Fig. 1
From: Evidence for causal top-down frontal contributions to predictive processes in speech perception
An illustration of the experimental motivation. a A schematic Bayesian framework for predictive coding in speech perception. b The putative brain basis of this framework28. Predictions are generated in inferior frontal gyrus and/or frontal motor speech regions (pink), and instantiated in auditory regions of superior temporal lobe (pale blue). c The two dimensional experimental manipulation employed here to detect a dissociation between normal temporal lobe responses to sensory detail (number of vocoder channels) and abnormal frontal lobe responses to prior congruency. d Our experiment relies on detecting the consequences of degraded predictions in abnormal frontal brain regions by measuring their effects in normal temporal regions. e Voxel-based morphometry in our patient group. Regions coloured in red displayed consistent reductions in grey matter volume (FWE p < 0.05). Regions coloured blue had strong evidence for normal cortical volume in nfvPPA (Bayesian probability of the null >0.7, cluster volume>1 cm3). Uncoloured (grey) areas had no strong evidence for or against atrophy
