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Visual information processing during controlled hypoglycaemia in humans
R J McCrimmon1, I J Deary, B J Huntly
1Royal Infirmary of Edinburgh National Health Service Trust, UK.
Abstract:
A general impairment of cognitive performance occurs during acute insulin-induced hypoglycaemia, but little objective evidence is available for disruption of more specific cognitive processes. The effect of controlled hypoglycaemia on the early stages of visual information processing and contrast sensitivity was examined in a homogeneous group of 20 nondiabetic human subjects. Hypoglycaemia caused a significant disruption in general cognitive performance as assessed by a digit symbol task (P < 0.001) and the trail making B task (P < 0.05). Hypoglycaemia also produced a highly significant deterioration in performance on all of the visual information processing tasks, namely inspection time (IT) (P = 0.01), visual change detection (VCD) (P < 0.005) and visual movement detection (VMD) (P < 0.005). A significant deterioration in contrast sensitivity was observed during hypoglycaemia (P < 0.005). In contrast, no significant effect of hypoglycaemia was demonstrated on standard clinical measures of visual acuity or stereoscopic vision. Thus, although hypoglycaemia caused no detectable deterioration in visual acuity as measured by Snellen-type tests, a marked deterioration occurred in the speed of visual information processing and in contrast sensitivity. As many decisions are made under conditions of limited perceptual time and low visual contrast (e.g. when driving), the disruptive effect of moderate insulin-induced hypoglycaemia on visual perception will have important practical implications in diabetic humans exposed to this metabolic stress. The present results are congruent with other evidence which shows that the early stages of visual information processing are susceptible to deterioration by general cerebral insults.
Insights
Insulin-induced hypoglycemia significantly impairs cognitive performance, specifically slowing visual information processing and reducing contrast sensitivity. This affects tasks requiring quick visual perception, like driving.
Area of Science:
- Neuroscience
- Ophthalmology
- Endocrinology
Background:
- Acute insulin-induced hypoglycemia is known to impair general cognitive function.
- Limited objective evidence exists regarding its specific effects on detailed cognitive processes, particularly visual perception.
Purpose of the Study:
- To investigate the impact of controlled hypoglycemia on early visual information processing and contrast sensitivity in non-diabetic subjects.
- To determine if visual acuity is affected, contrasting with more sensitive visual processing measures.
Main Methods:
- Twenty healthy, non-diabetic subjects participated in the study.
- Controlled insulin-induced hypoglycemia was administered.
- Cognitive performance was assessed using digit symbol and trail making B tasks.
- Visual information processing was evaluated through inspection time (IT), visual change detection (VCD), and visual movement detection (VMD) tasks.
- Contrast sensitivity and visual acuity were measured.
Main Results:
- Hypoglycemia significantly disrupted general cognitive performance (digit symbol, trail making B).
- A marked deterioration was observed in visual information processing speed (IT, VCD, VMD).
- Contrast sensitivity significantly decreased during hypoglycemia.
- Standard visual acuity and stereoscopic vision remained unaffected.
Conclusions:
- Moderate insulin-induced hypoglycemia significantly impairs early visual information processing and contrast sensitivity, despite not affecting visual acuity.
- These findings highlight practical implications for activities requiring rapid visual perception under conditions of low contrast or limited time, such as driving.
- The results support the notion that early visual processing stages are vulnerable to cerebral insults like hypoglycemia.