Schizophrenia is a heterogeneous disease strongly influenced by genetic disposition. A large variety of candidate genes has been identified. However, each gene only explains a small proportion of the genetic risk. For this reason, stable markers, so called endophenotypes, are of primary interest.
In the last decade, we have developed an endophenotype based on visual masking, which is called the shine-through effect and we have extensively studied its characteristics. This test has a much higher sensitivity and specificity to “detect” schizophrenia than most other perceptual and cognitive paradigms (Key Publications: Herzog, Kopmann et al., 2004; Chkonia et al., 2010). Most importantly, not only schizophrenic patients show strong performance deficits but also their unaffected relatives and even unaffected people scoring high in cognitive disorganization (Cappe et al., 2012; Favrod et al., 2017) and 22q11 patients (Tomescu et al., 2015). This is crucial for an endophenotype because endopheotypes are aimed to reveal the genetic risk to suffer from disease. Our genetic analysis pointed to abnormalities in the cholinergic system, which correlated well with deficits in our visual masking paradigm (Bakanidze et al., 2013).
Based on these findings, we have developed a model that relates visual deficits to abnormally weak enhancement of target processing. We propose that vision is largely intact in the patients under normal instances. However, when stimuli are of low contrast or only briefly presented, they usually go unnoticed in both controls and patients. Only when these stimuli become behaviorally relevant and need to be enhanced, the enhancement deficits of the patients, which we relate to abnormalities in the cholinergic system, become obvious (Key Publication: Herzog et al., 2013). We propose that similar enhancement deficits can explain other symptoms of the patients, such as thought disorder, which can be viewed as an abnormality of staying focused. In line with this hypothesis, we also found that healthy students scoring high in cognitive disorganization show masking deficits, but to a much lesser degree than patients. In addition, we found that both patients and high scoring students show diminished EEG responses, which again supports the enhancement deficit hypothesis (Key Publication: Plomp et al., 2013). Depressive patients do not show masking deficits but EEG abnormalities (Favrod et al., 2019).
It is important to publish not only significant results, i.e., where patients are abnormal to controls, but also null results, i.e., where patients are not impaired, to avoid the impression that all aspects of all domains are abnormal in the patients. For example, non-retinotopic illusion processing and body ownership are intact (Lauffs et al., 2016; Grzeczkowski et al., 2018; Shaqiri et al., 2018).
- Herzog MH, Brand A (2015). Visual masking & schizophrenia. Schizophrenia Research: Cognition, 2(2), p64-71.
- Herzog MH, Roinishvili M, Chkonia E, Brand A (2013). Schizophrenia and visual backward masking: a general deficit of target enhancement. Frontiers in Psychology, 4.
- Holzer L, Urben S, Passini CM, Jaugey L, Herzog MH, Halfon O, Pihet S (2013). A Randomized Controlled Trial of the Effectiveness of Computer-Assisted Cognitive Remediation (CACR) in Adolescents with Psychosis or at High Risk of Psychosis. Behavioural and Cognitive Psychotherapy, [epub ahead of print], p1-14.
- Chkonia E, Roinishvili M, Reichard L, Wurch W, Puhlmann H, Grimsen C, Herzog MH, Brand A (2012). Patients with functional psychoses show similar visual backward masking deficits. Psychiatry Research, 198(2), p235-240.
- Chkonia E, Roinishvili M, Makhatadze N, Tsverava L, Stroux A, Neumann K, Herzog MH, Brand A (2010). The shine-through masking paradigm is a potential endophenotype of schizophrenia. PLoS ONE, 5(12), e14268.
- Chkonia E, Roinishvili M, Herzog MH, Brand A (2010). First-order relatives of schizophrenic patients are not impaired in the Continuous Performance Test. Journal of Clinical and Experimental Neuropsychology, 32(5), p481-486.
- Holzer L, Jaugey L, Chinet L, Herzog MH (2009). Deteriorated visual backward masking in the shine-through effect in adolescents with psychosis. Journal of Clinical and Experimental Neuropsychology, 31(6), p641-7.
- Bakanidze G, Roinishvili M, Chkonia E, Kitzrow W, Richter S, Neumann K, Herzog MH, Brand A, Puls I (2013). Association of the Nicotinic Receptor α7 Subunit Gene (CHRNA7) with Schizophrenia and Visual Backward Masking. Frontiers in Psychiatry, 4:133, p1-10.
- Favrod O, da Cruz JR, Roinishvili M, Berdzenishvili E, Brand A, Figueiredo P, Herzog MH, Chkonia E (2019). Electrophysiological correlates of visual backward masking in patients with major depressive disorder. Psychiatry Research: Neuroimaging, 294:111004, p1-8.
- Plomp G, Roinishvili M, Chkonia E, Kapanadze G, Kereselidze M, Brand A, Herzog MH (2013). Electrophysiological Evidence for Ventral Stream Deficits in Schizophrenia Patients. Schizophrenia Bulletin, 39(3), p547-554.
- Favrod O, Sierro G, Roinishvili M, Chkonia E, Mohr C, Herzog MH, Cappe C (2017). Electrophysiological correlates of visual backward masking in high schizotypic personality traits participants. Psychiatry Research, 254, p251-257.
- Tomescu MI, Rihs TA, Roinishvili M, Karahanoglu FI, Schneider M, Menghetti S, Van De Ville D, Brand A, Chkonia E, Eliez S, Herzog MH, Michel CM, Cappe C (2015). Schizophrenia patients and 22q11.2 deletion syndrome adolescents at risk express the same deviant patterns of resting state EEG microstates: A candidate endophenotype of schizophrenia. Schizophrenia Research: Cognition, 2(3), p159-165.
- Cappe C, Herzog MH, Herzig DA, Brand A, Mohr C (2012). Cognitive disorganisation in schizotypy is associated with deterioration in visual backward masking. Psychiatry Research, 200, p652-659.
- Roinishvili M, Cappe C, Shaqiri A, Brand A, Rürup L, Chkonia E, Herzog MM (2015). Crowding, grouping, and gain control in schizophrenia. Psychiatry Research, 226 2-3, p441-445.
- Shaqiri A, Willemin J, Sierro G, Roinishvili M, Iannantuoni L, Rürup L, Chkonia E, Herzog MH, Mohr C (2015). Does chronic nicotine consumption influence visual backward masking in schizophrenia and schizotypy?Schizophrenia Research: Cognition, 2, p93-99.
- Kunchulia M, Pilz KS, Herzog MH (2014). Small effects of smoking on visual spatiotemporal processing. Scientific Reports, 4, p7316. [⇒ pdf]
- Herzog MH, Brand A (2009). Pitting temporal against spatial integration in schizophrenic patients. Psychiatry Research, 168(1), p1-10.
- Schütze C, Bongard I, Marbach S, Brand A, Herzog MH (2007). Collinear contextual suppression in schizophrenic patients.Psychiatry Research, 150(3), p237-43.
- Brand A, Kopmann S, Marbach S, Heinze M, Herzog MH (2005). Intact and deficient feature fusion in schizophrenia. European Archives of Psychiatry and Clinical Neuroscience, 255(6), p413-8.
- Brand A, Kopmann S, Herzog MH (2004). Intact feature fusion in schizophrenic patients. European Archives of Psychiatry and Clinical Neuroscience, 254(5), p281-8.
- Herzog MH, Kopmann S, Brand A (2004). Intact figure-ground segmentation in schizophrenia. Psychiatry Research, 129(1), p55-63.
- Grzeczkowski L, Roinishvili M, Chkonia E, Brand A, Mast FW, Herzog MH, Shaqiri A (2018). Is the perception of illusions abnormal in schizophrenia? Psychiatry Research, 270, p929-939.
- Shaqiri A, Roinishvili M, Kaliuzhna M, Favrod O, Chkonia E, Herzog MH, Blanke O, Salomon R (2018). Rethinking Body Ownership in Schizophrenia: Experimental and Meta-analytical Approaches Show no Evidence for Deficits. Schizophrenia Bulletin, 44(3), 643–652.
- Lauffs MM, Shaqiri A, Brand A, Roinishvili M, Chkonia E, Öğmen H, Herzog MH (2016). Local versus global and retinotopic versus non-retinotopic motion processing in schizophrenia patients.Psychiatry Research, 246, p461-465.