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Associative semantic network dysfunction in thought-disordered schizophrenic patients: direct evidence from indirect
Biological Psychiatry
|December 15, 1993
Summary
Schizophrenia patients with thought disorder show faster and wider semantic activation spread in associative networks. This suggests impaired semantic associative memory, possibly due to lower signal-to-noise ratios in the brain.
Area of Science:
- Cognitive Psychology
- Neuroscience
- Psychiatry
Background:
- Semantic associative networks are crucial for cognition.
- Thought disorder in schizophrenia is linked to cognitive deficits.
- Dopamine's role in neural signal-to-noise ratio is under investigation.
Purpose of the Study:
- To examine semantic activation spread in schizophrenia.
- To compare thought-disordered (TD) and non-thought-disordered (NTD) patients with controls.
- To identify reliable indicators of associative network dysfunction.
Main Methods:
- Lexical decision task assessing direct and indirect semantic priming.
- Varying stimulus onset asynchronies (SOA) and semantic distances.
- Comparison of TD schizophrenic patients, NTD schizophrenic patients, and normal controls.
Main Results:
- Semantic associations spread significantly further and faster in TD schizophrenic patients.
- Indirect semantic priming at short SOAs effectively indicated associative network dysfunction.
- TD schizophrenic patients demonstrated a lower signal-to-noise ratio in semantic associative memory.
Conclusions:
- Thought-disordered schizophrenia is characterized by aberrant semantic activation.
- Indirect semantic priming is a sensitive marker for cognitive deficits in schizophrenia.
- Findings support the hypothesis of reduced neural signal-to-noise ratio in TD schizophrenia.