Behavioural and fMRI evidence of semantic categorisation deficits in schizophrenia
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1
Swinburne University, Australia
Abnormalities in semantic processing are commonly proposed to be central to cognitive abnormalities and thought disturbances in schizophrenia (SZ). This investigation completed two studies in SZ which: 1) investigated behavioural categorisation ability and 2) examined the underlying neural substrates involved during categorisation; both studies extended this inquiry into bipolar disorder (BD) patients. A categorisation task was used that consisted of categories with five different exemplar words (i.e. high frequency, low frequency, borderline, related but outside category and unrelated). Participants were asked to indicate whether exemplars were or were not part of the category. Study 1 included 32 SZ patients, 28 BD (Type 1) patients and 32 healthy controls (HC) and examined behavioural performance. Study 2 included 10 SZ, 10 BD and 16 HC. These participants performed that task during fMRI. Behaviourally, patients had most difficulty categorising related words whilst HC had most difficulty with borderline examples; with both patient groups showing reduced accuracy and increased reaction times. There were no behavioural differences between patient groups. Categorisation ability in HC was related to activity in the left and right inferior frontal, left and right middle temporal gyrus, left hippocampus, left precuneus, anterior cingulate and the cerebellum. No above threshold activation was observed for patients. Examination of the interaction between task and group illustrated the patients exhibited hypo-activation within left frontal cortices, the left hippocampus and posterior temporal cortex. This data revealed both patient groups show difficulty with categorising semantic information. The fMRI data revealed impairments in the distributed frontal-temporal network during this task. This network is known to be engaged in the representation and processing of meaning of words, text, and discourse. Significantly, these deficits crossed diagnostic boundaries.
Keywords:
Schizophrenia,
functional MRI,
categorisation,
Semantic Processing,
fronto-temporal network
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Language
Citation:
Rossell
S and
Hughes
M
(2015). Behavioural and fMRI evidence of semantic categorisation deficits in schizophrenia.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00366
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Prof. Susan Rossell, Swinburne University, Melbourne, Australia, srossell@srossell.com