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

Bouvet, Lucie; Barbier, Jacques-Edouard; Cason, Nia; Bakchine, Serge; Ehrlé, Nathalie

doi:10.1080/13854046.2017.1288269

Cited by 7 publications

(8 citation statements)

References 39 publications

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“…by experiences in which a perceptual presence or real-world perceptual veridicality is lacking. By examining synaesthesia, a perceptual phenomenon in healthy humans distinct from psychopathological delusions or hallucinations [10], we show behavioural effects and identify plausible neuronal correlates of how this is possible. Graphemecolour synaesthesia is a condition in which single digits, letters and words (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…is non-veridical) [9]. Thereby, synaesthesia can clearly be differentiated from hallucinations and delusions associated with psychopathology or drug-induced states, and can serve as a useful tool for studying the underlying neurophysiology of healthy non-veridical perceptions relevant to the higher-order cognitive control of action [10,11]. Using synaesthesia as a model condition, we show how non-pathological perceptual feature dimensions that are not objectively perceived as present in the real world (i.e.…”

Section: Introductionmentioning

confidence: 99%

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

Schreiter

Chmielewski

Ward

et al. 2019

Phil. Trans. R. Soc. B

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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’.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Schreiter

Chmielewski

Ward

et al. 2019

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

show abstract

“…by experiences in which a perceptual presence or real-world perceptual veridicality is lacking. By examining synaesthesia, a perceptual phenomenon in healthy humans distinct from psychopathological delusions or hallucinations (Bouvet et al, 2017), we detail the mechanisms how this is possible. Grapheme-colour synaesthesia is a condition in which single digits, letters and words (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…is nonveridical or illusory) (Seth, 2014). Thereby, synaesthesia can clearly be differentiated from hallucinations and delusions associated with psychopathology, and can serve as a useful tool for studying the underlying neurophysiology of healthy non-veridical perceptions relevant to the higher-order cognitive control of action (Sagiv and Frith 2013;Bouvet et al 2017). Using synaesthesia as a model condition, we show how non-pathological perceptual feature dimensions that are not objectively perceived as present in the real world (i.e.…”

Section: Introductionmentioning

confidence: 98%

How non-veridical perception drives actions in healthy humans - Evidence from Synaesthesia

Schreiter

Chmielewski

Ward

et al. 2018

Preprint

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We continually perform actions driven by our perception and it is commonly held that only objectively perceived changes within the 'real' world affect behaviour. Exceptions are usually only made for clinical conditions associated with hallucinations, where objectively non-existent percepts can influence behavior. Using synaesthesia as a model condition, we show that even in healthy populations irrelevant non-veridical precepts exert an effect on action. By non-veridical we refer to stimulus dimensions that are only subjectively perceived to be there. Applying electrophysiological (EEG) methods, we show that although these examined peculiarities are perceptual in nature, not primarily perceptual processes underlie the effects of irrelevant nonveridical perceptions on actions. Rather, high-order processes linking perceptions and motor control in medial frontal cortices reflect the underlying mechanism how irrelevant non-veridical perceptions modulate behaviour. Our results challenge assumptions about the determinants of healthy human behaviour but can be embedded within existing frameworks detailing perception action interactions.

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“…Nakagami et al (2020) found that patients with anti-PDHA1 antibodies had increased volumes of the left occipital fusiform gyrus and left cuneus, a finding that is in contrast to the decreased volumes typically seen in SSD patients in comparison to controls (Nakagami et al, 2020). Increased volumes of fusiform gyrus have been previously associated with synesthesia -a disorder characterized by abnormal perception in response to the presence or absence of an external sensory stimulus -which can potentially be linked to an underlying common mechanism for hallucinations and delusions typical of SSD (Bouvet et al, 2017;Hupé et al, 2015;Weiss et al, 2009). PDHA1 dysfunction has been associated with mitochondrial dysfunction, as well as numerous neuropsychiatric disorders, including Parkinson's disease, dementia, psychosis and SSD (Nakagami et al, 2020).…”

Section: Prevalence Of Treatable Genetic Disorder Variants Within the Study Cohortmentioning

confidence: 99%

When rare meets common: Treatable genetic diseases are enriched in the general psychiatric population

Sriretnakumar

Harripaul

Kennedy

et al. 2021

Preprint

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Mental illnesses are one of the biggest contributors to the global disease burden. Despite the increased recognition, diagnosis and ongoing research of mental health disorders, the etiology and underlying molecular mechanisms of these disorders are yet to be fully elucidated. Moreover, despite many treatment options available, a large subset of the psychiatric patient population is non-responsive to standard medications and therapies. There has not been a comprehensive study to date examining the burden and impact of treatable genetic disorders (TGDs) that can present with neuropsychiatric features in psychiatric patient populations. In this study, we test the hypothesis that TGDs that present with psychiatric symptoms are more prevalent within psychiatric patient populations compared to the general population by performing targeted next-generation sequencing (NGS) of 129 genes associated with 108 TGDs in a cohort of 2301 psychiatric patients. In total, 72 putative affected and 293 putative carriers for TGDs were identified, with known or likely pathogenic variants in 78 genes. Despite screening for only 108 genetic disorders, this study showed an approximately four-fold (4.13%) enrichment for genetic disorders within the psychiatric population relative to the estimated 1% cumulative prevalence of all single gene disorders globally. This strongly suggests that the prevalence of these, and most likely all, genetic diseases are greatly underestimated in psychiatric populations. Increasing awareness and ensuring accurate diagnosis of TGDs will open new avenues to targeted treatment for a subset of psychiatric patients.

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

Abstract: In complex cases, neuropsychological and formal evaluations are necessary to establish a differential diagnosis. Moreover, the case highlights the link between synesthesia and savant abilities.

Cited by 7 publications

References 39 publications

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

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

How non-veridical perception drives actions in healthy humans - Evidence from Synaesthesia

When rare meets common: Treatable genetic diseases are enriched in the general psychiatric population

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