Journal: Brain
Article Title: Decision cost hypersensitivity underlies Huntington’s disease apathy
doi: 10.1093/brain/awae296
Figure Lengend Snippet: The Apple Gathering Task in Huntington’s disease . ( A ) The Apple Gathering Task. Levels of physical effort (squeezing a handheld dynamometer) and reward (apples, worth money) are varied; here we show 25 combinations of effort and reward, for each of which participants must decide if the reward is worth the effort. Participants in the UK performed a six-by-six version of this task, not shown. ( B ) Overall, apathetic participants with Huntington’s disease (HD) accepted fewer offers than their non-apathetic counterparts and control participants. ( C ) Proportion of offers accepted varied as a function of the effort and ( D ) reward on offer. ( E ) Model parameter estimates capturing overall tendency to accept (intercept), and effects of changing reward and effort levels. Apathetic people showed greater change in behaviour as effort, but not reward, varied, compared to non-apathetic people. ( F ) Difference in acceptance between people with and without apathy was in the high effort space. ( G ) All participants reached target effort levels when exerting effort, and ( H ) choice behaviour did not differ significantly across task blocks. ( I ) Decision times did not differ by apathy status in HD. Controls had shorter decision times than people with HD. New Zealand (NZ) data only are shown in G and H for graphical purposes. Error bars show standard error of the mean. MVC = maximum voluntary contraction. * P < 0.05; ** P < 0.01; *** P < 0.001.
Article Snippet: ‘Effort’ was exerted via squeezing an individually calibrated hand dynamometer (Vernier, HD-BTA and SS25LA, Biopac Systems).
Techniques: Control