Blocked versus randomized presentation modes differentially modulate feedback-related negativity and P3b amplitudes

ObjectiveElectrophysiological studies on feedback processing typically use a wide range of feedback stimuli which might not always be comparable. The current study investigated whether two indicators of feedback processing – feedback-related negativity (FRN) and P3b – differ for feedback stimuli with explicit (facial expressions) or assigned valence information (symbols). In addition, we assessed whether presenting feedback in either a trial-by-trial or a block-wise fashion affected these ERPs.MethodsEEG was recorded in three experiments while participants performed a time estimation task and received two different types of performance feedback.ResultsOnly P3b amplitudes varied consistently in response to feedback type for both presentation types. Moreover, the blocked feedback type presentation yielded more distinct FRN peaks, higher effect sizes, and a significant relation between FRN amplitudes and behavioral task performance measures.ConclusionBoth stimulus type and presentation mode may provoke systematic changes in feedback-related ERPs. The current findings point at important potential confounds that need to be controlled for when designing FRN or P3b studies.SignificanceStudies investigating P3b amplitudes using mixed types of stimuli have to be interpreted with caution. Furthermore, we suggest implementing a blocked presentation format when presenting different feedback types within the same experiment.     

Event-related components of the punishment and reward sensitivity

ObjectiveThe present study investigated the properties of feedback-related negativity (FRN) and P3 component of the event-related potentials (ERPs) and their neural sources localization as neurocognitive correlates of the behavioural inhibition and behavioural activation systems (BIS/BAS). The association between BIS/BAS function and anterior cortical asymmetry was tested.MethodsFifty right-handed women were investigated with 30-channel recordings during an instrumental Go/No-Go learning task. ERPs were elicited to feedback signals indicating monetary losses and monetary gains. Learning performance, FRN, and P3 amplitude and latency measures were calculated and related to BIS and BAS measures by means of ANOVA and correlation analysis. The neural sources of FRN and P3 components of the ERPs were estimated using LORETA software. A resting EEG-alpha-power (8–13 Hz) asymmetry measure was obtained.ResultsHigh levels of Reward Responsiveness (RR), a first order factor of the BAS, were associated with shorter RTs and enhanced positive feelings. The FRN was larger to signals indicating monetary Loss as compared to monetary Gain and enhanced with higher BIS and individual learning ability. Higher RR scores were related to greater left-sided resting frontal cortical asymmetry associated with approach orientation. High-RR subjects, as compared to Low-RR ones, had a smaller P3 amplitude for Go/Loss signals. The P3 latency to No-Go/Gain signals was the best positive predictor of RR. LORETA source localization for the FRN component displayed significantly higher brain electrical activity in left-fusiform gyrus and right superior temporal gyrus to monetary Loss in comparison to monetary Gain after incorrect No-Go responses. For the P3 wave, the monetary Loss produced significantly higher activations in the left superior parietal lobule, right postcentral gyrus, and in the ACC.ConclusionThe FRN was sensitive to cues of punishment and higher BIS was uniquely related to a larger FRN amplitude on No-Go/Loss trials, linking BIS with conflict monitoring and sensitivity to No-Go cues. Furthermore, the significant interaction found between BIS and RR on FRN amplitude together with the findings linking High-RR levels with shorter RTs, smaller P3 amplitudes and enhanced positive feelings are in line with the hypothesis that both BIS and BAS have the potential to influence punishment-mediated and reward-mediated behaviour.SignificanceResults open up new perspectives for future investigations on the relationship between BIS/BAS measures and ERP components to monetary reward during learning.     

Reward context sensitivity impairment following severe TBI: an event-related potential investigation.

Many rehabilitation protocols following traumatic brain injury (TBI) utilize reinforcement and reward to influence behavior and facilitate recovery; however, previous studies suggest survivors of severe TBI demonstrate impairments in contingency utilization and sensitivity. The precise neurobiological mechanisms underlying these deficits have not been thoroughly explored, but can be examined using the "feedback-related negativity" (FRN)--an event-related potential (ERP) component evoked following performance or response feedback (e.g., whether a monetary reward is obtained) with a larger FRN following unfavorable than favorable outcomes--particularly when unfavorable feedback occurs in the context of high reward probability. We examined ERPs elicited by favorable (monetary gain: "reward") and unfavorable (no monetary gain: "non-reward") feedback during a guessing task where probability of reward outcome was manipulated in survivors of severe TBI and demographically matched healthy participants. Consistent with previous findings, controls showed larger amplitude FRN to non-reward feedback and the largest amplitude FRN following a non-reward when reward probability context was greatest. In contrast, FRN in TBI participants did not significantly differentiate non-reward from reward trials and their FRN was largest to reward trials in the low reward probability context. Findings implicate an electrophysiological marker of impaired reward context sensitivity following severe TBI.     

Voxel-based morphometry reveals extra-nigral atrophy patterns associated with dopamine refractory cognitive and motor impairment in parkinsonism

ObjectivesTo determine overall patterns of brain atrophy associated with memory, executive function (EF) and dopamine non-responsive motor measures in older parkinsonian patients.DesignForty-three older PD patients (≥65 years) and matched controls underwent a neurological examination (Unified Parkinson's Disease Rating Scale, separated into dopamine responsive and dopamine non-responsive signs) and neuropsychological testing (memory: California Verbal Learning Test (CVLT)) and a composite of index of executive function (EF): Stroop Interference, Trail Making Test Part B, and digit ordering. All underwent volumetric MRI scans analyzed using voxel-based morphometry (VBM). Group comparisons, and the correlations between MRI gray and white matter volume and motor and cognitive measures were controlled for age, sex and intracranial volume. Cerebellar volume was independently measured using a validated extraction method.ResultsPatients and controls were matched for demographics and global cognitive measures. VBM indicated significant gray matter (GM) atrophy in the cerebellum in PD and was confirmed independently. Poor memory was associated with GM atrophy in the left (uncus, middle temporal and fusiform gyri) and right temporal lobes and left putamen. Dopamine non-responsive motor signs and EF were associated with caudate atrophy. EF was also associated with GM atrophy in the middle temporal gyri, the left precuneus and cerebellum.ConclusionsCortical and striatal atrophy were associated with dopamine non-responsive motor signs and cognitive impairment and provide a morphologic correlate for progression of PD. Cerebellar atrophy was found in older PD patients.     

Motor sequencing in older adulthood: relationships with executive functioning and effects of complexity

Objective: Older adults’ motor sequencing performance is more reliant on executive functioning (EF) and more susceptible to complexity than that of younger adults. This study examined for which aspects of motor sequencing performance these relationships hold. Methods: Fifty-seven younger and 90 non-demented, community-dwelling, older adults completed selected subtests from the Delis–Kaplan Executive Function System as indices of EF and component processes (CP; graphomotor speed; visual scanning; etc.), as well as a computerized motor sequencing task (Push Turn Taptap task; PTT). The PTT requires participants to perform motor sequences that become progressively more complex across the task’s four blocks, and is designed to assess action planning, action learning, and motor control speed and accuracy. Results: Hierarchical regressions using each discrete aspect of performance as the dependent variable revealed that action planning is the only aspect of motor sequencing that is uniquely related to EF (beyond the CP composite) for both age groups. Action learning and motor control accuracy are uniquely associated with EF for older adults only, and only if the sequences are complex. Component processes do not fully account for the unique relationships between motor sequencing and EF in older adults. Conclusions: These results clarify prior findings by showing (a) more aspects of motor sequencing relate to EF for older compared to younger adults and (b) for these unique relationships, EF is only related to action during the generation of sequences that are complex. These findings further our understanding of how aging shapes the links between EF and motor actions, and can be used in evidence-based and theoretically driven intervention programs that promote healthy aging.     

Transcranial Magnetic Stimulation-EEG Biomarkers of Poststroke Upper-Limb Motor Function

BackgroundMotor evoked potentials obtained with transcranial magnetic stimulation (TMS) can provide valuable information to inform stroke neurophysiology and recovery but are difficult to obtain in all stroke survivors due to high stimulation thresholds.ObjectiveTo determine whether transcranial magnetic stimulation evoked potentials (TEPs) evoked using a lower stimulus intensity, below that necessary for recording motor evoked potentials, could serve as a marker of poststroke upper-limb motor function and were different compared to healthy adults.MethodsEight chronic stroke survivors (66 ± 21 years) and 15 healthy adults (53 ± 10 years) performed a motor function task using a customized grip-lift manipulandum. TMS was applied to the lesioned motor cortex, with TEPs recorded using simultaneous high-definition electroencephalography (EEG).ResultsStroke participants demonstrated greater hold ratio with the manipulandum. Cluster-based statistics revealed larger P30 amplitude in stroke participants, with significant clusters over frontal (P = .016) and parietal-occipital electrodes (P = .023). There was a negative correlation between the N45 peak amplitude and hold ratio in stroke participants (r = ?.83, P = .02), but not controls.ConclusionsTEPs can be recorded using lower stimulus intensities in chronic stroke. The global P30 TEP response differed between stroke participants and healthy controls, with results suggesting that the TEP can be used as a biomarker of upper-limb behavior.     

Generalized motor programme and parameterization accuracy in apraxia of speech and conduction aphasia

Abstract

The present study examined three aspects of motor programming (generalized motor programme (GMP) accuracy, temporal parameterization accuracy, and amplitude parameterization accuracy) in subjects with apraxia of speech (AOS) or conduction aphasia (CA) and normal speaking participants. Subjects were presented with a movement pattern on a monitor that they were required to produce with the jaw, after the target pattern had been removed from view. Analyses examined differences in relative (parameterization) and absolute (GMP) timing and amplitude between the target and actual movement. Examination of individual subject performance revealed inter-subject variability within the AOS group, with two of the four subjects demonstrating unimpaired GMP accuracy but poor parameterization accuracy, while the other two subjects exhibited the opposite pattern, impaired GMP accuracy but normal parameterization. No clear pattern of deficit was noted for the subjects with CA. Results are discussed with respect to motor control theories of AOS and CA.     

Ageing affects event-related potentials and brain oscillations: a behavioral and electrophysiological study using a haptic recognition memory task

In this electrophysiological study, we investigated the effects of ageing on recognition memory for three-dimensional (3D) familiar objects presented to touch in a continuous paradigm. To examine changes in event-related potentials (ERPs) and brain oscillations, we recorded the EEGs of healthy groups of young (n = 14; mean age = 32.3 years) and older adults (n = 14; mean age = 65.1). Both age groups exhibited similar accuracy and exploration times when making old–new judgments. Young and older participants showed a marginally significant ERP old/new effect widely distributed over the scalp between 550–750 ms. In addition, the elders showed lower amplitude than younger participants within 1200–1500 ms. There were age-related differences in brain oscillations as measured by event-related spectral perturbation (ERSP). Older adults showed greater alpha and beta power reductions than young participants, suggesting the recruitment of additional neural resources. In contrast, the two age groups showed a reliable old/new effect in the theta band that temporarily overlapped the ERP old/new effect. The present results suggest that despite similar behavioral performance, the young and older adults recruited different neural resources to perform a haptic recognition task.     

Changes in event-related potentials during dual task walking in aging and Parkinson's disease

ObjectiveTo investigate EEG changes during an auditory odd-ball task while walking (dual-task) in young adults, older adults, and patients with Parkinson's disease.Methods11 young adults, 10 older adults, and 10 patients with Parkinson’s disease (PD) performed an auditory oddball task during standing and walking on a treadmill, while wearing a wireless EEG cap. The amplitude and latency of P300 were compared between groups and within conditions using linear mix model analysis. Gait was evaluated using wearable sensors and cognition was assessed using the Color Trail Test.ResultsP300 latency became longer during walking in all groups (p = 0.005). During walking, older adults (p = 0.005) and patients with PD (p = 0.001) showed prolonged P300 latency compared to young adults. Significant task by group interaction was found in P300 amplitude (p = 0.008). Patients with PD demonstrated reduced P300 amplitude during walking compared to standing (p = 0.023). Among all subjects, better motor and cognitive performance correlated with shorter P300 latency (r = 0.457, p = 0.014 and r = 0.431, p = 0.040, respectively).ConclusionsThese findings provide direct evidence of the physiological recruitment of attentional networks during walking and their impact by ageing and disease.SignificanceThis study is the first to report on changes in P300 latency and amplitude during dual-task oddball walking in older adults and patients with PD.     

Psychosocial intervention in at-risk adolescents: using event-related potentials to assess changes in decision making and feedback processing

Decision making and feedback processing are two important cognitive processes that are impacted by social context, particularly during adolescence. The current study examined whether a psychosocial intervention could improve psychological wellbeing in at-risk adolescent boys, thereby improving their decision making and feedback processing skills. Two groups of at-risk adolescents were compared: those who were relatively new to a psychosocial intervention, and those who had engaged over a longer time period. Electroencephalography was recorded while the young people participated in a modified version of the Taylor Aggression Paradigm. The late positive potential (LPP) was measured during the decision phase of the task (where participants selected punishments for their opponents). The feedback-related negativity (FRN) and P3 components were measured during the task’s outcome phase (where participants received ‘win’ or ‘lose’ feedback). Adolescents who were new to the intervention (the minimal-intervention group) were harsher in their punishment selections than those who had been engaged in the program for much longer. The minimal-intervention group also showed an enhanced LPP during the decision phase of the task, which may be indicative of immature decision making in that group. Analysis of the FRN and P3 amplitudes revealed that the minimal-intervention group was physiologically hypo-sensitive to feedback, compared with the extended-intervention group. Overall, these findings suggest that long-term community-based psychosocial intervention programs are beneficial for at-risk adolescents, and that event-related potentials can be employed as biomarkers of therapeutic change. However, because participants were not randomly allocated to treatment groups, alternative explanations cannot be excluded until further randomized controlled trials are undertaken.

     

Increased perseverative errors following high-definition transcranial direct current stimulation over the ventrolateral cortex during probabilistic reversal learning

BackgroundThe prefrontal cortex regulates behavioural adaptation in response to feedback. However, the causal role of different prefrontal regions remains unclear, based on indirect evidence derived from functional neuroimaging. Neuroimaging studies show dorsomedial prefrontal activation during feedback monitoring, whereas the ventrolateral prefrontal cortex engages during behavioural adaptation (shifting).ObjectiveWe used high-definition transcranial direct current stimulation (HD-tDCS) to elucidate the roles of the ventrolateral prefrontal cortex (vlPFC) and the dorsomedial prefrontal cortex (dmPFC) in behaviour change, using a probabilistic reversal learning task (PRLT).MethodFifty-two healthy adults were randomly assigned to receive cathodal HD-tDCS to inhibit the vlPFC or the dmPFC versus sham stimulation, prior to completing the PRLT. The outcome measures were the number of perseverative errors and the electroencephalography (EEG) signals of feedback-related negativity (FRN) in the PRLT. We hypothesised that inhibition of the vlPFC would be specifically associated with more perseverative errors and weaker FRNs.ResultsWe found that vlPFC inhibition was associated with higher perseverative errors compared to sham and dmPFC stimulation conditions. Although there were no statistically significant differences in FRN amplitudes, the effect sizes indicate an association between inhibition of the vlPFC and lower FRN amplitudes.ConclusionOur findings support a causal role of the vlPFC on feedback-based behavioural adaptation, which is critical for adaptive goal-driven behaviour.     

It is less than you expected: The feedback-related negativity reflects violations of reward magnitude expectations

The anterior cingulate cortex (ACC) is involved in performance monitoring and in learning from performance feedback. Recent research suggests that the feedback-related negativity (FRN), an event-related potentials (ERP) component reflecting neural activity in the ACC, codes the size of a negative prediction error when reward probabilities are varied. There is as yet no clear evidence that the FRN is also sensitive to violations of reward magnitude expectations. In the present study, 20 healthy young subjects engaged in a learning task in which a coin had to be found on each trial. The value of the coin (the potential reward magnitude) was varied from trial to trial and amounted to 5 cent, 20 cent or 50 cent. Analysis of ERPs revealed that FRN amplitude differences between reward and non-reward were significantly modulated by (potential) reward magnitude. This effect was driven by the neural response to non-reward: the larger the potential reward, the larger was the FRN amplitude in response to non-reward. In contrast, the P300 was larger for positive outcomes and showed an effect of (potential) reward magnitude independent of valence. Together with evidence from previous studies, these results show that the FRN codes negative prediction errors in the context of varying reward probabilities and magnitudes. The findings are in line with recent results based on functional neuroimaging and lend further support to the idea of a key role of the ACC in the integration of information on different aspects of performance outcomes.     

Feedback and reward processing in high-functioning autism

Individuals with high-functioning autism often display deficits in social interactions and high-level cognitive functions. Such deficits may be influenced by poor ability to process feedback and rewards. The feedback-related negativity (FRN) is an event-related potential (ERP) that is more negative following losses than gains. We examined FRN amplitude in 25 individuals with Autism Spectrum Disorder (ASD) and 25 age- and IQ-matched typically developing control participants who completed a guessing task with monetary loss/gain feedback. Both groups demonstrated a robust FRN that was more negative to loss trials than gain trials; however, groups did not differ in FRN amplitude as a function of gain or loss trials. N1 and P300 amplitudes did not differentiate groups. FRN amplitude was positively correlated with age in individuals with ASD, but not measures of intelligence, anxiety, behavioral inhibition, or autism severity. Given previous findings of reduced-amplitude error-related negativity (ERN) in ASD, we propose that individuals with ASD may process external, concrete, feedback similar to typically developing individuals, but have difficulty with internal, more abstract, regulation of performance.     

Processing of performance errors predicts memory formation: Enhanced feedback‐related negativities for corrected versus repeated errors in an associative learning paradigm

Learning from errors or negative feedback is crucial for adaptive behavior. FMRI studies have demonstrated enhanced anterior cingulate cortex activity for errors that were later corrected versus repeated errors even when a substantial delay between the error and the opportunity to correct was introduced. We aimed at identifying the electrophysiological correlates of these processes by investigating the feedback‐related negativity (FRN) and stimulus‐locked P3. Participants had to learn and recall the location of 2‐digit targets over consecutive rounds. Feedback was provided in two steps, first a color change indicated a correct or incorrect response (feedback phase) followed by presentation of the correct digit information (re‐encoding phase). Behaviorally, participants improved performance from the first to the third round. FRN amplitudes time‐locked to feedback were enhanced for corrected compared to repeated errors. The P3 in response to re‐encoding did not differ between the two error types. The finding that FRN amplitudes positively predicted memory performance is consistent with the idea that the FRN reflects prediction errors and the need for enhanced cognitive control. Interestingly, this happens early during feedback processing and not at a later time point when re‐encoding of correct information takes place. The prediction error signal reflected in the FRN is usually elicited by performance errors, but may thus also play a role in preparing/optimizing the system for memory formation. This supports the existence of a close link between action control and memory processes even when there is a substantial delay between error feedback and the opportunity to correct the error.     

Age-related Differences in Short- and Long-interval Intracortical Inhibition in a Human Hand Muscle

BackgroundEffects of age on the assessment of intracortical inhibition with paired-pulse transcranial magnetic stimulation (TMS) have been variable, which may be due to between-study differences in test TMS intensity and test motor evoked potential (MEP) amplitude.ObjectiveTo investigate age-related differences in short- (SICI) and long-interval intracortical inhibition (LICI) across a range of test TMS intensities and test MEP amplitudes.MethodsIn 22 young and 18 older subjects, SICI and LICI were recorded at a range of test TMS intensities (110%–150% of motor threshold) while the first dorsal interosseous (FDI) muscle was at rest, or producing a precision grip of the index finger and thumb. Data were subsequently compared according to the amplitude of the MEP produced by the test alone TMS.ResultsWhen pooled across all test TMS intensities, SICI in resting muscle and LICI in active muscle were similar in young and older adults, whereas SICI in active muscle and LICI in resting muscle were reduced in older adults. Regrouping data based on test MEP amplitude demonstrated similar effects of age for SICI and LICI in resting muscle, whereas more subtle differences between age groups were revealed for SICI and LICI in active muscle.ConclusionsAdvancing age influences GABA-mediated intracortical inhibition, but the outcome is dependent on the experimental conditions. Age-related differences in SICI and LICI were influenced by test TMS intensity and test MEP amplitude, suggesting that these are important considerations when assessing intracortical inhibition in older adults, particularly in an active muscle.     

An exchange of letters

The study examined possible methods for improving the performance of older eyewitnesses on identification line-ups. Young and old adults viewed a simulated crime event involving a young and old perpetrator, and were subsequently asked to identify these two perpetrators from line-ups that were either target present (TP) or target absent (TA). Research conducted by the present authors indicates that older adults have significant problems with remembering instructions informing them that the perpetrator may or may not be present in the line-up and this may contribute to the age deficit in line-up performance. Therefore, in the present study, prior to the line-ups, half the participants received enhanced non-biased line-up instructions. Furthermore, the performance age deficit demonstrated by older adults in previous relevant studies is largely characterised by an increase in false identifications. The sequential line-up is known to reduce false identifications. Therefore, half the participants viewed line-ups that were presented sequentially and half viewed line-ups that were presented simultaneously. Older participants were found overall to demonstrate poorer line-up performance compared to younger participants. Though enhanced line-up instructions led to significantly better memory concerning the possibility the perpetrator may or may not be present in the line-up, they had no significant effect on line-up performance. Line-up presentation (sequential vs. simultaneous) had differential effects across conditions, with sequential presentation not always being beneficial.     

Long-Term Safety and Efficacy of Deutetrabenazine in Younger and Older Patients With Tardive Dyskinesia

ObjectivesTo assess long-term safety and efficacy of deutetrabenazine in younger (<55 years) and older (≥55 years) adult participants with tardive dyskinesia (TD).DesignThree-year, single-arm, open-label extension (OLE) study enrolling participants who completed the 12-week, pivotal ARM-TD or AIM-TD studies.SettingSeventy-six centers in the United States and Europe.ParticipantsA total of 337 participants with TD (119 younger and 218 older).InterventionDeutetrabenazine was initiated at 12 mg/day and titrated once weekly by 6 mg/day using a response-driven dosing regimen until adequate dyskinesia control was reached or a clinically significant adverse event occurred.MeasurementsThis post hoc analysis assessed change and percent change from baseline in total motor Abnormal Involuntary Movement Scale (AIMS) score, response rates for ≥50% AIMS improvement, Clinical Global Impression of Change (CGIC), Patient Global Impression of Change (PGIC), and safety in younger and older participants with TD.ResultsAfter 3 years of open-label treatment, mean deutetrabenazine dose was ～39.5 mg/day in both groups. Mean±SE changes from baseline in total motor AIMS score were –6.7 ± 0.62 and –6.5 ± 0.47 in younger and older participants, respectively (percent changes: –61.4% ± 4.10% and –54.6% ± 3.01%); 76% of younger and 62% of older participants achieved ≥50% AIMS response. Most younger and older participants achieved treatment success per CGIC (67% and 76%) and PGIC (64% and 63%). Deutetrabenazine was generally well tolerated in both groups.ConclusionsDeutetrabenazine treatment was associated with sustained improvements in total motor AIMS score, treatment success, and improved quality of life, and was well tolerated in younger and older adults with TD in this 3-year OLE study.     

Neural correlates of movement preparation in healthy ageing

Motor disorders increase dramatically with age; however, little is known about non-clinical ageing of motor control mechanisms and their respective neural correlates. With the present experiment we aimed to study age effects on advance movement preparation, a key characteristic of motor behaviour that is known to involve premotor and primary motor circuits. The respective brain regions are subject to age-related brain atrophy of grey and white matter, and we therefore hypothesized that motor preparation mechanisms may be altered in older persons.
Using a motor priming paradigm, performance data and event-related potentials were recorded in older (68–83 years) and younger (21–25 years) participants. The effect pattern observed for the younger group fully replicated previous findings, showing significant reaction time benefits and greater foreperiod activity for valid trials, as well as lateralized activation over motor regions. In older participants, the validity effect was insignificant, which corresponded to markedly reduced foreperiod amplitudes and the absence of lateralized activity. At the same time, the event-related potential showed a frontocentrally distributed positive component peaking in the P300 latency range after presentation of the prime. The amplitude of this potential was enhanced in elderly compared with young participants.
The data suggest that the information processing related to the anticipation and preparation of an upcoming response changes substantially with age. In contrast to younger participants, older participants show no indication of effector-specific activation and recruit frontal areas in anticipation of a response signal. It is therefore not only movement execution that changes with age but also motor cognition.     

AGING,CONTEXT MEMORY AND BINDING: A COMPARISON OF “WHAT,WHERE AND WHEN” IN YOUNG AND OLDER ADULTS

There is evidence that age-related memory decline does not effect all types of episodic information to an equal extent, but that especially contextual memory and the integration of multiple features in memory deteriorate. The current study investigates contextual memory in a group of healthy young (N = 40) and older (N = 40) adults without dementia. All participants performed a computerized memory task assessing target memory (objects only), contextual memory (positions only) and memory for the combinations of two features (object, space, temporal order), that is, binding of target-context or context-context features. The results showed age-related decline on all task conditions. Furthermore, the performance on conditions requiring the binding of target and context features was affected to a greater extent in older adults compared to younger adults. These findings support the notion that a decline in contextual memory and binding might underlie poorer episodic memory in older participants.     

Inter-trial coherence of medial frontal theta oscillations linked to differential feedback processing in youth and young adults with autism

BackgroundImpairment in prediction and appreciation for choice outcomes could contribute to several core symptoms of ASD. We examined electroencephalography (EEG) oscillations in 27 youth and young adults diagnosed with autism spectrum disorder (ASD) and 22 IQ-matched neurotypical controls while they performed a chance-based reward prediction task.MethodWe re-analyzed our previously published ERP data (Larson et al., 2011) and examined theta band oscillations (4–8 Hz) at frontal midline sites, within a timing window that overlaps with the feedback-related negativity (FRN). We focused on event-related changes after presentation of feedback for reward (WIN) and punitive (LOSE) outcomes, both for spectral power and inter-trial phase coherence.ResultsIn our reward prediction task, for both groups, medial frontal theta power and phase coherence were greater following LOSE compared to WIN feedback. However, compared to controls, inter-trial coherence of medial frontal theta was significantly lower overall (across both feedback types) for individuals with ASD. Our results indicate that while individuals with ASD are sensitive to the valence of reward feedback, comparable to their neurotypical peers, they have reduced synchronization of medial frontal theta activity during feedback processing.ConclusionsThis finding is consistent with previous studies showing neural variability in ASD and suggest that the processes underlying decision-making and reinforcement learning may be atypical and less efficient in ASD.