N400 and automatic semantic processing abnormalities in patients with schizophrenia.

Full Abstract

BACKGROUND:
One factor hypothesized to underlie thinking disturbance in patients with schizophrenia is abnormal or disinhibited automatic spreading activation of semantic networks, which can be assessed using the N400 event-related potential. N400 is a negative-going component elicited at about 400 milliseconds following semantic stimuli that are not primed by the preceding context. Semantic priming refers to facilitated semantic processing gained through preexposure to semantic context, which can happen automatically or strategically. Using N400, inferences can be drawn regarding the extent to which a given context primes a word.

METHODS:
During a picture-word matching task, N400s to primed (exact match) and unprimed (remotely related) words were recorded from 18 healthy control subjects and 18 patients with schizophrenia performing a picture-word matching task. A short interval (325 milliseconds) between picture and word onset (stimulus-onset asynchrony) was used to optimize the role of automatic spreading semantic activation and to minimize the role of attention, expectancy, preparation, and working memory.

RESULTS:
Despite behavioral evidence of normal semantic priming, patients generated an abnormally small N400 (ie, less negative) to unprimed words. The N400 to primed words was neither larger nor smaller in patients than in controls, suggesting normal use of context.

CONCLUSIONS:
A reduced N400 to unprimed words in patients with schizophrenia suggests that there was inappropriate priming of words by remotely related semantic contexts. This is consistent with an overly broad automatic spread of activation through semantic networks in patients with schizophrenia.

Learn Faster Today Improve your study skills

Author information

Author/s: Mathalon, Daniel H (DH); Faustman, William O (WO); Ford, Judith M (JM);

Affiliation: Department of Psychiatry, VA Connecticut Healthcare System, West Haven 06516, USA. daniel.mathalon(-atsign-)yale.edu

Grants: MH40052 (Agency:NIMH NIH HHS) ; MH58262 (Agency:NIMH NIH HHS)

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.

Journal: Archives of general psychiatry (Arch Gen Psychiatry), published in United States. (Language: eng)

Reference: 2002-Jul; vol 59 (issue 7) : pp 641-8

Dates: Created 2002/07/01; Completed 2002/08/06; Revised 2007/11/14;

PMID: 12090817, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article (including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Brain - physiopathology
Brief Psychiatric Rating Scale
Electroencephalography - statistics & numerical data
Evoked Potentials - physiology
Female
Form Perception - physiology
Humans
Male

Male
Middle Aged
Psychomotor Performance - physiology
Reaction Time - physiology
Reading
Schizophrenia - diagnosis; physiopathology
Schizophrenic Psychology
Semantics
Speech Perception - physiology

These are the highest related articles currently in the database:

See 100+ related articles.