Reduced syntactic recursion in spontaneous speech of Parkinson's disease patients.

Although characterized as a movement disorder, Parkinson's disease (PD) affects more than just the motor system. Within the heterogenous non-motor symptoms, language impairment is frequent but poorly understood beyond semantic processing. This study investigates the impact of PD on syntactic subordination in spontaneous language production. Fifteen PD patients in ON levodopa status narrated a short story guided by a set of pictures. Thirteen PD patients were also assessed in OFF levodopa status. Narrations were digitally recorded, subsequently transcribed and annotated, making the produced speech accessible to systematical quantitative analysis. Compared to a healthy matched control group, PD patients showed a significant reduction of subordinating structures while the number of non-embedding sentences remained unaffected. No significant effect comparing ON versus OFF levodopa status emerged. Our results suggest a contribution of the basal ganglia to language processing, such as syntactic composition, which, however, does not seem to be dopamine dependent.

Altered performance monitoring in Tourette Syndrome: an MEG investigation.

The error-related negativity (ERN) is an event-related potential component indexing processes of performance monitoring during simple stimulus-response tasks: the ERN is typically enhanced for error processing and conflicting response representations. Investigations in healthy participants and different patient groups have linked the ERN to the dopamine system and to prefrontal information processing. As in patients with Tourette Syndrome (TS) both dopamine release and prefrontal information processing are impaired, we hypothesized that performance monitoring would be altered, which was investigated with magnetencephalography (MEG). We examined performance monitoring in TS patients by assessing the magnetic equivalent of the ERN (mERN). The mERN was investigated in tic-free trials of eight adult, unmedicated TS patients without clinically significant comorbidity and ten matched healthy controls while performing a Go/NoGo task in selected frontocentral channels. The analysis of the response-related amplitudes of the event-related magnetic field showed that TS patients, in contrast to controls, did not show earlier amplitude modulation (between 70 and 105 ms after response onset) depending on response type (errors or correct responses). In both groups significant mERN amplitudes in the time-window between 105 and 160 ms after response onset were detected thus pointing at only later error processing in TS patients. In TS patients, early error-related processing might be affected by an enhanced motor control triggered by a conflict between the targeted high task performance and tic suppression. TS patients seem to tend to initially process all responses as erroneous responses.

Induced and Evoked Brain Activation Related to the Processing of Onomatopoetic Verbs.

Grounded cognition theory postulates that cognitive processes related to motor or sensory content are processed by brain networks involved in motor execution and perception, respectively. Processing words with auditory features was shown to activate the auditory cortex. Our study aimed at determining whether onomatopoetic verbs (e.g., "tröpfeln"-to dripple), whose articulation reproduces the sound of respective actions, engage the auditory cortex more than non-onomatopoetic verbs. Alpha and beta brain frequencies as well as evoked-related fields (ERFs) were targeted as potential neurophysiological correlates of this linguistic auditory quality. Twenty participants were measured with magnetoencephalography (MEG) while semantically processing visually presented onomatopoetic and non-onomatopoetic German verbs. While a descriptively stronger left temporal alpha desynchronization for onomatopoetic verbs did not reach statistical significance, a larger ERF for onomatopoetic verbs emerged at about 240 ms in the centro-parietal area. Findings suggest increased cortical activation related to onomatopoeias in linguistically relevant areas.

Neurophysiological mechanisms of perspective-taking: An MEG investigation of agency.

According to the embodied cognition framework, sensory and motor areas are recruited during language understanding through simulation processes. Behavioral and imaging findings point to a dependence of the latter on perspective-taking (e.g., first person "I" versus third person "s/he"). The current study aims at identifying possible neurophysiological correlates of perspective in a linguistic context. Twenty healthy participants were measured with magnetoencephalography (MEG) while semantically processing visually presented inflected German verbs in the first- and third-person perspective, simple present tense. Results show that the first-person perspective induces stronger beta (15-25 Hz) desynchronization in the right-hemispheric posterior superior temporal sulcus, ventral posterior cingulate gyrus, and V5/MT+ area; no modulation of sensorimotor cortex emerged. Moreover, a stronger event-related field (ERF) was observed for the first-person perspective at about 150 ms after pronoun-verb onset, originating in occipital and moving to central and left temporal cortical sites. No effect of perspective on sensory gating was found when targeting the N1 component related to tones following the linguistic stimuli. Results indicate an effect of linguistic perspective-taking on brain activation patterns. The contribution of the single brain areas and their role in self-other distinction is further discussed.

Auditory cortex sensitivity to the loudness attribute of verbs.

The auditory cortex was shown to be activated during the processing of words describing actions with acoustic features. The present study further examines whether processing visually presented action words characterized by different levels of loudness, i.e. "loud" (to shout) and "quiet" actions (to whisper), differentially engage the auditory cortex. Twenty healthy participants were measured with magnetoencephalography (MEG) while reading inflected verbs followed by a short tone and semantic tasks. Based on the results of a localizer task, loudness sensitive temporal Brodmann areas A22, A41/42, and pSTS were inspected in the word paradigm. "Loud" actions induced significantly stronger beta power suppression compared to "quiet" actions in the left hemisphere. Smaller N100m amplitude related to tones following "loud" compared to "quiet" actions confirmed that auditory cortex sensitivity was modulated by action words. Results point to possible selective auditory simulation mechanisms involved in verb processing and support embodiment theories.

Action verb processing specifically modulates motor behaviour and sensorimotor neuronal oscillations.

Understanding action-related language recruits the brain's motor system and can interact with motor behaviour. The current study shows MEG oscillatory patterns during verb-motor priming. Hand and foot verbs were followed by hand or foot responses, with faster reaction times for congruent conditions. In ROIs placed in the hand/arm and foot/leg portions of the sensorimotor cortex, this behavioural priming effect was accompanied by modulations in MEG oscillatory patterns preceding the responses. Power suppression in the alpha/beta frequency bands was reduced in congruent conditions in the body-part-specific ROIs. These results imply that the verb-motor priming effect may be a direct consequence of motor cortex contributions to action word processing.

A peek into premonitory urges in Tourette syndrome: Temporal evolution of neurophysiological oscillatory signatures.

BACKGROUND: Tics are the core symptom of patients with Gilles de la Tourette syndrome, yet the spatial-temporal dynamics of neural activity causing a tic remains to be determined. OBJECTIVE: Identification of cortical events preceding tic onset. METHODS: In twelve patients with Tourette syndrome we performed magnetoencephalography to trace the time course of beta oscillations (15-30 Hz) in motor cortical areas before tic onset. RESULTS: Patients showed a biphasic modulation of cortical beta activity during the second before tic onset. We observed an initial increase of beta power over the left-hemispheric channels overlying the motor cortex. This increase was subsequently replaced by a decrease in beta power. The beta decrease close to tic onset resembled the typical pattern accompanying preparation of voluntary movements. Only the initial increase in beta power positively correlated with the intensity of motor urges preceding tics. CONCLUSIONS: The spatial-temporal dynamics of cortical activity suggests a voluntary component of tics that might be triggered by a failure of compensatory motor inhibitory mechanisms.

Electrophysiological correlates of concept type shifts.

A recent semantic theory of nominal concepts by Löbner [1] posits that-due to their inherent uniqueness and relationality properties-noun concepts can be classified into four concept types (CTs): sortal, individual, relational, functional. For sortal nouns the default determination is indefinite (a stone), for individual nouns it is definite (the sun), for relational and functional nouns it is possessive (his ear, his father). Incongruent determination leads to a concept type shift: his father (functional concept: unique, relational)-a father (sortal concept: non-unique, non-relational). Behavioral studies on CT shifts have demonstrated a CT congruence effect, with congruent determiners triggering faster lexical decision times on the subsequent noun than incongruent ones [2, 3]. The present ERP study investigated electrophysiological correlates of congruent and incongruent determination in German noun phrases, and specifically, whether the CT congruence effect could be indexed by such classic ERP components as N400, LAN or P600. If incongruent determination affects the lexical retrieval or semantic integration of the noun, it should be reflected in the amplitude of the N400 component. If, however, CT congruence is processed by the same neuronal mechanisms that underlie morphosyntactic processing, incongruent determination should trigger LAN or/and P600. These predictions were tested in two ERP studies. In Experiment 1, participants just listened to noun phrases. In Experiment 2, they performed a wellformedness judgment task. The processing of (in)congruent CTs (his sun vs. the sun) was compared to the processing of morphosyntactic and semantic violations in control conditions. Whereas the control conditions elicited classic electrophysiological violation responses (N400, LAN, & P600), CT-incongruences did not. Instead they showed novel concept-type specific response patterns. The absence of the classic ERP components suggests that CT-incongruent determination is not perceived as a violation of the semantic or morphosyntactic structure of the noun phrase.

Semantic discrimination impacts tDCS modulation of verb processing.

Motor cortex activation observed during body-related verb processing hints at simulation accompanying linguistic understanding. By exploiting the up- and down-regulation that anodal and cathodal transcranial direct current stimulation (tDCS) exert on motor cortical excitability, we aimed at further characterizing the functional contribution of the motor system to linguistic processing. In a double-blind sham-controlled within-subjects design, online stimulation was applied to the left hemispheric hand-related motor cortex of 20 healthy subjects. A dual, double-dissociation task required participants to semantically discriminate concrete (hand/foot) from abstract verb primes as well as to respond with the hand or with the foot to verb-unrelated geometric targets. Analyses were conducted with linear mixed models. Semantic priming was confirmed by faster and more accurate reactions when the response effector was congruent with the verb's body part. Cathodal stimulation induced faster responses for hand verb primes thus indicating a somatotopical distribution of cortical activation as induced by body-related verbs. Importantly, this effect depended on performance in semantic discrimination. The current results point to verb processing being selectively modifiable by neuromodulation and at the same time to a dependence of tDCS effects on enhanced simulation. We discuss putative mechanisms operating in this reciprocal dependence of neuromodulation and motor resonance.

Body-part specific interactions of action verb processing with motor behaviour.

The interaction of action-related language processing with actual movement is an indicator of the functional role of motor cortical involvement in language understanding. This paper describes two experiments using single action verb stimuli. Motor responses were performed with the hand or the foot. To test the double dissociation of language-motor facilitation effects within subjects, Experiments 1 and 2 used a priming procedure where both hand and foot reactions had to be performed in response to different geometrical shapes, which were preceded by action verbs. In Experiment 1, the semantics of the verbs could be ignored whereas Experiment 2 included semantic decisions. Only Experiment 2 revealed a clear double dissociation in reaction times: reactions were facilitated when preceded by verbs describing actions with the matching effector. In Experiment 1, by contrast, there was an interaction between verb-response congruence and a semantic variable related to motor features of the verbs. Thus, the double dissociation paradigm of semantic motor priming was effective, corroborating the role of the motor system in action-related language processing. Importantly, this effect was body part specific.

Correction: Grasping Hand Verbs: Oscillatory Beta and Alpha Correlates of Action-Word Processing.

[This corrects the article DOI: 10.1371/journal.pone.0108059.].

Auditory perception modulated by word reading.

Theories of embodied cognition positing that sensorimotor areas are indispensable during language comprehension are supported by neuroimaging and behavioural studies. Among others, the auditory system has been suggested to be important for understanding sound-related words (visually presented) and the motor system for action-related words. In this behavioural study, using a sound detection task embedded in a lexical decision task, we show that in participants with high lexical decision performance sound verbs improve auditory perception. The amount of modulation was correlated with lexical decision performance. Our study provides convergent behavioural evidence of auditory cortex involvement in word processing, supporting the view of embodied language comprehension concerning the auditory domain.

Increased beta rhythm as an indicator of inhibitory mechanisms in tourette syndrome.

BACKGROUND: Inhibitory oscillatory mechanisms subserving tic compensation have been put forward in Tourette syndrome. Modulation of the beta rhythm (15-25 Hz) as the well-established oscillatory movement execution-inhibition indicator was tested during a cognitive-motor task in patients with Tourette syndrome. METHODS: Performing a Go/NoGo task, 12 patients with Tourette syndrome and 12 matched controls were recorded using whole-head magnetoencephalography. RESULTS: Compared to healthy participants, patients showed less beta suppression in the sensorimotor area and enhanced beta power in parieto-occipital brain regions contralaterally to the response hand. Average beta power and power gain correlated negatively with tic severity. CONCLUSIONS: Increased motor inhibitory as well as visuomotor attentional processes are likely to subserve tic compensation. Correlational results suggest that stronger inhibitory compensation accompanies less tic severity.

Language-motor interference reflected in MEG beta oscillations.

The involvement of the brain's motor system in action-related language processing can lead to overt interference with simultaneous action execution. The aim of the current study was to find evidence for this behavioural interference effect and to investigate its neurophysiological correlates using oscillatory MEG analysis. Subjects performed a semantic decision task on single action verbs, describing actions executed with the hands or the feet, and abstract verbs. Right hand button press responses were given for concrete verbs only. Therefore, longer response latencies for hand compared to foot verbs should reflect interference. We found interference effects to depend on verb imageability: overall response latencies for hand verbs did not differ significantly from foot verbs. However, imageability interacted with effector: while response latencies to hand and foot verbs with low imageability were equally fast, those for highly imageable hand verbs were longer than for highly imageable foot verbs. The difference is reflected in motor-related MEG beta band power suppression, which was weaker for highly imageable hand verbs compared with highly imageable foot verbs. This provides a putative neuronal mechanism for language-motor interference where the involvement of cortical hand motor areas in hand verb processing interacts with the typical beta suppression seen before movements. We found that the facilitatory effect of higher imageability on action verb processing time is perturbed when verb and motor response relate to the same body part. Importantly, this effect is accompanied by neurophysiological effects in beta band oscillations. The attenuated power suppression around the time of movement, reflecting decreased cortical excitability, seems to result from motor simulation during action-related language processing. This is in line with embodied cognition theories.

Grasping hand verbs: oscillatory beta and alpha correlates of action-word processing.

The grounded cognition framework proposes that sensorimotor brain areas, which are typically involved in perception and action, also play a role in linguistic processing. We assessed oscillatory modulation during visual presentation of single verbs and localized cortical motor regions by means of isometric contraction of hand and foot muscles. Analogously to oscillatory activation patterns accompanying voluntary movements, we expected a somatotopically distributed suppression of beta and alpha frequencies in the motor cortex during processing of body-related action verbs. Magnetoencephalographic data were collected during presentation of verbs that express actions performed using the hands (H) or feet (F). Verbs denoting no bodily movement (N) were used as a control. Between 150 and 500 msec after visual word onset, beta rhythms were suppressed in H and F in comparison with N in the left hemisphere. Similarly, alpha oscillations showed left-lateralized power suppression in the H-N contrast, although at a later stage. The cortical oscillatory activity that typically occurs during voluntary movements is therefore found to somatotopically accompany the processing of body-related verbs. The combination of a localizer task with the oscillatory investigation applied to verb reading as in the present study provides further methodological possibilities of tracking language processing in the brain.

Neuromagnetic hand and foot motor sources recruited during action verb processing.

The current study investigated sensorimotor involvement in the processing of verbs describing actions performed with the hands, feet, or no body part. Actual movements were used to identify neuromagnetic sources for hand and foot actions. These sources constrained the analysis of verb processing. While hand and foot sources picked up activation in all three verb conditions, peak amplitudes showed an interaction of source and verb condition at 200 ms after word onset, thereby reflecting effector-specificity. Specifically, hand verbs elicited significantly higher peak amplitudes than foot verbs in hand sources. Our results are in line with theories of embodied cognition that assume an involvement of sensorimotor areas in early stages of lexico-semantic processing, even for single words without a semantic or motor task.

Altered intrahemispheric structural connectivity in Gilles de la Tourette syndrome.

Gilles de la Tourette syndrome (GTS) is a common developmental neuropsychiatric disorder characterized by tics and frequent psychiatric comorbidities, often causing significant disability. Tic generation has been linked to disturbed networks of brain areas involved in planning, controlling and execution of actions, particularly structural and functional disorders in the striatum and cortico-striato-thalamo-cortical loops. We therefore applied structural diffusion tensor imaging (DTI) to characterize changes in intrahemispheric white matter connectivity in cortico-subcortical circuits engaged in motor control in 15 GTS patients without psychiatric comorbidities. White matter connectivity was analyzed by probabilistic fiber tractography between 12 predefined cortical and subcortical regions of interest. Connectivity values were combined with measures of clinical severity rated by the Yale Global Tic Severity Scale (YGTSS). GTS patients showed widespread structural connectivity deficits. Lower connectivity values were found specifically in tracts connecting the supplementary motor areas (SMA) with basal ganglia (pre-SMA-putamen, SMA-putamen) and in frontal cortico-cortical circuits. There was an overall trend towards negative correlations between structural connectivity in these tracts and YGTSS scores. Structural connectivity of frontal brain networks involved in planning, controlling and executing actions is reduced in adult GTS patients which is associated with tic severity. These findings are in line with the concept of GTS as a neurodevelopmental disorder of brain immaturity.

Costs of control: decreased motor cortex engagement during a Go/NoGo task in Tourette's syndrome.

Gilles de la Tourette syndrome is a neuropsychiatric disorder characterized by an impaired ability to inhibit unwanted behaviour. Although the presence of chronic motor and vocal tics defines Tourette's syndrome, other distinctive behavioural features like echo- and coprophenomena, and non-obscene socially inappropriate behaviour are also core features. We investigated neuronal activation during stimulus-driven execution and inhibition of prepared movements in Tourette's syndrome. To this end, we performed event-related functional magnetic resonance imaging and structural diffusion tensor imaging in 15 moderately affected uncomplicated patients with 'pure' Tourette's syndrome and 15 healthy control participants matched for age and gender. Subjects underwent functional magnetic resonance imaging during a Go/NoGo reaction time task. They had to withhold a prepared finger movement for a variable time until a stimulus instructed them to either execute (Go) or inhibit it (NoGo). Tics were monitored throughout the experiments, combining surface electromyogram, video recording, and clinical assessment in the scanner. Patients with Tourette's syndrome had longer reaction times than healthy controls in Go trials and made more errors in total. Their functional brain activation was decreased in left primary motor cortex and secondary motor areas during movement execution (Go trials) but not during response inhibition (NoGo trials) compared with healthy control subjects. Volume of interest analysis demonstrated less task-related activation in patients with Tourette's syndrome in primary and secondary motor cortex bilaterally, but not in the basal ganglia and cortical non-motor areas. They showed reduced co-activation between the left primary sensory-motor hand area and a network of contralateral sensory-motor areas and ipsilateral cerebellar regions. There were no between-group differences in structural connectivity of the left primary sensory-motor cortex as measured by diffusion tensor imaging-based probabilistic tractography. Our results link reduced sensory-motor cortical activation during movement execution to a decreased co-activation between the sensory-motor cortex and other brain areas involved in motor processing. These functional changes in patients with Tourette's syndrome might result from adaptive reorganization in fronto-parietal brain networks engaged in motor and behavioural control, possibly triggered by abnormal processing and presumably overactivity in cortico-striato-cortical circuits. This might enable patients with Tourette's syndrome to better suppress unwanted movements but comes at a price of behavioural deficits in other domains.

Increased sensory feedback in Tourette syndrome.

Tourette syndrome (TS) is a neuro-psychiatric disorder being characterized by motor and phonic tics typically preceded by sensory urges. Given the latter the role of the sensory system and sensorimotor interaction in TS has recently gained increased attention. 12 TS patients and 12 matched control subjects performed two tasks, requiring simple finger movements: a Go/NoGo task and a self paced movement task. Neurophysiological data was recorded using magnetoencephalography (MEG). Event related responses around movement onset, i.e. motor field (MF) occurring directly prior to the movement and movement evoked field (MEF) immediately after movement onset were analyzed using dipole modeling. MF peak amplitudes did not differ between groups in either task. In contrast, in both tasks MEF peak amplitudes were increased in TS patients. Moreover, larger MEF amplitudes during self paced movements were inversely correlated with motor tic frequency and severity. Enlarged MEF amplitudes as a marker of early sensory feedback of one's own movements probably represent enlarged sensory input from the periphery resulting from altered subcortical gating. We conclude that TS patients exhibit altered sensory-motor processing involved in voluntary movement control, which might also be successful in tic control.

Echoes from childhood--imitation in Gilles de la Tourette Syndrome.

BACKGROUND: Tourette syndrome patients are reported to show automatic imitation (echopraxia), but this has not yet been proven experimentally. METHODS: Video clips showing either tics of other Tourette patients or spontaneous movements of healthy subjects were presented to Tourette patients and healthy subjects. Participants' responses were assessed using blinded review of video recordings by 2 independent raters and related to stimuli presented. RESULTS: Both raters detected more echoes in patients. In a permutation analysis, no healthy subject had echoes above chance level. In contrast, 6 and 5 patients were classified as echoers according to rater 1 and rater 2, respectively, in 1 analysis, and 9 patients were so classified in a second analysis (according to rater 2 only). Concordance between raters was high. Patients echoed both following stimuli showing tics and following stimuli showing spontaneous movements. Most echoes were part of patients' individual tic repertoire. CONCLUSIONS: Echopraxia is a hallmark of Tourette syndrome.