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Bastos-Gonçalves R, Coimbra B, Rodrigues AJ. The mesopontine tegmentum in reward and aversion: From cellular heterogeneity to behaviour. Neurosci Biobehav Rev 2024; 162:105702. [PMID: 38718986 DOI: 10.1016/j.neubiorev.2024.105702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/06/2024] [Accepted: 05/01/2024] [Indexed: 05/18/2024]
Abstract
The mesopontine tegmentum, comprising the pedunculopontine tegmentum (PPN) and the laterodorsal tegmentum (LDT), is intricately connected to various regions of the basal ganglia, motor systems, and limbic systems. The PPN and LDT can regulate the activity of different brain regions of these target systems, and in this way are in a privileged position to modulate motivated behaviours. Despite recent findings, the PPN and LDT have been largely overlooked in discussions about the neural circuits associated with reward and aversion. This review aims to provide a timely and comprehensive resource on past and current research, highlighting the PPN and LDT's connectivity and influence on basal ganglia and limbic, and motor systems. Seminal studies, including lesion, pharmacological, and optogenetic/chemogenetic approaches, demonstrate their critical roles in modulating reward/aversive behaviours. The review emphasizes the need for further investigation into the associated cellular mechanisms, in order to clarify their role in behaviour and contribution for different neuropsychiatric disorders.
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Affiliation(s)
- Ricardo Bastos-Gonçalves
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Bárbara Coimbra
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| | - Ana João Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal.
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2
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Vitale F, Capozzo A, Mazzone P, Scarnati E. Neurophysiology of the pedunculopontine tegmental nucleus. Neurobiol Dis 2019. [DOI: 10.1016/j.nbd.2018.03.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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3
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Wasserman DI, Wang HG, Rashid AJ, Josselyn SA, Yeomans JS. Cholinergic control of morphine-induced locomotion in rostromedial tegmental nucleus versus ventral tegmental area sites. Eur J Neurosci 2013; 38:2774-85. [DOI: 10.1111/ejn.12279] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/12/2013] [Accepted: 05/14/2013] [Indexed: 01/01/2023]
Affiliation(s)
- David I. Wasserman
- Department of Psychology; University of Toronto; 100 St. George Street; Toronto; ON; M5S 3G3; Canada
| | - Haoran G. Wang
- Department of Psychology; University of Toronto; 100 St. George Street; Toronto; ON; M5S 3G3; Canada
| | - Asim J. Rashid
- Sick Children's Research Institute; University of Toronto; 555 University Avenue; Toronto; ON; M5G 1X8; Canada
| | - Sheena A. Josselyn
- Sick Children's Research Institute; University of Toronto; 555 University Avenue; Toronto; ON; M5G 1X8; Canada
| | - John S. Yeomans
- Department of Psychology; University of Toronto; 100 St. George Street; Toronto; ON; M5S 3G3; Canada
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Simon MJ, Garcia R, Puerto A. Concurrent stimulation-induced place preference in lateral hypothalamus and parabrachial complex: Differential effects of naloxone. Behav Brain Res 2011; 225:311-6. [DOI: 10.1016/j.bbr.2011.07.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/12/2011] [Accepted: 07/17/2011] [Indexed: 12/01/2022]
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5
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Sturgess JE, Ting-A-Kee RA, Podbielski D, Sellings LHL, Chen JF, van der Kooy D. Adenosine A1 and A2A receptors are not upstream of caffeine's dopamine D2 receptor-dependent aversive effects and dopamine-independent rewarding effects. Eur J Neurosci 2010; 32:143-54. [PMID: 20576036 DOI: 10.1111/j.1460-9568.2010.07247.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Caffeine is widely consumed throughout the world, but little is known about the mechanisms underlying its rewarding and aversive properties. We show that pharmacological antagonism of dopamine not only blocks conditioned place aversion to caffeine, but also reveals dopamine blockade-induced conditioned place preferences. These aversive effects are mediated by the dopamine D(2) receptor, as knockout mice showed conditioned place preferences in response to doses of caffeine that C57Bl/6 mice found aversive. Furthermore, these aversive responses appear to be centrally mediated, as a quaternary analog of caffeine failed to produce conditioned place aversion. Although the adenosine A(2A) receptor is important for caffeine's physiological effects, this receptor seems only to modulate the appetitive and aversive effects of caffeine. A(2A) receptor knockout mice showed stronger dopamine-dependent aversive responses to caffeine than did C57Bl/6 mice, which partially obscured the dopamine-independent and A(2A) receptor-independent preferences. Additionally, the A(1) receptor, alone or in combination with the A(2A) receptor, does not seem to be important for caffeine's rewarding or aversive effects. Finally, excitotoxic lesions of the tegmental pedunculopontine nucleus revealed that this brain region is not involved in dopamine blockade-induced caffeine reward. These data provide surprising new information on the mechanism of action of caffeine, indicating that adenosine receptors do not mediate caffeine's appetitive and aversive effects. We show that caffeine has an atypical reward mechanism, independent of the dopaminergic system and the tegmental pedunculopontine nucleus, and provide additional evidence in support of a role for the dopaminergic system in aversive learning.
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Affiliation(s)
- Jessica E Sturgess
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
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Simon MJ, Molina F, Puerto A. Conditioned place preference but not rewarding self-stimulation after electrical activation of the external lateral parabrachial nucleus. Behav Brain Res 2009; 205:443-9. [DOI: 10.1016/j.bbr.2009.07.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Revised: 07/21/2009] [Accepted: 07/26/2009] [Indexed: 11/27/2022]
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Carbachol injections into the intergeniculate leaflet induce nonphotic phase shifts. Brain Res 2007; 1177:59-65. [DOI: 10.1016/j.brainres.2007.07.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 07/12/2007] [Accepted: 07/31/2007] [Indexed: 12/29/2022]
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Rada P, Hernandez L, Hoebel BG. Feeding and systemic D-amphetamine increase extracellular acetylcholine in the medial thalamus: a possible reward enabling function. Neurosci Lett 2007; 416:184-7. [PMID: 17337121 DOI: 10.1016/j.neulet.2007.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 12/13/2006] [Accepted: 02/02/2007] [Indexed: 12/19/2022]
Abstract
Acetylcholine neurons that project forward from the midbrain are known to enable dopaminergic reward functions in the ventral tegmental area. The question is whether acetylcholine might also be released in the mediodorsal thalamus for the same general purposes. Rats with a microdialysis probe lodged in the mediodorsal thalamus were allowed to eat chow for 20 min after 16-h food deprivation or were given varying doses of D-amphetamine when fed ad libitum. The result in both cases was a significant increase in extracellular acetylcholine. During feeding, acetylcholine increased to 177% of baseline. In response to d-amphetamine (2.5 mg/kg), acetylcholine increased to 184%, and with a higher dose (5 mg/kg) to 400% of baseline. It is concluded that midbrain projections to limbic portions of the thalamus provide acetylcholine for behavioral activation. This cholinergic function theoretically plays a role in enabling the limbic circuits that pass through the thalamus for reinforcement of feeding and psychostimulant abuse.
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Affiliation(s)
- P Rada
- Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida 5101, Venezuela.
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Winn P. How best to consider the structure and function of the pedunculopontine tegmental nucleus: Evidence from animal studies. J Neurol Sci 2006; 248:234-50. [PMID: 16765383 DOI: 10.1016/j.jns.2006.05.036] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This review presents the hypothesis that the best way to consider the pedunculopontine tegmental nucleus is by analogy with the substantia nigra. The substantia nigra contains two main compartments: the pars compacta and the pars reticulata. The former contains dopamine neurons that project widely within the basal ganglia while the latter is in receipt of corticostriatal output. Similarly, the PPTg contains the Ch5 acetylcholine containing neurons that project to the thalamus and corticostriatal systems (notably the pars compacta of substantia nigra and the subthalamic nucleus) while the non-cholinergic neurons of the pedunculopontine are in receipt of corticostriatal output. Assessment of the location, composition and connections of the pedunculopontine tegmental nucleus is made to support the hypothesis that it has structural similarities with substantia nigra. Assessment of the motor, sensory and cognitive functions of the pedunculopontine is also made, suggesting functional similarities exist also. Having a clear model of pedunculopontine structure and function is a matter of some importance. It is clearly involved in Parkinson's disease and could potentially be a target for therapeutic intervention. If this is to be realized it will be best to have as clear an understanding as possible of pedunculopontine structure and function in order to maximize positive benefits.
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Affiliation(s)
- Philip Winn
- School of Psychology, University of St Andrews, St Mary's Quad, South Street, St Andrews, Fife KY16 9JP, United Kingdom.
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Sharf R, McKelvey J, Ranaldi R. Blockade of muscarinic acetylcholine receptors in the ventral tegmental area prevents acquisition of food-rewarded operant responding in rats. Psychopharmacology (Berl) 2006; 186:113-21. [PMID: 16525855 DOI: 10.1007/s00213-006-0352-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Accepted: 02/10/2006] [Indexed: 11/30/2022]
Abstract
RATIONALE We recently found that muscarinic receptor (mAChR) stimulation in the ventral tegmental area (VTA) is involved in the acquisition of a feeding task. OBJECTIVE To investigate the involvement of VTA mAChR and nicotinic receptors (nAChR) in the acquisition and performance of a food-rewarded lever-pressing task. METHODS In experiment 1 (N=54), rats were trained under a fixed ratio 1 schedule of reinforcement and received bilateral intra-VTA microinjections of scopolamine (0, 2.5 or 5 microg/0.5 microl) or mecamylamine (0, 5 or 10 microg/0.5 microl) before each of the first four sessions. Before session 10, all rats that initially received a dose of either compound now received the vehicle and vice versa. In experiment 2 (N=14), rats were tested with scopolamine or mecamylamine while lever pressing under a progressive ratio schedule of reinforcement. RESULTS In experiment 1, lever pressing by rats initially treated with any mecamylamine dose or the scopolamine vehicle rose to and stayed at maximal levels for the remaining sessions. Responding by rats initially treated with the 2.5- or 5-microg dose of scopolamine remained low, even after the cessation of scopolamine treatment, and gradually rose to maximal levels by the final sessions. Injections of scopolamine 1 to 2 mm dorsal to the VTA had no significant effect on responding. In experiment 2, neither of the compounds significantly affected break points. CONCLUSIONS Stimulation of VTA mAChR, but not of nAChR, is necessary for the acquisition of a food-rewarded lever-pressing task and neither is necessary for the performance of the task.
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Affiliation(s)
- Ruth Sharf
- Department of Psychology, Queens College, CUNY, 65-30 Kissena Blvd, Flushing, NY 11367, USA.
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11
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Waraczynski MA. The central extended amygdala network as a proposed circuit underlying reward valuation. Neurosci Biobehav Rev 2006; 30:472-96. [PMID: 16243397 DOI: 10.1016/j.neubiorev.2005.09.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Accepted: 09/02/2005] [Indexed: 11/18/2022]
Abstract
The phenomenon of medial forebrain bundle self-stimulation offers a powerful model of reward-based behavior. In particular, it appears to activate a neural system whose natural function is to compute the survival value or utility of present stimuli and to help orchestrate responses toward those inputs. Although the anatomical identity of this system is as yet unknown, recent descriptions of anatomical macrosystems within the basal forebrain lead to the proposal that it may be largely contained within the central extended amygdala network. This paper reviews decades' worth of behavioral and neurophysiological investigations of brain stimulation reward that support or are at least consistent with this idea. The proposed network circuitry underlying self-stimulation is also placed into the larger context of basal forebrain function, specifically, the role of the ventral striatopallidum in linking motivation to behavior, the role of the amygdala in detecting motivationally significant inputs, and the role of the magnocellular complex in communicating reward information to cortical and hippocampal targets.
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Affiliation(s)
- Meg A Waraczynski
- Department of Psychology, University of Wisconsin-Whitewater, Whitewater, WI 53190, USA.
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Diederich K, Koch M. Role of the pedunculopontine tegmental nucleus in sensorimotor gating and reward-related behavior in rats. Psychopharmacology (Berl) 2005; 179:402-8. [PMID: 15821954 DOI: 10.1007/s00213-004-2052-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 09/24/2004] [Indexed: 12/24/2022]
Abstract
RATIONALE The pedunculopontine tegmental nucleus (PPTg) is involved in the execution and regulation of a variety of behaviors. Most investigations used brain lesions that have certain disadvantages, such as functional compensation over time. OBJECTIVES In the present study, we investigated by temporary, reversible inhibition of neurons the role of the PPTg in sensorimotor gating, measured as prepulse inhibition (PPI) of the acoustic startle response (ASR) using variable interstimulus intervals (ISI). In a second set of experiments we examined by the same technique the role of the PPTg in a progressive-ratio instrumental response task. METHODS Local infusions of the GABA(A)-receptor agonist muscimol (0.05 microg and 0.5 microg/0.3 microl, or vehicle) were applied through indwelling microinfusion cannulae into the PPTg of freely moving rats. ASR and PPI were measured using acoustic stimuli of 100 dB (pulse) and 80 dB (prepulse) using ISIs of 25, 120, 520 and 1,020 ms. Instrumental behavior (lever pressing for casein pellets) was assessed in a Skinner box. Motor activity was measured in an open field. RESULTS Intra-PPTg infusions of muscimol dose-dependently attenuated PPI at ISIs of 120 ms and 520 ms, but not at longer or shorter ISIs. ASR magnitude in pulse-alone trials was not significantly affected. Intra-PPTg infusion of 0.5 microg muscimol reduced the break point of instrumental responding (testing sequence where the rats fail to respond according to an increased ratio of reinforcement). No effects on food-preference and open-field activity were found. CONCLUSIONS These findings suggest that GABAergic neurotransmission in the PPTg plays an important role for sensorimotor gating at intermediate ISIs and for response selection under demanding schedules of reinforcement.
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Affiliation(s)
- Kai Diederich
- Department of Neuropharmacology, Brain Research Institute, University of Bremen, FB 2, PO Box 33 04 40, 28334 Bremen, Germany.
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13
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Champtiaux N, Changeux JP. Knockout and knockin mice to investigate the role of nicotinic receptors in the central nervous system. PROGRESS IN BRAIN RESEARCH 2004; 145:235-51. [PMID: 14650919 DOI: 10.1016/s0079-6123(03)45016-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The recent use of genetically engineered knockout (Ko) and knockin (Kin) animals for neurotransmitter receptor genes, in particular, nicotinic acetylcholine receptors (nAChRs) in the brain, has provided a powerful alternative to the classical pharmacological approach. These animal models are not only useful in order to reexamine and refine the results derived from pharmacological studies, but they do also provide a unique opportunity to determine the subunit composition of the nicotinic receptors which modulate various brain functions. Ultimately, this knowledge will be valuable in the process of designing new drugs that will mimic the effects of nicotine on several important pathologies or on smoking cessation therapies. In this review, we present recent data obtained from the studies of mutant animals that contributed to our understanding of the role and composition of nAChRs in the central nervous system (CNS). The advantages and pitfalls of Ko animal models will also be discussed.
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Affiliation(s)
- Nicolas Champtiaux
- Laboratoire de Neurobiologie Moléculaire, Centre National de la Recherche scientifique, Unité de Recherche Associée 2182 Récepteurs et Cognition, Institut Pasteur, 75724 Paris, France
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Ivlieva NY, Timofeeva NO. Neuron activity in the pedunculopontine nucleus during an operant conditioned defensive reflex. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2003; 33:499-506. [PMID: 12921181 DOI: 10.1023/a:1023419418869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The activity of 109 neurons in the compact and diffuse zones of the pedunculopontine nucleus was studied in freely mobile rabbits during the acquisition and performance of a defensive operant conditioned reflex. A total of 47% of the neurons recorded showed responsive properties to the conditioned stimulus, which is evidence for the involvement of the pedunculopontine nucleus in operant learning. A significant predominance of excitatory conditioned reflex responses to the conditioned stimulus was demonstrated, showing that the nature of the influence of the pedunculopontine nucleus on projection structures during learning is mostly excitatory. The main patterns of cell responses to the conditioned stimulus were identified, these reflecting the nature of the influence of the conditioned stimulus on neuron activity, the structure of the behavioral act, and the properties of the reinforcement, suggesting a relationship between the pedunculopontine nucleus and the processes of attention, motor learning, and reinforcement. A significant decrease in the reactivity of neurons in the pedunculopontine nucleus to the conditioned stimulus as a result of specialization due to learning was demonstrated. Differences in the associative reactive properties of the compact and diffuse zones of the pedunculopontine nucleus to the conditioned stimulus were identified, which is evidence for the functional heterogeneity of this formation and suggests a leading role for the cholinergic compact zone in operant defensive behavior.
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Affiliation(s)
- N Yu Ivlieva
- Department of Higher Nervous Activity, M. V. Lomonosov Moscow State University
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Alderson HL, Brown VJ, Latimer MP, Brasted PJ, Robertson AH, Winn P. The effect of excitotoxic lesions of the pedunculopontine tegmental nucleus on performance of a progressive ratio schedule of reinforcement. Neuroscience 2002; 112:417-25. [PMID: 12044459 DOI: 10.1016/s0306-4522(02)00087-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The pedunculopontine tegmental nucleus has connections with sites in both dorsal and ventral striatum, and a number of studies have suggested that it has a role in reward-related behaviour. The present experiment aimed to investigate the perception of reward in pedunculopontine tegmental nucleus-lesioned rats responding for food under a progressive ratio schedule, which measures willingness to work for a given reward. Rats were trained on a progressive ratio-5 schedule for food reward, then given ibotenic acid or sham lesions of the pedunculopontine tegmental nucleus. Their performance under this schedule was examined again following recovery from surgery. Compared with sham-lesioned rats, those with lesions of the pedunculopontine tegmental nucleus showed significantly reduced breaking points and significantly longer post-reinforcement pauses. However, there was no difference between the groups in their latency to collect food pellets once earned, suggesting that pedunculopontine tegmental nucleus excitotoxin and sham-lesioned rats were equally motivated by the presence of food. Excitotoxin-lesioned rats made significantly more responses on the control lever and more entries to the food hopper as progressive ratio increment increased, but did not differ from controls when the schedule requirement was low. These results are interpreted as indicating no global loss of motivation, since lesioned rats performed normally at low schedule requirements, and were as fast as controls to collect pellets. But as the schedule requirement increased, excitotoxin-lesioned rats showed reductions in responding on the active lever (that is, a reduction in breaking point) and an increase in inappropriate responses towards the food hopper and the control lever.We consider these data to indicate that the behavioural deficits in pedunculopontine-lesioned rats arise not from a sensory or hedonic change, but from alteration in the control of motor output.
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Affiliation(s)
- H L Alderson
- School of Psychology, University of St Andrews, Fife, UK.
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16
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Keating GL, Walker SC, Winn P. An examination of the effects of bilateral excitotoxic lesions of the pedunculopontine tegmental nucleus on responding to sucrose reward. Behav Brain Res 2002; 134:217-28. [PMID: 12191808 DOI: 10.1016/s0166-4328(02)00032-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effects of bilateral excitotoxic lesions of the pedunculopontine tegmental nucleus (PPTg) on sucrose intake were examined in three experiments. First, in tests of conditioned place preference using 20% sucrose as the reinforcer, it was shown that lesioned rats, regardless of whether they were food deprived or non-deprived, formed normal place preferences and showed normal amounts of locomotion. However, consumption of 20% sucrose in the pairing trials was increased in the deprived PPTg lesioned rats compared to their matched controls. A second experiment showed that sucrose consumption in the home cage was increased in both deprived and non-deprived PPTg lesioned rats, but only when the concentration of sucrose was greater than 12%: below this there were no differences in intake between the lesioned and control rats. In a third home cage experiment, it was again shown that non-deprived PPTg lesioned rats increased their consumption of 20% sucrose compared to controls. PPTg lesioned rats concomitantly reduced their intake of lab chow such that overall energy intake remained the same as that of control rats. These data are taken to suggest (i) that bilateral excitotoxic lesions of the PPTg increase consumption of sucrose selectively in conditions of high motivational excitement; (ii) that the perception of the rewarding value of 20% sucrose, as judged by place preference, is not affected by these lesions; and (iii) that PPTg lesioned rats are able to adjust their energy intake to accommodate increased sucrose loads. These data are consistent with the hypothesis that bilateral excitotoxic lesions of the PPTg do not affect energy balance regulation or judgment of the hedonic value of sucrose, but that they do affect the control of responding in the face of high levels of motivational excitement.
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Affiliation(s)
- Glenda L Keating
- School of Psychology, University of St Andrews, St Andrews, Fife KY16 9JU, Scotland, UK
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17
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Arnold JC, Topple AN, Mallet PE, Hunt GE, McGregor IS. The distribution of cannabinoid-induced Fos expression in rat brain: differences between the Lewis and Wistar strain. Brain Res 2001; 921:240-55. [PMID: 11720732 DOI: 10.1016/s0006-8993(01)03127-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies have suggested that cannabis-like drugs produce mainly aversive and anxiogenic effects in Wistar strain rats, but rewarding effects in Lewis strain rats. In the present study we compared Fos expression, body temperature effects and behavioral effects elicited by the cannabinoid CB(1) receptor agonist CP 55,940 in Lewis and Wistar rats. Both a moderate (50 microg/kg) and a high (250 microg/kg) dose level were used. The 250 microg/kg dose caused locomotor suppression, hypothermia and catalepsy in both strains, but with a significantly greater effect in Wistar rats. The 50 microg/kg dose provoked moderate hypothermia and locomotor suppression but in Wistar rats only. CP 55,940 caused significant Fos immunoreactivity in 24 out of 33 brain regions examined. The most dense expression was seen in the paraventricular nucleus of the hypothalamus, the islands of Calleja, the lateral septum (ventral), the central nucleus of the amygdala, the bed nucleus of the stria terminalis (lateral division) and the ventrolateral periaqueductal gray. Despite having a similar distribution of CP 55,940-induced Fos expression, Lewis rats showed less overall Fos expression than Wistars in nearly every brain region counted. This held equally true for anxiety-related brain structures (e.g. central nucleus of the amygdala, periaqueductal gray and the paraventricular nucleus of the hypothalamus) and reward-related sites (nucleus accumbens and pedunculopontine tegmental nucleus). In a further experiment, Wistar rats and Lewis rats did not differ in the amount of Fos immunoreactivity produced by cocaine (15 mg/kg). These results indicate that Lewis rats are less sensitive to the behavioral, physiological and neural effects of cannabinoids. The exact mechanism underlying this subsensitivity requires further investigation.
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MESH Headings
- Analgesics/pharmacology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Body Temperature/drug effects
- Body Temperature/physiology
- Brain/drug effects
- Brain/metabolism
- Cannabinoids/pharmacology
- Catalepsy/chemically induced
- Catalepsy/metabolism
- Catalepsy/physiopathology
- Cell Count
- Cyclohexanols/pharmacology
- Dose-Response Relationship, Drug
- Immunohistochemistry
- Marijuana Abuse/metabolism
- Marijuana Abuse/physiopathology
- Motor Activity/drug effects
- Motor Activity/physiology
- Neurons/drug effects
- Neurons/metabolism
- Proto-Oncogene Proteins c-fos/metabolism
- Rats
- Rats, Inbred Lew/anatomy & histology
- Rats, Inbred Lew/metabolism
- Rats, Wistar/anatomy & histology
- Rats, Wistar/metabolism
- Receptors, Cannabinoid
- Receptors, Drug/drug effects
- Receptors, Drug/metabolism
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Affiliation(s)
- J C Arnold
- Department of Psychology, Faculty of Science, University of Sydney, Sydney, NSW 2006, Australia.
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Satorra-Marín N, Coll-Andreu M, Portell-Cortés I, Aldavert-Vera L, Morgado-Bernal I. Impairment of two-way active avoidance after pedunculopontine tegmental nucleus lesions: effects of conditioned stimulus duration. Behav Brain Res 2001; 118:1-9. [PMID: 11163628 DOI: 10.1016/s0166-4328(00)00306-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It was investigated whether the disruptive effects of bilateral lesions of the pedunculopontine tegmental nucleus on two-way active avoidance might vary depending on variations of task demand. The animals were either subjected to bilateral electrolytic lesions of the pedunculopontine tegmental nucleus (Lesion groups) or were sham-operated (Control groups). All the rats were subjected to two 30-trial sessions of two-way active avoidance (separated by ten days), using either a 10-s conditioned stimulus (low task demand) or a 3-s conditioned stimulus (high task demand). The lesions induced a significant disruption of two-way active avoidance in the two conditions tested, but, in both lesioned and control rats, the number of avoidance responses was higher when the 10-s conditioned stimulus was used. In lesioned animals, the condition of high task demand was associated with a significant increase of escape failures. Lesions did not affect locomotor activity during the period of adaptation to the conditioning apparatus, but induced training-specific motor deficits (a decrease of intertrial crossings and an enhancement of escape latencies) regardless of the specific training conditions used. The results are discussed in terms of the influences of the pedunculopontine tegmental nucleus in thalamocortical and striatal systems.
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Affiliation(s)
- N Satorra-Marín
- Departament de Psicobiologia i de Metodologia de les Ciències de la Salut, Universitat Autònoma de Barcelona, Edifici B, 08193 Bellaterra, Barcelona, Spain
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19
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Steidl S, Li L, Yeomans JS. Conditioned brain-stimulation reward attenuates the acoustic startle reflex in rats. Behav Neurosci 2001. [DOI: 10.1037/0735-7044.115.3.710] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Leri F, Franklin KB. Diazepam modifies the effect of pedunculopontine lesions on morphine but not on amphetamine conditioned place preference. Behav Brain Res 2000; 117:21-7. [PMID: 11099754 DOI: 10.1016/s0166-4328(00)00282-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have previously shown that T-maze learning impairments caused by lesions to the pedunculopontine tegmental nucleus (PPTg) can be reversed by the anxiolytic diazepam. We now report that diazepam also reverses the effect of PPTg lesions on conditioned place preference (CPP) to morphine but not to amphetamine. Rats with bilateral sham or N-methyl-D-aspartate lesions (0.1 or 0.05 M) to the PPTg were trained in a unbiased CPP paradigm with 2 mg/kg morphine or 2 mg/kg D-amphetamine associated with one compartment of the apparatus and vehicle injections in the alternative compartment. After three drug/saline-compartment pairings, the preference of the animals was assessed by allowing them to explore the entire apparatus for 20 min. In contrast to sham-lesioned subjects, the rats with PPTg lesions did not show a preference for the compartment paired with morphine or amphetamine. In two experiments the expression of a morphine CPP was restored by injecting the lesioned animals with 1 mg/kg of diazepam 30 min before the test session. Diazepam pre-treatment did not restore the expression of amphetamine CPP.
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Affiliation(s)
- F Leri
- Department of Psychology, McGill University, 1205 Dr Penfield Ave., Montreal, H3A-1B1, Quebec, Canada.
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Waraczynski M, Perkins M. Temporary inactivation of the retrorubral fields decreases the rewarding effect of medial forebrain bundle stimulation. Brain Res 2000; 885:154-65. [PMID: 11102569 DOI: 10.1016/s0006-8993(00)02908-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prior studies indicate that lesioning the retrorubral fields (RRF) decreases the rewarding effect of medial forebrain bundle (MFB) stimulation, although these studies did not make the RRF their primary target. This study directly investigates the role of the RRF in MFB self-stimulation using transient lidocaine-induced inactivation of target tissue rather than permanent lesioning. In 18 rats with MFB stimulation electrodes, inactivation of the RRF via 0. 5 and 1.0 microl of 4% lidocaine produced immediate, substantial upward shifts in the frequency required to maintain half-maximal self-stimulation response rates whereas injecting comparable volumes of saline did not. Bilateral inactivation was particularly effective, especially at medium and high stimulation currents, although unilateral inactivation ipsilateral to the stimulation site was also effective. Contralateral inactivation alone did not substantially change the stimulation's reward value, although contralateral inactivation appeared to contribute to the effectiveness of bilateral inactivation. The frequency required to maintain half-maximal responding returned to baseline levels by 15-20 min after lidocaine infusion. In seven rats whose infusion sites were not in the RRF, lidocaine inactivation did not consistently degrade the stimulation's reward value. These results indicate that some neural elements located in the RRF contribute to the rewarding effect of MFB stimulation. Possible roles for these elements in the anatomical substrate for MFB self-stimulation are discussed.
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Affiliation(s)
- M Waraczynski
- Department of Psychology, University of Wisconsin-Whitewater, 800 W. Main St., Whitewater, WI 53190, USA.
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Mediavilla C, Molina F, Puerto A. Electrolytic lesions of the pedunculopontine nucleus disrupt concurrent learned aversion induced by NaCl. Neurobiol Learn Mem 2000; 74:105-18. [PMID: 10933897 DOI: 10.1006/nlme.1999.3941] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Bilateral electrolytic lesions in the pedunculopontine nucleus (PPN) impair acquisition of short-term, or concurrent, Taste Aversion Learning (TAL) in rats. This type of TAL is characterized by the daily presentation of two different flavor stimuli at the same time, one associated with simultaneous intragastric administration of an aversive product (hypertonic NaCl) and the other with physiological saline. Sham-lesioned control animals learn this taste discrimination task, but both lesioned animals and control animals learn a long-term, or delayed, TAL task in which each gustatory stimulus is presented individually every other day and the intragastric products, LiCl (0.15 M) and physiological saline, are administered after a 15-min delay. These results are analyzed in the context of the cerebellar circuits involved in learning and in relation to the two TAL modalities described above.
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Affiliation(s)
- C Mediavilla
- Area de Psicobiología, Departamento de Psicología Experimental y Fisiología del Comportamiento, Universidad de Granada, Campus de Cartuja, Granada 18071, Spain.
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Winn P. Frontal syndrome as a consequence of lesions in the pedunculopontine tegmental nucleus: a short theoretical review. Brain Res Bull 1998; 47:551-63. [PMID: 10078613 DOI: 10.1016/s0361-9230(98)00136-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
In this review, it is argued that the consequence of bilateral damage to the pedunculopontine tegmental nucleus (PPTg) in experimental animals is the production of a form of frontal syndrome. Frontal syndrome is a term used to describe the behavioural consequences of damage to the frontal lobes in human patients. These behavioural changes can be classified as disinhibition of behaviour (a release of behavioural control), the production of inappropriate behaviour (which in patients can be either inappropriate actions or verbal behaviour), and the production of perseverative behaviour (the maintenance of an action beyond the point at which it should have been terminated). The psychological changes which underlie these behavioural changes are thought to involve executive functions, which include such things as the prospective planning of sequences of actions, attentional shifting and working memory. In this review, I attempt to demonstrate two things: first, that there are significant anatomical connections from frontostriatal systems to the PPTg. The motor cortex projects directly to the PPTg while the prefrontal cortex contacts it via striatal circuitry, forming clear routes by which the frontal lobes can communicate with the PPTg. Second, having established the existence of connections between frontostriatal systems and the PPTg, behavioural data are described. Experimental animals bearing bilateral lesions of the PPTg have been examined in a wide variety of tasks. Animals bearing such lesions are not impaired in basic processes of feeding, drinking, locomotion, or grooming and simple observation of lesioned rats' normal behaviour reveals no obvious gross impairment in function. However, the results of more subtle tests reveal a wide variety of deficits in various tasks. The outcome of these experiments are in many ways contradictory, but in the vast majority of cases, the changes can be described as involving disinhibition of behaviour, the release of inappropriate behaviour, and the production of perseverative behaviour. Anatomical and behavioural data support the conclusion that there are functional connections between frontal systems and the PPTg. This review also discusses what psychological processes might be served by such connections.
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Affiliation(s)
- P Winn
- School of Psychology, University of St. Andrews, Fife, UK.
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Leri F, Franklin KB. Learning impairments caused by lesions to the pedunculopontine tegmental nucleus: an artifact of anxiety? Brain Res 1998; 807:187-92. [PMID: 9757032 DOI: 10.1016/s0006-8993(98)00762-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Bilateral N-methyl-d-aspartate lesions of the pedunculopontine tegmental nucleus (PPTg) blocked the acquisition of a delayed non-matching to position task (DNMP) performed in a T-maze. This acquisition impairment, however, was reversed by pre-testing injections of diazepam (1 mg/kg). These results, in addition to the finding that PPTg lesions elevated anxiety as measured by the elevated plus maze, suggest that PPTg is not involved in learning or memory, but in the regulation of anxiety.
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Affiliation(s)
- F Leri
- Department of Psychology, McGill University, 1205 Dr. Penfield Ave., Montreal, Quebec H3A-1B1, Canada
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Schechter MD, Calcagnetti DJ. Continued trends in the conditioned place preference literature from 1992 to 1996, inclusive, with a cross-indexed bibliography. Neurosci Biobehav Rev 1998; 22:827-46. [PMID: 9809314 DOI: 10.1016/s0149-7634(98)00012-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In light of the overwhelming response to the previous publication in Neuroscience and Biobehavioral Reviews (1993, 17, 21-41) regarding trends in place conditioning (either preference or aversion), the present work constitutes a five-year follow-up to review the empirical research in this behavioral paradigm from 1992 to 1996, inclusively. The behavioral technique has grown as indicated by the number of publications over the last five years which equals those authored over the 35 years covered by our last survey. The previous work used descriptive statistics to explore topical issues, whereas the present work discusses trends since that time and hopes to provide an exhaustive bibliography of the CPP literature, including articles, published abstracts, book chapters and reviews, as well as providing a cross-index of identified key words/drugs tested.
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Affiliation(s)
- M D Schechter
- Department of Pharmacology, Northeastern Ohio University College of Medicine, Rootstown 44272-0095, USA.
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Waraczynski M, Perkins M. Lesions of pontomesencephalic cholinergic nuclei do not substantially disrupt the reward value of medial forebrain bundle stimulation. Brain Res 1998; 800:154-69. [PMID: 9685623 DOI: 10.1016/s0006-8993(98)00519-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study examines the effects of lesioning the pedunculopontine tegmentum (PPTg) and laterodorsal tegmentum (LDTg) on the reward effectiveness of medial forebrain bundle (MFB) stimulation. Although the focus is on the effects of unilateral lesions made ipsilateral to stimulation sites in the hypothalamic and ventral tegmental MFB, the effects of contralateral lesions of both targets are also investigated. Reward effectiveness was assessed using the rate-frequency curve shift paradigm. In nine rats with unilateral PPTg lesions and five rats with unilateral LDTg lesions, the frequency required to maintain half-maximal response rats was generally not changed by more than 0.1 log units relative to prelesion baseline mean. In three rats with contralateral PPTg lesions and four rats with contralateral LDTg lesions, required frequency was also not substantially changed. The results are interpreted in terms of a previously proposed hypothesis regarding the role in MFB self-stimulation of ascending cholinergic input from the pontomesencephalon to ventral tegmental dopaminergic neurons.
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Affiliation(s)
- M Waraczynski
- Department of Psychology, University of Wisconsin in Whitewater, Whitewater, WI 53190, USA.
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Effects of pedunculopontine tegmental nucleus lesions on responding for intravenous heroin under different schedules of reinforcement. J Neurosci 1998. [PMID: 9634569 DOI: 10.1523/jneurosci.18-13-05035.1998] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The pedunculopontine tegmental nucleus (PPTg) is believed to play important roles in reward and learning. We examined the effect of PPTg lesions (0.5 microl of 0.1 M NMDA injected bilaterally over 10 min) on the learning of an operant response for opiate reward. In 14 adult male Long-Evans rats, bilateral lesions of the PPTg disrupted the acquisition of responding for intravenous heroin (0.1 mg/kg infused at a rate of 0.25 ml/28 sec) on a fixed ratio-1 (FR-1) schedule of reinforcement. The 12 remaining lesioned animals increased their heroin intake over the acquisition sessions but did not reach the response levels of sham-lesioned animals on the 15th and final session. The sham- and PPTg-lesioned animals that learned the FR-1 task exhibited similar patterns of responding during extinction and reacquisition sessions. When tested on a progressive ratio (PR) schedule of reinforcement, however, PPTg-lesioned animals had lower break points than sham-lesioned animals. Asymmetric lesions, which destroyed the majority of the nucleus in one hemisphere only, did not produce any behavioral deficits. Rats that were lesioned after training also did not show deficits in responding under either FR or PR schedules. These findings suggest that PPTg lesions reduce the rewarding effect of opiates but do not disrupt the ability either to learn an operant response or the response requirements of a PR schedule.
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David V, Durkin TP, Cazala P. Rewarding effects elicited by the microinjection of either AMPA or NMDA glutamatergic antagonists into the ventral tegmental area revealed by an intracranial self-administration paradigm in mice. Eur J Neurosci 1998; 10:1394-402. [PMID: 9749793 DOI: 10.1046/j.1460-9568.1998.00150.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In order to study the functional role of the trans-synaptic neuronal interaction between glutamatergic afferents and mesolimbic dopaminergic neurons in internal reward processes, BALB/c male mice were unilaterally implanted with a guide-cannula, the tip of which was positioned 1.5 mm above the ventral tegmental area (VTA). On each day of the following experimental period, a stainless steel injection cannula was inserted into the VTA in order to study the eventual self-administration behaviour of either the competitive N-methyl-D-aspartate antagonist, D(-)-2-amino-7-phosphonoheptanoic acid (AP-7) or the alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid antagonist, 6,7-dinitroquinoxaline-2,3-dione (DNQX) (3 ng/50 nL) using a spatial discrimination task in a Y maze. Mice rapidly discriminated between the arm enabling a microinjection of either of these glutamatergic antagonists and the neutral arm of the maze, and a robust self-administration of either of these compounds was observed from the first session of acquisition. These data provide strong evidence that the intra-VTA microinjection of either of these subclasses of glutamatergic antagonist produces an effect which is interpreted centrally by the experimental subjects as being highly rewarding. Once the self-administration response had been fully acquired by the experimental subjects, preinjection of the dopaminergic D2 antagonist, sulpiride (50 mg/kg i.p.), 30 min before the test, produced a rapid extinction of the self-administration response. This latter result demonstrates the dopaminergic D2 receptor dependence of this intra-VTA self-administration of both of these subclasses of glutamatergic antagonist. We conclude that the different glutamatergic afferent neuronal inputs to the VTA globally exert, in vivo, via the mediation of interposed endogenous GABAergic interneurons, a tonic trans-synaptic inhibitory regulation of neuronal activity in the mesolimbic dopaminergic pathway and that this complex neuronal interaction in the VTA plays a significant functional part in the modulation of internal reward processes.
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Affiliation(s)
- V David
- Laboratoire de Neurosciences Comportementales et Cognitives, CNRS URA 339, Université de Bordeaux I, Talence, France
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Hunt GE, McGregor IS. Rewarding brain stimulation induces only sparse Fos-like immunoreactivity in dopaminergic neurons. Neuroscience 1998; 83:501-15. [PMID: 9460758 DOI: 10.1016/s0306-4522(97)00409-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this study, c-fos immunohistochemistry was used to identify the brain regions activated by rewarding brain stimulation in rats. Rats had monopolar electrodes implanted in the medial forebrain bundle and were allocated to either a self-stimulation (n = 4), yoked stimulation (n = 4) or no stimulation (n = 6) group. In a single 1 h test session, each rat in the self-stimulation group made 1000 nose poke responses with each response followed by a 0.5 s train of brain stimulation. Rats in the yoked-stimulation group were paired with a partner in the self-stimulation group and received brain stimulation whenever their partner did. However, their nose poke responses did not trigger stimulation. This yoked procedure was thus used to identify any Fos-like immunoreactivity due to operant responding. Rats in the no stimulation group were placed in the same apparatus as the other rats but received no brain stimulation and were thus used to assess baseline Fos-like immunoreactivity. Results showed that stimulation increased Fos-like immunoreactivity in many areas of the brain in both the self-stimulation and yoked groups. The areas with the highest Fos-like immunoreactivity were ipsilateral to the electrode site and included the medial prefrontal cortex, lateral septum, nucleus accumbens (shell), the medial and lateral preoptic areas, bed nucleus of the stria terminalis, central amygdala, lateral habenula, dorsomedial hypothalamus, lateral hypothalamus and the anterior ventral tegmental area. Bilateral Fos-like immunoreactivity was evident in the nucleus accumbens core, paraventricular nucleus of the hypothalamus, the retrorubral fields and the locus coeruleus. A double-labelling procedure identifying both Fos and tyrosine hydroxylase was used to show that very few (< 5%) of the A10 dopamine cell bodies in the ventral tegmental area expressed Fos following brain stimulation. In contrast, most of the noradrenergic neurons of the locus coeruleus (A6), rubrospinal tract (A5) and pontine tegmental area (A7) were Fos positive. Overall, the results show that rewarding, brain stimulation induces Fos-like immunoreactivity in many forebrain regions but only sparsely in mesolimbic and mesocortical dopamine neurons. The similar patterns of Fos-like immunoreactivity seen in the self-stimulation and yoked-stimulation groups suggests that the operant responding for brain stimulation causes minimal Fos expression in itself.
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Affiliation(s)
- G E Hunt
- Department of Psychological Medicine, University of Sydney, Concord Hospital, N.S.W., Australia
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Abstract
The allocation of behavior among competing activities and goal objects depends on the payoffs they provide. Payoff is evaluated among multiple dimensions, including intensity, rate, delay, and kind. Recent findings suggest that by triggering a stream of action potentials in myelinated, medial forebrain bundle axons, rewarding electrical brain stimulation delivers a meaningful intensity signal to the process that computes payoff.
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Affiliation(s)
- P Shizgal
- Center for Studies in Behavioral Neurobiology, Concordia University, 1455 de Maisonneuve Boulevard West, Montreal, Quebec, Canada H3G 1MB.
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