Impaired Top-Down Modulation of Saccadic Latencies in Patients with Schizophrenia but Not in First-Degree Relatives

Abstract

Impaired eye movements have a long history in schizophrenia research and meet the criteria of a reliable biomarker. However, the effects of cognitive load and task difficulty on saccadic latencies (SL) are less understood. Recent studies showed that SL are strongly task dependent: SL are decreased in tasks with higher cognitive demand, and increased in tasks with lower cognitive demand. The present study investigates SL modulation in patients with schizophrenia and their first-degree relatives. A group of 13 patients suffering from ICD-10 schizophrenia, 10 first-degree relatives, and 24 control subjects performed two different types of visual tasks: a color task and a Landolt ring orientation task. We used video-based oculography to measure SL. We found that patients exhibited a similar unspecific SL pattern in the two different tasks, whereas controls and relatives exhibited 20–26% shorter average latencies in the orientation task (higher cognitive demand) compared to the color task (lower cognitive demand). Also, classification performance using support vector machines suggests that relatives should be assigned to the healthy controls and not to the patient group. Therefore, visual processing of different content does not modulate SL in patients with schizophrenia, but modulates SL in the relatives and healthy controls. The results reflect a specific oculomotor attentional dysfunction in patients with schizophrenia that is a potential state marker, possibly caused by impaired top-down disinhibition of the superior colliculus by frontal/prefrontal areas such as the frontal eye fields.

Recent updates of eye movement abnormalities in patients with schizophrenia: A scoping review

“…For example, fixation duration gives insights regarding the looking time at an object, representing the relative engagement and the time dedicated to processing binding features that belong to an object (information). Fixation duration has been used to gain insights into cognitive control capacity; for example, what we remember, 123, 124 how we perform mental computations, 125 read, 126 solve problems, 89, 127–133 compare specific stimuli and make decisions based on integrated pieces of information 134 . Eye‐tracking technology also provides knowledge about regions of interest, and therefore answers essential questions of when and how information is being captured and processed during vision‐oriented tests 92, 135–140 .…”