Thalamus and penile erection

Abstract

Penile erection is a complex neurovascular event. The neuronal system involved is often divided into a spinal (generator) and supraspinal (controller) network. Little is known about the supraspinal control. The recent finding of changes in penile erection following deep brain stimulation of the thalamus in two patients has raised the question as to what extent the thalamus is involved in erectile function. The thalamus has generally been regarded as a group of relay nuclei that served as a 'gate' for sexual information from the spinal cord towards higher centres. Recent evidence, however, suggests a more integrated regulatory function. Our review of the literature from 1960 until 2003 revealed 13 reports describing original data (preclinical and clinical). Various thalamic regions, varying from the midline thalamus to the posterior thalamus, have been reported to be activated during erection. The majority of the reports, however, showed that mainly the mediodorsal (MD) nucleus and the centromedian-parafascicular nucleus (Cm-Pf complex) are involved in penile erection. MD is the second largest nuclear aggregation located within the medial part of the thalamus. Anatomically, the MD is closely related to the Cm-Pf complex. The Cm-Pf complex is one of the most important relay stations in which the anterolateral spinothalamic pathway is further processed. This pathway is thought to transmit peripheral sexual sensations. On the whole, the present data on the role of the thalamus in erection are far from complete and future experiments are required to delineate its involvement.

High field fMRI reveals thalamocortical integration of segregated cognitive and emotional processing in mediodorsal and intralaminar thalamic nuclei

“…Therefore the MD is not considered a specific but rather a supportive sexual core region. This would explain the observation of sexual dysfunction after MD lesions and underlines the importance of the affective component during a multidimensional processing of sexual arousal (Redouté et al, 2000; Temel et al, 2004). …”

“…It was shown to be part of the ascending reticulo–thalamo–cortical activating system (Moruzzi and Magoun, 1949; Isaacson and Tanaka, 1986; Cornwall and Phillipson, 1988b) and to be involved in sexual arousal and erection in rats and gerbils (Heeb and Yahr, 1996, 2001; Coolen et al, 1997, 2003a,b; Veening and Coolen, 1998; Temel et al, 2004). …”

Long-term outcome of thalamic deep brain stimulation in two patients with Tourette syndrome

“…Effects on sexual functioning including an increased sexual drive in case 2 at 8 months after surgery have been described previously in detail 17 18. Sexual functioning (see table 3) was measured by the International Index of Erectile Function (IIEF) including five domains 19…”

Neuroimaging and Sexual Behavior: Identification of Regional and Functional Differences

“…The mediodorsal nucleus of the thalamus, associated with mechanisms of reward [19], was shown to be activated in humans exposed to sexual cues [50]. Deep brain stimulation of the mediodorsal nucleus was also found to elicit penile erection [51,52]. As a relay in the feedback loops of the basal ganglia to prefrontal and premotor cortex, it would be expected that the thalamus plays a major role in sexual arousal since the basal ganglia are often found to be activated in response to sexual stimuli.…”