Role of the brain in the control of erection

Convergent and Divergent Structural Connectivity of Brain White Matter Network Between Patients With Erectile Dysfunction and Premature Ejaculation: A Graph Theory Analysis Study

Background

Sexual dysfunction, namely, erectile dysfunction (ED) and premature ejaculation (PE), has been found to be associated with abnormal structural connectivity in the brain. Previous studies have mainly focused on a single disorder, however, convergent and divergent structural connectivity patterns of the brain network between ED and PE remain poorly understood.

Methods

T1-weighted structural data and diffusion tensor imaging data of 28 patients with psychological ED, 28 patients with lifelong PE (LPE), and 28 healthy controls (HCs) were obtained to map the white matter (WM) brain networks. Then, the graph-theoretical method was applied to investigate the differences of network properties (small-world measures) of the WM network between patients with ED and LPE. Furthermore, nodal segregative and integrative parameters (nodal clustering coefficient and characteristic path length) were also explored between these patients.

Results

Small-world architecture of the brain networks were identified for both psychological ED and LPE groups. However, patients with ED exhibited increased average characteristic path length of the brain network when compared with patients with LPE and HCs. No significant difference was found in the average characteristic path length between patients with LPE and HCs. Moreover, increased nodal characteristic path length was found in the right middle frontal gyrus (orbital part) of patients with ED and LPE when compared with HCs. In addition, patients with ED had increased nodal characteristic path length in the right middle frontal gyrus (orbital part) when compared with patients with LPE.

Conclusion

Together, our results demonstrated that decreased integration of the right middle frontal gyrus (orbital part) might be a convergent neuropathological basis for both psychological ED and LPE. In addition, patients with ED also exhibited decreased integration in the whole WM brain network, which was not found in patients with LPE. Therefore, altered integration of the whole brain network might be the divergent structural connectivity patterns for psychological ED and LPE.

A comparative study of brain activation patterns associated with sexual arousal between males and females using 3.0-T functional magnetic resonance imaging

Background In contrast to the previous studies using a 1.5-T magnetic resonance imaging system, our study was performed on a higher magnetic field strength, 3.0 T, to gain more valuable information on the functional brain anatomy associated with visual sexual arousal for discriminating the gender difference by increasing the detection power of brain activation. Methods: Twenty-four healthy subjects consisting of 12 males and 12 females underwent functional magnetic resonance imaging examination for this study. Brain activity was measured while viewing erotic videos. Results: The predominant activation areas observed in males as compared with females included the hypothalamus, the globus pallidus, the head of the caudate nucleus, the parahippocampal gyrus, the amygdala and the septal area, whereas the predominant activation in females was observed in the anterior cingulate gyrus and the putamen. Conclusion: Our findings suggest that the brain activation patterns associated with visual sexual arousal are specific to gender. This gender difference in brain activation patterns is more remarkable at higher magnet field (3.0 T) than at 1.5 T.

A hypothesis on the relationship between tea drinking and sexual activity

As a major beverage in the world, the health benefits of drinking tea have been reported in numerous studies. The effects of green tea are mainly attributed to its polyphenol content, although caffeine, accounting for 2%-4%, appears to be related to the adaptation of mental energy by increasing alertness, attention and cognitive function, as well as elevating mood. L-Theanine, a unique amino acid in tea, has neuroprotective and mood effects. In addition, some studies on functional neuroanatomy and cerebral control of sexual function have demonstrated that the thalamus and hypothalamus play a role in emotional changes, memory and sexual behavior patterns. Our recent epidemiology research has unexpectedly found that tea drinking was positively related with sexual orgasm and sexual satisfaction in female hypertensive patients. We therefore hypothesize that long-term regular consumption of tea may play a role in sexual activity.

Brain potentials related to corpus cavernosum electromyography

The aim of this study was to elucidate the relation between electrical activity in the corpus cavernosum (CC), penile responses and brain processes. EEG potentials, penile circumference and electrical activity of the CC (CC-EMG) were recorded simultaneously while male subjects were exposed to visual sexual stimuli. The trials were sorted by the penile response of the subjects (erection, maintenance or detumescence). The corresponding EEG recordings were subjected to independent component analysis (ICA) and then correlated with CC activity. We found that CC activity was decreased in the case of erection. EEG activity was found to be correlated with CC activity in most cases at the same instant or with subsequent CC activity. EEG activity at early time points after stimulus onset (<300 ms) was found to be correlated with CC activity, indicating penile response preparation at a pre-attentive processing level. These data indicate that (i) CC activity is under the control of brain processing and (ii) autonomous input reaches the CC in fractions of a second after sexual stimulus onset. Our experimental paradigm should be used for the study of psychogenic erectile dysfunctions and could help in the development of an objective measurement of this disturbance.

Sexual dysfunction in male stroke patients: correlation between brain lesions and sexual function

OBJECTIVES

To identify the sexual function of, and effect of the location of brain lesions on sexual function in, stroke patients.

METHODS

We conducted a survey on 109 stroke patients (64.93 +/- 8.81 years) and 109 age-matched controls (64.69 +/- 8.85 years). We used a questionnaire that included the five-item version of the International Index of Erectile Function (IIEF-5) and questions about changes in sexual desire, ejaculatory function, and sexual satisfaction after a stroke. We analyzed the correlation between the results of the questionnaire and the locations of brain lesions.

RESULTS

Erectile function was significantly decreased in the stroke patient group (IIEF-5, 5.89 +/- 7.08) compared with the control group (IIEF-5, 10.67 +/- 7.10). In most patients, the frequency of intercourse and sexual desire decreased after stroke, and an ejaculation disorder accompanied intercourse, but fear regarding intercourse was not severe. A lack of sexual desire was the largest cause (59.4%) of an absence of sexual intercourse. In cases with lesions in the right cerebellum and the left basal ganglia, a significant ejaculation disorder and decrease of sexual desire were more likely to occur, respectively.

CONCLUSIONS

The sexual desire, erectile function, and ejaculatory function were impaired after stroke. A lack of sexual desire was the major cause of an absence of sexual intercourse. The specific locations of the stroke lesions, such as the left basal ganglia and right cerebellum, might be associated with sexual desire and ejaculation disorder, respectively.