Slips of the tongue in patients with Gilles de la Tourette syndrome

BACKGROUND

Motor and vocal tics are the main symptom of Gilles de la Tourette-syndrome (GTS). A particular complex vocal tic comprises the utterance of swear words, termed coprolalia. Since taboo words are socially inappropriate, they are normally suppressed by people, which implies cognitive control processes.

METHOD

To investigate the control of the unintentional pronunciation of taboo words and the associated processes of conflict monitoring, we used the "Spoonerisms of Laboratory Induced Predisposition" (SLIP) paradigm. Participants read multiple inductor word pairs with the same phonemes, followed by pronouncing a target pair with inverse phonemes. This led to a conflict between two competing speech plans: the correct word pair and the word pair with inverted phonemes. Latter speech error, a spoonerism, could result in a neutral or taboo word. We investigated 19 patients with GTS and 23 typically developed controls (TDC) and measured participants' electroencephalography (EEG) during the SLIP task.

RESULTS

At the behavioral level less taboo than neutral word spoonerisms occurred in both groups without significant differences. Event-related brain potentials (ERP) revealed a difference between taboo and neutral word conditions in the GTS group at the midline electrodes in a time range of 250-400 ms after the speech prompt, which was not found in the TDC group. The extent of this effect depended on the number of inductor word pairs, suggesting an increasing level of cognitive control in the GTS group.

CONCLUSION

The differences between taboo and neutral word conditions in patients with GTS compared to TDC suggest an altered recruitment of cognitive control processes in GTS, likely enlisted to suppress taboo words.

Tracking the habituation of the event-related EEG potential in automatic change detection using an auditory two-tone oddball paradigm

The mismatch negativity and the P3a of the event-related EEG potential reflect the electrocortical response to a deviant stimulus in a series of stimuli. Although both components have been investigated in various paradigms, these paradigms usually incorporate many repetitions of the same deviant, thus leaving open whether both components vary as a function of the deviant's position in a series of deviant stimuli-i.e. whether they are subject to qualitative/quantitative habituation from one instantiation of a deviant to the next. This is so because the detection of mismatch negativity/P3a in the event-related EEG potential requires an averaging over dozens or hundreds of stimuli, i.e. over many instantiations of the deviant per participant. The present study addresses this research gap. We used a two-tone oddball paradigm implementing only a small number of (deviant) stimuli per participant, but applying it to a large number of participants (n > 230). Our data show that the mismatch negativity amplitude exhibits no decrease as a function of the deviant's position in a series of (standard and) deviant stimuli. Importantly, only after the very first deviant stimulus, a distinct P3a could be detected, indicative of an orienting reaction and an attention shift, and thus documenting a dissociation of mismatch negativity and P3a.

Changes in brain structure in subjects with resistance to thyroid hormone due to THRB mutations

BACKGROUND

Being critical for brain development and neurocognitive function thyroid hormones may have an effect on behaviour and brain structure. Our exploratory study aimed to delineate the influence of mutations in the thyroid hormone receptor (TR) ß gene on brain structure.

METHODS

High-resolution 3D T1-weighted images were acquired in 21 patients with a resistance to thyroid hormone ß (RTHß) in comparison to 21 healthy matched-controls. Changes in grey and white matter, as well as cortical thickness were evaluated using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI).

RESULTS

RTHß patients showed elevated circulating fT4 & fT3 with normal TSH concentrations, whereas controls showed normal thyroid hormone levels. RTHß patients revealed significantly higher scores in a self-rating questionnaire for attention deficit hyperactivity disorder (ADHD). Imaging revealed alterations of the corticospinal tract, increased cortical thickness in bilateral superior parietal cortex and decreased grey matter volume in bilateral inferior temporal cortex and thalamus.

CONCLUSION

RTHb patients exhibited structural changes in multiple brain areas. Whether these structural changes are causally linked to the abnormal behavioral profile of RTHß which is similar to ADHD, remains to be determined.

Differences in Implicit Attitudes in West and East Germans as Measured by the Go/NoGo Association Task and Event-related EEG Potentials

BACKGROUND AND OBJECTIVE

Implicit social cognition refers to attitudes and stereotypes that may reside outside conscious awareness and control but that still affect human behavior. In particular, the implicit favoritism of an ingroup, to which an individual belongs, as opposed to an outgroup, to which the individual does not belong, characterized as ingroup bias, is of interest and is investigated here.

METHOD

We used a Go/NoGo association task (GNAT) and behavioral and electroencephalographic (event-related EEG potential [ERP] analysis) measures to investigate the implicit bias toward cities in East Germany, West Germany, and Europe, in 16 individuals each from West and East Germany (mixed gender, M age = 24). The GNAT assesses an individual's Go and NoGo responses for a given association between a target category and either pole (positive or negative) of an evaluative dimension.

RESULTS

Behavioral measures revealed slightly faster reaction times to the combination of European city names and negative, as compared with positive, evaluative words in both groups. ERP analysis showed an increased negativity at 400-800 ms poststimulus in the incongruent conditions of East German city/positive word pairings (in West Germans) and West German city/positive word pairings (in East Germans).

CONCLUSION

An implicitly moderately negative evaluation of Europe by both groups was exhibited based on the behavioral data, and an increased level of conflict arising from the "incongruent" pairings (ie, as manifestation of an implicitly negative attitude toward East Germany in West Germans, and toward West Germany in East Germans) was exhibited based on the electrophysiological data.

Anti-flotillin-1/2 antibodies in a patient with neurogenic muscle atrophy and mild neuropsychological impairment

Autoimmune-mediated neural inflammation can affect both the central and the peripheral nervous system. Recently, antibodies against the peripheral membrane protein flotillin have been described in patients with multiple sclerosis, limbic encephalitis and sensorimotor demyelinating polyneuropathy. Here, we report the case of a 75-year-old male patient presenting with slowly progressive muscle weakness, as well as mild cognitive impairment. MR neurography of the leg showed fascicular enlargement and inflammation of ischiadic nerve fibers, while cerebral MRI showed bilateral hippocampal atrophy. Serological testing revealed positive anti-flotillin-1/2 antibodies in serum (1:100) and CSF (1:1). Assuming autoimmune anti-flotillin antibody-associated neurogenic muscle atrophy, the patient was treated with immunoglobulins, which led to a clinical improvement of muscle weakness. In light of the positive anti-flotillin antibodies and the local CNS immunoglobulin production, the mild cognitive impairment and hippocampal atrophy were interpreted as a cerebral involvement in the sense of a subclinical limbic encephalitis. We conclude that anti-flotillin antibodies can be associated with central and peripheral nervous system autoimmunity and should be considered in diagnostical workup.

Studying Implicit Attitudes Towards Smoking: Event-Related Potentials in the Go/NoGo Association Task

Cigarette smoking and other addictive behaviors are among the main preventable risk factors for several severe and potentially fatal diseases. It has been argued that addictive behavior is controlled by an automatic-implicit cognitive system and by a reflective-explicit cognitive system, that operate in parallel to jointly drive human behavior. The present study addresses the formation of implicit attitudes towards smoking in both smokers and non-smokers, using a Go/NoGo association task (GNAT), and behavioral and electroencephalographic (EEG) measures. The GNAT assesses, via quantifying participants’ reaction times, the strength of association between a target category and either pole of an evaluative dimension (positive or negative). EEG analysis is performed to determine the temporal course of the event-related potential (ERP) components underlying Go/NoGo decisions and implicit attitude formation. Both smokers and non-smokers showed prolonged reaction times to smoking-related pictures when the pictures were coupled with positive evaluative words (“incongruent condition”). This indicates negative implicit attitudes towards smoking in both groups alike at the time point of the behavioral response (600–700 ms post-stimulus). However, only the non-smokers, not the smokers, were found to show a delay of the N200 component in the incongruent condition. This is interpreted as reflecting ambivalent or even positive implicit attitudes towards smoking in the smoker group at the time point of the N200 (300–400 ms post-stimulus). Our study thus provides evidence for the hypothesis that implicit attitudes are subject to changes within several hundred milliseconds after stimulus presentation, and can be altered in the course of their formation.

The Suppression of Taboo Word Spoonerisms Is Associated With Altered Medial Frontal Negativity: An ERP Study

The constant internal monitoring of speech is a crucial feature to ensure the fairly error-free process of speech production. It has been argued that internal speech monitoring takes place through detection of conflict between different response options or “speech plans.” Speech errors are thought to occur because two (or more) competing speech plans become activated, and the speaker is unable to inhibit the erroneous plan(s) prior to vocalization. A prime example for a speech plan that has to be suppressed is the involuntary utterance of a taboo word. The present study seeks to examine the suppression of involuntary taboo word utterances. We used the “Spoonerisms of Laboratory Induced Predisposition” (SLIP) paradigm to elicit two competing speech plans, one being correct and one embodying either a taboo word or a non-taboo word spoonerism. Behavioral data showed that inadequate speech plans generally were effectively suppressed, although more effectively in the taboo word spoonerism condition. Event-related potential (ERP) analysis revealed a broad medial frontal negativity (MFN) after the target word pair presentation, interpreted as reflecting conflict detection and resolution to suppress the inadequate speech plan. The MFN was found to be more pronounced in the taboo word spoonerism compared to the neutral word spoonerism condition, indicative of a higher level of conflict when subjects suppressed the involuntary utterance of taboo words.

The Electrocortical Signature of Successful and Unsuccessful Deception in a Face-to-Face Social Interaction

Deceptive behavior, and the evaluation of others' behavior as truthful or deceptive, are crucial aspects of human social interaction. We report a study investigating two participants in a social interaction, performing a deception task. The first participant, the "informant," made true or false autobiographical statements. The second participant, the "detective," then classified these statements as truth or lie. Behavioral data showed that detectives performed slightly above chance and were better at correctly identifying true as compared with deceptive statements. This presumably reflects the "truth bias": the finding that individuals are more likely to classify others' statements as truthful than as deceptive - even when informed that a lie is as likely to be told as the truth. Electroencephalography (EEG) was recorded from the informant. Event-related potential (ERP) analysis revealed a smaller contingent negative variation (CNV) preceding "convincing" statements (statements classified as true by the detective) compared to "unconvincing" statements (statements classified as lie by the detective) - irrespective of whether the statements were actually truthful or deceptive. This finding suggests a distinct electrocortical signature of "successful" compared to "unsuccessful" deceptive statements. One possible explanation is that the pronounced CNV indicates the individuals' higher "cognitive load" when processing unconvincing statements.

Swearing, Cursing, Coprophenomena

Abstract. In healthy individuals, expletive language occurs as swearing/cursing, in patients with Tourette syndrome as coprolalia. Swearing and coprolalia thus have been likened as two ends of a continuum. Both occur apparently automatically, are triggered by emotional activation, e. g., by stress or pain, and are typically instantiations of nonpropositional language. Neurobiologically, a thalamo-cortical-limbic dysfunction is discussed. However, there are notable differences between the two: While swearing fulfills intra- and inter-individual functions coprolalia seems less functional and can result in considerable social stigma because of their occurrence in socially inappropriate situations. Patients with coprolalia report antecedents, especially feelings of urge and premonitory sensations, like itches or tingles. Finally, coprolalia seems to extend to more serious and insulting expressions compared to “everyday” swearwords.

Axonal projection-specific differences in somatodendritic α2 autoreceptor function in locus coeruleus neurons

The locus coeruleus (LC) contains the majority of central noradrenergic neurons sending wide projections throughout the entire CNS. The LC is considered to be essential for multiple key brain functions including arousal, attention and adaptive stress responses as well as higher cognitive functions and memory. Electrophysiological studies of LC neurons have identified several characteristic functional features such as low-frequency pacemaker activity with broad action potentials, transient high-frequency burst discharges in response to salient stimuli and an apparently homogeneous inhibition of firing by activation of somatodendritic α2 autoreceptors (α2AR). While stress-mediated plasticity of the α2AR response has been described, it is currently unclear whether different LC neurons projecting to distinct axonal targets display differences in α2AR function. Using fluorescent beads-mediated retrograde tracing in adult C57Bl6/N mice, we compared the anatomical distributions and functional in vitro properties of identified LC neurons projecting either to medial prefrontal cortex, hippocampus or cerebellum. The functional in vitro analysis of LC neurons confirmed their mostly uniform functional properties regarding action potential generation and pacemaker firing. However, we identified significant differences in tonic and evoked α2AR-mediated responses. While hippocampal-projecting LC neurons were partially inhibited by endogenous levels of norepinephrine and almost completely silenced by application of saturating concentrations of the α2 agonist clonidine, prefrontal-projecting LC neurons were not affected by endogenous levels of norepinephrine and only partially inhibited by saturating concentrations of clonidine. Thus, we identified a limited α2AR control of electrical activity for prefrontal-projecting LC neurons indicative of functional heterogeneity in the LC-noradrenergic system.

Permanent lesion to the corticospinal tract after therapy with capecitabine

Capecitabine is an oral fluoropyrimidine used to treat solid tumours such as colorectal and breast cancer. A rare but severe side effect is capecitabine-induced leukoencephalopathy, including bilateral lesion to the corticospinal tract. However, neurological symptoms due to capecitabine treatment are usually reported to be reversible after discontinuation of capecitabine. Here, we present the case of a patient with bilateral degeneration of the corticospinal tract and progressive spastic tetraplegia after chemotherapy with capecitabine mimicking primary lateral sclerosis. Although therapy with capecitabine was ended, symptoms substantially worsened over the following years and the patient finally died from aspiration pneumonia almost 3 years after the application of capecitabine.

Anti-Amphiphysin-associated limbic encephalitis in a 72-year-old patient with aortic angiosarcoma

Paraneoplastic autoimmune encephalopathic syndromes have been described most often in association with small cell lung cancer or breast cancer, tumours of the ovaries, testes, lymphoma and thymoma. Antibodies associated with paraneoplastic encephalopathies are, among others, anti-Hu, anti-Ma2 and, in part, anti-N-methyl-D-aspartate(NMDA)-receptor antibodies. Here, we present the case of a 72-year-old patient hospitalised due to progressive cognitive decline and disorientation. Diagnostic workup revealed paraneoplastic anti-amphiphysin associated limbic encephalitis on the basis of an aortic angiosarcoma with metastases to kidney, muscle and bones. Highly aggressive chemotherapy as well as immunosuppressive therapy and cytoreductive laparoscopic nephrectomy were initiated. However, follow-up revealed further tumour progress and a worsening of neurological symptoms.