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Farrell MR, Esteban JSD, Faget L, Floresco SB, Hnasko TS, Mahler SV. Ventral Pallidum GABA Neurons Mediate Motivation Underlying Risky Choice. J Neurosci 2021; 41:4500-4513. [PMID: 33837052 PMCID: PMC8152612 DOI: 10.1523/jneurosci.2039-20.2021] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 02/01/2021] [Accepted: 02/12/2021] [Indexed: 12/29/2022] Open
Abstract
Pursuing rewards while avoiding danger is an essential function of any nervous system. Here, we examine a new mechanism helping rats negotiate the balance between risk and reward when making high-stakes decisions. Specifically, we focus on GABA neurons within an emerging mesolimbic circuit nexus: the ventral pallidum (VP). These neurons play a distinct role from other VP neurons in simple motivated behaviors in mice, but their role in more complex motivated behaviors is unknown. Here, we interrogate the behavioral functions of VPGABA neurons in male and female transgenic GAD1:Cre rats (and WT littermates), using a reversible chemogenetic inhibition approach. Using a behavioral assay of risky decision-making, and of the food-seeking and shock-avoidance components of this task, we show that engaging inhibitory Gi/o signaling specifically in VPGABA neurons suppresses motivation to pursue highly salient palatable foods, and possibly also motivation to avoid being shocked. In contrast, inhibiting these neurons did not affect seeking of low-value food, free consumption of palatable food, or unconditioned affective responses to shock. Accordingly, when rats considered whether to pursue food despite potential for shock in a risky decision-making task, inhibiting VPGABA neurons caused them to more readily select a small but safe reward over a large but dangerous one, an effect not seen in the absence of shock threat. Together, results indicate that VPGABA neurons are critical for high-stakes adaptive responding that is necessary for survival, but which may also malfunction in psychiatric disorders.SIGNIFICANCE STATEMENT In a dynamic world, it is essential to implement appropriate behaviors under circumstances involving rewards, threats, or both. Here, we demonstrate a crucial role for VPGABA neurons in high-stakes motivated behavior of several types. We show that this VPGABA role in motivation impacts decision-making, as inhibiting these neurons yields a conservative, risk-averse strategy not seen when the task is performed without threat of shock. These new roles for VPGABA neurons in behavior may inform future strategies for treating addiction, and other disorders of maladaptive decision-making.
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Affiliation(s)
- Mitchell R Farrell
- Department of Neurobiology & Behavior, University of California, Irvine, California 92697
| | | | - Lauren Faget
- Department of Neurosciences, University of California, San Diego, California 92093
| | - Stan B Floresco
- Department of Psychology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Thomas S Hnasko
- Department of Neurosciences, University of California, San Diego, California 92093
- VASDHS Research Service, San Diego, California 92161
| | - Stephen V Mahler
- Department of Neurobiology & Behavior, University of California, Irvine, California 92697
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2
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Mathis V, Barbelivien A, Majchrzak M, Mathis C, Cassel JC, Lecourtier L. The Lateral Habenula as a Relay of Cortical Information to Process Working Memory. Cereb Cortex 2018; 27:5485-5495. [PMID: 28334072 DOI: 10.1093/cercor/bhw316] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/19/2016] [Indexed: 11/14/2022] Open
Abstract
Working memory is a cognitive ability allowing the temporary storage of information to solve problems or adjust behavior. While working memory is known to mainly depend on the medial prefrontal cortex (mPFC), very few is known about how cortical information are relayed subcortically. By its connectivity, the lateral habenula (lHb) might act as a subcortical relay for cortical information. Indeed, the lHb receives inputs from several mPFC subregions, and recent findings suggest a role for the lHb in online processing of spatial information, a fundamental aspect of working memory. In rats, in a delayed non-matching to position paradigm, using focal microinjections of the GABAA agonist muscimol we showed that inactivation of the lHb (16 ng in 0.2 µL per side), as well as disconnection between the prelimbic region of the mPFC (mPFC/PrL, 32 ng in 0.4 µL in one hemisphere) and the lHb (16 ng in 0.2 µL in the lHb in the contralateral hemisphere) impaired working memory. The deficits were unlikely to result from motivational or motor deficits as muscimol did not affect reward collection or cue responding latencies, and did not increase the number of omissions. These results show for the first time the implication of the lHb in mPFC-dependent memory processes, likely as a relay of mPFC/PrL information. They also open new perspectives in the understanding of the top-down processing of high-level cognitive functions.
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Affiliation(s)
- Victor Mathis
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, F-67000 Strasbourg, France.,LNCA, UMR 7364, CNRS, F-67000 Strasbourg, France
| | - Alexandra Barbelivien
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, F-67000 Strasbourg, France.,LNCA, UMR 7364, CNRS, F-67000 Strasbourg, France
| | - Monique Majchrzak
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, F-67000 Strasbourg, France.,LNCA, UMR 7364, CNRS, F-67000 Strasbourg, France
| | - Chantal Mathis
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, F-67000 Strasbourg, France.,LNCA, UMR 7364, CNRS, F-67000 Strasbourg, France
| | - Jean-Christophe Cassel
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, F-67000 Strasbourg, France.,LNCA, UMR 7364, CNRS, F-67000 Strasbourg, France
| | - Lucas Lecourtier
- Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Université de Strasbourg, F-67000 Strasbourg, France.,LNCA, UMR 7364, CNRS, F-67000 Strasbourg, France
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3
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Chang SE, Smedley EB, Stansfield KJ, Stott JJ, Smith KS. Optogenetic Inhibition of Ventral Pallidum Neurons Impairs Context-Driven Salt Seeking. J Neurosci 2017; 37:5670-5680. [PMID: 28495976 PMCID: PMC5469304 DOI: 10.1523/jneurosci.2968-16.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 04/28/2017] [Accepted: 05/02/2017] [Indexed: 01/10/2023] Open
Abstract
Salt appetite, in which animals can immediately seek out salt when under a novel state of sodium deprivation, is a classic example of how homeostatic systems interface with learned associations to produce an on-the-fly updating of motivated behavior. Neural activity in the ventral pallidum (VP) has been shown to encode changes in the value of salt under such conditions, both the value of salt itself (Tindell et al., 2006) and the motivational value of its predictive cues (Tindell et al., 2009; Robinson and Berridge, 2013). However, it is not known whether the VP is necessary for salt appetite in terms of seeking out salt or consuming salt following sodium depletion. Here, we used a conditioned place-preference procedure to investigate the effects of optogenetically inhibiting the VP on context-driven salt seeking and the consumption of salt following deprivation. Male rats learned to associate one context with sucrose and another context with less-desirable salt. Following sodium depletion, and in the absence of either sucrose or salt, we found that inhibiting the VP selectively reduced the elevation in time spent in the salt-paired context. VP inhibition had minimal effects on the consumption of salt once it was made available. To our knowledge, this is the first evidence that the VP or any brain region is necessary for the ability to use contextual cues to guide salt seeking. These results highlight a dissociation between deficit-driven reward seeking and reward consumption to replenish those deficits, with the former process being particularly sensitive to on-line VP activity.SIGNIFICANCE STATEMENT Salt appetite, in which rats will immediately seek out a once-undesirable concentrated salt solution after being depleted of bodily sodium despite never having tasted salt as a positive reward, is a phenomenon showing how animals can update their motivational goals without any new learning or conditioning. This salt-seeking behavior is also observed when the animal is presented with salt-paired cues. The neural circuitry necessary for context-driven salt-seeking behavior is unknown. We used a novel conditioned place preference procedure to show that optogenetic inhibition of the ventral pallidum (VP), a region known for processing reward, impairs context-driven salt seeking and has minimal effects on the consumption of salt itself following sodium depletion. These results highlight the importance of the VP in context-driven reward-seeking behavior.
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Affiliation(s)
- Stephen E Chang
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, and
| | - Elizabeth B Smedley
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, and
| | - Katherine J Stansfield
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309
| | - Jeffrey J Stott
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, and
| | - Kyle S Smith
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, and
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4
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Role of D2 dopamine receptors of the ventral pallidum in inhibitory avoidance learning. Behav Brain Res 2017; 321:99-105. [DOI: 10.1016/j.bbr.2017.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/13/2016] [Accepted: 01/01/2017] [Indexed: 11/21/2022]
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Role of ventral pallidal D2 dopamine receptors in the consolidation of spatial memory. Behav Brain Res 2016; 313:1-9. [DOI: 10.1016/j.bbr.2016.07.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 06/30/2016] [Accepted: 07/04/2016] [Indexed: 11/18/2022]
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Root DH, Melendez RI, Zaborszky L, Napier TC. The ventral pallidum: Subregion-specific functional anatomy and roles in motivated behaviors. Prog Neurobiol 2015; 130:29-70. [PMID: 25857550 PMCID: PMC4687907 DOI: 10.1016/j.pneurobio.2015.03.005] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 03/19/2015] [Accepted: 03/29/2015] [Indexed: 12/17/2022]
Abstract
The ventral pallidum (VP) plays a critical role in the processing and execution of motivated behaviors. Yet this brain region is often overlooked in published discussions of the neurobiology of mental health (e.g., addiction, depression). This contributes to a gap in understanding the neurobiological mechanisms of psychiatric disorders. This review is presented to help bridge the gap by providing a resource for current knowledge of VP anatomy, projection patterns and subregional circuits, and how this organization relates to the function of VP neurons and ultimately behavior. For example, ventromedial (VPvm) and dorsolateral (VPdl) VP subregions receive projections from nucleus accumbens shell and core, respectively. Inhibitory GABAergic neurons of the VPvm project to mediodorsal thalamus, lateral hypothalamus, and ventral tegmental area, and this VP subregion helps discriminate the appropriate conditions to acquire natural rewards or drugs of abuse, consume preferred foods, and perform working memory tasks. GABAergic neurons of the VPdl project to subthalamic nucleus and substantia nigra pars reticulata, and this VP subregion is modulated by, and is necessary for, drug-seeking behavior. Additional circuits arise from nonGABAergic neuronal phenotypes that are likely to excite rather than inhibit their targets. These subregional and neuronal phenotypic circuits place the VP in a unique position to process motivationally relevant stimuli and coherent adaptive behaviors.
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Affiliation(s)
- David H Root
- Department of Psychology, Rutgers University, 152 Frelinghuysen Road, New Brunswick, NJ 08854, United States.
| | - Roberto I Melendez
- Department of Anatomy and Neurobiology, University of Puerto Rico School of Medicine, San Juan, PR 00936, United States.
| | - Laszlo Zaborszky
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, 197 University Avenue, Newark, NJ 07102, United States.
| | - T Celeste Napier
- Departments of Pharmacology and Psychiatry, Center for Compulsive Behavior and Addiction, Rush University Medical Center, Chicago, IL 60612, United States.
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Abstract
Foraging- and feeding-related behaviors across eumetazoans share similar molecular mechanisms, suggesting the early evolution of an optimal foraging behavior called area-restricted search (ARS), involving mechanisms of dopamine and glutamate in the modulation of behavioral focus. Similar mechanisms in the vertebrate basal ganglia control motor behavior and cognition and reveal an evolutionary progression toward increasing internal connections between prefrontal cortex and striatum in moving from amphibian to primate. The basal ganglia in higher vertebrates show the ability to transfer dopaminergic activity from unconditioned stimuli to conditioned stimuli. The evolutionary role of dopamine in the modulation of goal-directed behavior and cognition is further supported by pathologies of human goal-directed cognition, which have motor and cognitive dysfunction and organize themselves, with respect to dopaminergic activity, along the gradient described by ARS, from perseverative to unfocused. The evidence strongly supports the evolution of goal-directed cognition out of mechanisms initially in control of spatial foraging but, through increasing cortical connections, eventually used to forage for information.
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Affiliation(s)
- Thomas T Hills
- Department of Psychological and Brain Sciences, Indiana University
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8
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Spencer RC, Klein RM, Berridge CW. Psychostimulants act within the prefrontal cortex to improve cognitive function. Biol Psychiatry 2012; 72:221-7. [PMID: 22209638 PMCID: PMC3319517 DOI: 10.1016/j.biopsych.2011.12.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 11/18/2011] [Accepted: 12/02/2011] [Indexed: 11/27/2022]
Abstract
BACKGROUND At low and clinically relevant doses, psychostimulants enhance cognitive and behavioral function dependent on the prefrontal cortex (PFC) and extended frontostriatal circuitry. These actions are observed in individuals with attention-deficit/hyperactivity disorder, as well as in normal human and animal subjects. Despite the widespread use of these drugs, the sites of action involved in their cognition-enhancing and therapeutic effects are poorly understood. Indirect and/or correlative evidence suggests the cognition-enhancing/therapeutic effects of psychostimulants may involve actions directly within the PFC or extended frontostriatal circuitry. The current studies examined the degree to which methylphenidate (MPH) (Ritalin) acts within distinct frontostriatal subfields to improve PFC-dependent cognition as measured in a delayed-response test of spatial working memory. METHODS Working memory performance was assessed following microinfusion of vehicle or varying doses of MPH (.03-8.0 μg/500 nL) directly into the dorsomedial PFC (dorsal prelimbic and dorsal anterior cingulate cortex), the ventromedial PFC (infralimbic), and the dorsomedial striatum of rats (n = 69). RESULTS Methylphenidate infusion into the dorsomedial PFC, but not ventromedial PFC, elicited an inverted U-shaped facilitation of PFC-dependent cognition as measured in this task. The magnitude of this improvement was comparable with that seen with systemic administration. Additional studies demonstrated that although the dorsomedial striatum is necessary for accurate performance in this task, MPH infusion into this region did not affect working memory performance. CONCLUSIONS These observations provide the first definitive evidence that the PFC is a site of action in the cognition-enhancing and presumably therapeutic actions of low-dose psychostimulants.
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9
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Martig AK, Jones GL, Smith KE, Mizumori SJY. Context dependent effects of ventral tegmental area inactivation on spatial working memory. Behav Brain Res 2009; 203:316-20. [PMID: 19447146 DOI: 10.1016/j.bbr.2009.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 04/28/2009] [Accepted: 05/04/2009] [Indexed: 12/01/2022]
Abstract
Rats were tested on a hippocampus dependent win-shift working memory task in familiar or novel environments after receiving bilateral ventral tegmental area infusions of baclofen. Baclofen infusion disrupted working memory performance in both familiar and novel environments. In addition, baclofen infusion selectively disrupted short-term working memory in the novel environment. This experiment confirms selective ventral tegmental area support of accurate performance during a context dependent spatial navigation task.
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Affiliation(s)
- Adria K Martig
- Psychology Department, Box 351525, University of Washington, Seattle, WA 98195-1525, United States
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Smith KS, Tindell AJ, Aldridge JW, Berridge KC. Ventral pallidum roles in reward and motivation. Behav Brain Res 2008; 196:155-67. [PMID: 18955088 DOI: 10.1016/j.bbr.2008.09.038] [Citation(s) in RCA: 377] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 09/22/2008] [Indexed: 10/21/2022]
Abstract
In recent years the ventral pallidum has become a focus of great research interest as a mechanism of reward and incentive motivation. As a major output for limbic signals, the ventral pallidum was once associated primarily with motor functions rather than regarded as a reward structure in its own right. However, ample evidence now suggests that ventral pallidum function is a major mechanism of reward in the brain. We review data indicating that (1) an intact ventral pallidum is necessary for normal reward and motivation, (2) stimulated activation of ventral pallidum is sufficient to cause reward and motivation enhancements, and (3) activation patterns in ventral pallidum neurons specifically encode reward and motivation signals via phasic bursts of excitation to incentive and hedonic stimuli. We conclude that the ventral pallidum may serve as an important 'limbic final common pathway' for mesocorticolimbic processing of many rewards.
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Affiliation(s)
- Kyle S Smith
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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11
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Farrar AM, Font L, Pereira M, Mingote S, Bunce JG, Chrobak JJ, Salamone JD. Forebrain circuitry involved in effort-related choice: Injections of the GABAA agonist muscimol into ventral pallidum alter response allocation in food-seeking behavior. Neuroscience 2008; 152:321-30. [PMID: 18272291 DOI: 10.1016/j.neuroscience.2007.12.034] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 12/20/2007] [Accepted: 12/27/2007] [Indexed: 11/19/2022]
Abstract
Organisms often make effort-related choices based upon assessments of motivational value and work requirements. Nucleus accumbens dopamine is a critical component of the brain circuitry regulating work output in reinforcement-seeking behavior. Rats with accumbens dopamine depletions reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and instead they select a less-effortful type of food-seeking behavior. The ventral pallidum is a brain area that receives substantial GABAergic input from nucleus accumbens. It was hypothesized that stimulation of GABA(A) receptors in the ventral pallidum would result in behavioral effects that resemble those produced by interference with accumbens dopamine transmission. The present studies employed a concurrent choice lever pressing/chow intake procedure; with this task, interference with accumbens dopamine transmission shifts choice behavior such that lever pressing for food is decreased but chow intake is increased. In the present experiments, infusions of the GABA(A) agonist muscimol (5.0-10.0 ng) into the ventral pallidum decreased lever pressing for preferred food, but increased consumption of the less preferred chow. In contrast, ventral pallidal infusions of muscimol (10.0 ng) had no significant effect on preference for the palatable food in free-feeding choice tests. Furthermore, injections of muscimol into a control site dorsal to the ventral pallidum produced no significant effects on lever pressing and chow intake. These data indicate that stimulation of GABA receptors in ventral pallidum produces behavioral effects similar to those produced by accumbens dopamine depletions. Ventral pallidum appears to be a component of the brain circuitry regulating response allocation and effort-related choice behavior, and may act to convey information from nucleus accumbens to other parts of this circuitry. This research may have implications for understanding the brain mechanisms involved in energy-related psychiatric dysfunctions such as psychomotor retardation in depression, anergia, and apathy.
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Affiliation(s)
- A M Farrar
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
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12
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Zhang Y, Bailey KR, Toupin MM, Mair RG. Involvement of ventral pallidum in prefrontal cortex-dependent aspects of spatial working memory. Behav Neurosci 2005; 119:399-409. [PMID: 15839786 DOI: 10.1037/0735-7044.119.2.399] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ventral pallidum (VP) is an important source of limbic input to medial thalamus. Three studies examined the role of VP in spatial memory tasks impaired by medial thalamic lesions. In the 1st study, rats with VP lesions were impaired performing delayed matching trained with retractable levers (DMRL), a measure sensitive to prefrontal (but not hippocampal) damage. The 2nd study demonstrated dose-dependent DMRL impairment following microinjection of gamma-aminobutyric acidA, glutamate, or mu-opioid agonists in VP. In the 3rd study, VP lesions had no effect on varying choice radial-maze delayed nonmatching, a measure sensitive to hippocampal (but not prefrontal) lesions. These results suggest a common role in spatial memory for VP and other components of prefrontal-ventral striatopallidothalamic circuits distinct from hippocampal function.
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Affiliation(s)
- Yueping Zhang
- Department of Psychology, University of New Hampshire, Durham, NH 03824, USA
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13
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Bailey KR, Mair RG. Lesions of Specific and Nonspecific Thalamic Nuclei Affect Prefrontal Cortex-Dependent Aspects of Spatial Working Memory. Behav Neurosci 2005; 119:410-9. [PMID: 15839787 DOI: 10.1037/0735-7044.119.2.410] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Three studies compared lesions of specific mediodorsal (MD) and nonspecific midline/intralaminar (M/IL) and ventromedial (VM) thalamic nuclei placed to spare the anterior nuclei. Lesions of MD, M/IL, or VM impaired delayed matching trained with retractable levers, a measure of spatial memory affected by prefrontal cortical lesions. The effects of the MD lesion increased at longer retention intervals and thus appeared delay dependent. The effects of M/IL and VM lesions were delay independent. Even when combined, these lesions had no effect on varying choice radial maze delayed nonmatching, a task sensitive to hippocampal or anterior thalamic (but not prefrontal) lesions. These results demonstrate effects of MD, M/IL, and VM lesions distinct from the contributions of hippocampus or anterior thalamus to spatial memory.
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Affiliation(s)
- Kathleen R Bailey
- Department of Psychology, University of New Hampshire, Durham, NH 03824, USA
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14
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Keating GL, Winn P. Examination of the role of the pedunculopontine tegmental nucleus in radial maze tasks with or without a delay. Neuroscience 2002; 112:687-96. [PMID: 12074910 DOI: 10.1016/s0306-4522(02)00108-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Two radial maze tasks, random foraging and delayed spatial win-shift, have been used to investigate, in rats, the functions and inter-relationships of structures connected through the corticostriatal loops, such as the prelimbic cortex, nucleus accumbens, ventral pallidum and mediodorsal thalamus. The random foraging task is designed to investigate animals' ability to use spatial information to guide foraging on-line. The delayed spatial win-shift task requires, in addition, that animals hold spatially relevant information in working memory across a delay period. The pedunculopontine tegmental nucleus receives direct output from ventral striatal systems and might therefore be expected to share functional properties with them. In the present experiments we have examined the performance of rats bearing bilateral excitotoxic lesions of the pedunculopontine tegmental nucleus on both of these tasks. In acquisition tests rats were given bilateral lesions before any training took place, while in retention tests appropriate training to predetermined criterion levels of performance took place before lesions were made. In both tasks, and in both acquisition (no prelesion training) and retention (prelesion training) tests, rats with pedunculopontine lesions made significantly more errors in selecting arms to enter than did control rats. There was no motor impairment present in pedunculopontine tegmental nucleus-lesioned rats - on the contrary, on measures of speed (latency to make first arm choice and the mean time for subsequent choices) pedunculopontine-lesioned rats were slightly faster than control rats. We suggest that the pedunculopontine tegmental nucleus shares functional properties with frontostriatal systems and that it forms part of a brainstem-directed stream of striatal outflow different to the cortical re-entrant system via the thalamus.
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Affiliation(s)
- G L Keating
- School of Psychology, University of St Andrews, St Andrews, Fife, UK
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15
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A double dissociation within striatum between serial reaction time and radial maze delayed nonmatching performance in rats. J Neurosci 2002. [PMID: 12151555 DOI: 10.1523/jneurosci.22-15-06756.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Lesions involving the intralaminar thalamic nuclei have been associated with impairments in working memory and intentional motor function in human clinical cases and animal models of amnesia. The intralaminar nuclei have afferent and efferent connections related to striatum. To test whether disruption of striatal function can account for impairments produced by intralaminar lesions, we investigated the effects of striatal lesions on two tasks known to be impaired by intralaminar damage in the rat: radial maze delayed nonmatching (DNM), a measure of spatial working memory, and self-paced serial reaction time (SRT), a measure of intentional response speed. We compared the effects of lesions in four sites: the medial and lateral caudate putamen, nucleus accumbens, and olfactory tubercle. We found that lesions of the medial, accumbens, or tubercle sites impaired DNM performance, and that lesions of the lateral caudate putamen increased choice response time for the SRT task. There was a double dissociation between the effects of the ventral and the lateral lesions on these two tasks. For both tasks, the effects of striatal lesions were qualitatively similar and at least as large as intralaminar lesions in previous studies. These results provide evidence that striatal dysfunction can account for the DNM and SRT impairments produced by intralaminar lesions. The dissociation of functional impairments suggests that lateral sensorimotor areas of caudate putamen are important for responding based on external sensory stimuli and limbic-related areas in ventral striatum are important for responding based on information held in working memory.
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Kalivas PW, Jackson D, Romanidies A, Wyndham L, Duffy P. Involvement of pallidothalamic circuitry in working memory. Neuroscience 2001; 104:129-36. [PMID: 11311537 DOI: 10.1016/s0306-4522(01)00054-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study evaluated the capacity of mu-opioid and glutamate receptor agonists to differentially regulate the involvement of the GABAergic projection from the ventral pallidum to the mediodorsal thalamus in working memory and locomotor activity. Microinjection of either the ionotropic glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) or the mu agonist [D-Ala(2),N-Me-Phe(4),Gly-ol(5)]enkephalin into the ventral pallidum of male Sprague-Dawley rats produced a dose-dependent impairment in working memory, estimated using a forced delayed alternation task in a T-maze. Performance in a spatial discrimination task without delay was also impaired by glutamate, but not by mu receptor, stimulation. Involvement of the GABAergic projection from the ventral pallidum to the mediodorsal thalamus in mu-opioid-induced impairment of working memory was verified by showing that inhibiting GABA(B) receptors in the mediodorsal thalamus blocked the effect of [D-Ala(2),N-Me-Phe(4),Gly-ol(5)]enkephalin in the ventral pallidum. Similarly, either glutamate or mu-opioid receptor stimulation in the ventral pallidum elicited motor activity, and the motor stimulant effect of the mu agonist was blocked, while that of AMPA is not affected by GABA(B) receptor blockade in the mediodorsal thalamus. Distinction between mu and glutamate receptor stimulation was further revealed by the fact that stimulating mu receptors in the ventral pallidum caused a dose-dependent reduction in extracellular GABA levels, while AMPA was without effect on GABA in the ventral pallidum. These data indicate that stimulating mu-opioid receptors reduces GABAergic tone in the ventral pallidum, which increases activity in the GABAergic projection to the mediodorsal thalamus, thereby impairing working memory. Moreover, it is hypothesized that mu receptors in the ventral pallidum gate the recruitment of working memory into ongoing behavioral activity.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Baclofen/analogs & derivatives
- Baclofen/pharmacology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Excitatory Amino Acid Agonists/pharmacology
- Extracellular Space/drug effects
- Extracellular Space/physiology
- GABA Antagonists/pharmacology
- GABA-B Receptor Antagonists
- Globus Pallidus/cytology
- Globus Pallidus/drug effects
- Globus Pallidus/metabolism
- Male
- Maze Learning/drug effects
- Maze Learning/physiology
- Mediodorsal Thalamic Nucleus/cytology
- Mediodorsal Thalamic Nucleus/drug effects
- Mediodorsal Thalamic Nucleus/metabolism
- Memory, Short-Term/drug effects
- Memory, Short-Term/physiology
- Motor Activity/drug effects
- Motor Activity/physiology
- Neural Inhibition/drug effects
- Neural Inhibition/physiology
- Neural Pathways/cytology
- Neural Pathways/drug effects
- Neural Pathways/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/agonists
- Receptors, AMPA/metabolism
- Receptors, GABA-B/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- P W Kalivas
- Department of Physiology and Neuroscience, Medical University of South Carolina, Charleston, SC 29464, USA.
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Thalamic-cortical-striatal circuitry subserves working memory during delayed responding on a radial arm maze. J Neurosci 2000. [PMID: 10594086 DOI: 10.1523/jneurosci.19-24-11061.1999] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The medial dorsal nuclei of the thalamus (MDNt), the prefrontal cortex, and the ventral striatum form an interconnected neural circuit that may subserve certain types of working memory. The present series of experiments investigated functional interactions between these brain regions in rats during the performance of delayed and nondelayed spatially cued radial-arm maze tasks. In Experiment 1, transient inactivation of the MDNt by a bilateral injection of lidocaine selectively disrupted performance on a delayed task but not on a nondelayed random foraging version of the radial arm maze task. In Experiment 2, asymmetrical lidocaine injections into the MDNt on one side of the brain and the prefrontal cortex on the other transiently disconnected these two brain regions and significantly impaired foraging during the delayed task. Similarly, disconnections between the prefrontal cortex and the nucleus accumbens also disrupted foraging on this task, whereas disconnections between the MDNt and the nucleus accumbens had no effect. These data suggest that serial transmission of information among the MDNt, the prefrontal cortex, and the nucleus accumbens is required when trial-unique, short-term spatial memory is used to guide prospective search behavior. The results are discussed with respect to a distributed neural network linking limbic, thalamic, cortical, and striatal regions, which mediates executive functions of working memory.
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