Posters: Neuropsychology

Most accounts explain motion sickness (MS) as a symptom of conflict between sensory input and the mental model of body movement. The visual oddball P3 and the habituation of auditory event-related potentials provide a measure of the ability of the brain to predict sensory input, and preliminary findings point to an association with MS, specifically drowsiness symptoms and heightened arousal. In the present study, participants were confronted with an MS-inducing condition (roller coaster) or a control condition (straight drive) in a virtual reality environment. Before and after the virtual reality exposure, the participants completed an MS questionnaire and were presented with an auditory paired click paradigm and a visual oddball paradigm. In the condition with high MS, susceptible participants showed reduced habituation to the repetitive auditory stimulation, as measured by auditory evoked potentials in the paired click paradigm. MS was furthermore associated with changes in pupil diameter. Auditory evoked potentials and oddball P3 also predicted MS susceptibility. Our results demonstrate that MS is linked to arousal and altered processing of predictable sensory inputs.

Accumulating evidence suggests that activity in the anterior cingulate cortex after observed actions reflects an action prediction error rather than, as previously thought, the coding of response accuracy. This process seems to be modulated by trait empathy, but the underlying mechanisms remain to be explored. In this study we aimed to examine these mechanisms further by applying a paradigm in which observer participants’ expectations concerning the outcome of the actions of an observed person were modulated by two experimental manipulations. These were true vs. false-belief of the observed person, which we expected to be especially dependent on empathy (as was shown by previous studies on false-belief tasks) as well as task difficulty (easy vs. hard), which we expected to be less dependent on empathy. Empathy and expectation affected event-related-potential amplitudes between 100 and 250 ms after the observed response: less expected events, that is, correct answers in the false-belief condition and incorrect answers in the true-belief condition, led to higher amplitudes compared to more expected events in easy trials, but this effect emerged only for highly empathic individuals. Interestingly, behavioral measures of expectation were similarly affected by empathy, suggesting that empathy helps expectation formation and that these expectations then affect electrophysiological responses.

The premotor cortex (PMC) is known to be part of a brain network subserving motor control, raising the question for its significance in motor learning. While the primary motor cortex (M1) plays a crucial role in the acquisition of a newly learned motor sequence, the precise impact of the PMC on subsequent consolidation remains less clear. The present study aims at investigating the role of the left PMC for early consolidation of a motor sequence after training on serial reaction time task (SRTT). Anodal, cathodal tDCS and sham-stimulation were applied to the left PMC in 18 healthy non-musicians 30 minutes after SRTT training with the right hand. Reaction times were measured prior to SRTT training (t1), at the end of training (t2), directly after tDCS (t3) and after overnight sleep (t4). The analysis revealed a significant facilitation of reaction times in sequential trials after anodal tDCS at t3, whereas no further significant improvement was evident at t4 (after overnight sleep). In contrast to this, cathodal stimulation yielded a significant reduction of reaction times after overnight sleep (t4). Reaction times at t4 did not differ between cathodal and anodal stimulation. No significant effects were found following sham-stimulation. The results support the hypothesis of a causal involvement of the PMC in early consolidation. In particular, the data imply that anodal tDCS can facilitate early motor sequence consolidation. Noteworthy, the impact of a single tDCS application is of short duration and remediated by progression of time and / or sleep.

We examined how the valence of augmented feedback influences motor learning, more specifically immediate adaptive behavior after feedback. For that purpose, event-related potentials (ERPs) in the EEG were scrutinized in learning a complex arm-movement sequence and the predictive value of different ERPs was analyzed for trial-to-trial behavioral adjustments during practice. Twenty-four healthy subjects (13 female; 22.1 years; SD ±3.4) practiced one session with 192 feedback trials according to an adaptive bandwidth feedback approach with a high informational level of feedback information (i.e., direction and magnitude of errors). The bandwidth for successful performance (increase of a score for a monetary competition) was adaptively manipulated in terms of the current performance level to obtain a balanced feedback rate regarding positive and negative valence. This allowed a variation of feedback-valence without a confounding by success rate (and hence outcome expectations). Consistent with our hypotheses, the EEG data showed a valence effect for the feedback-related negativity (FRN) and a later fronto-central component (Late-Fronto-Central-Positivity; LFCP) at the FCz electrode as well as for the P300 at the Pz electrode. Behavioral adjustments were larger after feedback with negative valence and they were predicted by the LFCP, but not by the FRN or the P300. The data supports the assumption that learning in contexts with availability of high level of feedback information relies more on processes associated to supervised learning (reflected by the LFCP) than on reinforcement learning (reflected by the FRN).

Size congruity, Spatial Numerical Association of Response Codes (SNARC), and numerical distance effects are distinct instances of how spatial constituents enter the symbolic number representation. Behavioral studies have suggested that these effects involve distinct processing stages but in electroencephalogram (EEG) evoked potentials are selective to all. To settle the question of their interdependence, we applied a factorial design encompassing all three effects, combined with EEG measurement, comparing across identical visual stimuli for the numerical distance and SNARC condition. The results show that all effects arise early, around 100 ms, with a hemispheric specificity. Whereas no dependency between size congruity and SNARC effects was found, the numerical distance effect was influenced by the lateralized response conditions of the SNARC effect. These results suggest independence of size congruity and SNARC effect, but dependency between numerical distance and SNARC effect. The lateralized character of the effects may therefore be the key to their (in)dependency.

Neural oscillations play an important role in sensory and cognitive processing. Occipital oscillations in the alpha band (8 - 13 Hz) are closely related to perceptional and attentional mechanisms. In multiple studies, increased alpha power has been shown to reduce detection of hard-to-detect visual stimuli. Moreover, the phase of alpha oscillations prior to stimulus onset is critical to the detection of visual stimuli. This is explained by a shift in cortical excitability over the course of each alpha cycle. However, prior studies often used short presentation times of visual stimuli at perceptual threshold. Differing from previous studies, we now use longer presentation times (up to 1.5 s) to elucidate the question whether the same mechanisms hold for the perception of salient stimuli. To this end, we present participants with hard to distinguish but salient upright or tilted Gaussian gratings in a two-alternative forced choice task, while measuring occipital alpha activity. In accordance with previous research, we expect alpha power and phase prior to stimulus onset to differentiate between correctly and incorrectly identified stimuli. Additionally, since the potential perceptual inhibition subsides as the alpha oscillation progresses, we expect to find a correlation between alpha phase prior to stimulus onset and reaction times in correctly identified stimuli.

The reduced neuronal signal to expected stimuli, termed expectation suppression, is a widely examined phenomenon. It is often explained under the predictive coding theory, in which expected sensory input can be predicted through inferential processes (feedback and feedforward loops) in the visual cortex whereas surprising events lead to a signal increase. This phenomenon has been observed with different methods and for a wide range of stimuli. In this fMRI study, we aimed to investigate the role of prediction error signals in identity processing using ambient exemplar images of famous identities. Within one trial we showed either eight images of different identities (alternation), eight images of one identity (adaptation) or violated the adaptation sequence by changing the identity in the last image (expectation violation). Preliminary results suggest that alternation trials elicit the highest response in visual face processing areas whereas we find a significantly reduced mean BOLD signal for adaptation trials. Crucially for trials with an unexpected change of identity in the last step the neural response is higher than in the adaptation condition. This suggests that higher order expectations about person identity are violated which leads to a release of adaptation.

Patients with amnestic Mild Cognitive Impairment (aMCI) are at risk for further cognitive decline and development of Alzheimer’s dementia. Recent evidence suggests that, in addition to episodic memory deficits, aMCI patients show impairments in visual attention. In particular, studies using psychophysical paradigms of whole and partial report based on the theory of visual attention (TVA; Bundesen, 1990) demonstrated significant impairments in top-down control of attentional selection. The present study aims to evaluate whether and how such top-down control impairment is related to impairments in cognitive functions, as assessed with established neuropsychological test batteries (e.g. ACE-III, CERAD+) and daily life impairments, as assessed in structured interviews and questionnaires (CDR, BAYER-ADL, BADS-DEX). Patients with aMCI are recruited at the Jena University Hospital Memory Center. Following diagnosis of aMCI, based on comprehensive neuropsychological and neurological examination, they undergo a TVA-based task in order to derive parameter top-down control, i.e. the efficiency in task-related attentional prioritization of targets over distractors.