A team from several departments at the Medical College of Wisconcin, USA, have just published research that they conducted on the cerebral cortical processing of information relayed via visceral afferents.
This poorly understood subject was studied by determining and comparing cortical activity caused by various levels of rectal distension in healthy male and female subjects.
A total of 28 healthy volunteers (13 male, 15 female), aged between 20 and 44 years, were studied with a paradigm-driven functional magnetic resonance imaging (fMRI) technique.
The technique was applied during barostat-controlled rectal distension at perception threshold, and 10 mmHg below and above this threshold.
Male subjects were found to show localized clusters of fMRI activity, primarily in the sensory and parietooccipital regions.
In female volunteers, there was also activity present in the anterior cingulate and insular regions.
| Differences in cortical activation topography during rectal distension between genders.
| American Journal of Physiology - Gastrointestinal & Liver Physiology |
A progressive increase in maximum percent fMRI signal change and total volume of cortical activity was associated with the intensity of rectal distension pressure in both genders.
Regions of cortical activity for below-threshold stimuli showed less substantial signal intensity and volume, than responses for threshold and above-threshold stimuli.
Volume of cortical activity during rectal distension in women was significantly higher than that for men for all distensions.
The study group suggests that their findings show that there are substantial differences in female cortical activation topography during rectal distension, compared with males.
They also claim that their study shows that intensity and volume of registered cortical activity due to rectal stimulation are directly related to stimulus strength. In addition, rectal stimulation below perception level is registered in the cerebral cortex.