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Bronk J, Zhang M, Mcaleer M, Mcgovern S, Lassen-Ramshad Y, Safwat A, Daw N, Rainusso N, Mahajan A, Grosshans D, Paulino A. Comprehensive Radiotherapy For Pediatric Ewing Sarcoma: Outcomes of a Prospective Proton Study. Int J Radiat Oncol Biol Phys 2022. [DOI: 10.1016/j.ijrobp.2022.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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2
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Foerde K, Schebendach JE, Davis L, Daw N, Walsh BT, Shohamy D, Steinglass JE. Restrictive eating across a spectrum from healthy to unhealthy: behavioral and neural mechanisms. Psychol Med 2022; 52:1755-1764. [PMID: 33046142 PMCID: PMC8449514 DOI: 10.1017/s0033291720003542] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Restriction of food intake is a central feature of anorexia nervosa (AN) and other eating disorders, yet also occurs in the absence of psychopathology. The neural mechanisms of restrictive eating in health and disease are unclear. METHODS This study examined behavioral and neural mechanisms associated with restrictive eating among individuals with and without eating disorders. Dietary restriction was examined in four groups of women (n = 110): healthy controls, dieting healthy controls, patients with subthreshold (non-low weight) AN, and patients with AN. A Food Choice Task was administered during fMRI scanning to examine neural activation associated with food choices, and a laboratory meal was conducted. RESULTS Behavioral findings distinguished between healthy and ill participants. Healthy individuals, both dieting and non-dieting, chose significantly more high-fat foods than patients with AN or subthreshold AN. Among healthy individuals, choice was primarily influenced by tastiness, whereas, among both patient groups, healthiness played a larger role. Dorsal striatal activation associated with choice was most pronounced among individuals with AN and was significantly associated with selecting fewer high-fat choices in the task and lower caloric intake in the meal the following day. CONCLUSIONS A continuous spectrum of behavior was suggested by the increasing amount of weight loss across groups. Yet, data from this Food Choice Task with fMRI suggest there is a behavioral distinction between illness and health, and that the neural mechanisms underlying food choice in AN are distinct. These behavioral and neural mechanisms of restrictive eating may be useful targets for treatment development.
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Affiliation(s)
- Karin Foerde
- Department of Psychiatry, New York State Psychiatric Institute, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, USA
| | - Janet E. Schebendach
- Department of Psychiatry, Columbia University Irving Medical Center, New York, USA
| | - Lauren Davis
- Department of Psychiatry, New York State Psychiatric Institute, New York, USA
| | - Nathaniel Daw
- Department of Psychology, Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - B. Timothy Walsh
- Department of Psychiatry, New York State Psychiatric Institute, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, USA
| | - Daphna Shohamy
- Psychology Department and Zuckerman Mind Brain and Behavior Institute, Columbia University, New York, USA
| | - Joanna E. Steinglass
- Department of Psychiatry, New York State Psychiatric Institute, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, USA
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3
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Foerde K, Walsh BT, Dalack M, Daw N, Shohamy D, Steinglass JE. Changes in brain and behavior during food-based decision-making following treatment of anorexia nervosa. J Eat Disord 2021; 9:48. [PMID: 33865441 PMCID: PMC8052661 DOI: 10.1186/s40337-021-00402-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/31/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Anorexia nervosa is a severe illness with a high mortality rate, driven in large part by severe and persistent restriction of food intake. A critical challenge is to identify brain mechanisms associated with maladaptive eating behavior and whether they change with treatment. This study tested whether food choice-related caudate activation in anorexia nervosa changes with treatment. METHODS Healthy women (n = 29) and women hospitalized with anorexia nervosa (n = 24), ages 18 to 40 years, completed a Food Choice Task during fMRI scanning at two timepoints. Among patients, procedures occurred upon hospital admission (Time 1) and again after patients had gained to normal weight (Time 2). Healthy controls were tested twice at an interval group-matched to patients. Choice-related caudate activation was assessed at each timepoint, using parametric analyses in an a priori region of interest. RESULTS Among patients, the proportion of high-fat foods selected did not change over time (p's > 0.47), but decreased neural activity in the caudate after treatment was associated with increased selection of high-fat foods (r23 = - 0.43, p = 0.037). Choice-related caudate activation differed among women with anorexia nervosa vs healthy control women at Time 1 (healthy control: M = 0.15 ± 0.87, anorexia nervosa: M = 0.70 ± 1.1, t51 = - 2.05, p = 0.045), but not at Time 2 (healthy control: M = 0.18 ± 1.0, anorexia nervosa: M = 0.37 ± 0.99, t51 = - 0.694, p = 0.49). CONCLUSIONS Caudate activity was more strongly associated with decisions about food among individuals with anorexia nervosa relative to healthy comparison individuals prior to treatment, and decreases in caudate engagement among individuals with anorexia nervosa undergoing treatment were associated with increases in high-fat food choices. The findings underscore the need for treatment development that more successfully alters both eating behavior and the neural mechanisms that guide it.
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Affiliation(s)
- Karin Foerde
- New York State Psychiatric Institute, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA.,Psychiatry Department, Columbia University Irving Medical Center, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA
| | - B Timothy Walsh
- New York State Psychiatric Institute, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA.,Psychiatry Department, Columbia University Irving Medical Center, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA
| | - Maya Dalack
- New York State Psychiatric Institute, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA
| | - Nathaniel Daw
- Princeton Neuroscience Institute, Department of Psychology, Princeton University, Princeton, NJ, 08540, USA
| | - Daphna Shohamy
- Psychology Department and Zuckerman Mind Brain and Behavior Institute, Columbia University, 3227 Broadway, New York, NY, 10027, USA
| | - Joanna E Steinglass
- New York State Psychiatric Institute, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA. .,Psychiatry Department, Columbia University Irving Medical Center, 1051 Riverside Drive, Unit 98, New York, NY, 10032, USA.
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4
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Fung BJ, Qi S, Hassabis D, Daw N, Mobbs D. Slow escape decisions are swayed by trait anxiety. Nat Hum Behav 2019; 3:702-708. [PMID: 31110337 DOI: 10.1038/s41562-019-0595-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 03/25/2019] [Indexed: 12/27/2022]
Abstract
Theoretical models distinguish between neural responses elicited by distal threats and those evoked by more immediate threats1-3. Specifically, slower 'cognitive' fear responses towards distal threats involve a network of brain regions including the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC), while immediate 'reactive' fear responses rely on regions such as the periaqueductal grey4,5. However, it is unclear how anxiety and its neural substrates relate to these distinct defensive survival circuits. We tested whether individual differences in trait anxiety would impact escape behaviour and neural responses to slow and fast attacking predators: conditions designed to evoke cognitive and reactive fear, respectively. Behaviourally, we found that trait anxiety was not related to escape decisions for fast threats, but individuals with higher trait anxiety escaped earlier during slow threats. Functional magnetic resonance imaging showed that when subjects faced slow threats, trait anxiety positively correlated with activity in the vHPC, mPFC, amygdala and insula. Furthermore, the strength of functional coupling between two components of the cognitive circuit-the vHPC and mPFC-was correlated with the degree of trait anxiety. This suggests that anxiety predominantly affects cognitive fear circuits that are involved in volitional strategic escape.
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Affiliation(s)
- Bowen J Fung
- Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA, USA.
| | - Song Qi
- Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA, USA
| | | | - Nathaniel Daw
- Department of Psychology, Princeton University, Princeton, NJ, USA
| | - Dean Mobbs
- Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA, USA.
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5
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Abstract
Flight initiation distance (FID), the distance at which an organism flees from an approaching threat, is an ecological metric of cost-benefit functions of escape decisions. We adapted the FID paradigm to investigate how fast- or slow-attacking "virtual predators" constrain escape decisions. We show that rapid escape decisions rely on "reactive fear" circuits in the periaqueductal gray and midcingulate cortex (MCC), while protracted escape decisions, defined by larger buffer zones, were associated with "cognitive fear" circuits, which include posterior cingulate cortex, hippocampus, and the ventromedial prefrontal cortex, circuits implicated in more complex information processing, cognitive avoidance strategies, and behavioral flexibility. Using a Bayesian decision-making model, we further show that optimization of escape decisions under rapid flight were localized to the MCC, a region involved in adaptive motor control, while the hippocampus is implicated in optimizing decisions that update and control slower escape initiation. These results demonstrate an unexplored link between defensive survival circuits and their role in adaptive escape decisions.
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Affiliation(s)
- Song Qi
- Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA 91106;
- Department of Psychology, Columbia University in the City of New York, New York, NY 10027
| | | | - Jiayin Sun
- Department of Psychology, Columbia University in the City of New York, New York, NY 10027
- School of Humanities and Social Sciences, Harbin Institute of Technology, Heilongjiang 150001, China
| | - Fangjian Guo
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Nathaniel Daw
- Department of Psychology, Princeton University, Princeton, NJ 08544
| | - Dean Mobbs
- Division of the Humanities and Social Sciences, California Institute of Technology, Pasadena, CA 91106;
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Cohen JD, Daw N, Engelhardt B, Hasson U, Li K, Niv Y, Norman KA, Pillow J, Ramadge PJ, Turk-Browne NB, Willke TL. Computational approaches to fMRI analysis. Nat Neurosci 2017; 20:304-313. [PMID: 28230848 DOI: 10.1038/nn.4499] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 01/12/2017] [Indexed: 12/14/2022]
Abstract
Analysis methods in cognitive neuroscience have not always matched the richness of fMRI data. Early methods focused on estimating neural activity within individual voxels or regions, averaged over trials or blocks and modeled separately in each participant. This approach mostly neglected the distributed nature of neural representations over voxels, the continuous dynamics of neural activity during tasks, the statistical benefits of performing joint inference over multiple participants and the value of using predictive models to constrain analysis. Several recent exploratory and theory-driven methods have begun to pursue these opportunities. These methods highlight the importance of computational techniques in fMRI analysis, especially machine learning, algorithmic optimization and parallel computing. Adoption of these techniques is enabling a new generation of experiments and analyses that could transform our understanding of some of the most complex-and distinctly human-signals in the brain: acts of cognition such as thoughts, intentions and memories.
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Affiliation(s)
- Jonathan D Cohen
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
| | - Nathaniel Daw
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
| | - Barbara Engelhardt
- Department of Computer Science, Princeton University, Princeton, New Jersey, USA
| | - Uri Hasson
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
| | - Kai Li
- Department of Computer Science, Princeton University, Princeton, New Jersey, USA
| | - Yael Niv
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
| | - Kenneth A Norman
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
| | - Jonathan Pillow
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
| | - Peter J Ramadge
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey, USA
| | - Nicholas B Turk-Browne
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, USA.,Department of Psychology, Princeton University, Princeton, New Jersey, USA
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7
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Morris LS, Kundu P, Dowell N, Mechelmans DJ, Favre P, Irvine MA, Robbins TW, Daw N, Bullmore ET, Harrison NA, Voon V. Fronto-striatal organization: Defining functional and microstructural substrates of behavioural flexibility. Cortex 2015; 74:118-33. [PMID: 26673945 PMCID: PMC4729321 DOI: 10.1016/j.cortex.2015.11.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 08/17/2015] [Accepted: 11/05/2015] [Indexed: 12/13/2022]
Abstract
Discrete yet overlapping frontal-striatal circuits mediate broadly dissociable cognitive and behavioural processes. Using a recently developed multi-echo resting-state functional MRI (magnetic resonance imaging) sequence with greatly enhanced signal compared to noise ratios, we map frontal cortical functional projections to the striatum and striatal projections through the direct and indirect basal ganglia circuit. We demonstrate distinct limbic (ventromedial prefrontal regions, ventral striatum – VS, ventral tegmental area – VTA), motor (supplementary motor areas – SMAs, putamen, substantia nigra) and cognitive (lateral prefrontal and caudate) functional connectivity. We confirm the functional nature of the cortico-striatal connections, demonstrating correlates of well-established goal-directed behaviour (involving medial orbitofrontal cortex – mOFC and VS), probabilistic reversal learning (lateral orbitofrontal cortex – lOFC and VS) and attentional shifting (dorsolateral prefrontal cortex – dlPFC and VS) while assessing habitual model-free (SMA and putamen) behaviours on an exploratory basis. We further use neurite orientation dispersion and density imaging (NODDI) to show that more goal-directed model-based learning (MBc) is also associated with higher mOFC neurite density and habitual model-free learning (MFc) implicates neurite complexity in the putamen. This data highlights similarities between a computational account of MFc and conventional measures of habit learning. We highlight the intrinsic functional and structural architecture of parallel systems of behavioural control.
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Affiliation(s)
- Laurel S Morris
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom; Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Prantik Kundu
- Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; Section on Functional Imaging Methods, National Institute of Mental Health, Bethesda, MD, USA
| | - Nicholas Dowell
- Department of Psychiatry, Brighton and Sussex Medical School, Brighton, United Kingdom
| | - Daisy J Mechelmans
- Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Pauline Favre
- Laboratory of Psychology and Neurocognition, University Grenoble Alpes, Grenoble, France
| | - Michael A Irvine
- Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Trevor W Robbins
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom; Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom
| | - Nathaniel Daw
- Center for Neural Science and Department of Psychology, New York University, New York, NY, USA
| | - Edward T Bullmore
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom; Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, United Kingdom; NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Neil A Harrison
- Department of Psychiatry, Brighton and Sussex Medical School, Brighton, United Kingdom
| | - Valerie Voon
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom; Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, United Kingdom; NIHR Cambridge Biomedical Research Centre, Cambridge, United Kingdom.
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8
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Norton E, Fleming S, Daw N, Landy M. Criterion Learning in an Orientation-discrimination Task. J Vis 2015. [DOI: 10.1167/15.12.41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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9
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Roy M, Shohamy D, Daw N, Jepma M, Wimmer GE, Wager TD. Representation of aversive prediction errors in the human periaqueductal gray. Nat Neurosci 2014; 17:1607-12. [PMID: 25282614 PMCID: PMC4213247 DOI: 10.1038/nn.3832] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/03/2014] [Indexed: 12/18/2022]
Abstract
Pain is a primary driver of learning and motivated action. It is also a target of learning, as nociceptive brain responses are shaped by learning processes. We combined an instrumental pain avoidance task with an axiomatic approach to assessing fMRI signals related to prediction errors (PEs), which drive reinforcement-based learning. We found that pain PEs were encoded in the periaqueductal gray (PAG), a structure important for pain control and learning in animal models. Axiomatic tests combined with dynamic causal modeling suggested that ventromedial prefrontal cortex, supported by putamen, provides an expected value-related input to the PAG, which then conveys PE signals to prefrontal regions important for behavioral regulation, including orbitofrontal, anterior mid-cingulate and dorsomedial prefrontal cortices. Thus, pain-related learning involves distinct neural circuitry, with implications for behavior and pain dynamics.
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Affiliation(s)
- Mathieu Roy
- 1] Department of Psychology and Neuroscience, University of Colorado, Boulder, Boulder, Colorado, USA. [2] PERFORM Centre, Concordia University, Montreal, Quebec, Canada
| | - Daphna Shohamy
- Department of Psychology, Columbia University, New York, New York, USA
| | - Nathaniel Daw
- Center for Neural Science, New York University, New York, New York, USA
| | - Marieke Jepma
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Boulder, Colorado, USA
| | - G Elliott Wimmer
- 1] Department of Psychology, Columbia University, New York, New York, USA. [2] Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tor D Wager
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Boulder, Colorado, USA
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10
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Zhang H, Daw N, Maloney L. The motor error distribution implicit in planning of movement in a speeded reaching task compared to the true error distribution. J Vis 2012. [DOI: 10.1167/12.9.604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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11
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Zhang H, Daw N, Maloney LT. Testing whether humans have an accurate model of their own motor uncertainty in a speeded reaching task. J Vis 2011. [DOI: 10.1167/11.11.953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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12
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Beeler JA, Daw N, Frazier CRM, Zhuang X. Tonic dopamine modulates exploitation of reward learning. Front Behav Neurosci 2010; 4:170. [PMID: 21120145 PMCID: PMC2991243 DOI: 10.3389/fnbeh.2010.00170] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 10/11/2010] [Indexed: 11/21/2022] Open
Abstract
The impact of dopamine on adaptive behavior in a naturalistic environment is largely unexamined. Experimental work suggests that phasic dopamine is central to reinforcement learning whereas tonic dopamine may modulate performance without altering learning per se; however, this idea has not been developed formally or integrated with computational models of dopamine function. We quantitatively evaluate the role of tonic dopamine in these functions by studying the behavior of hyperdopaminergic DAT knockdown mice in an instrumental task in a semi-naturalistic homecage environment. In this “closed economy” paradigm, subjects earn all of their food by pressing either of two levers, but the relative cost for food on each lever shifts frequently. Compared to wild-type mice, hyperdopaminergic mice allocate more lever presses on high-cost levers, thus working harder to earn a given amount of food and maintain their body weight. However, both groups show a similarly quick reaction to shifts in lever cost, suggesting that the hyperdominergic mice are not slower at detecting changes, as with a learning deficit. We fit the lever choice data using reinforcement learning models to assess the distinction between acquisition and expression the models formalize. In these analyses, hyperdopaminergic mice displayed normal learning from recent reward history but diminished capacity to exploit this learning: a reduced coupling between choice and reward history. These data suggest that dopamine modulates the degree to which prior learning biases action selection and consequently alters the expression of learned, motivated behavior.
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Affiliation(s)
- Jeff A Beeler
- Department of Neurobiology, University of Chicago, Chicago, IL, USA.
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13
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Gläscher J, Daw N, Dayan P, O'Doherty JP. States versus rewards: dissociable neural prediction error signals underlying model-based and model-free reinforcement learning. Neuron 2010; 66:585-95. [PMID: 20510862 DOI: 10.1016/j.neuron.2010.04.016] [Citation(s) in RCA: 670] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2010] [Indexed: 10/19/2022]
Abstract
Reinforcement learning (RL) uses sequential experience with situations ("states") and outcomes to assess actions. Whereas model-free RL uses this experience directly, in the form of a reward prediction error (RPE), model-based RL uses it indirectly, building a model of the state transition and outcome structure of the environment, and evaluating actions by searching this model. A state prediction error (SPE) plays a central role, reporting discrepancies between the current model and the observed state transitions. Using functional magnetic resonance imaging in humans solving a probabilistic Markov decision task, we found the neural signature of an SPE in the intraparietal sulcus and lateral prefrontal cortex, in addition to the previously well-characterized RPE in the ventral striatum. This finding supports the existence of two unique forms of learning signal in humans, which may form the basis of distinct computational strategies for guiding behavior.
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Affiliation(s)
- Jan Gläscher
- Division of Humanities and Social Sciences, California Institute of Technology, Pasadena, CA 91101, USA.
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14
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Landy MS, Daw N, Trommershauser J. Response to changes in variability during movement under risk. J Vis 2010. [DOI: 10.1167/9.8.1099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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15
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Bódi N, Kéri S, Nagy H, Moustafa A, Myers CE, Daw N, Dibó G, Takáts A, Bereczki D, Gluck MA. Reward-learning and the novelty-seeking personality: a between- and within-subjects study of the effects of dopamine agonists on young Parkinson's patients. Brain 2009; 132:2385-95. [PMID: 19416950 DOI: 10.1093/brain/awp094] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Parkinson's disease is characterized by the degeneration of dopaminergic pathways projecting to the striatum. These pathways are implicated in reward prediction. In this study, we investigated reward and punishment processing in young, never-medicated Parkinson's disease patients, recently medicated patients receiving the dopamine receptor agonists pramipexole and ropinirole and healthy controls. The never-medicated patients were also re-evaluated after 12 weeks of treatment with dopamine agonists. Reward and punishment processing was assessed by a feedback-based probabilistic classification task. Personality characteristics were measured by the temperament and character inventory. Results revealed that never-medicated patients with Parkinson's disease showed selective deficits on reward processing and novelty seeking, which were remediated by dopamine agonists. These medications disrupted punishment processing. In addition, dopamine agonists increased the correlation between reward processing and novelty seeking, whereas these drugs decreased the correlation between punishment processing and harm avoidance. Our finding that dopamine agonist administration in young patients with Parkinson's disease resulted in increased novelty seeking, enhanced reward processing, and decreased punishment processing may shed light on the cognitive and personality bases of the impulse control disorders, which arise as side-effects of dopamine agonist therapy in some Parkinson's disease patients.
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Affiliation(s)
- Nikoletta Bódi
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
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16
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Hinds PS, Gattuso JS, Billups C, Rivera C, Quintana J, Daw N. Patient and parent longitudinal reports of quality of life in children and adolescents with osteosarcoma. J Clin Oncol 2007. [DOI: 10.1200/jco.2007.25.18_suppl.19562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
19562 Children and adolescents being treated for osteosarcoma are likely to experience physical, emotional, functional and possibly cognitive changes during the course of their treatment. The aims of this prospective study were to assess the effect of treatment on patients’ quality of life (QoL) at diagnosis and during therapy, compare patient and parent QoL reports, and examine relationships between patient QoL and tumor histologic response to preoperative chemotherapy and event-free survival (EFS) in children and adolescents in treatment for osteosarcoma. Newly diagnosed patients with localized disease completed three established patient reports (Symptom Distress Scale, and PedsQL v.3 and v.4). Parents completed two parent reports (PedsQL v.3 and v.4). QoL evaluations were done at diagnosis, prior to definitive surgery (Week 12), and postoperatively during treatment (Week 23). Sixty-two of 72 eligible patients and their parents completed QoL measures. Symptom distress (SD) decreased in 85% of patients from baseline to Week 12 (with 8/10 symptoms significantly improved) and from baseline to Week 23 in 74% of patients. Improvements in most domains of the PedsQL v. 3 were noted by patient and parent reports from baseline to Weeks 12 and 23 except for the nausea domain. Patient and parent reports differed, with parents reporting lower QoL scores on v. 3 than did patients, particularly in the domains of treatment anxiety, cognitive problems, and communication. QoL scores did not differ by patient gender but did by age in certain domains. Patients reported significant improvements in physical and emotional functioning from baseline to Weeks 12 and 23 using the PedsQL v.4. Parents reported significant improvements in emotional functioning from baseline to Weeks 12 and 23 using the PedsQL v.4. QoL scores were not associated with tumor histologic response or EFS. Significant improvements in QoL domains and in symptoms from diagnosis to Week 12 and to Week 23 were documented in both patient and parent reports. Treatment contributed to improvements in physical and emotional functioning and in symptoms except for nausea. QoL was not related to histologic response or EFS. No significant financial relationships to disclose.
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Affiliation(s)
- P. S. Hinds
- St. Jude Children’s Research Hospital, Memphis, TN; Calvo Mackenna Hospital, Santiago, Chile
| | - J. S. Gattuso
- St. Jude Children’s Research Hospital, Memphis, TN; Calvo Mackenna Hospital, Santiago, Chile
| | - C. Billups
- St. Jude Children’s Research Hospital, Memphis, TN; Calvo Mackenna Hospital, Santiago, Chile
| | - C. Rivera
- St. Jude Children’s Research Hospital, Memphis, TN; Calvo Mackenna Hospital, Santiago, Chile
| | - J. Quintana
- St. Jude Children’s Research Hospital, Memphis, TN; Calvo Mackenna Hospital, Santiago, Chile
| | - N. Daw
- St. Jude Children’s Research Hospital, Memphis, TN; Calvo Mackenna Hospital, Santiago, Chile
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17
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Abstract
Studies on human monetary prediction and decision making emphasize the role of the striatum in encoding prediction errors for financial reward. However, less is known about how the brain encodes financial loss. Using Pavlovian conditioning of visual cues to outcomes that simultaneously incorporate the chance of financial reward and loss, we show that striatal activation reflects positively signed prediction errors for both. Furthermore, we show functional segregation within the striatum, with more anterior regions showing relative selectivity for rewards and more posterior regions for losses. These findings mirror the anteroposterior valence-specific gradient reported in rodents and endorse the role of the striatum in aversive motivational learning about financial losses, illustrating functional and anatomical consistencies with primary aversive outcomes such as pain.
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Affiliation(s)
- Ben Seymour
- Wellcome Trust Centre for Neuroimaging, UCL, London, United Kingdom.
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18
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Abstract
The adjusting-delay task introduced by Mazur (Quantitative analyses of behavior: V. The effect of delay and of intervening events on reinforcement value, 1987, pp. 55-73) has been widely used to study choice of delayed reinforcers. This paradigm involves repeated choice between one reinforcer delivered after a fixed delay and another, typically larger, reinforcer delivered after a variable delay; the variable delay is adjusted depending on the subject's choice until an equilibrium point is reached at which the subject is indifferent between the two alternatives. Rats were trained on a version of this task and their behaviour was examined to determine the nature of their sensitivity to the adjusting delay; these analyses included the use of a cross-correlational technique. No clear evidence of sensitivity to the adjusting delay was found. A number of decision rules, some sensitive to the adjusting delay and some not, were simulated and it was observed that some effects usually supposed to be a consequence of delay sensitivity could be generated by delay-independent processes, such as a consistent, unchanging relative preference between the alternatives. Consequently, the use of explicit analysis of delay sensitivity is advocated in future research on delayed reinforcement.
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19
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Tiffert T, Daw N, Perdomo D, Lew VL. A fast and simple screening test to search for specific inhibitors of the plasma membrane calcium pump. J Lab Clin Med 2001; 137:199-207. [PMID: 11241030 DOI: 10.1067/mlc.2001.113112] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
No specific inhibitors of the plasma membrane Ca(2+) pump have been found to date, limiting research on the particular contribution of this pump to the Ca(2+) homeostasis of animal cells. The search for Ca(2+) pump inhibitors may have been hampered by the lack of an efficient screening method to measure pump activity that would provide an alternative to the lengthy and costly adenosine triphosphatase or Ca(2+)-flux measurements. We propose here a novel screening method in which Ca(2+) pump inhibition is translated into easily measurable cell dehydration. Intact human red cells, suspended in Ca(2+)-containing, low-K(+) buffers were exposed to sequential additions of (1) ionophore A23187 (t = 0) to load the cells with Ca(2+); (2) CoCl(2) (t = 1 minute) to block ionophore-mediated Ca(2+) transport and to allow complete extrusion of the Ca(2+) load by the pump in less than 5 minutes; and (3) NaSCN (t = 6 minutes) to accelerate cell dehydration via Ca(2+)-sensitive K(+) channels when the Ca(2+) load is retained as a result of Ca(2+) pump inhibition. Samples were taken at 10 to 25 minutes after ionophore addition and delivered into hypotonic media containing about 45 mmol/L NaCl. Non-dehydrated cells-with normal, uninhibited pumps-instantly underwent lysis, whereas dehydrated cells-with inhibited pumps-resisted lysis, resulting in translucent or opaque samples, respectively, which were quantifiable by light-absorption measurements. Vanadate was used as a test substance to assess the effect of putative pump inhibitors. This method offers a cost-efficient and easily automated alternative for testing large numbers of natural or synthetic agents.
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Affiliation(s)
- T Tiffert
- Physiological Laboratory, University of Cambridge, United Kingdom
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20
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Lai CM, Robertson T, Papadimitriou J, Shen WY, Daw N, Constable IJ, Rakoczy PE. Controlled production of active cathepsin D in retinal pigment epithelial cells following adenovirus-mediated gene delivery. Mol Ther 2000; 2:476-84. [PMID: 11082321 DOI: 10.1006/mthe.2000.0195] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The transduction of a low cathepsin D-producing retinal pigment epithelial cell line with a recombinant adenovirus, Ad.proCatD, carrying a viral promoter and the precursor form of the lysosomal enzyme cathepsin D, procathepsin D, led to the upregulation of proCatD expression. However, the resultant aspartic protease activity did not exceed that observed in normal primary human retinal pigment epithelial cells. Following the injection of Ad. proCatD into rat eyes, immunohistochemistry and Western blot analysis localized the expression of procathepsin D to the retinal pigment epithelial cell layer and to the sclera/choroid/retinal epithelial cell layers, respectively. This upregulation of procathepsin D expression was accompanied by a limited increase in aspartic protease activity. The injected eyes did not demonstrate any of the retinal changes that have been associated with the overproduction and secretion of active cathepsin D. Immunoelectronmicroscopy of Ad.proCatD-transduced retinal pigment epithelial cells demonstrated the presence of cathepsin D not only in cytoplasmic vesicles and lysosomes but also in the nucleoli and, less strongly, elsewhere in euchromatic regions of some 10% of cells. In spite of the upregulated expression of procathepsin D, the production of active cathepsin D in Ad.proCatD-transduced retinal pigment epithelial cells was strictly controlled. It is proposed that active cathepsin D production is controlled at the point of posttranslational modification by an intranuclear feedback mechanism initiated by the relative excess of procathepsin D in Ad. proCatD-transduced retinal pigment epithelial cells.
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Affiliation(s)
- C M Lai
- Center for Ophthalmology and Visual Science, Lions Eye Institute, Nedlands, 6009, Australia
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21
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Abstract
Cathepsin D is a ubiquitous enzyme which plays an important role in the catabolism of proteins. Enzymatic studies showed that cathepsin D is the most important lysosomal enzyme in the proteolysis of opsin. The importance of cathepsin D in the lysosomal digestion of phagocytosed photoreceptor outer segments by the retinal pigment epithelium suggests that a decrease in cathepsin D activity might contribute to the development of hyalinized drusen and to the development of age-related maculopathy. The aim of this project was to study the immunohistochemical localization of cathepsin D in human eyes and particularly to compare the immunoreactivity of cathepsin D normal retinal pigment epithelial cells and in cells surrounding hyalinized drusen or lesions of age-related maculopathy. Following clinicopathological examinations the eyes were fixed, paraffin embedded and individual sections were subjected to Picro-Mallory staining for histopathological examination. Bleaching was performed then immunohistochemistry was carried out using a monoclonal mouse anti-human cathepsin D antibody. On the basis of the appearance of basal laminar deposit the eyes were divided into five groups corresponding to levels of progression in age-related maculopathy development. Following optimization of bleaching cathepsin D immunostaining was clearly visible in the iris epithelium, ciliary body and the retinal pigment epithelial layer of all eyes with the highest immunoreactivity present in the RPE cells. Within the neural retina the ganglion cells demonstrated a weak signal. Retinal pigment epithelial cathepsin D immunoreactivity was not impaired by age, geographical location or by age-related maculopathy status. There was a small increase in cathepsin D immunoreactivity around hyalinized drusen. The maintenance of cathepsin D immunoreactivity in eyes with hyalinized drusen or in samples with age-related maculopathy suggest that down-regulation of cathepsin D expression in the affected locations does not precede the development of these conditions. However, further studies are required to establish if the immunoreactive cathepsin D represents the fully processed biologically active enzyme.
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Affiliation(s)
- P E Rakoczy
- Molecular Ophthalmology, Centre for Ophthalmology and Visual Science, University of Western Australia, Nedlands, Perth, Australia
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22
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Rakoczy PE, Lai CM, Shen WY, Daw N, Constable IJ. Recombinant adenovirus-mediated gene delivery into the rat retinal pigment epithelium in vivo. Aust N Z J Ophthalmol 1998; 26 Suppl 1:S56-8. [PMID: 9685024 DOI: 10.1111/j.1442-9071.1998.tb01373.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE The present paper describes changes following the subretinal injection of a recombinant replication-deficient adenovirus carrying the beta-galactosidase reporter gene construct into the rat retina. METHODS Ad.RSV.betagal-mediated transduction of rat retinal pigment epithelium (RPE) cells in vitro and in vivo was examined following X-gal staining. RESULTS There was a low level of beta-galactosidase expression in the RPE cells at 4 days postinjection. At 7 days postinjection, a strong transgene expression was present in RPE cells and the expression was maintained at 14 days postinjection. Except for the accumulation of cells at the site of the injection, the morphology of the rest of the retina remained normal. CONCLUSION These results demonstrate that the RPE layer can be successfully targeted for gene delivery in the rat.
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Affiliation(s)
- P E Rakoczy
- Centre of Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Australia.
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Fox K, Daw N, Sato H, Czepita D. The effect of visual experience on development of NMDA receptor synaptic transmission in kitten visual cortex. J Neurosci 1992; 12:2672-84. [PMID: 1351937 PMCID: PMC6575839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023] Open
Abstract
We have studied the effect of dark rearing on the development of excitatory amino acid transmission in 6-week-old kittens. In normal kittens, the NMDA component of the visual response decreases between 3 and 6 weeks of age for cells located in layers IV, V, and VI (Fox et al., 1991). Dark rearing to 6 weeks of age prevents this decrease. Subsequent exposure to light allows the decrease to proceed. Ten days in the light after 6 weeks in the dark was sufficient to decrease the NMDA component of the visual response to the same levels seen in light-reared animals of the same age. Comparison of the effect of the non-NMDA antagonist 6-cyano-7-dinitroquinoxaline-2,3-dione with the NMDA antagonist aminophosphonovalerate showed that the changes were due to the relative contributions of NMDA and non-NMDA receptors to the visual response rather than the overall contribution of glutamate receptors. We also studied the receptive field properties of the cells in the various groups of kittens. Cells given 4 d in the light after 6 weeks in the dark showed increased direction selectivity but little change in response firing rate. After 10 d in the light, visual responses did show some recovery toward adult values, but neither average firing rates nor the proportion of direction-selective cells reached the levels found in normal 6-week-old animals, contrary to the suggestion that a short period in the light can reverse the effect of dark rearing completely. These results show that the decrease in the NMDA component of the visual response seen during normal development of the cortex is caused by visual experience. Changes in NMDA receptors and developmental events such as geniculocortical afferent segregation and acquisition of orientation tuning covary as a function of visual experience rather than age, strongly suggesting that NMDA receptors are involved in experience-dependent developmental processes.
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Affiliation(s)
- K Fox
- Section of Neurobiology, Brown University, Providence, Rhode Island 02912
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24
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Abstract
We have examined the effect of age on the binding of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine maleate (MK-801) in the cat visual cortex. We hypothesized that this binding might change with age because: (1) MK-801 binds to a site associated with the N-methyl-D-aspartate (NMDA) receptor; (2) the NMDA receptor complex has been implicated in neural plasticity; (3) plasticity in the cat visual cortex is age dependent. We used standard receptor binding techniques to measure MK-801 binding in membrane homogenates in cats aged 7 days (d), 21 d, 43 d, 83 d, 7-8 months (mo) and over 2 years. Glutamate (100 microM), glycine (30 microM) and spermidine (20 microM) were used to enhance binding. We found that MK-801 binding is maximal at about 6 weeks of age, decreases slightly by 83 days and then decreases more dramatically in adults. Saturation analysis showed that the of binding with age resulted from variation in number of binding sites and not from variation in affinity. The ability of Mg2+ to inhibit MK-801 binding did not change with age. Dark rearing did not alter the development of MK-801 binding sites.
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Affiliation(s)
- B Gordon
- Institute of Neuroscience, University of Oregon, Eugene 97403
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25
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Abstract
Some features of the visual cortex develop postnatally in mammals. For example, geniculocortical axons that initially overlap throughout cortical layer IV segregate postnatally into two sets of interleaved eye-specific bands. NMDA (N-methyl-D-aspartate) receptors are necessary for eye-specific axon-segregation in the frog tectum, and as NMDA receptors play a greater part in synaptic transmission in early life and decrease in function during the period of axon segregation, they may be involved in the segregation of geniculocortical axons: they are well placed to do so as they transduce retinally derived signals essential for segregation. Rearing animals in the dark in early life delays segregation and prolongs the critical period for plasticity. We now report that dark-rearing of kittens also delays the loss of NMDA receptor function in the visual cortex, supporting the view that they play an important part in neuronal development and plasticity.
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Affiliation(s)
- K Fox
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri 63110
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26
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Abstract
1. A study was made of the relative contribution of N-methyl-D-aspartate (NMDA) and non-NMDA receptors to the visual responses of cells in different layers of the cat visual cortex at different levels of excitatory drive (which was varied by altering the stimulus contrast). 2. Receptive fields were mapped for 121 cells in area 17 of cat cortex. Cells were characterized to determine the optimal visual stimulus, the brightness of which was then varied relative to background luminance to construct a contrast-response (C-R) curve for each cell. Curves were made during control conditions and during application of agonists (NMDA and quisqualate) and/or antagonists [(D)-2-amino-5-phosphonovaleric acid (D-APV) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)] to examine the excitatory amino acid components of the visual response. 3. Threshold responses were obtained with stimuli between 1/60 and 1.8 X background luminance. The cell response, measured by firing rate, was linearly related to stimulus contrast over 1-2 decades and saturated at higher contrasts. 4. Application of APV reduced the slope of the linear portion of the C-R curve for cells located in layers II and III (average reduction, 59% of control). APV did not decrease the threshold to stimulation. The "just suprathreshold" responses to stimulation were reduced by the same proportion as the saturation responses for individual cells. The principal effect was therefore to reduce the gain of the C-R curve in these layers. 5. Application of APV reduced the spontaneous activity of cells located in layers IV, V, and VI with little if any effect on the gain of the C-R curve. This suggests a tonic background level of NMDA-receptor activation in these layers, which is not directly related to the visual response. 6. Low levels of NMDA increased the gain of the C-R curve in layers II/III and V/VI. On the other hand, low levels of quisqualate increased the overall level of firing without affecting the gain of the C-R curve. NMDA did not increase the gain of the curve in layer IV. 7. These experiments show that visual stimuli that produce just suprathreshold responses activate NMDA receptors. The degree of activation is proportionally the same for small responses and large responses for an individual cell. Rather than finding a threshold for NMDA-receptor activation, a continuous range of NMDA-receptor influence was observed over the entire response range.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Fox
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110
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27
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Abstract
GAP-43 levels have been determined by immunoassay in cat visual cortex during postnatal development to test the idea that GAP-43 expression could be related to the duration of the critical period for plasticity. For comparison, GAP-43 levels have also been assayed in primary motor cortex, primary somatosensory cortex, and cerebellum at each age. GAP-43 levels were high in all regions at 5 d (with concentrations ranging from 7-10 ng/microgram protein) and then declined 60-80% by 60 d of age. After 60 d of age, GAP-43 concentrations in each region continued a slow decline to adult values, which ranged from 0.5-2 ng/microgram protein. To test for the involvement of GAP-43 in ocular dominance plasticity during the critical period, the effect of visual deprivation on GAP-43 levels was investigated. Monocular deprivation for 2-7 d, ending at either 27 or 35 d of age, had no effect on total membrane levels of GAP-43. The concentrations of membrane-associated GAP-43 prior to 40 d of age correlate with events that occur during postnatal development of the cat visual cortex. However, the slow decline in membrane-associated GAP-43 levels after 40 d of age may be an index of relative plasticity remaining after the peak of the critical period.
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Affiliation(s)
- H McIntosh
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110
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Fox K, Sato H, Daw N. The location and function of NMDA receptors in cat and kitten visual cortex. J Neurosci 1989; 9:2443-54. [PMID: 2568409 PMCID: PMC6569778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The role of N-methyl-D-aspartate (NMDA) receptors in cat visual cortex was studied as a function of both layer and age by iontophoresis of the NMDA antagonist (D)-2-amino-5-phosphonovaleric acid (APV). Effects on both visual responses and spontaneous activity were observed. In superficial layers (II and III), D-APV reduced visual responses substantially at all ages. Iontophoresis of D-APV with 10 nA of ejecting current for 2-3 min was sufficient to reduce the response to approximately one third of control levels. The magnitude of the reduction did not vary with age. In granular and deep layers (IV, V, and VI), D-APV affected the visual response in young animals but only spontaneous activity in older animals. On average, visual responses were reduced to about half at 20-23 days of age and to about 75% at 4 weeks of age but in most cases were not significantly affected in adults. The rapid change in the functional effect of NMDA receptors over the third and fourth week in granular and deep layers suggests a role in development. There was a reasonable age correlation between the change in effect and the period of geniculocortical afferent segregation. Further experiments will be necessary to determine whether NMDA receptors are necessary for segregation to occur. The presence of an NMDA component to the visual response in the adult in layers II and III argues either that these layers retain some form of plasticity in the adult or that NMDA receptors play a role in the transmission of normal visual input to these layers.
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Affiliation(s)
- K Fox
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110
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29
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Abstract
We have purified a protein that changes in relative concentration during the development of the kitten visual cortex. It resembles GAP-43 (a neuronal protein that is expressed at elevated levels during periods of development and regenerative axon growth) in the following respects: (1) it is an acidic protein (pI = 4.7) whose electrophoretic mobility on SDS-PAGE is similar to, but lower than rat GAP-43, suggesting that the cat protein is larger; (2) its electrophoretic mobility varies with the acrylamide concentration in a manner that is characteristic of GAP-43; (3) its concentration in kitten forebrain is elevated during early postnatal development; (4) the sequence of ten consecutive amino acids from a chemically generated fragment matches the expected sequence from GAP-43; and (5) its amino-acid content also matches GAP-43. We conclude that our purified protein is cat GAP-43. Immunoblots with an antibody prepared against rat GAP-43 suggested that the concentration of GAP-43 in the visual cortex declines with age.
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Affiliation(s)
- H McIntosh
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110
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