Javier García-Pacios

Early detection and late cognitive control of emotional distraction by the prefrontal cortex

Unpleasant emotional distraction can impair the retention of non-emotional information in working memory (WM). Research links the prefrontal cortex with the successful control of such biologically relevant distractors, although the temporal changes in this brain mechanism remain unexplored. We use magnetoencephalography to investigate the temporal dynamics of the cognitive control of both unpleasant and pleasant distraction, in the millisecond (ms) scale. Behavioral results demonstrate that pleasant events do not affect WM maintenance more than neutral ones. Neuroimaging results show that prefrontal cortices are recruited for the rapid detection of emotional distraction, at early latencies of the processing (70-130 ms). Later in the processing (360-450 ms), the dorsolateral, the medial and the orbital sections of the prefrontal cortex mediate the effective control of emotional distraction. In accordance with the behavioral performance, pleasant distractors do not require higher prefrontal activity than neutral ones. These findings extend our knowledge about the brain mechanisms of coping with emotional distraction in WM. In particular, they show for the first time that overriding the attentional capture triggered by emotional distractors, while maintaining task-relevant elements in mind, is based on the early detection of such linked-to-survival information and on its later cognitive control by the prefrontal cortex.

Efficiency at rest: magnetoencephalographic resting-state connectivity and individual differences in verbal working memory.

Inter-individual differences in cognitive performance are based on an efficient use of task-related brain resources. However, little is known yet on how these differences might be reflected on resting-state brain networks. Here we used Magnetoencephalography resting-state recordings to assess the relationship between a behavioral measurement of verbal working memory and functional connectivity as measured through Mutual Information. We studied theta (4-8 Hz), low alpha (8-10 Hz), high alpha (10-13 Hz), low beta (13-18 Hz) and high beta (18-30 Hz) frequency bands. A higher verbal working memory capacity was associated with a lower mutual information in the low alpha band, prominently among right-anterior and left-lateral sensors. The results suggest that an efficient brain organization in the domain of verbal working memory might be related to a lower resting-state functional connectivity across large-scale brain networks possibly involving right prefrontal and left perisylvian areas.

Early Prefrontal Activation As a Mechanism to Prevent Forgetting in the Context of Interference

OBJECTIVE Recent research has focused on interference resolution deficits as the main cause of short-term memory decreases in aging. To determine whether activation of brain compensatory mechanisms occur during the encoding process in older people. Moreover, two different levels of interference (distraction and interruption) were presented during the maintenance period to examine how they modulate brain activity profiles. DESIGN A delayed match-to-sample task with two experimental conditions: distraction and interruption. PARTICIPANTS Twenty-seven young adults from Complutense University of Madrid and 20 healthy older adults from Complutense Elderly University of Madrid. MEASUREMENTS Magnetoencephalography scans were recorded during the execution of a working memory interference task. Brain activity sources from younger and older adults during the encoding stage were compared in each condition using minimum norm estimation analyses. RESULTS The elderly showed enhancement of prefrontal activity during early latencies of the encoding process in both conditions. In the distraction condition, enhanced activity was located in left ventrolateral prefrontal regions, whereas in the interruption condition, enhanced activity was observed in the right ventral prefrontal areas and anterior cingulate cortex. CONCLUSION Increased recruitment of prefrontal regions in the elderly might be related to the processing depth of information, encoding of new information and semantic associations that are successfully recalled, and with interference resolution and preparatory control when the level of interference becomes higher. These prefrontal modulations during early latencies might reflect a higher top-down control of the encoding process in normal aging to prevent forgetting.

Tracking the effect of emotional distraction in working memory brain networks: Evidence from an MEG study

The active maintenance of information in visual working memory (WM) is known to rely on the sustained activity over functional networks including frontal, parietal, occipital, and temporal cortices. Previous studies have described interference-based disturbances in the functional coupling between prefrontal and posterior cortices, and that such disturbances can be restored for a successful WM performance after the presentation of the interfering stimulus. However, very few studies have applied functional connectivity measures to the analysis of the brain dynamics involved in overriding emotional distraction, and all of them have limited their analysis to the particular connections between the amygdala and prefrontal cortex. In this study, we used magnetoencephalography (MEG) to characterize the mutual information-based functional connectivity dynamics among regions of interest located over the prefrontal, the parietal, the temporal, and the occipital cortex. Our results show that the detection of emotional distraction at early latencies (50-150 ms) induces a reduction of functional connectivity involving parietal and temporal cortices that are part of the frontoposterior WM network, while functional coupling among prefrontal areas and between them and posterior cortices is strengthened during the detection of emotional distractors. Later in the processing of the distractor (250-350 and 360-460 ms), the frontoposterior coupling is reestablished for a successful performance, while the orbitofrontal and ventrolateral prefrontal cortex become strongly connected to posterior cortices as a mechanism to cope with emotional distractors.

Emotional interference-based forgetting in short-term memory. Cognitive inhibition of pleasant but not unpleasant biologically relevant distractors.

Emotional stimuli automatically recruit attentional resources. Although this usually brings more adaptive responses, it may suppose a disadvantage when emotional information is task-irrelevant and should be ignored. Previous studies have shown how emotional stimuli with a negative content exert a greater interference than neutral stimuli during a concurrent working memory (WM) task. However, the impact of positively valenced stimuli as interference has not been addressed to date. In three experiments and one re-analysis we explore the impact of pleasant and unpleasant emotional distractors during WM maintenance. The results suggest that our cognitive control can cope with the interference posed by pleasant distractors as well as with the interference posed by neutral stimuli. However, unpleasant distractors are harder to control in the context of WM maintenance. As unpleasant stimuli usually convey relevant information that we should not to ignore, our executive control seems to be less able to reallocate cognitive resources after unpleasant distraction.

Interference Impacts Working Memory in Mild Cognitive Impairment

Mild cognitive impairment (MCI) is considered a transitional stage between healthy aging and dementia, specifically Alzheimers disease (AD). The most common cognitive impairment of MCI includes episodic memory loss and difficulties in working memory (WM). Interference can deplete WM, and an optimal WM performance requires an effective control of attentional resources between the memoranda and the incoming stimuli. Difficulties in handling interference lead to forgetting. However, the interplay between interference and WM in MCI is not well-understood and needs further investigation. The current study investigated the effect of interference during a WM task in 20 MCIs and 20 healthy elder volunteers. Participants performed a delayed match-to-sample paradigm which consisted in two interference conditions, distraction and interruption, and one control condition without any interference. Results evidenced a disproportionate impact of interference on the WM performance of MCIs, mainly in the presence of interruption. These findings demonstrate that interference, and more precisely interruption, is an important proxy for memory-related deficits in MCI. Thus, the current findings reveal novel evidence regarding the causes of WM forgetting in MCI patients, associated with difficulties in the mechanisms of attentional control.

Efficacy of an intervention programme for rehabilitation of awareness of deficit after acquired brain injury: A pilot study

ABSTRACT Background: Impaired Awareness of Deficit (AD) is a frequent symptom after suffering acquired brain injury (ABI) that severely influences patients’ daily lives. Primary Objective: Pilot study to assess the effectiveness of a structured intervention programme which was developed from a biopsychosocial approach, and relied on common therapeutic strategies of proven effectiveness. Methods: We assessed the effectiveness of our intervention on a sample of 60 patients with ABI, 30 of whom received the specific AD intervention programme, while the other 30 followed an equivalent rehabilitation approach where they received no specific intervention on AD. AD were assessed before and after the specific intervention on AD through an ad-hoc designed questionnaire. Results: This study reports that patients who received the proposed programme demonstrated significant improvement in their level of AD, as compared to the control group. This improvement was observable on all the proposed dimensions of awareness. Interestingly, results from correlation analysis also showed that patients with lower initial AD were those who exhibited a greater degree of improvement following the intervention. Conclusions: This research provides evidence in favour of the effectiveness of implementing an intervention programme for AD in the context a global rehabilitation process for patients with ABI.

Dynamics of cortical language plasticity by means of magnetoencephalography

We present a review of recent advances in the functional study of cortical language reorganization by means of magnetoencephalography (MEG). Initially we review some basic concepts on biomagnetism, necessary to understand the characteristics distinguishing MEG from others functional neuroimaging tools, namely: a high temporal resolution, an acceptable spatial resolution, no need of reference and a non-invasive method to collect brain activity. The main research for validation of MEG language mapping is reviewed, comparing its ability with other techniques such as Wada test or electric cortical stimulation. We also examine several studies on atypical language neural representation without brain damage. Finally, we reveal recent advances regarding neural correlates for developmental dyslexia and recovery of language skills after many types of brain damage. Taking into account its particular features, MEG can provide a new and revealing approach to the study of plastic changes in the fronto-temporo-parietal cortical network, which sustains language processing.