The HOT or NOT "Social Attention" Study

OR, "why men are much greater consumers of pornography than women."

Dr Petra? Dr Petra...? Paging Dr Petra... Too bad she's on vacation, she would certainly have a field day with this news story (and the original research that spawned it):

Why men like to gaze on the female form
By Roger Highfield, Science Editor

Men find photos of the opposite sex much more "rewarding" than women, new research claims today.

According to the study men take the same pleasure out of looking at an attractive female form as they do from having a curry or making money whereas women do not take any significant reward from looking at pictures of men.

The survey published in the journal Proceedings of the Royal Society B said that brain scan studies show that "reward centres" are triggered in men when they gaze at a woman's face or body whereas they are not in females. It also shows men are more likely to make an effort to view pictures of the opposite sex and pay out money.

The findings shed light on why men are much greater consumers of pornography than women and why sales of Playboy have always exceeded those of Playgirl, according to Dr Benjamin Hayden at the Centre for Neuroeconomic Studies, Duke University School of Medicine, Durham, North Carolina.

. . .

Yes, the experiment by Hayden and colleagues (2007) actually did use images taken from the HOT or NOT site:

Two databases were generated containing over 2000 male and 2000 female images. All images were downloaded from the Hotornot web site (http://www.hotornot.com) in July 2006. This publicly accessible web site allows anyone to post a photo and receive average attractiveness ratings from the browsing public. We selected images that had only a single central subject with a clearly visible face. We eliminated photos which were blurry or small, photos with animals or displays of wealth, photos in which emotionally salient objects such as guns, snakes or motorcycles were visible, photos with subjects in provocative sexual positions or with nudity and photos in which the subjects appeared to be younger than 18 years old.

We ignored the web site's posted ratings and reassessed attractiveness in a laboratory environment. Eleven males each rated all 2000 female photographs in the female database. Eleven females each rated all 2000 male photographs in the male database. Raters were not used as test subjects in subsequent experiments. Ratings were made on a PC using a program that displayed each photo for 1s and then waited for a rating. Raters could press a button to view each photograph again. The instructions asked raters to rate each image for attractiveness on a scale from 1 to 10.

Note that none of the images were pornographic in nature, but that didn't stop Mr. Highfield from extrapolating the results to purchases of Playboy. The Daily Telegraph article also leads you to believe it's a neuroimaging study, but it's not.

Hayden BY, Parikh PC, Deaner RO, Platt ML. Economic principles motivating social attention in humans. Proc Biol Sci. 2007 May 8; [Epub ahead of print].

We know little about the processes by which we evaluate the opportunity to look at another person. We propose that behavioural economics provides a powerful approach to understanding this basic aspect of social attention. We hypothesized that the decision process culminating in attention to another person follows the same economic principles that govern choices about rewards such as food, drinks and money. Specifically, such rewards are discounted as a function of time, are tradable for other rewards, and reinforce work. Behavioural and neurobiological evidence suggests that looking at other people can also be described as rewarding, but to what extent these economic principles apply to social orienting remains unknown. Here, we show that the opportunity to view pictures of the opposite sex is discounted by delay to viewing, substitutes for money and reinforces work. The reward value of photos of the opposite sex varied with physical attractiveness and was greater in men, suggesting differential utility of acquiring visual information about the opposite sex in men and women. Together, these results demonstrate that choosing whom to look at follows a general set of economic principles, implicating shared neural mechanisms in both social and non-social decision making.

It won't be long before we see the fMRI version.



ADDENDUM: for a discussion of this paper by an economist, see purple motes.

C'mon, Aren't Faces REALLY Special?

A recently published paper in Nature Neuroscience by Thierry and colleagues (2007) claimed that faces really aren't that special after all, particularly where the N170 component is concerned. The Neurocritic covered this article (perhaps a little too UNcritically) back in March: Are Faces Special? Fellow bloggers at The Phineas Gage Fan Club and Cognitive Daily also posted about the paper. What did it claim to show? Let's review some material from a previous post.

An ever-controversial topic in the field of high-level vision and object recognition is the question of whether faces have a privileged status relative to other objects, processed by a special modular region of ventral temporal cortex called the fusiform face area (Kanwisher et al., 1997; Kanwisher & Yove, 2006; McKone et al., 2007), or whether faces are just one example of a stimulus class that requires substantial expertise in order to distinguish between similar exemplars (Gauthier et al., 1999, 2000; Gauthier & Bukach, 2007). A new article in Nature Neuroscience tackles this issue and comes up with a surprising answer.

Thierry and colleagues (2007) recorded event-related potentials (ERPs), which are synchronized brain waves time-locked to the occurrence of particular stimuli or events. In particular, the N170 component is thought to be a highly specific ERP response to faces (as opposed to other objects) that shows a peak at 170 msec after stimulus presentation (Bentin et al, 1996).

Bentin et al. (1996)

In the new NN paper, Thierry et al. argue that previous studies of the N170 component did not adequately control for variability across stimulus classes, i.e., face stimuli have been much more similar to each other than the non-face stimuli.

The bottom line was that if interstimulus perceptual variance was adequately controlled across stimulus classes, the specificity of N170 for faces went away. [But an even earlier component, P1, popped up to discriminate between faces and cars. This wasn't adequately explained.]

But wait! There are problems with this paper -- as outlined by Bruno Rossion from the Face Categorisation Lab in Belgium -- not the least of which is that Thierry et al. didn't adequately control for interstimulus variance in their own study! His reply (and perhaps others) will appear in a future issue of Nature Neuroscience. Watch his web site (and this space) for an update as it occurs. As for now, you can read Bruno's comments here.

Reference

Thierry G, Martin CD, Downing P, Pegna AJ (2007). Controlling for interstimulus perceptual variance abolishes N170 face selectivity. Nature Neuroscience 10:505-511.

Weird Psychiatric Disorder Day

This morning's brief movie capsule didn't explain either delusional parasitosis or folie à deux. Wikipedia says that

Delusional parasitosis is a form of psychosis in which sufferers hold a delusional belief they are infested with parasites.

Mind Hacks has the best description of this bizarre condition in The curious case of Morgellons disease:

Morgellons is claimed to be a new form of skin disease by its sufferers but has been largely ignored by the medical community and some have claimed it is, in reality, a psychotic syndrome akin to delusional parasitosis.

Michael Shannon's character in Bug suffered from delusions that far exceeded mere aphid infestation, and he easily persuaded his drunk, drug-using, desperate and lonely new girlfriend (Ashley Judd) that the tiny bugs were real, so that she spiraled down with him in a folie à deux:

(literally, "a madness shared by two") is a rare psychiatric syndrome in which a symptom of psychosis (particularly a paranoid or delusional belief) is transmitted from one individual to another. ... Recent psychiatric classifications refer to the syndrome as shared psychotic disorder (DSM-IV) (297.3) and induced delusional disorder (folie à deux) (F.24) in the ICD-10, although the research literature largely uses the original name.

The director was William Friedkin, of The Exorcist fame, so be prepared for some over-the-top gory scenes of self-mutilation and self-dentistry (as well as some dark humor and romantic love).


Bug (2006) - Brian F. O'Byrne, Michael Shannon

Delusional Parasitosis AND Folie a Deux!

In one movie! In a word, Bug.


Bug (2006) - Michael Shannon, Ashley Judd

Synesthetes Show Greater Connectivity in the Inferior Temporal Cortex

Ah ah

Something ain't right
I'm gonna get myself
I'm gonna get myself
I'm gonna get myself connected

--Stereo MC's, Connected

SYNESTHESIA can be defined as

...an unusual conscious experience, in which stimulation of one sensory modality leads to a sensory experience in a second, unstimulated sensory modality. For example, seeing letters might lead some people to see colors.

Previous neuroimaging studies have observed activations in V4 (a color processing region of visual cortex) when "colored hearing" synesthetes listened to spoken words (Nunn et al., 2002; Paulesu et al., 1995) and when grapheme-color synethetes viewed letters (Hubbard et al., 2005; Sperling et al., 2006). It has long been hypothesized (Ramachandran & Hubbard, 2001), but never proven, that people with synesthetic abilities have an unusual degree of connectivity between the brain regions involved in coding two (or more) sensory modalities. A brand new study by Rouw and Scholte (2007) used diffusion tensor imaging, a magnetic resonance imaging method that provides images of white matter tracts, to demonstrate just that. Although the authors found increased anisotropy in multiple areas [explained by hand-waving], indicative of greater connectivity, they emphasized the differences in inferior temporal cortex because of its role in processing color and letter/word stimuli.

Increased diffusion anisotropy reflects increased or more coherent connectivity due to microstructural aspects such as degree of myelination, axonal diameter, and density and coherence in fiber orientation as well as macrostructural features such as intravoxel fiber-tract coherence.

Figure 2. Increased brain activation and increased anisotropy in the inferior temporal cortex in grapheme-color synesthetes. The white matter skeleton (green) is projected on an MNI brain (grayscale). Greater BOLD signal (blue) as well as greater anisotropy (yellow) underlie synesthetic experiences in color-grapheme synesthesia. [from Rouw & Scholte, 2007]

Rouw R & Scholte HS (2007). Increased structural connectivity in grapheme-color synesthesia. Nature Neuroscience. Published online: 21 May 2007.

Diffusion tensor imaging allowed us to validate for the first time the hypothesis that hyperconnectivity causes the added sensations in synesthesia. Grapheme-color synesthetes (n = 18), who experience specific colors with particular letters or numbers (for example, 'R is sky blue'), showed greater anisotropic diffusion compared with matched controls. Greater anisotropic diffusion indicates more coherent white matter. Anisotropy furthermore differentiated subtypes of grapheme-color synesthesia. Greater connectivity in the inferior temporal cortex was particularly strong for synesthetes who see synesthetic color in the outside world ('projectors') as compared with synesthetes who see the color in their 'mind's eye' only ('associators'). In contrast, greater connectivity (as compared with non-synesthetes) in the superior parietal or frontal cortex did not differentiate between subtypes of synesthesia. In conclusion, we found evidence that increased structural connectivity is associated with the presence of grapheme-color synesthesia, and has a role in the subjective nature of synesthetic color experience.

Or, as this witty headline puts it, it's a...

Red-letter day for brain connectivity
More neural connections may explain synesthesia
Staff Writers 21/05/2007 11:24:24

People with grapheme-colour synesthesia - who see a cascade of colours associated with individual letters when looking at a page of text - appear to have more neural connections in areas of the brain involved in word processing and binding perceptions together, a new study shows.

References

Hubbard EM, Arman AC, Ramachandran VS, Boynton GM. (2005). Individual differences among grapheme-color synesthetes: brain-behavior correlations. Neuron 45:975-85.

Nunn JA, Gregory LJ, Brammer M, Williams SC, Parslow DM, Morgan MJ, Morris RG, Bullmore ET, Baron-Cohen S, Gray JA. (2002). Functional magnetic resonance imaging of synesthesia: activation of V4/V8 by spoken words. Nat Neurosci. 5:371-5.

Paulesu E, Harrison J, Baron-Cohen S, Watson JD, Goldstein L, Heather J, Frackowiak RS, Frith CD. (1995). The physiology of coloured hearing. A PET activation study of colour-word synaesthesia. Brain 118:661-76.

Ramachandran VS & Hubbard, EM. (2001). Psychophysical investigations into the neural basis of synaesthesia. Proc. R. Soc. Lond. B 268:979–983.

Rich AN, Williams MA, Puce A, Syngeniotis A, Howard MA, McGlone F, Mattingley JB. (2006). Neural correlates of imagined and synaesthetic colours. Neuropsychologia 44:2918-25.

If you make sure you're connected
The writing's on the wall
But if your mind's neglected
Stumble you might fall
Stumble you might fall
Stumble you might fall

--Stereo MC's, Connected

Neurobiological Correlates of Melbourne-Sydney Rivalry

You think I made this up? I can't find the article online yet, but here's the abstract.

Velakoulis D, Fornito A, Walterfang M, Malhi G, Yucel M, Pantelis C. (2007). A tale of two cities: a neuroimaging investigation of Melbourne-Sydney rivalry comparing cortical thickness in healthy adults. Australas Psychiatry 15(1):67-71.

OBJECTIVE: We sought to identify neurobiological correlates of Melbourne-Sydney rivalry through neuroimaging measures of a key brain region involved in cognitive and emotional regulation. METHOD: Twenty subjects from each city were recruited from two large neuroimaging databases, and were scanned on a GE Signa 1.5 T magnetic resonance imaging scanner. Cortical thickness of the anterior cingulate cortex (ACC) was measured using a tessellated mesh method, after image segmentation. These measures were compared with key sporting, financial and academic variables. RESULTS: Residents of Melbourne had a significantly thicker ACC (p less than 0.0001) than Sydney residents, and this difference remained significant when age and intracranial volume were controlled for (p = 0.001). This difference mirrored that in variables measuring wealth, sporting and academic success. CONCLUSIONS: The thinner ACC seen in Sydney-siders may reflect the effects of increased stress due to elevated property prices, relative lack of sporting success and other variables. An alternative explanation is that a thinner ACC is the result of increasing cortical refinement and efficiency, and a marker of a more mature city. However, if these findings are a result of latitudinal effects, this may have significant implications for residents of more northern regions of the Australian continent.

[NOTE: the authors are from the Melbourne Neuropsychiatry Centre, University of Melbourne, Melbourne, Vic, Australia.]

Perhaps the current issue of Australasian Psychiatry is similar to the (semi-)joke issue published by the British Medical Journal around Christmas...

NAcc Localization for DBS

The topographical location of the nucleus accumbens in relation to other brain structures on a horizontal plane 3 mm below the AC-PC plane (Schlaepfer et al., 2007).

As the previous post discussed, the nucleus accumbens (NAcc) is an experimental target for deep brain stimulation in severe forms of depression that have failed to respond to other treatments such as psychotherapy, antidepressants (and other drugs), and the ever-controversial electroconvulsive therapy, or ECT [see current edit wars at Wikipedia].

Position of deep brain stimulation electrodes

The location of the lowest contact of the stimulation electrode in a horizontal and coronal plane with projections of the left (green) and right (yellow) electrode path in the surgical planning stage. Stereotaxic coordinates are 1.5 mm rostral to the anterior edge of the anterior commissure, measured at the crossing point, 4 mm ventral and 7–8 mm lateral of the midline of the third ventricle. Burr holes were placed deep fronto laterally (Schlaepfer et al., 2007).

Theoretical motivations behind the procedure:

We believe that DBS to the ventral striatum, and in particular, the nucleus accumbens, will be a promising and efficacious treatment of severe depression. Our hypothesis is based on three lines of reasoning: (1) the ventral striatum is heavily implicated in both normal and abnormal reward processes, (2) the nucleus accumbens acts as a 'motivation gateway' between limbic systems involved in emotion and systems involved in motor control, and (3) the ventral striatum is uniquely located to modulate activity in other regions of the brain.

The case histories of the three patients included in the trial are predictably, well, depressing in their inability to obtain relief from any other form of treatment:

Patient 01 is a 66-year-old woman suffering from major depression since age 21. The current depression episode was her sixth, and lasted for 17 months. During the current episode, the patient failed seven antidepressant medication trials, and augmentation with five different neuroleptics also failed. The patient did not respond to both an adequate trial of psychotherapy and 13 treatments of bilateral ECT. At study entry the patient was severely depressed, with a Hamilton Depression scale (HDRS24) score of 38. At study entry she was treated with 90 mg duloxetine, 1 mg risperidone, 10 mg diazepam, 75 mg L-thyroxin, and 75 mg melperone.

Patient 02 is a 37-year-old unemployed university graduate (economics). The current episode was his second, and began 9 years ago. Seventeen different antidepressant medication treatments have failed, as did augmentation with five neuroleptics and lithium. The patient had four courses of unsuccessful ECT treatments with at least 10 treatment sessions (twice unilateral, twice bilateral), and psychotherapy was tried, again to no avail. At study entry he was treated with 50 mg quietapine and 75 mg amitryptiline.

Patient 03 is the 37-year-old monozygotic twin brother of patient 02; unipolar major depression had developed in both patients in almost exactly the same way at the same time, he had the same professional education and current state as his brother. His current episode began 11 years ago, and this patient has been unsuccessfully treated with at least eight antidepressant medications, and augmentation with at least three neuroleptics and with lithium failed. The patient had two ECT treatment courses (one unilateral and one bilateral), comprising 10 and 15 treatment sessions, respectively, with no success, and psychotherapy also failed. ... At study entry they were severely depressed (HDRS24 score of 31 and 32). At study entry he was treated with 50 mg quietapine, 150 mg amitryptiline, and 75 mg L-thyroxin.

The stimulator was turned on and off in a double-blind fashion, and...

Clinical ratings improved in all three patients when the stimulator was on, and worsened in all three patients when the stimulator was turned off. These effects were immediate and bi-directional (eg when the stimulator was turned off, depression ratings immediately worsened, and when the stimulator was turned on, depression ratings immediately improved).

The figure to the left shows that each patients' score on depression rating scales, MADRAS (Montgomery-Åsberg Depression Rating Scale) and HDRS24 (Hamilton Depression Rating Scale, 24-item version) -- shown in red and green lines, respectively -- fell when the stimulator was on (shown in purple line and indicated by gray shading).

Finally, PET imaging was performed before and after stimulation to examine which brain areas responded to the treatment. Predictably, after one week of stimulation, greater blood flow was observed in the NAcc. Metabolism also increased in dorsolateral and dorsomedial prefrontal cortex and in the amygdala [?? - which one might expect is overactive already in depression; see Drevets, 1999] but decreased in ventrolateral and ventromedial prefrontal cortex, caudate, and thalamus.

Caveats? Limitations?

These findings should be taken as very preliminary at the clinical level. We certainly do not suggest that DBS to the nucleus accumbens is a 'magic bullet' procedure that will cure depression.

References

Drevets WC. (1999). Prefrontal cortical-amygdalar metabolism in major depression. Ann NY Acad Sci. 877:614-37.

Schlaepfer TE, Cohen MX, Frick C, Kosel M, Brodesser D, Axmacher N, Joe AY, Kreft M, Lenartz D, Sturm V. Deep Brain Stimulation to Reward Circuitry Alleviates Anhedonia in Refractory Major Depression. Neuropsychopharmacology 2007 Apr 11; [Epub ahead of print]