The somatosensory representation of the human clitoris: an fMRI study.
ABSTRACT We studied the central representation of pudendal afferents arising from the clitoral nerves in 15 healthy adult female subjects using electrical dorsal clitoral nerve stimulation and fMRI. As a control body region, we electrically stimulated the right hallux in eight subjects. In a block design experiment, we applied bilateral clitoral stimulation and unilateral (right) hallux stimulation. Activation maps were calculated for the contrasts 'electrical dorsal clitoral nerve stimulation versus rest' and 'electrical hallux stimulation versus rest'. A random-effect group analysis for the clitoral stimulation showed significant activations bilateral in the superior and inferior frontal gyri, insulae and putamen and in the postcentral, precentral and inferior parietal gyri (including the primary and secondary somatosensory cortices). No activation was found on the mesial surface of the postcentral gyrus. For the hallux, activations occurred in a similar neuronal network but the activation in the primary somatosensory cortex was localized in the inter-hemispheric fissure. The results of this study demonstrate that the central representation of pudendal afferents arising from the clitoral nerves and sensory inputs from the hallux can be studied and distinguished from each other by fMRI. From the somatotopic order described in the somatosensory homunculus one would expect for electrical clitoral nerve stimulation activation of the mesial wall of the postcentral gyrus. In contrast, we found activations on the lateral surface of the postcentral gyrus.
Article: Cyclus van seksueel genot[Show abstract] [Hide abstract]
ABSTRACT: Seks is voor velen een uitermate plezierig tijdverdrijf. Het is echter ook een bron van intens verdriet en maatschappelijke onrust. Pas relatief recent richten hersenonderzoekers zich op systematische wijze op het ontdekken van de mechanismen in het menselijke brein die aan seksueel gedrag ten grondslag liggen. In dit overzichtsartikel ontleed ik seks in drie basiselementen: zin in seks, genieten van seks, remmen van seks. Dit denkkader negeert de voortplantingsfunctie van seks, en zoomt in op de prominente rol van neuronale beloningssystemen. Ander geneugten, zoals voedselinname, gaan gepaard met dezelfde gedragselementen, en onze hersenen lijken inderdaad op een vergelijkbare manier om te gaan met eten en seks.Neuropraxis. 02/2014; 18(1):4-12.
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ABSTRACT: Neuroimaging studies have shown that changes in brain morphology often accompany chronic pain conditions. However, brain biomarkers that are sensitive and specific to chronic pelvic pain (CPP) have not yet been adequately identified. Using data from the Trans-MAPP Research Network, we examined the changes in brain morphology associated with CPP. We used a multivariate pattern classification approach to detect these changes and to identify patterns that could be used to distinguish participants with CPP from age-matched healthy controls. In particular, we used a linear support vector machine (SVM) algorithm to differentiate gray matter images from the two groups. Regions of positive SVM weight included several regions within the primary somatosensory cortex, pre-supplementary motor area, hippocampus, and amygdala were identified as important drivers of the classification with 73% overall accuracy. Thus, we have identified a preliminary classifier based on brain structure that is able to predict the presence of CPP with a good degree of predictive power. Our regional findings suggest that in individuals with CPP, greater gray matter density may be found in the identified distributed brain regions, which are consistent with some previous investigations in visceral pain syndromes. Future studies are needed to improve upon our identified preliminary classifier with integration of additional variables and to assess whether the observed differences in brain structure are unique to CPP or generalizable to other chronic pain conditions.Pain 09/2014; · 5.64 Impact Factor
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ABSTRACT: Mean diffusivity (MD) derived from diffusion tensor imaging has shown its ability to assess the microscopic structural integrity damage of gray matter in amnestic mild cognitive impairment (aMCI), a prodromal stage of Alzheimer's disease (AD). However, little is known about the small world topology networks constructed by cortical MD in cognitive disease. In this work, we measured the cortical MD in the entire brain in patients with aMCI (n = 30) and AD (n = 30) compared with cognitive-normal (CNs) controls (n = 30), and then constructed the cortical diffusivity network by using graph-theoretical analysis. Compared with CNs, patients with aMCI and AD showed abnormal small-world property of cortical diffusivity networks (higher degree of clustering and longer path length), reflecting a less optimal topological organization. Moreover, the mean degree of connections of network in aMCI patients was characterized by lower than CNs but higher than AD. In addition, 11 hub regions were identified by negative correlations between MD and the score of Montreal Cognitive Assessment after multiple regression analysis, including bilateral hippocampi and related limbic system. Among those hub regions, the connectivity of the right olfactory cortex and middle orbital gyrus to the rest of brain regions were disrupted earlier than the other 9 regions in aMCI when compared to CN. In conclusion, the change of cortical diffusivity in topological network organization, mean degree of connections, and disrupted hub regions in aMCI may serve to identify patients in the prodromal stage of AD and reflect microstructural deterioration of neurodegeneration.Journal of Alzheimer's disease: JAD 08/2014; · 3.61 Impact Factor