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Memory Performance (memory + performance)
Selected AbstractsFunctional MRI Predicts Memory Performance after Right Mesiotemporal Epilepsy SurgeryEPILEPSIA, Issue 2 2005Jozsef Janszky Summary:,Purpose: Anterior temporal lobe resection (ATR) is a treatment option in drug-resistant epilepsy. An important risk of ATR is loss of memory because mesiotemporal structures contribute substantially to memory function. We investigated whether memory-activated functional MRI (fMRI) can predict postoperative memory loss after anterior temporal lobectomy in right-sided medial temporal lobe epilepsy (MTLE). Methods: We included 16 patients (10 women) aged 16,54 years. The mean age at epilepsy onset was 12.5 years (range, 1,26 years). The patients' mean Wechsler IQ score was 95.2 (range, 62,125). The activation condition of fMRI consisted of retrieval from long-term memory induced by self-paced performance of an imaginative walk. All but one patient had left-sided speech dominance according to speech-activated fMRI. Outside the scanner, we evaluated the pre- and postoperative visual memory retention by using Rey Visual Design Learning Test. Results: We found a correlation between the preoperative asymmetry index of memory- fMRI and the change between pre- and postsurgical measures of memory retention. Reduced activation of the mesiotemporal region ipsilateral to the epileptogenic region correlated with a favorable memory outcome after right-sided ATR. Conclusions: In light of the postoperative results, the theoretical implication of our study is that fMRI based on a simple introspective retrieval task measures memory functions. The main clinical implication of our study is that memory- fMRI might replace the invasive Wada test in MTLE by using a simple fMRI paradigm. Predictive power, however, will be studied in larger patient samples. Other studies are required for left-sided MTLE and neocortical epilepsies to assess the clinical usefulness of memory- fMRI. [source] Wada Memory Performance Predicts Seizure Outcome after Epilepsy Surgery in ChildrenEPILEPSIA, Issue 7 2003Gregory P. Lee Summary: Purpose: Wada memory asymmetries were examined in children from four comprehensive epilepsy surgery centers who subsequently underwent epilepsy surgery to determine whether Wada memory performance could predict degree of seizure relief in children. Methods: One hundred fifty-six children (between ages 5 and 16 years) with intractable epilepsy underwent Wada testing before resective epilepsy surgery (93 within the left hemisphere, and 63 within the right hemisphere). Memory stimuli were presented soon after intracarotid amobarbital injection, and recognition memory for the items was assessed after return to neurologic baseline. Eighty-eight children underwent unilateral temporal lobe resection, and 68 had extratemporal lobe resections. One hundred four (67%) children were seizure free (Engel class I), and 52 (33%) were not seizure free (Engel classes II,IV) at follow-up (mean follow-up interval, 2.3 years). Results: Seizure-free children recalled 19.3% more Wada memory items after ipsilateral injection than did non,seizure-free children (p = 0.008). If analysis was restricted to youngsters with temporal lobectomies (TLs), seizure-free children recalled 27.7% more items after ipsilateral injection than did non,seizure-free TL children (p = 0.004). With regard to individual patient prediction, 75% of children who had memory score asymmetries consistent with the seizure focus were seizure free. In contrast, only 56% of children whose memory score asymmetries were inconsistent with the seizure focus were seizure free (p = 0.01). Conclusions: Results suggest that Wada memory performance asymmetries are related to the degree of seizure relief after epilepsy surgery in children and adolescents. [source] Preparation and Memory Performance of a Nanoaggregated Dispersed Red 1-Functionalized Poly (N -vinylcarbazole) Film via Solution-Phase Self-AssemblyADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Xiao-Dong Zhuang Abstract A nanoaggregated dispersed red 1-grafted poly(N -vinylcarbazole) (abbreviated PVDR) is self-assembled via ,,, stacking interactions of the carbazole groups in the polymer system after adding a solution of PVDR in N,N -dimethylformamide to dichloromethane. Upon self-assembly, the nanoaggregated PVDR film displays helical columnar stacks with large grain sizes, whereas a non-aggregated PVDR film exhibits an amorphous morphology with smaller grain size. A write-once read-many-times (WORM) memory device is shown whereby a pre-assembled solution of PVDR is spin-coated as the active layer and is sandwiched between an aluminum electrode and an indium-tin-oxide (ITO) electrode. This device shows very good memory performance, with an ON/OFF current ratio of more than 105 and a low misreading rate through the precise control of the ON and OFF states. The stability of the nanoaggregated PVDR device is much higher than that of the non-nanoaggregated PVDR device. This difference in device stability under constant voltage stress can be mainly attributed to the difference in the film crystallinity and surface morphology. No degradation in current density was observed for the ON- and OFF-states after more than one hundred million (108) continuous read cycles indicating that both states were insensitive to the read cycles. These results render the nanoaggregated PVDR polymer as promising components for high-performance polymer memory devices. [source] Comparison of single vs. multiple administrations of the AMPA receptors modulator S 18986 in the object recognition task in ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2007V. Bertaina-Anglade Abstract The present study aimed at defining the best scheme of administration of the , -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-positive modulator (S)-2,3-dihydro-[3,4]-cyclopentano-1,2,4-benzothiadiazine-1,1-dioxide (S 18986) [once daily (o.d.) administration of 1 mg/kg for 3 days vs. three times daily (t.i.d.) administration of 0.3 mg/kg for 3 days] to get an optimal procognitive activity in the object recognition task in rats. Memory performance [Recognition Index (RI)] of rats was significantly improved 1 h (RI = 41%, P < 0.01) and 3 h (RI = 46%, P < 0.001) following oral administration of S 18986 (1 mg/kg, o.d.) when compared with animals receiving the vehicle (RI = 6%). When the interval between administration and testing was increased to 6 h and 9 h, no statistically significant improvement in memory performance was observed (RI = 42% for 6 h and RI = 18% for 9 h vs. 20% for the vehicle group). When S 18986 was administered at 0.3 mg/kg t.i.d., no statistically significant improvement in memory performance was observed (RI = 36%). These findings show a long-lasting efficacy of the AMPA receptor allosteric modulator in the object recognition task despite a short half-life in plasma and in brain (approximately 1 h). Accordingly, multiple administrations of S 18986 are not required to obtain a maximal efficacy in this paradigm, because a o.d. schedule of administration leads to a powerful procognitive activity. [source] No persisting effect of partial sleep curtailment on cognitive performance and declarative memory recall in adolescentsJOURNAL OF SLEEP RESEARCH, Issue 1-Part-I 2010MARTA KOPASZ Summary Growing evidence indicates that sleep facilitates learning and memory processing. Sleep curtailment is increasingly common in adolescents. The aim of this study was to examine the effects of short-term sleep curtailment on declarative memory consolidation in adolescents. A randomized, cross-over study design was chosen. Twenty-two healthy subjects, aged 14,16 years, spent three consecutive nights in the sleep laboratory with a bedtime of 9 h during the first night (adaptation), 4 h during the second (partial sleep curtailment) and 9 h during the third night (recovery). The control condition consisted of three consecutive nights with bedtimes of 9 h. Both experimental conditions were separated by at least 3 weeks. The acquisition phase for the declarative tests was between 16:00 and 18:00 hours before the second night. Memory performance was examined in the morning after the recovery night. Executive function, attention and concentration were also assessed to control for any possible effects of tiredness. During the 4-h night, we observed a curtailment of 50% of non-rapid eye movement (non-REM), 5% of slow wave sleep (SWS) and 70% of REM sleep compared with the control night. Partial sleep curtailment of one night did not influence declarative memory retrieval significantly. Recall in the paired-associate word list task was correlated positively with percentage of non-REM sleep in the recovery night. Declarative memory consolidation does not appear to be influenced by short-term sleep curtailment in adolescents. This may be explained by the high ability of adolescents to compensate for acute sleep loss. The correlation between non-REM sleep and declarative memory performance supports earlier findings. [source] APEX-Map: a parameterized scalable memory access probe for high-performance computing systems,CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 17 2007Erich Strohmaier Abstract The memory wall between the peak performance of microprocessors and their memory performance has become the prominent performance bottleneck for many scientific application codes. New benchmarks measuring data access speeds locally and globally in a variety of different ways are needed to explore the ever increasing diversity of architectures for high-performance computing. In this paper, we introduce a novel benchmark, APEX-Map, which focuses on global data movement and measures how fast global data can be fed into computational units. APEX-Map is a parameterized, synthetic performance probe and integrates concepts for temporal and spatial locality into its design. Our first parallel implementation in MPI and various results obtained with it are discussed in detail. By measuring the APEX-Map performance with parameter sweeps for a whole range of temporal and spatial localities performance surfaces can be generated. These surfaces are ideally suited to study the characteristics of the computational platforms and are useful for performance comparison. Results on a global-memory vector platform and distributed-memory superscalar platforms clearly reflect the design differences between these different architectures. Published in 2007 by John Wiley & Sons, Ltd. [source] Do memory complaints represent impaired memory performance in patients with major depressive disorder?DEPRESSION AND ANXIETY, Issue 10 2008Arash Mowla M.D. Abstract Memory complaints are found to be associated with depression. However, the question is, "How much these subjective complaints indicate objective memory impairments?" The aim of this study is to determine whether subjective memory complaints represent objective memory impairments and to establish the demographic and clinical characteristics of patients with major depressive disorder (MDD) and subjective memory complaints. Sixty-four patients with MDD were assessed for objective memory performance through subtests of the Wechsler Memory Scale-III. Memory complaints also were assessed in these patients with a structured interview. Thirty healthy controls were also included in the study to compare memory performance among groups. The Hamilton Rating Scale for Depression was used to measure the severity and characteristics of depression. Patients with MDD who had longer duration and earlier onset of depression reported more memory complaints. MDD patients with memory complaints had more hypochondriac concerns but not more depression severity compared with those without memory complaints. There was no relationship between subjective memory complaints and objective memory performance in MDD patients. Patients with MDD with and without memory complaints had lower scores on the Wechsler Memory Scale-III than the control group. Subjective memory complaints are not a valid indictor of objective memory impairments, and the diagnostic value of self-reported memory is being questioned in patients with MDD. The cognitive status of MDD patients should be assessed routinely, regardless of the patient awareness of his or her cognitive deficits. Depression and Anxiety, 2008. © 2007 Wiley-Liss, Inc. [source] Memory deficits in children with and at risk for anxiety disordersDEPRESSION AND ANXIETY, Issue 2 2007Roma A. Vasa M.D. Abstract There are limited data on the neurocognitive correlates of childhood anxiety disorders. The objective of this study was to examine whether visual and verbal memory deficits of nonemotional stimuli are (1) a shared feature of three common childhood anxiety disorders (social phobia, separation anxiety disorder, and generalized anxiety disorder) or whether these deficits are restricted to specific anxiety disorders, and (2) present in offspring who possess at least one of the following established risk factors for anxiety disorders, parental history of panic disorder (PD), or major depressive disorder (MDD). One hundred and sixty offspring, ages 9,20 years, were recruited from parents with lifetime diagnoses of PD, MDD, PD plus MDD, or neither illness. Different clinicians blindly administered semistructured diagnostic interviews to offspring and parents. Verbal and visual memory subtests of the Wide Range Assessment of Memory and Learning were administered to offspring. The results showed that offspring with ongoing social phobia demonstrated reduced visual but not verbal memory scores compared to those without social phobia when controlling for offspring IQ, separation anxiety disorder, and generalized anxiety disorder. No other offspring anxiety disorder predicted memory performance. Neither parental PD nor parental MDD was associated with offspring memory performance. These findings are relevant to understanding the phenomenology of childhood anxiety disorders and may provide insights into the neural circuits underlying these disorders. Depression and Anxiety 24:85,94, 2007. Published 2006 Wiley-Liss, Inc. [source] Selective memory and memory deficits in depressed inpatientsDEPRESSION AND ANXIETY, Issue 4 2003Thomas Ellwart Dipl. Abstract We investigated memory impairment and mood-congruent memory bias in depression, using an explicit memory test and an implicit one. Thirty-six severely depressed inpatients that fulfilled DSM-IV criteria for major depressive disorder and 36 healthy controls matched for sex, age, and educational level participated in the study. Explicit memory was assessed with a free recall task and implicit memory with an anagram solution task. Results showed that depressed and controls differed in explicit memory performance, depending on the amount of cognitive distraction between incidental learning and testing. Implicit memory was not affected. In addition, severely depressed patients showed a mood-congruent memory bias in implicit memory but not in explicit memory. The complex pattern of results is discussed with regard to relevant theories of depression. Depression and Anxiety 17:197,206, 2003. © 2003 Wiley-Liss, Inc. [source] Hippocampal lesions impair spatial memory performance, but not song,A developmental study of independent memory systems in the zebra finchDEVELOPMENTAL NEUROBIOLOGY, Issue 8 2009David J. Bailey Abstract Songbirds demonstrate song- and spatial-learning, forms of memory that appear distinct in formal characteristics and fitting the descriptions and criteria of procedural and episodic-like memory function, respectively. As in other vertebrates, the neural pathways underlying these forms of memory may also be dissociable, and include the corresponding song circuit and hippocampus (HP). Whether (or not) these two memory systems interact is unknown. Interestingly, the HP distinguishes itself as a site of immediate early gene expression in response to song and as a site of estrogen synthesis, a steroid involved in song learning. Thus, an interaction between these memory systems and their anatomical substrates appears reasonable to hypothesize, particularly during development. To test this idea, juvenile male or female zebra finches received chemical lesions of the HP at various points during song learning, as did adults. Song structure, singing behavior, song preference, and spatial memory were tested in adulthood. Although lesions of the HP severely compromised HP-dependent spatial memory function across all ages and in both sexes, we were unable to detect any effects of HP lesions on song learning, singing, or song structure in males. Interestingly, females lesioned as adults, but not as juveniles, did lose the characteristic preference for their father's song. Since compromise of the neural circuits that subserve episodic-like memory does very little (if anything) to affect procedural-like (song learning) memory, we conclude that these memory systems and their anatomical substrates are well dissociated in the developing male zebra finch. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 [source] Recollective experience in alcohol dependence: a laboratory studyADDICTION, Issue 12 2008Patrizia Thoma ABSTRACT Aims Alcohol dependence has been linked to dysfunction of fronto-temporo-striatal circuits which mediate memory and executive function. The present study aimed to explore the specificity of recognition memory changes in alcohol dependence. Design, setting and participants Twenty hospitalized alcohol-dependent detoxified patients and 20 healthy control subjects completed a verbal list discrimination task. Measurements Hits and false alarm rates were analysed. Additionally, both the dual process signal detection model (DPSD) and the process dissociation procedure (PDP) were used to derive estimates of the contribution of recollection and familiarity processes to the recognition memory performance in patients and controls. Findings Alcohol-dependent patients showed intact hit rates, but increased false alarm rates and an impaired ability to remember the learning context. Both the DPSD model and PDP estimates yielded significantly reduced recollection estimates in the alcohol-dependent compared to control subjects. Whether or not familiarity was impaired, depended upon the sensitivity of the estimation procedure. Conclusion Taken together, the result pattern suggests a significant impairment in recollection and mild familiarity changes in recently detoxified, predominantly male, alcohol-dependent subjects. [source] Electrical Stimulation of the Hippocampal Epileptic Foci for Seizure Control: A Double-Blind, Long-Term Follow-Up StudyEPILEPSIA, Issue 10 2007Ana Luisa Velasco Summary:,Purpose: Our aim was to evaluate the safety and efficacy of electrical stimulation of the hippocampus in a long-term follow-up study, as well as its impact on memory performance in the treatment of patients with refractory mesial temporal lobe epilepsy. Methods: Nine patients were included. All had refractory partial complex seizures, some with secondary generalizations. All patients had a 3-month-baseline-seizure count, after which they underwent bilateral hippocampal diagnostic electrode implantation to establish focus laterality and location. Three patients had bilateral, and six, unilateral foci. Diagnostic electrodes were explanted and definitive Medtronic electrodes were implanted directed into the hippocampal foci. Position was confirmed with MRI and afterwards, the deep brain stimulation system internalized. Patients signed the informed consent approved by the Hospital's Ethics Committee and began a double-blind stimulation protocol. Patients attended a medical appointment every 3 months for seizure diary collection, deep brain stimulation system checkup, and neuropsychological testing. Results: Follow-up ranged from 18 months to 7 years. Patients were divided in two groups: five had normal MRIs and seizure reduction of >95%, while four had hippocampal sclerosis and seizure reduction of 50,70%. No patient had neuropsychological deterioration, nor did any patient show side effects. Three patients were explanted after 2 years due to skin erosion in the trajectory of the system. Conclusions: Electrical stimulation of the hippocampus provides a nonlesional method that improves seizure outcome without memory deterioration in patients with hippocampal epileptic foci. [source] Wada Memory Performance Predicts Seizure Outcome after Epilepsy Surgery in ChildrenEPILEPSIA, Issue 7 2003Gregory P. Lee Summary: Purpose: Wada memory asymmetries were examined in children from four comprehensive epilepsy surgery centers who subsequently underwent epilepsy surgery to determine whether Wada memory performance could predict degree of seizure relief in children. Methods: One hundred fifty-six children (between ages 5 and 16 years) with intractable epilepsy underwent Wada testing before resective epilepsy surgery (93 within the left hemisphere, and 63 within the right hemisphere). Memory stimuli were presented soon after intracarotid amobarbital injection, and recognition memory for the items was assessed after return to neurologic baseline. Eighty-eight children underwent unilateral temporal lobe resection, and 68 had extratemporal lobe resections. One hundred four (67%) children were seizure free (Engel class I), and 52 (33%) were not seizure free (Engel classes II,IV) at follow-up (mean follow-up interval, 2.3 years). Results: Seizure-free children recalled 19.3% more Wada memory items after ipsilateral injection than did non,seizure-free children (p = 0.008). If analysis was restricted to youngsters with temporal lobectomies (TLs), seizure-free children recalled 27.7% more items after ipsilateral injection than did non,seizure-free TL children (p = 0.004). With regard to individual patient prediction, 75% of children who had memory score asymmetries consistent with the seizure focus were seizure free. In contrast, only 56% of children whose memory score asymmetries were inconsistent with the seizure focus were seizure free (p = 0.01). Conclusions: Results suggest that Wada memory performance asymmetries are related to the degree of seizure relief after epilepsy surgery in children and adolescents. [source] Effects of dopamine-related gene,gene interactions on working memory component processesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2009Christine Stelzel Abstract Dopamine modulates complex cognitive functions like working memory and cognitive control. It is widely accepted that an optimal level of prefrontal dopamine supports working memory performance. In the present study we used a molecular genetic approach to test whether the optimal activity of the dopamine system for different component processes of working memory is additionally related to the availability of dopamine D2 receptors. We sought evidence for this assumption by investigating the interaction effect (epistasis) of variations in two dopaminergic candidate genes: the catechol- O -methyltransferase (COMT) Val158Met polymorphism, which has been shown to influence prefrontal dopamine concentration, and the DRD2/ANKK1-Taq-Ia polymorphism, which has been related to the density of D2 receptors. Our results show that COMT effects on working memory performance are modulated by the DRD2/ANKK1-TAQ-Ia polymorphism and the specific working memory component process under investigation. Val, participants , supposedly characterized by increased prefrontal dopamine concentrations , outperformed Val+ participants in the manipulation of working memory contents, but only when D2 receptor density could be considered to be high. No such effect was present for passive maintenance of working memory contents or for maintenance in the face of distracting information. This beneficial effect of a balance between prefrontal dopamine availability and D2 receptor density reveals the importance of considering epistasis effects and different working memory subprocesses in genetic association studies. [source] Basolateral amygdala inactivation by muscimol, but not ERK/MAPK inhibition, impairs the use of reward expectancies during working memoryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2007Lisa M. Savage Abstract Rats were trained on a delayed matching to position (DMTP) task that embedded either a differential outcomes procedure (DOP) or a non-differential outcomes procedure (NOP). The DOP, via Pavlovian conditioning (stimulus,outcome associations), results in the use of unique reward expectancies that facilitate learning and memory performance above subjects trained with a NOP that requires subjects to retain cue information for accurate choice behavior (stimulus,response associations). This enhancement in learning and/or memory produced by the DOP is called the differential outcomes effect (DOE). After being trained on the DMTP task, rats were implanted with two cannulae aimed at the basolateral amygdala (BLA) nuclei. Rats trained with the DOP, relative to those trained with the NOP, displayed enhanced short-term memory (STM) performance under vehicle conditions (i.e. the DOE). However, injections of the ,-aminobutyric acid (GABA)A agonist muscimol into the BLA dose-dependently (0.0625 and 0.125 µg) impaired STM performance only in DOP-trained rats. These results support the role of the BLA in the use of established reward expectancies during a short-term working memory task. Despite the fact that extracellular signal-regulated kinase/mitogen-activated protein kinases (ERK/MAPK) have been shown to be necessary for amygdala-dependent long-term potentiation and some forms of long-term and STM, inhibition of the ERK/MAPK signaling cascade by U0126 (2.0 or 4.0 µg) in the BLA was not critical for updating the STM of either spatial information or reward expectation. [source] Preparation and Memory Performance of a Nanoaggregated Dispersed Red 1-Functionalized Poly (N -vinylcarbazole) Film via Solution-Phase Self-AssemblyADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Xiao-Dong Zhuang Abstract A nanoaggregated dispersed red 1-grafted poly(N -vinylcarbazole) (abbreviated PVDR) is self-assembled via ,,, stacking interactions of the carbazole groups in the polymer system after adding a solution of PVDR in N,N -dimethylformamide to dichloromethane. Upon self-assembly, the nanoaggregated PVDR film displays helical columnar stacks with large grain sizes, whereas a non-aggregated PVDR film exhibits an amorphous morphology with smaller grain size. A write-once read-many-times (WORM) memory device is shown whereby a pre-assembled solution of PVDR is spin-coated as the active layer and is sandwiched between an aluminum electrode and an indium-tin-oxide (ITO) electrode. This device shows very good memory performance, with an ON/OFF current ratio of more than 105 and a low misreading rate through the precise control of the ON and OFF states. The stability of the nanoaggregated PVDR device is much higher than that of the non-nanoaggregated PVDR device. This difference in device stability under constant voltage stress can be mainly attributed to the difference in the film crystallinity and surface morphology. No degradation in current density was observed for the ON- and OFF-states after more than one hundred million (108) continuous read cycles indicating that both states were insensitive to the read cycles. These results render the nanoaggregated PVDR polymer as promising components for high-performance polymer memory devices. [source] Comparison of single vs. multiple administrations of the AMPA receptors modulator S 18986 in the object recognition task in ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2007V. Bertaina-Anglade Abstract The present study aimed at defining the best scheme of administration of the , -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-positive modulator (S)-2,3-dihydro-[3,4]-cyclopentano-1,2,4-benzothiadiazine-1,1-dioxide (S 18986) [once daily (o.d.) administration of 1 mg/kg for 3 days vs. three times daily (t.i.d.) administration of 0.3 mg/kg for 3 days] to get an optimal procognitive activity in the object recognition task in rats. Memory performance [Recognition Index (RI)] of rats was significantly improved 1 h (RI = 41%, P < 0.01) and 3 h (RI = 46%, P < 0.001) following oral administration of S 18986 (1 mg/kg, o.d.) when compared with animals receiving the vehicle (RI = 6%). When the interval between administration and testing was increased to 6 h and 9 h, no statistically significant improvement in memory performance was observed (RI = 42% for 6 h and RI = 18% for 9 h vs. 20% for the vehicle group). When S 18986 was administered at 0.3 mg/kg t.i.d., no statistically significant improvement in memory performance was observed (RI = 36%). These findings show a long-lasting efficacy of the AMPA receptor allosteric modulator in the object recognition task despite a short half-life in plasma and in brain (approximately 1 h). Accordingly, multiple administrations of S 18986 are not required to obtain a maximal efficacy in this paradigm, because a o.d. schedule of administration leads to a powerful procognitive activity. [source] Influence of predator stress on the consolidation versus retrieval of long-term spatial memory and hippocampal spinogenesisHIPPOCAMPUS, Issue 7 2006David M. Diamond Abstract We have studied the influence of predator stress (30 min of cat exposure) on long-term (24 h) spatial memory and the density of spines in basilar dendrites of CA1 neurons. Predator stress occurred either immediately before water maze training (Stress Pre-Training) or before the 24 h memory test (Stress Pre-Retrieval). The Control (nonstress) group exhibited excellent long-term spatial memory and a robust increase in the density of stubby, but not mushroom, shaped spines. The Stress Pre-Training group had impaired long-term memory and did not exhibit any changes in spine density. The Stress Pre-Retrieval group was also impaired in long-term memory performance, but this group exhibited an increase in the density of stubby, but not mushroom, shaped spines, which was indistinguishable from the control group. These findings indicate that: (1) A single day of water maze training under control conditions produced intact long-term memory and an increase in the density of stubby spines in CA1; (2) Stress before training interfered with the consolidation of information into long-term memory and suppressed the training-induced increase in spine density; and (3) Stress immediately before the 24 h memory test trial impaired the retrieval of the stored memory, but did not reverse the training-induced increase in CA1 spine density. Overall, this work provides evidence of structural plasticity in dendrites of CA1 neurons which may be involved in the consolidation process, and how spinogenesis and memory are modulated by stress. © 2006 Wiley-Liss, Inc. [source] Somatosensory working memory performance in humans depends on both engagement and disengagement of regions in a distributed networkHUMAN BRAIN MAPPING, Issue 1 2010Saskia Haegens Abstract Successful working memory (WM) requires the engagement of relevant brain areas but possibly also the disengagement of irrelevant areas. We used magnetoencephalography (MEG) to elucidate the temporal dynamics of areas involved in a somatosensory WM task. We found an increase in gamma band activity in the primary and secondary somatosensory areas during encoding and retention, respectively. This was accompanied by an increase of alpha band activity over task-irrelevant regions including posterior and ipsilateral somatosensory cortex. Importantly, the alpha band increase was strongest during successful WM performance. Furthermore, we found frontal gamma band activity that correlated both with behavioral performance and the alpha band increase. We suggest that somatosensory gamma band activity reflects maintenance and attention-related components of WM operations, whereas alpha band activity reflects frontally controlled disengagement of task-irrelevant regions. Our results demonstrate that resource allocation involving the engagement of task-relevant and disengagement of task-irrelevant regions is needed for optimal task execution. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] Decreased basal fMRI functional connectivity in epileptogenic networks and contralateral compensatory mechanismsHUMAN BRAIN MAPPING, Issue 5 2009Gaelle Bettus Abstract A better understanding of interstructure relationship sustaining drug-resistant epileptogenic networks is crucial for surgical perspective and to better understand the consequences of epileptic processes on cognitive functions. We used resting-state fMRI to study basal functional connectivity within temporal lobes in medial temporal lobe epilepsy (MTLE) during interictal period. Two hundred consecutive single-shot GE-EPI acquisitions were acquired in 37 right-handed subjects (26 controls, eight patients presenting with left and three patients with right MTLE). For each hemisphere, normalized correlation coefficients were computed between pairs of time-course signals extracted from five regions involved in MTLE epileptogenic networks (Brodmann area 38, amygdala, entorhinal cortex (EC), anterior hippocampus (AntHip), and posterior hippocampus (PostHip)). In controls, an asymmetry was present with a global higher connectivity in the left temporal lobe. Relative to controls, the left MTLE group showed disruption of the left EC-AntHip link, and a trend of decreased connectivity of the left AntHip-PostHip link. In contrast, a trend of increased connectivity of the right AntHip-PostHip link was observed and was positively correlated to memory performance. At the individual level, seven out of the eight left MTLE patients showed decreased or disrupted functional connectivity. In this group, four patients with left TLE showed increased basal functional connectivity restricted to the right temporal lobe spared by seizures onset. A reverse pattern was observed at the individual level for patients with right TLE. This is the first demonstration of decreased basal functional connectivity within epileptogenic networks with concomitant contralateral increased connectivity possibly reflecting compensatory mechanisms. Hum Brain Mapp 2009. © 2008 Wiley-Liss, Inc. [source] Verbal memory performance improved via an acute administration of D -amphetamineHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 5 2007Inge Zeeuws Abstract Background An improved long-term retention of verbal memory was observed after an acute D -amphetamine administration. It was proposed that D -amphetamine modulates consolidation, but a possible drug effect on retrieval could not be rejected. Objectives We want to provide additional support for the consolidation hypothesis, and investigate whether an influence on intervening retrieval can be refuted. Methods Thirty-six male paid volunteers participated in a double blind, counterbalanced, placebo-controlled design in which the number of intermediate free recall tests was manipulated. Results A significant D -amphetamine facilitation effect on recall performance emerged 1 h and 1 day after list learning. In line with the consolidation hypothesis, no effect was found on immediate tests. Importantly, the number of intermediate retrievals did not affect the magnitude of the drug effect, suggesting that the D -amphetamine facilitation effect is independent of retrieval. Conclusion The D -amphetamine facilitation effect on verbal memory does not involve a modulation of the initial encoding or short-term memory (STM) processes. Moreover, the drug does not enhance long-term retention by acting on intervening retrieval processes. The current findings are in line with the conjecture of an involvement of the consolidation process in the D -amphetamine facilitation effect on verbal memory in healthy humans. Copyright © 2007 John Wiley & Sons, Ltd. [source] Acute cognitive effects of standardised Ginkgo biloba extract complexed with phosphatidylserineHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 4 2007D. O. Kennedy Abstract Recent data suggest that the complexation of standardised Ginkgo biloba extract (GBE) with soy-derived phospholipids enhances the bio-availablity of GBE's active components. The current study therefore aimed to assess the comparative cognitive and mood effects of a low dose of GBE and products complexing the same extract with either phosphatidylserine or phosphatidylcholine. The study utilised a placebo-controlled, multi-dose, double-blind, balanced-crossover design. Twenty-eight healthy young participants received 120,mg GBE, 120,mg GBE complexed with phosphatidylserine (VirtivaÔ), 120,mg GBE complexed with phosphatidylcholine and a matching placebo, on separate days 7 days apart. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery and Serial Subtraction tasks immediately prior to dosing and at 1, 2.5, 4 and 6,h thereafter. The primary outcome measures were the four aspects of cognitive performance, which have previously been derived by factor analysis of CDR subtests. Levels of terpenoids (bilobalide, ginkgolide A and ginkgolide B) were concomitantly assessed in plasma samples taken pre-dose and at 3 and 6.5,h post-dose. In keeping with previous research utilising the same methodology, 120,mg of GBE was not associated with markedly improved performance on the primary outcomes. However, administration of GBE complexed with phosphatidylserine resulted both in improved secondary memory performance and significantly increased speed of memory task performance across all of the post-dose testing sessions. Enhancement following GBE complexed with phosphatidylcholine was restricted to a modest improvement in secondary memory performance which was restricted to one post-dose time point. All three treatments were associated with improved calmness. There were no significant differences in post-dose levels of terpenoids between the Ginkgo containing treatments, although this latter finding may be attributable to methodological factors. Complexation with phosphatidylserine appears to potentiate the cognitive effects associated with a low dose of GBE. Further research is required to identify whether this effect is due to the complexation of the extracts, their mere combination, or the separate psychopharmacological actions of the two extracts. Copyright © 2007 John Wiley & Sons, Ltd. [source] Visuo-spatial working memory deficits in current and former users of MDMA (,ecstasy')HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 2 2005Michelle Wareing Abstract Verbal working memory and executive deficits have been observed in ecstasy users. The present study sought to establish whether these also extended to visuo-spatial working memory. Thirty-six current ecstasy users, 12 former users (abstinent for at least 6 months) and 31 individuals that had never used ecstasy were tested on a maintenance plus type visuo-spatial working memory task. The task required participants to recall a sequence of specially marked cells in a four-by-four matrix display while at the same time performing a concurrent visual judgement task. Both the current and former user groups registered impairments relative to nonusers. These remained significant following statistical controls for a range of potentially confounding variables including the use of various other drugs during the 3 months prior to testing. Users were unimpaired on a simple spatial span measure suggesting that the deficits observed reflected the executive aspects of the spatial working memory task. Also consistent with executive involvement, statistical controls for measures of verbal working memory performance (computation span) removed half of the ecstasy-related variance in spatial working memory. The possibility that the pattern of results obtained might reflect some general impairment in information processing efficiency is discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Caffeine (4,mg/kg) influences sustained attention and delayed free recall but not memory predictionsHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 4 2001William L. Kelemen Abstract This experiment was conducted to examine the influence of a moderate dose of caffeine (4,mg/kg) on delayed memory, metamemory, and sustained attention. One hundred and forty-two volunteers ingested either caffeine or placebo during a study session which included three different memory tasks (free recall, cued recall, and recognition), and they made predictions of future memory performance. On day 2, participants again ingested either caffeine or placebo and completed memory tests. Sustained attention performance was measured on both days, and caffeine reliably improved hit rates and response latencies. A reliable drug-state interaction was detected only in the free recall test of memory. Caffeine did not affect the magnitude or accuracy of memory predictions, but there was some evidence that expectancies about caffeine were related to cognitive performance. Overall, caffeine's impact on memory and metamemory was not robust in this study. Copyright © 2001 John Wiley & Sons, Ltd. [source] Stress and hippocampal plasticity: implications for the pathophysiology of affective disordersHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue S1 2001Bruce S. McEwen Abstract The hippocampal formation, a structure involved in declarative, spatial and contextual memory, is a particularly sensitive and vulnerable brain region to stress and stress hormones. The hippocampus shows a considerable degree of structural plasticity in the adult brain. Stress suppresses neurogenesis of dentate gyrus granule neurons, and repeated stress causes atrophy of dendrites in the CA3 region. In addition, ovarian steroids regulate synapse formation during the estrous cycle of female rats. All three forms of structural remodeling of the hippocampus are mediated by hormones working in concert with excitatory amino acids (EAA) and N -methyl- D -aspartate (NMDA) receptors. EAA and NMDA receptors are also involved in neuronal death that is caused in pyramidal neurons by seizures and by ischemia and prolonged psychosocial stress. In the human hippocampus, magnetic resonance imaging studies have shown that there is a selective atrophy in recurrent depressive illness, accompanied by deficits in memory performance. Hippocampal atrophy may be a feature of affective disorders that is not treated by all medications. From a therapeutic standpoint, it is essential to distinguish between permanent damage and reversible atrophy in order to develop treatment strategies to either prevent or reverse deficits. In addition, remodeling of brain cells may occur in other brain regions. Possible treatments are discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Neural Correlates of Encoding Predict Infants' Memory in the Paired-Comparison ProcedureINFANCY, Issue 3 2010Kelly A. Snyder The present study used event-related potentials (ERPs) to monitor infant brain activity during the initial encoding of a previously novel visual stimulus, and examined whether ERP measures of encoding predicted infants' subsequent performance on a visual memory task (i.e., the paired-comparison task). A late slow wave component of the ERP measured at encoding predicted infants' immediate performance in the paired-comparison task: amplitude of the late slow wave at right-central and temporal leads decreased with stimulus repetition, and greater decreases at right-anterior-temporal leads during encoding were associated with better memory performance at test. By contrast, neither the amplitude nor latency of the negative central (Nc) component predicted infants' subsequent performance in the paired-comparison task. These findings are discussed with respect to a biased competition model of visual attention and memory. [source] Maternal distancing and event memory at 20 monthsINFANT AND CHILD DEVELOPMENT, Issue 4 2003Nathalie Prudhomme Abstract Maternal distancing strategies (Sigel, 1993 in The Development and Meaning of Psychological Distance, Cocking R, Renninger KA (eds). Erlbaum: Hillsdale, NJ; 141,158) with 20-month-olds were analysed during a mother,child interaction in a free play situation. Then, they were related to memory performance of the children as assessed by the elicited imitation paradigm with 4 three-step sequences of actions (Bauer, Hertsgaard, Child Dev. 1993; 64:1204). The aim of this work was to (1) confirm that the Sigel's model of distancing could be used with very young children under two; (2) study relationships between maternal distancing that stimulate representational competence of the child and memory performance of the children. Results showed two different patterns of correlations depending on the sequence type: for enabling sequences, significant positive correlations were obtained for the first two distancing levels whereas for arbitrary sequences no correlation was found whatever the distancing level. As discussed, the first pattern brings new arguments in support of declarative memory before the age of 2 years and reframes the memory development in a Vygotskyian interactionist perspective. The second pattern of correlations calls for replication and more investigation about the processes implied in memory of very young children for different sequence types. Copyright © 2003 John Wiley & Sons, Ltd. [source] Depression, cognitive reserve and memory performance in older adultsINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 7 2010Mike Murphy Abstract Objectives The purpose of this research study was to examine the relationship between education and leisure, as markers of cognitive reserve, depressive symptoms and memory performance in a sample of cognitively normal Irish older adults. Methods A cross-sectional survey style design was employed to gather data. A sample of 121 older adults in the Cork area was recruited through publicly advertising for volunteers. Only those volunteers who obtained a score of greater than 23 on the MMSE, and were not taking antidepressant or anxiolytic medications, were included. Data from 99 participants were included in the analysis. Results Controlling for age and gender, depressive symptoms were found to be associated with poorer immediate recall performance, while greater than 12 years of education was positively associated with delayed recall and savings. Leisure did not emerge as being associated with any of the dimensions of memory assessed. Conclusions Depressive symptoms emerged as associated with immediate recall, even though few of the participants met the cut-off for caseness. This may indicate a need for intervention in cases of subclinical depression with associated memory complaints. The association between education level and both delayed recall and savings provides support for the cognitive reserve hypothesis, and may suggest useful non-pharmacological approaches to memory deficits in later life. Copyright © 2009 John Wiley & Sons, Ltd. [source] Neural correlates of verbal episodic memory in patients with MCI and Alzheimer's disease,,a VBM studyINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 11 2008Dirk T. Leube Abstract Objective The hippocampus is a key area for episodic memory processes. Hippocampal atrophy is a hallmark feature of Alzheimer's disease (AD). We used a new and automatized morphometric technique to better characterize brain atrophy in subjects with different levels of cognitive deficit. Methods In this study 21 participants with Mild Cognitive Impairment (MCI), 12 patients with early AD and 29 elderly control subjects were subjected to high resolution MRI and a neuropsychological test battery. Brain volume across participants, measured by voxel-based morphometry (VBM), was correlated with verbal memory capacity, measured with a verbal memory test (VLMT). Results Atrophy in the anterior hippocampus, the ento- and perirhinal cortex as well as the parahippocampal gyrus, middle temporal gyrus and anterior cingulate cortex correlated closely with episodic memory performance. Conclusions These brain areas are known to subserve episodic encoding of verbal material. The data contribute to a better understanding of atrophic brain processes in subjects at risk for AD. A combination of neuropsychological testing and voxel-based morphometry may serve as a diagnostic tool in the future. Copyright © 2008 John Wiley & Sons, Ltd. [source] Choosing words at the study phase: The self-choice effect on memory from the viewpoint of connective processing1JAPANESE PSYCHOLOGICAL RESEARCH, Issue 1 2003Tetsuji Hirano Abstract: The self-choice effect, that is the superior memory performance observed when participants are allowed to choose the item at the study phase than when they are not (lack of choice), has been explained by the encoding-strategy hypothesis (Takahashi, 1997). This hypothesis distinguishes between organizational processing, which focuses upon the relationship between chosen items, and item-speci,c processing, which itself focuses on the elements that make the chosen item distinctive. The encoding-strategy hypothesis predicts that the ability for the successive recall of chosen items can be affected by organized list (Experiment 1). The results of our experiments ran counter to the prediction and were interpreted by a new concept called connective processing, which would emphasize the relationship of paired items. Connective processing was examined through orienting tasks (Experiment 2). The results were more suitably interpreted by connective than organizational processing. [source] | |||||||||||||||||||||||||||||||||||||