Electrophysiological correlates of reinforcement learning in young people with Tourette syndrome with and without co-occurring ADHD symptoms

Altered reinforcement learning is implicated in the causes of Tourette syndrome (TS) and attention-deficit/hyperactivity disorder (ADHD). TS and ADHD frequently co-occur but how this affects reinforcement learning has not been investigated. We examined the ability of young people with TS (n = 18), TS+ADHD (N = 17), ADHD (n = 13) and typically developing controls (n = 20) to learn and reverse stimulus-response (S-R) associations based on positive and negative reinforcement feedback. We used a 2 (TS-yes, TS-no) x 2 (ADHD-yes, ADHD-no) factorial design to assess the effects of TS, ADHD, and their interaction on behavioural (accuracy, RT) and event-related potential (stimulus-locked P3, feedback-locked P2, feedback-related negativity, FRN) indices of learning and reversing the S-R associations. TS was associated with intact learning and reversal performance and largely typical ERP amplitudes. ADHD was associated with lower accuracy during S-R learning and impaired reversal learning (significantly reduced accuracy and a trend for smaller P3 amplitude). The results indicate that co-occurring ADHD symptoms impair reversal learning in TS+ADHD. The implications of these findings for behavioural tic therapies are discussed

What if I told you: "You were wrong"? Brain potentials and behavioral adjustments elicited by feedback in a time-estimation task

Contains fulltext : 64370.pdf (publisher's version ) (Open Access)Recent theories have associated the error-related negativity (ERN/Ne) with the arrival of an error signal in the anterior cingulate cortex (Holroyd & Coles, 2002). This error signal is generated when negative events occur, particularly when they are unexpected, and the anterior cingulate uses the error signal to select among appropriate courses of action. We evaluated these ideas by replicating and extending previous studies of the ERN following performance feedback in which subjects receive feedback after making a time-production judgment. In three different conditions, subjects received (1) correct or incorrect feedback, (2) correct, incorrect-slow, or incorrect-fast feedback, and (3) the same as condition (2), but with the graded incorrect feedback as a function of the degree of error. Behavioral data indicated that subjects adjusted their time-estimation as a function of feedback: following incorrect feedback in condition (2), they shortened or lengthened their judgments, and in condition (3) the amount of adjustment was related to the suggested degree of error. An ERN following negative feedback was present in all three conditions, being largest in the first condition. However, we did not find any relationship between ERN amplitude and behavioral adjustments. These results are discussed in terms of current theories on error processing

Scalp topography of ultralate (C-fibres) evoked potentials following thulium YAG laser stimuli to tiny skin surface areas in humans.

AIM: To investigate (1) the scalp topography of ultralate laser evoked potentials (LEPs) related to C-fibre activation, which can directly be obtained by thulium YAG (Tm YAG) laser stimulation of tiny skin surface areas (about 0.23 mm(2)) and (2) the influence of the performance of a motor task on ultralate LEPs. METHODS: Laser stimuli were applied to the dorsum of the left hand. LEPs were recorded with 58 scalp electrodes from 9 healthy subjects in two different conditions, with and without a reaction time (RT) task (press a button upon detection). RESULTS: On high resolution electroenchephalogram recordings, ultralate LEPs were characterized by a broad positive component (peak latency: 1133+/-91 ms) with maximum amplitude about the vertex. Moreover, the performance of a RT task had no influence on latency, amplitude and topographical patterns of two maps chosen at the positive peak latency in ultralate LEPs. Nevertheless, a negative inflexion (latency 1300 ms) appeared after the positive component in the task condition possibly reflecting movement-related potentials. CONCLUSION: Tm YAG laser stimulation of tiny skin surface areas allows recording the dynamic scalp topography of ultralate (C-fibres) LEPs, with or without the performance of a RT task

Event-related potentials to schematic faces in social phobia

Social phobia has been associated with an attentional bias for angry faces. This study aimed at further characterising this attentional bias by investigating reaction times, heart rates, and ERPs while social phobics, spider phobics, and controls identified either the colour or the emotional quality of angry, happy, or neutral schematic faces. The emotional expression of angry faces did not interfere with the processing of their colour in social phobics, and heart rate, N170 amplitude and parietal late positive potentials (LPPs) of these subjects were also no different from those of non-phobic subjects. However, social phobics showed generally larger P1 amplitudes than non-phobic controls with spider phobic subjects in between. No general threat advantage for angry faces was found. All groups identified neutral schematic faces faster and showed larger late positive amplitudes to neutral than to emotional faces. Furthermore, in all groups the N170 was modulated by the emotional quality of faces. This effect was most pronounced in the emotion identification task

What if I told you: "You were wrong"? Brain potentials and behavioral adjustments elicited by feedback in a time-estimation task

Recent theories have associated the error-related negativity (ERN/Ne) with the arrival of an error signal in the anterior cingulate cortex (Holroyd & Coles, 2002). This error signal is generated when negative events occur, particularly when they are unexpected, and the anterior cingulate uses the error signal to select among appropriate courses of action. We evaluated these ideas by replicating and extending previous studies of the ERN following performance feedback in which subjects receive feedback after making a time-production judgment. In three different conditions, subjects received (1) correct or incorrect feedback, (2) correct, incorrect-slow, or incorrect-fast feedback, and (3) the same as condition (2), but with the graded incorrect feedback as a function of the degree of error. Behavioral data indicated that subjects adjusted their time-estimation as a function of feedback: following incorrect feedback in condition (2), they shortened or lengthened their judgments, and in condition (3) the amount of adjustment was related to the suggested degree of error. An ERN following negative feedback was present in all three conditions, being largest in the first condition. However, we did not find any relationship between ERN amplitude and behavioral adjustments. These results are discussed in terms of current theories on error processing