551
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Computerized video analysis of social interactions in mice. Nat Methods 2012; 9:410-7. [PMID: 22388289 DOI: 10.1038/nmeth.1924] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 02/10/2012] [Indexed: 12/13/2022]
Abstract
The study of social interactions in mice is used as a model for normal and pathological cognitive and emotional processes. But extracting comprehensive behavioral information from videos of interacting mice is still a challenge. We describe a computerized method and software, MiceProfiler, that uses geometrical primitives to model and track two mice without requiring any specific tagging. The program monitors a comprehensive repertoire of behavioral states and their temporal evolution, allowing the identification of key elements that trigger social contact. Using MiceProfiler we studied the role of neuronal nicotinic receptors in the establishment of social interactions and risk-prone postures. We found that the duration and type of social interactions with a conspecific evolves differently over time in mice lacking neuronal nicotinic receptors (Chrnb2-/-, here called β2(-/-)), compared to C57BL/6J mice, and identified a new type of coordinated posture, called back-to-back posture, that we rarely observed in β2(-/-) mice.
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552
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Tomasi D, Volkow ND. Abnormal functional connectivity in children with attention-deficit/hyperactivity disorder. Biol Psychiatry 2012; 71:443-50. [PMID: 22153589 PMCID: PMC3479644 DOI: 10.1016/j.biopsych.2011.11.003] [Citation(s) in RCA: 266] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 10/24/2011] [Accepted: 11/09/2011] [Indexed: 11/16/2022]
Abstract
BACKGROUND Attention-deficit/hyperactivity disorder (ADHD) is typically characterized by symptoms of inattention and hyperactivity/impulsivity, but there is increased recognition of a motivation deficit too. This neuropathology may reflect dysfunction of both attention and reward-motivation networks. METHODS To test this hypothesis, we compared the functional connectivity density between 247 ADHD and 304 typically developing control children from a public magnetic resonance imaging database. We quantified short- and long-range functional connectivity density in the brain using an ultrafast data-driven approach. RESULTS Children with ADHD had lower connectivity (short- and long-range) in regions of the dorsal attention (superior parietal cortex) and default-mode (precuneus) networks and in cerebellum and higher connectivity (short-range) in reward-motivation regions (ventral striatum and orbitofrontal cortex) than control subjects. In ADHD children, the orbitofrontal cortex (region involved in salience attribution) had higher connectivity with reward-motivation regions (striatum and anterior cingulate) and lower connectivity with superior parietal cortex (region involved in attention processing). CONCLUSIONS The enhanced connectivity within reward-motivation regions and their decreased connectivity with regions from the default-mode and dorsal attention networks suggest impaired interactions between control and reward pathways in ADHD that might underlie attention and motivation deficits in ADHD.
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Affiliation(s)
- Dardo Tomasi
- National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland, USA.
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553
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Altered learning and Arc-regulated consolidation of learning in striatum by methamphetamine-induced neurotoxicity. Neuropsychopharmacology 2012; 37:885-95. [PMID: 22071872 PMCID: PMC3280660 DOI: 10.1038/npp.2011.265] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Methamphetamine (METH) causes partial depletion of central monoamine systems and cognitive dysfunction in rats and humans. We have previously shown and now further show that the positive correlation between expression of the immediate-early gene Arc (activity-regulated, cytoskeleton-associated) in the dorsomedial (DM) striatum and learning on a response reversal task is lost in rats with METH-induced striatal dopamine loss, despite normal behavioral performance and unaltered N-methyl-D-aspartate (NMDA) receptor-mediated excitatory post-synaptic currents, suggesting intact excitatory transmission. This discrepancy suggests that METH-pretreated rats may no longer be using the dorsal striatum to solve the reversal task. To test this hypothesis, male Sprague-Dawley rats were pretreated with a neurotoxic regimen of METH or saline. Guide cannulae were surgically implanted bilaterally into the DM striatum. Three weeks after METH treatment, rats were trained on a motor response version of a T-maze task, and then underwent reversal training. Before reversal training, the NMDA receptor antagonist DL-2-amino-5-phosphonopentanoic acid (AP5) or an Arc antisense oligonucleotide was infused into the DM striatum. Acute disruption of DM striatal function by infusion of AP5 impaired reversal learning in saline-, but not METH-, pretreated rats. Likewise, acute disruption of Arc, which is implicated in consolidation of long-term memory, disrupted retention of reversal learning 24 h later in saline-, but not METH-, pretreated rats. These results highlight the critical importance of Arc in the striatum in consolidation of basal ganglia-mediated learning and suggest that long-term toxicity induced by METH alters the cognitive strategies/neural circuits used to solve tasks normally mediated by dorsal striatal function.
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554
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Effect of variation in diacylglycerol kinase η (DGKH) gene on brain function in a cohort at familial risk of bipolar disorder. Neuropsychopharmacology 2012; 37:919-28. [PMID: 22048461 PMCID: PMC3280657 DOI: 10.1038/npp.2011.272] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Several lines of evidence indicate that the diacylglycerol kinase eta (DGKH) gene is implicated in the etiology of bipolar disorder (BD). However, the functional neural mechanisms of DGKH's risk association remain unknown. Therefore, we examined the effects of three haplotype-tagging risk variants in DGKH (single nucleotide polymorphisms rs9315885, rs1012053, and rs1170191) on brain activation using a verbal fluency functional magnetic resonance imaging task. The subject groups consisted of young individuals at high familial risk of BD (n=81) and a comparison group of healthy controls (n=75). Individuals were grouped based on risk haplotypes described in previous studies. There was a significant risk haplotype*group interaction in the left medial frontal gyrus (BA10, involving anterior cingulate BA32), left precuneus, and right parahippocampal gyrus. All regions demonstrated greater activation during the baseline condition than sentence completion. Individuals at high familial risk for BD homozygous for the DGKH risk haplotype demonstrated relatively greater activation (poor suppression) of these regions during the task vs the low-risk haplotype subjects. The reverse pattern was seen for the control subjects. These findings suggest that there are differential effects of the DGKH gene in healthy controls vs the bipolar high-risk group, which manifests as a failure to disengage default-mode regions in those at familial risk carrying the risk haplotype.
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555
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Epperson CN, Amin Z, Ruparel K, Gur R, Loughead J. Interactive effects of estrogen and serotonin on brain activation during working memory and affective processing in menopausal women. Psychoneuroendocrinology 2012; 37:372-82. [PMID: 21820247 PMCID: PMC3226892 DOI: 10.1016/j.psyneuen.2011.07.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/15/2011] [Accepted: 07/05/2011] [Indexed: 01/22/2023]
Abstract
While cognitive changes and mood instability are frequent symptoms reported by menopausal women, the degree to which the decline in estrogen production is responsible is not yet clear. Several lines of evidence suggest that estrogen may produce its effects on cognition and mood through modulation of serotonergic function. To test this hypothesis, we used the tryptophan depletion (TD) paradigm to lower central serotonin levels and pharmacologically manipulated estrogen levels in healthy menopausal women. We examined the individual and combined effects of estradiol and serotonin on working memory, emotion processing and task-related brain activation. Eight healthy predominantly early postmenopausal women underwent TD or sham depletion followed by functional magnetic resonance imaging (fMRI) both before and after short-term transdermal estradiol 75-150 μg/d administration. There was an estradiol treatment by TD interaction for brain activation during performance on both the N-back Task (working memory) and Emotion Identification Task (affective processing). During the 2-back condition, TD attenuated activation prior to, but not after, estradiol treatment in the right and left dorsal lateral prefrontal and middle frontal/cingulate gyrus. During emotion identification, TD heightened activation in the orbital frontal cortex and bilateral amygdala, and this effect was attenuated by estradiol treatment. These results provide preliminary evidence that serotonergic effects directly mediate the impact of estrogen on brain activation during working memory and affective processing.
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556
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Tejeda HA, Shippenberg TS, Henriksson R. The dynorphin/κ-opioid receptor system and its role in psychiatric disorders. Cell Mol Life Sci 2012; 69:857-96. [PMID: 22002579 PMCID: PMC11114766 DOI: 10.1007/s00018-011-0844-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 09/16/2011] [Accepted: 09/19/2011] [Indexed: 10/16/2022]
Abstract
The dynorphin/κ-opioid receptor system has been implicated in the pathogenesis and pathophysiology of several psychiatric disorders. In the present review, we present evidence indicating a key role for this system in modulating neurotransmission in brain circuits that subserve mood, motivation, and cognitive function. We overview the pharmacology, signaling, post-translational, post-transcriptional, transcriptional, epigenetic and cis regulation of the dynorphin/κ-opioid receptor system, and critically review functional neuroanatomical, neurochemical, and pharmacological evidence, suggesting that alterations in this system may contribute to affective disorders, drug addiction, and schizophrenia. We also overview the dynorphin/κ-opioid receptor system in the genetics of psychiatric disorders and discuss implications of the reviewed material for therapeutics development.
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Affiliation(s)
- H. A. Tejeda
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, 20 Penn St., Baltimore, MD 21201 USA
| | - T. S. Shippenberg
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
| | - R. Henriksson
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
- Department of Clinical Neuroscience, Karolinska Institutet, CMM, L8:04, 17176 Stockholm, Sweden
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557
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Scoriels L, Barnett JH, Soma PK, Sahakian BJ, Jones PB. Effects of modafinil on cognitive functions in first episode psychosis. Psychopharmacology (Berl) 2012; 220:249-58. [PMID: 21909634 DOI: 10.1007/s00213-011-2472-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 08/25/2011] [Indexed: 11/24/2022]
Abstract
RATIONALE Cognitive impairments are important determinants of functional outcome in psychosis, which are inadequately treated by antipsychotic medication. Modafinil is a wake-promoting drug that has been shown to improve attention, memory and executive function in the healthy population and in patients with schizophrenia. OBJECTIVES We aimed to establish modafinil's role in the adjunctive treatment of cognitive impairments in the first episode of psychosis, a time when symptoms may be more malleable than at chronic stages of the disease. METHODS Forty patients with a first episode of psychosis participated in a randomised, double-blind, placebo-controlled crossover design study assessing the effects of a single dose of 200 mg modafinil on measures of executive functioning, memory, learning, impulsivity and attention. RESULTS Modafinil improved verbal working memory (d = 0.24, p = 0.04), spatial working memory errors (d = 0.30, p = 0.0004) and strategy use (d = 0.23, p = 0.03). It also reduced discrimination errors in a task testing impulsivity. Modafinil showed no effect on impulsivity measures, sustained attention, attentional set-shifting, learning or fluency. CONCLUSIONS Modafinil selectively enhances working memory in first episode psychosis patients, which could have downstream effects on patients' social and occupational functioning.
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Affiliation(s)
- Linda Scoriels
- Department of Psychiatry, University of Cambridge, Herchel Smith Building for Brain and Mind Sciences, Cambridge Biomedical Campus, Cambridge, CB2 0SZ, UK.
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558
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Bowirrat A, Chen TJH, Oscar-Berman M, Madigan M, Chen AL, Bailey JA, Braverman ER, Kerner M, Giordano J, Morse S, Downs BW, Waite RL, Fornari F, Armaly Z, Blum K. Neuropsychopharmacology and neurogenetic aspects of executive functioning: should reward gene polymorphisms constitute a diagnostic tool to identify individuals at risk for impaired judgment? Mol Neurobiol 2012; 45:298-313. [PMID: 22371275 DOI: 10.1007/s12035-012-8247-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/08/2012] [Indexed: 12/25/2022]
Abstract
Executive functions are processes that act in harmony to control behaviors necessary for maintaining focus and achieving outcomes. Executive dysfunction in neuropsychiatric disorders is attributed to structural or functional pathology of brain networks involving prefrontal cortex (PFC) and its connections with other brain regions. The PFC receives innervations from different neurons associated with a number of neurotransmitters, especially dopamine (DA). Here we review findings on the contribution of PFC DA to higher-order cognitive and emotional behaviors. We suggest that examination of multifactorial interactions of an individual's genetic history, along with environmental risk factors, can assist in the characterization of executive functioning for that individual. Based upon the results of genetic studies, we also propose genetic mapping as a probable diagnostic tool serving as a therapeutic adjunct for augmenting executive functioning capabilities. We conclude that preservation of the neurological underpinnings of executive functions requires the integrity of complex neural systems including the influence of specific genes and associated polymorphisms to provide adequate neurotransmission.
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Affiliation(s)
- Abdalla Bowirrat
- Clinical Neuroscience and Population Genetics, The Nazareth English Hospital (EMME), 16100 Nazareth, Israel.
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559
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Blair C, Raver CC. Individual development and evolution: experiential canalization of self-regulation. Dev Psychol 2012; 48:647-57. [PMID: 22329384 DOI: 10.1037/a0026472] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this article, we contrast evolutionary and psychobiological models of individual development to address the idea that individual development occurring in prototypically risky and unsupportive environments can be understood as adaptation. We question traditional evolutionary explanations of individual development, calling on the principle of probabilistic epigenesis to suggest that individual development resulting from the combined activity of genes and environments is best understood to precede rather than follow from evolutionary change. Specifically, we focus on the ways in which experience shapes the development of stress response physiology, with implications for individual development and intergenerational transmission of reactive, as opposed to reflective, phenotypes. In doing so, we describe results from several analyses conducted with a longitudinal data set of 1,292 children and their primary caregivers followed from birth. Our results indicate that the effects of poverty on stress response physiology and on the development of the self-regulation of behavior represent instances of the experiential canalization of development with implications for understanding the genesis and "adaptiveness" of risk behavior.
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Affiliation(s)
- Clancy Blair
- Department of Applied Psychology, New York University, New York, NY 10003, USA.
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560
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Melis M, Muntoni AL, Pistis M. Endocannabinoids and the processing of value-related signals. Front Pharmacol 2012; 3:7. [PMID: 22347186 PMCID: PMC3270484 DOI: 10.3389/fphar.2012.00007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/12/2012] [Indexed: 12/23/2022] Open
Abstract
Endocannabinoids serve as retrograde signaling molecules at many synapses within the CNS, particularly GABAergic and glutamatergic synapses. Synapses onto midbrain dopamine (DA) neurons in the ventral tegmental area (VTA) make no exception to this rule. In fact, the effects of cannabinoids on dopamine transmission as well as DA-related behaviors are generally exerted through the modulation of inhibitory and excitatory afferents impinging onto DA neurons. Endocannabinoids, by regulating different forms of synaptic plasticity in the VTA, provide a critical modulation of the DA neuron output and, ultimately, of the systems driving and regulating motivated behaviors. Because DA cells exhibit diverse states of activity, which crucially depend on their intrinsic properties and afferent drive, the understanding of the role played by endocannabinoids in synaptic modulations is critical for their overall functions. Particularly, endocannabinoids by selectively inhibiting afferent activity may alter the functional states of DA neurons and potentiate the responsiveness of the reward system to phasic DA.
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Affiliation(s)
- Miriam Melis
- B.B. Brodie Department of Neuroscience, University of Cagliari Monserrato, Italy
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561
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Millan MJ, Agid Y, Brüne M, Bullmore ET, Carter CS, Clayton NS, Connor R, Davis S, Deakin B, DeRubeis RJ, Dubois B, Geyer MA, Goodwin GM, Gorwood P, Jay TM, Joëls M, Mansuy IM, Meyer-Lindenberg A, Murphy D, Rolls E, Saletu B, Spedding M, Sweeney J, Whittington M, Young LJ. Cognitive dysfunction in psychiatric disorders: characteristics, causes and the quest for improved therapy. Nat Rev Drug Discov 2012; 11:141-68. [PMID: 22293568 DOI: 10.1038/nrd3628] [Citation(s) in RCA: 786] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Studies of psychiatric disorders have traditionally focused on emotional symptoms such as depression, anxiety and hallucinations. However, poorly controlled cognitive deficits are equally prominent and severely compromise quality of life, including social and professional integration. Consequently, intensive efforts are being made to characterize the cellular and cerebral circuits underpinning cognitive function, define the nature and causes of cognitive impairment in psychiatric disorders and identify more effective treatments. Successful development will depend on rigorous validation in animal models as well as in patients, including measures of real-world cognitive functioning. This article critically discusses these issues, highlighting the challenges and opportunities for improving cognition in individuals suffering from psychiatric disorders.
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Affiliation(s)
- Mark J Millan
- Institut de Recherche Servier, 78290 Croissy/Seine, France.
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562
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Grant JE, Chamberlain SR, Schreiber L, Odlaug BL. Neuropsychological deficits associated with cannabis use in young adults. Drug Alcohol Depend 2012; 121:159-62. [PMID: 21920674 PMCID: PMC3242860 DOI: 10.1016/j.drugalcdep.2011.08.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 08/16/2011] [Accepted: 08/18/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND Cannabis is the most widely used illicit substance and has been associated with cognitive impairment. It is unclear whether such impairment can occur in the absence of potential confounding influences of co-morbid axis-I disorders and use of other illicit substances. METHOD Young adult volunteers (18-29 years) were recruited from the general community on the basis of having no axis-I disorders or history of illicit substance use other than cannabis use. Subjects were then grouped according to presence or absence of cannabis use (>1 time/week over past 12 months). Cognition was compared between groups using selected paradigms from the CANTAB. RESULTS Cannabis users (N=16) and controls (N=214) did not differ significantly on salient demographic characteristics. Compared to controls, cannabis users showed significant impairments on quality of decision-making (Cambridge Gamble task), and executive planning (One Touch Stockings of Cambridge task). Response inhibition, spatial working memory, and sustained attention were intact. CONCLUSIONS This study identified cognitive deficits in cannabis users even in the absence of axis-I disorders and a history of using other illicit drugs. Future work should use longitudinal designs to track whether these deficits predate cannabis use or are due to its consumption.
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Affiliation(s)
- Jon E Grant
- Department of Psychiatry, University of Minnesota School of Medicine, 2450 Riverside Avenue, Minneapolis, MN 55454, United States.
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563
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Shehzad Z, DeYoung CG, Kang Y, Grigorenko EL, Gray JR. Interaction of COMT val158met and externalizing behavior: relation to prefrontal brain activity and behavioral performance. Neuroimage 2012; 60:2158-68. [PMID: 22306803 DOI: 10.1016/j.neuroimage.2012.01.097] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 01/16/2012] [Accepted: 01/18/2012] [Indexed: 01/16/2023] Open
Abstract
A promising approach in neuroimaging studies aimed at understanding effects of single genetic variants on behavior is the study of gene-trait interactions. Variation in the catechol-O-methyl-transferase gene (COMT) is associated with the regulation of dopamine levels in the prefrontal cortex and with cognitive functioning. Given the involvement of dopaminergic neurotransmission in externalizing behavior, a trait characterized by impulsivity and aggression, especially in men, externalizing (as a trait) may index a set of genetic, environmental, and neural characteristics pertinent to understanding phenotypic effects of genetic variation in the COMT gene. In the current study, we used a gene-trait approach to investigate effects of the COMT val(158)met polymorphism and externalizing on brain activity during moments involving low or high demands on cognitive control. In 104 male participants, interference-related activation depended conjointly on externalizing and val(158)met: stronger activation in the dorsal anterior cingulate and lateral prefrontal cortex was found for val/val individuals with high trait externalizing while stronger activation in cingulate motor areas and sensorimotor precuneus was found for met/met individuals with low externalizing. Our results suggest that the val/val genotype, coupled with high levels of trait externalizing, lowers the efficiency of stimulus conflict resolution, whereas the met/met genotype, coupled with low levels of externalizing, lowers the efficiency of response selection.
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Affiliation(s)
- Zarrar Shehzad
- Department of Psychology, Yale University, New Haven, CT, USA
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564
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Smith ME, Farah MJ. Are prescription stimulants "smart pills"? The epidemiology and cognitive neuroscience of prescription stimulant use by normal healthy individuals. Psychol Bull 2012; 137:717-41. [PMID: 21859174 DOI: 10.1037/a0023825] [Citation(s) in RCA: 283] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Use of prescription stimulants by normal healthy individuals to enhance cognition is said to be on the rise. Who is using these medications for cognitive enhancement, and how prevalent is this practice? Do prescription stimulants in fact enhance cognition for normal healthy people? We review the epidemiological and cognitive neuroscience literatures in search of answers to these questions. Epidemiological issues addressed include the prevalence of nonmedical stimulant use, user demographics, methods by which users obtain prescription stimulants, and motivations for use. Cognitive neuroscience issues addressed include the effects of prescription stimulants on learning and executive function, as well as the task and individual variables associated with these effects. Little is known about the prevalence of prescription stimulant use for cognitive enhancement outside of student populations. Among college students, estimates of use vary widely but, taken together, suggest that the practice is commonplace. The cognitive effects of stimulants on normal healthy people cannot yet be characterized definitively, despite the volume of research that has been carried out on these issues. Published evidence suggests that declarative memory can be improved by stimulants, with some evidence consistent with enhanced consolidation of memories. Effects on the executive functions of working memory and cognitive control are less reliable but have been found for at least some individuals on some tasks. In closing, we enumerate the many outstanding questions that remain to be addressed by future research and also identify obstacles facing this research.
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Affiliation(s)
- M Elizabeth Smith
- Department of Psychology, University of Pennsylvania, 3720 Walnut Street, Philadelphia, PA 19104, USA
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565
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Thalamic contributions to Basal Ganglia-related behavioral switching and reinforcement. J Neurosci 2012; 31:16102-6. [PMID: 22072662 DOI: 10.1523/jneurosci.4634-11.2011] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although the existence of prominent connections between the intralaminar thalamic nuclei and the basal ganglia has long been established, the limited knowledge of the functional relevance of this network has considerably hampered progress in our understanding of the neural mechanisms by which the thalamostriatal system integrates and regulates the basal ganglia circuitry. In this brief commentary, we will address this gap of knowledge through a discussion of the key points of a symposium entitled "Thalamic Contributions to Basal Ganglia-Related Behavioral Switching and Reinforcement" that will be presented at the 2011 Society for Neuroscience meeting. Recent anatomical and physiological data that support the role of the thalamostriatal system in action selection, attentional shifting, and reinforcement will be discussed. We will also address the possibility that degeneration of the thalamostriatal system could underlie some of the deficits in redirection of attention in response to salient stimuli seen in Parkinson's disease.
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566
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Effects of α-2A adrenergic receptor agonist on time and risk preference in primates. Psychopharmacology (Berl) 2012; 219:363-75. [PMID: 21979441 PMCID: PMC3269972 DOI: 10.1007/s00213-011-2520-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 09/20/2011] [Indexed: 11/27/2022]
Abstract
RATIONALE Subjective values of actions are influenced by the uncertainty and immediacy of expected rewards. Multiple brain areas, including the prefrontal cortex and basal ganglia, are implicated in selecting actions according to their subjective values. Alterations in these neural circuits, therefore, might contribute to symptoms of impulsive choice behaviors in disorders such as substance abuse and attention-deficit hyperactivity disorder (ADHD). In particular, the α-2A noradrenergic system is known to have a key influence on prefrontal cortical circuits, and medications that stimulate this receptor are currently in use for the treatment of ADHD. OBJECTIVE We tested whether the preference of rhesus monkeys for delayed and uncertain reward is influenced by the α-2A adrenergic receptor agonist, guanfacine. METHODS In each trial, the animal chose between a small, certain and immediate reward and another larger, more delayed reward. In half of the trials, the larger reward was certain, whereas in the remaining trials, the larger reward was uncertain. RESULTS Guanfacine increased the tendency for the animal to choose the larger and more delayed reward only when it was certain. By applying an econometric model to the animal's choice behavior, we found that guanfacine selectively reduced the animal's time preference, increasing their choice of delayed, larger rewards, without significantly affecting their risk preference. CONCLUSIONS In combination with previous findings that guanfacine improves the efficiency of working memory and other prefrontal functions, these results suggest that impulsive choice behaviors may also be ameliorated by strengthening prefrontal functions.
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567
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Homberg JR. Serotonin and decision making processes. Neurosci Biobehav Rev 2012; 36:218-36. [DOI: 10.1016/j.neubiorev.2011.06.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Revised: 05/27/2011] [Accepted: 06/02/2011] [Indexed: 10/18/2022]
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568
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Kuzmin A, Liljequist S, Meis J, Chefer V, Shippenberg T, Bakalkin G. Repeated moderate-dose ethanol bouts impair cognitive function in Wistar rats. Addict Biol 2012; 17:132-40. [PMID: 22026443 PMCID: PMC3711111 DOI: 10.1111/j.1369-1600.2010.00224.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effects of repeated, intermittent administration of a moderate dose of ethanol (3.4 g/kg/day × 6 days, intragastrically via gavages) on cognitive function were examined in male Wistar rats. No significant differences in weight gain between the ethanol- and water-treated rats were found. Analysis of physical dependence revealed no signs of spontaneous withdrawal, whereas withdrawal signs exacerbated by Ro15-4513, an inverse benzodiazepine agonist, were apparent 5 hours but not 24 hours after the cessation of ethanol treatment. Spatial learning and memory, as assessed in the Barnes maze, were impaired 3-6 days following the treatment but recovered by the 11th-14th days. Reversal learning, however, was impaired throughout the 2-week observation period. Thus, bouts of moderate-dose ethanol administration transiently impair spatial learning and memory, and promote cognitive inflexibility. The employed ethanol exposure paradigm may provide a model of human cognitive deficits associated with alcohol binge drinking.
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Affiliation(s)
- Alexander Kuzmin
- Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University, Sweden
- Section of Molecular and Behavioral Neuroscience, Department of Clinical Neuroscience, Karolinska Institutet, Sweden
| | - Sture Liljequist
- Section of Molecular and Behavioral Neuroscience, Department of Clinical Neuroscience, Karolinska Institutet, Sweden
| | - Jennifer Meis
- Integrative Neuroscience Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, US Department of Health and Human Services, USA
| | - Vladimir Chefer
- Integrative Neuroscience Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, US Department of Health and Human Services, USA
| | - Toni Shippenberg
- Integrative Neuroscience Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, US Department of Health and Human Services, USA
| | - Georgy Bakalkin
- Division of Biological Research on Drug Dependence, Department of Pharmaceutical Biosciences, Uppsala University, Sweden
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569
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Robinson ESJ. Blockade of noradrenaline re-uptake sites improves accuracy and impulse control in rats performing a five-choice serial reaction time tasks. Psychopharmacology (Berl) 2012; 219:303-12. [PMID: 21800042 DOI: 10.1007/s00213-011-2420-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 07/16/2011] [Indexed: 12/01/2022]
Abstract
RATIONALE Atomoxetine, reboxetine and methylphenidate all act at the noradrenaline transporter (NAT) and atomoxetine and methylphenidate are licensed for the treatment of ADHD. The five-choice serial reaction time task (5CSRTT) provides a valid model to study attention and impulsivity in rodents. Studies using this task have largely failed to demonstrate improvements in attention with atomoxetine and methylphenidate and reboxetine has not been investigated previously. OBJECTIVES The present study used modifications to the standard rat 5CSRTT and demonstrated that blockade of NAT improves attention and reduces premature responding. METHODS Rats were trained in a fixed inter-trial interval (ITI), 5CSRTT then tested at baseline and under conditions to acutely challenge attention and/or impulse control following vehicle or atomoxetine (0.3 mg/kg, i.p.). RESULTS Atomoxetine (0.3 mg/kg, i.p.) significantly improved impulse control under all conditions (p < 0.05) but had no significant effects on accuracy. To increase the attentional demands of the task, rats were re-baselined in a non-paced, variable ITI task where presentations of the stimuli were unpredictable. In the VITI task, atomoxetine (0.0-0.3 mg/kg, i.p.) induced a dose-dependent improvement in accuracy (p < 0.05) and reduction in premature responses (p < 0.05). Reboxetine (0.0-1.0 mg/kg, i.p.) and methylphenidate (1-10 mg/kg, p.o.) did not significantly improve accuracy in the whole population but median split analysis revealed a significant improvement with both drugs, as well as atomoxetine, in the poor performing animals (p < 0.05). CONCLUSIONS These data suggest that blockade of noradrenaline re-uptake sites is an important target in terms of enhancing both attention and impulse control.
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Affiliation(s)
- Emma S J Robinson
- School of Physiology and Pharmacology, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
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570
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Minzenberg MJ, Carter CS. Developing treatments for impaired cognition in schizophrenia. Trends Cogn Sci 2012; 16:35-42. [DOI: 10.1016/j.tics.2011.11.017] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 11/29/2011] [Accepted: 11/30/2011] [Indexed: 12/19/2022]
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571
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Blood CADPS2ΔExon3 expression is associated with intelligence and memory in healthy adults. Biol Psychol 2012; 89:117-22. [DOI: 10.1016/j.biopsycho.2011.09.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 09/26/2011] [Accepted: 09/26/2011] [Indexed: 11/22/2022]
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572
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Dekeyne A, Brocco M, Loiseau F, Gobert A, Rivet JM, Di Cara B, Cremers TI, Flik G, Fone KCF, Watson DJG, Papp M, Sharp T, Serres F, Cespuglio R, Olivier B, Chan JSW, Lavielle G, Millan MJ. S32212, a Novel Serotonin Type 2C Receptor Inverse Agonist/α2-Adrenoceptor Antagonist and Potential Antidepressant: II. A Behavioral, Neurochemical, and Electrophysiological Characterization. J Pharmacol Exp Ther 2011; 340:765-80. [DOI: 10.1124/jpet.111.187534] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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573
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Grégoire S, Rivalan M, Le Moine C, Dellu-Hagedorn F. The synergy of working memory and inhibitory control: behavioral, pharmacological and neural functional evidences. Neurobiol Learn Mem 2011; 97:202-12. [PMID: 22197651 DOI: 10.1016/j.nlm.2011.12.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 11/28/2011] [Accepted: 12/05/2011] [Indexed: 01/09/2023]
Abstract
Concomitant deficits in working memory and behavioral inhibition in several psychiatric disorders like attention-deficit/hyperactivity disorder, addiction or mania, suggest that common brain mechanisms may underlie their etiologies. Based on the theoretical assumption that a continuum exists between health and mental disorders, we explored the relationship between working memory and inhibition in healthy individuals, through spontaneous inter individual differences in behavior, and tested the hypothesis of a functional link through the fronto-striatal dopaminergic system. Rats were classified into three groups, showing good, intermediate and poor working memory and were compared for their inhibitory abilities. These two functions were simultaneously modulated by a dose-effect of d-amphetamine and in situ hybridization was used to quantify dopaminergic receptor (RD1) mRNAs in prefrontal cortex and striatal areas. A functional relationship between working memory and inhibition abilities was revealed. Both functions were similarly modulated by d-amphetamine according to an inverted-U shaped relationship and depending on initial individual performances. D-amphetamine selectively improved working memory and inhibition of poor and intermediate performers at low doses whereas it impaired both processes in good performers at a higher dose. D1 receptors were less expressed in prelimbic, infralimbic and anterior cingulate cortices of good compared to intermediate and poor performers, whereas no difference was observed between groups in striatal areas. The synergy of working memory and inhibitory abilities, observed in both healthy and psychiatric populations, may originate from endogenous variability in dopaminergic prefrontal cortex activity. Such findings confirm the validity of a dimensional approach, based on the concept of continuity between health and mental disorders for identifying endophenotypes of mental disorders.
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Affiliation(s)
- Stéphanie Grégoire
- CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France; Univ. Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France.
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574
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575
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Marzinzik F, Wotka J, Wahl M, Krugel LK, Kordsachia C, Klostermann F. Modulation of habit formation by levodopa in Parkinson's disease. PLoS One 2011; 6:e27695. [PMID: 22110725 PMCID: PMC3218008 DOI: 10.1371/journal.pone.0027695] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 10/22/2011] [Indexed: 11/19/2022] Open
Abstract
Dopamine promotes the execution of positively reinforced actions, but its role for the formation of behaviour when feedback is unavailable remains open. To study this issue, the performance of treated/untreated patients with Parkinson's disease and controls was analysed in an implicit learning task, hypothesising dopamine-dependent adherence to hidden task rules. Sixteen patients on/off levodopa and fourteen healthy subjects engaged in a Go/NoGo paradigm comprising four equiprobable stimuli. One of the stimuli was defined as target which was first consistently preceded by one of the three non-target stimuli (conditioning), whereas this coupling was dissolved thereafter (deconditioning). Two task versions were presented: in a 'Go version', only the target cue required the execution of a button press, whereas non-target stimuli were not instructive of a response; in a 'NoGo version', only the target cue demanded the inhibition of the button press which was demanded upon any non-target stimulus. Levodopa influenced in which task version errors grew from conditioning to deconditioning: in unmedicated patients just as controls errors only rose in the NoGo version with an increase of incorrect responses to target cues. Contrarily, in medicated patients errors went up only in the Go version with an increase of response omissions to target cues. The error increases during deconditioning can be understood as a perpetuation of reaction tendencies acquired during conditioning. The levodopa-mediated modulation of this carry-over effect suggests that dopamine supports habit conditioning under the task demand of response execution, but dampens it when inhibition is required. However, other than in reinforcement learning, supporting dopaminergic actions referred to the most frequent, i. e., non-target behaviour. Since this is passive whenever selective actions are executed against an inactive background, dopaminergic treatment could in according scenarios contribute to passive behaviour in patients with Parkinson's disease.
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Affiliation(s)
- Frank Marzinzik
- Department of Neurology, Campus Benjamin Franklin, Charité-University Medicine Berlin, Berlin, Germany
| | - Johann Wotka
- Department of Neurology, Campus Benjamin Franklin, Charité-University Medicine Berlin, Berlin, Germany
| | - Michael Wahl
- Department of Neurology, Campus Benjamin Franklin, Charité-University Medicine Berlin, Berlin, Germany
| | - Lea K. Krugel
- Department of Neurology, Campus Benjamin Franklin, Charité-University Medicine Berlin, Berlin, Germany
| | | | - Fabian Klostermann
- Department of Neurology, Campus Benjamin Franklin, Charité-University Medicine Berlin, Berlin, Germany
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576
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The role of neuromodulators in selective attention. Trends Cogn Sci 2011; 15:585-91. [PMID: 22074811 DOI: 10.1016/j.tics.2011.10.006] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/24/2011] [Accepted: 10/25/2011] [Indexed: 11/22/2022]
Abstract
Several classes of neurotransmitters exert modulatory effects on a broad and diverse population of neurons throughout the brain. Some of these neuromodulators, especially acetylcholine and dopamine, have long been implicated in the neural control of selective attention. We review recent evidence and evolving ideas about the importance of these neuromodulatory systems in attention, particularly visual selective attention. We conclude that, although our understanding of their role in the neural circuitry of selective attention remains rudimentary, recent research has begun to suggest unique contributions of neuromodulators to different forms of attention, such as bottom-up and top-down attention.
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577
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Croxson PL, Kyriazis DA, Baxter MG. Cholinergic modulation of a specific memory function of prefrontal cortex. Nat Neurosci 2011; 14:1510-2. [PMID: 22057191 PMCID: PMC3432567 DOI: 10.1038/nn.2971] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 09/20/2011] [Indexed: 02/07/2023]
Abstract
Deficits in prefrontal cholinergic function are implicated in cognitive impairment in many neuropsychiatric diseases, but acetylcholine's specific role remains elusive. Rhesus monkeys with selective lesions of cholinergic input to prefrontal cortex (PFC) were unimpaired in tests of decision making and episodic memory that require intact PFC, but were severely impaired on a spatial working memory task. These observations are consistent with a specific role for prefrontal acetylcholine in working memory.
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Affiliation(s)
- Paula L Croxson
- Glickenhaus Laboratory of Neuropsychology and Friedman Brain Institute, Department of Neuroscience, Mount Sinai School of Medicine, New York, New York, USA
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578
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Han X, Li N, Meng Q, Shao F, Wang W. Maternal immune activation impairs reversal learning and increases serum tumor necrosis factor-α in offspring. Neuropsychobiology 2011; 64:9-14. [PMID: 21577008 DOI: 10.1159/000322455] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 10/20/2010] [Indexed: 11/19/2022]
Abstract
Maternal immune activation (MIA) produces a variety of behavioral and brain abnormalities in rodent models of several neuropsychiatric disorders. However, it remains controversial whether MIA impairs reversal learning, a basic function of flexibility relevant to those diseases, in offspring. In the present study, we used the Morris water maze to investigate the effects of middle to late gestation stage poly(I:C) challenges on spatial learning and subsequent reversal learning performance in adolescent rats. Maternal poly(I:C) treatment induced deficits in reversal learning without affecting spatial acquisition abilities. In addition, the serum level of the proinflammatory cytokine tumor necrosis factor-α was increased in MIA rats. This study advances our understanding of how MIA affects adolescent behavior and brain function.
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Affiliation(s)
- Xiao Han
- Department of Psychology, Peking University, Beijing, China
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579
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Fulda S, Szesny N, Ising M, Heck A, Grübl A, Lieb R, Reppermund S. Further evidence for executive dysfunction in subjects with RLS from a non-clinical sample. Sleep Med 2011; 12:1003-7. [PMID: 22000419 DOI: 10.1016/j.sleep.2011.04.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 04/06/2011] [Accepted: 04/10/2011] [Indexed: 11/26/2022]
Abstract
OBJECTIVE AND BACKGROUND Previous studies exploring cognitive functioning in RLS have either relied on medication free subjects sampled within a clinical context or on subjects with RLS symptoms identified within population samples. However, in contrast to clinical samples, population studies so far have not excluded the use of antidepressants, hypnotics, or RLS relevant medication, and study subjects were exclusively older in age. We therefore report on cognitive functioning in predominantly middle-aged individuals with RLS symptoms sampled from the general population and free of mental disorders and of hypnotic, psychopharmacological, or RLS relevant medication. METHODS Participants with RLS symptoms and individually matched controls were identified within the MARS control study, a non-clinical control group study of 550 participants between 18 and 75 years. Cognitive functioning was assessed with the Trail Making Test A and B and a computerized German version of the Wisconsin Card Sorting Test (WCST). Performance was compared between 41 participants with RLS and 133 controls, and between a subgroup of 10 participants with frequent RLS symptoms (≥ 2/week) and 36 matched controls. RESULTS There was no difference in cognitive functioning for the complete group of participants with RLS and controls. However, participants with frequent RLS symptoms showed impaired performance in the WCST. CONCLUSION The results of this study add to the evidence that executive functioning is impaired in individuals with frequent RLS.
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580
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de Visser L, Homberg JR, Mitsogiannis M, Zeeb FD, Rivalan M, Fitoussi A, Galhardo V, van den Bos R, Winstanley CA, Dellu-Hagedorn F. Rodent versions of the iowa gambling task: opportunities and challenges for the understanding of decision-making. Front Neurosci 2011; 5:109. [PMID: 22013406 PMCID: PMC3189637 DOI: 10.3389/fnins.2011.00109] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/29/2011] [Indexed: 01/21/2023] Open
Abstract
Impaired decision-making is a core problem in several psychiatric disorders including attention-deficit/hyperactivity disorder, schizophrenia, obsessive–compulsive disorder, mania, drug addiction, eating disorders, and substance abuse as well as in chronic pain. To ensure progress in the understanding of the neuropathophysiology of these disorders, animal models with good construct and predictive validity are indispensable. Many human studies aimed at measuring decision-making capacities use the Iowa gambling task (IGT), a task designed to model everyday life choices through a conflict between immediate gratification and long-term outcomes. Recently, new rodent models based on the same principle have been developed to investigate the neurobiological mechanisms underlying IGT-like decision-making on behavioral, neural, and pharmacological levels. The comparative strengths, as well as the similarities and differences between these paradigms are discussed. The contribution of these models to elucidate the neurobehavioral factors that lead to poor decision-making and to the development of better treatments for psychiatric illness is considered, along with important future directions and potential limitations.
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Affiliation(s)
- Leonie de Visser
- Department of Neuroscience and Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Netherlands
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581
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Siviy SM, Panksepp J. In search of the neurobiological substrates for social playfulness in mammalian brains. Neurosci Biobehav Rev 2011; 35:1821-30. [DOI: 10.1016/j.neubiorev.2011.03.006] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 03/06/2011] [Accepted: 03/07/2011] [Indexed: 01/04/2023]
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582
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Casten KS, Gray AC, Burwell RD. Discrimination learning and attentional set formation in a mouse model of Fragile X. Behav Neurosci 2011; 125:473-9. [PMID: 21517146 DOI: 10.1037/a0023561] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fragile X Syndrome is the most prevalent genetic cause of mental retardation. Selective deficits in executive function, including inhibitory control and attention, are core features of the disorder. In humans, Fragile X results from a trinucleotide repeat in the Fmr1 gene that renders it functionally silent and has been modeled in mice by targeted deletion of the Fmr1 gene. Fmr1 knockout (KO) mice recapitulate many features of Fragile X syndrome, but evidence for deficits in executive function is inconsistent. To address this issue, we trained wild-type and Fmr1 KO mice on an experimental paradigm that assesses attentional set-shifting. Mice learned to discriminate between stimuli differing in two of three perceptual dimensions. Successful discrimination required attending only to the relevant dimension, while ignoring irrelevant dimensions. Mice were trained on three discriminations in the same perceptual dimension, each followed by a reversal. This procedure normally results in the formation of an attentional set to the relevant dimension. Mice were then required to shift attention and discriminate based on a previously irrelevant perceptual dimension. Wild-type mice exhibited the increase in trials to criterion expected when shifting attention from one perceptual dimension to another. In contrast, the Fmr1 KO group failed to show the expected increase, suggesting impairment in forming an attentional set. Fmr1 KO mice also exhibited a general impairment in learning discriminations and reversals. This is the first demonstration that Fmr1 KO mice show a deficit in attentional set formation.
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583
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Gamo NJ, Arnsten AFT. Molecular modulation of prefrontal cortex: rational development of treatments for psychiatric disorders. Behav Neurosci 2011; 125:282-96. [PMID: 21480691 DOI: 10.1037/a0023165] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dysfunction of the prefrontal cortex (PFC) is a central feature of many psychiatric disorders, such as attention deficit hyperactivity disorder (ADHD), posttraumatic stress disorder (PTSD), schizophrenia, and bipolar disorder. Thus, understanding molecular influences on PFC function through basic research in animals is essential to rational drug development. In this review, we discuss the molecular signaling events initiated by norepinephrine and dopamine that strengthen working memory function mediated by the dorsolateral PFC under optimal conditions, and weaken working memory function during uncontrollable stress. We also discuss how these intracellular mechanisms can be compromised in psychiatric disorders, and how novel treatments based on these findings may restore a molecular environment conducive to PFC regulation of behavior, thought and emotion. Examples of successful translation from animals to humans include guanfacine for the treatment of ADHD and related PFC disorders, and prazosin for the treatment of PTSD.
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Affiliation(s)
- Nao J Gamo
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06520-8001, USA.
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584
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Llado-Pelfort L, Santana N, Ghisi V, Artigas F, Celada P. 5-HT1A Receptor Agonists Enhance Pyramidal Cell Firing in Prefrontal Cortex Through a Preferential Action on GABA Interneurons. Cereb Cortex 2011; 22:1487-97. [DOI: 10.1093/cercor/bhr220] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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585
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Impaired context reversal learning, but not cue reversal learning, in patients with amnestic mild cognitive impairment. Neuropsychologia 2011; 49:3320-6. [PMID: 21856321 DOI: 10.1016/j.neuropsychologia.2011.08.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 08/03/2011] [Accepted: 08/07/2011] [Indexed: 11/21/2022]
Abstract
It has been proposed that reversal learning is impaired following damage to the orbitofrontal and ventromedial frontal cortex (OFC/VMFC) and to the medial temporal lobe (MTL), including the hippocampal formation. However, the exact characteristics of the MTL-associated reversal learning deficit are not known. To investigate this issue, we assessed 30 newly diagnosed patients with amnestic mild cognitive impairment (aMCI) and 30 matched healthy controls. All patients fulfilled the aMCI criteria of the Mayo Clinic Alzheimer's Disease Research Center and underwent head magnetic resonance imaging that confirmed MTL atrophy. Reversal learning was assessed using a novel reinforcement learning task. Participants first acquired and then reversed stimulus-outcome associations based on negative and positive feedback (losing and gaining points). Stimuli consisted of a cue (geometric shapes) and a spatial context (background color or pattern). Neuropsychological assessment included tasks related to the MTL (paired associates learning), dorsolateral prefrontal cortex (DLPFC) (extradimensional shift, One-touch Stockings of Cambridge), and OFC/VMFC (Holiday Apartment Task). Results revealed that, relative to controls, patients with aMCI exhibited a marked reversal learning deficit, which was highly selective for the reversal of context. The acquisition of stimulus-outcome associations and cue reversal learning were spared. Performance on the context reversal learning task significantly correlated with the right hippocampal volume. In addition, patients with aMCI had deficits on tests related to DLPFC but not to OFC/VMFC. However, DLPFC dysfunctions were not associated with context reversal learning. These results suggest that MTL deficits in aMCI selectively affect context reversal learning when OFC/VMFC functions are spared. This deficit is not influenced by the valence of the outcome (positive or negative feedback) and by executive dysfunctions.
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586
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Towards a glutamate hypothesis of depression: an emerging frontier of neuropsychopharmacology for mood disorders. Neuropharmacology 2011; 62:63-77. [PMID: 21827775 DOI: 10.1016/j.neuropharm.2011.07.036] [Citation(s) in RCA: 718] [Impact Index Per Article: 55.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 07/22/2011] [Accepted: 07/23/2011] [Indexed: 12/12/2022]
Abstract
Half a century after the first formulation of the monoamine hypothesis, compelling evidence implies that long-term changes in an array of brain areas and circuits mediating complex cognitive-emotional behaviors represent the biological underpinnings of mood/anxiety disorders. A large number of clinical studies suggest that pathophysiology is associated with dysfunction of the predominant glutamatergic system, malfunction in the mechanisms regulating clearance and metabolism of glutamate, and cytoarchitectural/morphological maladaptive changes in a number of brain areas mediating cognitive-emotional behaviors. Concurrently, a wealth of data from animal models have shown that different types of environmental stress enhance glutamate release/transmission in limbic/cortical areas and exert powerful structural effects, inducing dendritic remodeling, reduction of synapses and possibly volumetric reductions resembling those observed in depressed patients. Because a vast majority of neurons and synapses in these areas and circuits use glutamate as neurotransmitter, it would be limiting to maintain that glutamate is in some way 'involved' in mood/anxiety disorders; rather it should be recognized that the glutamatergic system is a primary mediator of psychiatric pathology and, potentially, also a final common pathway for the therapeutic action of antidepressant agents. A paradigm shift from a monoamine hypothesis of depression to a neuroplasticity hypothesis focused on glutamate may represent a substantial advancement in the working hypothesis that drives research for new drugs and therapies. Importantly, despite the availability of multiple classes of drugs with monoamine-based mechanisms of action, there remains a large percentage of patients who fail to achieve a sustained remission of depressive symptoms. The unmet need for improved pharmacotherapies for treatment-resistant depression means there is a large space for the development of new compounds with novel mechanisms of action such as glutamate transmission and related pathways. This article is part of a Special Issue entitled 'Anxiety and Depression'.
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587
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Barak S, Weiner I. Putative cognitive enhancers in preclinical models related to schizophrenia: The search for an elusive target. Pharmacol Biochem Behav 2011; 99:164-89. [DOI: 10.1016/j.pbb.2011.03.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/27/2011] [Accepted: 03/12/2011] [Indexed: 12/12/2022]
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588
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Zhou X, Qi XL, Douglas K, Palaninathan K, Kang HS, Buccafusco JJ, Blake DT, Constantinidis C. Cholinergic modulation of working memory activity in primate prefrontal cortex. J Neurophysiol 2011; 106:2180-8. [PMID: 21795623 DOI: 10.1152/jn.00148.2011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The prefrontal cortex, a cortical area essential for working memory and higher cognitive functions, is modulated by a number of neurotransmitter systems, including acetylcholine; however, the impact of cholinergic transmission on prefrontal activity is not well understood. We relied on systemic administration of a muscarinic receptor antagonist, scopolamine, to investigate the role of acetylcholine on primate prefrontal neuronal activity during execution of working memory tasks and recorded neuronal activity with chronic electrode arrays and single electrodes. Our results indicated a dose-dependent decrease in behavioral performance after scopolamine administration in all the working memory tasks we tested. The effect could not be accounted for by deficits in visual processing, eye movement responses, or attention, because the animals performed a visually guided saccade task virtually error free, and errors to distracting stimuli were not increased. Performance degradation under scopolamine was accompanied by decreased firing rate of the same cortical sites during the delay period of the task and decreased selectivity for the spatial location of the stimuli. These results demonstrate that muscarinic blockade impairs performance in working memory tasks and prefrontal activity mediating working memory.
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Affiliation(s)
- Xin Zhou
- Dept. of Neurobiology and Anatomy, Wake Forest Univ. School of Medicine, Medical Center Blvd., Winston Salem, NC 27157, USA
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589
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Neuronal basis of age-related working memory decline. Nature 2011; 476:210-3. [PMID: 21796118 DOI: 10.1038/nature10243] [Citation(s) in RCA: 305] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/23/2011] [Indexed: 01/16/2023]
Abstract
Many of the cognitive deficits of normal ageing (forgetfulness, distractibility, inflexibility and impaired executive functions) involve prefrontal cortex (PFC) dysfunction. The PFC guides behaviour and thought using working memory, which are essential functions in the information age. Many PFC neurons hold information in working memory through excitatory networks that can maintain persistent neuronal firing in the absence of external stimulation. This fragile process is highly dependent on the neurochemical environment. For example, elevated cyclic-AMP signalling reduces persistent firing by opening HCN and KCNQ potassium channels. It is not known if molecular changes associated with normal ageing alter the physiological properties of PFC neurons during working memory, as there have been no in vivo recordings, to our knowledge, from PFC neurons of aged monkeys. Here we characterize the first recordings of this kind, revealing a marked loss of PFC persistent firing with advancing age that can be rescued by restoring an optimal neurochemical environment. Recordings showed an age-related decline in the firing rate of DELAY neurons, whereas the firing of CUE neurons remained unchanged with age. The memory-related firing of aged DELAY neurons was partially restored to more youthful levels by inhibiting cAMP signalling, or by blocking HCN or KCNQ channels. These findings reveal the cellular basis of age-related cognitive decline in dorsolateral PFC, and demonstrate that physiological integrity can be rescued by addressing the molecular needs of PFC circuits.
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590
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Aarts E, van Holstein M, Cools R. Striatal Dopamine and the Interface between Motivation and Cognition. Front Psychol 2011; 2:163. [PMID: 21808629 PMCID: PMC3139101 DOI: 10.3389/fpsyg.2011.00163] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 06/30/2011] [Indexed: 01/15/2023] Open
Abstract
Brain dopamine has long been known to be implicated in the domains of appetitive motivation and cognition. Recent work indicates that dopamine also plays a role in the interaction between appetitive motivation and cognition. Here we review this work. Animal work has revealed an arrangement of spiraling connections between the midbrain and the striatum that subserves a mechanism by which dopamine can direct information flow from ventromedial to more dorsal regions in the striatum. In line with current knowledge about dopamine's effects on cognition, we hypothesize that these striato-nigro-striatal connections provide the basis for functionally specific effects of appetitive motivation on cognition. One implication of this hypothesis is that appetitive motivation can induce cognitive improvement or impairment depending on task demands.
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Affiliation(s)
- Esther Aarts
- Helen Wills Neuroscience Institute, University of California Berkeley, CA, USA
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591
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Jepma M, Deinum J, Asplund CL, Rombouts SARB, Tamsma JT, Tjeerdema N, Spapé MM, Garland EM, Robertson D, Lenders JWM, Nieuwenhuis S. Neurocognitive function in dopamine-β-hydroxylase deficiency. Neuropsychopharmacology 2011; 36:1608-19. [PMID: 21471955 PMCID: PMC3138665 DOI: 10.1038/npp.2011.42] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Dopamine-β-hydroxylase (DβH) deficiency is a rare genetic syndrome characterized by the complete absence of norepinephrine in the peripheral and the central nervous system. DβH-deficient patients suffer from several physical symptoms, which can be treated successfully with L-threo-3,4-dihydroxyphenylserine, a synthetic precursor of norepinephrine. Informal clinical observations suggest that DβH-deficient patients do not have obvious cognitive impairments, even when they are not medicated, which is remarkable given the important role of norepinephrine in normal neurocognitive function. This study provided the first systematic investigation of neurocognitive function in human DβH deficiency. We tested 5 DβH-deficient patients and 10 matched healthy control participants on a comprehensive cognitive task battery, and examined their pupil dynamics, brain structure, and the P3 component of the electroencephalogram. All participants were tested twice; the patients were tested once ON and once OFF medication. Magnetic resonance imaging scans of the brain revealed that the patients had a smaller total brain volume than the control group, which is in line with the recent hypothesis that norepinephrine has a neurotrophic effect. In addition, the patients showed an abnormally small or absent task-evoked pupil dilation. However, we found no substantial differences in cognitive performance or P3 amplitude between the patients and the control participants, with the exception of a temporal-attention deficit in the patients OFF medication. The largely spared neurocognitive function in DβH-deficient patients suggests that other neuromodulators have taken over the function of norepinephrine in the brains of these patients.
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Affiliation(s)
- Marieke Jepma
- Leiden University, Institute of Psychology, Leiden, The Netherlands.
| | - Jaap Deinum
- Division of Vascular Medicine, Department of Internal Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Christopher L Asplund
- Department of Psychology, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN, USA
| | - Serge ARB Rombouts
- Leiden University, Institute of Psychology, Leiden, The Netherlands,Leiden Institute for Brain and Cognition (LIBC), Leiden, The Netherlands,Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jouke T Tamsma
- Department of General Internal Medicine & Endocrinology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Nathanja Tjeerdema
- Department of General Internal Medicine & Endocrinology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Michiel M Spapé
- School of Psychology, University of Nottingham, Nottingham, UK
| | - Emily M Garland
- Autonomic Dysfunction Center and Department of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - David Robertson
- Autonomic Dysfunction Center and Department of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jacques WM Lenders
- Division of Vascular Medicine, Department of Internal Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Department of Medicine III, Carl Gustav Carus University Medical Center, Dresden, Germany
| | - Sander Nieuwenhuis
- Leiden University, Institute of Psychology, Leiden, The Netherlands,Leiden Institute for Brain and Cognition (LIBC), Leiden, The Netherlands
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592
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Pharmacological stimulation of locus coeruleus reveals a new antipsychotic-responsive pathway for deficient sensorimotor gating. Neuropsychopharmacology 2011; 36:1656-67. [PMID: 21508929 PMCID: PMC3138657 DOI: 10.1038/npp.2011.47] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Surprisingly little is known about the modulation of core endophenotypes of psychiatric disease by discrete noradrenergic (NE) circuits. Prepulse inhibition (PPI), the diminution of startle responses when weak prestimuli precede the startling event, is a widely validated translational paradigm for information-processing deficits observed in several mental disorders including schizophrenia, Tourette's syndrome, and post-traumatic stress disorder (PTSD). Despite putative NE disturbances in these illnesses, NE regulation of PPI remains poorly understood. In these studies, regulation of PPI by the locus coeruleus (LC), the primary source of NE to forebrain, was evaluated in rats using well-established protocols to pharmacologically activate/inactivate this nucleus. The ability of drugs that treat deficient PPI in these illnesses to reverse LC-mediated PPI deficits was also tested. Stimulation of LC receptors produced an anatomically and behaviorally specific deficit in PPI that was blocked by clonidine (Cataprese, an α2 receptor agonist that reduces LC neuronal firing after peri-LC delivery), a postsynaptic α1 NE receptor antagonist (prazosin), and second-generation antipsychotics (olanzapine, seroquel), but not by drugs that antagonized dopamine-1 (SCH23390), dopamine-2 (the first-generation antipsychotic Haloperidol), or serotonin-2 receptors (ritanserin). These results indicate a novel substrate in the regulation of PPI and reveal a novel functional role for the LC. Hence, a hyperactive LC-NE system might underlie a deficient sensorimotor gating endophenotype in a subset of patients suffering from psychiatric illnesses including schizophrenia, Tourette's syndrome, and PTSD, and the ability to normalize LC-NE transmission could contribute to the clinical efficacy of certain drugs (Cataprese, prazosin, and second-generation antipsychotics) in these conditions.
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593
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Beste C, Domschke K, Radenz B, Falkenstein M, Konrad C. The functional 5-HT1A receptor polymorphism affects response inhibition processes in a context-dependent manner. Neuropsychologia 2011; 49:2664-72. [DOI: 10.1016/j.neuropsychologia.2011.05.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 05/02/2011] [Accepted: 05/19/2011] [Indexed: 11/16/2022]
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594
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Bari A, Mar AC, Theobald DE, Elands SA, Oganya KCNA, Eagle DM, Robbins TW. Prefrontal and monoaminergic contributions to stop-signal task performance in rats. J Neurosci 2011; 31:9254-63. [PMID: 21697375 PMCID: PMC3145112 DOI: 10.1523/jneurosci.1543-11.2011] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 04/13/2011] [Indexed: 11/21/2022] Open
Abstract
Defining the neural and neurochemical substrates of response inhibition is of crucial importance for the study and treatment of pathologies characterized by impulsivity such as attention-deficit/hyperactivity disorder and addiction. The stop-signal task (SST) is one of the most popular paradigms used to study the speed and efficacy of inhibitory processes in humans and other animals. Here we investigated the effect of temporarily inactivating different prefrontal subregions in the rat by means of muscimol microinfusions on SST performance. We found that dorsomedial prefrontal cortical areas are important for inhibiting an already initiated response. We also investigated the possible neural substrates of the selective noradrenaline reuptake inhibitor atomoxetine via its local microinfusion into different subregions of the rat prefrontal cortex. Our results show that both orbitofrontal and dorsal prelimbic cortices mediate the beneficial effects of atomoxetine on SST performance. To assess the neurochemical specificity of these effects, we infused the α2-adrenergic agonist guanfacine and the D(1)/D(2) antagonist α-flupenthixol in dorsal prelimbic cortex to interfere with noradrenergic and dopaminergic neurotransmission, respectively. Guanfacine, which modulates noradrenergic neurotransmission, selectively impaired stopping, whereas blocking dopaminergic receptors by α-flupenthixol infusion prolonged go reaction time only, confirming the important role of noradrenergic neurotransmission in response inhibition. These results show that, similar to humans, distinct networks play important roles during SST performance in the rat and that they are differentially modulated by noradrenergic and dopaminergic neurotransmission. This study advances our understanding of the neuroanatomical and neurochemical determinants of impulsivity, which are relevant for a range of psychiatric disorders.
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Affiliation(s)
- Andrea Bari
- Department of Experimental Psychology and Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, United Kingdom.
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595
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Prins J, Olivier B, Korte SM. Triple reuptake inhibitors for treating subtypes of major depressive disorder: the monoamine hypothesis revisited. Expert Opin Investig Drugs 2011; 20:1107-30. [DOI: 10.1517/13543784.2011.594039] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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596
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Chamberlain SR, Robbins TW, Winder-Rhodes S, Müller U, Sahakian BJ, Blackwell AD, Barnett JH. Translational approaches to frontostriatal dysfunction in attention-deficit/hyperactivity disorder using a computerized neuropsychological battery. Biol Psychiatry 2011; 69:1192-203. [PMID: 21047621 DOI: 10.1016/j.biopsych.2010.08.019] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 08/10/2010] [Accepted: 08/11/2010] [Indexed: 01/28/2023]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a prevalent condition associated with cognitive dysfunction. The Cambridge Neuropsychological Test Automated Battery is a computerized set of tests that has been widely used in ADHD and in translation/back-translation. Following a survey of translational research relevant to ADHD in experimental animals, a comprehensive literature review was conducted of studies that had used core Cambridge Neuropsychological Test Automated Battery tests 1) to evaluate cognitive dysfunction in ADHD and 2) to evaluate effects of salient drugs in patients and in volunteers. Meta-analysis was conducted where four or more independent datasets were available. Meta-analysis revealed medium-large decrements in ADHD for response inhibition (d = .790, p < .001), working memory (d = .883, p < .001), executive planning (d = .491, p < .001), and a small decrement in attentional set shifting (d = .160, p = .040). Qualitative review of the literature showed some consistent patterns. In ADHD, methylphenidate improved working memory, modafinil improved planning, and methylphenidate, modafinil, and atomoxetine improved inhibition. Meta-analysis of modafinil healthy volunteer studies showed no effects on sustained attention or set shifting. Results were paralleled by findings in experimental animals on comparable tests, enabling further analysis of drug mechanisms. Substantial cognitive deficits are present in ADHD, which can be remediated somewhat with current medications and which can readily be modeled in experimental animals using back-translational methodology. The findings suggest overlapping but also distinct early cognitive effects of ADHD medications and have important implications for understanding the pathophysiology of ADHD and for future trials.
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Affiliation(s)
- Samuel R Chamberlain
- Department of Psychiatry and Medical Research Council/Wellcome Trust Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, United Kingdom.
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597
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The roles of dopamine and noradrenaline in the pathophysiology and treatment of attention-deficit/hyperactivity disorder. Biol Psychiatry 2011; 69:e145-57. [PMID: 21550021 DOI: 10.1016/j.biopsych.2011.02.036] [Citation(s) in RCA: 403] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 01/16/2011] [Accepted: 02/15/2011] [Indexed: 12/14/2022]
Abstract
Through neuromodulatory influences over fronto-striato-cerebellar circuits, dopamine and noradrenaline play important roles in high-level executive functions often reported to be impaired in attention-deficit/hyperactivity disorder (ADHD). Medications used in the treatment of ADHD (including methylphenidate, dextroamphetamine and atomoxetine) act to increase brain catecholamine levels. However, the precise prefrontal cortical and subcortical mechanisms by which these agents exert their therapeutic effects remain to be fully specified. Herein, we review and discuss the present state of knowledge regarding the roles of dopamine (DA) and noradrenaline in the regulation of corticostriatal circuits, with a focus on the molecular neuroimaging literature (both in ADHD patients and in healthy subjects). Recent positron emission tomography evidence has highlighted the utility of quantifying DA markers, at baseline or following drug administration, in striatal subregions governed by differential cortical connectivity. This approach opens the possibility of characterizing the neurobiological underpinnings of ADHD (and associated cognitive dysfunction) and its treatment by targeting specific neural circuits. It is anticipated that the application of refined and novel positron emission tomography methodology will help to disentangle the overlapping and dissociable contributions of DA and noradrenaline in the prefrontal cortex, thereby aiding our understanding of ADHD and facilitating new treatments.
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598
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Abstract
Dopamine release in cortical and subcortical structures plays a central role in reward-related neural processes. Within this context, dopaminergic inputs are commonly assumed to play an activating role, facilitating behavioral and cognitive operations necessary to obtain a prospective reward. Here, we provide evidence from human fMRI that this activating role can also be mediated by task-demand-related processes and thus extends beyond situations that only entail extrinsic motivating factors. Using a visual discrimination task in which varying levels of task demands were precued, we found enhanced hemodynamic activity in the substantia nigra (SN) for high task demands in the absence of reward or similar extrinsic motivating factors. This observation thus indicates that the SN can also be activated in an endogenous fashion. In parallel to its role in reward-related processes, reward-independent activation likely serves to recruit the processing resources needed to meet enhanced task demands. Simultaneously, activity in a wide network of cortical and subcortical control regions was enhanced in response to high task demands, whereas areas of the default-mode network were deactivated more strongly. The present observations suggest that the SN represents a core node within a broader neural network that adjusts the amount of available neural and behavioral resources to changing situational opportunities and task requirements, which is often driven by extrinsic factors but can also be controlled endogenously.
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599
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Abstract
The prefrontal cortex (PFC) is thought to modulate sensory signals in posterior cortices during top-down attention1,2, yet little is known about the underlying neural circuitry. Experimental and clinical evidence suggest that prefrontal dopamine plays an important role in cognitive functions3, acting predominantly through D1 receptors (D1Rs). Here we show that dopamine D1Rs mediate prefrontal control of signals within visual cortex. We pharmacologically altered D1R-mediated activity within the frontal eye field (FEF) of the PFC and measured its effects on the responses of neurons within visual cortex. This manipulation was sufficient to enhance the response magnitude, orientation selectivity and response reliability of neurons in area V4 to an extent comparable with the known effects of top-down attention. The observed enhancement in V4 signals was restricted to neurons with response fields (RFs) overlapping the part of visual space affected by the D1R manipulation. Altering D1R or D2R-mediated FEF activity increased saccadic target selection, but the D2R manipulation did not enhance V4 signals. Our results identify a role of D1Rs in mediating the control of visual cortical signals by the PFC and demonstrate how processing within sensory areas can be altered in mental disorders involving prefrontal dopamine.
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600
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Baseline burnout symptoms predict visuospatial executive function during survival school training in special operations military personnel. J Int Neuropsychol Soc 2011; 17:494-501. [PMID: 21466738 DOI: 10.1017/s1355617711000221] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Burnout symptoms, which are characterized by exhaustion, cynicism, and a reduced sense of professional efficacy, may deleteriously affect cognitive function in military personnel. A total of 32 U.S. Military Special Operations personnel enrolled in Survival School completed measures of trauma history, dissociation, and burnout before training. They then completed the Groton Maze Learning Test (GMLT), a neuropsychological measure of integrative visuospatial executive function during three field-based phases of Survival School-enemy evasion, captivity/interrogation, and escape/release from captivity. Lower pre-training perceptions of professional efficacy were associated with reduced executive function during all of the field-based phases of Survival School, even after adjustment for years of education, cynicism, and baseline GMLT scores. Magnitudes of decrements in executive function in Marines with low efficacy relative to those with high efficacy increased as training progressed and ranged from .58 during enemy evasion to .99 during escape/release from captivity. Pre-training perceptions of burnout may predict visuospatial executive function during naturalistic training-related stress in military personnel. Assessment of burnout symptoms, particularly perceptions of professional efficacy, may help identify military personnel at risk for stress-related executive dysfunction.
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