When synesthesia and savant abilities are mistaken for hallucinations and delusions: contribution of a cognitive approach for their differential diagnosis

Anti-PDHA1 antibody is detected in a subset of patients with schizophrenia

Autoantibodies have been implicated in schizophrenia aetiology. Here, novel autoantibodies were isolated from patients with schizophrenia. Autoantibody candidates were searched using two-dimensional gel electrophoresis and western blotting with rat brain proteins as antigens and two sera pools (25 schizophrenia patients versus 25 controls) as antibodies. Immunoreactive antigens were identified by mass spectrometry. Antibody prevalence were evaluated by western blotting using human recombinant proteins. Furthermore, brain magnetic resonance imaging data (regional brain volumes and diffusion tensor imaging measures) were compared. Two proteins of the mitochondrial respiration pathway were identified as candidate antigens. Three patients with schizophrenia, but no controls, expressed antibodies targeting one of the candidate antigens, i.e., pyruvate dehydrogenase E1 component subunit alpha, somatic form, mitochondrial (PDHA1, EC 1.2.4.1), which is related to mitochondrial energy production. Anti-PDHA1 antibody-positive patients (n = 3) had increased volumes in the left occipital fusiform gyrus compared to both controls (n = 23, p = 0.017) and antibody-negative patients (n = 16, p = 0.009), as well as in the left cuneus compared to antibody-negative patients (n = 16, p = 0.018). This is the first report of an anti-PDHA1 antibody in patients with schizophrenia. Compatible with recent findings of mitochondrial dysfunction in schizophrenia, this antibody may be involved in the pathogenesis of a specific subgroup of schizophrenia.

How non-veridical perception drives actions in healthy humans: evidence from synaesthesia

We continually perform actions that are driven by our perception and it is a commonly held view that only objectively perceived changes within the 'real' world affect behaviour. Exceptions are generally only made for mental health disorders associated with delusions and hallucinations where behaviour may be triggered by the experience of objectively non-existent percepts. Here, we demonstrate, using synaesthesia as a model condition (in N = 19 grapheme-colour synaesthetes), how objectively non-existent (i.e. non-veridical) but still non-pathological perceptions affect actions in healthy humans. Using electroencephalography, we determine whether early-stage perceptual processes (reflected by P1 and N1 event-related potential (ERP) components), or late-stage-integration processes (reflected by N2 component), underlie the effects of non-veridical perceptions on action control. ERP analysis suggests that even though the examined peculiarities and experimental variations are perceptual in nature, it is not early-stage perceptual processes, but rather higher-order executive control processes linking perceptions to the appropriate motor response underlying this effect. Source localization analysis implicates activation within medial frontal cortices in the effect of how irrelevant non-veridical perceptions modulate behaviour. Our results challenge common conceptions about the determinants of human behaviour but can be explained by well-established theoretical frameworks detailing the link between perception and action. This article is part of a discussion meeting issue 'Bridging senses: novel insights from synaesthesia'.