The Role of Gamma Oscillations During Integration of Metaphoric Gestures and Abstract Speech

Metaphoric (MP) co-speech gestures are commonly used during daily communication. They communicate about abstract information by referring to gestures that are clearly concrete (e.g., raising a hand for “the level of the football game is high”). To understand MP co-speech gestures, a multisensory integration at semantic level is necessary between abstract speech and concrete gestures. While semantic gesture-speech integration has been extensively investigated using functional magnetic resonance imaging, evidence from electroencephalography (EEG) is rare. In the current study, we set out an EEG experiment, investigating the processing of MP vs. iconic (IC) co-speech gestures in different contexts, to reveal the oscillatory signature of MP gesture integration. German participants (n = 20) viewed video clips with an actor performing both types of gestures, accompanied by either comprehensible German or incomprehensible Russian (R) speech, or speaking German sentences without any gestures. Time-frequency analysis of the EEG data showed that, when gestures were accompanied by comprehensible German speech, MP gestures elicited decreased gamma band power (50–70 Hz) between 500 and 700 ms in the parietal electrodes when compared to IC gestures, and the source of this effect was localized to the right middle temporal gyrus. This difference is likely to reflect integration processes, as it was reduced in the R language and no-gesture conditions. Our findings provide the first empirical evidence suggesting the functional relationship between gamma band oscillations and higher-level semantic processes in a multisensory setting

A rating scale for the assessment of objective and subjective formal thought and language disorder (TALD)

Formal thought disorder (FTD) is a core syndrome of schizophrenia. However, patients with other diagnoses, such as mania and depression amongst others, also present with FTD. We introduce a novel, comprehensive clinical rating scale, capturing the full variety of FTD phenomenology including subjective experiences. The 30-item Thought and Language Disorder (TALD) scale is based on a detailed review of the literature, encompassing all formal thought disorder symptoms reported from the early 20th century onwards. Objectively observable symptoms as well as subjective phenomena were included. Two hundred and ten participants (146 patients ICD-10 diagnoses: depression n. = 63, schizophrenia n. = 63, mania n. = 20; 64 healthy control subjects) were interviewed and symptoms rated with the TALD, TLC, HAMD, YMRS and SAPS/SANS. A principal component analyses was performed for the TALD to differentiate sub-syndromes. The principal component analysis revealed four FTD factors; objective and subjective as well as positive and negative factor dimensions. The correlation analyses with the TLC and the SAPS/SANS FTD sub-scores demonstrated the factor validity for the objective factors. The different diagnoses showed a distinct pattern of symptom severity in each of the factors, with mania patients exhibiting the highest value in the positive, objective dimension. The scale showed good psychometric results, which makes it a practicable, nosologically-open instrument for the detailed assessment of all FTD dimensions. The results strengthen the importance of subjective symptom assessment reported by the patient.DFG (project no. Ki 588/6-1)Scopu

Is formal thought disorder in schizophrenia related to structural and functional aberrations in the language network? A systematic review of neuroimaging findings

Formal thought disorder (FTD) is a core feature of schizophrenia, a marker of illness severity and a predictor of outcome. The underlying neural mechanisms are still a matter of debate. This study aimed at 1) reviewing the literature on the neural correlates of FTD in schizophrenia, and 2) testing the hypothesis that FTD correlates with structural and functional aberrations in the language network. Medline, PsychInfo, and Embase were searched for neuroimaging studies, which applied a clinical measure to assess FTD in adults with schizophrenia and were published in English or German in peer-reviewed journals until December 2016. Of 412 articles identified, 61 studies were included in the review. Volumetric studies reported bilateral grey matter deficits (L > R) to be associated with FTD in the inferior frontal gyrus, the superior temporal gyrus and the inferior parietal lobe. The same regions showed hyperactivity in resting state functional magnetic resonance imaging (fMRI) studies and both hyper- and hypoactivity in fMRI studies that employed semantic processing or free speech production tasks. Diffusion tensor imaging studies demonstrated white matter aberrations in fibre tracts that connect the frontal and temporo-parietal regions. FTD in schizophrenia was found to be associated with structural and functional aberrations in the language network. However, there are studies that did not find an association between FTD and neural aberrations of the language network and regions not included in the language network have been associated with FTD. Thus, future research is needed to clarify the specificity of the language network for FTD in schizophrenia

Differences in single positive formal thought disorder symptoms between closely matched acute patients with schizophrenia and mania

Formal thought disorders (FTD) are a hallmark diagnostic feature of schizophrenia (SZ) and (bipolar) mania (MA). FTD can be separated into positive (pFTD) and negative dimensions. It is unclear whether there are differences in pFTD on a single symptom level between acutely ill patients with SZ and MA, which cannot be attributed to cognitive impairment. We compared single pFTD symptoms in two groups of acutely ill patients with ICD-10 bipolar mania and schizophrenia, closely matched for age, sex, pFTD TALD score, verbal IQ and neuropsychological test performance (executive function, verbal fluency, attention, and working memory). SZ patients had higher severity of the TALD symptoms 'perseverations' and 'poverty of content of speech' than those with MA (Mann-Whitney U, significant, Bonferroni corrected). Speech in acute SZ patients differs from MA in that it conveys little information and adheres to previously mentioned ideas and topics. Matching for confounding variables, such as IQ and cognition, is important when comparing patients with different diagnoses

How the use of segmentation signs in compound reading affects reading behavior: an eye-tracking study

Two eye-tracking experiments were conducted to investigate the effects of visual segmenta-tion, complexity, and context on the cognitive processing of compounds in German Easy Language. By presenting compounds in different boundary conditions, we determined whether a segmentation cue facilitates the processing of compounds presented with and without contextual information. The study was conducted with unimpaired adults and with hearing-impaired pupils, representing one of the target groups of Easy Language. The results indicate that visual segmentation facilitates processing of compounds for pupils with low literacy skills. However, they only benefit from segmentation when morpheme boundaries are marked in a subtle way, i.e., without strikingly deviating from the standard version. Pupils with higher literacy skills and unimpaired adults do not profit from segmentation. Even though hyphenation slows down compound processing for unimpaired readers, initial processing advantages of hyphenated over concatenated compounds emerged, which is explained by the fact that hyphenation forces a morpheme-based access and enables fast recognition of the compound’s first constituent. However, it hinders readers from accessing the compound via the direct route and thus slows down the processing of the compound as a whole. Furthermore, unimpaired readers and hearing-impaired pupils process compounds faster when presented with context

The role of semantic abstractness and perceptual category in processing speech accompanied by gestures

Space and shape are distinct perceptual categories. In language, perceptual information can also be used to describe abstract semantic concepts like a ‘rising income’ (space) or a ‘square personality’ (shape). Despite being inherently concrete, co-speech gestures depicting space and shape can accompany concrete or abstract utterances. Here, we investigated the way that abstractness influences the neural processing of the perceptual categories of space and shape in gestures. Thus, we tested the hypothesis that the neural processing of perceptual categories is highly dependent on language context.In a two-factorial design, we investigated the neural basis for the processing of gestures containing shape (SH) and spatial information (SP) when accompanying concrete (c) or abstract (a) verbal utterances. During fMRI data acquisition participants were presented with short video clips of the four conditions (cSP, aSP, cSH, aSH) while performing an independent control task.Abstract (a) as opposed to concrete (c) utterances activated temporal lobes bilaterally and the left inferior frontal gyrus (IFG) for both shape-related (SH) and space-related (SP) utterances. An interaction of perceptual category and semantic abstractness in a more anterior part of the left IFG and inferior part of the posterior temporal lobe indicates that abstractness strongly influenced the neural processing of space and shape information. Despite the concrete visual input of co-speech gestures in all conditions, space and shape information is processed differently depending on the semantic abstractness of its linguistic context

The role of the left and right inferior frontal gyrus in processing metaphoric and unrelated co-speech gestures

Gestures are an integral part of in-person conversations and complement the meaning of the speech they accompany. The neural processing of co-speech gestures is supported by a mostly left-lateralized network of fronto-temporal regions. However, in contrast to iconic gestures, metaphoric as well as unrelated gestures have been found to more strongly engage the left and right inferior frontal gyrus (IFG), respectively. With this study, we conducted the first systematic comparison of all three types of gestures and resulting potential laterality effects.During collection of functional imaging data, 74 subjects were presented with 5 s videos of abstract speech with related metaphoric gestures, concrete speech with related iconic gestures and concrete speech with unrelated gestures. They were asked to judge whether the content of the speech and gesture matched or not.Differential contrasts revealed that both abstract related and concrete unrelated compared to concrete related stimuli elicited stronger activation of the bilateral IFG. Analyses of lateralization indices for IFG activation further showed a left hemispheric dominance for metaphoric gestures and a right hemispheric dominance for unrelated gestures.Our results give support to the hypothesis that the bilateral IFG is activated specifically when processing load for speech-gesture combinations is high. In addition, laterality effects indicate a stronger involvement of the right IFG in mismatch detection and conflict processing, whereas the left IFG performs the actual integration of information from speech and gesture

Psychiatric symptoms are differentially associated with verbal fluency performance in patients with schizophrenia and affective disorders

Background Despite verbal fluency (VF) being a common task in psychiatric research, there is very little consensus on the nature of VF deficits in psychiatric populations and their implications for our knowledge about cognitive and specifically linguistic functioning in these populations. Previous studies have found that negative symptoms, including alogia, are associated with poorer overall VF production in patients with schizophrenia (SCH), while studies investigating positive symptoms, including formal thought disorder, have yielded mixed results. Because most studies didn’t analyze additional VF measures such as clustering and lexical characteristics, it remains unclear whether the association between negative and positive symptoms and VF performance in patients with schizophrenia reflects abnormalities in linguistic and/or semantic processing or other aspects of cognition. Furthermore, it is uncertain whether these associations are specific to patients with schizophrenia, while the associations with manic and depressive symptoms are understudied. Methods We recruited 58 German-speaking inpatients diagnosed with either schizophrenia (N = 36), bipolar disorder (BD; N = 10), or major depression (DEP; N = 12). All patients were assessed on conventional symptom scales including the SANS/SAPS, HAMD, and YMRS, and were further administered the semantic (SF; animals) and letter (LF; P) fluency tasks (60 s). The following dependent variables were analyzed: correct words, error rate, response latencies, switching rate, cluster size, idiosyncratic word production rate, and word frequency. Results BD produced significantly larger clusters and had significantly higher idiosyncratic word production rates on SF compared to both SCH and DEP, while overall word frequency on SF differentiated between all patient groups. Overall negative symptomatology and specifically alogia were negatively associated with overall performance and positively with between-cluster response latencies on SF. Alogia was not significantly associated with other VF variables. Cluster size and overall word frequency on SF were positively associated with depressive and negatively with manic symptoms, idiosyncratic word production rate on SF was positively associated with manic symptoms, while positive symptoms were only negatively associated with the frequency of the first three words on SF. Discussion Previous evidence for an association between negative and positive symptoms, and VF performance in SCH has been to some extent replicated in a diverse psychiatric sample. Because alogia was not significantly associated with VF variables other than overall productivity and between-cluster response latencies, we found no evidence that alogia is associated with deficient processing within the semantic memory or mental lexicon. Yet, its positive association with between-cluster response latencies possibly suggests that alogia reflects transdiagnostic dysfunctional connectivity between the prefrontal and temporal cortices and, thus, inefficient lexical access. Furthermore, clinical levels of mania were associated with normal cluster sizes, in line with one previous study. Intriguingly, cluster sizes did not differ between SCH and DEP, indicating a similar level of the semantic deficit with possibly different underlying mechanisms. Additionally, manic symptoms were associated with relatively unusual (but appropriate) word production, indicating aberrant saliency of words during lexical access in mania. Further research regarding word frequency is needed to adequately interpret those results. Finally, LF performance was diagnostically and symptomatically unremarkable

MIST - Metaphors for Internal States

A database for German metaphorical expressions conveying internal states with human senses as their source domains. 168 metaphorical expressions from the source domains vision, hearing, smell, taste, touch, and temperature combined with literal equivalents were collected and rated by 643 adults on the psycholinguistic & affective variables agreement, valence, arousal, and familiarity. Update: The original database was extended by 168 additional stimuli from the source domains body/interoception, force, orientation/direction, path, animal, technology, and home living. Additionally, 100 controlled audio files of the stimuli are freely available. For information on the additional stimuli please visit the database's website: https://www.uni-marburg.de/de/fb09/igs/arbeitsgruppen/klinische-linguistik/forschung/projekte/mist_databas