Martina Rieger

Inhibition of ongoing responses in patients with Parkinson’s disease

Objectives: We investigated the involvement of the basal ganglia in inhibiting ongoing responses in patients with Parkinson’s disease (PD). Methods: Thirty two patients with PD and 31 orthopaedic controls performed the stop signal task, which allows an estimation of the time it takes to inhibit an ongoing reaction (stop signal reaction time, SSRT). Results: Patients with PD showed significantly longer SSRTs than the controls. This effect seemed to be independent of global cognitive impairment and severity of PD. Furthermore, in the PD patients, there was no significant relation between general slowing and inhibitory efficiency. Conclusions: Our results provide evidence for involvement of the basal ganglia in the inhibition of ongoing responses.

Inhibition of ongoing responses following frontal, nonfrontal and basal ganglia lesions

The authors investigated the role of the frontal lobes and the basal ganglia in the inhibition of ongoing responses. Seventeen patients with frontal lesions (FG), 20 patients with lesions outside the frontal cortex (NFG), 8 patients with lesions to the basal ganglia (BG), and 20 orthopedic controls (OG) performed the stop-signal task that allows the estimation of the time it takes to inhibit an ongoing reaction (stop signal reaction time [SSRT]). The FG and the BG showed significantly longer SSRTs than the OG. Within the FG, patients with right and bilateral lesions showed significantly longer SSRTs than patients with left lesions. Results provide evidence for a role of the frontal lobes and the basal ganglia in the inhibition of ongoing responses.

Inhibitory after-effects in the stop signal paradigm

The inhibition of responses to interfering stimuli in a trial results in longer reaction times in the following trial in which to-be-ignored stimuli become targets. This is due to the fact that the residual inhibition of the distractor must be overcome before the relevant response can be produced. Such negative priming effects are wellknown inhibitory after-effects and the focus of intensive research. However, it seems reasonable to assume that the use of inhibitory processes leaves measurable after-effects in a variety of other tasks and situations. Therefore, the aim of the present study was to investigate whether the after-effects of inhibition could be obtained in a task measuring motor inhibition (i.e. the stop signal task). Our results indicate that inhibitory after-effects were present in the stop signal task whether or not participants were successful in inhibiting their reactions. Moreover, inhibitory after-effects were greater when both trials consisted of the same primary task properties. Strategic effects might explain part of the results, but there is evidence that a specific inhibition of either the stimulus, or the response to that stimulus, or both plays a role in the constitution of the after-effects.

Automatic keypress activation in skilled typing

The assumption that letters automatically activate corresponding keypresses in skilled typing was investigated. Participants responded to the color of letters (congruent condition: responding finger was the one usually used to type the letter). Participants skilled in typing showed a congruency effect: unskilled participants did not (Experiment 1). The automatic activation included characteristics of the movement usually performed to type the letters (Experiment 2). Responding with crossed hands on an external response device (Experiment 3) provided evidence for effector-dependent representations only, whereas responding on a keyhoard (Experiment 4) resulted in evidence for effector-dependent and spatial representations. Thus, motoric skill proficiency is accompanied by automatic activation processes that probably contribute to high performance levels.

When hearing turns into playing: Movement induction by auditory stimuli in pianists

In this study, pianists were tested for learned associations between actions (movements on the piano) and their perceivable sensory effects (piano tones). Actions were examined that required the playing of two-tone sequences (intervals) in a four-choice paradigm. In Experiment 1, the intervals to be played were denoted by visual note stimuli. Concurrently with these imperative stimuli, task-irrelevant auditory distractor intervals were presented (“potential” action effects, congruent or incongruent). In Experiment 2, imperative stimuli were coloured squares, in order to exclude possible influences of spatial relationships of notes, responses, and auditory stimuli. In both experiments responses in the incongruent conditions were slower than those in the congruent conditions. Also, heard intervals actually “induced” false responses. The reaction time effects were more pronounced in Experiment 2. In nonmusicians (Experiment 3), no evidence for interference could be observed. Thus, our results show that in expert pianists potential action effects are able to induce corresponding actions, which demonstrates the existence of acquired action–effect associations in pianists.

Nobody Is Perfect: ERP Effects Prior to Performance Errors in Musicians Indicate Fast Monitoring Processes

Background One central question in the context of motor control and action monitoring is at what point in time errors can be detected. Previous electrophysiological studies investigating this issue focused on brain potentials elicited after erroneous responses, mainly in simple speeded response tasks. In the present study, we investigated brain potentials before the commission of errors in a natural and complex situation. Methodology/Principal Findings Expert pianists bimanually played scales and patterns while the electroencephalogram (EEG) was recorded. Event-related potentials (ERPs) were computed for correct and incorrect performances. Results revealed differences already 100 ms prior to the onset of a note (i.e., prior to auditory feedback). We further observed that erroneous keystrokes were delayed in time and pressed more slowly. Conclusions Our data reveal neural mechanisms in musicians that are able to detect errors prior to the execution of erroneous movements. The underlying mechanism probably relies on predictive control processes that compare the predicted outcome of an action with the action goal.

Processing expectancy violations during music performance and perception: An erp study

Musicians are highly trained motor experts with pronounced associations between musical actions and the corresponding auditory effects. However, the importance of auditory feedback for music performance is controversial, and it is unknown how feedback during music performance is processed. The present study investigated the neural mechanisms underlying the processing of auditory feedback manipulations in pianists. To disentangle effects of action-based and perception-based expectations, we compared feedback manipulations during performance to the mere perception of the same stimulus material. In two experiments, pianists performed bimanually sequences on a piano, while at random positions, the auditory feedback of single notes was manipulated, thereby creating a mismatch between an expected and actually perceived action effect (action condition). In addition, pianists listened to tone sequences containing the same manipulations (perception condition). The manipulations in the perception condition were either task-relevant (Experiment 1) or task-irrelevant (Experiment 2). In action and perception conditions, event-related potentials elicited by manipulated tones showed an early fronto-central negativity around 200 msec, presumably reflecting a feedback ERN/N200, followed by a positive deflection (P3a). The early negativity was more pronounced during the action compared to the perception condition. This shows that during performance, the intention to produce specific auditory effects leads to stronger expectancies than the expectancies built up during music perception.

Inhibition of ongoing responses in patients with traumatic brain injury

In addition to slowness of information processing, it is often assumed that executive functions are deficient in patients with traumatic brain injuries (TBI). The aim of this study was to investigate a specific executive function, the inhibition of ongoing responses in TBI. Twenty-seven patients with TBI and 27 orthopedic patients (OC) performed the stop signal task, which allows the estimation of the time it takes to inhibit an ongoing response. Contrary to expectations, patients with TBI did not perform worse than the OC in the inhibition of ongoing responses. Furthermore, subgroups of the TBI, with frontal and nonfrontal lesions, and with focal versus diffuse damage, did not show any differences in performance. None of the clinical, demographic or neuropsychological data had a significant relationship to inhibition time, apart from age, which showed a significant relationship only in the TBI. It seems likely that deficits in the inhibition of ongoing responses are not very common after TBI.

Compensation for and adaptation to changes in the environment

Human motor behavior is remarkably accurate, even though many everyday skills require flexible adjustments between motor activity and its consequences in extracorporeal space. The present study addressed two questions: first, how do people compensate for unpredictable changes in the environment, and second, how do they adapt to such changes? In Experiment 1, participants repeatedly and continuously drew up and down strokes on a writing pad. After drawing under a base mapping, either (a) a change of target position, or (b) a change of gain, or (c) both occurred. Compensation for gain changes occurred later than compensation for changes in target position. In addition, there were aftereffects of the previous movement in accuracy and movement time. Adaptation to changes occurred in reference to extracorporeal space, with motor constraints as a limiting factor. In Experiment 2 we obtained similar effects when participants had more time to adapt. The view that movements are planned in reference to their goals in extracorporeal space is supported.

Representing others' actions: The role of expertise in the aging mind

A large body of evidence suggests that action execution and action observation share a common representational domain. To date, little is known about age-related changes in these action representations that are assumed to support various abilities such as the prediction of observed actions. The purpose of the present study was to investigate (a) how age affects the ability to predict the time course of observed actions; and (b) whether and to what extent sensorimotor expertise attenuates age-related declines in prediction performance. In a first experiment, older adults predicted the time course of familiar everyday actions less precisely than younger adults. In a second experiment, younger and older figure skating experts as well as age-matched novices were asked to predict the time course of figure skating elements and simple movement exercises. Both young age and sensorimotor expertise had a positive influence on prediction performance of figure skating elements. The expertise-related benefit did not show a transfer to movement exercises. Together, the results suggest a specific decline of action representations in the aging mind. However, extensive sensorimotor experience seems to enable experts to represent actions from their domain of expertise more precisely even in older age.