Areas of brain activation in males and females during viewing of erotic film excerpts

Abstract

Various lines of evidence indicate that men generally experience greater sexual arousal (SA) to erotic stimuli than women. Yet, little is known regarding the neurobiological processes underlying such a gender difference. To investigate this issue, functional magnetic resonance imaging was used to compare the neural correlates of SA in 20 male and 20 female subjects. Brain activity was measured while male and female subjects were viewing erotic film excerpts. Results showed that the level of perceived SA was significantly higher in male than in female subjects. When compared to viewing emotionally neutral film excerpts, viewing erotic film excerpts was associated, for both genders, with bilateral blood oxygen level dependent (BOLD) signal increases in the anterior cingulate, medial prefrontal, orbitofrontal, insular, and occipitotemporal cortices, as well as in the amygdala and the ventral striatum. Only for the group of male subjects was there evidence of a significant activation of the thalamus and hypothalamus, a sexually dimorphic area of the brain known to play a pivotal role in physiological arousal and sexual behavior. When directly compared between genders, hypothalamic activation was found to be significantly greater in male subjects. Furthermore, for male subjects only, the magnitude of hypothalamic activation was positively correlated with reported levels of SA. These findings reveal the existence of similarities and dissimilarities in the way the brain of both genders responds to erotic stimuli. They further suggest that the greater SA generally experienced by men, when viewing erotica, may be related to the functional gender difference found here with respect to the hypothalamus.

Figure 1

Areas of significant BOLD signal increases in male subjects when brain activation associated with viewing the emotionally neutral film excerpts were subtracted from that associated with viewing the erotic film excerpts. Accompanying sagittal and coronal slices through ROIs are provided for the sake of clarity. BOLD signal changes for these slices are coregistered on top of normalized brain sections from the Montreal Neurological Institute stereotaxic space. Coordinates (x and y) are given in mm and refer to locations in the stereotaxic atlas of Talairach and Tournoux [1988]. Regions of activation are displayed as a Z score‐statistical map coded according to the color bars. Height threshold is set at P < 0.001 (z = 3.09). The neurological convention has been chosen for orientation of coronal sections in all figures i.e., left is left and right is right. A: Medial prefrontal cortex, anterior cingulate cortex, thalamus and hypothalamus. B: Orbitofrontal cortex. C: Insular cortex. D: Amygdala. E: Ventral striatum and hypothalamus. F: Occipitotemporal cortex.

Figure 2

Areas of significant BOLD signal increases in female subjects when brain activation associated with viewing the emotionally neutral film excerpts were subtracted from that associated with viewing the erotic film excerpts. As in Figure 1, height threshold is set at P < 0.001 (z = 3. 09). A: Medial prefrontal cortex, anterior cingulate cortex, thalamus and hypothalamus. B: Orbitofrontal cortex. C: Insular cortex. D: Amygdala. E: Ventral striatum. F: Occipitotemporal cortex.

Figure 3

Hypothalamic activation for the Male minus Female contrast when brain activation associated with viewing the emotionally neutral film excerpt was subtracted from that associated with viewing the erotic film excerpt. Height threshold is set at P < 0.001 (z = 3. 09).

Figure 4

Regression map showing significant positive correlation between individual BOLD signal increases in the hypothalamus and individual reported SA in male subjects. Height threshold is set at P < 0.004 (z = 2.65).