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Killeen PR. Theory of reinforcement schedules. J Exp Anal Behav 2023; 120:289-319. [PMID: 37706228 DOI: 10.1002/jeab.880] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 08/04/2023] [Indexed: 09/15/2023]
Abstract
The three principles of reinforcement are (1) events such as incentives and reinforcers increase the activity of an organism; (2) that activity is bounded by competition from other responses; and (3) animals approach incentives and their signs, guided by their temporal and physical conditions, together called the "contingencies of reinforcement." Mathematical models of each of these principles comprised mathematical principles of reinforcement (MPR; Killeen, 1994). Over the ensuing decades, MPR was extended to new experimental contexts. This article reviews the basic theory and its extensions to satiation, warm-up, extinction, sign tracking, pausing, and sequential control in progressive-ratio and multiple schedules. In the latter cases, a single equation balancing target and competing responses governs behavioral contrast and behavioral momentum. Momentum is intrinsic in the fundamental equations, as behavior unspools more slowly from highly aroused responses conditioned by higher rates of incitement than it does from responses from leaner contexts. Habits are responses that have accrued substantial behavioral momentum. Operant responses, being predictors of reinforcement, are approached by making them: The sight and feel of a paw on a lever is approached by placing paw on lever, as attempted for any sign of reinforcement. Behavior in concurrent schedules is governed by approach to momentarily richer patches (melioration). Applications of MPR in behavioral pharmacology and delay discounting are noted.
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Halberstadt AL, Sindhunata IS, Scheffers K, Flynn AD, Sharp RF, Geyer MA, Young JW. Effect of 5-HT2A and 5-HT2C receptors on temporal discrimination by mice. Neuropharmacology 2016; 107:364-375. [PMID: 27020041 DOI: 10.1016/j.neuropharm.2016.03.038] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/10/2016] [Accepted: 03/23/2016] [Indexed: 11/25/2022]
Abstract
Timing deficits are observed in patients with schizophrenia. Serotonergic hallucinogens can also alter the subjective experience of time. Characterizing the mechanism through which the serotonergic system regulates timing will increase our understanding of the linkage between serotonin (5-HT) and schizophrenia, and will provide insight into the mechanism of action of hallucinogens. We investigated whether interval timing in mice is altered by hallucinogens and other 5-HT2 receptor ligands. C57BL/6J mice were trained to perform a discrete-trials temporal discrimination task. In the discrete-trials task, mice were presented with two levers after a variable interval. Responding on lever A was reinforced if the interval was <6.5 s, and responding on lever B was reinforced if the interval was >6.5 s. A 2-parameter logistic function was fitted to the proportional choice for lever B (%B responding), yielding estimates of the indifference point (T50) and the Weber fraction (a measure of timing precision). The 5-HT2A antagonist M100907 increased T50, whereas the 5-HT2C antagonist SB-242,084 reduced T50. The results indicate that 5-HT2A and 5-HT2C receptors have countervailing effects on the speed of the internal pacemaker. The hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI; 3 mg/kg IP), a 5-HT2 agonist, flattened the response curve at long stimulus intervals and shifted it to the right, causing both T50 and the Weber fraction to increase. The effect of DOI was antagonized by M100907 (0.03 mg/kg SC) but was unaffected by SB-242,084 (0.1 mg/kg SC). Similar to DOI, the selective 5-HT2A agonist 25CN-NBOH (6 mg/kg SC) reduced %B responding at long stimulus intervals, and increased T50 and the Weber fraction. These results demonstrate that hallucinogens alter temporal perception in mice, effects that are mediated by the 5-HT2A receptor. It appears that 5-HT regulates temporal perception, suggesting that altered serotonergic signaling may contribute to the timing deficits observed in schizophrenia and other psychiatric disorders.
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Affiliation(s)
- Adam L Halberstadt
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, San Diego, CA, United States.
| | - Ivan S Sindhunata
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Kees Scheffers
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Aaron D Flynn
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Richard F Sharp
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Mark A Geyer
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, San Diego, CA, United States
| | - Jared W Young
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, San Diego, CA, United States
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Heilbronner SR, Meck WH. Dissociations between interval timing and intertemporal choice following administration of fluoxetine, cocaine, or methamphetamine. Behav Processes 2014; 101:123-34. [PMID: 24135569 PMCID: PMC4081038 DOI: 10.1016/j.beproc.2013.09.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/19/2013] [Accepted: 09/21/2013] [Indexed: 12/26/2022]
Abstract
The goal of our study was to characterize the relationship between intertemporal choice and interval timing, including determining how drugs that modulate brain serotonin and dopamine levels influence these two processes. In Experiment 1, rats were tested on a standard 40-s peak-interval procedure following administration of fluoxetine (3, 5, or 8 mg/kg) or vehicle to assess basic effects on interval timing. In Experiment 2, rats were tested in a novel behavioral paradigm intended to simultaneously examine interval timing and impulsivity. Rats performed a variant of the bi-peak procedure using 10-s and 40-s target durations with an additional "defection" lever that provided the possibility of a small, immediate reward. Timing functions remained relatively intact, and 'patience' across subjects correlated with peak times, indicating a negative relationship between 'patience' and clock speed. We next examined the effects of fluoxetine (5 mg/kg), cocaine (15 mg/kg), or methamphetamine (1 mg/kg) on task performance. Fluoxetine reduced impulsivity as measured by defection time without corresponding changes in clock speed. In contrast, cocaine and methamphetamine both increased impulsivity and clock speed. Thus, variations in timing may mediate intertemporal choice via dopaminergic inputs. However, a separate, serotonergic system can affect intertemporal choice without affecting interval timing directly. This article is part of a Special Issue entitled: Associative and Temporal Learning.
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Affiliation(s)
- Sarah R Heilbronner
- Department of Pharmacology & Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Warren H Meck
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
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Pharmacological studies of performance on the free-operant psychophysical procedure. Behav Processes 2013; 95:71-89. [PMID: 23428704 DOI: 10.1016/j.beproc.2013.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 02/10/2013] [Accepted: 02/11/2013] [Indexed: 12/30/2022]
Abstract
In the free-operant psychophysical procedure (FOPP), reinforcement is provided intermittently for responding on lever A in the first half and lever B in the second half of a trial. Temporal differentiation is measured from the psychometric function (percent responding on B, %B, versus time from trial onset, t), the index of timing being T50, the value of t at %B=50. T50 is reduced by acute treatment with 5-hydroxytryptamine (5-HT1A, 5-HT2A) and dopamine (D1-like, D2-like) receptor agonists. The effects of the agonists can be reversed by the respective antagonists of these receptors. Evidence is reviewed suggesting that the effect of endogenous 5-HT is mediated by 5-HT2A receptors and the effect of endogenous dopamine by D1-like receptors. Data are presented on the effects of lesions of the prefrontal cortex and corpus striatum on the sensitivity of performance on the FOPP to D1-like and D2-like receptor agonists. Lesions of the nucleus accumbens, but not the dorsal striatum or prefrontal cortex, attenuated the effects of a D1-like receptor agonist, 6-chloro-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzazepine [SKF-81297], but not a D2-like receptor agonist, quinpirole, on T50. The results indicate that a population of D1-like receptors in the ventral striatum may contribute to the control of timing performance on the FOPP.
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Meck WH, Cheng RK, MacDonald CJ, Gainetdinov RR, Caron MG, Çevik MÖ. Gene-dose dependent effects of methamphetamine on interval timing in dopamine-transporter knockout mice. Neuropharmacology 2012; 62:1221-9. [DOI: 10.1016/j.neuropharm.2011.01.042] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/19/2011] [Accepted: 01/24/2011] [Indexed: 10/18/2022]
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Comparison of the effects of 2,5-dimethoxy-4-iodoamphetamine and D-amphetamine on the ability of rats to discriminate the durations and intensities of light stimuli. Behav Pharmacol 2010; 21:11-20. [PMID: 19949322 DOI: 10.1097/fbp.0b013e328334707a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Rats' ability to discriminate durations is disrupted by the monoamine-releasing agent D-amphetamine and the 5-HT2 receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI). It is unknown whether this effect is specific for temporal discrimination or reflects general disruption of stimulus control. This experiment addressed this question by comparing the effects of D-amphetamine and DOI on temporal discrimination and discrimination along a nontemporal dimension, light intensity. Twelve rats responded on a schedule in which a light (intensity 22 cd/m) was presented for t seconds (2.5-47.5 s), after which levers A and B were presented. Responses on A were reinforced when t was less than 25 s, and responses on B were reinforced when t was greater than 25 s. Twelve rats responded on a similar schedule in which a light of intensity i (3.6-128.5 cd/m) was presented for 25 s. Responses on A were reinforced when i was less than 22 cd/m, and responses on B were reinforced when i was greater than 22 cd/m. Logistic functions were fitted and psychophysical parameters estimated [T50, I50 (central tendency of temporal or light-intensity discrimination); Weber fraction (relative discriminative precision)]. D-Amphetamine (0.2-0.8 mg/kg) increased the Weber fraction for temporal and light-intensity discrimination; DOI (0.625-0.25 mg/kg) increased it for temporal discrimination only. Both drugs increased T50; neither altered I50. D-Amphetamine and DOI have similar effects on temporal discrimination but different effects on light-intensity discrimination. The increase in T50 may reflect the impairment of sustained attention during prolonged stimulus presentation.
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Meck WH. Acute ethanol potentiates the clock-speed enhancing effects of nicotine on timing and temporal memory. Alcohol Clin Exp Res 2008; 31:2106-13. [PMID: 18034700 DOI: 10.1111/j.1530-0277.2007.00540.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Acute ethanol administration potentiates some of the behavioral effects of nicotine, although the extent of this effect is unknown. The present investigation assessed the ability of ethanol to potentiate nicotine's effect on the overestimation of multisecond durations as a result of an increase in the speed of an internal clock. METHODS Adult male rats were exposed to the acute effects of ethanol (0.0, 0.5, 1.5, and 3.0 g/kg; IG) which was given 10 minutes prior to the administration of nicotine (0.0, 0.3, 0.6, and 1.0 mg/kg; IP). The effects of these combined treatments on timing and temporal memory were assessed using 18- and 36-second peak-interval procedures with separate visual/spatial cues for responding. RESULTS When administered alone, ethanol had no consistent effect on peak time, but decreased peak rate, and increased peak spread as a function of dose. In contrast, nicotine alone shifted the peak times of the response distributions leftward in a proportional manner as a function of dose. When administered after pretreatment with ethanol, nicotine's effect on the horizontal placement of the peak functions was potentiated. CONCLUSIONS The observation that ethanol pretreatment potentiates the clock-speed enhancing effects of subsequently administered nicotine is discussed in terms of the role of alpha7-nicotinic acetylcholine receptors and dopamine-glutamate interactions in cortico-striatal circuits thought to subserve interval timing.
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Affiliation(s)
- Warren H Meck
- Department of Psychology and Neuroscience, Duke University, Durham, North Carolina 27708, USA.
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Impairments in timing, temporal memory, and reversal learning linked to neurotoxic regimens of methamphetamine intoxication. Brain Res 2007; 1186:255-66. [PMID: 17996849 DOI: 10.1016/j.brainres.2007.10.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 09/30/2007] [Accepted: 10/03/2007] [Indexed: 01/27/2023]
Abstract
Methamphetamine intoxication has long-term consequences on dopaminergic function and corticostriatal-mediated behaviors in humans and other animals. In order to determine the potential impact on timing and temporal memory, we examined methamphetamine dose regimens that have been linked to neurotoxicity in adult (8 months) male rats. Rats that were given repetitive, high-dose methamphetamine (3.0 mg/kg ip x 4 injections/2 h) or saline injections were trained on a 2-s vs 8-s bisection procedure using auditory and visual signal durations. Following the high-dose regimen, baseline timing performance was reestablished prior to the rats' receiving reversal training in which the spatial/temporal mapping of the anchor durations (2 s and 8 s) to response options (left or right lever) was reversed. Low-dose methamphetamine (0.5 mg/kg ip) or saline injections were subsequently used to evaluate the effectiveness of the neurotoxic doses in terms of modifying the horizontal leftward shifts associated with increases in clock speed. Overall, the results indicate that MAP intoxication leads to reduced auditory/visual differences in clock speed, deficits in reversal learning, distortions in temporal memory, and lowered dopaminergic regulation of clock speed consistent with damage to prefrontal cortex and corticostriatal circuitry.
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Cheng RK, Hakak OL, Meck WH. Habit formation and the loss of control of an internal clock: inverse relationship between the level of baseline training and the clock-speed enhancing effects of methamphetamine. Psychopharmacology (Berl) 2007; 193:351-62. [PMID: 17464501 DOI: 10.1007/s00213-007-0783-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 03/21/2007] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Drugs that modulate the effective level of dopamine (DA) in cortico-striatal circuits have been shown to alter the perception of time in the seconds-to-minutes range. How this relationship changes as a function of repeated experience with the reinforcement contingencies and the gradual adaptation of the underlying neural circuits remains unclear. MATERIALS AND METHODS The present study examined the clock-speed enhancing effects of methamphetamine (MAP 0.5 or 1.0 mg/kg, ip) in groups of rats that received different levels of baseline training (20, 60, or 120 sessions) on a 50-s peak-interval (PI) procedure before initial drug administration. RESULTS A curvilinear relationship was observed such that rats that received either minimal or intermediate levels of training (<or=60 sessions) displayed dose- x training-related horizontal leftward shifts in their timing functions, suggesting that the speed of the internal clock was increased. In contrast, rats that had received an extended level of training (>or=120 sessions) did not show this "classic" DA agonist curve-shift effect, but instead displayed a dose-dependent disruption of temporal control after MAP administration. A transition from DA-sensitive to DA-insensitive mechanisms is proposed to account for the loss of control of clock speed, as timing behaviors associated with the PI procedure gradually become learned habits through the strengthening of DA-glutamate connections.
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Affiliation(s)
- Ruey-Kuang Cheng
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
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Asgari K, Body S, Bak VK, Zhang ZQ, Rickard JF, Glennon JC, Fone KCF, Bradshaw CM, Szabadi E. Effects of 5-HT2A receptor stimulation on the discrimination of durations by rats. Behav Pharmacol 2006; 17:51-9. [PMID: 16377963 DOI: 10.1097/01.fbp.0000189810.69425.89] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We recently found that rats' ability to discriminate durations of exteroceptive stimuli is disrupted by the non-selective 5-HT receptor agonist quipazine. Ketanserin reversed this effect, suggesting that the effect may be mediated by 5-HT2A receptors. Here, we report that the 5-HT2A/2C receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) also disrupts temporal discrimination, and that this effect can be reversed by ketanserin and the highly selective 5-HT2A receptor antagonist (+/-)2,3-dimethoxyphenyl-1-[2-(4-piperidine)-methanol] (MDL-100907). Twenty rats were trained to discriminate durations in a discrete-trials psychophysical procedure. In each 50-s trial, a light was presented for t seconds, following which two levers (A and B) were presented. A response on A was reinforced if t < 25 s, and a response on B if t > 25 s. Logistic psychometric curves were fitted to the proportional choice of B (%B) for derivation of timing indices [T50: time corresponding to %B = 50; Weber fraction: (T75-T25)/2T50, where T75 and T25 are times corresponding to %B = 75 and 25, respectively]. DOI 0.25 mg kg (subcutaneous) significantly increased the Weber fraction and tended to increase T50. Ketanserin 2 mg kg (subcutaneous) did not alter either parameter, but completely antagonized the effects of DOI. Similarly, MDL-100907 0.5 and 1 mg kg (intraperitoneal) did not affect performance, but completely antagonized the effects of DOI. The results indicate that the mixed 5-HT2A/2C receptor agonist DOI disrupts temporal discrimination via stimulation of 5-HT2A receptors.
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Affiliation(s)
- Karim Asgari
- Psychopharmacology Section, Division of Psychiatry bSchool of Biomedical Sciences, University of Nottingham, UK
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Asgari K, Body S, Zhang Z, Fone KCF, Bradshaw CM, Szabadi E. Effects of 5-HT1A and 5-HT2A receptor stimulation on temporal differentiation performance in the fixed-interval peak procedure. Behav Processes 2006; 71:250-7. [PMID: 16098683 DOI: 10.1016/j.beproc.2005.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Revised: 06/10/2005] [Accepted: 06/30/2005] [Indexed: 11/18/2022]
Abstract
We examined the effects of the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-HT(2A/2C) receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) on performance on the fixed-interval peak procedure, and the sensitivity of these effects to 5-HT1A and 5-HT2A receptor antagonists (N-[2-(4-[2-methoxyphenyl]-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide [WAY-100635] and ketanserin). Rats were trained to press a lever for food reinforcement in 50 min sessions consisting of 32 trials in which the lever was continuously available, separated by 10 s inter-trial intervals. In 16 trials, reinforcement was delivered following the first response after 30 s had elapsed since trial onset (fixed-interval 30 s). In 16 randomly interposed (peak/probe) trials, reinforcement was omitted, and the lever remained in the operant chamber for 120 s. Response rate in probe trials was plotted against time from trial onset. Time to peak response rate (t(peak)) and the Weber fraction were derived from modified Gaussian curves fitted to each rat's data. 8-OH-DPAT (0.05 mg kg(-1)) reduced t(peak) and increased the Weber fraction; the effect on t(peak) was antagonized by WAY-100635 (0.1 mg kg(-1)). DOI (0.25 mg kg(-1)) also reduced t(peak) and increased the Weber fraction; the reduction of t(peak) was antagonized by ketanserin (2 mg kg(-1)). Stimulation of 5-HT1A and 5-HT2A receptors alters temporal differentiation in qualitatively similar ways.
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Affiliation(s)
- K Asgari
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
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Body S, Asgari K, Cheung THC, Bezzina G, Fone KFC, Glennon JC, Bradshaw CM, Szabadi E. Evidence that the effect of 5-HT2 receptor stimulation on temporal differentiation is not mediated by receptors in the dorsal striatum. Behav Processes 2005; 71:258-67. [PMID: 16326032 DOI: 10.1016/j.beproc.2005.10.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Indexed: 11/29/2022]
Abstract
5-HT2 receptor stimulation alters temporal differentiation in free-operant timing schedules. The anatomical location of the receptor population responsible for this effect is unknown. We examined the effect of a 5-HT2 receptor agonist and antagonists, injected systemically and into the dorsal striatum, a region that is believed to play a major role in interval timing. Rats were trained under the free-operant psychophysical procedure to press levers A and B in 50s trials in which reinforcement was provided intermittently for responding on A in the first half, and B in the second half of the trial. Percent responding on B (%B) was recorded in successive 5s epochs of the trials; logistic functions were fitted to the data from each rat to derive timing indices (T50: time corresponding to %B = 50; Weber fraction: [T75-T25]/2T50, where T75 and T25 are the times corresponding to %B = 75 and %B = 25). Systemic treatment with the 5-HT(2A/2C) receptor agonist 2,5,-dimethoxy-4-iodo-amphetamine (DOI) (0.25 mg/kg, s.c.) reduced T50; the 5-HT2A receptor antagonist MDL-100907 (0.5 mg/kg, i.p.) did not affect performance, but completely blocked the effect of DOI. DOI (1 and 3 microg) injected bilaterally into the dorsal striatum did not alter T50. The effect of systemic treatment with DOI (0.25 mg/kg, s.c.) was not altered by intra-striatal injection of MDL-100907 (0.3 microg) or the 5-HT2C receptor antagonist RS-102221 (0.15 microg). The ability of systemically administered MDL-100907 to reverse DOI's effect on T50 confirms the sensitivity of temporal differentiation to 5-HT2A receptor stimulation. The failure of intra-striatal MDL-100907 to antagonize the effects of DOI suggests that 5-HT2A receptors in the dorsal striatum are unlikely to be primarily responsible for DOI's effects on timing. Furthermore, the results provide no evidence for a role of striatal 5-HT2C receptors in DOI's effect on timing.
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Affiliation(s)
- S Body
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
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