Impaired conscious access and abnormal attentional amplification in schizophrenia

• Published in: NeuroImage clinical Vol. 18; pp. 835 - 848
• Main Authors: Berkovitch, L., Del Cul, A., Maheu, M., Dehaene, S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.01.2018; Elsevier
• Subjects: Adult; Attention; Attention - physiology; Bottom-up; Brain - physiopathology; Cognitive Sciences; Consciousness - physiology; Electroencephalography - methods; Evoked Potentials - physiology; Female; Human health and pathology; Humans; Life Sciences; Male; Masking; Middle Aged; Neurons and Cognition; Perception - physiology; Psychiatrics and mental health; Psychosis; Reaction Time; Regular; Schizophrenia - physiopathology; Top-down; Visual awareness; Psychosis; Visual awareness; Masking; Top-down; Attention; Bottom-up
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2018.03.010

Previous research suggests that the conscious perception of a masked stimulus is impaired in schizophrenia, while unconscious bottom-up processing of the same stimulus, as assessed by subliminal priming, can be preserved. Here, we test this postulated dissociation between intact bottom-up and impaired top-down processing and evaluate its brain mechanisms using high-density recordings of event-related potentials. Sixteen patients with schizophrenia and sixteen controls were exposed to peripheral digits with various degrees of visibility, under conditions of either focused attention or distraction by another task. In the distraction condition, the brain activity evoked by masked digits was drastically reduced in both groups, but early bottom-up visual activation could still be detected and did not differ between patients and controls. By contrast, under focused top-down attention, a major impairment was observed: in patients, contrary to controls, the late non-linear ignition associated with the P3 component was reduced. Interestingly, the patients showed an essentially normal attentional amplification of the P1 and N2 components. These results suggest that some but not all top-down attentional amplification processes are impaired in schizophrenia, while bottom-up processing seems to be preserved. •An elevated consciousness threshold is observed in schizophrenia.•Under unattended conditions, brain activity was similarly reduced in schizophrenic patients and controls.•Under attended conditions, the late ignition associated with the P3 component is impaired in patients.•In schizophrenia, top-down attentional amplification is abnormal while bottom-up processing is essentially spared.