Relationship between physical activity and specific working memory indicators of depressive symptoms in university students

BACKGROUND The detection rate of depression among university students has been increasing in recent years,becoming one of the main psychological diseases that endangers their physical and mental health.According to statistics,self-harm and suicide,for which there is no effective intervention,are the second leading causes of death.AIM To explore the relationship between different elements and levels of physical activity and college students’depression-symptom-specific working memory indicators.METHODS Of 143 college students were analyzed using the Beck Depression Self-Rating Scale,the Physical Activity Rating Scale,and the Working Memory Task.RESULTS There was a significant difference between college students with depressive symptoms and healthy college students in completing verbal and spatial working memory(SWM)tasks correctly(all P<0.01).Physical Activity Scale-3 scores were significantly and positively correlated with the correct rate of the verbal working memory task(r=0.166)and the correct rate of the SWM task(r=0.210)(all P<0.05).There were significant differences in the correct rates of verbal and SWM tasks according to different exercise intensities(all P<0.05)and different exercise durations(all P<0.05),and no significant differences in the correct rates of verbal and SWM tasks by exercise frequency(all P>0.05).CONCLUSION An increase in physical exercise among college students,particularly medium-and high-intensity exercise and exercise of 30 min or more,can improve the correct rate of completing working memory tasks.

Text Difficulty,Working Memory Capacity and Mind Wandering During Chinese EFL Learners’Reading

This experimental study investigated how text difficulty and different working memory capacity(WMC)affected Chinese EFL learners’reading comprehension and their tendency to engage in task-unrelated thoughts,that is,mind wandering(MW),in the course of reading.Sixty first-year university non-English majors participated in the study.A two-factor mixed experimental design of 2(text difficulty:difficult and simple)×2(WMC:high/large and low/small)was employed.Results revealed that 1)the main and interaction effects of WMC and text difficulty on voluntary MW were significant,whereas those on involuntary MW were not;2)while reading the easy texts,the involuntary MW of high-WMC individuals was less frequent than that of low-WMC ones,whereas while reading the difficult ones,the direct relationship between WMC and involuntary MW was not found;and that 3)high-WMC individuals had a lower overall rate of MW and better reading performance than low-WMC individuals did,but with increasing text difficulty,their rates of overall MW and voluntary MW were getting higher and higher,and the reading performance was getting lower and lower.These results lend support to WM theory and have pedagogical implications for the instruction of L2 reading.

Positive Effect of Transcranial Direct Current Stimulation on Visual Verbal Working Memory in Patients with Attention-Deficit/Hyperactivity Disorder

Background: Working memory is an executive function that plays an important role in many aspects of daily life, and its impairment in patients with attention-deficit/hyperactivity disorder (ADHD) affects quality of life. The dorsolateral prefrontal cortex (DLPFC) has been a good target site for transcranial direct current stimulation (tDCS) due to its intense involvement in working memory. In our 2018 study, tDCS improved visual-verbal working memory in healthy subjects. Objective: This study examines the effects of tDCS on ADHD patients, particularly on verbal working memory. Methods: We conducted an experiment involving verbal working memory of two modalities, visual and auditory, and a sustained attention task that could affect working memory in 9 ADHD patients. Active or sham tDCS was applied to the left DLPFC in a single-blind crossover design. Results: tDCS significantly improved the accuracy of visual-verbal working memory. In contrast, tDCS did not affect auditory-verbal working memory and sustained attention. Conclusion: tDCS to the left DLPFC improved visual-verbal working memory in ADHD patients, with important implications for potential ADHD treatments.

THE RELATION BETWEEN EVOLUTION OF SPATIAL WORKING MEMORY FUNCTION AND OF MORPHOLOGY OF THE DORSOLATERAL PREFRONTAL CORTEX AMONG THE RHESUS MONKEY, SLOW LORIS AND TREE SHREW

The relation between evolution of spatial working memory function and of morphology of the dorsolateral prefrontal cortex among the rhesus monkey (Macaca mulatta), the slow loris (Nycticebus coucang) and the tree shrew (Tupaia belangen chinensis) were reported in present paper. The results read as follows: In the DR performance with training, the rhesus monkeys and slow lorises could reach a criterion of 90% correct response at 1.1 ± 3.2 seconds, and 3.8±0.4 seconds delay interval, respectively, by 1000 training trails. The tree shrews failed to reach the criterion of 90% correct response even at 0 seconds delay interval by 1000 training trails. If a delay interval was tested in one session (30 trails) only, doing the DR performamce without training, the rhesus monkeys reached a correct of 80% or higher in each session at 0, 1, 2, 3, 4, and 5 seconds delay, respectively. The percent correct in each session of the slow lorises showed no differences from the rhesus monkeys at 0, 1, 2, 3, and 4 seconds delay. However, when the delay interval was increased to 5 seconds, the percent correct of the DR performance declined to 70% or lower in the slow lorises. In the tree shrews the percent correct in each session reached to 70% or lower at 0, 1, 2, 3, 4, and 5 seconds delay interval, respectively. The morphological studies revealed that the size of the prefrontal cortex increased, and the structure got complex in the course of the evolution in primates. It is suggested that the relation of evolution between the spatial working memory function and anatomy in the prefrontal cortex might be significant among the three species, both the development of morphology and that of the spatial working memory function in the dorsolateral prefrontal cortex are later than other regions of cerebral cortex in phylogenetic evolution course.

Working Memory in Language Use

This paper investigates the working memory in two aspects of language use, vocabulary acquisition and language comprehension. It is involved both in language acquisition and second language learning.

Working-memory training improves developmental dyslexia in Chinese children

Although plasticity in the neural system underlies working memory, and working memory can be improved by training, there is thus far no evidence that children with developmental dyslexia can benefit from working-memory training. In the present study, thirty dyslexic children aged 8-11 years were recruited from an elementary school in Wuhan, China. They received working-memory training including training in visuospatial memory, verbal memory, and central executive tasks. The difficulty of the tasks was adjusted based on the performance of each subject, and the training sessions lasted 40 minutes per day, for 5 weeks. The results showed that working-memory training significantly enhanced performance on the nontrained working memory tasks such as the visuospatial, the verbal domains, and central executive tasks in children with developmental dyslexia. More importantly, the visual rhyming task and reading fluency task were also significantly improved by training. Progress on working memory measures was related to changes in reading skills. These experimental findings indicate that working memory is a pivotal factor in reading development among children with developmental dyslexia, and interventions to improve working memory may help dyslexic children to become more proficient in reading.

Inter- and intra-hemispheric EEG coherence in patients with mild cognitive impairment at rest and during working memory task

Objective： To assess functional relationship by calculating inter- and intra-hemispheric electroencephalography （EEG） coherence at rest and during a working memory task of patients with mild cognitive impairment （MCI）. Methods： The sample consisted of 69 subjects： 35 patients （n = 17 males, n = 18 females; 52-71 years old） and 34 normal controls （n = 17 males, n = 17 females; 51 -63 years old）. Mini-mental state examination （MMSE） of two groups revealed that the scores of MCI patients did not differ significantly from those of normal controls （P〉0.05）. In EEG recording, subjects were performed at rest and during working memory task. EEG signals from F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 electrode pairs are resulted from the inter-hemispheric action, and EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs are resulted from the intra-hemispheric action for delta （1.0-3.5 Hz）, theta （4.0-7.5 Hz）, alpha-1 （8.0-10.0 Hz）, alpha-2 （10.5-13.0 Hz）, beta-1 （13.5-18.0 Hz） and beta-2 （18.5-30.0 Hz） frequency bands. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined using fast Fourier transformation from the 16 sampled channels. Results： During working memory tasks, the inter- and intra-hemispheric EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group （P〈0.05）. However, there was no significant difference in inter- and intra-hemispheric EEG coherences between two groups at rest. Conclusion： Experimental results comprise evidence that MCI patients have higher degree of functional connectivity between hemispheres and in hemispheres during working condition, It suggests that MCI may be associated with compensatory processes during working memory tasks between hemispheres and in hemispheres. Moreover, failure of normal cortical connections may exist in MCI patients.

Working Memory Function in Chinese Dyslexic Children:A Near-Infrared Spectroscopy Study

The deficiency theories of dyslexia are quite contradictory and the cross-cultural studies in recent years mainly focused on whether the dyslexics among cultures shared the same cognitive profile or just based on the language.This study used Near-Infrared Spectroscopy (NIRS) imaging to measure the regional cerebral blood volume (BV) and the changes of cerebral activation in the left prefrontal cortex of 12 Chinese dyslexic children and their 12 age-matched normal controls during the Paced Vis-ual Serial Addition Test (PVSAT).Results showed that the scores of PVSAT of dyslexic children were significantly lower than those of the normal children (t=3.33,P<0.01).The activations of the left pre-frontal cortex in the normal group were significantly greater than those of dyslexic children (all P<0.01).Our results indicated that Chinese dyslexia had a general deficiency in working memory and this may be caused by the abnormal metabolic activity of brain blood volume in the left prefrontal cortex and the deficits in brain function might be the basis of neuropathology of Chinese dyslexia.Present study sup-ports the difference on brain activation of dyslexics from different languages may be caused by the same cognitive system related to reading.

Low-level lead exposure effects on spatial reference memory and working memory in rats

BACKGROUND： Studies have demonstrated that lead exposure can result in cognitive dysfunction and behavior disorders. However, lead exposure impairments vary under different experimental conditions. OBJECTIVE： To detect changes in spatial learning and memory following low-level lead exposure in rats, in Morris water maze test under the same experimental condition used to analyze lead exposure effects on various memory types and learning processes. DESIGN AND SETTING： The experiment was conducted at the Animal Laboratory, Institute of Psychology, Chinese Academy of Science between February 2005 and March 2006. One-way analysis of variance （ANOVA） and behavioral observations were performed. MATERIALS： Sixteen male, healthy, adult, Sprague Dawley rats were randomized into normal con-trol and lead exposure groups （n = 8）. METHODS： Rats in the normal control group were fed distilled water, and those in the lead exposure group were fed 250 mL of 0.05% lead acetate once per day. At day 28, all rats performed the Morris water maze test, consisting of four phases： space navigation, probe test, working memory test, and visual cue test. MAIN OUTCOME MEASURES： Place navigation in the Morris water maze was used to evaluate spatial learning and memory, probe trials for spatial reference memory, working memory test for spatial working memory, and visual cue test for non-spatial cognitive function. Perkin-Elmer Model 300 Atomic Absorption Spectrometer was utilized to determine blood lead levels in rats. RESULTS： （1） In the working memory test, the time to reach the platform remained unchanged between the control and lead exposure groups （F（1,1） = 0.007, P = 0.935）. A visible decrease in escape latencies was observed in each group （P = 0.028）. However, there was no significant difference between the two groups （F（1,1） = 1.869, P = 0.193）. The working memory probe test demonstrated no change between the two groups in the time spent in the target quadrant during the working memory probe test （F（1,1） = 1.869, P = 0.193）. However, by day 4, differences were observed in the working memory test （P 〈 0.01）. （2） Multivariate repetitive measure and ANOVA in place navigation presented no significant difference between the two groups （F（1,1） = 0.579, P = 0.459）. （3） Spatial probe test demonstrated that the time to reach the platform was significantly different between the two groups （F（1,1） = 4.587, P = 0.048）, and one-way ANOVA showed no significant difference in swimming speed between the two groups （F（1,1） = 1.528, P = 0.237）. （4） In the visual cue test, all rats reached the platform within 15 seconds, with no significant difference （F（1,1） = 0.579, P = 0.459）. （5） During experimentation, all rats increased in body mass, but there was no difference between the two groups （F（1,1） = 0.05, P = 0.943）. At day 28 of 0.05% lead exposure, the blood lead level was 29.72 μg/L in the lead exposure group and 5.86 μg/L in the control group （P 〈 0.01）. CONCLUSION： The present results revealed low-level lead exposure significantly impaired spatial reference memory and spatial working memory, but had no effect on spatial learning.

Study on EEG power and coherence in patients with mild cognitive impairment during working memory task

To investigate the features of electroencephalography （EEG） power and coherence at rest and during a working memory task of patients with mild cognitive impairment （MCI）. Thirty-five patients （17 males, 18 females; 52-71 years old） and 34 sex- and age-matched controls （17 males, 17 females; 51-63 years old） were recruited in the present study. Mini-Mental State Examination （MMSE） of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls （P〉0.05）. Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels： fight and left frontal （F3, F4）, central （C3, C4）, parietal （P3, P4）, temporal （T5, T6） and occipital （O1, O2）; inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta （1.0-3.5 Hz）, theta （4.0-7.5 Hz）, alpha-1 （8.0-10.0 Hz）, alpha-2 （10.5-13.0 Hz）, beta-1 （13.5-18.0 Hz） and beta-2 （18.5-30.0 Hz） frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high （P〈0.05） in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group （P〈0.05）. However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working memory tasks. Moreover, failure of normal cortical connections may be exist in MCI patients.

Analysis of influencing factors of visual working memory in young adult patients with schizophrenia

Background Patients with schizophrenia have general cognitive impairments, and the impairment of working memory is considered to be the basis of cognitive impairments. The research on visual working memory, one of the subcomponents, is getting more and more attention.However, the influencing factors which cause the deficits of visual working memory in patients with schizophrenia have not been clearly explained. To provide evidence for cognitive impairment interventions, the present study explored the factors influencing the deficits of patients' visual working memory.Aim The present study discussed the relevant factors influencing the visual working memory of patients with schizophrenia by measuring the accuracy of the visual working memory of patients with schizophrenia and healthy controls.Methods Colour-recall paradigm was employed to measure the accuracy of the visual working memory of 61 healthy controls and 61 patients who met the International Classification of Diseases, Tenth Revision diagnostic criteria for schizophrenia. The age range of subjects was18-50. Scale for the Assessment of Positive Symptoms(SAPS) and Scale for the Assessment of Negative Symptoms(SANS) were used to evaluate the patients' clinical symptoms.Results Compared with the healthy control group, the accuracy of visual working memory of patients with schizophrenia was significantly impaired(t=3.062,p=0.003). The accuracy of visual working memory of patients with schizophrenia was not related to age(r=0.023,p=0.860),the age of onset(r=-0.003,p=0.979),the duration of illness(r=-0.038, p=0.769),education level(r=-0.181, p=0.162),continuous working time before illness(r =-0.107, p=0.413) or the daily dose of antipsychotic drugs(r =0.062, p=0.635); however, it was positively related to the number of hospitalisations(r =0.471,p<0.001). The total score of Scale for the Assessment of Positive Symptoms(SAPS) was negatively related to the accuracy of visual working memory(r=-0.388, p=0.005), while the total score of Scale for the Assessment of Negative Symptoms(SANS)(r=0.416,p=0.001), the total score of diminished emotional expressiveness(r =0.352, p=0.005) and the total score of attention disorder(r =0.310, p=0.015) were positively related to the accuracy of visual working memory. Patients using a single drug and those using multiple drugs were compared with each other. They were not significantly different in age(t=0.010, p=0.992), the number of hospitalisations(t=0.656, p=0.514), the duration of illness(t=0.701, p=0.486), the total score of SANS(t=0.078,p=0.938), the total score of SAPS(t=1.815, p=0.079) and the daily dose of antipsychotic drugs(t=1.794, p=0.078).However, in order to explore whether single or combined drug use would affect the accuracy of visual working memory of patients with schizophrenia, the present study also compared these two groups' different SO values of the accuracy of visual working memory. The results showed that the accuracy of visual working memory of patients with schizophrenia with combined drug use was significantly better than that of patients with single drug use(t=2.515, p=0.015, independent sample t-test).Conclusion The present study indicates that the visual working memory of young adult patients with schizophrenia is impaired compared with the healthy people within the same age range. The impairment is more obvious in patients who have multiple hospitalisations and suffer from severe negative symptoms. The impairment in patients with more severe positive symptoms is not very obvious. Combined drug use is likely to alleviate the impairment.

Alpha spectral power and coherence in the patients with mild cognitive impairment during a three-level working memory task

Objective： The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment （MCI） was investigated. Methods：Subjects included 35 MCI patients according to the DSM-Ⅳ criteria （mean age： 62.3, SD： 6.5） and 34 healthy controls （mean age：57.4, SD： 4.0） were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph （EEG） signal was recorded. The spectral EEG power was computed over alphal （8.0～10.0 Hz） and alpha2 （10.5～13.0 Hz） frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal （F3-F4）, central （C3-C4）, parietal （P3-P4）, temporal （T5-T6） as well as occipital （O1-O2） was compared between MCI patients and normal controls. The EEG signals from F3-C3,F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alphal and alpha2 frequency bands. Result： There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks （P〈0.001）. The inter- and intra-hemispheric coherence during working memory tasks showed a ＂drop to rise＂ tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls.When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion： The results of the present study indicate that the alpha frequency band may be the characteristic band in distinguishing MCI patients from normal controls during working memory tasks. MCI patients exhibit greater inter-hemispheric connectivity than intra-hemispheric connectivity when memory demands increase. MCI patients mobilize a compensatory mechanism to maintain the processing effectiveness while the processing efficiency is reduced.

What emotion dimensions can affect working memory performance in healthy adults?A review

Due to the critical roles of emotion and working memory in our daily activities,a great deal of attention has been given to how emotion influences working memory performance.Although the association between emotion and working memory is relatively well established,whether mood enhances or impairs working memory performance remains controversial.The present review provides a relatively representative overview of the research on the effect of different dimensions of emotion on working memory among healthy adults spanning a 30-year period.The findings show that the valence,arousal and motivational dimensions of emotion could all exert an impact on working memory performance.The impact of emotion on working memory might be modulated by task relevance,emotion type,working memory paradigms and individual differences.The vast majority of the studies regarding the effect of emotion on working memory performance focused on the impact of negatively valenced affect and yielded highly contradictory findings.The impacts of arousal and motivation on working memory have been less explored,and inconsistent findings have also been reported.Possible explanations are discussed.Considerable research on the effect of certain dimensions of emotion on working memory has suffered from a lack of control of other emotional dimensions,and different aspects of working memory have been investigated by various paradigms.Directions for further studies should include the exploration of specific dimensions of emotion on different aspects of working memory,with the other dimensions being well controlled.

Effect of propofol on local field potential in rat prefrontal cortex during working memory task

Propofol may produce memory impairment during anesthesia procedure. Local field potentials (LFPs) are used with increasing frequency in recent years to link neural activity to perception and cognition. In this study, effect of propofol on LFPs in rat’s prefrontal cortex during working memory task was evaluated. Young (approximately 3 month) male Sprague-Dawley rats were divided into two group: propofol rats and control rats. Propofol rats received propofol at 0.9 mg/Kg·min intravenously for 2 h. After 12 h, LFPs of all rats were measured simultaneously from multiple electrodes placed in prefrontal cortex while rats were performing a working memory task in Y-maze. LFPs instantaneous phase were obtained by applying Hilbert transform, and cross-correlation coherence of LFPs was calculated. The results indicate that propofol decreased the correct rate and crosscorrelation coherence of LFPs on the first two days (p 0.05). Our results suggest that propofol can impair cross-correlation coherence of LFPs in the first two days, but not long time.

On the Role of Working Memory in the Comprehension of Conversational Implicatures

According to theory,working memory capacity should be related to comprehension ability,in this thesis,it tries to jus tify the relationship between working memory capacity and comprehension of conversational implicatures.Through theoretical hypothesizing and empirical demonstration,the relationship between working memory and the comprehension of conversational implicatures,especially role that the phonological loop plays in the comprehension of conversational implicatures caused by literal violation to the maxim of manner,is justified in the thesis.

Role of hippocampal dentate gyrus neurons in the protective effects of heat shock factor 1 on working memory

Increasing evidence suggests that heat shock factor 1 exerts endogenous protective effects on working memory under conditions of chronic psychological stress. However, the precise underlying mechanisms remain poorly understood. This study examined the protective factors affecting working memory in heat shock transcription factor 1 gene knockout mice. The results indicated that the number of correct T maze alternations decreased following mild chronic psychological stress in knockout mice. This change was accompanied by a decrease in neurogenesis and an increase in neuronal apoptosis in the hippocampal dentate gyrus. The number of correct T maze alternations was positively correlated with neurogenesis in hippocampal dentate gyrus, and negatively correlated with neuronal apoptosis. In wild type mice, no significant difference was detected in the number of correct T maze alternations or neuronal apoptosis in hippocampal dentate gyrus. These results indicate that the heat shock factor 1 gene has an endogenous protective role in working memory during mild chronic psychological stress associated with dentate gyrus neuronal apoptosis Moreover, dentate gyrus neurogenesis appears to participate in the protective mechanism.

Investigating Efficacy of “Working Memory Training Software” on Students Working Memory

The aim of the present study is developing “Working Memory Training Software”, and investigating its content validity and the efficacy of this computerized cognitive training on students working memory. This study is in R & D research category, and it is performed in a semi-experimental design. Its data were collected from students of the third grade (30), fourth grade (30), and fifth grade (12) of primary school. After specifying the software content validity by asking expertise opinions, and investigating these opinions through Spearman Test (rs = 1), these children attended in intervention program for 10 sessions. The subtests of working memory in “Tehran-Stanford-Binet Intelligence Scale” and “Wechsler intelligence scale for children” were conducted in all three groups on the pre-test and post-test. After elimination of the pre-test effect, Paired-Samples T-Test on total scores of subtests of working memory in “Tehran-Stanford Binet Intelligence Scale” (t = 10.869, df = 71, r = 0.967 & P < 0.05) and in “Wechsler intelligence scale for children” (t = 16.809, df = 71, r = 0.983 & P < 0.05) reveals a significant difference in post-test scores. Based on this study the Working Memory Training Software has proper psychometric properties and causes significant improvement in students working memory performance.

Long-Term Electrophysiological and Behavioral Analysis on the Improvement of Visual Working Memory Load, Training Gains, and Transfer Benefits

Recent evidence demonstrates that with training, one can enhance visual working memory (VWM) capacity and attention over time in the near transfer tasks. Not only do these studies reveal the characteristics of VWM load and the influences of training, they may also provide insights into developing effective rehabilitation for patients with VWM deficiencies. However, few studies have investigated VWM over extended periods of time and evaluated transfer benefits on non-trained tasks. Here, we combined behavioral and electroencephalographical approaches to investigate VWM load, training gains, and transfer benefits. Our results reveal that VWM capacity is directly correlated to the difference of event-related potential waveforms. In particular, the “magic number 4” can be observed through the contralateral delay amplitude and the average capacity is 3.25-item over 15 participants. Furthermore, our findings indicate that VWM capacity can be improved through training;and after training exercises, participants from the training group are able to dramatically improve their performance. Likewise, the training effects on non-trained tasks can also be observed at the 12th week after training. Therefore, we conclude that participants can benefit from training gains, and augmented VWM capacity sustained over long periods of time on specific variety of tasks.

Differential Effect of Acute Stress on Visuospatial Working Memory and Sexual Motivation in Male Rats

Working memory is an executive function that is highly dependent on the functioning of the prefrontal cortex. Several studies using food or drink as rewards have demonstrated that rats are capable of performing tasks that involve working memory. Sexual behavior is another highly-rewarding, motivated behavior that has proven to be an efficient incentive in classical operant tasks. Considering that both sexual behavior and working memory are sensitive to the effects of stress, the aim of this study was to determine the effect of acute stress on visuospatial working memory during a sexually-motivated task (a nonmatching-to-sample task in a T-maze) in male rats. Thirty-two male Wistar rats were trained in the T-maze using sexual interaction (intromission and ejaculation) as a reinforcer during a 4-day training period (training sessions held every 4th day). On the basis of their performance, the rats were classified as good-learners (n = 12) and bad-learners (n = 20), and on the fifth day, 6 good-learners and 10 bad-learners were subjected to stress using the cold water immersion model (CWI, 15&deg;C) for 15 minutes before they were evaluated in the T-maze. The remaining rats made up the control group (i.e., they performed the task without previous stress). Results showed that acute stress by CWI improved working memory in the bad-learners but did not affect the performance of the good-learners, although in both groups (good- and bad-learners) stress decreased the sexual motivation to perform the task. It is probable that the increased levels of corticosterone in the stress situation could activate glutamatergic transmission in the prefrontal cortex, thus facilitating working memory and, simultaneously, decreasing testosterone levels, which exerts a negative effect on sexual motivation in these male rats.