Page 72 - Bladder Dysfunction in the Context of the Bladder-Brain Connection - Ilse Groenendijk.pdf

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Chapter 3
a possible somatotopy of the SMA and suggested that the cranial to caudal body is represented from anterior to posterior respectively in the SMA.24,25 Our results did not clearly demonstrate this somatotopy. In these smaller cortical body representations, the shorter distances between neighboring body parts results in lager overlap in the BOLD results. Note that this does not necessarily mean that the neural circuits for pelvic and tongue are shared in SMA, just that they are spatially closer.
The connectivity analysis showed a strong correlation between the superomedial M1 and the SMA during PFMC. Previously, it has been suggested that the SMA has a facilita- tory effect on M1 during voluntary motor tasks.4,26 Di Gangi Herms et al., compared corti- cal activation of women with stress urinary incontinence before and after pelvic floor muscle therapy (PFMT) using 3T-fMRI.23 Prior to the start of the PFMT significant clusters were found in the SMA during PFMC; after 12 weeks of daily PFMT this cluster in the SMA was not found during PFMC and activation in the M1 was smaller and more focused. Our subjects had practiced voluntary PFMC just prior to the 7T-fMRI, and in the connectivity analysis we see that the SMA was strongly connected to the M1 and other cortical and subcortical areas. The connectivity of the SMA to other brain areas during the tongue task was less pronounced than during PFMC and active clusters shown in the SMA dur- ing tongue movements were smaller (Fig 1). Voluntary tongue movement is necessary for speaking and chewing, usually a highly conditioned tasks. This indicates that the SMA is especially important in less conditioned movement control, such as PFMC. In this context, it is important to realize that cortical and subcortical activations was much more consistent among the participants during tongue movement, than during PFMC (Fig 1).
Putamen
In the present study, PFMC and tongue movement resulted in all single subjects and in the group analysis, in activation of the putamen, especially in the caudal putamen (fig 2). Although specific caudal activation of the putamen during PFMC and tongue move- ment has not been described previously, activation in the putamen as a whole has been observed before during both tasks.6-8,27 The putamen is part of the cortico-basal ganglia (BG)-thalamocortical-loop which participates in motor action selection.28
Thalamus
The last part of the cortico-BG-thalamocortical-loop is the VL/VA nuclei of the thalamus, which, in turn, project to the motor cortex.29,30 Our results showed bilateral activation in the thalamus during both tasks. In individuals and groups analyses, activation was seen possibly in the VL/VA nuclei (fig 2). Activation was not found in all single subjects, but when found, it was consistently found on the same location. The current study is the first to show these results consistently in individuals. Previous studies on PFMC and tongue movement showed activation in thalamus without specification of a thalamic subnucleus.5,6,27