Hyperexcitability and Sensory Flooding
A sizable literature characterizes hyperexcitability in people
with SSD amid subjective reports of sensory flooding (McGhie &
Chapman, 1961). Sensory flooding refers to hyper-awareness of ambient
sounds, impaired selective attention, enhanced visual illusions (e.g.,
heightened colors), and detecting meaning within meaningless stimuli
(Bunney et al., 1999; McGhie & Chapman, 1961; Micoulaud-Franchi et al.,
2012). One of the potential causes of sensory flooding is
abnormal sensory gating - differential modulation of neural responses to
relevant or irrelevant stimuli. Deficits in inhibitory sensory
gating manifest as sensory flooding (Freedman et al., 2020; Hetrick et
al., 2012; Patterson et al., 2008; Potter et al., 2006). Sensory gating
impairments in schizophrenia are observed in abnormal P50 gating
responses (Atagun et al., 2020; Javitt & Freedman, 2015; Patterson et
al., 2008), occur across SSD (e.g., schizotypal individuals with
genetic predisposition for schizophrenia, newborns of schizophrenic
parents and ultra-high risk adolescents), and increase with disease
progression (Brockhaus-Dumke et al., 2008; Luo et al., 2019). However,
the sensory gating deficits observed in schizotypal personality disorder
(Cadenhead et al., 2000; Hazlett et al., 2015; Javitt & Freedman,
2015 ) and high schizotypy (Croft et al., 2001; Park et al., 2015; Wang
et al., 2004) are smaller in magnitude compared to the deficits observed
in schizophrenia. Abnormal sensory processing, consistent withhyperexcitability is evident across the schizophrenia spectrum.