Excitotoxic median raphe lesions aggravate working memory storage performance deficits caused by scopolamine infusion into the dentate gyrus of the hippocampus in the inhibitory avoidance task in rats

The interactions between the median raphe nucleus (MRN) serotonergic system and the septohippocampal muscarinic cholinergic system in the modulation of immediate working memory storage performance were investigated. Rats with sham or ibotenic acid lesions of the MRN were bilaterally implanted with cannulae in the dentate gyrus of the hippocampus and tested in a light/dark step-through inhibitory avoidance task in which response latency to enter the dark compartment immediately after the shock served as a measure of immediate working memory storage. MRN lesion per se did not alter response latency. Post-training intrahippocampal scopolamine infusion (2 and 4 µg/side) produced a more marked reduction in response latencies in the lesioned animals compared to the sham-lesioned rats. Results suggest that the immediate working memory storage performance is modulated by synergistic interactions between serotonergic projections of the MRN and the muscarinic cholinergic system of the hippocampus.

Cognitive performance of young and elderly subjects on the free word recall memory test: effect of presentation order on recall order

The influence of aging on memory has been extensively studied, but the importance of short-term memory and recall sequence has not. The objective of the current study was to examine the recall order of words presented on lists and to determine if age affects recall sequence. Physically and psychologically healthy male subjects were divided into two groups according to age, i.e., 23 young subjects (20 to 30 years) and 50 elderly subjects (60 to 70 years) submitted to the Wechsler Adult Intelligence Scale-Revised and the free word recall test. The order of word presentation significantly affected the 3rd and 4th words recalled (P < 0.01; F = 14.6). In addition, there was interaction between the presentation order and the type of list presented (P < 0.05; F = 9.7). Also, both groups recalled the last words presented from each list (words 13-15) significantly more times 3rd and 4th than words presented in all remaining positions (P < 0.01). The order of word presentation also significantly affected the 5th and 6th words recalled (P = 0.05; F = 7.5) and there was a significant interaction between the order of presentation and the type of list presented (P < 0.01; F = 20.8). The more developed the cognitive functions, resulting mainly from formal education, the greater the cognitive reserve, helping to minimize the effects of aging on the long-term memory (episodic declarative).

Predicting performance on fluid intelligence from speed of processing, working memory, and controlled attention

Fluid inteliigence has been defined as an innate ability to reason which is measured commonly by the Raven's Progressive Matrices (RPM). Individual differences in fluid intelligence are currently explained by the Cascade model (Fry & Hale, 1996) and the Controlled Attention hypothesis (Engle, Kane, & Tuholski, 1999; Kane & Engle, 2002). The first theory is based on a complex relation among age, speed, and working memory which is described as a Cascade. The alternative to this theory, the Controlled Attention hypothesis, is based on the proposition that it is the executive attention component of working memory that explains performance on fluid intelligence tests. The first goal of this study was to examine whether the Cascade model is consistent within the visuo-spatial and verbal-numerical modalities. The second goal was to examine whether the executive attention component ofworking memory accounts for the relation between working memory and fluid intelligence. Two hundred and six undergraduate students between the ages of 18 and 28 completed a battery of cognitive tests selected to measure processing speed, working memory, and controlled attention which were selected from two cognitive modalities, verbalnumerical and visuo-spatial. These were used to predict performance on two standard measures of fluid intelligence: the Raven's Progressive Matrices (RPM) and the Shipley Institute of Living Scales (SILS) subtests. Multiple regression and Structural Equation Modeling (SEM) were used to test the Cascade model and to determine the independent and joint effects of controlled attention and working memory on general fluid intelligence. Among the processing speed measures only spatial scan was related to the RPM. No other significant relations were observed between processing speed and fluid intelligence. As 1 a construct, working memory was related to the fluid intelligence tests. Consistent with the predictions for the RPM there was support for the Cascade model within the visuo-spatial modality but not within the verbal-numerical modality. There was no support for the Cascade model with respect to the SILS tests. SEM revealed that there was a direct path between controlled attention and RPM and between working memory and RPM. However, a significant path between set switching and RPM explained the relation between controlled attention and RPM. The prediction that controlled attention mediated the relation between working memory and RPM was therefore not supported. The findings support the view that the Cascade model may not adequately explain individual differences in fluid intelligence and this may be due to the differential relations observed between working memory and fluid intelligence across different modalities. The findings also show that working memory is not a domain-general construct and as a result its relation with fluid intelligence may be dependent on the nature of the working memory modality.

Autonomic and electrocortical indices of performance monitoring and source memory discrimination in older and younger adults

Reduced capacity for executive cognitive function and for the autonomic control of cardiac responsivity are both concomitants of the aging process. These may be linked through their mutual dependence on medial prefrontal function, but the specifics ofthat linkage have not been well explored. Executive functions associated with medial prefrontal cortex involve various aspects ofperformance monitoring, whereas centrally mediated autonomic functions can be observed as heart rate variability (HRV), i.e., variability in the length of intervals between heart beats. The focus for this thesis was to examine the degree to which the capacity for phasic autonomic adjustments to heart rate relates to performance monitoring in younger and older adults, using measures of electrocortical and autonomic activity. Behavioural performance and attention allocation during two age-sensitive tasks could be predicted by various aspects of autonomic control. For young adults, greater influence of the parasympathetic system on HRV was beneficial for learning unfamiliar maze paths; for older adults, greater sympathetic influence was detrimental to these functions. Further, these relationships were primarily evoked when the task required the construction and use of internalized representations of mazes rather than passive responses to feedback. When memory for source was required, older adults made three times as many source errors as young adults. However, greater parasympathetic influence on HRV in the older group was conducive to avoiding source errors and to reduced electrocortical responses to irrelevant information. Higher sympathetic predominance, in contrast, was associated with higher rates of source error and greater electrocortical responses tq non-target information in both groups. These relations were not seen for 11 errors associated with a speeded perceptual task, irrespective of its difficulty level. Overall, autonomic modulation of cardiac activity was associated with higher levels of performance monitoring, but differentially across tasks and age groups. With respect to age, those older adults who had maintained higher levels of autonomic cardiac regulation appeared to have also maintained higher levels of executive control over task performance.

The effect of motor-encoding activities on memory and performance in a grade one reading program

This study examined the effectiveness of motor-encoding activities on memory and performance of students in a Grade One reading program. There were two experiments in the study. Experiment 1 replicated a study by Eli Saltz and David Dixon (1982). The effect of motoric enactment (Le., pretend play) of sentences on memory for the sentences was investigated. Forty Grade One students performed a "memory-for-sentences" technique, devised by Saltz and Dixon. Only the experimental group used motoric enactment of the sentences. Although quantitative findings revealed no significant difference between the mean scores of the experimental group versus the control group, aspects of the experimental design could have affected the results. It was suggested that Saltz and Dixon's study could be replicated again, with more attention given to variables such as population size, nature of the test sentences, subjects' previous educational experience and conditions related to the testing environment. The second experiment was an application of Saltz and Dixon's theory that motoric imagery should facilitate memory for sentences. The intent was to apply this theory to Grade One students' ability to remember words from their reading program. An experimental gym program was developed using kinesthetic activities to reinforce the skills of the classroom reading program. The same subject group was used in Experiment 2. It was hypothesized that the subjects who experienced the experimental gym program would show greater signs of progress in reading ability, as evidenced by their scores on Form G of the Woodcock Reading Mastery Test--Revised. The data from the WRM--R were analyzed with a 3-way split-plot analysis of variance in which group (experimental vs. control) and sex were the between subjects variables and test-time (pre-test vs. post-test) was the within-subjects variable. Findings revealed the following: (a) both groups made substantial gains over time on the visual-auditory learning sub-test and the triple action of group x sex x time also was significant; (b) children in the experimental and control groups performed similarly on both the pre- and post-test of the letter identification test; (c) time was the only significant effect on subjects' performance on the word identification task; (d) work attack scores showed marked improvement in performance over time for both the experimenta+ and control groups; (e) passage comprehension scores indicated an improvement in performance for both groups over time. Similar to Experiment 1, it is suggested that several modifications in the experimental design could produce significant results. These factors are addressed with suggestions for further research in the area of active learning; more specifically, the effect of motor-encoding activities on memory and academic performance of children.

Memory for articulated sequences and lipreading performance of deaf observers

This paper is a review of a study to determine the relation between lipreading performance and memory for sequences of spoken syllables.

The influence of affective statements on performance on implicit and explicit memory tasks

Consumers are often exposed to brand names presented concurrently with information such as brand claims and warnings, prior to making product choices. As implicit memory has been implicated in the consumer choice process, two experiments were conducted to assess the influence of additional information, namely simple positive and negative statements, on implicit and explicit memory tasks. In Experiment 1, the mere presence of additional statements at study significantly reduced performance on a two-alternatives forced recognition task. However, the same manipulation had no effect on implicit preference judgement task performance. The valence of the accompanying information had no effect on either task. In Experiment 2, using modified implicit and explicit choice tasks, performance on the former was unaffected by statement valence, whereas the latter task was. Hence, positive priming was obtained for brand names previously shown with negative information. The results of the experiments are discussed in relation to both implicit memory and consumer choice.

Food for thought: the role of dietary flavonoids in enhancing human memory, learning and neuro-cognitive performance

Emerging evidence suggests that dietary-derived flavonoids have the potential to improve human memory and neuro-cognitive performance via their ability to protect vulnerable neurons, enhance existing neuronal function and stimulate neuronal regeneration. Long-term potentiation (LTP) is widely considered to be one of the major mechanisms underlying memory acquisition, consolidation and storage in the brain and is known to be controlled at the molecular level by the activation of a number of neuronal signalling pathways. These pathways include the phosphatidylinositol-3 kinase/protein kinase B/Akt (Akt), protein kinase C, protein kinase A, Ca-calmodulin kinase and mitogen-activated protein kinase pathways. Growing evidence suggests that flavonoids exert effects on LTP, and consequently memory and cognitive performance, through their interactions with these signalling pathways. Of particular interest is the ability of flavonoids to activate the extracellular signal-regulated kinase and the Akt signalling pathways leading to the activation of the cAMP-response element-binding protein, a transcription factor responsible for increasing the expression of a number of neurotrophins important in LTP and long-term memory. One such neurotrophin is brain-derived neurotrophic factor, which is known to be crucial in controlling synapse growth, in promoting an increase in dendritic spine density and in enhancing synaptic receptor density. The present review explores the potential of flavonoids and their metabolite forms to promote memory and learning through their interactions with neuronal signalling pathways pivotal in controlling LTP and memory in human subjects.

Providing extrinsic reward for test performance undermines long-term memory acquisition

Based on numerous studies showing that testing studied material can improve long-term retention more than restudying the same material, it is often suggested that the number of tests in education should be increased to enhance knowledge acquisition. However, testing in real-life educational settings often entails a high degree of extrinsic motivation of learners due to the common practice of placing important consequences on the outcome of a test. Such an effect on the motivation of learners may undermine the beneficial effects of testing on long-term memory because it has been shown that extrinsic motivation can reduce the quality of learning. To examine this issue, participants learned foreign language vocabulary words, followed by an immediate test in which one-third of the words were tested and one-third restudied. To manipulate extrinsic motivation during immediate testing, participants received either monetary reward contingent on test performance or no reward. After 1 week, memory for all words was tested. In the immediate test, reward reduced correct recall and increased commission errors, indicating that reward reduced the number of items that can benefit from successful retrieval. The results in the delayed test revealed that reward additionally reduced the gain received from successful retrieval because memory for initially successfully retrieved words was lower in the reward condition. However, testing was still more effective than restudying under reward conditions because reward undermined long-term memory for concurrently restudied material as well. These findings indicate that providing performance–contingent reward in a test can undermine long-term knowledge acquisition.

Energy-performance tradeoffs in software transactional memory

Transactional memory (TM) is a new synchronization mechanism devised to simplify parallel programming, thereby helping programmers to unleash the power of current multicore processors. Although software implementations of TM (STM) have been extensively analyzed in terms of runtime performance, little attention has been paid to an equally important constraint faced by nearly all computer systems: energy consumption. In this work we conduct a comprehensive study of energy and runtime tradeoff sin software transactional memory systems. We characterize the behavior of three state-of-the-art lock-based STM algorithms, along with three different conflict resolution schemes. As a result of this characterization, we propose a DVFS-based technique that can be integrated into the resolution policies so as to improve the energy-delay product (EDP). Experimental results show that our DVFS-enhanced policies are indeed beneficial for applications with high contention levels. Improvements of up to 59% in EDP can be observed in this scenario, with an average EDP reduction of 16% across the STAMP workloads. © 2012 IEEE.

Analysis of slow- and fast-alpha band asymmetry during performance of a saccadic eye movement task: Dissociation between memory- and attention-driven systems

This study aimed at analyzing the relationship between slow- and fast-alpha asymmetry within frontal cortex and the planning, execution and voluntary control of saccadic eye movements (SEM), and quantitative electroencephalography (qEEG) was recorded using a 20-channel EEG system in 12 healthy participants performing a fixed (i.e., memory-driven) and a random SEM (i.e., stimulus-driven) condition. We find main effects for SEM condition in slow- and fast-alpha asymmetry at electrodes F3-F4, which are located over premotor cortex, specifically a negative asymmetry between conditions. When analyzing electrodes F7-F8, which are located over prefrontal cortex, we found a main effect for condition in slow-alpha asymmetry, particularly a positive asymmetry between conditions. In conclusion, the present approach supports the association of slow- and fast-alpha bands with the planning and preparation of SEM, and the specific role of these sub-bands for both, the attention network and the coordination and integration of sensory information with a (oculo)-motor response. (C) 2011 Elsevier B.V. All rights reserved.

Age, sex, and performance influence the visuospatial working memory network in childhood

This study describes the influence of age, sex, and working memory (WM) performance on the visuospatial WM network. Thirty-nine healthy children (7-12 years) completed a dot location functional magnetic resonance imaging (fMRI) task. Percent signal change measured the intensity and laterality indices measured the asymmetry of activation in frontal and parietal brain regions. Old children showed greater intensity of activation in parietal regions than young children but no differences in lateralization were observed. Intensity of activation was similar across sex and WM performance groups. Girls and high WM performers showed more right-sided lateralization of parietal regions than boys and low WM performers.