This fMRI study investigated the human somatosensory system, especially the secondary somatosensory cortex (SII), with respect to its potential somatotopic organization. Eight subjects received electrical stimulation on their right second finger, fifth finger and hallux. Within SII, the typical finding for both fingers was a representation site within the contralateral parietal operculum roughly halfway between the lip of the lateral sulcus and its fundus, whereas the representation site of the hallux was found more medially to this position at the fundus of the lateral sulcus, near the posterior pole of the insula. Somatotopy in SII seems to be less fine-grained than in primary somatosensory cortex (SI), as, in contrast to SI, no separate representations of the two fingers in SII were observed. A similar somatotopic representation pattern between fingers and the hallux was also observed within ipsilateral SII, indicating somatotopy of contra- as well as ipsilateral SII using unilateral stimulation. Further areas exhibiting activation were found in the superior and inferior parietal lobule, in the supplementary and cingulate motor area, and in the insula.

Medial-to-lateral somatotopy is a well-established feature of the human primary somatosensory cortex (SI); however, it is unknown whether, similarly to non-human primates, a rostral-to-caudal somatotopic arrangement exists as well. Therefore, in this functional magnetic resonance imaging (fMRI) study on eight healthy human subjects, five circumscribed skin areas sequentially located on the third finger and the palm of the hand were stimulated with innocuous electrical pulses. Within area 3b of contralateral SI, successive cortical representation sites ordered in a rostral-to-caudal fashion were seen in the group analysis and in six individual subjects. The fingertip was located most rostrally, whereas the proximal parts of the finger as well as the distal palm were represented at more caudal locations. Within area 1, the group analysis revealed a similar pattern of discrete representations. However, in contrast to area 3b, the fingertip was located most caudally, whereas the more proximal parts of the finger were found to be represented rostrally within area 1. Thus, the representation pattern of area 1 appeared as a 'mirror image' of that of area 3b. In comparison to the representations of the finger and the distal palm, the proximal palm was found to be represented at a more medial position of the postcentral gyrus.

Epidemiological evidence points to prenatal viral infection being responsible for some forms of schizophrenia and autism. We hypothesized that prenatal human influenza viral infection in day 9 pregnant mice may cause changes in the levels of neuronal nitric oxide synthase (nNOS), an important molecule involved in synaptogenesis and excitotoxicity, in neonatal brains. Brains from 35- and 56-day-old mice were prepared for SDS-gel electrophoresis and Western blotting using polyclonal anti nNOS antibody. Quantification of nNOS showed time and region-dependent changes in the levels of nNOS protein. Mean rostral brain area value from prenatally infected animals showed a significant (p=0.067) increase of 147% in nNOS levels at 35 days postnatally, with an eventual 29% decrease on day 56. Middle and caudal brain areas showed reductions in nNOS in experimental mice at 35 and 56 days, with a significant 27% decrease in nNOS in the middle segment of day 56 brains (p=0.016). Significant interactions were found between group membership and brain area (Wilks lambda=0.440, F(2.9)=5.72, p=0.025); there was also a significant interaction between brain area, group and age (Wilks lambda=0.437, F(2.9)=5.79, p=0.024). These results provide further support for the notion that prenatal viral infection affects brain development adversely via the pathological involvement of nNOS expression.