Shulan Hsieh

Neurofeedback training improves attention and working memory performance

OBJECTIVES The present study aimed to investigate the effectiveness of the frontal-midline theta (fmθ) activity uptraining protocol on attention and working memory performance of older and younger participants. METHODS Thirty-two participants were recruited. Participants within each age group were randomly assigned to either the neurofeedback training (fmθ uptraining) group or the sham-neurofeedback training group. RESULTS There was a significant improvement in orienting scores in the older neurofeedback training group. In addition, there was a significant improvement in conflict scores in both the older and young neurofeedback training groups. However, alerting scores failed to increase. In addition, the fmθ training was found to improve working memory function in the older participants. The results further showed that fmθ training can modulate resting EEG for both neurofeedback groups. CONCLUSIONS Our study demonstrated that fmθ uptraining improved attention and working memory performance and theta activity in the resting state for normal aging adults. In addition, younger participants also benefited from the present protocol in terms of improving their executive function. SIGNIFICANCE The current findings contribute to a better understanding of the mechanisms underlying neurofeedback training in cognitive function, and suggest that the fmθ uptraining protocol is an effective intervention program for cognitive aging.

Classifying different emotional states by means of EEG-based functional connectivity patterns.

This study aimed to classify different emotional states by means of EEG-based functional connectivity patterns. Forty young participants viewed film clips that evoked the following emotional states: neutral, positive, or negative. Three connectivity indices, including correlation, coherence, and phase synchronization, were used to estimate brain functional connectivity in EEG signals. Following each film clip, participants were asked to report on their subjective affect. The results indicated that the EEG-based functional connectivity change was significantly different among emotional states. Furthermore, the connectivity pattern was detected by pattern classification analysis using Quadratic Discriminant Analysis. The results indicated that the classification rate was better than chance. We conclude that estimating EEG-based functional connectivity provides a useful tool for studying the relationship between brain activity and emotional states.

Loving-kindness brings loving-kindness: The impact of Buddhism on cognitive self-other integration

Common wisdom has it that Buddhism enhances compassion and self–other integration. We put this assumption to empirical test by comparing practicing Taiwanese Buddhists with well-matched atheists. Buddhists showed more evidence of self–other integration in the social Simon task, which assesses the degree to which people co-represent the actions of a coactor. This suggests that self–other integration and task co-representation vary as a function of religious practice.

Left visual-field advantage in the dual-stream RSVP task and reading-direction: A study in three nations

In the dual-stream Rapid Serial Visual Presentation task, a stream of stimuli containing two target stimuli is rapidly presented left and right. In previous studies, the second target was better identified in the left than in the right hemifield. In all those studies, alphanumeric stimuli were used both as targets and distracters. We examined to what extent this left visual-field advantage is dependent on reading-direction. The task was performed by Germans (with Latin characters), Israelis (with Latin and Hebrew characters) and Taiwanese (with Latin and Chinese characters). If caused by overlearnt associative links between Latin characters and left-to-right reading, the prominent left visual-field bias should be reversed in Hebrew and disappear in Chinese. Furthermore, if caused by direction of reading in the participants native language, the left visual-field advantage in Latin conditions should be larger in Germans than in Israelis and Taiwanese. A left visual-field advantage was always observed, though slightly smaller in Hebrew and in Chinese, and there was no difference in the Latin conditions between the three nations. Therefore, it seems that the left visual-field advantage in speeded target identification is not primarily caused by the left-to-right reading-direction, but may be a combined effect resulting from the asymmetric organization of general mechanisms of visual processing and from stimulus-induced preferences.

Immediate error correction process following sleep deprivation

Previous studies have suggested that one night of sleep deprivation decreases frontal lobe metabolic activity, particularly in the anterior cingulated cortex (ACC), resulting in decreased performance in various executive function tasks. This study thus attempted to address whether sleep deprivation impaired the executive function of error detection and error correction. Sixteen young healthy college students (seven women, nine men, with ages ranging from 18 to 23 years) participated in this study. Participants performed a modified letter flanker task and were instructed to make immediate error corrections on detecting performance errors. Event‐related potentials (ERPs) during the flanker task were obtained using a within‐subject, repeated‐measure design. The error negativity or error‐related negativity (Ne/ERN) and the error positivity (Pe) seen immediately after errors were analyzed. The results show that the amplitude of the Ne/ERN was reduced significantly following sleep deprivation. Reduction also occurred for error trials with subsequent correction, indicating that sleep deprivation influenced error correction ability. This study further demonstrated that the impairment in immediate error correction following sleep deprivation was confined to specific stimulus types, with both Ne/ERN and behavioral correction rates being reduced only for trials in which flanker stimuli were incongruent with the target stimulus, while the response to the target was compatible with that of the flanker stimuli following sleep deprivation. The results thus warrant future systematic investigation of the interaction between stimulus type and error correction following sleep deprivation.

Task reconfiguration and carryover in task switching: An event-related potential study

This study investigated the electrophysiological correlates of the processes involved in task switching. A pair-wise task-switching paradigm was used where each trial comprised two tasks that were either the same (task repeat) or different (task switch). In the paradigm, task-switch and repeat trials are compared in conditions of foreknowledge and non-foreknowledge of the forthcoming task type and during different response-stimulus intervals (RSIs). The results of this study show that, before the second task began in a task-pair trial, i.e., during the RSI, there was a CNV-like negativity for all trials. This indicates a general anticipatory effect. In foreknowledge conditions, there is an additional switch-specific reconfiguration process followed by a task-specific (including both switch- and repeat-related) preparatory process. During the post-task 2 stage, P3b was found to be smaller in switch trials than in repeat trials. Such differential P3b between switch and repeat trials appeared earlier and larger in foreknowledge than in non-foreknowledge conditions. The results of this study support the existence of advance preparation and uphold the role of carryover effects in task switching.

Switching between simple response-sets: inferences from the lateralized readiness potential.

Behavioral studies have documented that task switching incurs a longer reaction time than task repetition, and that advance cueing information about the forthcoming task reduces mean reaction time. The present study used P300 peak latency and two lateralized readiness potential (LRP) intervals--stimulus-locked and response-locked--to infer the loci of task switch and task-cueing effects and how they may interact in the basic task processing chain. Participants performed two tasks in a random order, so that on each trial they either repeated the task from the previous trial or switched to another task. In one condition, each stimulus was preceded by a cue informing participants which of the two tasks to perform; and in the other condition, each stimulus was preceded by a non-informative cue. Results indicated that both mean reaction times and the stimulus-locked LRP intervals were longer for switch than repeated trials, whereas P300 peak latencies and response-locked LRP intervals were identical for both trials. Similarly, both reaction times and the stimulus-locked LRP intervals were longer for no task-cueing than for task-cueing conditions, and P300 peak latencies and the response-locked LRP intervals were identical for both conditions. Finally, task switch and task-cueing effects appeared to be approximately additive, indicating the two factors influence distinct stage processes. We suggest that task switching resulted in prolongation of the response selection process by carry-over priming effects from the previous task, whereas task-cueing shortened the duration of the earlier process before response selection on both switch and repeated trials.

Resolving Task Rule Incongruence During Task Switching by Competitor Rule Suppression

Task switching requires maintaining readiness to execute any task of a given set of tasks. However, when tasks switch, the readiness to execute the now-irrelevant task generates interference, as seen in the task rule incongruence effect. Overcoming such interference requires fine-tuned inhibition that impairs task readiness only minimally. In an experiment involving 2 object classification tasks and 2 location classification tasks, the authors show that irrelevant task rules that generate response conflicts are inhibited. This competitor rule suppression (CRS) is seen in response slowing in subsequent trials, when the competing rules become relevant. CRS is shown to operate on specific rules without affecting similar rules. CRS and backward inhibition, which is another inhibitory phenomenon, produced additive effects on reaction time, suggesting their mutual independence. Implications for current formal theories of task switching as well as for conflict monitoring theories are discussed.

Elderly adults through compensatory responses can be just as capable as young adults in inhibiting the flanker influence

The goals of this study were to determine whether there is an age-related flanker effect, whether elderly adults produce compensatory responses to overcome their deficiencies, and the extent to which any compensatory responses vary depending on the degree of task demands. To achieve these goals, we manipulated different degrees of demands in cognitive control in a flanker-task paradigm, such as by arranging different proportions of trials in which either a compatible or an incompatible response with respect to the targets pointing direction was required. Throughout the three experiments, we did not observe an increased flanker effect on behavioral measures exhibited by elderly adults compared with young adults. However, several compensatory responses by elderly adults were observed, as evident by the results of event-related potential components. Furthermore, these age-related compensatory responses did not vary as a function of different degrees of task demands. The results suggest that, through the use of compensatory responses, elderly adults are just as capable as young adults in inhibiting flanker influence.

Do age-related changes contribute to the flanker effect?

OBJECTIVES The present study examined age-related changes in the flanker effect and the extent to which age interacts with flanker-induced differences in perceptual processing, which contribute to the flanker effect. METHODS We adopted a modified flanker-task paradigm that incorporates PRO (i.e., hand responses correspond to target arrows) and ANTI (i.e., hand responses do not correspond to target arrows) conditions. Participants from two age groups searched for a centrally presented target flanked on each side by stimuli that were associated with either the same response as the target (congruent), the opposite response (incongruent), or neither response (neutral). Event-related potentials (ERPs), lateralized readiness potentials (LRPs), and behavioral performance were measured. RESULTS The behavioral-data results showed that a typical flanker effect was present in both age groups in PRO and ANTI conditions, suggesting that flanker-induced differences in perceptual processing contributed to the flanker effect in a similar manner for both age groups. Furthermore, no increase in flanker interference was observed in older adults. LRP profiles also provided convergent evidence showing that perceptually based flanker effects were similar for both age groups. CONCLUSIONS The present study suggests that aging does not increase flanker interference, nor does it alter perceptually based flanker interference. SIGNIFICANCE The present study found that older adults could be just as capable as younger adults in resolving flanker interference by adopting different strategies to compensate for their deficiencies.