Neural evidence for advantaged representation of first items in memory

Visual areas activated during perception can retain specific information held in memory without the presence of physical stimuli via distributed activity patterns. Neuroimaging studies have shown that the delay-period representation of information in visual areas is modulated by factors such as memory load and task demands, raising the possibility of serial position as another potential modulator. Specifically, enhanced representation of first items during the post-encoding delay period may serve as a mechanism underlying the well-established but not well-understood primacy effect - the mnemonic advantage of first items. To test this hypothesis, 13 males and 16 females performed a human fMRI task, wherein each trial consisted of the sequential encoding of two stimuli (a famous face and landscape, order counterbalanced), followed by a distracting task, a delay period, and then a cued recall of one of the items. Participants exhibited the expected behavioral primacy effect, manifested as faster recall of the first items. In order to elucidate the still debated neural underpinnings of this effect, using multivariate decoding, a classifier was trained on data collected during encoding to differentiate stimulus categories (i.e., faces vs. landscapes) and tested on data collected during the post-encoding period. Greater reactivation of first versus second items was observed in the ventral occipito-temporal cortex during the entire post-encoding period but not during encoding. Moreover, trial-level analyses revealed that the degree of first-item neural advantage during the post-encoding delay predicted the behavioral primacy effect. These findings highlight the role of item reinstatement in ventral occipito-temporal cortex in the primacy effect and are discussed in the context of the uniqueness of the very first item and event boundaries, illuminating putative neural mechanisms underlying the effect.

A new perspective on the role of the frontoparietal regions in Stroop-like conflicts

Humans are goal-directed; however, goal-unrelated information still affects us, but how? The Stroop task is often used to answer this question, relying on conflict (incongruency) between attributes, one targeted by the task and another irrelevant to the task. The frontal regions of the brain are known to play a crucial role in processing such conflict, as they show increased activity when we encounter incongruent stimuli. Notably, the Stroop stimuli also consist of conceptual dimensions, such as semantic or emotional content, that are independent of the attributes that define the conflict. Since the non-targeted attribute usually refers to the same conceptual dimension as the targeted-attribute, it is relevant to the task at hand. For example, when naming the emotion of an emotional face superimposed by an emotional word, both the targeted-attribute and the non-targeted attribute refer to the conceptual dimension "emotion". We designed an fMRI paradigm to investigate how conflicts between different conceptual dimensions impact us. Even though the conflict was task-irrelevant, incongruent stimuli resulted in longer reaction times, indicating a behavioral congruency effect. When examining the neural mechanisms that underlie this effect, we found that the frontal regions exhibited repetition suppression, while the bilateral intraparietal sulcus (IPS) showed a congruency effect linked to the behavioral effect. Taken together, these findings suggest that individuals are unable to completely ignore task-irrelevant information, and that the IPS plays a crucial role in processing such information.

The First Word Recalled Measure - A Potential Addition to Clinical Exams

Characterizing episodic memory abilities is highly important in the diagnosis of Alzheimer's disease (AD) and mild cognitive impairment (MCI), and usually includes wordlist learning and recall tasks. Clinical evaluations typically focus on the number of words recalled, ignoring additional information, like serial position. Here, we tested the potential value of two serial positioning measures for clinical diagnosis – how retrieval is initiated, as measured by the first word recalled, and how it proceeds – using data from patients with AD and MCI that completed a wordlist learning and recall task. Our results show that during the early stages of learning, patients with AD are less prone to retrieve the first word from the wordlist, manifested as lower primacy effect in the first word recalled, compared with MCI patients. The first word recalled measure adds to the differentiation between the groups over and above the total number of words learned. Thus, the first word recalled during word list learning and recall tasks may be used as a simple complementary measure to distinguish between MCI and AD during standard neuropsychological evaluations.

Is the Cutoff of the MoCA too High? Longitudinal Data From Highly Educated Older Adults

BACKGROUND

The Montreal Cognitive Assessment (MoCA) is widely used to evaluate cognitive decline in older individuals. Although, age and education-related norms have been published, the vast majority of diagnostic clinicians use the MoCA cutoff score to identify patients with cognitive impairment.

AIM

To identify whether the MoCA cutoff is too stringent for cognitively normal older adults.

METHODS

Twenty-seven participants aged 68 to 83 (mean = 75.07, standard deviation [SD] = 4.62), with high education level (mean = 17.14 years, SD = 3.21) underwent cognitive assessment once a year for 5 consecutive years. The cognitive assessment included MoCA; Rey Auditory Verbal Learning Test; Rey Osterrieth Complex Figure test; Wechsler Adult Intelligence Scale Information and Digit Span Subtest; Trail Making Test; Verbal Fluency Test; and Beck Depression Inventory questionnaire. Repeated measures analysis of variance (ANOVA) was used to analyze all standardized scores as well as MoCA standardized and raw scores across all years.

RESULTS

Repeated-measures ANOVA for MoCA raw scores yielded significant decline across the years (P < .05). From the second year and forward, the average MoCA total score was below the cutoff of 26/30. However, in substantial contrast, all other neuropsychological scores and the MoCA standardized scores were within the normal range and even above in all years.

CONCLUSION

Our study demonstrates that the currently used MoCA cutoff is too high even for highly educated, cognitively normal older adults. Therefore, it is crucial to use the age- and education-related norms for the MoCA in order to avoid misdiagnosis of cognitive decline.

Changes in Resting-State Functional Connectivity of the Hippocampus Following Cognitive Effort Predict Memory Decline at Older Age-A Longitudinal fMRI Study

Memory decline is a feature of some, but not all, healthy older adults. The neural patterns of this variability are still largely unknown. We examined the resting-state functional connectivity (RSFC) of older and younger adults before and after cognitive effort as an underlying feature for subsequent memory changes, focusing on the RSFC between the left anterior hippocampus (laHC) and the posterior hippocampi (pHC). Results showed that for younger adults, post-effort increases in laHC–pHC RSFC were related to increases in RSFC between the laHC and the hubs of the default mode network (DMN). However, for older adults, post-effort increases in the RSFC of laHC–pHC were related to decreases in the RSFC of the laHC and right precentral gyrus. Thus, the correlation between intra-HC and inter-HC RSFC was altered with cognitive effort and aging. Importantly, older adults who had lower post-effort RSFC between the laHC and the pHC demonstrated a decline in episodic memory 2 years later. Hence, the change in intra-HC RSFC following cognitive effort was able to predict subsequent memory function with aging in our sample.

WAIS Information Subtest as an indicator of crystallized cognitive abilities and brain reserve among highly educated older adults: A three-year longitudinal study

The Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) Information Subtest (IS) is known as a neuropsychological "Hold" test that is relatively resistant to decline with aging. We administered neuropsychological tests among highly educated healthy older adults once a year for three subsequent years. Results showed highly stable performances on the IS across years (Mean Z score: T0 = 1.39, SD = 0.60; T1 = 1.37, SD = 0.77; T2 = 1.50, SD = 0.66; T3 = 1.48, SD = 0.66), that were significantly higher than zero (T0: t = 12.08; T1: t = 9.29; T2: t = 11.71; T3: t = 11.68; for all, p < 0.0001). In contrast, other neuropsychological tests showed differences in performance across time; some performances significantly declined (Rey Osterrieth Complex Figure test-copy, Rey-Auditory Verbal Learning Test, and Montreal Cognitive Assessment test [MoCA]), whereas others were improved, possibly due to practice effects (Rey Osterrieth Complex Figure test- delayed, Rey-Auditory Verbal Learning Test- delayed, and Trail Making Test- part A). Correlation with whole brain volumetric analysis revealed a positive correlation between gray matter volumes and IS scores (r = 0.46, p < 0.05) even when controlling for age and education (partial correlations: r = 0.43; r = 0.45, for both p < 0.05). No significant correlations were found between gray matter and other test scores. Therefore, the WAIS-III Information subtest appears to be an adequate neuropsychological measurement of crystallized ability in highly educated older adults and may be considered as a proxy measure of brain reserve.

How attention modulates encoding of dynamic stimuli in older adults

Aging is marked by memory decline that is exacerbated with attentional loading. Portraying older adults' neural functions when encoding information in conditions of high and low attentional load is a necessary step toward understanding this phenomenon. Furthermore, the information gained may be used to devise strategies aimed to prevent age-related decline in memory. To address this issue, a group of older adults underwent fMRI scanning while encoding short movies under two levels of attentional loading. High attentional load was associated with increased inter-subject correlation (inter-SC) in only a subset of prefrontal regions that were previously identified in younger adults. It was also associated with lower inter-SC in task-relevant visual regions, suggesting that as load increased, visual processing became less synchronized across participants. Critically, while we have shown that inter-SC in the dorsal posterior cingulate cortex (dPCC) was increased for younger adults at high load, older adults did not generally show this effect. However, those older adults who did display this pattern also displayed a 'younger-like' memory profile. These results point to a pivotal role of the dPCC in the interplay between attention and memory across the lifespan.

How Attention Modulates Encoding of Dynamic Stimuli

When encoding a real-life, continuous stimulus, the same neural circuits support processing and integration of prior as well as new incoming information. This ongoing interplay is modulated by attention, and is evident in regions such as the prefrontal cortex section of the task positive network (TPN), and in the posterior cingulate cortex (PCC), a hub of the default mode network (DMN). Yet the exact nature of such modulation is still unclear. To investigate this issue, we utilized an fMRI task that employed movies as the encoded stimuli and manipulated attentional load via an easy or hard secondary task that was performed simultaneously with encoding. Results showed increased intersubject correlation (inter-SC) levels when encoding movies in a condition of high, as compared to low attentional load. This was evident in bilateral ventrolateral and dorsomedial prefrontal cortices and the dorsal PCC (dPCC). These regions became more attuned to the combination of the movie and the secondary task as the attentional demand of the latter increased. Activation analyses revealed that at higher load the prefrontal TPN regions were more activated, whereas the dPCC was more deactivated. Attentional load also influenced connectivity within and between the networks. At high load the dPCC was anti-correlated to the prefrontal regions, which were more functionally coherent amongst themselves. Finally and critically, greater inter-SC in the dPCC at high load during encoding predicted lower memory strength when that information was retrieved. This association between inter-SC levels and memory strength suggest that as attentional demands increased, the dPCC was more attuned to the secondary task at the expense of the encoded stimulus, thus weakening memory for the encoded stimulus. Together, our findings show that attentional load modulated the function of core TPN and DMN regions. Furthermore, the observed relationship between memory strength and the modulation of the dPCC points to this region as a key area involved in the manipulation of attentional load on memory function.

Task-specific Aspects of Goal-directed Word Generation Identified via Simultaneous EEG–fMRI

Generating words according to a given rule relies on retrieval-related search and postretrieval control processes. Using fMRI, we recently characterized neural patterns of word generation in response to episodic, semantic, and phonemic cues by comparing free recall of wordlists, category fluency, and letter fluency [Shapira-Lichter, I., Oren, N., Jacob, Y., Gruberger, M., & Hendler, T. Portraying the unique contribution of the default mode network to internally driven mnemonic processes. Proceedings of the National Academy of Sciences, U.S.A., 110, 4950–4955, 2013]. Distinct selectivity for each condition was evident, representing discrete aspects of word generation-related memory retrieval. For example, the precuneus, implicated in processing spatiotemporal information, emerged as a key contributor to the episodic condition, which uniquely requires this information. Gamma band is known to play a central role in memory, and increased gamma power has been observed before word generation. Yet, gamma modulation in response to task demands has not been investigated. To capture the task-specific modulation of gamma power, we analyzed the EEG data recorded simultaneously with the aforementioned fMRI, focusing on the activity locked to and immediately preceding word articulation. Transient increases in gamma power were identified in a parietal electrode immediately before episodic and semantic word generation, however, within a different time frame relative to articulation. Gamma increases were followed by an alpha-theta decrease in the episodic condition, a gamma decrease in the semantic condition. This pattern indicates a task-specific modulation of the gamma signal corresponding to the specific demands of each word generation task. The gamma power and fMRI signal from the precuneus were correlated during the episodic condition, implying the existence of a common cognitive construct uniquely required for this task, possibly the reactivation or processing of spatiotemporal information.

The Montreal Cognitive Assessment in cognitively-intact elderly: a case for age-adjusted cutoffs

The Montreal Cognitive Assessment (MoCA) is a widely used screening test for evaluation of mild cognitive impairment (MCI), with a single cutoff for all ages. We examined whether it is associated with age in a sample of cognitively-intact elderly (CIE). The average MoCA score was negatively correlated with age and was significantly higher for younger than older CIE. Additionally, 42% of the older elderly fell below the proposed MCI cutoff score, although all subjects were CIE. Thus, cognitive abilities captured by the MoCA test decrease with age, even in CIE. Therefore, cutoff scores by age for the MoCA are needed.

Learning and memory-related brain activity dynamics are altered in systemic lupus erythematosus: a functional magnetic resonance imaging study

Background

Memory impairment is prevalent in systemic lupus erythematosus (SLE); however, the pathogenesis is unknown.

Methods

We studied 12 patients with SLE without clinically overt neuropsychiatric manifestations and 11 matched healthy controls, aiming to characterize neural correlates of memory impairment, using structural and functional magnetic resonance imaging (MRI). The paradigm consisted of three encoding and free-recall cycles, allowing characterization of dynamics along consecutive retrieval attempts.

Results

During learning, patients with SLE and healthy controls showed brain activity changes in two principal networks, the default mode network (DMN) and the task-positive network (TPN). Patients with SLE demonstrated significantly less deactivation in the DMN and greater activation in the TPN, reflecting greater recruitment of both networks. The anterior medial prefrontal cortex (amPFC) of the DMN emerged as the only region where brain activity dynamics were altered both over the learning process ( p < 0.006), and within free-recall period attempts ( p < 0.034). Patients showed significant positive correlations between learning efficiency and hippocampal activity, and greater hippocampal functional connectivity, with pronounced connectivity to DMN structures.

Conclusions

Increased brain activation in patients with SLE during learning may reflect compensatory mechanisms to overcome memory impairment. Our findings localize this impairment to the amPFC, consistent with the behavioral pattern seen in SLE. Altered networking of the hippocampal subsystem of the DMN is consistent with hippocampal neuronal damage seen in SLE, and may reflect compensatory cortical reorganization to cope with dysfunction in these regions pivotal to mnemonic functions.

Bcl-2 and p53 expression in insular and in well-differentiated thyroid carcinomas with an insular pattern

Expression of p53 and bcl-2 oncogenes was investigated in poorly differentiated, so-called insular carcinomas of the thyroid gland and also in the follicular and papillary carcinomas with an insular component. Hematoxylin-eosin sections of 217 thyroid carcinomas were reevaluated for insular carcinoma and also for thyroid carcinomas with an insular component. Immunohistochemical staining method was used for detecting p53 and bcl-2 expression on paraffin blocks of three pure insular, five follicular or papillary thyroid carcinomas with a major insular component (more than 50%) and six with a minor insular component (20-50%). Flow cytometry was also performed in these cases. None of the cases showed p53 immunoreactivity. Bcl-2 expression was observed in all cases and the most intense staining was seen in insular areas. All the cases were diploid. We suggest that bcl-2 plays a role in loss of differentiation of thyroid carcinomas.

Epithelial membrane antigen and S-100 protein expression in benign and malignant papillary thyroid neoplasms

Papillary carcinoma of the thyroid is mainly diagnosed with histopathologic features. Classical papillary architectures are important but nuclear change is the essential diagnostic element. Papillary architecture may be seen in benign lesions such as in hyperplastic areas of the follicular neoplasms, multinodular goiter and Grave's disease. Differential diagnosis of papillary carcinoma and papillary hyperplasia is very important for clinical management. Some authors have reported that Epithelial Membrane Antigen (EMA) and S-100 protein expression would be valuable and helpful in identifying papillary neoplasia and distinguishing it from papillary hyperplasia. In this study, EMA and S-100 protein expression of 14 papillary thyroid carcinomas and 13 papillary hyperplasias were studied by using immunohistochemical methods. In 14 papillary carcinomas, 9 showed diffuse and 3 revealed focal S-100 protein nuclear and cytoplasmic immunostaining. Two cases were not stained. All of the 13 papillary hyperplasias were negative for S-100 protein. EMA expression was observed in the apical cytoplasmic location of 11 papillary carcinomas except one case that showed diffuse cytoplasmic staining and one which was negative. In the papillary hyperplasias, 7 revealed both cytoplasmic and apical cytoplasmic staining. One case showed only cytoplasmic staining. Five cases were negative for EMA. The difference in the S-100 protein expression is significant, however immunostaining of EMA is similar in both lesions. We concluded that differential diagnosis of papillary structures in carcinomas and hyperplasias was mainly diagnosed on the histopathologic features but S-100 protein expression could be helpful in difficult cases.

Motor nerve terminal staining combined with catecholamine histofluorescence or immunocytochemistry

A number of excellent techniques are available to stain and characterize different types of neurons and nerve terminals. However, because these different techniques are frequently not compatible, their usefulness in determining the relationships between specific axons and neuromuscular junctions is often limited. The goal was to develop specific procedures for simultaneous visualization of different types of unmyelinated axons and motor nerve terminals in the same preparation. First we modified the formaldehyde/glutaraldehyde staining solutions of the aqueous aldehyde fluorescence technique (Faglu) to observe catecholamine containing axons in whole mount amphibian skeletal muscle. The compatibility of this modified staining solution with other histological procedures made it possible to stain both motor nerve terminals with tetrazolium salts and, in the same preparation, to observe unmyelinated axons with aldehyde-induced catecholamine histofluorescence. This same general formaldehyde/glutaraldehyde staining procedure was also used with immunocytochemical techniques to visualize fluorescent antibody stained nerves and motor nerve terminals in the same whole mount preparation.

Presence of alpha-melanocyte-stimulating hormone-like immunoreactivity in the innervation of amphibian skeletal muscle

Amphibian motor nerve terminals are sensitive to a wide variety of peptides, including alpha-melanocyte-stimulating hormone (alpha-MSH). We determined the presence and distribution of alpha-MSH-like immunoreactivity (alpha-MSHLI) in the innervation of the cutaneous pectoris muscle from bullfrog (Rana catesbeiana) tadpoles and postmetamorphic froglets, and adult frogs (R. catesbeiana and R. pipiens). alpha-MSHLI was found in unmyelinated, noncholinergic axons, in motor axons, and in motor nerve terminals. In motor axons, alpha-MSHLI was predominantly associated with neurofilaments. The distribution of this form of alpha-MSHLI changed during development and seasonally in adult frogs. The possible functional roles of this alpha-MSHLI are discussed.

Occurrence of cicatricial pemphigoid and leiomyosarcoma in a psoriatic patient

A psoriatic patient who developed cicatricial pemphigoid and leiomyosarcoma of the abdomen is presented. The sequence of events indicates a relationship between the cicatricial pemphigoid and the malignant disease.