151
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Demeter DV, Davis SE. Procrastination as a Tool: Exploring Unconventional Components of Academic Success. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ce.2013.47a2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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152
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Dockery CA. The Human Experiment: How We Won’t Win the Rat Race. What Can We Learn from Brain Stimulation in Humans and Rats About Enhancing the Functional Neurobiology of Higher Cognitive Functions? TRENDS IN AUGMENTATION OF HUMAN PERFORMANCE 2013. [DOI: 10.1007/978-94-007-6253-4_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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153
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Cornwell BR, Arkin N, Overstreet C, Carver FW, Grillon C. Distinct contributions of human hippocampal theta to spatial cognition and anxiety. Hippocampus 2012; 22:1848-59. [PMID: 22467298 PMCID: PMC3390451 DOI: 10.1002/hipo.22019] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2012] [Indexed: 11/06/2022]
Abstract
Current views of the hippocampus assign this structure, and its prominent theta rhythms, a key role in both cognition and affect. We studied this duality of function in humans, where no direct evidence exists. Whole-head magnetoencephalographic (MEG) data were recorded to measure theta activity while healthy participants (N = 25) navigated two virtual Morris water mazes, one in which they risked receiving aversive shocks without warning to induce anxiety and one in which they were safe from shocks. Results showed that threat of shock elevated anxiety level and enhanced navigation performance as compared to the safe condition. MEG source analyses revealed that improved navigation performance during threat was preferentially associated with increased left septal (posterior) hippocampal theta (specifically 4-8 Hz activity), replicating previous research that emphasizes a predominant role of the septal third of the hippocampus in spatial cognition. Moreover, increased self-reported anxiety during threat was preferentially associated with increased left temporal (anterior) hippocampal theta (specifically 2-6 Hz activity), consistent with this region's involvement in mediating conditioned and innate fear. Supporting contemporary theory, these findings highlight simultaneous involvement of the human hippocampus in spatial cognition and anxiety, and clarify their distinct correlates.
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Affiliation(s)
- Brian R Cornwell
- Section on Neurobiology of Fear and Anxiety, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA.
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154
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Yau JLW, Seckl JR. Local amplification of glucocorticoids in the aging brain and impaired spatial memory. Front Aging Neurosci 2012; 4:24. [PMID: 22952463 PMCID: PMC3430012 DOI: 10.3389/fnagi.2012.00024] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 08/02/2012] [Indexed: 12/24/2022] Open
Abstract
The hippocampus is a prime target for glucocorticoids (GCs) and a brain structure particularly vulnerable to aging. Prolonged exposure to excess GCs compromises hippocampal electrophysiology, structure, and function. Blood GC levels tend to increase with aging and correlate with impaired spatial memory in aging rodents and humans. The magnitude of GC action within tissues depends not only on levels of steroid hormone that enter the cells from the periphery and the density of intracellular receptors but also on the local metabolism of GCs by 11β-hydroxysteroid dehydrogenases (11β-HSD). The predominant isozyme in the adult brain, 11β-HSD1, locally regenerates active GCs from inert 11-keto forms thus amplifying GC levels within specific target cells including in the hippocampus and cortex. Aging associates with elevated hippocampal and neocortical 11β-HSD1 and impaired spatial learning while deficiency of 11β-HSD1 in knockout (KO) mice prevents the emergence of cognitive decline with age. Furthermore, short-term pharmacological inhibition of 11β-HSD1 in already aged mice reverses spatial memory impairments. Here, we review research findings that support a key role for GCs with special emphasis on their intracellular regulation by 11β-HSD1 in the emergence of spatial memory deficits with aging, and discuss the use of 11β-HSD1 inhibitors as a promising novel treatment in ameliorating/improving age-related memory impairments.
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Affiliation(s)
- Joyce L W Yau
- Centre for Cognitive Ageing and Cognitive Epidemiology and Endocrinology Unit, Centre for Cardiovascular Science, The Queen's Medical Research Institute, University of Edinburgh Edinburgh, UK
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155
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Personality traits in rats predict vulnerability and resilience to developing stress-induced depression-like behaviors, HPA axis hyper-reactivity and brain changes in pERK1/2 activity. Psychoneuroendocrinology 2012; 37:1209-23. [PMID: 22240307 DOI: 10.1016/j.psyneuen.2011.12.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 12/14/2011] [Accepted: 12/14/2011] [Indexed: 01/24/2023]
Abstract
Emerging evidence indicates that certain behavioral traits, such as anxiety, are associated with the development of depression-like behaviors after exposure to chronic stress. However, single traits do not explain the wide variability in vulnerability to stress observed in outbred populations. We hypothesized that a combination of behavioral traits might provide a better characterization of an individual's vulnerability to prolonged stress. Here, we sought to determine whether the characterization of relevant behavioral traits in rats could aid in identifying individuals with different vulnerabilities to developing stress-induced depression-like behavioral alterations. We also investigated whether behavioral traits would be related to the development of alterations in the hypothalamic-pituitary-adrenal axis and in brain activity - as measured through phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2)--in response to an acute stressor following either sub-chronic (2 weeks) or chronic (4 weeks) unpredictable stress (CUS). Sprague-Dawley rats were characterized using a battery of behavioral tasks, and three principal traits were identified: anxiety, exploration and activity. When combined, the first two traits were found to explain the variability in the stress responses. Our findings confirm the increased risk of animals with high anxiety developing certain depression-like behaviors (e.g., increased floating time in the forced swim test) when progressively exposed to stress. In contrast, the behavioral profile based on combined low anxiety and low exploration was resistant to alterations related to social behaviors, while the high anxiety and low exploration profile displayed a particularly vulnerable pattern of physiological and neurobiological responses after sub-chronic stress exposure. Our findings indicate important differences in animals' vulnerability and/or resilience to the effects of repeated stress, particularly during initial or intermediate levels of stress exposure, and they highlight that the behavioral inhibition profile of an animal provides a particular susceptibility to responding in a deleterious manner to stress.
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156
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Xu X, Zhou X, Zhou XW, Zhang Z, Liao MJ, Gao Q, Luo HM. Schizandrin prevents dexamethasone-induced cognitive deficits. Neurosci Bull 2012; 28:532-40. [PMID: 22961473 DOI: 10.1007/s12264-012-1258-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 06/04/2012] [Indexed: 12/23/2022] Open
Abstract
OBJECTIVE To model glucocorticoid-induced cognitive impairment and evaluate the neuroprotection by schizandrin (Sch) against dexamethasone (Dex)-induced neurotoxicity in vivo and in vitro. METHODS Cerebral cortical cells from neonatal Sprague-Dawley rats (within 24 hours after birth) were cultured for 9 days, and then treated with Dex (10(-4), 10(-5), 10(-6) or 10(-7) mol/L) for 24 h or pretreated with 10(-4) mol/L Dex for 24 h followed by 10, 20, 40, or 80 μmol/L Sch for 48 h. Cell viability was assessed using the MTT assay. Immunofluorescence and real-time PCR for MAP2 were performed to confirm the effects of Dex on neurite outgrowth. In vivo, kunming mice were randomly divided into six groups: control [(intragastric (i.g.) vehicle for 42 days]; Dex group I (5 mg/kg · d(-1) Dex i.g. treatment for 28 days followed by i.g. vehicle for 14 days); Dex group II (Dex i.g. for 42 days); Dex + Sch (Dex i.g. for 28 days followed by 5, 15, or 45 mg/kg · d(-1) Sch i.g. for 14 days). Learning and memory were assessed by Morris water maze test. Histological examination was used to assess pathology and apoptosis in neurons. RESULTS Compared to the Dex groups, Sch increased cell viability in a dose-dependent manner, improved performance in the Morris water maze and ameliorated the morphological changes. CONCLUSION Sch has neuroprotective effects against insults induced by glucocorticoid.
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Affiliation(s)
- Xiao Xu
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou, 510632, China
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157
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Prevention of stress-impaired fear extinction through neuropeptide s action in the lateral amygdala. Neuropsychopharmacology 2012; 37:1588-99. [PMID: 22298122 PMCID: PMC3358750 DOI: 10.1038/npp.2012.3] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Stressful and traumatic events can create aversive memories, which are a predisposing factor for anxiety disorders. The amygdala is critical for transforming such stressful events into anxiety, and the recently discovered neuropeptide S transmitter system represents a promising candidate apt to control these interactions. Here we test the hypothesis that neuropeptide S can regulate stress-induced hyperexcitability in the amygdala, and thereby can interact with stress-induced alterations of fear memory. Mice underwent acute immobilization stress (IS), and neuropeptide S and a receptor antagonist were locally injected into the lateral amygdala (LA) during stress exposure. Ten days later, anxiety-like behavior, fear acquisition, fear memory retrieval, and extinction were tested. Furthermore, patch-clamp recordings were performed in amygdala slices prepared ex vivo to identify synaptic substrates of stress-induced alterations in fear responsiveness. (1) IS increased anxiety-like behavior, and enhanced conditioned fear responses during extinction 10 days after stress, (2) neuropeptide S in the amygdala prevented, while an antagonist aggravated, these stress-induced changes of aversive behaviors, (3) excitatory synaptic activity in LA projection neurons was increased on fear conditioning and returned to pre-conditioning values on fear extinction, and (4) stress resulted in sustained high levels of excitatory synaptic activity during fear extinction, whereas neuropeptide S supported the return of synaptic activity during fear extinction to levels typical of non-stressed animals. Together these results suggest that the neuropeptide S system is capable of interfering with mechanisms in the amygdala that transform stressful events into anxiety and impaired fear extinction.
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158
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Kennedy PJ, Clarke G, Quigley EMM, Groeger JA, Dinan TG, Cryan JF. Gut memories: towards a cognitive neurobiology of irritable bowel syndrome. Neurosci Biobehav Rev 2012; 36:310-40. [PMID: 21777613 DOI: 10.1016/j.neubiorev.2011.07.001] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/30/2011] [Accepted: 07/04/2011] [Indexed: 01/06/2023]
Abstract
The brain and the gut are engaged in continual crosstalk along a number of pathways collectively termed the 'brain-gut axis'. Over recent years it has become increasingly clear that dysregulation of the axis at a number of levels can result in disorders such as irritable bowel syndrome (IBS). With recent advances in neuroimaging technologies, insights into the neurobiology of IBS are beginning to emerge. However the cognitive neurobiology of IBS has remained relatively unexplored to date. In this review we summarise the available data on cognitive function in IBS. Moreover, we specifically address three key pathophysiological factors, namely; stress, immune activation and chronic pain, together with other factors involved in the manifestation of IBS, and explore how each of these components may impact centrally, what neurobiological mechanisms might be involved, and consider the implications for cognitive functioning in IBS. We conclude that each factor addressed could significantly impinge on central nervous system function, supporting the view that future research efforts must be directed towards a detailed assessment of cognitive function in IBS.
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Affiliation(s)
- Paul J Kennedy
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
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159
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Visuo-spatial path learning, stress, and cortisol secretion following military cadets' first parachute jump: the effect of increasing task complexity. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2011; 11:332-43. [PMID: 21607782 DOI: 10.3758/s13415-011-0043-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The present field experiment examined how multi-trial visuo-spatial learning and memory performance are impacted by excessive arousal, instigated by a potentially life-threatening event (i.e., a first parachute jump). Throughout a parachute training activity, subjective and neuroendocrine (i.e., cortisol) stress levels were assessed of 61 male military cadets who were randomly assigned to a control (n = 30) or a jump stress condition (n = 31). Post-stress learning and memory capacity was assessed with a 10-trial path-learning task that permitted emergence of learning curves. Pre-activity cortisol concentrations indicated a significant neuroendocrine anticipatory stress response in the stress group. Following parachuting, subjective stress levels and salivary cortisol reactivity differed significantly between groups. Visuo-spatial path-learning performance was impaired significantly after jump stress exposure, relative to the control group. Moreover, examination of the learning curves showed similar learning and memory performance at onset of the trials, with curves bifurcating as the task became more complex. These findings are in accordance with leading theories that acknowledge a moderating effect of task complexity. In sum, the present study extends knowledge concerning anticipatory stress effects, endogenously instigated cortisol reactivity, and the influence of extreme arousal on visuo-spatial path learning.
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160
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Weinstock M. Sex-dependent changes induced by prenatal stress in cortical and hippocampal morphology and behaviour in rats: an update. Stress 2011; 14:604-13. [PMID: 21790452 DOI: 10.3109/10253890.2011.588294] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Recent prospective studies have shown that gestational stress in humans is more likely to cause cognitive and emotional problems in the offspring if it occurs during weeks 12-20 of pregnancy. There are also suggestions that such problems may be gender dependent. This review describes recent studies that found sex differences in the behaviour and brain morphology of rats stressed prenatally during the equivalent period of neuronal development in humans. Learning deficits are more prevalent in males and anxious behaviour in females but their appearance depends also on the timing and intensity of the stress and the age when the offspring were tested. Cognitive deficits and anxiety are linked to a sex-dependent reduction in neurogenesis and in measures of dendritic morphology in the prefrontal cortex and hippocampal formation. Maternal adrenalectomy prior to the stress prevents the anxiety in both sexes and learning deficits in males. Corticosterone administration to the dam to mimic levels induced by stress reinstates only the anxiety, indicating that it arises from foetal exposure to corticosterone from the maternal circulation. Learning deficits in males may result from a combination of a reduction in testosterone and in aromatase activity, together with the action of other adrenal hormones.
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Affiliation(s)
- M Weinstock
- Department of Pharmacology, Institute of Drug Research, Hebrew University Medical Centre, Ein Kerem, Jerusalem, Israel.
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161
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Caroprese M, Napolitano F, Boivin X, Albenzio M, Annicchiarico G, Sevi A. Development of affinity to the stockperson in lambs from two breeds. Physiol Behav 2011; 105:251-6. [PMID: 21903124 DOI: 10.1016/j.physbeh.2011.08.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 08/18/2011] [Accepted: 08/24/2011] [Indexed: 10/17/2022]
Abstract
The interactions between genetic and environmental factors on the development of lamb affinity to humans was assessed on 48 animals from two breeds (Gentile di Puglia and Comisana) and two treatments (Gentled and Not Gentled) producing 4 groups (GPg, GPng, Cg, Cng, respectively). The Gentile di Puglia and Comisana gentled animals were subjected to a period of training consisting of gently handling each lamb for 5 min three times a day for the first week and then twice a week for three additional weeks. The gentling procedure included both tactile and visual/auditory interactions. At 30-32 days of age lambs were subjected to three arena tests conducted in a novel environment: i) isolation test (each animal was exposed to a novel environment, and isolated from tactile and visual contact with conspecifics for 5 min), ii) stationary human test (as previously but a human sitting in a corner of the pen), and iii) pen-mates' test (each animal was tested in the presence of 2 pen-mates whose behaviour was not recorded). During the 13 training sessions lambs exhibited an increasing number of contacts with the human and a decreasing number of bleats (P<0.001), although Gentile di Puglia lambs interacted more with the human (P<0.001) and tended to bleat less (P<0.10) than Comisana lambs. Lambs vocalised more and climbed more when tested in isolation as compared with lambs tested either with the human or with the pen-mates (P<0.01) and they vocalised more in the presence of the human than with the pen-mates (P<0.001). A higher number of contacts with the human stimulus was observed in gentled animals (P<0.05). However, differences between gentled and not gentled animals were only significant in Gentile di Puglia subjects (P<0.01). GPng lambs displayed the longest ambulatory activity during the isolation test (P<0.05) and exhibited more climbing attempts during the isolation test as compared with the human or the pen-mates' tests (P<0.001). A higher cortisol level was shown by GPng lambs in comparison with Cng subjects during the stationary human test (P<0.01), whereas no differences were detected between the two gentled groups. Gentling determined an improvement of the quality of human animal relationship in more reactive breeds such as Gentile di Puglia sheep.
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Affiliation(s)
- M Caroprese
- Dipartimento PRIME, Università degli Studi di Foggia, via Napoli, 25, 71100 Foggia, Italy
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162
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Stress effects on memory: an update and integration. Neurosci Biobehav Rev 2011; 36:1740-9. [PMID: 21771612 DOI: 10.1016/j.neubiorev.2011.07.002] [Citation(s) in RCA: 477] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 06/30/2011] [Accepted: 07/03/2011] [Indexed: 11/21/2022]
Abstract
It is well known that stressful experiences may affect learning and memory processes. Less clear is the exact nature of these stress effects on memory: both enhancing and impairing effects have been reported. These opposite effects may be explained if the different time courses of stress hormone, in particular catecholamine and glucocorticoid, actions are taken into account. Integrating two popular models, we argue here that rapid catecholamine and non-genomic glucocorticoid actions interact in the basolateral amygdala to shift the organism into a 'memory formation mode' that facilitates the consolidation of stressful experiences into long-term memory. The undisturbed consolidation of these experiences is then promoted by genomic glucocorticoid actions that induce a 'memory storage mode', which suppresses competing cognitive processes and thus reduces interference by unrelated material. Highlighting some current trends in the field, we further argue that stress affects learning and memory processes beyond the basolateral amygdala and hippocampus and that stress may pre-program subsequent memory performance when it is experienced during critical periods of brain development.
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163
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Neural mechanisms and computations underlying stress effects on learning and memory. Curr Opin Neurobiol 2011; 21:502-8. [DOI: 10.1016/j.conb.2011.03.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 02/08/2011] [Accepted: 03/25/2011] [Indexed: 11/22/2022]
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164
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Branchi I, Karpova NN, D’Andrea I, Castrén E, Alleva E. Epigenetic modifications induced by early enrichment are associated with changes in timing of induction of BDNF expression. Neurosci Lett 2011; 495:168-72. [DOI: 10.1016/j.neulet.2011.03.038] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/03/2011] [Accepted: 03/11/2011] [Indexed: 01/20/2023]
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165
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Sandi C. Glucocorticoids act on glutamatergic pathways to affect memory processes. Trends Neurosci 2011; 34:165-76. [PMID: 21377221 DOI: 10.1016/j.tins.2011.01.006] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Revised: 01/24/2011] [Accepted: 01/24/2011] [Indexed: 12/22/2022]
Abstract
Glucocorticoids can acutely affect memory processes, with both facilitating and impairing effects having been described. Recent work has revealed that glucocorticoids may affect learning and memory processes by interacting with glutamatergic mechanisms. In this opinion article I describe different glutamatergic pathways that glucocorticoids can affect to modulate memory processes. Furthermore, glucocorticoid-glutamatergic interactions during information processing are proposed as a potential model to explain many of the diverse actions of glucocorticoids on cognition. The model suggests that direct modulation of glutamatergic pathways by glucocorticoids could serve as an important mechanism for these hormones to directly alter cognitive functions.
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Affiliation(s)
- Carmen Sandi
- Laboratory of Behavioral Genetics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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