Human recognition memory and conflict control: An event-related potential study

Attention control training and transfer effects on cognitive tasks

Attention control is the common element underlying different executive functions. The backward Masking Majority Function Task (MFT-M) requires intensive attention control, and represents a diverse situation where attentional resources need to be allocated dynamically and flexibly to reduce uncertainty. Aiming to train attention control using MFT-M and examine the training transfer effects in various executive functions, we recruited healthy young adults (n = 84) and then equally randomized them into two groups trained with either MFT-M or a sham program for seven consecutive days. Cognitive evaluations were conducted before and after the training, and the electroencephalograph (EEG) signals were recorded for the revised Attention Network Test (ANT-R), N-back, and Task-switching (TS) tasks. Compared to the control group, the training group performed better on the congruent condition of Flanker and the double-congruency condition of Flanker and Location in the ANT-R task, and on the learning trials in the verbal memory test. The training group also showed a larger P2 amplitude decrease and P3 amplitude increase in the 2-back task and a larger P3 amplitude increase in the TS task's repeat condition than the control group, indicating improved neural efficiency in two tasks' attentional processes. Introversion moderated the transfer effects of training, as indicated by the significant group*introversion interactions on the post-training 1-back efficiency and TS switching cost. Our results suggested that attention control training with the MFT-M showed a broad transfer scope, and the transfer effect was influenced by the form of training task. Introversion facilitated the transfer to working memory and hindered the transfer to flexibility.

The Inhibitory Effect of Emotional Conflict Control on Memory Retrieval

Evidence is mounting that emotional conflict is mainly resolved by the rostral anterior cingulate inhibiting the processing of emotional distractors. However, this theory has not been verified from the perspective of memory retrieval. This experiment aimed to explore the offline effect of emotional conflict processing on memory retrieval. We adopted a modified encoding-retrieval paradigm to explore this issue. Participants' electroencephalography (EEG) signal were also collected. A face-word Stroop task was used to create the congruency factor. In addition, an old/new judgment task was used to evaluate the recognition performance. During the retrieval phase, the response time of the incongruent condition was longer and the recognition accuracy was lower compared with congruent and neutral conditions in the behavioral data. For event-related potentials (ERP), we detected two well-established old/new effects related to memory retrieval under both neutral and emotional conditions: the frontal negativity (FN400) related to familiarity-driven recognition and the late posterior negativity (LPN) related to reconstructive processing or evaluation of retrieval outcomes. More importantly, the old/new effects were missing for incongruent condition during the early stage of FN400 (300-400 ms). Besides, for LPN (700-900 ms), the old/new effects of the incongruent condition are greater than the congruent condition. The results prove that the encoding phase's emotional congruency factor has a regulatory effect on the retrieval phase's early familiarity processing and evaluation of retrieval outcomes. Our data confirm the inhibitory effect of emotional conflict control on memory retrieval and support the emotional conflict control mechanism found in previous studies.

The Role of Emotional Valence for the Processing of Facial and Verbal Stimuli-Positivity or Negativity Bias?

Emotional valence is predominately conveyed in social interactions by words and facial expressions. The existence of broad biases which favor more efficient processing of positive or negative emotions is still a controversial matter. While so far this question has been investigated separately for each modality, in this narrative review of the literature we focus on valence effects in processing both words and facial expressions. In order to identify the factors underlying positivity and negativity effects, and to uncover whether these effects depend on modality and age, we present and analyze three representative overviews of the literature concerning valence effects in word processing, face processing, and combinations of word and face processing. Our analysis of word processing studies points to a positivity bias or a balanced processing of positive and negative words, whereas the analysis of face processing studies showed the existence of separate positivity and negativity biases depending on the experimental paradigm. The mixed results seem to be a product of the different methods and types of stimuli being used. Interestingly, we found that children exhibit a clear positivity advantage for both word and face processing, indicating similar processing biases in both modalities. Over the course of development, the initial positivity advantage gradually disappears, and in some face processing studies even reverses into a negativity bias. We therefore conclude that there is a need for future research that systematically analyses the impact of age and modality on the emergence of these valence effects. Finally, we discuss possible explanations for the presence of the early positivity advantage and its subsequent decrease.

Combination of acupuncture and Chinese herbal formula for elderly adults with mild cognitive impairment: protocol for a randomized controlled trial

Background

Mild cognitive impairment (MCI) is known as a transitional status between normal cognitive function and Alzheimer’s disease (AD). Acupuncture and Chinese herbal medicines (CHMs) are considered to be beneficial to patients with cognitive impairment. However, it is still unknown whether the combination of the two therapies could optimize the therapeutic effect for MCI. This trial is aimed to evaluate the therapeutic effects of acupuncture and the herbal formula Yishen Granule (YSG) for elderly patients with MCI.

Methods/design

This is a multi-sited, patient-blinded, randomized controlled trial (RCT). Two hundred and forty eligible patients will be randomly divided into four groups: A. acupuncture with YSG, B. acupuncture with placebo herbal medicine, C. sham acupuncture with YSG or D. sham acupuncture with placebo herbal medicine. Acupuncture treatment will be given twice a week for 8 weeks and then once a week for 4 weeks. The herbal treatment patients will be given granules daily for 12 weeks, 8 weeks of standard-dose followed by 4 weeks of mid-dose. The primary outcome is scored by the Montreal Cognitive Assessment (MoCA). The secondary outcomes will be scored by the Mini-Mental State Examination (MMSE) and event-related potential (ERP). All the assessments will be conducted at baseline, and at the eighth and 12th week after intervention starts. The follow-up assessments will be performed with the MoCA in the 12th, 24th, and 36th weeks after intervention ends. Intention-to-treat (ITT) analysis will be used in this RCT.

Discussion

This RCT will provide us information on the effect of treating MCI patients with only acupuncture, herbal formula as well as the combination of both. The additive effect or synergistic effect of acupuncture and Chinese herbal formula will then be analyzed.

Trial registration

This trial is registered with ChiCTR-INR-17011569 on 5 June 2017, and has been approved by the Ethics Committee of Shanghai Municipal Hospital of Traditional Chinese Medicine (2017SHL-KY-05).

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3212-z) contains supplementary material, which is available to authorized users.

Green tea supplementation produces better neuroprotective effects than red and black tea in Alzheimer-like rat model

Green tea from Camellia sinensis plays a neuroprotective role in different neurodegenerative conditions, such as memory deficits in Alzheimer disease (AD). However, whether other teas from Camellia sinensis present similar neuroprotective effect still is not clear. Here we investigate effects of green, red and black tea supplementation on memory and hippocampus oxidative status in a rat model of Alzheimer-like disease (AD-like).

METHOD

Wistar male rats were supplemented with green, red or black tea during 8weeks before Aβ intra-hippocampal injection (2μL of Aβ-25-35, CA1 region). AD and sham rats were submitted to memory tests. After euthanasia, oxidative status in the bilateral hippocampus was quantified. Green and red teas avoid memory deficits in AD rats, but only green tea also avoids oxidative stress and damage in the hippocampus. Green tea was more effective for neuroprotection than red and black teas from the Camellia sinensis in the AD rat model.