Sternberg Memory Task Research Articles

PEARL-Neuro Database: EEG, fMRI, health and lifestyle data of middle-aged people at risk of dementia

Interdisciplinary approaches are needed to understand the relationship between genetic factors and brain structure and function. Here we describe a database that includes genetic data on apolipoprotein E (APOE) and phosphatidylinositol binding clathrin assembly protein (PICALM) genes, both of which are known to increase the risk of late-onset Alzheimer's disease, paired with psychometric (memory, intelligence, mood, personality, stress coping strategies), basic demographic and health data on a cohort of 192 healthy middle-aged (50–63) individuals. Part of the database (~79 participants) also includes blood tests (blood counts, lipid profile, HSV virus) and functional neuroimaging data (EEG/fMRI) recorded with a resting-state protocol (eyes open and eyes closed) and two cognitive tasks (multi-source interference task, MSIT; and Sternberg's memory task). The data were validated and showed overall good quality. This open-science dataset is well suited not only for research relating to susceptibility to Alzheimer's disease but also for more general questions on brain aging or can be used as part of meta-analytical multi-disciplinary projects.

The Effects of Acute Exercise and Virtual Reality Tasks on Children’s Memory Function and Exercise Preference

Background: It is well established that regular participation in exercise and virtual reality (VR) environments are important tools for improving or maintaining human health and cognitive function. Objectives: This study examined the effects of acute exercise and VR environments on children’s memory function and exercise preference (i.e. cycling with or without the use of VR technology). Methods: Α 2×3 factorial design was adopted with two measures (pre, post) and three study groups. Forty-five healthy children aged 9 to 13 years (Mage = 10.91±1.24 years) voluntarily participated in the study. Participants were randomly assigned into three groups receiving different treatment: (1) an exercise+VR group that cycled for 15 min in a VR environment (forest path) combined with basic mathematical problem-solving tasks, (2) an exercise group that cycled for 15 min, and (3) a no-exercise group that sat in a specific place in a lab for 15 min (the control group). Before and after the acute exercise, all the groups completed the Sternberg Memory Task. Upon completion of the intervention, the two exercise groups completed measures of enjoyment, intention and attitudes towards cycling. The exercise+VR group also completed a scale capturing the VR’s usability. Results: The results show that the exercise group scored higher on Sternberg’s Memory Task (p .05) after the acute exercise treatment (post) than before it (pre). Similarly, the exercise+VR participants scored higher on the post-intervention memory task than did the exercise and control groups (p .05). Moreover, the exercise+VR group reported higher scores on enjoyment, intention and attitude towards cycling than the exercise group, but this difference was not statistically significant (p .05). Finally, the exercise+VR participants recorded high scores on the usability of the VR system during the acute exercise programme. Conclusions: These findings are in line with those of previous studies, underlining the important roles of exercise and VR environments on youths’ cognitive function.

Working Memory Load Influence on Control of Attention among Malaysian Undergraduates

The study investigates how working memory affects students' control of attention. A quasi-experimental research is conducted individually on 52 undergraduates of a public university in Malaysia, enrolled in various full-time undergraduate programmes, using Sternberg memory task and Task-switching tests. The reaction time is taken in milliseconds (ms) to differentiate the results for both tasks. The analysis revealed that when memory load was increased, reaction time also escalated. In the task-switching test, when one task was given at any one time, the reaction time was swift; however, when two or more tasks were integrated into one task, the reaction time would subsequently decelerated. Although the study also revealed that there is no significant difference between genders in terms of handling memory load and task-switching. However, a significant relationship was observed in performances between memory load and task-switching. It is also evidenced in the study that when memory load increases, it compounds the reaction time for task-switching. Results from the study inform course instructors to be aware of cognitive load when chunking information and assigning tasks to students, as their decisions on content quantity bore an effect on what would be remembered when students learn.

Auditory cortex supports verbal working memory capacity.

Working memory (WM) is a fundamental construct of human cognition. The neural basis of auditory WM is thought to reflect a distributed brain network consisting of canonical memory and central executive brain regions including frontal lobe and hippocampus. Yet, the role of auditory (sensory) cortex in supporting active memory representations remains controversial. Here, we recorded neuroelectric activity via electroencephalogram as listeners actively performed an auditory version of the Sternberg memory task. Memory load was taxed by parametrically manipulating the number of auditory tokens (letter sounds) held in memory. Source analysis of scalp potentials showed that sustained neural activity maintained in auditory cortex (AC) prior to memory retrieval closely scaled with behavioral performance. Brain-behavior correlations revealed that lateralized modulations in left (but not right) AC were predictive of individual differences in auditory WM capacity. Our findings confirm a prominent role of AC, traditionally viewed as a sensory-perceptual processor, in actively maintaining memory traces and dictating individual differences in behavioral WM limits.

Effect of Unilateral Left Nostril Breathing (Chandra Anga Pranayama) on Cognitive Function in Healthy Yoga-Naïve Individuals: A Randomized, Controlled, Pilot Study

Introduction: Breathing modulates cortical neuronal activity. Various breathing exercises are purported to have specific effects on emotional and cognitive functions. Objective: To determine the effect of unilateral left nostril breathing (ULNB) on nonlateralized, overall cognitive functions using computerized psychometric tests. Methods: A randomized, controlled, pilot study was conducted among 20 healthy yoga-naïve medical students. ULNB was performed for 15 min by the test group (n = 10) and breath awareness by the control group (n = 10). Attention and processing speed, memory, and executive function were assessed using the Letter-Digit Substitution Test, Sternberg Memory Task, and Victoria Stroop Test, respectively. Baseline, pre- and postintervention scores were recorded. Results: There was no significant difference between the groups in baseline scores. In the Sternberg Memory Task, a statistically significant decrease in response time was seen in the test (t(9) = 3.855, p = 0.004) as well as the control group (t(9) = 3.120, p = 0.012); there was no significant difference between the groups. No significant effect of UNLB was seen in the Letter-Digit Substitution Test and Stroop Test. Conclusions: Our study showed no difference in the effects of 15-min practice of ULNB and breath awareness on cognitive functions; both improved memory but not attention or executive function.

PO063 Value of Chronotropic Index In Chagas Disease Without Proven Pathology

We presented cognitively healthy older adults and patients with mild cognitive impairment (MCI) three versions of a modified Sternberg memory task designed to range in difficulty from low to high. Among cognitively healthy older adults, blood pressure responses assessed during the work periods rose with difficulty. By contrast, among MCI patients, blood pressure responses assessed during the work periods were low irrespective of difficulty. Findings are discussed primarily in relation to a conceptual analysis concerned with ability determinants of effort (task engagement) and associated cardiovascular responses. They also are discussed in the context of other recent cardiovascular studies involving older adults and with regard to the potential for exaggerated cardiovascular responses to accelerate cognitive decline in advanced age.

Auditory Discrimination and Short Term Memory are Preserved during Simulated Altitude and Moderate Intensity Exercise.

PURPOSE: This study was conducted to examine the cognitive and neurophysiological effects of acute exposure to simulated moderate and high altitudes at rest and during exercise to examine whether short term memory or auditory oddball task performance were affected beyond a certain threshold of simulated altitude and whether exercise improves or worsens cognitive function during these conditions. METHODS: Fourteen recreationally active college students (M=9, F=5) aged 18-35 participated in this study, which consisted of six experimental days, with three simulated altitude conditions: sea level (SL), simulated moderate altitude (MA; 15.4% FIO2, ~2400 m) or simulated high altitude (HA; 12.8% FIO2, ~3900 m); and two exercise conditions: rest or moderate intensity cycling exercise at 60% altitude-specific peak power output, in a randomized-order, crossover design. Accuracy and reaction time on an auditory oddball task and a Sternberg memory task were assessed, alongside the amplitudes and latencies of their associated event-related potentials. RESULTS: Exercise improved auditory reaction time, regardless of altitude (p<0.01), though task accuracy was not affected under any condition. In addition, simulated altitude induced lower P300 amplitudes and slower latencies during the auditory oddball task (p<0.01), while exercise improved latencies at HA and SL, but not at MA (p=0.03). Sternberg memory task behavioral performance was not affected by either simulated altitude or exercise. However, P200 latency was slowed during exercise trials (p=0.02) as well as during MA trials (p<0.01). CONCLUSIONS: Acute exposure to simulated moderate and high altitudes may not significantly impact short term memory and auditory discrimination. On the other hand, an acute bout of moderate intensity cycling exercise may improve reaction time on oddball tasks, even though it does not seem to benefit short term memory. It is possible that these cognitive modalities were negatively affected by simulated altitude, as evidenced by some altered event-related potentials, but that these effects were either too small to translate into performance deficits or that there are as yet unknown compensatory mechanisms at work that preserve performance as one ascends to altitude, at least until 3900 m.

Regional brain activity that determines successful and unsuccessful working memory formation.

Using EEG source reconstruction with Multiple Sparse Priors (MSP), we investigated the regional brain activity that determines successful memory encoding in two participant groups of high and low accuracy rates. Eighteen healthy young adults performed a sequential fashion of visual Sternberg memory task. The 32-channel EEG was continuously measured during participants performed two 70 trials of memory task. The regional brain activity corresponding to the oscillatory EEG activity in the alpha band (8-13 Hz) during encoding period was analyzed by MSP implemented in SPM8. We divided the data of all participants into 2 groups (low- and highperformance group) and analyzed differences in regional brain activity between trials in which participants answered correctly and incorrectly within each of the group. Participants in low-performance group showed significant activity increase in the visual cortices in their successful trials compared to unsuccessful ones. On the other hand, those in high-performance group showed a significant activity increase in widely distributed cortical regions in the frontal, temporal, and parietal areas including those suggested as Baddeley's working memory model. Further comparison of activated cortical volumes and mean current source intensities within the cortical regions of Baddeley's model during memory encoding demonstrated that participants in high-performance group showed enhanced activity in the right premotor cortex, which plays an important role in maintaining visuospatial attention, compared to those in low performance group. Our results suggest that better ability in memory encoding is associated with distributed and stronger regional brain activities including the premotor cortex, possibly indicating efficient allocation of cognitive load and maintenance of attention.

Optical measures of changes in cerebral vascular tone during voluntary breath holding and a Sternberg memory task

The human cerebral vasculature responds to changes in blood pressure and demands for oxygenation via cerebral autoregulation. Changes in cerebrovascular tone (vasoconstriction and vasodilation) also mediate the changes in blood flow measured by the BOLD fMRI signal. This cerebrovascular reactivity is known to vary with age. In two experiments, we demonstrate that cerebral pulse parameters measured using optical imaging can quantify changes in cerebral vascular tone, both globally and locally. In experiment 1, 51 older adults (age range=55–87) performed a voluntary breath-holding task while cerebral pulse amplitude measures were taken. We found significant pulse amplitude variations across breath-holding periods, indicating vasodilation during, and vasoconstriction after breath holding. The breath-holding index (BHI), a measure of cerebrovascular reactivity (CVR) was derived and found to correlate with age. BHI was also correlated with performance in the Modified Mini-Mental Status Examination, even after controlling for age and education. In experiment 2, the same participants performed a Sternberg task, and changes in regional pulse amplitude between high (set-size 6) and low (set-size 2) task loads were compared. Only task-related areas in the fronto-parietal network (FPN) showed significant reduction in pulse amplitude, indicating vasodilation. Non-task-related areas such as the somatosensory and auditory cortices did not show such reductions. Taken together, these experiments suggest that optical pulse parameters can index changes in brain vascular tone both globally and locally, using both physiological and cognitive load manipulations.

Difficulty, effort and cardiovascular response to a working memory challenge: Older adults with and without mild cognitive impairment

We presented cognitively healthy older adults and patients with mild cognitive impairment (MCI) three versions of a modified Sternberg memory task designed to range in difficulty from low to high. Among cognitively healthy older adults, blood pressure responses assessed during the work periods rose with difficulty. By contrast, among MCI patients, blood pressure responses assessed during the work periods were low irrespective of difficulty. Findings are discussed primarily in relation to a conceptual analysis concerned with ability determinants of effort (task engagement) and associated cardiovascular responses. They also are discussed in the context of other recent cardiovascular studies involving older adults and with regard to the potential for exaggerated cardiovascular responses to accelerate cognitive decline in advanced age.

Effects of light wavelength on MEG ERD/ERS during a working memory task

We investigated the effects of light wavelengths on cortical oscillatory activity associated with working memory processes. Cortical activity responses were measured using magnetoencephalography (MEG) while participants performed an auditory Sternberg memory task during exposure to light of different wavelength. Each trial of the memory task consisted of four words presented as a memory set and one word presented as a probe. All words were presented audibly. Participants were instructed to indicate whether the probe word was or was not presented within the memory set. A total of 90 trials were conducted under the light exposure. Event-related synchronization (ERS) and event-related desynchronization responses in the alpha frequency range during the task were analyzed. Results showed that, during memory encoding, ERS responses were significantly greater in the short-wavelength (blue) light condition than in the middle-wavelength (green) light condition, approximately 20–30min after the onset of light exposure. Behavioral performance was very high throughout the experiment and there was no difference between the light conditions. Although the light effects were not observed in behavior, the result of ERS suggests that 20–30min of exposure to blue light enhances cortical activity related to active memory maintenance and/or attention to auditory stimuli.

Efficient mental workload estimation using task-independent EEG features

Objective. Mental workload is frequently estimated by EEG-based mental state monitoring systems. Usually, these systems use spectral markers and event-related potentials (ERPs). To our knowledge, no study has directly compared their performance for mental workload assessment, nor evaluated the stability in time of these markers and of the performance of the associated mental workload estimators. This study proposes a comparison of two processing chains, one based on the power in five frequency bands, and one based on ERPs, both including a spatial filtering step (respectively CSP and CCA), an FLDA classification and a 10-fold cross-validation. Approach. To get closer to a real life implementation, spectral markers were extracted from a short window (i.e. towards reactive systems) that did not include any motor activity and the analyzed ERPs were elicited by a task-independent probe that required a reflex-like answer (i.e. close to the ones required by dead man’s vigilance devices). The data were acquired from 20 participants who performed a Sternberg memory task for 90 min (i.e. 2/6 digits to memorize) inside which a simple detection task was inserted. The results were compared both when the testing was performed at the beginning and end of the session. Main results. Both chains performed significantly better than random; however the one based on the spectral markers had a low performance (60%) and was not stable in time. Conversely, the ERP-based chain gave very high results (91%) and was stable in time. Significance. This study demonstrates that an efficient and stable in time workload estimation can be achieved using task-independent spatially filtered ERPs elicited in a minimally intrusive manner.

Coherence and phase lag index analyses — A preliminary MEG/EEG sensor-level study on functional connectivities during the Sternberg memory task

Coherence and phase lag index analyses — A preliminary MEG/EEG sensor-level study on functional connectivities during the Sternberg memory task

Effects of baroreceptor stimulation on performance of the Sternberg short-term memory task: A cardiac cycle time study

Activation of arterial baroreceptors can affect cortical activity. Cardiac cycle time studies have established that natural variations in baroreceptor activation are associated with changes in basic sensorimotor function whereas few have investigated more complex cognitive function. Aiming to improve our understanding of this phenomenon, this study examined performance on the Sternberg memory task as a function of the phase of the cardiac cycle. In each trial, participants were shown either two or six digits followed by a probe digit that either had or had not been presented previously and were required to press one of two response buttons to indicate a match and mismatch, respectively. Response latency per additional digit was greater for stimuli presented late compared to early in the cardiac cycle whereas the zero intercept was greatest at the start of the cardiac cycle and reduced as the cycle progressed. These findings provide evidence that natural baroreceptor stimulation can affect complex cognitive processes, such as serial-comparison in short-term memory, as well as basic sensorimotor processes.

Memory and mood during MDMA intoxication, with and without memantine pretreatment

Previous studies have shown that single doses of MDMA can affect mood and impair memory in humans. The neuropharmacological mechanisms involved in MDMA-induced memory impairment are not clear. Memantine, an NMDA and alpha 7 nicotinic acetylcholine (ACh) receptor antagonist, was able to reverse MDMA-induced memory impairment in rats. This study investigated whether treatment with memantine can prevent MDMA-induced memory impairment in humans.15 subjects participated in a double-blind, placebo controlled, within-subject design. Subjects received both pre-treatment (placebo/memantine 20 mg) (T1) and treatment (placebo/MDMA 75 mg) (T2) on separate test days. T1 preceded T2 by 120 min. Memory function was assessed 90 min after T2 by means of a Visual Verbal Learning Task, a Prospective Memory Task, the Sternberg Memory Task and the Abstract Visual Pattern Learning Task. Profile of Mood State and psychomotor performance were also assessed to control whether MDMA and memantine interactions would selectively pertain to memory or transfer to other domains as well.MDMA significantly impaired performance in the visual verbal learning task and abstract visual pattern learning task. Pre-treatment with memantine did not prevent MDMA-induced memory impairment in these two tasks. Both positive (vigour, arousal, elation) and negative mood effects (anxiety) were increased by MDMA. The responses were not altered by pretreatment with memantine which had no effect on memory or mood when given alone.These preliminary results suggest that memantine does not reverse MDMA-induced memory impairment and mood in humans.This article is part of the Special Issue entitled ‘CNS Stimulants’.

Wearing Ergonomically Designed Core Stability Shorts Improves Cognitive Control and Affect Following Acute Aerobic Exercise

This study examined whether wearing a pair of core-supporting gym shorts influenced cognitive control and mood state follows aerobic exercise in young adults. Cognitive performance and the event related P3 potential were measured. Twenty-four adults were assigned to either the core-supporting shorts group or the normal shorts group. Participants completed 30 minutes of an acute treadmill exercise involving walking and/or running at an intensity of 70% HRmax. They next performed a modified Sternberg memory task, in which participants encoded a letter array and determine if a probe letter had been presented in the preceding set of memory items. Results indicated that the core-supporting shorts group exhibited greater response accuracy and larger P3 amplitudes as compared to the normal shorts group. In addition, the core-supporting shorts group reported more pleasantness and relaxation than the normal shorts group. These results suggest that wearing the core-supporting shorts improves the cognitive control associated with working memory and induces a positive effect as well.

Posttraumatic stress disorder is associated with limited executive resources in a working memory task

Patients with posttraumatic stress disorder (PTSD) can show declines in working memory. A dual-task design was used to determine whether these impairments are linked to executive control limitations. Participants performed a Sternberg memory task with either one or four letters. In the dual-task condition, the maintenance period was filled with an arrow flanker task. PTSD patients were less accurate on the working memory task than were controls, especially in the dual-task condition. In the single-task condition, both groups showed similar patterns of brain potentials from 300 to 500ms when discriminating old and new probes. However, when taxed with an additional task, the event-related potentials (ERPs) of the PTSD group no longer differentiated old and new probes. In contrast, interference resolution processes in both the single- and dual-task conditions of the flanker task were intact. The lack of differentiation in the ERPs reflects impaired working memory performance under more difficult, dual-task conditions. Exacerbated difficulty in performing a working memory task with concurrent task demands suggests a specific limitation in executive control resources in PTSD.

P9.4 Cognitive event-related potentials: method for testing features of working memory using the Sternberg memory task

P9.4 Cognitive event-related potentials: method for testing features of working memory using the Sternberg memory task

Real-Time Brain Oscillation Detection and Phase-Locked Stimulation Using Autoregressive Spectral Estimation and Time-Series Forward Prediction

Neural oscillations are important features in a working central nervous system, facilitating efficient communication across large networks of neurons. They are implicated in a diverse range of processes such as synchronization and synaptic plasticity, and can be seen in a variety of cognitive processes. For example, hippocampal theta oscillations are thought to be a crucial component of memory encoding and retrieval. To better study the role of these oscillations in various cognitive processes, and to be able to build clinical applications around them, accurate and precise estimations of the instantaneous frequency and phase are required. Here, we present methodology based on autoregressive modeling to accomplish this in real time. This allows the targeting of stimulation to a specific phase of a detected oscillation. We first assess performance of the algorithm on two signals where the exact phase and frequency are known. Then, using intracranial EEG recorded from two patients performing a Sternberg memory task, we characterize our algorithm's phase-locking performance on physiologic theta oscillations: optimizing algorithm parameters on the first patient using a genetic algorithm, we carried out cross-validation procedures on subsequent trials and electrodes within the same patient, as well as on data recorded from the second patient.

Effects of working memory load on visual selective attention: behavioral and electrophysiological evidence.

Working memory and attention interact in a way that enables us to focus on relevant items and maintain current goals. The influence of working memory on attention has been noted in several studies using dual task designs. Multitasking increases the demands on working memory and reduces the amount of resources available for cognitive control functions such as resolving stimulus conflict. However, few studies have investigated the temporal activation of the cortex while multitasking. The present study addresses the extent to which working memory load influences early (P1) and late (P300) attention-sensitive event-related potential components using a dual task paradigm. Participants performed an arrow flanker task alone (single task condition) or concurrently with a Sternberg memory task (dual task condition). In the flanker task, participants responded to the direction of a central arrow surrounded by congruent or incongruent arrows. In the dual task condition, participants were presented with a Sternberg task that consisted of either four or seven consonants to remember prior to a short block of flanker trials. Participants were slower and less accurate on incongruent versus congruent trials. Furthermore, accuracy on incongruent trials was reduced in both dual task conditions. Likewise, P300 amplitude to incongruent flanker stimuli decreased when working memory load increased. These findings suggest that interference from incongruent flankers was more difficult to suppress when working memory was taxed. In addition, P1 amplitude was diminished on all flanker trials in the dual task condition. This result indicates that top-down attentional control over early visual processing is diminished by increasing demands on working memory. Both the behavioral and electrophysiological results suggest that working memory is critical in maintaining attentional focus and resolving conflict.