Journal
EXPERIMENTAL BRAIN RESEARCH
Volume 186, Issue 1, Pages 59-66Publisher
SPRINGER
DOI: 10.1007/s00221-007-1205-8
Keywords
motor system; interhemispheric inhibition; transcranial magnetic stimulation; aging
Categories
Funding
- MRC [G0401353] Funding Source: UKRI
- Medical Research Council [G0401353] Funding Source: researchfish
- Medical Research Council [G0401353] Funding Source: Medline
Ask authors/readers for more resources
Normal aging is associated with less lateralised task-related activation of the primary motor cortices. It has been hypothesized, but not tested, that this phenomenon is mediated transcallosaly. We have used Transcranial Magnetic Stimulation to look for age-related changes in interhemispheric inhibition (IHI). Thirty healthy individuals (aged 19-78 years) were studied using a paired-pulse protocol at rest and during a low-strength isometric contraction with the right hand. The IHI targeting the right motor cortex was assessed at two intervals, 10 ms (IHI10) and 40 ms (IHI40). The corticospinal excitability of the left hemisphere was assessed by means of input-output curves constructed during voluntary construction. Age was not correlated with IHI10 or IHI40 at rest. During muscle contraction IHI tended to increase at both intervals. However, this increase in IHI during the active condition (changeIHI) was less evident with advancing age for the 40 ms interval (r = 0.444, P = 0.02); in fact a degree of disinhibition was often present. There was no correlation between age and changeIHI10. Age was negatively correlated with the area under the recruitment curve (r = -0.585, P = 0.001) and the size of the maximum MEP collected (r = -0.485, P = 0.007). ChangeIHI and measures of corticospinal excitability were not intercorrelated. In conclusion, task-related increases in interhemispheric inhibition seem to diminish with advancing age. This phenomenon is specific for long-latency IHI and may underlie the age-related bihemispheric activation seen in functional imaging studies. The mechanism underlying changes in IHI with advancing age and the association with changes in corticospinal excitability need further investigation.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available