Electromyography of Male Rat Perineal Musculature during Copulatory Behavior

Abstract

Electromyogram (EMG) recordings were made from the bulbospongiosus (BS) and ischiocavernosus (IC) muscles of the awake male rat in order to evaluate the roles played by these muscles in the implementation of penile intromission during a copulatory encounter. Male rats with bipolar wire electrodes implanted chronically in the BS and IC muscles were mated with sexually receptive females. Concurrent videotape recordings established a relationship between EMG and components of male rat copulatory behavior, i.e. mount, intromission and ejaculation. On EMGs recorded from the IC muscle, the initial low-amplitude phase at the initiation of each behavioral component was distinguished from the late high-amplitude phase whenever the male accomplished mounting or intromission. In the BS muscle, the late high-amplitude phase was observed only when the male accomplished intromission. Power spectrum analysis by fast Fourier transformation revealed that in the IC muscle the two phases differed at an overall range of 100–1,000 Hz. In the BS muscle, however, the spectra of the two phases differed at a specific range of 400–600 Hz. Recruitment of additional motor units would culminate in such a characteristic rise in the power spectrum. The results suggest that somatosensory inputs contingent on the intromission cause such recruitment in the BS to regulate penile cups and other movements.

Autonomic assessment of animals with spinal cord injury: tools, techniques and translation

“…316 This technique has been validated in uninjured rats as well as spinalized, anesthetized animals. 316,357 Advantages/disadvantages. Like EMG in other systems, perineal EMG is generally a terminal preparation and is conducted on anesthetized animals.…”

Serotonergic lesions of the periaqueductal gray, a primary source of serotonin to the nucleus paragigantocellularis, facilitate sexual behavior in male rats

“…The nPGi receives projections from upstream sites related to sexual behavior, including the paraventricular nucleus of the hypothalamus, medial preoptic area, and periaqueductal gray (Murphy and Hoffman, 2001; Murphy et al, 1999; Normandin and Murphy, 2008), and in turn, projects to the spinal motoneurons (pudendal motoneurons) innervating the bulbospongiosus and ischiocavernosus muscles (Hermann et al, 2003; Marson and Carson 3rd, 1999; Marson and McKenna, 1996; Tang et al, 1999), which are critical for ejaculation in male rats (Miura et al, 2001; Pescatori et al, 1993) and humans (Hsu et al, 2004; Shafik et al, 2009). …”

Long-term spinal reflex studies in awake behaving mice

“…Chronic recording of electromyographic activity (EMG) and nerve stimulation using implanted electrodes can provide information on motor activity in awake freely moving animals. The reduction in stress and other perturbations permits recording during naturally occurring motor (Belanger et al, 1996;Fortier et al, 1987;Hoffer et al, 1987;Leblond et al, 2003), respiratory (Trelease et al, 1982), sexual (Affanni et al, 2001;Miura et al, 2001), and gastrointestinal (Atobe et al, 1980;Dwinell et al, 1994) behaviors in rats, cats, primates, and other species. In addition, the ability to repeatedly or continuously stimulate nerve and/or record muscle activity for extended periods in the same animal permits powerful within-subject experimental designs.…”