Prefrontal Neural Activity When Feedback Is Not Relevant to Adjust Performance

It has been shown that the rostral cingulate zone (RCZ) in humans uses both positive and negative feedback to evaluate performance and to flexibly adjust behaviour. Less is known on how the feedback types are processed by the RCZ and other prefrontal brain areas, when feedback can only be used to evaluate performance, but cannot be used to adjust behaviour. The present fMRI study aimed at investigating feedback that can only be used to evaluate performance in a word-learning paradigm. One group of volunteers (N = 17) received informative, performance-dependent positive or negative feedback after each trial. Since new words had to be learnt in each trial, the feedback could not be used for task-specific adaptations. The other group (N = 17) always received non-informative feedback, providing neither information about performance nor about possible task-specific adaptations. Effects of the informational value of feedback were assessed between-subjects, comparing trials with positive and negative informative feedback to non-informative feedback. Effects of feedback valence were assessed by comparing neural activity to positive and negative feedback within the informative-feedback group. Our results show that several prefrontal regions, including the pre-SMA, the inferior frontal cortex and the insula were sensitive to both, the informational value and the valence aspect of the feedback with stronger activations to informative as compared to non-informative feedback and to informative negative compared to informative positive feedback. The only exception was RCZ which was sensitive to the informational value of the feedback, but not to feedback valence. The findings indicate that outcome information per se is sufficient to activate prefrontal brain regions, with the RCZ being the only prefrontal brain region which is equally sensitive to positive and negative feedback

The Influence of Chronic Pain and Cognitive Function on Spatial-Numerical Processing

Chronic pain (CP) is linked to changes in cognitive function. However, little is known about its influence on number sense, despite the fact that intact numerical-spatial processing is a prerequisite for valid scale-based pain assessments. This study aimed to elucidate whether number sense is changed in CP, to determine if changes have an impact on pain assessments using pain rating scales and what patient factors might contribute. N = 42 CP patients and n = 42 matched controls were analyzed (age range: 33–68 years). Numerical-spatial abilities were investigated by using number line tasks, where participants either estimated the position of a given number (position marking) or the value of a predefined mark (number naming). Pain intensity was assessed using numerical rating (NRS), verbal rating (VRS), and visual analog (VAS) scales. Additional measures included attention and working memory, verbal intelligence, medication and depression. Results revealed that in number naming, patients deviated more from expected (correct) responses than controls, and that VAS scores were significantly higher than both NRS and VRS and correlated with deviations in position making. Changes in number naming were predicted by pain intensity, sex and IQ but not by attention, memory or opioid medication. This article presents new insight on which cognitive mechanisms are influenced by CP with the focus on numerical spatial abilities. It could therefore provide useful knowledge in developing new pain assessment tools specifically for patients suffering from CP

The Contribution of Cognitive Factors to Individual Differences in Understanding Noise-Vocoded Speech in Young and Older Adults

Noise-vocoded speech is commonly used to simulate the sensation after cochlear implantation as it consists of spectrally degraded speech. High individual variability exists in learning to understand both noise-vocoded speech and speech perceived through a cochlear implant (CI). This variability is partly ascribed to differing cognitive abilities like working memory, verbal skills or attention. Although clinically highly relevant, up to now, no consensus has been achieved about which cognitive factors exactly predict the intelligibility of speech in noise-vocoded situations in healthy subjects or in patients after cochlear implantation. We aimed to establish a test battery that can be used to predict speech understanding in patients prior to receiving a CI. Young and old healthy listeners completed a noise-vocoded speech test in addition to cognitive tests tapping on verbal memory, working memory, lexicon and retrieval skills as well as cognitive flexibility and attention. Partial-least-squares analysis revealed that six variables were important to significantly predict vocoded-speech performance. These were the ability to perceive visually degraded speech tested by the Text Reception Threshold, vocabulary size assessed with the Multiple Choice Word Test, working memory gauged with the Operation Span Test, verbal learning and recall of the Verbal Learning and Retention Test and task switching abilities tested by the Comprehensive Trail-Making Test. Thus, these cognitive abilities explain individual differences in noise-vocoded speech understanding and should be considered when aiming to predict hearing-aid outcome

Acute Effects of Aerobic Exercise on Executive Function and Attention in Adult Patients With ADHD

Aerobic exercise can improve cognitive functions in healthy individuals and in various clinical groups, which might be particularly relevant for patients with ADHD. This study investigated the effects of a single bout of aerobic exercise on attention and executive functions in adult patients with ADHD, including functional MRI to examine the underlying neural mechanisms. On two different days, 23 adult patients with ADHD and 23 matched healthy controls performed in a flanker task, while functional MR images were collected, following 30 min of continuous stationary cycling with moderate intensity as well as after a control condition (watching a movie). Behavioral performance and brain activation were tested for differences between groups and conditions and for interactions to investigate whether exercise improves executive function to a greater extent in patients compared to healthy controls. Exercise significantly improved reaction times in congruent and incongruent trials of the flanker task in patients with ADHD but not in healthy controls. We found no changes in brain activation between the two conditions for either group. However, a subgroup analysis of ADHD patients with a higher degree of cardiorespiratory fitness revealed decreased activation in premotor areas during congruent trials and in premotor and medial frontal cortex during incongruent trials in the exercise compared to the control condition. Our results indicate exercise-induced improvements in attention and processing speed in patients with ADHD, demonstrating that adult patients with ADHD may benefit from an acute bout of exercise. These findings could be of high relevance for developing alternative treatment approaches for ADHD. In addition, results of the current study contribute to elucidate the neurophysiological mechanisms underlying the beneficial effects of exercise on cognition and to better understand the role of cardiorespiratory fitness on these effects

Neural correlates of inter- and intra-individual saccadic reaction time differences in the gap/overlap paradigm

To examine the neural correlates of contextually differing control mechanisms in saccade initiation, we studied 18 subjects who performed two saccade paradigms in a pseudo-random order, while their eye movements were recorded in the MRI scanner (1.5 T). In the gap task the fixation point was extinguished 200 ms before target onset, and in the overlap task the fixation point vanished 500 ms after target onset. Subjects were asked to maintain stable fixation in the fixation period and to quickly saccade to peripherally presented targets. Inter-individual activation differences were assessed using regression analyses at the second level, with mean saccadic reaction time (SRT) of subjects as a covariate. To identify brain regions varying with trial-by-trial changes in SRTs, we included SRTs as a parametric modulation regressor in the general linear model. All analyses were regions of interest based and were performed separately for the gap and overlap conditions. For the gap paradigm, we did not obtain activation in regions previously shown to be involved in preparatory processes with much longer gap periods. Interestingly, both inter- and intra-individual variability analyses revealed a positive correlation of activation in frontal and parietal eye-movement regions with SRTs, indicating that slower saccade performance is possibly associated with higher cortical control. For the overlap paradigm, the trial-by-trial variability analysis revealed a positive correlation of activation in the right opercular inferior frontal gyrus with SRTs, possibly linked to fixation-related processes that have to be overcome to perform a speeded saccade in presence of a fixation point

Differences and similarities in working memory and episodic memory performance in patients with Parkinson’s Disease and Alzheimer’s Disease (German title: „Unterschiede und Gemeinsamkeiten im Arbeits- und episodischen Gedächtnis bei Morbus Parkinson und Alzheimer (PD_AD2)“)

The two primary objectives of this project are to compare the two groups of patients, patients with probable Alzheimer’s Disease (AD) and patients with probable Parkinson’s Disease Dementia (PDD) with regard to their working memory (primary endpoint 1) and episodic memory performance (primary endpoint 2) in a confirmatory manner

Effects of age on long term memory for degraded speech

Prior research suggests that acoustical degradation impacts encoding of items into memory, especially in elderly subjects. We here aimed to investigate whether acoustically degraded items that are initially encoded into memory are more prone to forgetting as a function of age. Young and old participants were tested with a vocoded and unvocoded serial list learning task involving immediate and delayed free recall. We found that degraded auditory input increased forgetting of previously encoded items, especially in older participants. We further found that working memory capacity predicted forgetting of degraded information in young participants. In old participants, verbal IQ was the most important predictor for forgetting acoustically degraded information. Our data provide evidence that acoustically degraded information, even if encoded, is especially vulnerable to forgetting in old age

Fatigue in patients with hypothalamic syndrome – A cross-sectional analysis of the German childhood-onset craniopharyngioma cohort

Objective: Patients with suprasellar tumors are at risk for hypothalamic syndrome (HS), including fatigue and excessive daytime sleepiness. The aim of this cross-sectional study was to determine the severity of fatigue in patients with and without HS. Methods: Patients diagnosed with CP or pilocytic astrocytoma were recruited from the KRANIOPHARYNGEOM studies. Eligibility criteria were availability of one completed Multidimensional Fatigue Inventory-20 (MFI-20) questionnaire and complete medical records on criteria for HS. The associations between HS and levels of fatigue symptoms (MFI-20 sum score) were assessed. MFI-20 scores were compared to sex- and age-matched reference values from a German normative population. Results: Data on 41 patients, with a median age of 22 years, were available for analyses of which 25 (61 %) patients presented with HS. After adjustment for age and sex, patients with HS reported higher scores in the physical (β= 3.39 [95 %-CI:1.18–5.60]) and sum MFI-20 (β=11.42 [95 %-CI:2.06–20.79]) domain than patients without HS. Compared to reference values, all patients reported higher mean scores in each fatigue domain. Abnormal self-reported daytime sleepiness was reported in 6 of 25 (24 %) patients with HS. Regardless of the level of daytime sleepiness in patients with HS, the reported fatigue scores were high. Daytime sleepiness did not correlate with fatigue. Conclusions: Fatigue symptoms are present in patients with CP. However, patients with HS are more affected with physical and overall fatigue. It is crucial in clinical practice, to distinguish between daytime sleepiness and fatigue and to target patients with HS

Brain-behaviour correlations in the insula and inferior frontal cortex.

<p>Correlation of subjects’ failure rates with the difference scores obtained from activation to both feedback values (ROI value negative feedback – ROI value positive feedback). Results of the correlation analyses are depicted for the left insula and inferior frontal cortex IFC. FB = feedback.</p