Disruption of Conscious Access in Psychosis Is Associated with Altered Structural Brain Connectivity

Abstract

According to global neuronal workspace (GNW) theory, conscious access relies on long-distance cerebral connectivity to allow a global neuronal ignition coding for conscious content. In patients with schizophrenia and bipolar disorder, both alterations in cerebral connectivity and an increased threshold for conscious perception have been reported. The implications of abnormal structural connectivity for disrupted conscious access and the relationship between these two deficits and psychopathology remain unclear. The aim of this study was to determine the extent to which structural connectivity is correlated with consciousness threshold, particularly in psychosis. We used a visual masking paradigm to measure consciousness threshold, and diffusion MRI tractography to assess structural connectivity in 97 humans of either sex with varying degrees of psychosis: healthy control subjects (n = 46), schizophrenia patients (n = 25), and bipolar disorder patients with (n = 17) and without (n = 9) a history of psychosis. Patients with psychosis (schizophrenia and bipolar disorder with psychotic features) had an elevated masking threshold compared with control subjects and bipolar disorder patients without psychotic features. Masking threshold correlated negatively with the mean general fractional anisotropy of white matter tracts exclusively within the GNW network (inferior frontaloccipital fasciculus, cingulum, and corpus callosum). Mediation analysis demonstrated that alterations in longdistance connectivity were associated with an increased masking threshold, which in turn was linked to psychotic symptoms. Our findings support the hypothesis that long-distance structural connectivity within the GNW plays a crucial role in conscious access, and that conscious access may mediate the association between impaired structural connectivity and psychosis.

Mathematical Model Insights into EEG Origin under Transcranial Direct Current Stimulation (tDCS) in the Context of Psychosis

“…For instance, brain networks in mental disorders exhibit diminished FC between brain areas and, thus, a network fragmentation [ 89 ]. Enhanced functional dysconnectivity has been found in early psychosis [ 90 ] and reduced conscious access in psychosis is related to diminished long-range structural connectivity [ 91 ], thus supporting the dysconnection hypothesis in schizophrenia [ 20 , 21 ]. This fragmentation can be reversed by psychotherapy in combination with a placebo or anti-psychotics [ 92 ] and by a-tDCS [ 75 ].…”

Entangled radicals may explain lithium effects on hyperactivity

“…In particular, superoxide radicals can give rise to singlet oxygen, which can emit photons 99 . These photons could serve as quantum messengers to establish long-distance connections 100 that might be essential for consciousness 101 .…”

Entangled radicals may explain lithium effects on hyperactivity

“…In particular, superoxide radicals can give rise to singlet oxygen, which can emit photons 90 . These photons could serve as quantum messengers to establish long-distance connections 91 that might be essential for consciousness 92 .…”