The human globus pallidus internus is sensitive to rewards - Evidence from intracerebral recordings.

Background: The globus pallidus internus (GPi) is the final output relay of the basal ganglia for the control of movements but has also been shown to belong to a second pathway projecting to the lateral habenula. This latter pathway is related to reward processing.

Method: This prompted us to record, in eight patients receiving deep brain stimulation of the GPi for the alleviation of various movement disorders, local field potentials (LFP) while these patients performed a lottery task.

The mental number line electrified: brain potentials in a numerical flanker task.

It has been suggested that the mental representation of numbers is spatial in nature such that numbers are ordered on a mental number line. In the present investigation we use a variant of the Eriksen flanker task requiring a magnitude decision (smaller or larger than 5) for a central target number by pressing a response button with the right or left hand. The target number is flanked by irrelevant distracters that are either identical to the target, different from the target but biasing the same response, or different from the target and biasing a different response.

Human hypothalamus shows differential responses to basic motivational stimuli--an invasive electrophysiology study.

The hypothalamus supports basic motivational behaviours such as mating and feeding. Recording directly from the posterior inferior hypothalamus in a male patient receiving a deep brain stimulation (DBS) electrode for the alleviation of cluster headache, we tested the hypothalamic response to different classes of motivational stimuli (sexually relevant: pictures of dressed and undressed women; pictures of food) and pictures of common objects as control. Averaged local field potentials (LFP) to sexually relevant stimuli were characterized by a biphasic significantly enhanced response (relative to objects; bootstrapping statistics) with a first phase starting at around 200 ms and a second phase peaking at around 600 ms.

Neurophysiological markers of novelty processing are modulated by COMT and DRD4 genotypes.

Humans are faced with the dilemma to maintain a stable cognitive set on the one hand and to be able to redirect and switch attention to novel stimuli of potential importance. The dopaminergic system has been implicated in the balance between these two antagonistic constraints and in particular in novelty processing. Here we studied the impact of two polymorphisms affecting dopaminergic functioning (COMT Val108/158Met and DRD4 SNP -521) on neurophysiological correlates of novelty processing.

The effects of COMT (Val108/158Met) and DRD4 (SNP -521) dopamine genotypes on brain activations related to valence and magnitude of rewards.

People's sensitivity to reinforcing stimuli such as monetary gains and losses shows a wide interindividual variation that might in part be determined by genetic differences. Because of the established role of the dopaminergic system in the neural encoding of rewards and negative events, we investigated young healthy volunteers being homozygous for either the Valine or Methionine variant of the catechol-O-methyltransferase (COMT) codon 158 polymorphism as well as homozygous for the C or T variant of the SNP -521 polymorphism of the dopamine D4 receptor. Participants took part in a gambling paradigm featuring unexpectedly high monetary gains and losses in addition to standard gains/losses of expected magnitude while undergoing functional magnetic resonance imaging at 3 T.

Genetic variability in the dopamine system (dopamine receptor D4, catechol-O-methyltransferase) modulates neurophysiological responses to gains and losses.

Background: Interindividual variability in the processing of reward might be partially explained by genetic differences in the dopamine system. Here, we study whether brain responses (event-related potentials [ERPs], oscillatory activity) to monetary gains and losses in normal human subjects are modulated as a function of two dopaminergic polymorphisms (catechol-O-methyltransferase [COMT] valine [Val]158methionine [Met], dopamine receptor D4 [DRD4] single nucleotide polymorphism [SNP] -521).

Methods: Forty participants homozygous for the different alleles of both polymorphisms were selected from a larger population to assess the main effects and interactions.

Attention to human speakers in a virtual auditory environment: brain potential evidence.

Listening to a speech message requires the accurate selection of the relevant auditory input especially when distracting background noise or other speech messages are present. To investigate such auditory selection processes we presented three different speech messages simultaneously spoken by different actors at separate spatial locations (-70, 0, 70/ azimuth). Stimuli were recorded using an artificial head with microphones embedded in the "auditory canals" to capture the interaural time and level differences as well as some of the filter properties of the outer ear structures as auditory spatial cues, thus creating a realistic virtual auditory space.

The impact of catechol-O-methyltransferase and dopamine D4 receptor genotypes on neurophysiological markers of performance monitoring.

Dynamic adaptations of one's behavior by means of performance monitoring are a central function of the human executive system, that underlies considerable interindividual variation. Converging evidence from electrophysiological and neuroimaging studies in both animals and humans hints at the importance of the dopaminergic system for the regulation of performance monitoring. Here, we studied the impact of two polymorphisms affecting dopaminergic functioning in the prefrontal cortex [catechol-O-methyltransferase (COMT) Val108/158Met and dopamine D4 receptor (DRD4) single-nucleotide polymorphism (SNP)-521] on neurophysiological correlates of performance monitoring.

[Scurvy--a wrongly forgotten avitaminosis].

We treated a chronic alcoholic patient who showed all the symptoms of scurvy (petechiae, greyish skin colour, areas of thinning hair on the head, gingivitis, elevated liver enzyme levels, hyponatraemia, hypalbuminaemia and hypothyroidism) at admission. Even today, alcoholics and chronically ill people in particular can develop symptoms of diet-related vitamin C deficiency.

Automatic and attentive processing of sounds in cochlear implant patients - electrophysiological evidence.

Purpose: Processing auditory scenes requires the automatic detection of unexpected acoustic irregularities which allows to reorient the attentional focus for further in-depth analysis. Even if cochlea implants (CI) may partly restore hearing capabilities in patients suffering from profound peripheral deafness, CI users complain about difficulties in identifying novel and unexpected acoustic events. To assess whether this impairment is attributable to preattentive auditory deficits, impaired automatic orienting to novel events and/or to deficits in attentional processing we recorded event-related potentials (ERPs) in an auditory novelty oddball paradigm.

Perception of emotional speech in Parkinson's disease.

Nonmotor symptoms in Parkinson's disease (PD) involving cognition and emotionality have progressively received attention. The objective of the present study was to investigate recognition of emotional prosody in patients with PD (n = 14) in comparison to healthy control subjects (HC, n = 14). Event-related brain potentials (ERP) were recorded in a modified oddball paradigm under passive listening and active target detection instructions.

Crossmodal attention effects on brain responses to different stimulus classes.

Background: Attending to a point in space in one modality may facilitate processing to information from the same region in another modality. The involvement of sensory-specific cortical areas in intramodal and crossmodal selective spatial attention can be assessed with event-related brain potentials (ERPs). ERPs were recorded in two groups of young participants (each n = 11).

Selective loss of timbre perception for keyboard and percussion instruments following a right temporal lesion.

We report the case of a 65-year-old man WDK, who experienced selective loss of timbre perception for keyboard and percussion instruments following a right temporal stroke comprising the anterior superior and medial gyrus and parts of the insular region. Formerly an avid listener to music, the sound of an orchestra appeared to be "flat" to him. WDK and a matched control subject underwent a detailed neuropsychological test battery covering basic auditory function (audiometry and just notable difference for pitch shifts), specific auditory function (recognition of environmental sounds), specific musical functions like discrimination of pitch, interval, contour, rhythm and metre, recognition of familiar melodies, emotional responsiveness, perception of timbre and auditory spectral analysis.

Transcranial magnetic stimulation to the parietal lobes reduces detection of contralateral somatosensory stimuli.

Objectives: Neglect has been described in patients with lesions of the parietal cortex and has been interpreted as a disorder of the allocation of spatial attention. The persistence of neglect has been linked to poor rehabilitation outcome in patients suffering from acute stroke. Transcranial magnetic stimulation (TMS) applied to the parietal cortex has been shown to induce changes in the perception of stimuli including tactile stimulation of the fingers contra- and ipsilateral to the stimulated hemisphere.

Specialization of the specialized: electrophysiological investigations in professional musicians.

Several event-related brain potential (ERP) studies examining the processing of auditory stimuli by professional musicians compared with non-musicians are reviewed. In the first study, musicians (string players) and non-musicians attended to one of two streams of auditory stimuli characterized by a specific pitch. Musicians showed a prolonged ERP attention effect, the late portion of which was more frontally distributed than was that of the non-musicians.

Preattentive evaluation of multiple perceptual streams in human audition.

To analyze an auditory scene, the segregation of the input into separate streams of information is necessary. Here, the mismatch negativity (MMN) of the event-related potential was used to trace the number of simultaneously monitored streams in auditory scene analysis. Subjects passively listened to sounds belonging to either one, two, or three auditory streams defined by spatial position and pitch.

Tracking of multiple sound sources defined by interaural time differences: brain potential evidence in humans.

Among other cues, interaural time differences (ITD) can be used to compute the location of a sound. To investigate whether ITD can be used for the preattentive detection of sounds coming from a different location than standard sounds (P=0.7, no ITD), left and right 'far' (900 micros ITD, 80 degrees excentricity) and 'near ' (300 micros ITD, 30 degrees ) deviant stimuli (each deviant P=0.

The fate of sounds in conductors' brains: an ERP study.

Professional music conductors are required to home in on a particular musician but at the same time have to monitor the entire orchestra. It was hypothesized that this unique experience should be reflected by superior auditory spatial processing. Event-related brain potentials were obtained, while conductors, professional pianists, and non-musicians listened to sequences of bandpass-filtered noise-bursts presented in random order from six speakers, three located in front and three to the right of the subjects.

Tourette syndrome and obsessive-compulsive disorder: event-related brain potentials show similar mechanisms [correction of mechansims] of frontal inhibition but dissimilar target evaluation processes.

Objectives: Tourette Syndrome (TS) and Obsessive-Compulsive Disorders (OCD) share many clinical similarities and show a strong comorbidity. Current theories view a frontal-striatal dysfunction as the underlying cause of many clinical aspects of both disorders. This study sought to investigate mechanisms of conceptual integration and attention in both disorders.

Effects of subthalamic nucleus (STN) stimulation on motor cortex excitability.

Background: Deep brain stimulation of the internal global pallidus (GPi) and the subthalamic nucleus (STN) has become a treatment alternative in advanced PD. Although the effects of GPi stimulation have been examined recently, little is known about STN stimulation effects on motor cortex excitability.

Methods: The effects of STN stimulation were studied in eight patients with advanced PD using paired-pulse transcranial magnetic stimulation (TMS) in comparison with healthy control subjects.

Excessive action monitoring in Tourette syndrome.

Tourette Syndrome (TS) has been related to hyperactive basal-ganglia thalamocortical pathways. This suggests that action monitoring might also be hyperactive. The present study used the event-related brain potential (ERP) technique to investigate this hypothesis.

The costs of freedom: an ERP -- study of non-canonical sentences.

Objectives: The present investigation explored the electrophysiological correlates of working memory during sentence comprehension.

Methods: Event-related brain potentials (ERP) were recorded from 29 channels in 22 subjects, while they read German sentences having subject-first (canonical) or object-first (non-canonical) word orders.

Results: Three different ERP effects were observed: a negativity (maximum at Fc5) differentiating unambiguous object-first and subject-first sentences, interpreted as reflecting the demands of the object-first sentences on working memory; a second negativity (maximum at F7) to the subject noun-phrase in object-first sentences, interpreted as indicating retrieval of verbal material.

Implicit memory for words played during isoflurane- or propofol-based anesthesia: the lexical decision task.

Background: Unconscious processing of words during general anesthesia has been suggested after surgery with several tests of implicit memory. Patients can neither recall those words nor do they have explicit memories of other intraoperative events. It is unclear to what degree information is processed during general anesthesia and which tests are best suited to detect implicit memory.

Discrepant target detection and action monitoring in obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) has been related to altered mechanisms of action monitoring and target detection, and it has been hypothesized that hyperactive striatal-cortical circuits constitute the underlying pathophysiology. This study used event-related brain potentials (ERPs) to explore this hypothesis. A choice reaction time experiment was carried out in a group of OCD patients and a normal comparison group.