Sexually Monomorphic Maps and Dimorphic Responses in Rat Genital Cortex

Constanze Lenschow, Sean Copley, Jayne M. Gardiner, Zoe N. Talbot, Ariel Vitenzon, Michael Brecht
Current Biology. 2016-01-01; 26(1): 106-113
DOI: 10.1016/j.cub.2015.11.041

PubMed

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https://www.bordeaux-neurocampus.fr/12177

Lenschow C(1), Copley S(2), Gardiner JM(3), Talbot ZN(4), Vitenzon A(5), Brecht
M(6).

Author information:
(1)Neural Systems and Behavior, Marine Biological Laboratory, 7 MBL Street,
Woods Hole, MA 02543, USA; Bernstein Center for Computational Neuroscience
Berlin, Humboldt-Universität zu Berlin, Philippstrasse 13, Haus 6, 10115 Berlin,
Germany.
(2)Neural Systems and Behavior, Marine Biological Laboratory, 7 MBL Street,
Woods Hole, MA 02543, USA; Department of Biology, Case Western Reserve
University, 2080 Adelbert Road, Room 108, Cleveland, OH 44106, USA.
(3)Neural Systems and Behavior, Marine Biological Laboratory, 7 MBL Street,
Woods Hole, MA 02543, USA; Division of Natural Sciences, New College of Florida,
5800 Bayshore Road, Sarasota, FL 34243-2109, USA.
(4)Neural Systems and Behavior, Marine Biological Laboratory, 7 MBL Street,
Woods Hole, MA 02543, USA; Graduate Program of Neuroscience and Physiology, New
York University School of Medicine, 522 First Avenue, Smilow, Room 501,
New York, NY 10016, USA.
(5)Neural Systems and Behavior, Marine Biological Laboratory, 7 MBL Street,
Woods Hole, MA 02543, USA; Dominick P. Purpura Department of Neuroscience,
Albert Einstein College of Medicine, 1410 Pelham Parkway South, Suite 506,
Bronx, NY 10461, USA.
(6)Neural Systems and Behavior, Marine Biological Laboratory, 7 MBL Street,
Woods Hole, MA 02543, USA; Bernstein Center for Computational Neuroscience
Berlin, Humboldt-Universität zu Berlin, Philippstrasse 13, Haus 6, 10115 Berlin,
Germany. Electronic address: .

Mammalian external genitals show sexual dimorphism [1, 2] and can change size
and shape upon sexual arousal. Genitals feature prominently in the oldest pieces
of figural art [3] and phallic depictions of penises informed psychoanalytic
thought about sexuality [4, 5]. Despite this longstanding interest, the neural
representations of genitals are still poorly understood [6]. In somatosensory
cortex specifically, many studies did not detect any cortical representation of
genitals [7-9]. Studies in humans debate whether genitals are represented
displaced below the foot of the cortical body map [10-12] or whether they are
represented somatotopically [13-15]. We wondered what a high-resolution mapping
of genital representations might tell us about the sexual differentiation of the
mammalian brain. We identified genital responses in rat somatosensory cortex in
a region previously assigned as arm/leg cortex. Genital responses were more
common in males than in females. Despite such response dimorphism, we observed a
stunning anatomical monomorphism of cortical penis and clitoris input maps
revealed by cytochrome-oxidase-staining of cortical layer 4. Genital
representations were somatotopic and bilaterally symmetric, and their relative
size increased markedly during puberty. Size, shape, and erect posture give the
cortical penis representation a phallic appearance pointing to a role in
sexually aroused states. Cortical genital neurons showed unusual multi-body-part
responses and sexually dimorphic receptive fields. Specifically, genital neurons
were co-activated by distant body regions, which are touched during mounting in
the respective sex. Genital maps indicate a deep homology of penis and clitoris
representations in line with a fundamentally bi-sexual layout [16] of the
vertebrate brain.