Changes in pupil diameter are correlated with the occurrence of pareidolias in patients with dementia with Lewy bodies

Suzuki, Yumi; Hirayama, Kazumi; Shimomura, Tatsuo; Uchiyama, Makoto; Fujii, Hiromi; Mori, Etsuro; Nishio, Yoshiyuki; Iizuka, Osamu; Inoue, Ryusuke; Otsuki, Mika; Sakai, Shinya

doi: 10.1097/WNR.0000000000000735
Clinical Neuroscience

Pareidolias are visual illusions of meaningful objects, such as faces and animals, that arise from ambiguous forms embedded in visual scenes. Pareidolias and visual hallucinations have been suggested to have a common underlying neural mechanism in patients with dementia with Lewy bodies (DLB). The aim of the present study was to find an externally observable physiological indicator of pareidolias. Using a pareidolia test developed by Uchiyama and colleagues, we evoked pareidolias in patients with DLB and recorded the resultant changes in the diameters of their pupil. The time frequencies of changes in pupil diameters preceding pareidolic utterances and correct utterances by the patients, as well as correct utterances by healthy control participants, were analyzed by a fast Fourier transform program. The power at time frequencies of 0–0.46 Hz was found to be greatest preceding pareidolic utterances in patients with DLB, followed by that preceding correct utterances in control participants, followed by that preceding correct utterances in patients with DLB. When the changes in power preceding the utterance were greater than the median value of correct utterances by the control group, the frequency of pareidolic utterances was significantly greater than that of correct utterances and when the changes were the same as or lower than the median value, the frequency of correct utterances was significantly greater than that of pareidolic utterances. Greater changes in power preceding the utterance at time frequencies of 0–0.46 Hz may thus be an externally observable physiological indicator of the occurrence of pareidolias.

aDivision of Health Sciences, Graduate School of Health Sciences

bDepartment of Functioning and Disability, Faculty of Health Sciences, Hokkaido University, Sapporo

cGraduate School of the Yamagata Prefectural University of Health Sciences, Yamagata

dDepartment of Rehabilitation Medicine, Akita Prefectural Centre of Rehabilitation and Psychiatric, Akita

eDepartment of Speech, Language and Hearing Sciences, Niigata University of Health and Welfare, Niigata

fDepartment of Behavioural Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai

gDepartment of Occupational Therapy, School of Rehabilitation Sciences, Health Sciences University of Hokkaido, Tobetsu, Japan

Correspondence to Shinya Sakai, PhD, Department of Functioning and Disability, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido 060-8638, Japan Tel: +81 11 70 3388; fax: +81 11 706 3388; e-mail: sakai@hs.hokudai.ac.jp

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Received November 10, 2016

Accepted December 22, 2016

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