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Balcı F, Freestone D. The Peak Interval Procedure in Rodents: A Tool for Studying the Neurobiological Basis of Interval Timing and Its Alterations in Models of Human Disease. Bio Protoc 2020; 10:e3735. [PMID: 33659396 PMCID: PMC7854006 DOI: 10.21769/bioprotoc.3735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 11/02/2022] Open
Abstract
Animals keep track of time intervals in the seconds to minutes range with, on average, high accuracy but substantial trial-to-trial variability. The ability to detect the statistical signatures of such timing behavior is an indispensable feature of a good and theoretically-tractable testing procedure. A widely used interval timing procedure is the peak interval (PI) procedure, where animals learn to anticipate rewards that become available after a fixed delay. After learning, they cluster their responses around that reward-availability time. The in-depth analysis of such timed anticipatory responses leads to the understanding of an internal timing mechanism, that is, the processing dynamics and systematic biases of the brain's clock. This protocol explains in detail how the PI procedure can be implemented in rodents, from training through testing to analysis. We showcase both trial-by-trial and trial-averaged analytical methods as a window into these internal processes. This protocol has the advantages of capturing timing behavior in its full-complexity in a fashion that allows for a theoretical treatment of the data.
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Affiliation(s)
- Fuat Balcı
- Koç University, Department of Psychology, Istanbul, Turkey
| | - David Freestone
- William Paterson University, Department of Psychology, NJ, United States
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2
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Abstract
Psychedelics (serotonergic hallucinogens) are powerful psychoactive substances that alter perception and mood and affect numerous cognitive processes. They are generally considered physiologically safe and do not lead to dependence or addiction. Their origin predates written history, and they were employed by early cultures in many sociocultural and ritual contexts. After the virtually contemporaneous discovery of (5R,8R)-(+)-lysergic acid-N,N-diethylamide (LSD)-25 and the identification of serotonin in the brain, early research focused intensively on the possibility that LSD and other psychedelics had a serotonergic basis for their action. Today there is a consensus that psychedelics are agonists or partial agonists at brain serotonin 5-hydroxytryptamine 2A receptors, with particular importance on those expressed on apical dendrites of neocortical pyramidal cells in layer V. Several useful rodent models have been developed over the years to help unravel the neurochemical correlates of serotonin 5-hydroxytryptamine 2A receptor activation in the brain, and a variety of imaging techniques have been employed to identify key brain areas that are directly affected by psychedelics. Recent and exciting developments in the field have occurred in clinical research, where several double-blind placebo-controlled phase 2 studies of psilocybin-assisted psychotherapy in patients with cancer-related psychosocial distress have demonstrated unprecedented positive relief of anxiety and depression. Two small pilot studies of psilocybin-assisted psychotherapy also have shown positive benefit in treating both alcohol and nicotine addiction. Recently, blood oxygen level-dependent functional magnetic resonance imaging and magnetoencephalography have been employed for in vivo brain imaging in humans after administration of a psychedelic, and results indicate that intravenously administered psilocybin and LSD produce decreases in oscillatory power in areas of the brain's default mode network.
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Affiliation(s)
- David E Nichols
- Eschelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina
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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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Lake JI, Meck WH. Differential effects of amphetamine and haloperidol on temporal reproduction: Dopaminergic regulation of attention and clock speed. Neuropsychologia 2013; 51:284-92. [DOI: 10.1016/j.neuropsychologia.2012.09.014] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 09/03/2012] [Accepted: 09/06/2012] [Indexed: 11/26/2022]
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Valencia-Torres L, Olarte-Sánchez C, Body S, Fone K, Bradshaw C, Szabadi E. Fos expression in the orbital prefrontal cortex after exposure to the fixed-interval peak procedure. Behav Brain Res 2012; 229:372-7. [PMID: 22301352 PMCID: PMC3657145 DOI: 10.1016/j.bbr.2012.01.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 01/13/2012] [Accepted: 01/14/2012] [Indexed: 12/26/2022]
Abstract
It has been proposed that cortico-striato-thalamo-cortical circuits that incorporate the prefrontal cortex and dorsal striatum regulate interval timing behaviour. The present experiment examined whether performance on the fixed-interval peak procedure (FIPP), an immediate timing schedule, would induce neuronal activity in cortical and striatal areas, as revealed by enhanced expression of the Fos protein, a marker for neuronal activation. Regional Fos expression was compared between rats trained on the FIPP and rats trained on a variable-interval (VI) schedule matched to the FIPP for overall response rate and reinforcer delivery. Response rate in the peak trials of the FIPP conformed to a temporally differentiated pattern, which was well described by a modified Gaussian function; in agreement with previous findings, the peak time occurred close to the time at which the reinforcer was delivered in the fixed-interval trials, and the Weber fraction was within the range of values reported previously. The density of Fos-positive neurones (counts mm−2) in the orbital prefrontal cortex (OPFC) was greater in rats exposed to the FIPP than in rats exposed to the VI schedule, suggesting a greater activation of this area during the performance of the former task. This is consistent with the results of previous studies that have implicated the OPFC in interval timing behaviour. However, there was no significant difference between the levels of Fos expression in the dorsal or ventral striatum of the rats trained under the two schedules.
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Affiliation(s)
- L. Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - C.M. Olarte-Sánchez
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - S. Body
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - K.C.F. Fone
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
- School of Biomedical Sciences, University of Nottingham, Room E20, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - C.M. Bradshaw
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
- Corresponding author. Tel.: +44 0115 823 0219; fax: +44 0115 823 0220.
| | - E. Szabadi
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
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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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Adriani W, Zoratto F, Romano E, Laviola G. Cognitive impulsivity in animal models: role of response time and reinforcing rate in delay intolerance with two-choice operant tasks. Neuropharmacology 2009; 58:694-701. [PMID: 19945469 DOI: 10.1016/j.neuropharm.2009.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 10/21/2009] [Accepted: 11/17/2009] [Indexed: 11/19/2022]
Abstract
Impulsivity, a key symptom of ADHD (attention-deficit hyperactivity disorder), is also common in obsessive-compulsive and addictive disorders. There is rising interest in animal models of inhibitory-control impairment. Adolescent rats were tested daily in the intolerance-to-delay (ID) task (session 25 min, timeout 20 s), involving choice between either immediate small amount of food (SS), or larger amount of food after a delay (LL). The mixed 5-HT(1A/7) agonist (8-OH-DPAT, 0 or 0.060 mg/kg i.p.) was administered acutely just before the last three sessions at highest delays. In addition to the classical choice parameter (percent LL preference), the spontaneous waiting (termed response time, RT) occurring between end of a timeout (TO) and next nose-poke was calculated. The pace between consecutive reinforcer deliveries is given by the mean inter-trial interval (mITI, i.e. TO + RT). Hence, the impact of any given delay may be proportional to this pace and be expressed as delay-equivalent odds, i.e. the extent by which delays are multiples of the mITI. Data revealed that RT/mITI increased sharply from around 15 s/35 s to around 30 s/50 s when imposed delay changed from 30 s to 45 s (i.e. odds from 0.91 to 1.06). This suggests that rats adopted a strategy allowing them to keep in pace with perceived reinforcing rate. The increasing delay constraint directly influenced the length of rats' spontaneous waiting (RT) before next decision. For higher delays, with odds >1, rats shifted to a clear-cut SS preference, which is devoid of any exogenous temporal constraint. A challenge with 8-OH-DPAT (0 or 0.060 mg/kg i.p.) decreased impulsive choice but also increased RT. Thus, tapping onto 5-HT(1A/7) receptors slightly enhanced RT/mITI values, possibly reflecting ability of rats to cope with slower reinforcing rates and/or with delay-cancelled reward paces. In summary, delay-induced states of aversion may arise from the innate tendency to rely on a regular rate of reinforcement. Conversely, a drug-enhanced capacity to cope with delay may involve an internal ability to adjust expectancy about such a reinforcing rate.
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Affiliation(s)
- Walter Adriani
- Section of Behavioural Neuroscience, Department of Cell Biology & Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
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10
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Buhusi CV, Meck WH. Relative time sharing: new findings and an extension of the resource allocation model of temporal processing. Philos Trans R Soc Lond B Biol Sci 2009; 364:1875-85. [PMID: 19487190 DOI: 10.1098/rstb.2009.0022] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Individuals time as if using a stopwatch that can be stopped or reset on command. Here, we review behavioural and neurobiological data supporting the time-sharing hypothesis that perceived time depends on the attentional and memory resources allocated to the timing process. Neuroimaging studies in humans suggest that timekeeping tasks engage brain circuits typically involved in attention and working memory. Behavioural, pharmacological, lesion and electrophysiological studies in lower animals support this time-sharing hypothesis. When subjects attend to a second task, or when intruder events are presented, estimated durations are shorter, presumably due to resources being taken away from timing. Here, we extend the time-sharing hypothesis by proposing that resource reallocation is proportional to the perceived contrast, both in temporal and non-temporal features, between intruders and the timed events. New findings support this extension by showing that the effect of an intruder event is dependent on the relative duration of the intruder to the intertrial interval. The conclusion is that the brain circuits engaged by timekeeping comprise not only those primarily involved in time accumulation, but also those involved in the maintenance of attentional and memory resources for timing, and in the monitoring and reallocation of those resources among tasks.
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Affiliation(s)
- Catalin V Buhusi
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29464, USA.
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11
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Timing with opportunity cost: concurrent schedules of reinforcement improve peak timing. Learn Behav 2009; 37:217-29. [PMID: 19542089 DOI: 10.3758/lb.37.3.217] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The temporal generalization gradient produced by the peak-interval (PI) procedure reflects behavior under the control of positive reinforcement for responding after the criterial time, but shows negligible discouragement for early responses. The lack of consequences for premature responding may affect estimates of timing accuracy and precision in the PI procedure. In two experiments, we sought to encourage more accurate timing in pigeons by establishing an opportunity cost for such responding. Concurrent ratio and interval schedules of reinforcement reduced the dispersion of keypecking around the target time. A sequence of three response-rate states (low-high-low) characterized performance in individual trials. Opportunity cost substantially reduced the mean and standard deviation of the duration of the middle-high state that typically enveloped the target time, indicating improved temporal acuity. We suggest a model as a first-order approximation to timing with opportunity cost.
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12
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Attenuation of the effects of d-amphetamine on interval timing behavior by central 5-hydroxytryptamine depletion. Psychopharmacology (Berl) 2009; 203:547-59. [PMID: 19018519 PMCID: PMC2761547 DOI: 10.1007/s00213-008-1400-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Accepted: 10/28/2008] [Indexed: 12/28/2022]
Abstract
RATIONALE Interval timing in the free-operant psychophysical procedure is sensitive to the monoamine-releasing agent d-amphetamine, the D(2)-like dopamine receptor agonist quinpirole, and the D(1)-like agonist 6-chloro-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzepine (SKF-81297). The effect of d-amphetamine can be antagonized by selective D(1)-like and 5-HT(2A) receptor antagonists. It is not known whether d-amphetamine's effect requires an intact 5-hydroxytryptamine (5-HT) pathway. OBJECTIVE The objective of this study was to examine the effects of d-amphetamine, quinpirole, and SKF-81297 on timing in intact rats and rats whose 5-hydroxytryptaminergic (5-HTergic) pathways had been ablated. MATERIALS AND METHODS Rats were trained under the free-operant psychophysical procedure to press levers A and B in 50-s 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 5-s epochs of the trials; logistic functions were fitted to the data for derivation of timing indices (T(50), time corresponding to %B = 50%; Weber fraction). The effects of d-amphetamine (0.4 mg kg(-1) i.p.), quinpirole (0.08 mg kg(-1) i.p.), and SKF-81297 (0.4 mg kg(-1) s.c.) were compared between intact rats and rats whose 5-HTergic pathways had been destroyed by intra-raphe injection of 5,7-dihydroxytryptamine. RESULTS Quinpirole and SKF-81297 reduced T(50) in both groups; d-amphetamine reduced T(50) only in the sham-lesioned group. The lesion reduced 5-HT levels by 80%; catecholamine levels were not affected. CONCLUSIONS d-Amphetamine's effect on performance in the free-operant psychophysical procedure requires an intact 5-HTergic system. 5-HT, possibly acting at 5-HT(2A) receptors, may play a 'permissive' role in dopamine release.
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Eagle DM, Lehmann O, Theobald DEH, Pena Y, Zakaria R, Ghosh R, Dalley JW, Robbins TW. Serotonin depletion impairs waiting but not stop-signal reaction time in rats: implications for theories of the role of 5-HT in behavioral inhibition. Neuropsychopharmacology 2009; 34:1311-21. [PMID: 19005464 DOI: 10.1038/npp.2008.202] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Central serotonin (5-HT) function is thought to be a critical component of behavioral inhibition and impulse control. However, in recent clinical studies, 5-HT manipulations failed to affect stop-signal reaction time (SSRT), which is a fundamental process in behavioral inhibition. We investigated the effect of central 5-HT depletion (intracerebroventricular 5,7-dihydroxytryptamine) in rats on two aspects of behavioral inhibition, SSRT and 'waiting', using the stop-signal task. 5-HT depletion had no effects on SSRT or any other primary measure on the stop-signal task. However, within the same task, there was a deficit in 'waiting' in 5-HT-depleted rats when they were required to withhold from responding in the terminal element of the stop-signal task for an extended period. D-Amphetamine had dose-dependent, but not 5-HT-dependent effects on SSRT. Conversely, the dose that tended to improve, or decrease, SSRT (0.3 mg/kg) impaired the ability to wait, again independently of 5-HT manipulation. These findings suggest that SSRT and 'waiting' are distinct measures of behavioral inhibition, and show that 5-HT is critical for some forms of behavioral inhibition but not others. This has significant implications for the treatment of conditions such as attention deficit and hyperactivity disorder, substance abuse, and affective disorders, in which inhibitory and impulse-control deficits are common.
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Affiliation(s)
- Dawn M Eagle
- Department of Experimental Psychology and the Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.
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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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15
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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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Cheung THC, Bezzina G, Body S, Fone KCF, Bradshaw CM, Szabadi E. Tolerance to the effect of 2,5-dimethoxy-4-iodoamphetamine (DOI) on free-operant timing behaviour: interaction between behavioural and pharmacological mechanisms. Psychopharmacology (Berl) 2007; 192:521-35. [PMID: 17333133 DOI: 10.1007/s00213-007-0743-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 02/09/2007] [Indexed: 12/25/2022]
Abstract
RATIONALE The psychostimulant d-amphetamine, the D(2/3) dopamine receptor agonist quinpirole and the 5-HT(2) receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) have similar effects on free-operant timing behaviour. There is evidence that tolerance develops to the effects of psychostimulants on timing performance during chronic treatment; this tolerance is generally attributed to behavioural adaptation rather than to pharmacological desensitisation. There have been no previous investigations of tolerance to the effect of DOI on free-operant timing behaviour. OBJECTIVE To demonstrate tolerance to DOI's effect on timing performance and to examine the nature of this tolerance. MATERIALS AND METHODS Rats were trained under the free-operant psychophysical procedure to press two levers (A and B) in 80-s 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 8-s epochs of the trials; logistic functions were fitted to the data from each rat for the derivation of timing indices (T (50) [time corresponding to %B = 50]; Weber fraction). RESULTS In experiment 1, DOI (0.25 mg kg(-1)) reduced T (50) compared to vehicle; tolerance to this effect was seen after repeated daily treatments with DOI if the rats were exposed to behavioural training during the period of treatment but not if the repeated treatments took place during a 'holiday' from behavioural training. In experiment 2, repeated treatment with DOI resulted in tolerance to the effect of DOI on T (50) and cross-tolerance to the effect of d-amphetamine (0.4 mg kg(-1)), but no cross-tolerance was seen to the effect of quinpirole (0.08 mg kg(-1)). CONCLUSIONS The results indicate that behavioural adaptation is involved in the development of tolerance to DOI's effect on timing. The finding of cross-tolerance to d-amphetamine but not to quinpirole suggests that the reduction of T (50) in the free-operant psychophysical procedure may be brought about by two distinct pharmacological mechanisms, one activated by DOI and d-amphetamine, and the other by quinpirole.
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Affiliation(s)
- T H C Cheung
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, UK.
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Sanabria F, Killeen PR. Temporal generalization accounts for response resurgence in the peak procedure. Behav Processes 2007; 74:126-41. [PMID: 17141981 DOI: 10.1016/j.beproc.2006.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 10/20/2006] [Accepted: 10/24/2006] [Indexed: 11/26/2022]
Abstract
The peak interval (PI) procedure is commonly used to evaluate animals' ability to produce timed intervals. It consists of presenting fixed interval (FI) schedules in which some of the trials are replaced by extended non-reinforced trials. Responding will often resume (resurge) at the end of the non-reinforced trials unless precautions are taken to prevent it. Response resurgence was replicated in rats and pigeons. Variation of the durations of the FI and the non-reinforced probe trials showed it to be dependent on the time when reinforcement is expected. Timing of both the normal time to reinforcement, and the subsequent time to reinforcement during the probe trials followed Weber's law. A quantitative model of resurgence is described, suggesting how animals respond to the signaling properties of reinforcement omission. Model results were simulated using a stochastic binary counter.
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Buhusi CV, Meck WH. Effect of clozapine on interval timing and working memory for time in the peak-interval procedure with gaps. Behav Processes 2006; 74:159-67. [PMID: 17141425 PMCID: PMC1849977 DOI: 10.1016/j.beproc.2006.10.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 10/09/2006] [Accepted: 10/09/2006] [Indexed: 01/26/2023]
Abstract
Previous research indicates that dopamine controls both the speed of an internal clock [Maricq, A.V., Church, R.M., 1983. The differential effects of haloperidol and methamphetamine on time estimation in the rat. Psychopharmacology 79, 10-15] and sharing of resources between the timer and other cognitive processes [Buhusi, C.V., 2003. Dopaminergic mechanisms of interval timing and attention. In: Meck, W.H. (Ed.), Functional and Neural Mechanisms of Interval Timing. CRC Press, Boca Raton, FL, pp. 317-338]. For example, dopamine agonist methamphetamine increases the speed of an internal clock and resets timing after a gap, while dopamine antagonist haloperidol decreases the speed of an internal clock and stops timing during a gap [Buhusi, C.V., Meck, W.H., 2002. Differential effects of methamphetamine and haloperidol on the control of an internal clock. Behav. Neurosci. 116, 291-297]. Using a 20-s peak-interval procedure with gaps we examined the acute effects of clozapine (2.0mg/kg i.p.), which exerts differential effects on dopamine and serotonin in the cortex and striatum, two brain areas involved in interval timing and working memory. Relative to saline, clozapine injections shifted the response functions leftward both in trials with and without gaps, suggesting that clozapine increased the speed of an internal clock and facilitated the maintenance of the pre-gap interval in working memory. These results suggest that clozapine exerts effects in different brain areas in a manner that allows for the pharmacological separation of clock speed and working memory as a function of peak trials without and with gaps.
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Affiliation(s)
- Catalin V Buhusi
- Duke University, Department of Psychology and Neuroscience, Durham, NC 27708, United States.
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Matell MS, Portugal GS. Impulsive responding on the peak-interval procedure. Behav Processes 2006; 74:198-208. [PMID: 17023122 PMCID: PMC1931419 DOI: 10.1016/j.beproc.2006.08.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 08/17/2006] [Accepted: 08/22/2006] [Indexed: 10/24/2022]
Abstract
The pattern of responding on a peak-interval timing task allows one to make inferences regarding the sources of variation that contribute to interval timing behavior. Non-temporal factors such as impulsivity may impact the validity of these inferences. Rats were trained on a 15s peak-interval procedure (PI) or a mixed 15s behaviorally dependent variable-interval, 15s peak-interval procedure (bdVIPI) for an extended number of sessions. Extended training on the PI revealed a bi-modal distribution in the times at which subjects started responding for temporally predictable reinforcement, suggesting that multiple processes contribute to the behavioral pattern obtained in this procedure. Training on the bdVIPI eliminated the early mode of this bi-modal distribution, thereby decreasing the variation in start times. These results suggest that alternative response options can modulate the influence of impulsivity in timing tasks.
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Affiliation(s)
- Matthew S Matell
- Department of Psychology, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, United States.
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