René Hen

Columbia University, New York, New York, United States

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Publications (330)2804.16 Total impact

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    ABSTRACT: Behavioral studies have established a role for adult-born dentate granule cells in discriminating between similar memories. However, it is unclear how these cells mediate memory discrimination. Excitability is enhanced in maturing adult-born neurons, spurring the hypothesis that the activity of these cells "directly" encodes and stores memories. An alternative hypothesis posits that maturing neurons "indirectly" contribute to memory encoding by regulating excitation-inhibition balance. We evaluated these alternatives by using dentate-sensitive active place avoidance tasks to assess experience-dependent changes in dentate field potentials in the presence and absence of neurogenesis. Before training, X-ray ablation of adult neurogenesis-reduced dentate responses to perforant-path stimulation and shifted EPSP-spike coupling leftward. These differences were unchanged after place avoidance training with the shock zone in the initial location, which both groups learned to avoid equally well. In contrast, sham-treated mice decreased dentate responses and shifted EPSP-spike coupling leftward after the shock zone was relocated, whereas X-irradiated mice failed to show these changes in dentate function and were impaired on this test of memory discrimination. During place avoidance, excitation-inhibition coupled neural synchrony in dentate local field potentials was reduced in X-irradiated mice, especially in the θ band. The difference was most prominent during conflict learning, which is impaired in the X-irradiated mice. These findings indicate that maturing adult-born neurons regulate both functional network plasticity in response to memory discrimination and dentate excitation-inhibition coordination. The most parsimonious interpretation of these results is that adult neurogenesis indirectly regulates hippocampal information processing. Adult-born neurons in the hippocampal dentate gyrus are important for flexibly using memories, but the mechanism is controversial. Using tests of hippocampus-dependent place avoidance learning and dentate electrophysiology in mice with normal or ablated neurogenesis, we find that maturing adult-born neurons are crucial only when memory must be used flexibly, and that these neurons regulate dentate gyrus synaptic and spiking responses to neocortical input rather than directly storing information, as has been proposed. A day after learning to avoid the initial or changed locations of shock, the dentate synaptic responses are enhanced or suppressed, respectively, unlike mice lacking adult neurogenesis, which did not change. The contribution of adult neurogenesis to memory is indirect, by regulating dentate excitation-inhibition coupling. Copyright © 2015 the authors 0270-6474/15/3511656-11$15.00/0.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 08/2015; 35(33):11656-66. DOI:10.1523/JNEUROSCI.0885-15.2015 · 6.75 Impact Factor
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    ABSTRACT: Stress exposure is one of the greatest risk factors for psychiatric illnesses like Major Depressive Disorder (MDD) and Post-Traumatic Stress Disorder (PTSD). However, not all individuals exposed to stress develop affective disorders. Stress resilience, the ability to experience stress without developing persistent psychopathology, varies from individual to individual. Enhancing stress resilience in at-risk populations could potentially protect against stress-induced psychiatric disorders. Despite this fact, no resilience-enhancing pharmaceuticals have been identified. Methods: Using a chronic social defeat (SD) stress model, learned helplessness (LH), and a chronic corticosterone (CORT) model in mice, we tested if ketamine (K) could protect against depressive-like behavior. Mice were administered a single dose of saline (Sal) or ketamine and then one week later were subjected to 2 weeks of SD, LH training, or 3 weeks of CORT. Results: SD robustly and reliably induced depressive-like behavior in control (Ctrl) mice. Mice treated with prophylactic ketamine were protected against the deleterious effects of SD in the forced swim test (FST) and in the dominant interaction (DI) test. We confirmed these effects in LH and the CORT model. In the LH model, latency to escape was increased following training—and this effect was prevented by ketamine. In the CORT model, a single dose of ketamine blocked stress-induced behavior in the FST, novelty suppressed feeding (NSF) paradigm, and the sucrose splash test (ST). Conclusions: These data show that ketamine can induce persistent stress resilience and, therefore, may be useful in protecting against stress-induced disorders.
    Biological Psychiatry 05/2015; DOI:10.1016/j.biopsych.2015.04.022 · 10.25 Impact Factor
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    ABSTRACT: Impulsive and aggressive behaviors are both modulated by serotonergic signaling, specifically through the serotonin 1B receptor (5-HT1BR). 5-HT1BR knockout mice show increased aggression and impulsivity, and 5-HT1BR polymorphisms are associated with aggression and drug addiction in humans. To dissect the mechanisms by which the 5-HT1BR affects these phenotypes, we developed a mouse model to spatially and temporally regulate 5-HT1BR expression. Our results demonstrate that forebrain 5-HT1B heteroreceptors expressed during an early postnatal period contribute to the development of the neural systems underlying adult aggression. However, distinct heteroreceptors acting during adulthood are involved in mediating impulsivity. Correlating with the impulsivity, dopamine in the nucleus accumbens is elevated in the absence of 5-HT1BRs and normalized following adult rescue of the receptor. Overall, these data show that while adolescent expression of 5-HT1BRs influences aggressive behavior, a distinct set of 5-HT1B receptors modulates impulsive behavior during adulthood. Copyright © 2015 Elsevier Inc. All rights reserved.
    Neuron 04/2015; 86(3). DOI:10.1016/j.neuron.2015.03.041 · 15.98 Impact Factor
  • Alexis S Hill · Amar Sahay · René Hen
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    ABSTRACT: Adult hippocampal neurogenesis is increased by antidepressants, and is required for some of their behavioral effects. However, it remains unclear whether expanding the population of adult-born neurons is sufficient to affect anxiety and depression-related behavior. Here, we use an inducible transgenic mouse model in which the pro-apoptotic gene Bax is deleted from neural stem cells and their progeny in the adult brain, and thereby increases adult neurogenesis. We find no effects on baseline anxiety and depression-related behavior; however, we find that increasing adult neurogenesis is sufficient to reduce anxiety and depression-related behaviors in mice treated chronically with corticosterone, a mouse model of stress. Thus, neurogenesis differentially affects behavior under baseline conditions and in a model of chronic stress. Moreover, we find no effect of increased adult hippocampal neurogenesis on HPA axis regulation, either at baseline or following chronic corticosterone administration, suggesting that increasing adult hippocampal neurogenesis can affect anxiety and depression-related behavior through a mechanism independent of the HPA axis. The use of future techniques to specifically inhibit BAX in the hippocampus could be used to augment adult neurogenesis, and may therefore represent a novel strategy to promote antidepressant-like behavioral effects.Neuropsychopharmacology accepted article preview online, 02 April 2015. doi:10.1038/npp.2015.85.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 04/2015; DOI:10.1038/npp.2015.85 · 7.83 Impact Factor
  • Bradley R Miller · René Hen
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    ABSTRACT: Newborn neurons are continuously added to the adult hippocampus. Early studies found that adult neurogenesis is impaired in models of depression and anxiety and accelerated by antidepressant treatment. This led to the theory that depression results from impaired adult neurogenesis and restoration of adult neurogenesis leads to recovery. Follow up studies yielded a complex body of often inconsistent results, and the veracity of this theory is uncertain. We propose five criteria for acceptance of this theory, we review the recent evidence for each criterion, and we draw the following conclusions: Diverse animal models of depression and anxiety have impaired neurogenesis. Neurogenesis is consistently boosted by antidepressants in animal models only when animals are stressed. Ablation of neurogenesis in animal models impairs cognitive functions relevant to depression, but only a minority of studies find that ablation causes depression or anxiety. Recent human neuroimaging and postmortem studies are consistent with the neurogenic theory, but they are indirect. Finally, a novel drug developed based on the neurogenic theory is promising in animal models.
    Current Opinion in Neurobiology 02/2015; 30:51–58. DOI:10.1016/j.conb.2014.08.012 · 6.77 Impact Factor
  • Biological Psychiatry 02/2015; 77(3). DOI:10.1016/j.biopsych.2014.11.007 · 10.25 Impact Factor
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    ABSTRACT: Over the past several decades, the proliferation and integration of adult-born neurons into existing hippocampal circuitry has been implicated in a wide range of behaviors, including novelty recognition, pattern separation, spatial learning, anxiety behaviors, and antidepressant response. In this review, we suggest that the diversity in behavioral requirements for new neurons may be partly caused by separate functional roles of individual neurogenic niches. Growing evidence shows that the hippocampal formation can be compartmentalized not only along the classic trisynaptic circuit, but also along a longitudinal septotemporal axis. We suggest that subpopulations of hippocampal adult-born neurons may be specialized for distinct mnemonic- or mood-related behavioral tasks. We will examine the literature supporting a functional and anatomical dissociation of the hippocampus along the longitudinal axis and discuss techniques to functionally dissect the roles of adult-born hippocampal neurons in these distinct subregions. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.
    Cold Spring Harbor perspectives in biology 01/2015; 7(8). DOI:10.1101/cshperspect.a018978 · 8.23 Impact Factor
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    ABSTRACT: Knockout (KO) mice that lack the dopamine transporter (SL6A3; DAT) display increased locomotion that can be attenuated, under some circumstances, by administration of drugs that normally produce psychostimulant-like effects, such as amphetamine and methylphenidate. These results have led to suggestions that DAT KO mice may model features of attention deficit hyperactivity disorder (ADHD) and that these drugs may act upon serotonin (5-HT) systems to produce these unusual locomotor decreasing effects. Evidence from patterns of brain expression and initial pharmacologic studies led us to use genetic and pharmacologic approaches to examine the influence of altered 5-HT1B receptor activity on hyperactivity in DAT KO mice. Heterozygous 5-HT1B KO and pharmacologic 5-HT1B antagonism both attenuated locomotor hyperactivity in DAT KO mice. Furthermore, DAT KO mice with reduced, but not eliminated, 5-HT1B receptor expression regained cocaine-stimulated locomotion, which was absent in DAT KO mice with normal levels of 5-HT1B receptor expression. Further experiments demonstrated that the degree of habituation to the testing apparatus determined whether cocaine had no effect on locomotion in DAT KO or reduced locomotion, helping to resolve differences among prior reports. These findings of complementation of the locomotor effects of DAT KO by reducing 5-HT1B receptor activity underscore roles for interactions between specific 5-HT receptors and dopamine (DA) systems in basal and cocaine-stimulated locomotion and support evaluation of 5-HT1B antagonists as potential, non-stimulant ADHD therapeutics.
    PLoS ONE 12/2014; 9(12):e115009. DOI:10.1371/journal.pone.0115009 · 3.23 Impact Factor
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    ABSTRACT: Selective serotonin reuptake inhibitors are the mostly widely used treatment for major depressive disorders and also are prescribed for several anxiety disorders. However, similar to most antidepressants, selective serotonin reuptake inhibitors suffer from two major problems: They only show beneficial effects after 2 to 4 weeks and only about 33% of patients show remission to first-line treatment. Thus, there is a considerable need for development of more effective antidepressants. There is a growing body of evidence supporting critical roles of 5-HT1A and 5-HT4 receptor subtypes in mediating successful depression treatments. In addition, appropriate activation of these receptors may be associated with a faster onset of the therapeutic response. This review will examine the known roles of 5-HT1A and 5-HT4 receptors in mediating both the pathophysiology of depression and anxiety and the treatment of these mood disorders. At the end of the review, the role of these receptors in the regulation of adult hippocampal neurogenesis will also be discussed. Ultimately, we propose that novel antidepressant drugs that selectively target these serotonin receptors could be developed to yield improvements over current treatments for major depressive disorders. © The Author(s) 2014.
    The Neuroscientist 12/2014; DOI:10.1177/1073858414561303 · 7.62 Impact Factor
  • 53rd Annual Meeting of the American-College-of-Neuropsychopharmacology; 12/2014
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    ABSTRACT: Adult neurogenesis, the generation of new neurons in the adult brain, occurs in the hippocampal dentate gyrus (DG) and the olfactory bulb (OB) of all mammals, but the functions of these new neurons are not entirely clear. Originally, adult-born neurons were considered to have excitatory effects on the DG network, but recent studies suggest a net inhibitory effect. Therefore, we hypothesized that selective removal of newborn neurons would lead to increased susceptibility to the effects of a convulsant. This hypothesis was tested by evaluating the response to the chemoconvulsant kainic acid (KA) in mice with reduced adult neurogenesis, produced either by focal X-irradiation of the DG, or by pharmacogenetic deletion of dividing radial glial precursors. In the first 4 hrs after KA administration, when mice have the most robust seizures, mice with reduced adult neurogenesis had more severe convulsive seizures, exhibited either as a decreased latency to the first convulsive seizure, greater number of convulsive seizures, or longer convulsive seizures. Nonconvulsive seizures did not appear to change or they decreased. Four-21 hrs after KA injection, mice with reduced adult neurogenesis showed more interictal spikes (IIS) and delayed seizures than controls. Effects were greater when the anticonvulsant ethosuximide was injected 30 min prior to KA administration; ethosuximide allows forebrain seizure activity to be more easily examined in mice by suppressing seizures dominated by the brainstem. These data support the hypothesis that reduction of adult-born neurons increases the susceptibility of the brain to effects of KA. Copyright © 2014. Published by Elsevier Inc.
    Experimental Neurology 12/2014; 264. DOI:10.1016/j.expneurol.2014.11.009 · 4.62 Impact Factor
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    ABSTRACT: Innate behaviours are observed in naive animals without prior learning or experience, suggesting that the neural circuits that mediate these behaviours are genetically determined and stereotyped. The neural circuits that convey olfactory information from the sense organ to the cortical and subcortical olfactory centres have been anatomically defined, but the specific pathways responsible for innate responses to volatile odours have not been identified. Here we devise genetic strategies that demonstrate that a stereotyped neural circuit that transmits information from the olfactory bulb to cortical amygdala is necessary for innate aversive and appetitive behaviours. Moreover, we use the promoter of the activity-dependent gene arc to express the photosensitive ion channel, channelrhodopsin, in neurons of the cortical amygdala activated by odours that elicit innate behaviours. Optical activation of these neurons leads to appropriate behaviours that recapitulate the responses to innate odours. These data indicate that the cortical amygdala plays a critical role in generating innate odour-driven behaviours but do not preclude its participation in learned olfactory behaviours.
    Nature 11/2014; 515(7526). DOI:10.1038/nature13897 · 42.35 Impact Factor
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    ABSTRACT: Memory traces are believed to be ensembles of cells used to store memories. To visualize memory traces, we created a transgenic line that allows for the comparison between cells activated during encoding and expression of a memory. Mice re-exposed to a fear-inducing context froze more and had a greater percentage of reactivated cells in the dentate gyrus (DG) and CA3 than mice exposed to a novel context. Over time, these differences disappeared, in keeping with the observation that memories become generalized. Optogenetically silencing DG or CA3 cells that were recruited during encoding of a fear-inducing context prevented expression of the corresponding memory. Mice with reduced neurogenesis displayed less contextual memory and less reactivation in CA3 but, surprisingly, normal reactivation in the DG. These studies suggest that distinct memory traces are located in the DG and in CA3 but that the strength of the memory is related to reactivation in CA3. VIDEO ABSTRACT:
    Neuron 07/2014; 83(1):189-201. DOI:10.1016/j.neuron.2014.05.018 · 15.98 Impact Factor
  • Mazen A Kheirbek · René Hen
    Scientific American 07/2014; 311(1):62-7. DOI:10.1038/scientificamerican0714-62 · 1.33 Impact Factor
  • Melody V Wu · René Hen
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    ABSTRACT: Adult-born granule cells in the mammalian dentate gyrus have long been implicated in hippocampal dependent spatial learning and behavioral effects of chronic antidepressant treatment. Although recent anatomical and functional evidence indicates a dissociation of the dorsal and ventral regions of the hippocampus, it is not known if adult neurogenesis within each region specifically contributes to distinct functions or whether adult-born cells along the entire dorsoventral axis are required for these behaviors. We examined the role of distinct subpopulations of adult-born hippocampal granule cells in learning- and anxiety-related behaviors using low-dose focal x-irradiation directed specifically to the dorsal or ventral dentate gyrus. Our findings indicate a functional dissociation between adult-born neurons along the longitudinal axis of the dentate gyrus wherein new neurons in the dorsal dentate gyrus are required for timely acquisition of contextual discrimination while immature neurons in the ventral dentate gyrus are necessary for anxiolytic/antidepressant-related effects of fluoxetine. Interestingly, when contexts are presented with altered temporal cues, or fluoxetine is administered alongside chronic glucocorticoid treatment, this dissociation is abrogated such that adult-born neurons across the entire dorsoventral extent of the dentate gyrus appear to contribute to these behaviors. Our results suggest that individual subpopulations of adult-born hippocampal neurons may be sufficient to mediate distinct behaviors in certain conditions, but are required to act in concert in more challenging situations. © 2014 Wiley Periodicals, Inc.
    Hippocampus 07/2014; 24(7). DOI:10.1002/hipo.22265 · 4.30 Impact Factor
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    ABSTRACT: Modest antidepressant response rates of mood disorders (MD) encourage benzodiazepine (BZD) co-medication with debatable benefit. Adult hippocampal neurogenesis may underlie antidepressant responses, but diazepam co-administration impairs murine neuron maturation and survival in response to fluoxetine. We counted neural progenitor cells (NPCs), mitotic cells, and mature granule neurons post-mortem in dentate gyrus (DG) from subjects with: untreated Diagnostic and Statistical Manual of Mental Disorders (DSM) IV MD (n = 17); antidepressant-treated MD (MD*ADT, n = 10); benzodiazepine-antidepressant-treated MD (MD*ADT*BZD, n = 7); no psychopathology or treatment (controls, n = 18). MD*ADT*BZD had fewer granule neurons vs. MD*ADT in anterior DG and vs. controls in mid DG, and did not differ from untreated-MD in any DG subregion. MD*ADT had more granule neurons than untreated-MD in anterior and mid DG and comparable granule neuron number to controls in all dentate subregions. Untreated-MD had fewer granule neurons than controls in anterior and mid DG, and did not differ from any other group in posterior DG. MD*ADT*BZD had fewer NPCs vs. MD*ADT in mid DG. MD*ADT had more NPCs vs. untreated-MD and controls in anterior and mid DG. MD*ADT*BZD and MD*ADT had more mitotic cells in anterior DG vs. controls and untreated-MD. There were no between-group differences in mid DG in mitotic cells or in posterior DG for any cell type. Our results in mid-dentate, and to some degree anterior dentate, gyrus are consistent with murine findings that benzodiazepines counteract antidepressant-induced increases in neurogenesis by interfering with progenitor proliferation. We also confirmed, in this expanded sample, our previous finding of granule neuron deficit in untreated MD.
    The International Journal of Neuropsychopharmacology 06/2014; 17(12):1-11. DOI:10.1017/S1461145714000844 · 5.26 Impact Factor
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    ABSTRACT: Fear memories guide adaptive behavior in contexts associated with aversive events. The hippocampus forms a neural representation of the context that predicts aversive events. Representations of context incorporate multisensory features of the environment, but must somehow exclude sensory features of the aversive event itself. We investigated this selectivity using cell type-specific imaging and inactivation in hippocampal area CA1 of behaving mice. Aversive stimuli activated CA1 dendrite-targeting interneurons via cholinergic input, leading to inhibition of pyramidal cell distal dendrites receiving aversive sensory excitation from the entorhinal cortex. Inactivating dendrite-targeting interneurons during aversive stimuli increased CA1 pyramidal cell population responses and prevented fear learning. We propose subcortical activation of dendritic inhibition as a mechanism for exclusion of aversive stimuli from hippocampal contextual representations during fear learning.
    Science 02/2014; 343(6173):857-63. DOI:10.1126/science.1247485 · 31.48 Impact Factor
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    ABSTRACT: Adult hippocampal neurogenesis is critically implicated in rodent models of stress and anxiety as well as behavioral effects of antidepressants. While similar factors such as psychiatric disorder and antidepressant administration are correlated with hippocampal volume in humans, the relationship between these factors and adult neurogenesis is less well understood. To better bridge the gap between rodent and human physiology, we examined the numbers of proliferating neural precursors and immature cells in the hippocampal dentate gyrus as well as in vivo MRI-estimated whole hippocampal volume in eight socially dominant- or subordinate-like baboons administered the antidepressant fluoxetine or vehicle. Subordinate-like baboons had lower numbers of proliferating cells and immature neurons than socially dominant-like baboons. Fluoxetine treatment was associated with a larger whole hippocampal volume but surprisingly resulted in lower numbers of immature neurons. These findings are the first to indicate that adult neurogenesis in the baboon hippocampal dentate gyrus may be functionally relevant in the context of social stress and mechanismsof antidepressant action.Neuropsychopharmacology accepted article preview online, 12 February 2014; doi:10.1038/npp.2014.33.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 02/2014; 39(8). DOI:10.1038/npp.2014.33 · 7.83 Impact Factor
  • Zoe. R. Donaldson · René Hen
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    ABSTRACT: Psychiatric genetics research is bidirectional in nature, with human and animal studies becoming more closely integrated as techniques for genetic manipulations allow for more subtle exploration of disease phenotypes. This synergy, however, highlights the importance of considering the way in which we approach the genotype-phenotype relationship. In particular, the nosological divide of psychiatric illness, while clinically relevant, is not directly translatable in animal models. For instance, mice will never fully re-capitulate the broad criteria for many psychiatric disorders; nor will they have guilty ruminations, suicidal thoughts, or rapid speech. Instead, animal models have been and continue to provide a means to explore dimensions of psychiatric disorders in order to identify neural circuits and mechanisms underlying disease-relevant phenotypes. Thus, the genetic investigation of psychiatric illness will yield the greatest insights if efforts continue to identify and utilize biologically valid phenotypes across species. In this review we discuss the progress to date and the future efforts that will enhance translation between human and animal studies, including the identification of intermediate phenotypes that can be studied across species, as well as the importance of refined modeling of human disease-associated genetic variation in mice and other animal models.
    Biological psychiatry 02/2014; 77(1). DOI:10.1016/j.biopsych.2014.02.004 · 9.47 Impact Factor
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    ABSTRACT: Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine are the most common form of medication treatment for major depression. However, approximately 50% of depressed patients fail to achieve an effective treatment response. Understanding how gene expression systems respond to treatments may be critical for understanding antidepressant resistance. We take a novel approach to this problem by demonstrating that the gene expression system of the dentate gyrus responds to fluoxetine (FLX), a commonly used antidepressant medication, in a stereotyped-manner involving changes in the expression levels of thousands of genes. The aggregate behavior of this large-scale systemic response was quantified with principal components analysis (PCA) yielding a single quantitative measure of the global gene expression system state. Quantitative measures of system state were highly correlated with variability in levels of antidepressant-sensitive behaviors in a mouse model of depression treated with fluoxetine. Analysis of dorsal and ventral dentate samples in the same mice indicated that system state co-varied across these regions despite their reported functional differences. Aggregate measures of gene expression system state were very robust and remained unchanged when different microarray data processing algorithms were used and even when completely different sets of gene expression levels were used for their calculation. System state measures provide a robust method to quantify and relate global gene expression system state variability to behavior and treatment. State variability also suggests that the diversity of reported changes in gene expression levels in response to treatments such as fluoxetine may represent different perspectives on unified but noisy global gene expression system state level responses. Studying regulation of gene expression systems at the state level may be useful in guiding new approaches to augmentation of traditional antidepressant treatments.
    PLoS ONE 01/2014; 9(1):e85136. DOI:10.1371/journal.pone.0085136 · 3.23 Impact Factor

Publication Stats

27k Citations
2,804.16 Total Impact Points


  • 1995–2015
    • Columbia University
      • • Department of Pharmacology
      • • Department of Psychiatry
      • • Department of Neuroscience
      • • Center for Neurobiology and Behavior
      New York, New York, United States
    • Howard Hughes Medical Institute
      Ашбърн, Virginia, United States
  • 2000–2014
    • New York State Psychiatric Institute
      • Anxiety Disorders Clinic
      New York, New York, United States
  • 2009
    • Université Paris-Sud 11
      • Faculty of Pharmaceutical Sciences
      Orsay, Île-de-France, France
  • 2005
    • University of Tours
      Tours, Centre, France
  • 2004
    • CUNY Graduate Center
      New York, New York, United States
  • 2002
    • The Children's Hospital of Philadelphia
      • Department of Pediatrics
      Philadelphia, Pennsylvania, United States
  • 2001
    • Université de Montréal
      • Department of Radiology, Radiation Oncology and Nuclear Medicine
      Montréal, Quebec, Canada
    • University of Nantes
      • Faculté de Médecine
      Nantes, Pays de la Loire, France
  • 1995–2001
    • Utrecht University
      • Division of Psychofarmacology
      Utrecht, Utrecht, Netherlands
  • 1986–1995
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France