The genitals and gluteal skin are represented lateral to the foot in anterior parietal somatosensory cortex of macaques

Abstract

Detailed electrophysiological maps of the representations of trunk and adjacent body parts in area 3b and area 1 of somatosensory cortex were obtained in three macaque monkeys (Macaca mulatta and Macaca radiata) of either sex. A total of 211 microelectrode penetrations 250-300 microm apart resulted in 1,190 recording sites. During penetrations deep into the posterior bank of the central sulcus, recordings were made every 300 microm to depths of 6-7 mm until sites unresponsive to somatic stimuli were reached. Cortex was later cut parasagittally and sections were stained for cytochrome oxidase (CO) or Nissl substance. Contrary to expectations from earlier reports, the genitalia were represented lateral to the representations of the foot in cortex along the area 3b/1 border. The gluteal skin including the gluteal pads and the base of the tail were also represented in this section of cortex. Only a small region of cortex was devoted to the genitalia, and neurons in this cortex had receptive fields that were large and typically included skin of the inner thigh and belly. The lower, middle and upper trunk were represented more laterally, followed by the neck, upper head and arm. The receptive fields on the trunk were roughly the same size as those for the middle and lower trunk and slightly smaller on the upper trunk.

Prevalence of Phantom Breast Pain and Sensation Among Postmastectomy Patients Suffering from Breast Cancer: A Prospective Study

“…found that premastectomy pain was related to both PBS at all timepoints studied (3 weeks, 1 year and 6 years following mastectomy), whereas PBP was related to premastectomy pain at 3 weeks only. Rothemund et al . also found that chronic premastectomy pain resulted in higher prevalence of PBS.…”

“…In our study, we did not find any relationship between premastectomy pain with PBP or PBS, which is similar to the results of Markopoulos et al 40 However, Krøner et al 1,2 found that premastectomy pain was related to both PBS at all timepoints studied (3 weeks, 1 year and 6 years following mastectomy), whereas PBP was related to premastectomy pain at 3 weeks only. Rothemund et al 41 also found that chronic premastectomy pain resulted in higher prevalence of PBS.…”

Sexually selected size differences and conserved sexual monomorphism of genital cortex

“…Similar findings in the human somatosensory cortex are still controversially discussed. Novel imaging studies (Kell, von Kriegstein, Rösler, Kleinschmidt, & Laufs, ) and the above mentioned recordings in monkeys (Rothemund et al, ) suggest a genital representation in the region of the hip and leg representation, whereas other imaging studies (Komisaruk et al ) and the initial recordings identified it at the medial wall, below the foot representation (Penfield & Rasmussen, ). Our findings corroborate the idea that somatotopy applies to genital cortex.…”

The Sensory Cortical Representation of the Human Penis: Revisiting Somatotopy in the Male Homunculus

“…This result, together with that of an orderly somatotopic sequence, is in good agreement with studies on nonhuman primates. In chimpanzees (Woolsey, 1964) and macaques (Rothemund et al, 2002), the genital representation also clearly lies on the convexity of the hemisphere. In the latter study, the authors localized the sensory focus for the genitals to the border between Brodmann areas 3b and 1, as we did in humans.…”