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Larry A Abel, Andrea Phillipou, Susan Lee Rossell, David Castle, Caroline Gurvich; Saccadic control in anorexia nervosa. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3996.
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© ARVO (1962-2015); The Authors (2016-present)
Anorexia Nervosa (AN) is a psychiatric illness characterised by 3 main criteria: significantly low body weight, a fear of weight gain and a disturbance in the experience of one’s own body weight or shape. Neurobiology studies in AN have been inconsistent. Since the neurobiology of saccades is relatively well understood, we examined tasks ranging from simple prosaccades to the scanning of clinically relevant images, as has been done in other psychiatric disorders.
24 AN subjects and 25 age-matched controls (all female) were studied. Eye movements were recorded at 500 Hz. Prosaccades, antisaccades and a go/no-go task were interleaved and cued by colour of the fixation spot. Memory-guided and self-paced saccades were also studied. During fMRI scanning, subjects viewed emotional faces and were asked to identify gender, not emotion; an image of their own face was interleaved. They also viewed biological motion stimuli showing walkers of both sexes and differing weights, either identifying sex or estimating weight.
Prosaccade latency was significantly shorter for AN: 206.87±33.72 vs. 250.42±70.97ms, p=.011. Other prosaccade parameters were normal, as were the antisaccade & go/no-go tasks. AN participants made significantly more errors on the memory-guided task: 14.81±10.98 vs.8.47±5.32, p=.021. Intersaccadic interval on the self-paced task fell just short of significance: 164.46±156.12 vs. 401.67±51.28ms, p =.068. For emotional faces AN subjects made significantly more fixations than controls: 23.67±1.02 vs. 20.42±.99, p=.027. Their fixation durations were also briefer: 279.06±18.1 vs. 351.65±17.21ms, p=.006. When viewing their own faces, AN subjects attended salient and non-salient features equally; controls attended to the salient features (the inner face “triangle”) more. For biological motion, fixations were again more frequent and briefer for AN subjects than controls.
Prosaccade generation was intact but initiation was abnormally short in AN. This and the brief fixations for faces and biological motion could point to weaker fixation drive but the hyperscanning on the face and biological motion tasks is consistent with that seen in anxiety disorders. Their normal antisaccades and impaired memory-guided saccades differ from results in obsessive-compulsive disorder, with which AN shares some features. This 1st study of saccades in AN reveals a distinctive pattern of performance.
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