Amazing stuff! What is the meaning of spineless! The spine is not as passive as previously believed.
So what does the spinal cord do for women? It seems, this question will be reserved for future research.
"For decades, it was thought that while the brain orchestrated male sexual behavior—arousal, courtship, and copulation—the spinal cord merely executed the final act: ejaculation. But a study ... challenges that tidy division. It reveals that a key spinal circuit is not only involved in ejaculation but also in arousal and shaping the choreography of sex, adding a surprising new dimension to our understanding of sexual behavior in mammals. ..."
"... “We were initially interested in female sexual behaviour”, ... “but it is difficult to pinpoint the moment of orgasm. In males, ejaculation is a clear and observable marker – you can literally see it in the muscle activity”. The team began with a deceptively simple question: which neurons control the muscle responsible for ejaculation? ..."
From the abstract:
"During sex, male arousal builds to the ejaculatory threshold, allowing genital sensory input to trigger ejaculation. While copulation and arousal are thought to be brain-regulated, ejaculation is a reflex controlled by a spinal circuit. In this framework, the spinal cord is assumed to be strongly inhibited by descending input until the ejaculatory threshold, playing no role in the regulation of copulatory behavior. However, this remains untested.
Here we mapped the spinal circuit controlling the bulbospongiosus muscle, essential for sperm expulsion in mice. Our findings show that bulbospongiosus muscle-motor neurons receive input from galanin-expressing neurons, which integrate genital sensory signals.
Stimulating these neurons induces bulbospongiosus activity, but responses vary with spinalization, internal state, and decrease with repeated stimulation.
Ablating galanin-positive neurons altered ejaculation latency and copulatory patterns. These results suggest that spinal circuits influence not only ejaculation but also copulation and arousal, challenging the traditional view of spinal control in copulation."
More than a reflex: how the spine shapes sex (original news release) "For decades, it was thought that while the brain orchestrated male sexual behaviour – arousal, courtship, and copulation – the spinal cord merely executed the final act: ejaculation. But a study from the Champalimaud Foundation (CF) challenges that tidy division. It reveals that a key spinal circuit is not only involved in ejaculation but also in arousal and shaping the choreography of sex, adding a surprising new dimension to our understanding of sexual behaviour in mammals."
Fig. 3: Gal+ neurons and BSM-MNs receive sensory input from the penis.
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