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Verhein JR, Vyas S, Shenoy KV. Methylphenidate modulates motor cortical dynamics and behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.15.562405. [PMID: 37905157 PMCID: PMC10614820 DOI: 10.1101/2023.10.15.562405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Methylphenidate (MPH, brand: Ritalin) is a common stimulant used both medically and non-medically. Though typically prescribed for its cognitive effects, MPH also affects movement. While it is known that MPH noncompetitively blocks the reuptake of catecholamines through inhibition of dopamine and norepinephrine transporters, a critical step in exploring how it affects behavior is to understand how MPH directly affects neural activity. This would establish an electrophysiological mechanism of action for MPH. Since we now have biologically-grounded network-level hypotheses regarding how populations of motor cortical neurons plan and execute movements, there is a unique opportunity to make testable predictions regarding how systemic MPH administration - a pharmacological perturbation - might affect neural activity in motor cortex. To that end, we administered clinically-relevant doses of MPH to Rhesus monkeys as they performed an instructed-delay reaching task. Concomitantly, we measured neural activity from dorsal premotor and primary motor cortex. Consistent with our predictions, we found dose-dependent and significant effects on reaction time, trial-by-trial variability, and movement speed. We confirmed our hypotheses that changes in reaction time and variability were accompanied by previously established population-level changes in motor cortical preparatory activity and the condition-independent signal that precedes movements. We expected changes in speed to be a result of changes in the amplitude of motor cortical dynamics and/or a translation of those dynamics in activity space. Instead, our data are consistent with a mechanism whereby the neuromodulatory effect of MPH is to increase the gain and/or the signal-to-noise of motor cortical dynamics during reaching. Continued work in this domain to better understand the brain-wide electrophysiological mechanism of action of MPH and other psychoactive drugs could facilitate more targeted treatments for a host of cognitive-motor disorders.
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Affiliation(s)
- Jessica R Verhein
- Medical Scientist Training Program, Stanford School of Medicine, Stanford University, Stanford, CA
- Neurosciences Graduate Program, Stanford School of Medicine, Stanford University, Stanford, CA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA
- Current affiliations: Psychiatry Research Residency Training Program, University of California, San Francisco, San Francisco, CA
| | - Saurabh Vyas
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA
- Department of Bioengineering, Stanford University, Stanford, CA
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY
| | - Krishna V Shenoy
- Neurosciences Graduate Program, Stanford School of Medicine, Stanford University, Stanford, CA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA
- Department of Bioengineering, Stanford University, Stanford, CA
- Department of Electrical Engineering, Stanford University, Stanford, CA
- Howard Hughes Medical Institute at Stanford University, Stanford, CA
- Department of Neurobiology, Stanford University, Stanford, CA
- Bio-X Program, Stanford University, Stanford, CA
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Burk DC, Taswell C, Tang H, Averbeck BB. Computational mechanisms underlying motivation to earn symbolic reinforcers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.11.561900. [PMID: 37873311 PMCID: PMC10592730 DOI: 10.1101/2023.10.11.561900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Reinforcement learning (RL) is a theoretical framework that describes how agents learn to select options that maximize rewards and minimize punishments over time. We often make choices, however, to obtain symbolic reinforcers (e.g. money, points) that can later be exchanged for primary reinforcers (e.g. food, drink). Although symbolic reinforcers are motivating, little is understood about the neural or computational mechanisms underlying the motivation to earn them. In the present study, we examined how monkeys learn to make choices that maximize fluid rewards through reinforcement with tokens. The question addressed here is how the value of a state, which is a function of multiple task features (e.g. current number of accumulated tokens, choice options, task epoch, trials since last delivery of primary reinforcer, etc.), drives value and affects motivation. We constructed a Markov decision process model that computes the value of task states given task features to capture the motivational state of the animal. Fixation times, choice reaction times, and abort frequency were all significantly related to values of task states during the tokens task (n=5 monkeys). Furthermore, the model makes predictions for how neural responses could change on a moment-by-moment basis relative to changes in state value. Together, this task and model allow us to capture learning and behavior related to symbolic reinforcement.
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Affiliation(s)
- Diana C. Burk
- Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda MD, 20892-4415
| | - Craig Taswell
- Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda MD, 20892-4415
| | - Hua Tang
- Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda MD, 20892-4415
| | - Bruno B. Averbeck
- Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda MD, 20892-4415
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Ni AM, Bowes BS, Ruff DA, Cohen MR. Methylphenidate as a causal test of translational and basic neural coding hypotheses. Proc Natl Acad Sci U S A 2022; 119:e2120529119. [PMID: 35467980 PMCID: PMC9169912 DOI: 10.1073/pnas.2120529119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 03/17/2022] [Indexed: 11/18/2022] Open
Abstract
Most systems neuroscience studies fall into one of two categories: basic science work aimed at understanding the relationship between neurons and behavior, or translational work aimed at developing treatments for neuropsychiatric disorders. Here we use these two approaches to inform and enhance each other. Our study both tests hypotheses about basic science neural coding principles and elucidates the neuronal mechanisms underlying clinically relevant behavioral effects of systemically administered methylphenidate (Ritalin). We discovered that orally administered methylphenidate, used clinically to treat attention deficit hyperactivity disorder (ADHD) and generally to enhance cognition, increases spatially selective visual attention, enhancing visual performance at only the attended location. Further, we found that this causal manipulation enhances vision in rhesus macaques specifically when it decreases the mean correlated variability of neurons in visual area V4. Our findings demonstrate that the visual system is a platform for understanding the neural underpinnings of both complex cognitive processes (basic science) and neuropsychiatric disorders (translation). Addressing basic science hypotheses, our results are consistent with a scenario in which methylphenidate has cognitively specific effects by working through naturally selective cognitive mechanisms. Clinically, our findings suggest that the often staggeringly specific symptoms of neuropsychiatric disorders may be caused and treated by leveraging general mechanisms.
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Affiliation(s)
- Amy M. Ni
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260
| | - Brittany S. Bowes
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260
| | - Douglas A. Ruff
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260
| | - Marlene R. Cohen
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260
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Bowman-Smart, Hilary, Savulescu, Julian. The Ethics of Motivational Neuro-Doping in Sport: Praiseworthiness and Prizeworthiness. NEUROETHICS-NETH 2021; 14:205-215. [PMID: 34790275 PMCID: PMC8590656 DOI: 10.1007/s12152-020-09445-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/08/2020] [Indexed: 11/28/2022]
Abstract
Motivational enhancement in sport – a form of ‘neuro-doping’ – can help athletes attain greater achievements in sport. A key question is whether or not that athlete deserves that achievement. We distinguish three concepts – praiseworthiness (whether the athlete deserves praise), prizeworthiness (whether the athlete deserves the prize), and admiration (pure admiration at the performance) – which are closely related. However, in sport, they can come apart. The most praiseworthy athlete may not be the most prizeworthy, and so on. Using a model of praiseworthiness as costly commitment to a valuable end, and situating prizeworthiness within the boundaries of the sport, we argue that motivational enhancement in some cases can be compatible with desert.
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Affiliation(s)
- Bowman-Smart
- Biomedical Ethics Research Group, Murdoch Children's Research Institute 50, Rd Parkville VIC 3052, Flemington, Victoria 3052 Australia.,Department of Paediatrics, University of Melbourne, Parkville, Victoria 3010 Australia.,Uehiro Centre for Practical Ethics, University of Oxford, St Ebbes St, Oxford, OX1 1PT UK
| | - Hilary
- Biomedical Ethics Research Group, Murdoch Children's Research Institute 50, Rd Parkville VIC 3052, Flemington, Victoria 3052 Australia.,Department of Paediatrics, University of Melbourne, Parkville, Victoria 3010 Australia
| | - Savulescu
- Biomedical Ethics Research Group, Murdoch Children's Research Institute 50, Rd Parkville VIC 3052, Flemington, Victoria 3052 Australia.,Department of Paediatrics, University of Melbourne, Parkville, Victoria 3010 Australia.,Uehiro Centre for Practical Ethics, University of Oxford, St Ebbes St, Oxford, OX1 1PT UK
| | - Julian
- Biomedical Ethics Research Group, Murdoch Children's Research Institute 50, Rd Parkville VIC 3052, Flemington, Victoria 3052 Australia.,Uehiro Centre for Practical Ethics, University of Oxford, St Ebbes St, Oxford, OX1 1PT UK
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Lacourt TE, Heijnen CJ, Manzullo EF, Escalante C. A central role for apathy in the effectiveness of interventions for cancer-related fatigue. Psychooncology 2020; 29:1613-1619. [PMID: 32658377 PMCID: PMC10406137 DOI: 10.1002/pon.5476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 07/01/2020] [Accepted: 07/07/2020] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Cancer-related fatigue (CRF) affects a substantial number of cancer patients and survivors. Recommendations for CRF treatments are largely based on results of randomized controlled trials. The interpretability of such results is limited to patients eligible and willing to participate in these trials. We aimed to address this limitation in a retrospective study of patients seen at a CRF clinic in a comprehensive cancer center. The objectives were to (a) determine the effectiveness of clinician-initiated interventions for CRF and identify their mediators and (b) describe the frequency and effectiveness of patient-initiated physical activity (PA) behavior for alleviating CRF and identify determinants of this PA. METHODS Data (patient-reported somatic and mood symptoms; clinical data; clinician-documented changes in medication and behavior) from n = 213 patients collected as part of the clinic's standard of care at initial clinical consult and follow-up 4 to 11 weeks later were included. Effects of clinician-initiated interventions and patient-initiated PA on change in fatigue were analyzed using linear models. RESULTS Of all clinician-initiated interventions, only psychostimulant start was recorded frequent enough for further investigation and was associated with reduced fatigue; this association was mediated by a reduction in apathy. PA was also associated with reduced fatigue severity. PA initiation/increase after consult was associated with lower apathy at consult. CONCLUSIONS These results demonstrate a major role for patient apathy in the effectiveness and initiation of CRF-targeting interventions. Behavioral therapies focusing on reduction in apathy should be considered as initial treatment of CRF in those with substantial apathy.
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Affiliation(s)
- Tamara E Lacourt
- Department of Psychiatry, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.,Department of Symptom Research, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Cobi J Heijnen
- Department of Symptom Research, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Ellen F Manzullo
- Department of General Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Carmen Escalante
- Department of General Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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Maldonado EF, Nislin M, Martínez-Escribano A, Marín L, Enguix A, Alamo A, López C, Magarín A, Ortíz P, Muñoz M, García S. Association of salivary alpha-amylase and salivary flow rate with working memory functioning in healthy children. Stress 2019; 22:670-678. [PMID: 31084229 DOI: 10.1080/10253890.2019.1611777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The aim of this study was to examine the association between auditory and visual working memory (WM) performance and salivary alpha-amylase (sAA) and salivary flow rate (SFR) in a sample of 63 children (38 boys). WM was assessed by means of WISC-V subtests: four auditory subtests (Digit Span and Letter-Number Sequencing) and one visual subtest (Picture Span). SAA activity, output, and SFR were measured at baseline (10 min prior to testing), one minute prior to testing, one minute after the end of the auditory WM subtests and one minute after the end of the visual WM subtest. Our statistical analyses showed an association among SAA activity, output and SFR levels and the number of recalled digits in the last attempt score in Letter-Number Sequencing subtest. Specifically, our results showed that working performance in this task was associated with a concurrent decrease in SFR (r(63) = -0.423, p < .05). This salivary measure was the best predictor of this specific index of working memory performance (β = -0.423, p < .05). These results show that the changes in SFR, which represents changes in parasympathetic tone, could be employed in future studies as a noninvasive marker of working memory performance in child studies.
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Affiliation(s)
| | - Mari Nislin
- Faculty of Education and Human Development, The Education University of Hong Kong , Hong Kong , China
| | | | - Laura Marín
- Department of Clinical Analysis, Virgen de la Victoria Hospital , Malaga , Spain
| | - Alfredo Enguix
- Department of Clinical Analysis, Virgen de la Victoria Hospital , Malaga , Spain
| | - Ana Alamo
- Clinical Neuropsychology Laboratory, School of Psychology, University of Malaga , Malaga , Spain
| | - Cristina López
- Clinical Neuropsychology Laboratory, School of Psychology, University of Malaga , Malaga , Spain
| | - Alba Magarín
- Clinical Neuropsychology Laboratory, School of Psychology, University of Malaga , Malaga , Spain
| | - Paula Ortíz
- Clinical Neuropsychology Laboratory, School of Psychology, University of Malaga , Malaga , Spain
| | - Marina Muñoz
- Clinical Neuropsychology Laboratory, School of Psychology, University of Malaga , Malaga , Spain
| | - Silvia García
- Clinical Neuropsychology Laboratory, School of Psychology, University of Malaga , Malaga , Spain
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Standage D, Paré M. Slot-like capacity and resource-like coding in a neural model of multiple-item working memory. J Neurophysiol 2018; 120:1945-1961. [PMID: 29947585 DOI: 10.1152/jn.00778.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
For the past decade, research on the storage limitations of working memory has been dominated by two fundamentally different hypotheses. On the one hand, the contents of working memory may be stored in a limited number of "slots," each with a fixed resolution. On the other hand, any number of items may be stored but with decreasing resolution. These two hypotheses have been invaluable in characterizing the computational structure of working memory, but neither provides a complete account of the available experimental data or speaks to the neural basis of the limitations it characterizes. To address these shortcomings, we simulated a multiple-item working memory task with a cortical network model, the cellular resolution of which allowed us to quantify the coding fidelity of memoranda as a function of memory load, as measured by the discriminability, regularity, and reliability of simulated neural spiking. Our simulations account for a wealth of neural and behavioral data from human and nonhuman primate studies, and they demonstrate that feedback inhibition lowers both capacity and coding fidelity. Because the strength of inhibition scales with the number of items stored by the network, increasing this number progressively lowers fidelity until capacity is reached. Crucially, the model makes specific, testable predictions for neural activity on multiple-item working memory tasks. NEW & NOTEWORTHY Working memory is the ability to keep information in mind and is fundamental to cognition. It is actively debated whether the storage limitations of working memory reflect a small number of storage units (slots) or a decrease in coding resolution as a limited resource is allocated to more items. In a cortical model, we found that slot-like capacity and resource-like neural coding resulted from the same mechanism, offering an integrated explanation for storage limitations.
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Affiliation(s)
- Dominic Standage
- Centre for Neuroscience Studies, Queen's University , Kingston, Ontario , Canada
| | - Martin Paré
- Centre for Neuroscience Studies, Queen's University , Kingston, Ontario , Canada
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Kristofova M, Aher YD, Ilic M, Radoman B, Kalaba P, Dragacevic V, Aher NY, Leban J, Korz V, Zanon L, Neuhaus W, Wieder M, Langer T, Urban E, Sitte HH, Hoeger H, Lubec G, Aradska J. A daily single dose of a novel modafinil analogue CE-123 improves memory acquisition and memory retrieval. Behav Brain Res 2018; 343:83-94. [PMID: 29410048 DOI: 10.1016/j.bbr.2018.01.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/28/2018] [Accepted: 01/29/2018] [Indexed: 01/25/2023]
Abstract
Dopamine reuptake inhibitors have been shown to improve cognitive parameters in various tasks and animal models. We recently reported a series of modafinil analogues, of which the most promising, 5-((benzhydrylsulfinyl)methyl) thiazole (CE-123), was selected for further development. The present study aims to characterize pharmacological properties of CE-123 and to investigate the potential to enhance memory performance in a rat model. In vitro transporter assays were performed in cells expressing human transporters. CE-123 blocked uptake of [3H] dopamine (IC50 = 4.606 μM) while effects on serotonin (SERT) and the norepinephrine transporter (NET) were negligible. Blood-brain barrier and pharmacokinetic studies showed that the compound reached the brain and lower elimination than R-modafinil. The Pro-cognitive effect was evaluated in a spatial hole-board task in male Sprague-Dawley rats and CE-123 enhances memory acquisition and memory retrieval, represented by significantly increased reference memory indices and shortened latency. Since DAT blockers can be considered as indirect dopamine receptor agonists, western blotting was used to quantify protein levels of dopamine receptors D1R, D2R and D5R and DAT in the synaptosomal fraction of hippocampal subregions CA1, CA3 and dentate gyrus (DG). CE-123 administration in rats increased total DAT levels and D1R protein levels were significantly increased in CA1 and CA3 in treated/trained groups. The increase of D5R was observed in DG only. Dopamine receptors, particularly D1R, seem to play a role in mediating CE-123-induced memory enhancement. Dopamine reuptake inhibition by CE-123 may represent a novel and improved stimulant therapeutic for impairments of cognitive functions.
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Affiliation(s)
- Martina Kristofova
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Yogesh D Aher
- Department of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Marija Ilic
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Bojana Radoman
- Department of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Predrag Kalaba
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Vladimir Dragacevic
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Nilima Y Aher
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Johann Leban
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Volker Korz
- Department of Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Lisa Zanon
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Winfried Neuhaus
- Competence Unit Molecular Diagnostics, Competence Center Health and Bioresources, Austrian Institute of Technology (AIT) GmbH, Vienna, Austria
| | - Marcus Wieder
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Thierry Langer
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Ernst Urban
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Harald Hoeger
- Core Unit of Biomedical Research, Division of Laboratory Animal Science and Genetics, Medical University of Vienna, Himberg, Austria
| | - Gert Lubec
- Department of Neuroproteomics, Paracelsus Medical University, Salzburg, Austria.
| | - Jana Aradska
- Department of Neuroproteomics, Paracelsus Medical University, Salzburg, Austria.
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