Predictive information and error processing : the role of medial-frontal cortex during motor control

We have recently provided evidence that an error-related negativity (ERN), an ERP component generated within medial-frontal cortex, is elicited by errors made during the performance of a continuous tracking task (O.E. Krigolson & C.B. Holroyd, 2006). In the present study we conducted two experiments to investigate the ability of the medial-frontal error system to evaluate predictive error information. In two experiments participants used a joystick to perform a computer-based continuous tracking task in which some tracking errors were inevitable. In both experiments, half of these errors were preceded by a predictive cue. The results of both experiments indicated that an ERN-like waveform was elicited by tracking errors. Furthermore, in both experiments the predicted error waveforms had an earlier peak latency than the unpredicted error waveforms. These results demonstrate that the medial-frontal error system can evaluate predictive error information

Reward positivity elicited by predictive cues

A recent theory holds that a component of the human event-related brain potential called the reward positivity reflects a reward prediction error signal. We investigated this idea in gambling-like task in which, on each trial, a visual stimulus predicted a subsequent rewarding or nonrewarding outcome with 80% probability. Consistent with earlier results, we found that the reward positivity was larger to unexpected than to expected outcomes. In addition, we found that the predictive cues also elicited a reward positivity, as proposed by the theory. These results indicate that the reward positivity reflects the initial assessment of whether a trial will end in success or failure and the reappraisal of that information once the outcome actually occurs. NeuroReport 22:249-252 (C) 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Learning to become an expert : reinforcement learning and the acquisition of perceptual expertise

To elucidate the neural mechanisms underlying the development of perceptual expertise, we recorded ERPs while participants performed a categorization task. We found that as participants learned to discriminate computer-generated "blob'' stimuli, feedback modulated the amplitude of the errorrelated negativity (ERN)-an ERP component thought to reflect error evaluation within medial-frontal cortex. As participants improved at the categorization task, we also observed an increase in amplitude of an ERP component associated with object recognition (the N250). The increase in N250 amplitude preceded an increase in amplitude of an ERN component associated with internal error evaluation (the response ERN). Importantly, these electroencephalographic changes were not observed for participants who failed to improve on the categorization task. Our results suggest that the acquisition of perceptual expertise relies on interactions between the posterior perceptual system and the reinforcement learning system involving medial-frontal cortex

Can an Evaluation of Students’ Stress Levels Help us Manage Anxiety During OSCEs and Other Assessment Modalities?

With an increased awareness of mental health issues, in both the student population and the veterinary profession in general, it is important that we obtain a greater understating of the stress experienced by students so as to better prepare them to deal with stress and ameliorate any negative effects it may have on performance. This study aims to characterise various measurements of stress (e.g. HRV, EEG, cortisol, self-report questionnaire) in students within the School of Veterinary Medicine in familiar test modalities, focussing on OSCE assessment. We would also investigate how performance is impacted and what potential factors may influence stress levels. Ultimately, our aim would be to evaluate intervention strategies to assess if students stress levels and performance can be improved

Electroencephalographic correlates of target and outcome errors

Different neural systems underlie the evaluation of different types of errors. Recent electroencephalographic evidence suggests that outcome errors-errors indicating the failure to achieve a movement goal-are evaluated within medial-frontal cortex (Krigolson and Holroyd 2006, 2007a, b). Conversely, evidence from a variety of manual aiming studies has demonstrated that target errors-discrepancies between the actual and desired motor command brought about by an unexpected change in the movement environment-are mediated within posterior parietal cortex (e.g., Desmurget et al. 1999, 2001; Diedrichsen et al. 2005). Here, event-related brain potentials (ERP) were recorded to assess medial-frontal and parietal ERP components associated with the evaluation of outcome and target errors during performance of a manual aiming task. In line with previous results (Krigolson and Holroyd 2007a), we found that target perturbations elicited an ERP component with a parietal scalp distribution, the P300. However, the timing of kinematic changes associated with accommodation of the target perturbations relative to the timing of the P300 suggests that the P300 component was not related to the online control of movement. Instead, we believe that the P300 evoked by target perturbations reflects the updating of an internal model of the movement environment. Our results also revealed that an error-related negativity, an ERP component typically associated with the evaluation of speeded response errors and error feedback, was elicited when participants missed the movement target. Importantly, this result suggests that a reinforcement learning system within medial-frontal cortex may play a role in improving subsequent motor output

Using brain potentials to understand prism adaptation: the error-related negativity and the P300

Prism adaptation (PA) is both a perceptual-motor learning task as well as a promising rehabilitation tool for visuo-spatial neglect (VSN) – a spatial attention disorder often experienced after stroke resulting in slowed and/or inaccurate motor responses to contralesional targets. During PA, individuals are exposed to prism-induced shifts of the visual-field while performing a visuo-guided reaching task. After adaptation, with goggles removed, visuo-motor responding is shifted to the opposite direction of that initially induced by the prisms. This visuo-motor aftereffect has been used to study visuo-motor learning and adaptation and has been applied clinically to reduce VSN severity by improving motor responding to stimuli in contralesional (usually left-sided) space. In order to optimize PA’s use for VSN patients, it is important to elucidate the neural and cognitive processes that alter visuomotor function during PA. In the present study, healthy young adults underwent PA while event-related potentials (ERPs) were recorded at the termination of each reach (screen-touch), then binned according to accuracy (hit vs. miss) and phase of exposure block (early, middle, late). Results show that two ERP components were evoked by screen-touch: an early error-related negativity (ERN), and a P300. The ERN was consistently evoked on miss trials during adaptation, while the P300 amplitude was largest during the early phase of adaptation for both hit and miss trials. This study provides evidence of two neural signals sensitive to visual feedback during PA that may sub-serve changes in visuomotor responding. Prior ERP research suggests that the ERN reflects an error processing system in medial-frontal cortex, while the P300 is suggested to reflect a system for context updating and learning. Future research is needed to elucidate the role of these ERP components in improving visuomotor responses among individuals with VSN

Can an Evaluation of Students’ Stress Levels Help us Manage Anxiety During OSCEs and Other Assessment Modalities?

With an increased awareness of mental health issues, in both the student population and the veterinary profession in general, it is important that we obtain a greater understating of the stress experienced by students so as to better prepare them to deal with stress and ameliorate any negative effects it may have on performance. This study aims to characterise various measurements of stress (e.g. HRV, EEG, cortisol, self-report questionnaire) in students within the School of Veterinary Medicine in familiar test modalities, focussing on OSCE assessment. We would also investigate how performance is impacted and what potential factors may influence stress levels. Ultimately, our aim would be to evaluate intervention strategies to assess if students stress levels and performance can be improved