F4 Neurophysiological and behavioural evidence of posterior-cortical alterations associated to specific deficits on face-pareidolia recognition in premanifest huntington's disease. (13th September 2016) - Martinez-Horta, Saul
Abstract : Background: In Huntington's disease (HD) posterior-cortical changes can be seen up to 15 years prior diagnosis. However, functional implications of these changes are partially understood. Posterior-cortical brain territories involved in facial recognition are sensible to HD progression. Its functional integrity can be assessed measuring the early neuroelectric responses elicited by facial stimulus -known as the N170 component- over occipito-temporal locations. Objectives: To explore potential changes on the N170 morphology and related behavioural/clinical measures in premanifest HD (preHD). Methods: 16 preHD (CAG > 39) and 16 controls matched for age, sex and education were enrolled. Clinical and socio-demographic variables were recorded emphasising on measures sensible to HD progression (apathy, UHDRS-TMS, DBS and cognition). EEG was recorded during a simple discrimination task based on objects, faces and face-pareidolia recognition. Results: No behavioural/neurophysiological differences were found between groups for faces and objects recognition. PreHD exhibited a significantly increased number of errors on face-pareidolia recognition (p < 0.01) and a mainly inexistent N170 component in response of these stimulus (p < 0.001). This N170 reduction was significantly related to recognition errors (r = 0.548; p = 0.002), apathy (r = 0.450; p = 0.01) and cognition (r = 0.530; p = 0.003). Conclusion: Up to 15 years before diagnosis, preHD exhibit posterior-cortical functional abnormalities that disrupt the mechanisms linked to face-pareidolia processing and recognition. Specifically, our data suggests some degree of changes along the occipital-temporal extrastriate visual cortex. The evaluation of these systems appears as a sensible measure to capture early changes associated with HD progression.