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Schizophrenia as failure of left hemispheric dominance for the phonological component of language.

Angrilli A, Spironelli C, Elbert T, Crow TJ, Marano G, Stegagno L - PLoS ONE (2009)

Bottom Line: The effect involved anterior (fronto-temporal) brain regions and was specific for the Phonological task; group differences were small or absent when subjects processed the same stimulus material in a Semantic task or during Word Recognition, i.e. during tasks that typically activate more widespread areas in both hemispheres.This loss of hemispheric dominance would explain typical symptoms, e.g. when an individual's own thoughts are perceived as an external intruding voice.The change can be interpreted as a consequence of "hemispheric indecision", a failure to segregate phonological engrams in one hemisphere.

View Article: PubMed Central - PubMed

Affiliation: Department of General Psychology, University of Padova, Padova, Italy. alessandro.angrilli@unipd.it

ABSTRACT

Background: T. J. Crow suggested that the genetic variance associated with the evolution in Homo sapiens of hemispheric dominance for language carries with it the hazard of the symptoms of schizophrenia. Individuals lacking the typical left hemisphere advantage for language, in particular for phonological components, would be at increased risk of the typical symptoms such as auditory hallucinations and delusions.

Methodology/principal findings: Twelve schizophrenic patients treated with low levels of neuroleptics and twelve matched healthy controls participated in an event-related potential experiment. Subjects matched word-pairs in three tasks: rhyming/phonological, semantic judgment and word recognition. Slow evoked potentials were recorded from 26 scalp electrodes, and a laterality index was computed for anterior and posterior regions during the inter stimulus interval. During phonological processing individuals with schizophrenia failed to achieve the left hemispheric dominance consistently observed in healthy controls. The effect involved anterior (fronto-temporal) brain regions and was specific for the Phonological task; group differences were small or absent when subjects processed the same stimulus material in a Semantic task or during Word Recognition, i.e. during tasks that typically activate more widespread areas in both hemispheres.

Conclusions/significance: We show for the first time how the deficit of lateralization in the schizophrenic brain is specific for the phonological component of language. This loss of hemispheric dominance would explain typical symptoms, e.g. when an individual's own thoughts are perceived as an external intruding voice. The change can be interpreted as a consequence of "hemispheric indecision", a failure to segregate phonological engrams in one hemisphere.

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Related in: MedlinePlus

Spline maps of scalp electrical activity (3/4 left frontal view evidencing areas involved in phonological elaboration) measured in the first second of the inter stimulus interval (iCNV), for the three linguistic tasks.Patients in the upper panel, controls in the lower panel. Negativity, in blue, indicates activation of cortical layers in this language-related CNV paradigm, positivity, in red, indicates relative inhibition.
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pone-0004507-g003: Spline maps of scalp electrical activity (3/4 left frontal view evidencing areas involved in phonological elaboration) measured in the first second of the inter stimulus interval (iCNV), for the three linguistic tasks.Patients in the upper panel, controls in the lower panel. Negativity, in blue, indicates activation of cortical layers in this language-related CNV paradigm, positivity, in red, indicates relative inhibition.

Mentions: Spline maps of scalp electrical activity measured in the initial CNV, show an overall left frontal activation-negativity in controls in all tasks and a relative inhibition-positivity in schizophrenics (Figure 3). The effect was most pronounced for the Phonological task in which controls exhibited the largest left frontal activation and schizophrenics instead had inverted hemispherical pattern.


Schizophrenia as failure of left hemispheric dominance for the phonological component of language.

Angrilli A, Spironelli C, Elbert T, Crow TJ, Marano G, Stegagno L - PLoS ONE (2009)

Spline maps of scalp electrical activity (3/4 left frontal view evidencing areas involved in phonological elaboration) measured in the first second of the inter stimulus interval (iCNV), for the three linguistic tasks.Patients in the upper panel, controls in the lower panel. Negativity, in blue, indicates activation of cortical layers in this language-related CNV paradigm, positivity, in red, indicates relative inhibition.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2637431&req=5

pone-0004507-g003: Spline maps of scalp electrical activity (3/4 left frontal view evidencing areas involved in phonological elaboration) measured in the first second of the inter stimulus interval (iCNV), for the three linguistic tasks.Patients in the upper panel, controls in the lower panel. Negativity, in blue, indicates activation of cortical layers in this language-related CNV paradigm, positivity, in red, indicates relative inhibition.
Mentions: Spline maps of scalp electrical activity measured in the initial CNV, show an overall left frontal activation-negativity in controls in all tasks and a relative inhibition-positivity in schizophrenics (Figure 3). The effect was most pronounced for the Phonological task in which controls exhibited the largest left frontal activation and schizophrenics instead had inverted hemispherical pattern.

Bottom Line: The effect involved anterior (fronto-temporal) brain regions and was specific for the Phonological task; group differences were small or absent when subjects processed the same stimulus material in a Semantic task or during Word Recognition, i.e. during tasks that typically activate more widespread areas in both hemispheres.This loss of hemispheric dominance would explain typical symptoms, e.g. when an individual's own thoughts are perceived as an external intruding voice.The change can be interpreted as a consequence of "hemispheric indecision", a failure to segregate phonological engrams in one hemisphere.

View Article: PubMed Central - PubMed

Affiliation: Department of General Psychology, University of Padova, Padova, Italy. alessandro.angrilli@unipd.it

ABSTRACT

Background: T. J. Crow suggested that the genetic variance associated with the evolution in Homo sapiens of hemispheric dominance for language carries with it the hazard of the symptoms of schizophrenia. Individuals lacking the typical left hemisphere advantage for language, in particular for phonological components, would be at increased risk of the typical symptoms such as auditory hallucinations and delusions.

Methodology/principal findings: Twelve schizophrenic patients treated with low levels of neuroleptics and twelve matched healthy controls participated in an event-related potential experiment. Subjects matched word-pairs in three tasks: rhyming/phonological, semantic judgment and word recognition. Slow evoked potentials were recorded from 26 scalp electrodes, and a laterality index was computed for anterior and posterior regions during the inter stimulus interval. During phonological processing individuals with schizophrenia failed to achieve the left hemispheric dominance consistently observed in healthy controls. The effect involved anterior (fronto-temporal) brain regions and was specific for the Phonological task; group differences were small or absent when subjects processed the same stimulus material in a Semantic task or during Word Recognition, i.e. during tasks that typically activate more widespread areas in both hemispheres.

Conclusions/significance: We show for the first time how the deficit of lateralization in the schizophrenic brain is specific for the phonological component of language. This loss of hemispheric dominance would explain typical symptoms, e.g. when an individual's own thoughts are perceived as an external intruding voice. The change can be interpreted as a consequence of "hemispheric indecision", a failure to segregate phonological engrams in one hemisphere.

Show MeSH
Related in: MedlinePlus