Isn’t it ironic? Neural Correlates of Irony Comprehension in Schizophrenia

Abstract

Ironic remarks are frequent in everyday language and represent an important form of social cognition. Increasing evidence indicates a deficit in comprehension in schizophrenia. Several models for defective comprehension have been proposed, including possible roles of the medial prefrontal lobe, default mode network, inferior frontal gyri, mirror neurons, right cerebral hemisphere and a possible mediating role of schizotypal personality traits. We investigated the neural correlates of irony comprehension in schizophrenia by using event-related functional magnetic resonance imaging (fMRI). In a prosody-free reading paradigm, 15 female patients with schizophrenia and 15 healthy female controls silently read ironic and literal text vignettes during fMRI. Each text vignette ended in either an ironic (n = 22) or literal (n = 22) statement. Ironic and literal text vignettes were matched for word frequency, length, grammatical complexity, and syntax. After fMRI, the subjects performed an off-line test to detect error rate. In this test, the subjects indicated by button press whether the target sentence has ironic, literal, or meaningless content. Schizotypal personality traits were assessed using the German version of the schizotypal personality questionnaire (SPQ). Patients with schizophrenia made significantly more errors than did the controls (correct answers, 85.3% vs. 96.3%) on a behavioural level. Patients showed attenuated blood oxygen level-dependent (BOLD) response during irony comprehension mainly in right hemisphere temporal regions (ironic>literal contrast) and in posterior medial prefrontal and left anterior insula regions (for ironic>visual baseline, but not for literal>visual baseline). In patients with schizophrenia, the parahippocampal gyrus showed increased activation. Across all subjects, BOLD response in the medial prefrontal area was negatively correlated with the SPQ score. These results highlight the role of the posterior medial prefrontal and right temporal regions in defective irony comprehension in schizophrenia and the mediating role of schizotypal personality traits.

Cognition and Brain Function in Schizotypy: A Selective Review

“…27,97,98 Besides odd speech and thought disorder, individuals with elevated schizotypy show differences in correct production and interpretation of nonliteral language such as metaphors, 99 irony, 80,99,100 fauxpas, 101 and proverbs, 102 similar to schizophrenia and autism. While nonliteral language comprehension problems seem correlated with schizotypy across the spectrum, 80,102 the association in nonclinical schizotypy is subtle 103 or even controversial, 100,104 but still detectable on the neural level. 105 A number of mechanisms may contribute to these deficits, 106 including semantic association differences, [107][108][109] aberrant semantic priming mechanisms, 106 and inadequate context integration.…”

“…78 Neuroimaging evidence for these aberrant laterality patterns have been published recently. 79,80 In summary, there is plenty of evidence showing that attention (selection and inhibition), WM and memory is reduced in schizotypy. There is evidence for both deficits in individuals with psychometrically identified schizotypy relative to individuals with low levels of schizotypal traits, as well as evidence for associations between specific deficits and specific schizotypal dimensions.…”

“…105 A number of mechanisms may contribute to these deficits, 106 including semantic association differences, [107][108][109] aberrant semantic priming mechanisms, 106 and inadequate context integration. 110,111 Most likely both cerebral hemispheres contribute to language differences associated with elevated schizotypy, 80,105 with the right hemisphere thought to play an important role in loosening of associations and pragmatic language deficits in schizotypy. 99,103 Left fronto-temporal language network abnormalities may also explain language differences in schizotypy.…”

An examination of the language construct in NIMH's research domain criteria: Time for reconceptualization!

“…The neural bases of higher order language perception abilities have also been examined. For example, linguistic irony, which is a metacognitive and social cognitive function, is reported to be disrupted in many psychiatric conditions, including schizophrenia and autism [Rapp et al, ; Rapp et al, ; Varga et al, ]. These studies have indicated involvement of posterior medial prefrontal and right temporal regions in the defective irony comprehension in schizophrenia, together with an association between activation in these regions and schizotypal personality traits [Rapp et al, ].…”

Figurative Language Comprehension in Schizophrenia and Its Neural Basis

“…The condition seems to be more complicated in schizophrenic patients for they have abnormal lateralization (Kircher, Leube, Erb, Grodd, & Rapp, 2007;Mashal, Vishne, Laor, & Titone, 2013). Rapp et al (2013) carried out an experiment in which 15 SPs and 15 healthy participants were involved and they were all female. The participants were asked to read irony and their brain activation had been recorded.…”