Friday, April 09, 2010

Brain correlates of anticipation and body dysmorphic disorder

For readers who like this sort of stuff, this post is a grab-bag pointing to three recent studies correlating brain activity with behavior, two on anticipation and one on body dysmorphic disorder:

A group at University College London finds that the temporal probability of expected visual events is encoded not by a single area but by a wide network that importantly includes neuronal populations at the very earliest cortical stages of visual processing. Activity in those areas changes dynamically in a manner that closely accords with temporal expectations. (These early stages have generally been thought to be locked to the visual stimulus in an invariant and automatic way. Now they appear to link with higher parietal and motor-related areas known to be involved in anticipation.)

Kahnt et al. show that reward value of sensory cues can be decoded from distributed fMRI patterns in the orbitofrontal cortex, and that value representations in the orbitofronal cortex are independent of whether reward is anticipated or actually received.

Finally, a study from UCLA in the Archives of General Psychiatry finds that subjects with body dysmorphic disorder (i.e., preoccupied with perceived defects in their appearance) show (compared with control subjects) hyperactivity in the left orbitofrontal cortex and bilateral head of the caudate when viewing their own face versus a familiar face. This suggests abnormalities in visual processing and frontostriatal systems in body dysmorphic disorder. The two most effective theraputic approaches to the disorder are cognitive behavioral therapy and treatment with serotonin-enhancing drugs, either alone or in combination. As Brody notes, what does not work is plastic surgery and other cosmetic treatments. Even if the treatments modify one presumed defect, the person is likely to come up with another, and another, and another, leading to a vicious cycle of costly and often deforming as well as ineffective remedies.

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