Impaired inhibition of return during free-viewing behaviour in patients with schizophrenia

Ken-Ichi Okada,Masao Iwase,Ichiro Fujita,Kentaro Morita,Mikio Inagaki,Masatoshi Yoshida,Takashi Shinozaki,Hidenaga Yamamori,Michiko Fujimoto,Kenichiro Miura,Ryota Hashimoto,Yuka Yasuda

doi:10.1038/s41598-021-82253-w

Abstract

Schizophrenia affects various aspects of cognitive and behavioural functioning. Eye movement abnormalities are commonly observed in patients with schizophrenia (SZs). Here we examined whether such abnormalities reflect an anomaly in inhibition of return (IOR), the mechanism that inhibits orienting to previously fixated or attended locations. We analyzed spatiotemporal patterns of eye movement during free-viewing of visual images including natural scenes, geometrical patterns, and pseudorandom noise in SZs and healthy control participants (HCs). SZs made saccades to previously fixated locations more frequently than HCs. The time lapse from the preceding saccade was longer for return saccades than for forward saccades in both SZs and HCs, but the difference was smaller in SZs. SZs explored a smaller area than HCs. Generalized linear mixed-effect model analysis indicated that the frequent return saccades served to confine SZs’ visual exploration to localized regions. The higher probability of return saccades in SZs was related to cognitive decline after disease onset but not to the dose of prescribed antipsychotics. We conclude that SZs exhibited attenuated IOR under free-viewing conditions, which led to restricted scene scanning. IOR attenuation will be a useful clue for detecting impairment in attention/orienting control and accompanying cognitive decline in schizophrenia.

Highlights

Schizophrenia affects various aspects of cognitive and behavioural functioning
In the present investigation we studied the properties of exploratory saccades in SZs and compared them with those in healthy control participants (HCs)
We found that (i) SZs had impairments in inhibition of return (IOR) under free-viewing conditions, (ii) SZs explored a smaller area of the visual scene, (iii) the attenuated IOR and the resulting repeated visits to previously explored regions were a partial cause of the limited scanning, and (iv) the frequency of return saccades in SZs was related to cognitive decline but not to the dose of prescribed antipsychotics

Summary

Introduction

Schizophrenia affects various aspects of cognitive and behavioural functioning. Eye movement abnormalities are commonly observed in patients with schizophrenia (SZs). SZs’ atypical visual exploration is characterized by lower saccade frequency, smaller saccade amplitude, and longer fixation duration[6,19,20,21,22] It remains unclear whether these features alone can sufficiently explain the atypical visual exploration in SZs, or whether there is another feature reflecting the deficit in their attention/ orienting system. One such possible feature is repeated visits to previously explored regions, possibly reflecting an abnormality in inhibition of return (IOR)

Methods

Results

Conclusion