive task of imagery: relative to the test pulse alone, MEPs were inhibited only when stimulation delivered with a 5 ms ISI. Thus, the connectivity of the cerebellum to the motor cortex during kinesthetic imagery appears to be similar to that present during rest rather than action.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
