Spatial working memory dysfunction in minimal hepatic encephalopathy: an ethology and BOLD-fMRI study.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Medical Imaging

Background:

• Minimal hepatic encephalopathy (MHE) affects individuals with no overt symptoms but with abnormal test results.
• Cognitive impairments in MHE impact daily life, necessitating treatment.
• Spatial working memory is crucial for daily functioning.

Purpose of the Study:

• To investigate the neural mechanisms underlying spatial working memory deficits in MHE patients.
• To compare brain activity during a spatial working memory task in MHE patients, cirrhosis patients without MHE, and healthy controls.

Main Methods:

• Behavioral testing using the Wechsler Memory Scale-Chinese revised (WMS-CR).
• Blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD-fMRI) during an n-back task.
• Analysis of neural activation in regions of interest including bilateral prefrontal cortex (PFC), premotor area (PreMA), supplementary motor area (SMA), and parietal areas (PA).

Main Results:

• MHE patients showed lower memory quotients, primarily affecting short-term and transient memory.
• Performance accuracy was reduced, and reaction times were prolonged in MHE patients compared to controls.
• BOLD-fMRI revealed diminished load-dependent activation in PFC and SMA, and overall lower activation intensities in ROIs for MHE patients compared to controls.

Conclusions:

• MHE patients exhibit significant spatial working memory impairment.
• Dysfunction in bilateral PFC, PreMA, SMA, and PA contributes to spatial working memory deficits in MHE.
• Prefrontal cortex impairment is a likely neural basis for spatial working memory dysfunction in MHE.