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Apraxia is an umbrella term for different disorders of higher motor abilities that are not explained by elementary sensorimotor deficits (e. g. paresis or ataxia). Characteristic features of apraxia that are easy to recognize in clinical practice are difficulties in pantomimed or actual use of tools as well as in imitation of meaningless gestures. Apraxia is bilateral, explaining the cognitive motor disorders and occurs frequently (but not exclusively) after left hemispheric lesions, as well as in neurodegenerative diseases, such as corticobasal syndrome and Alzheimer's disease. Apraxic deficits can seriously impair activities of daily living, which is why the appropriate diagnosis is of great relevance. At the functional anatomical level, different cognitive motor skills rely on at least partly different brain networks, namely, a ventral processing pathway for semantic components, such as tool-action associations, a ventro-dorsal pathway for sensorimotor representations of learnt motor acts, as well as a dorso-dorsal pathway for on-line motor control and, probably, imitation of meaningless gestures. While these networks partially overlap with language-relevant regions, more clear cut dissociations are found between apraxia deficits and disorders of spatial attention. In addition to behavioral interventions, noninvasive neuromodulation approaches, as well as human-computer interface assistance systems are a growing focus of interest for the treatment of apraxia. [ABSTRACT FROM AUTHOR]

Background: Chronic pain is a common non-motor symptom in patients with Parkinson's disease (PD). Aim: To facilitate the diagnosis of pain in PD, we developed a new classification system the Parkinson's disease pain classification system (PD-PCS) and translated the corresponding validated questionnaire into German. Methods: A causal relationship of the respective pain syndrome with PD can be determined by four questions before assigning it hierarchically into one of three pain categories (neuropathic, nociceptive and nociplastic). Results: In the initial validation study 77% of the patients (122/159) had PD-associated pain comprising 87 (55%) with nociceptive, 36 (22%) with nociplastic and 24 (16%) with neuropathic pain. The study revealed a high validity of the questionnaire and a moderate intrarater and interrater reliability. The questionnaire has been adapted into German and employed in 30 patients. Discussion: The PD-PCS questionnaire is a valid and reliable tool to determine the relationship of a pain syndrome with PD before classifying it according to the underlying category, facilitating further diagnostics and treatment. [ABSTRACT FROM AUTHOR]

Background: Valid assessment of apraxia in usually non-apraxic Parkinson's disease helps to delineate atypical parkinsonism frequently associated with apraxia. Furthermore, in a subgroup of late Parkinson's disease apraxia, typically the ideomotor subtype, may gradually superimpose onto parkinsonian motor symptoms contributing to defective manual skill. Here we evaluate the utility of a brief, standardized test, the apraxia screen of TULIA (AST).Methods: Seventy five Parkinson's disease patients were tested with the AST. Parkinsonian motor deficits were measured using Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III and difficulties in activities of daily living (ADL) by modified MDS-UPDRS part II (eating, dressing, personal hygiene, and writing).Results: No association was found between the AST and MDS-UPDRS part III, indicating that AST discriminates well (discriminative validity) between apraxia and parkinsonism. Furthermore, AST was associated with ADL and Hoehn & Yahr stage (convergent validity).Conclusions: AST is a short and valid test to rule out or detect apraxia in Parkinson's disease. [ABSTRACT FROM AUTHOR]

Deficient inhibitory control leading to perseverative behaviour is often observed in neglect patients. Previous studies investigating the relationship between response inhibition and visual attention have reported contradictory results: some studies found a linear relationship between neglect severity and perseverative behaviour whereas others could not replicate this result. The aim of the present study was to shed further light on the interplay between visual attention and response inhibition in neglect, and to investigate the neural underpinnings of this interplay. We propose the use of the Five-Point Test, a test commonly used to asses nonverbal fluency, as a novel approach in the context of neglect. In the Five-Point Test, participants are required to generate as many different designs as possible, by connecting dots within forty rectangles. We hypothesised that, because of its clear definition of perseverative errors, the Five-Point Test would accurately assess both visual attention as well as perseverative behaviour. We assessed 46 neglect patients with right-hemispheric stroke, and performed voxel-based lesion-symptom mapping (VLSM) to identify neural substrates of perseverative behaviour as well as the spatial distribution of perseverations. Our results showed that the Five-Point Test can reliably measure neglect and perseverative behaviour. We did not find any significant relationship between neglect severity and the frequency of perseverations. However, within the subgroup of neglect patients who displayed perseverative behaviour, the spatial distribution of perseverations significantly depended on the integrity of the right putamen. We discuss the putative role of the putamen as a potential subcortical hub to modulate the complex integration between visual attention and response inhibition processes. [ABSTRACT FROM AUTHOR]

Objective Formal thought disorder (FTD) is a core symptom in schizophrenia. Here, we focus on resting state cerebral blood flow (rCBF) linked to dimensions of FTD. Methods We included 47 schizophrenia spectrum patients and 30 age- and gender-matched healthy controls. We assessed FTD with the assessment of thought, language, and communication (TLC) and imaging on a 3T MRI scanner. Within patients, we tested the association of FTD dimensions and in a subgroup ( n = 27) the association of functional outcome after 6 months with whole brain rCBF. Results Negative FTD was most prominently associated with perfusion within the superior temporal gyrus, while positive FTD was associated with perfusion within the supplementary motor area, and inferior frontal gyrus. Perfusion within the left supramarginal gyrus was associated with social functioning after 6 months. Conclusions Distinguishable associations of rCBF with FTD dimensions point to distinct underlying pathophysiology. The location of aberrant perfusion patterns suggests that negative FTD might reflect defective access to semantic memory while positive FTD likely reflects defective suppression of irrelevant information during increased speech production. Finally, the neural correlates of thought block were also predictive of poor functional outcome. Thus, functional outcome and distinct FTD dimensions may share some pathophysiology. [ABSTRACT FROM AUTHOR]

Background and purpose Impaired dexterity (fine hand movements) is often present in Parkinson's disease ( PD), even at early to moderate disease stages. It has a detrimental impact on activities of daily living ( ADL) such as buttoning, contributing to reduced quality of life. Limb-kinetic apraxia, a loss of the ability to make precise, independent but coordinated finger and hand movements, may contribute to impaired dexterity even more than bradykinesia per se. However, the impact of limb-kinetic apraxia on ADL remains controversial. Our aim was to identify the strongest predictor of buttoning and unbuttoning in PD. It was hypothesized that coin rotation (a surrogate of limb-kinetic apraxia) represents the most important determinant. Methods Sixty-four right-handed, early to moderate PD patients were recruited from three movement disorder centers (Hoehn andYahr stages 1-3). Buttoning, unbuttoning and coin rotation (right and left hand) represented the target tasks. Motor impairment was assessed according to the Unified Parkinson's Disease Rating Scale. Results Multiple linear regression analysis showed that coin rotation with the right hand was the only significant predictor of buttoning ( P < 0.001) and unbuttoning ( P = 0.002). Notably, measures of bradykinesia or overall motor impairment did not represent significant predictors. Conclusions Constituting the novel key finding, limb-kinetic apraxia seems to be particularly relevant for ADL requiring dexterity skills in PD, even at early to moderate disease stages. Our results prompt research into the pathophysiological background and therapeutic options to treat limb-kinetic apraxia. The simple coin rotation test provides valuable information about ADL-related dexterity skills. [ABSTRACT FROM AUTHOR]

A controversial concept suggests that impaired finger dexterity in Parkinson's disease may be related to limb kinetic apraxia that is not explained by elemental motor deficits such as bradykinesia. To explore the nature of dexterous difficulties, the aim of the present study was to assess the relationship of finger dexterity with ideomotor praxis function and parkinsonian symptoms. Twenty-five patients with Parkinson's disease participated in the study. Their left and right arms were tested independently. Testing was done in an OFF and ON state as defined by a modified version of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Finger dexterity was assessed by a coin rotation (CR) task and ideomotor praxis using a novel test of upper limb apraxia (TULIA), in which the patients were requested to imitate and pantomime 48 meaningless, as well as communicative and tool-related gestures. Coin rotation significantly correlated with TULIA irrespective of the motor state and arm involved, but not with the MDS-UPDRS. This association was significantly influenced by Hoehn and Yahr stage. The strong association of finger dexterity with praxis function but not the parkinsonian symptoms indicates that impaired finger dexterity in Parkinson's disease may be indeed apraxic in nature, yet, predominantly in advanced stages of the disease when cortical pathology is expected to develop. The findings are discussed within a cognitive-motor model of praxis function. [ABSTRACT FROM AUTHOR]

Abstract: A controversial concept suggests that impaired finger dexterity in Parkinson’s disease may be related to limb kinetic apraxia that is not explained by elemental motor deficits such as bradykinesia. To explore the nature of dexterous difficulties, the aim of the present study was to assess the relationship of finger dexterity with ideomotor praxis function and parkinsonian symptoms. Twenty-five patients with Parkinson’s disease participated in the study. Their left and right arms were tested independently. Testing was done in an OFF and ON state as defined by a modified version of the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS). Finger dexterity was assessed by a coin rotation (CR) task and ideomotor praxis using a novel test of upper limb apraxia (TULIA), in which the patients were requested to imitate and pantomime 48 meaningless, as well as communicative and tool-related gestures. Coin rotation significantly correlated with TULIA irrespective of the motor state and arm involved, but not with the MDS-UPDRS. This association was significantly influenced by Hoehn and Yahr stage. The strong association of finger dexterity with praxis function but not the parkinsonian symptoms indicates that impaired finger dexterity in Parkinson’s disease may be indeed apraxic in nature, yet, predominantly in advanced stages of the disease when cortical pathology is expected to develop. The findings are discussed within a cognitive-motor model of praxis function. [Copyright &y& Elsevier]

Background Focal spasticity is a significant motor disorder following stroke, and Botulinum Toxin Type-A (BoNT-A) is a useful treatment for this. The authors evaluated kinematic modifications induced by spasticity, and whether or not there is any improvement following injection of BoNT-A. Methods Eight patients with stroke with upper-limb spasticity, showing a flexor pattern, were evaluated using kinematics before and after focal treatment with BoNT-A. A group of sex- and age-matched normal volunteers acted as a control group. Results Repeated-measures ANOVA showed that patients with stroke performed more slowly than the control group. Following treatment with BoNT-A, there was a significant improvement in kinematics in patients with stroke, while in the control group, performance remained unchanged. Conclusions Focal treatment of spasticity with BoNT-A leads to an adaptive change in the upper limb of patients with spastic stroke. [ABSTRACT FROM AUTHOR]

Background: Only few standardized apraxia scales are available and they do not cover all domains and semantic features of gesture production. Therefore, the objective of the present study was to evaluate the reliability and validity of a newly developed test of upper limb apraxia (TULIA), which is comprehensive and still short to administer. Methods: The TULIA consists of 48 items including imitation and pantomime domain of non-symbolic (meaningless), intransitive (communicative) and transitive (tool related) gestures corresponding to 6 subtests. A 6-point scoring method (0–5) was used (score range 0–240). Performance was assessed by blinded raters based on videos in 133 stroke patients, 84 with left hemisphere damage (LHD) and 49 with right hemisphere damage (RHD), as well as 50 healthy subjects (HS). Results: The clinimetric findings demonstrated mostly good to excellent internal consistency, inter- and intra-rater (test–retest) reliability, both at the level of the six subtests and at individual item level. Criterion validity was evaluated by confirming hypotheses based on the literature. Construct validity was demonstrated by a high correlation ( r = 0.82) with the De Renzi-test. Conclusion: These results show that the TULIA is both a reliable and valid test to systematically assess gesture production. The test can be easily applied and is therefore useful for both research purposes and clinical practice. [ABSTRACT FROM AUTHOR]

Abstract: Background: Valid assessment of apraxia in usually non-apraxic Parkinson’s disease helps to delineate atypical parkinsonism frequently associated with apraxia. Furthermore, in a subgroup of late Parkinson’s disease apraxia, typically the ideomotor subtype, may gradually superimpose onto parkinsonian motor symptoms contributing to defective manual skill. Here we evaluate the utility of a brief, standardized test, the apraxia screen of TULIA (AST). Methods: Seventy five Parkinson’s disease patients were tested with the AST. Parkinsonian motor deficits were measured using Movement Disorders Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III and difficulties in activities of daily living (ADL) by modified MDS-UPDRS part II (eating, dressing, personal hygiene, and writing). Results: No association was found between the AST and MDS-UPDRS part III, indicating that AST discriminates well (discriminative validity) between apraxia and parkinsonism. Furthermore, AST was associated with ADL and Hoehn & Yahr stage (convergent validity). Conclusions: AST is a short and valid test to rule out or detect apraxia in Parkinson’s disease. [Copyright &y& Elsevier]

Introduction Schizophrenia patients frequently suffer from complex motor abnormalities including fine and gross motor disturbances, abnormal involuntary movements, neurological soft signs and parkinsonism. These symptoms occur early in the course of the disease, continue in chronic patients and may deteriorate with antipsychotic medication ( Walther and Strik, 2012 ). Furthermore gesture performance is impaired in patients, including the pantomime of tool use. Whether schizophrenia patients would show difficulties of actual tool use has not yet been investigated. Human tool use is complex and relies on a network of distinct and distant brain areas. We therefore aim to test if schizophrenia patients had difficulties in tool use and to assess associations with structural brain imaging using voxel based morphometry (VBM) and tract based spatial statistics (TBSS). Methods In total, 44 patients with schizophrenia (DSM-5 criteria; 59% men, mean age 38) underwent structural MR imaging and performed the Tool-Use test ( Randerath et al., 2011 ). The test examines the use of a scoop and a hammer in three conditions: pantomime (without the tool), demonstration (with the tool) and actual use (with a recipient object). T1-weighted images were processed using SPM8 and DTI-data using FSL TBSS routines. To assess structural alterations of impaired tool use we first compared gray matter (GM) volume in VBM and white matter (WM) integrity in TBSS data of patients with and without difficulties of actual tool use. Next we explored correlations of Tool use scores and VBM and TBSS data. Group comparisons were family wise error corrected for multiple tests. Correlations were uncorrected ( p < 0.001) with a minimum cluster threshold of 17 voxels (equivalent to a map-wise false positive rate of alpha < 0.0001 using a Monte Carlo procedure). Results Tool use was impaired in schizophrenia (43.2% pantomime, 11.6% demonstration, 11.6% use). Impairment was related to reduced GM volume and WM integrity. Whole brain analyses detected an effect in the SMA in group analysis. Correlations of tool use scores and brain structure revealed alterations in brain areas of the dorso-dorsal pathway (superior occipital gyrus, superior parietal lobule, and dorsal premotor area) and the ventro-dorsal pathways (middle occipital gyrus, inferior parietal lobule) the action network, as well as the insula and the left hippocampus. Furthermore, significant correlations within connecting fiber tracts - particularly alterations within the bilateral corona radiata superior and anterior as well as the corpus callosum - were associated with Tool use performance. Conclusions Tool use performance was impaired in schizophrenia, which was associated with reduced GM volume in the action network. Our results are in line with reports of impaired tool use in patients with brain lesions particularly of the dorso-dorsal and ventro-dorsal stream of the action network. In addition an effect of tool use on WM integrity was shown within fiber tracts connecting regions important for planning and executing tool use. Furthermore, hippocampus is part of a brain system responsible for spatial memory and navigation.The results suggest that structural brain alterations in the common praxis network contribute to impaired tool use in schizophrenia ( Fig. 1 ). [ABSTRACT FROM AUTHOR]

Introduction Motor symptoms are an integral part of the clinical presentation of schizophrenia and disturbances of fine motor function are frequent. However, only limited knowledge exists on the neural correlates of fine motor skills in schizophrenia. We implemented a complex fine motor task to test associations with whole brain gray matter (GM) volume as well as cerebral blood flow (CBF). We aimed to investigate whether patients with difficulties of fine motor performance would show structural and cerebral blood flow alterations in the motor loop. Methods In total 42 schizophrenia patients (59.5% men, mean age = 38.6 ± 11.4) diagnosed according to DSM-V underwent MR-neuroimaging. All patients but four received antipsychotic treatment. Parkinsonism was assessed using the motor part of the Unified Parkinson Disease Rating Scale (UPDRS). Fine motor skills were assessed using the coin rotation task. The task is to rotate a coin (.5 swiss francs) using three fingers of the left hand (thumb, index, middle) through serial 180-degree turns as rapidly as possible. Deficits are indicated by the reduced number of half turns and coin drops. We processed structural images using standard SPM8 procedures, in particular voxel-based morphometry (VBM) toolbox. Resting state CBF was measured by arterial spin labeling (ASL). ASL data was analyzed with our custom written MATLAB programs ( Federspiel et al., 2006; Walther et al., 2011 ). The main emphasis was to explore the effect of task performance on GM volume and CBF. Correlations of task performance (mean = 10.7 ± 4.1) and GM volume (covariates total intracranial volume and UPDRS) as well as CBF (covariate UPDRS) were calculated. A threshold of p - uncorr < 0.001 (min. cluster size = 17: equivalent to a map-wise false positive rate of alpha < 0.0001 using a Monte Carlo procedure) was applied. Results We found significant correlations of coin rotation scores and GM volume in the bilateral pre-supplementary motor area (pre-SMA) extending to the SMA, in the left primary motor cortex, the right superior frontal gyrus, bilateral the cerebellum and the left putamen. The pre-SMA cluster survived family wise error correction at cluster level. Significant correlations of CBF and the coin rotation scores were detected in the right SMA, the left primary motor cortex and in the right superior frontal gyrus (Area Fp1), the left inferior frontal gyrus and the right precuneus. Two clusters survived family wise error correction: right superior frontal gyrus and the left inferior frontal gyrus. Discussion Difficulties of fine motor task performance were associated with structural gray matter volume reduction in the motor loop, particularly in cortical motor control areas. In addition fine motor function in schizophrenia patients was linked with cerebral blood flow. These findings were corrected for parkinsonism. In sum, the results argue for specific alterations of the motor system in schizophrenia as source of impaired fine motor function beyond parkinsonism. [ABSTRACT FROM AUTHOR]

Background Schizophrenia is associated with poor nonverbal communication. Impairments in the performance of hand gestures have been shown in 67% of patients with schizophrenia. These deficits are similar to those seen in Apraxia, which is often due to lesions in the inferior parietal (IPL) lobe, insula and inferior frontal gyrus (IFG). In Schizophrenia however, the neural correlates are unknown. Therefore, we investigated structural correlates of impaired gesture performance in schizophrenia. Methods In 43 patients with schizophrenia spectrum disorders, gesture performance was assessed by the comprehensive Test of Upper Limb Apraxia (TULIA). Performance was video recorded and blindly rated for accuracy. Structural brain imaging was measured in all patients using a 3-T MR Scanner. Grey matter density was correlated with TULIA scores using Whole-Brain Voxel-Based Morphometry (VBM) and total intracranial volume as covariate. White matter integrity was correlated with TULIA scores using Tract-Based Spatial Statistics (TBSS) and age as covariate. Results The TULIA total score correlated with grey matter density in several clusters of the praxis network at p < 0.05 FWE-corrected: bilateral the superior temporal lobe and the primary motor cortex, the left inferior frontal gyrus, the left superior occipital gyrus, the left inferior parietal lobe, the right insula, the supplementary motor area, middle cingulate cortex and anterior cingulate cortex as well as the left hippocampus. Poor gesture performance was associated with reduced grey matter density in these clusters. In addition white matter integrity correlated significant at p < 0.05 (corrected) with TULIA total score within the anterior cingulum and corona radiata bilaterally as well as left uncinate fasciculus. These clusters were located close to the anterior cingulate cortex cluster of the grey matter results. Conclusions Aberrant brain structure is associated with poor gesture performance in schizophrenia. Particularly in key regions of the praxis network, i.e. insula, parietal cortex, we detected correlations of gesture performance and grey and white matter markers. In addition, the anterior cingulate cortex grey matter was correlated to gesture performance, a region implicated in action planning and control. Therefore, specific brain structural alterations may contribute to deficits in nonverbal communication in schizophrenia ( Fig. 1 ). [ABSTRACT FROM AUTHOR]

Background Higher order processes such as recognition of gestures rely on a network of distinct and distant brain areas. Particularly the role of key regions such as the left inferior frontal gyrus (IFG) and the inferior parietal lobe is subject to ongoing debate. Schizophrenia patients suffer from impaired gesture performance and recognition. However, neural correlates of impaired gesture recognition have not yet been investigated. We therefore aim to test associations between structural brain imaging and postural knowledge in schizophrenia using voxel based morphometry (VBM) and tract based spatial statistics (TBSS). Methods In total, 44 patients with schizophrenia (DSM-5 criteria; 59% men, mean age 38) underwent structural MR imaging and performed the comprehensive postural knowledge task (PKT) for hand gestures. All patients except four were treated with antipsychotics. T1-weighted images were processed using SPM8 and DTI-data using FSL TBSS routines. We explored correlations of PKT scores and gray matter (GM) volume in VBM data and correlations of PKT scores and white matter (WM) integrity in TBSS data. Results were corrected for multiple comparisons using family wise error correction. Results Impaired postural knowledge was related to reduced GM volume and WM integrity. Whole brain analyses revealed effects of postural knowledge on gray matter volume within the bilateral insula extending to the IFG, the left primary motor cortex, the left superior parietal lobe and the bilateral hippocampi. Furthermore, significant correlations within fiber tracts connecting these regions – particularly alterations within the bilateral cingulum bundle and cingulum, the right superior longitudinal fasciculus, the right anterior limb of internal capsule, and the left uncinated fasciculus – were associated with PKT performance. Conclusions Poor postural knowledge in schizophrenia was associated with GM volume reductions in the praxis network. Our results are in line with the literature as particularly lesions in the left IFG were found to predict poor gesture recognition in brain damaged patients. In addition an effect of postural knowledge on WM integrity was shown within fiber tracts connecting key regions of gesture processing. Furthermore, the hippocampus is engaged in spatial memory and navigation. The results suggest that structural brain alterations in the common gesture network contribute to impaired postural knowledge in schizophrenia ( Fig. 1 ). [ABSTRACT FROM AUTHOR]

Introduction Disturbed social functioning including nonverbal communication is a core characteristic of schizophrenia. One crucial factor of nonverbal communication is gesturing. Gesturing is impaired in patients with schizophrenia. We aimed to test whether impairments in gesture performance would be present in unaffected first degree relatives of schizophrenia patients and could therefore be a potential marker of the disorder. Method We investigated 29 unaffected first degree relatives of schizophrenia patients and 29 control subjects matched for age, gender, education level, nonverbal intelligence and income. Participants performed a comprehensive test for gesture performance the Test of Upper Limb Apraxia (TULIA) ( Vanbellingen et al., 2010 ). In brief, the TULIA assesses the performance of gestures in two principal domains, i.e. imitation (production after demonstration) and pantomime (production following verbal instruction). For both domains three semantic subgroups were tested: meaningless, transitive (tool related) and intransitive (symbolic non-tool related) gestures. In addition motor behavior, working memory and frontal lobe function was assessed. Furthermore psychic experience was assessed in first degree relatives. Results First degree relatives of schizophrenia patients showed relatively severe difficulties during gesture performance. In fact, 24% of the relatives scored below the cut-off scores. In addition motor behavior was impaired in relatives. Relatives showed abnormal involuntary movements (AIMS), neurological soft signs (NSS) and abnormalities in movement (Modified Rogers Scale, MRS) as more prevalent. Moreover gesturing was predicted by impaired motor behavior in relatives. Conclusions Gesture performance impairment has been shown in unaffected first degree relatives of schizophrenia patients. Furthermore poor gesturing was associated with impaired motor behavior in first degree relatives. Our results indicate that deficits of gesturing could be linked to motor functioning. Moreover gesturing could present a potential maker of vulnerability for schizophrenia ( Table 1 ). [ABSTRACT FROM AUTHOR]

Background Schizophrenia patients are severely impaired in nonverbal communication, including gesture production and social perception. However, the impact of gestural behavior on nonverbal social perception remains unknown, as is the contribution of negative symptoms, working memory and abnormal motor behavior. The study aimed to test whether poor nonverbal social perception was related to impaired gesture performance, gestural knowledge or motor abnormalities. Methods Forty-six patients with schizophrenia (80%), schizophreniform (5%) or schizoaffective disorder (15%) and forty-four healthy controls matched for age, gender and education were included. Participants underwent comprehensive clinical and motor assessments and four tasks on nonverbal communication including gesture performance, gesture recognition, nonverbal social perception and tool use. Results Patients presented impaired nonverbal communication in all tasks compared to controls. Furthermore, in contrast to controls, performance in patients was highly correlated between tasks, not explained by supramodal cognitive deficits such as working memory. Schizophrenia patients with impaired nonverbal social perception also demonstrated poor gesture performance and knowledge. Importantly, nonverbal social perception was predicted by gesture performance, which was in turn predicted by motor abnormalities. Although negative symptom scores correlated with performance of hand gestures, they showed no association with nonverbal social perception. Conclusions The study confirmed a generalized nonverbal communication deficit in schizophrenia. Specifically, the findings suggested that the gestural impairment has a relevant impact on nonverbal social perception in schizophrenia, which is independent of negative symptoms or impaired working memory. [ABSTRACT FROM AUTHOR]