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Poster Session B: Wednesday, August 13, 1:00 – 4:00 pm, de Brug & E‑Hall

Apathy as a Loss of Prior Precision in the Bayesian Brain

Rebecca S Williams¹, Michelle Naessens, Juliette Lanskey, Amirhossein Jafarian, Laura Hughes, James B Rowe; ¹University of Cambridge

Presenter: Rebecca S Williams

Apathy is defined as a reduction in goal-directed behaviour. It is pervasive in dementia and is associated with poor prognosis. Treatments remain elusive. We propose and test a new model of apathy based on Bayesian brain principles. We propose that apathy arises from a reduction in precision of beliefs regarding action outcomes. Here, we test a potential mechanism for prior precision, in the GABAergic gain of superficial pyramidal neurons in the prefrontal cortex. Fifty healthy adults (aged 50-85) undertook a goal-directed task during magnetoencephalography (MEG, Hezemans et al, 2020). Apathy was assessed using the Apathy-Motivation Index (AMI). Generative modelling was implemented to assess the involvement of three nodes in the prefrontal (PFC), premotor (PMC) and primary motor cortex (M1). See preregistration: https://tinyurl.com/wbt6rpx9. There was strong evidence confirming the negative correlation between prior precision and apathy (B=12.2, p<0.01). There was very strong evidence that lower prior precision was associated with reduced gain on the superficial pyramidal neurons in the PFC and PMC, but not M1. These results support the proposed mechanism of apathy, in terms of cognitive process (prior precision) and neural underpinning (frontal cortical gain). This opens novel avenues for the treatment of apathy.

Topic Area: Predictive Processing & Cognitive Control

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