Brain compensation during visuospatial working memory in premanifest Huntington's disease

In this study, we used a quantitative model of compensation, known as the CRUNCH (Compensation-Related Utilization of Neural Circuits Hypothesis), to explicitly characterise compensation in pre-HD. The assumption of the model is that fMRI activity increases as task difficulty increases (compensatory effect). However, when individuals reach the ‘CRUNCH’ point, where task difficulty exceeds their neural resources, fMRI activity and performance declines. We acquired fMRI data (n = 15 pre-HD; n = 15 controls) during performance of an fMRI visuospatial working memory task with low, intermediate-1, intermediate-2, and high memory loads. Consistent with the CRUNCH prediction, pre-HD individuals showed decreased fMRI activity in left intraparietal sulcus at high memory load, compared to healthy controls who showed increased fMRI activity in left intraparietal sulcus at high memory load. Contrary to the other CRUNCH prediction, the pre-HD group did not show compensatory increase in fMRI activity at lower levels of memory loads in left intraparietal sulcus. Our findings provide partial support for the validity of CRUNCH in pre-HD.
Source: Neuropsychologia - Category: Neurology Source Type: research