Monday, July 11, 2011

Underwear Models and Low Libido

Erotic or not? (from Hot Chicks with Douchebags)

Hypoactive Sexual Desire Disorder (HSDD) is a controversial diagnosis given to women who have a low (or nonexistent) libido and are distressed about it. The International Definitions Committee (a panel of 13 experts in female sexual dysfunction) from the 2nd International Consultation on Sexual Medicine in Paris defined HSDD, which has also been called Women's Sexual Interest/Desire Disorder (Basson et al., 2004), in the following fashion:
There are absent or diminished feelings of sexual interest or desire, absent sexual thoughts or fantasies and a lack of responsive desire. Motivations (here defined as reasons/incentives) for attempting to have sexual arousal are scarce or absent. The lack of interest is considered to be beyond the normative lessening with life cycle and relationship duration.
Dr. Petra Boynton has written extensively about the problematic aspects of the HSDD diagnosis and the screening tools used to assess it, as well as the medicalization of sexuality for pharmaceutical marketing purposes.

Today, however, we'll examine a recent neuroimaging study that compared a group of heterosexual women diagnosed with HSDD to a group of non-HSDD control women (Bianchi-Demicheli et al., 2011). The authors set out to determine whether there were differences in brain activity while the two groups viewed erotic male photos, relative to when they viewed non-erotic photos. The experimental stimuli were all pictures of male underwear models that were not pornographic (i.e., not Anthony Weiner shots), as shown below in Figure 1. The models were rated as erotic or non-erotic by two of the experimenters (one heterosexual male, one heterosexual female)!!

Figure 1 (Bianchi-Demicheli et al., 2011). Experimental paradigm. Procedure: each trial consisted of the following sequence: a 500 ms-fixation cross was followed by a 1,500 ms-target stimulus (here an exemplar of the erotic condition is presented). A random 1,500–4,000 ms inter-stimulus interval separated each target presentation. Participants performed a one-back task requiring the detection of occasional immediate repetitions of the same picture.

After the scanning session, participants rated each picture from 1 to 10. Scores for the non-HSDD group were 6.57 ± 1.59 (mean ± SD) for erotic and 4.45 ± 1.43 for non-erotic photos. For the HSDD group, the scores were 5.24 for erotic and 4.08 for non-erotic. Note that the standard deviations were not given for the HSDD group, nor was an analysis performed to determine whether the erotic/non-erotic difference was statistically significant. What we do know is that the non-HSDD participants reliably distinguished the two classes of subjectively rated stimuli (p=.001), and that erotic photos were rated more highly by non-HSDD than by HSDD (p=.03).

OK, so now we know that heterosexual women without HSDD rated the "erotic" male underwear models as more erotic than did the women with HSDD, but is this very surprising? And what can the brain imaging results say about low libido in HSDD beyond behavioral ratings and symptom reports? Since we already know that the women with hypoactive sexual desire aren't very thrilled by the guy in Figure 1, one would expect differences in neural activity between this group and the controls while viewing these pictures. And the differences are displayed in the figure below.

Figure 2 (Bianchi-Demicheli et al., 2011). Surface rendering of NHSDD (green) and HSDD (red) group average brain activations for the Erotic stimuli > Non-Erotic stimuli contrast. BOLD responses are shown on lateral views of the flat PALS left and right of the human brain (P < 0.01 uncorrected). Overlap of activation appears for the two groups as yellow.

The brain regions in the controls that showed greater activation for erotic vs. non-erotic pictures included high-level visual processing areas such as the fusiform and middle temporal gyri (Brodmann areas 37 and 19), and the extrastriate body area (EBA) in the lateral occipitotemporal cortex. Also showing greater activation for the sexier models were entorhinal and perirhinal regions in the medial temporal lobe (important for memory), the superior parietal lobule, the inferior frontal gyrus, and the mid-cingulate cortex. For the HSDD group, the erotic vs. non-erotic contrast revealed greater activation in some of the same regions: fusiform gyrus, superior parietal lobule, inferior frontal gyrus, and medial occipital gyrus.

The comparisons above were significant at either p < 0.05 with a family-wise error correction for multiple comparisons, or at p < 0.001 uncorrected. Once we get to the key findings, the group differences for the erotic vs. non-erotic contrast, the significance level dropped to p<0.01 uncorrected. The brain regions that met this lesser standard for the NHSDD > HSDD comparison were the intraparietal sulcus, the dorsal anterior cingulate gyrus, and the entorhinal/perirhinal region. How do the authors interpret these results?
We therefore interpret the activations in the anterior cingulate gyrus and ento/perirhinal region as reflecting a greater recruitment of motivational and associative multimodal memory processes for emotional events, respectively, presumably because of a more attentive processing of erotic stimuli in healthy participants.
. . .
Similarly, the present involvement of BA 7 [superior parietal lobule] in NHSDD participants suggests a greater recruitment of attentional and appraisal processes elicited by erotic stimuli in this group.
Conversely, areas that showed greater activation in HSDD than in NHSDD were the inferior parietal lobule, the medial occipital gyrus, and the inferior frontal gyrus.
This distinct pattern of neural changes in HSDD participants might potentially reflect different subjective interpretations (e.g., different scenario) during the processing of stimuli. Indeed, our results show that participants with HSDD differentially recruit brain areas mediating high-level cognitive functions such as social perception and visual analysis. Increased activation in the inferior frontal areas is consistent with previous findings in HSDD patients that also suggested greater activity in brain areas mediating inhibitory executive control, self-focus attention, and judgments about one's own subjective experience.
However, the inferior parietal lobule is also related to attention (including attention to another person's gaze), so one cannot conclude that the non-HSDD participants were paying greater attention to the erotic stimuli than the HSDD group. Likewise, the anterior cingulate cortex is related to a boatload of processes and functions, so one cannot conclude that greater activity there is related to greater sexual responsiveness. And really, the relatively tame photos used in this particular study were probably not all that potent in producing sexual arousal and desire in the first place, which are the core problems in hypoactive sexual desire disorder.

This wasn't the first study to report brain imaging results for women with HSDD.1 Arnow and colleagues (2009) showed erotic videos from the Sinclair Intimacy Institute (likely from The Better Sex Video Series), more specifically "erotic videos geared toward women depicting heterosexual couples engaging in various sexual activities and intercourse." Although there were problems with this particular experiment,2 the participants underwent assessments of subjective sexual arousal and peripheral sexual response (using a vaginal photoplethysmograph), as well as scans at three separate time points. Interestingly, the findings that replicated were greater activation in the entorhinal cortex and less activation in the inferior frontal gyrus for controls, relative to the HSDD group.

In the end, it is not clear how the present neuroimaging results will inform diagnosis and treatment of HSDD in women who are disturbed by their low libidos. Examining the causes of diminished sexual desire is critical, as Dr Petra tells us:
Let’s not lose sight of what are the main causes of desire problems in women – see how many of these you consider to be a ‘medical’ condition:
* Concerns over body image
* A lack of sex education or knowledge how your body works
* Not knowing what turns you on, or the inability to share what does turn you on with a partner
* Psychological or physical health problems (including sexually transmitted infections)
* Past or present sexual abuse or domestic violence
* A partner who has a sexual problem
* A partner who does not know how to turn you on effectively
* Relationship difficulties including arguments or jealousy
* Being overworked and lacking support from family and/or partner


1 An unpublished study was covered in a previous post, Media HSDD: "Hyperactive Sexual Disorder Detection".

2 As pointed out by Bianchi-Demicheli et al., these problems included a failure to match the duration of the porn and non-porn videos.


Arnow BA, Millheiser L, Garrett A, Lake Polan M, Glover GH, Hill KR, Lightbody A, Watson C, Banner L, Smart T, Buchanan T, Desmond JE. (2009). Women with hypoactive sexual desire disorder compared to normal females: a functional magnetic resonance imaging study. Neuroscience 158:484-502.

Basson R, Leiblum S, Brotto L, Derogatis L, Fourcroy J, Fugl-Meyer K, Graziottin A, Heiman JR, Laan E, Meston C, Schover L, van Lankveld J, Schultz WW. (2004). Revised definitions of women's sexual dysfunction. J Sex Med 1:40–8.

Bianchi-Demicheli, F., Cojan, Y., Waber, L., Recordon, N., Vuilleumier, P., & Ortigue, S. (2011). Neural Bases of Hypoactive Sexual Desire Disorder in Women: An Event-Related fMRI Study. The Journal of Sexual Medicine DOI: 10.1111/j.1743-6109.2011.02376.x

Aladdin as an underwear model
(from the series
Disney Heroes by David Kawena)

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At July 12, 2011 12:55 PM, Blogger Sister Y said...

I'm amazed there was any sort of significance at all. Why would anyone possibly think that women are aroused by looking at pictures of naked men? Weakest stimulus ever. The only research I'm aware of, shaky though it may be, suggests that even reportedly heterosexual women are much more aroused by viewing nude women, copulating people (of any gender combination), or even copulating animals than by viewing nude men. See also the history of Playgirl magazine.


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