The Predictive Coding Account of Schizophrenia
Dysfunctional Interaction across Linguistic Levels?
Schizophrenia is characterized by marked language dysfunctions occurring at multiple levels of the linguistic hierarchy, ranging from lower-level auditory perception to higher-level semantic processing. To date, the neuropathology of language deficits in schizophreniaremains unresolved. Here, we aim at providing a unitary electrophysiological account of these linguistic deficits within the framework of predictive coding, which explains language dysfunctions in schizophrenia as an imbalance between prediction and incoming sensory inputs. Specifically, stepping from extant clinical neuroscience studies that investigate language dysfunctions within encapsulated linguistic levels, for the first time, we hypothesize that patients are impaired in the interaction between prediction from higher abstract linguistic levels and prediction error from lower auditory sensory levels, and that the study of these impairments may provide a phenomenological explanation of the functional deficit underlying auditory hallucinations. To this end, we will employ electroencephalography (EEG) to compare online speech perception and language processing between three groups of participants: patients with schizophrenia with and without auditory hallucinations, and matched healthy controls.