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Abstract
Comparative and cognitive psychologists interpret performance in different ways. Animal researchers invoke a dominant construct of associative learning. Human researchers acknowledge humans' capacity for explicit-declarative cognition. This article offers a way to bridge a divide that defeats productive cross-talk. We show that animals often challenge the associative-learning construct, and that it does not work to try to stretch the associative-learning construct to encompass these performances. This approach thins and impoverishes that important construct. We describe an alternative approach that restrains the construct of associative learning by giving it a clear operational definition. We apply this approach in several comparative domains to show that different task variants change-in concert-the level of awareness, the declarative nature of knowledge, the dimensional breadth of knowledge, and the brain systems that organize learning. These changes reveal dissociable learning processes that a unitary associative construct cannot explain but a neural-systems framework can explain. These changes define the limit of associative learning and the threshold of explicit cognition. The neural-systems framework can broaden empirical horizons in comparative psychology. It can offer animal models of explicit cognition to cognitive researchers and neuroscientists. It can offer simple behavioral paradigms for exploring explicit cognition to developmental researchers. It can enliven the synergy between human and animal research, promising a productive future for both.
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Affiliation(s)
- J David Smith
- Department of Psychology, Georgia State University, Atlanta, GA, 30303-5010, USA.
| | - Barbara A Church
- Language Research Center, Georgia State University, Atlanta, GA, 30303-5010, USA
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Connor DA, Gould TJ. The role of working memory and declarative memory in trace conditioning. Neurobiol Learn Mem 2016; 134 Pt B:193-209. [PMID: 27422017 PMCID: PMC5755400 DOI: 10.1016/j.nlm.2016.07.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/07/2016] [Accepted: 07/11/2016] [Indexed: 01/18/2023]
Abstract
Translational assays of cognition that are similarly implemented in both lower and higher-order species, such as rodents and primates, provide a means to reconcile preclinical modeling of psychiatric neuropathology and clinical research. To this end, Pavlovian conditioning has provided a useful tool for investigating cognitive processes in both lab animal models and humans. This review focuses on trace conditioning, a form of Pavlovian conditioning typified by the insertion of a temporal gap (i.e., trace interval) between presentations of a conditioned stimulus (CS) and an unconditioned stimulus (US). This review aims to discuss pre-clinical and clinical work investigating the mnemonic processes recruited for trace conditioning. Much work suggests that trace conditioning involves unique neurocognitive mechanisms to facilitate formation of trace memories in contrast to standard Pavlovian conditioning. For example, the hippocampus and prefrontal cortex (PFC) appear to play critical roles in trace conditioning. Moreover, cognitive mechanistic accounts in human studies suggest that working memory and declarative memory processes are engaged to facilitate formation of trace memories. The aim of this review is to integrate cognitive and neurobiological accounts of trace conditioning from preclinical and clinical studies to examine involvement of working and declarative memory.
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Affiliation(s)
- David A Connor
- Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA 19122, United States
| | - Thomas J Gould
- Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA 19122, United States.
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3
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Clark RE, Squire LR. Human Eyeblink Classical Conditioning: Effects of Manipulating Awareness of the Stimulus Contingencies. Psychol Sci 2016. [DOI: 10.1111/1467-9280.00099] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
In four groups, we either promoted or prevented awareness of the stimulus contingencies during trace or delay differential eyeblink classical conditioning. To reduce awareness of the stimulus contingencies, we asked two groups to engage in a secondary attention-demanding task during trace or delay conditioning. To promote awareness of the stimulus contingencies, we explained the relationships between the stimuli to two other groups before trace conditioning. One of these groups then engaged in the secondary task during conditioning. Following conditioning, awareness of the stimulus contingencies was assessed with a true/false questionnaire. Preventing awareness of the stimulus contingencies disrupted trace differential eyeblink conditioning but did not affect delay differential conditioning. Providing knowledge about the stimulus contingencies facilitated trace conditioning. Finally, providing knowledge about the stimulus contingencies, then having subjects engage in a distraction task, disrupted trace conditioning. Results are discussed in terms of the role of declarative and nondeclarative memory systems during trace eyeblink conditioning.
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Affiliation(s)
- Robert E. Clark
- Department of Psychiatry, University of California, San Diego
| | - Larry R. Squire
- Veterans Affairs Medical Center, San Diego, and Departments of Psychiatry and Neurosciences, University of California, San Diego
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Tracy JA, Ghose SS, Stecher T, McFall RM, Steinmetz JE. Classical Conditioning in a Nonclinical Obsessive-Compulsive Population. Psychol Sci 2016. [DOI: 10.1111/1467-9280.00098] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Obsessive-compulsive disorder (OCD) is an intrusive and debilitating condition in which the individual experiences uncontrollable thoughts, compulsions, and urges. Successful treatments for OCD are based on Mowrer's theory of fear and avoidance behavior, which predicts that OCD subjects should show accelerated associative conditioning. This prediction was tested in two experiments that compared the classical eyeblink conditioning of OCD-like and control college students. OCD and control subjects learned normally and similarly when the conditioning procedure was accompanied by an active visual search background task (Experiment 1). However, when the background task was changed so that subjects passively viewed neutral pictures, OCD subjects conditioned significantly faster than control subjects (Experiment 2). Overall, the performance of all subjects in Experiment 1 was superior to the performance of subjects in Experiment 2.
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Weidemann G, Best E, Lee JC, Lovibond PF. The role of contingency awareness in single-cue human eyeblink conditioning. Learn Mem 2013; 20:363-6. [PMID: 23774766 DOI: 10.1101/lm.029975.112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Single-cue delay eyeblink conditioning is presented as a prototypical example of automatic, nonsymbolic learning that is carried out by subcortical circuits. However, it has been difficult to assess the role of cognition in single-cue conditioning because participants become aware of the simple stimulus contingency so quickly. In this experiment (n = 166), we masked the contingency to reduce awareness. We observed a strong relationship between contingency awareness and conditioned responding, with both trace and delay procedures. This finding suggests that explicit associative knowledge and anticipatory behavior are regulated by a coordinated system rather than by functionally and neurally distinct systems.
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Affiliation(s)
- Gabrielle Weidemann
- School of Social Sciences and Psychology, University of Western Sydney, Sydney, 2751, Australia.
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Lovibond PF, Liu JCJ, Weidemann G, Mitchell CJ. Awareness is necessary for differential trace and delay eyeblink conditioning in humans. Biol Psychol 2011; 87:393-400. [PMID: 21586313 DOI: 10.1016/j.biopsycho.2011.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 04/29/2011] [Accepted: 05/02/2011] [Indexed: 10/18/2022]
Abstract
Squire et al. have proposed that trace and delay eyeblink conditioning procedures engage separate learning systems: a declarative hippocampal/cortical system associated with conscious contingency awareness, and a reflexive sub-cortical system independent of awareness, respectively (Clark and Squire, 1998; Smith et al., 2005). The only difference between these two procedures is that the conditioned stimulus (CS) and the unconditioned stimulus (US) overlap in delay conditioning, whereas there is a brief interval (e.g., 1s) between them in trace conditioning. In two experiments using the same procedure as Clark and Squire's group, we observed differential conditioning only in participants who showed contingency awareness in a post-experimental questionnaire, with both trace and delay procedures. We interpret these results to suggest that, although there may be multiple brain regions involved in learning, these regions are organized as a coordinated system rather than as separate, independent systems.
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Affiliation(s)
- Peter F Lovibond
- School of Psychology, University of New South Wales, Sydney NSW 2052, Australia.
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Woodruff-Pak DS, Tobia MJ, Jiao X, Beck KD, Servatius RJ. Preclinical investigation of the functional effects of memantine and memantine combined with galantamine or donepezil. Neuropsychopharmacology 2007; 32:1284-94. [PMID: 17119537 DOI: 10.1038/sj.npp.1301259] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Combinations of drugs approved to treat Alzheimer's disease (AD) were tested in older rabbits with delay eyeblink classical conditioning, a form of associative learning severely impaired in AD. In Experiment 1 (n=49 rabbits), low doses (0.1, 0.5, 1.0, and 0.0 (vehicle) mg/kg) of memantine (Namenda) were tested. These three doses neither improved nor impaired acquisition at a statistically significant level. The 0.5 mg/kg dose had the greatest effect numerically and did not cause sensitization or habituation in explicitly unpaired controls. In Experiment 2 (n=56), doses of galantamine (Razadyne; 3.0 mg/kg) and donepezil (Aricept; 0.75 mg/kg) that had comparable magnitudes of cholinesterase inhibition were tested alone and in combination with 0.5 mg/kg memantine. Older rabbits treated with galantamine and with galantamine+memantine learned significantly better than vehicle-treated rabbits, but adding memantine did not improve learning over galantamine alone. Older rabbits treated with donepezil or a combination of memantine and donepezil did not learn significantly better than rabbits treated with vehicle. Galantamine has two mechanisms of action: mild cholinesterase inhibition and allosteric modulation of nicotinic acetylcholine receptors (nAChRs). When equated for cholinesterase inhibition, galantamine had significant efficacy in the eyeblink conditioning model system, but donepezil did not, indicating that modulation of nAChRs may be the mechanism that significantly ameliorates learning deficits in this model. In the absence of AD neuropathology in older rabbits, memantine had no efficacy alone or in combination with the other drugs.
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Brignell CM, Curran HV. Drugs, sweat, and fears: a comparison of the effects of diazepam and methylphenidate on fear conditioning. Psychopharmacology (Berl) 2006; 186:504-16. [PMID: 16758238 DOI: 10.1007/s00213-006-0363-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Accepted: 02/28/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE Classical conditioning of a fear response involves the formation of an association between a stimulus and an emotional response and can be seen as a basic form of emotional memory. While both benzodiazepines and stimulant drugs may influence the formation of episodic memories for emotional events, their effects on fear conditioning are less clear. OBJECTIVES This study compared the effects of diazepam with methylphenidate on fear conditioning. MATERIALS AND METHODS In a single-session between groups design with three conditions [placebo, diazepam (10 mg), and methylphenidate (40 mg)], classical conditioning of a skin conductance response to a visual stimulus previously paired with a 100-db white noise was tested in 45 healthy volunteers. RESULTS Diazepam blocked fear conditioning, despite responses to the unconditioned aversive stimulus and neutral control stimulus being unimpaired. Conditioning remained intact after methylphenidate. Conditioned responses were not extinguished completely by the end of the experiment, and it was not possible to draw conclusions about the effects of the drugs on extinction. CONCLUSIONS Although diazepam has well-documented amnesic effects, it has not been found to affect implicit forms of memory like perceptual and conceptual priming. As the present study found impaired fear conditioning after diazepam, it adds weight to recent findings that emotional memories are disproportionately impaired by the benzodiazepines.
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Affiliation(s)
- Catherine M Brignell
- School of Psychology, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
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Smith CN, Clark RE, Manns JR, Squire LR. Acquisition of differential delay eyeblink classical conditioning is independent of awareness. Behav Neurosci 2005; 119:78-86. [PMID: 15727514 PMCID: PMC2773180 DOI: 10.1037/0735-7044.119.1.78] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There has been debate about whether differential delay eyeblink conditioning can be acquired without awareness of the stimulus contingencies. In 4 experiments, the authors reexamined this question. Older participants were tested with a tone and white noise (Experiment 1) or with 2 tones (Experiment 2). In addition, younger participants were tested with 2 tones (Experiment 3) or with 2 tones plus the parameters from an earlier study that had reported a relationship between conditioning and awareness (Experiment 4). Participants who were designated aware of the stimulus contingencies and participants who were designated unaware exhibited equivalent levels of differential eyeblink conditioning. Awareness of stimulus contingencies is not required for differential delay eyeblink conditioning when simple conditioned stimuli are used.
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Affiliation(s)
- Christine N Smith
- Institute for Neural Computation, University of California, San Diego, CA, USA
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Clark RE, Squire LR. The importance of awareness for eyeblink conditioning is conditional: theoretical comment on Bellebaum and Daum (2004). Behav Neurosci 2005; 118:1466-8. [PMID: 15598158 DOI: 10.1037/0735-7044.118.6.1466] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Eyeblink conditioning entails a variety of paradigms that differ in terms of the brain systems that support conditioning and the importance of awareness. In this issue, C. Bellebaum and I. Daum (2004) that reports that conditional discrimination learning depends on awareness. Their findings, along with other recent work, suggest a framework whereby the temporal features of the conditioning paradigm are critical in determining the ability of the cerebellum to support conditioning and, as a result, the role of awareness in conditioning.
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Affiliation(s)
- Robert E Clark
- Veterans Affairs Medical Center, San Diego, CA 92161, USA
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Labar KS, Cook CA, Torpey DC, Welsh-Bohmer KA. Impact of healthy aging on awareness and fear conditioning. Behav Neurosci 2005; 118:905-15. [PMID: 15506873 DOI: 10.1037/0735-7044.118.5.905] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fear conditioning has provided a useful model system for studying associative emotional learning, but the impact of healthy aging has gone relatively unexplored. The present study investigated fear conditioning across the adult life span in humans. A delay discrimination task was employed using visual conditioned stimuli and an auditory unconditioned stimulus. Awareness of the reinforcement contingencies was assessed in a postexperimental interview. Compared with young adult participants, middle-aged and older adults displayed reductions in unconditioned responding, discriminant conditioning, and contingency awareness. When awareness and overall arousability were taken into consideration, there were no residual effects of aging on conditioning. These results highlight the importance of considering the influence of declarative knowledge when interpreting age-associated changes in discriminative conditioned learning.
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Affiliation(s)
- Kevin S Labar
- Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708-0999, USA.
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12
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Abstract
Memory is composed of several different abilities that are supported by different brain systems. The distinction between declarative (conscious) and nondeclarative (non-conscious) memory has proved useful in understanding the nature of eyeblink classical conditioning - the best understood example of classical conditioning in vertebrates. In delay conditioning, the standard procedure, conditioning depends on the cerebellum and brainstem and is intact in amnesia. Trace conditioning, a variant of the standard procedure, depends additionally on the hippocampus and neocortex and is impaired in amnesia. Recent studies have sharpened the contrast between delay and trace conditioning by exploring the importance of awareness. We discuss these new findings in relation to the brain systems supporting eyeblink conditioning and suggest why awareness is important for trace conditioning but not for delay conditioning.
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Affiliation(s)
- Robert E. Clark
- Dept of Psychiatry, University of California, San Diego, USA
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13
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The role of awareness in Pavlovian conditioning: Empirical evidence and theoretical implications. ACTA ACUST UNITED AC 2002. [DOI: 10.1037/0097-7403.28.1.3] [Citation(s) in RCA: 310] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Manns JR, Clark RE, Squire LR. Standard delay eyeblink classical conditioning is independent of awareness. ACTA ACUST UNITED AC 2002. [DOI: 10.1037/0097-7403.28.1.32] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Clark RE, Manns JR, Squire LR. Trace and delay eyeblink conditioning: contrasting phenomena of declarative and nondeclarative memory. Psychol Sci 2001; 12:304-8. [PMID: 11476097 DOI: 10.1111/1467-9280.00356] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We tested the proposal that trace and delay eyeblink conditioning aref fundamentally different kinds of learning. Strings of one, two, three, or four trials with the conditioned stimulus (CS) alone and strings of one, two, three, or four trials with paired presentations of both the CS and the unconditioned stimulus (US) occurred in such a way that the probability of a US was independent of string length. Before each trial, participants predicted the likelihood of the US on the next trial. During both delay (n = 20) and trace (n = 18) conditioning, participants exhibited high expectation of the US following strings of CS-alone trials and low expectation of the US following strings of CS-US trials--a phenomenon known as the gambler's fallacy. During delay conditioning, conditioned responses (CRs) were not influenced by expectancy but by the associative strength of the CS and US. Thus, CR probability was high following a string of CS-US trials and low following a string of CS-alone trials. The results for trace conditioning were opposite. CR probability was high when expectancy of the US was high and low when expectancy of the US was low: The results show that trace and delay eyeblink conditioning are fundamentally different phenomena. We consider how the findings can be understood in terms of the declarative and nondeclarative memory systems that support eyeblink classical conditioning.
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Affiliation(s)
- R E Clark
- Department of Psychiatry, University of California, San Diego, USA
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Manns JR, Clark RE, Squire LR. Parallel acquisition of awareness and trace eyeblink classical conditioning. Learn Mem 2000; 7:267-72. [PMID: 11040257 PMCID: PMC311341 DOI: 10.1101/lm.33400] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Trace eyeblink conditioning (with a trace interval >/=500 msec) depends on the integrity of the hippocampus and requires that participants develop awareness of the stimulus contingencies (i.e., awareness that the conditioned stimulus [CS] predicts the unconditioned stimulus [US]). Previous investigations of the relationship between trace eyeblink conditioning and awareness of the stimulus contingencies have manipulated awareness or have assessed awareness at fixed intervals during and after the conditioning session. In this study, we tracked the development of knowledge about the stimulus contingencies trial by trial by asking participants to try to predict either the onset of the US or the onset of their eyeblinks during differential trace eyeblink conditioning. Asking participants to predict their eyeblinks inhibited both the acquisition of awareness and eyeblink conditioning. In contrast, asking participants to predict the onset of the US promoted awareness and facilitated conditioning. Acquisition of knowledge about the stimulus contingencies and acquisition of differential trace eyeblink conditioning developed approximately in parallel (i.e., concurrently).
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Affiliation(s)
- J R Manns
- Department of Psychology, University of California, San Diego, California 92039, USA
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Abstract
For the past 50 years, psychologists have wrestled with questions regarding the relationship between conscious awareness and human conditioned behavior. A recent proposal that the hippocampus mediates awareness during trace conditioning (Clark, Squire, Science 1998;280:77-81) has extended the awareness-conditioning debate to the neuroscience arena. In the following commentary, we raise specific theoretical and methodological issues regarding the Clark and Squire study and place their finding into a broader context. Throughout our discussion, we consider the difficulties in assessing subjective awareness, the importance of establishing necessary and sufficient conditions for cognitive mediation effects, the influence of conditioned response modality, and the nature of hippocampal requirements across conditioning protocols. It is clear that trace eyeblink conditioning is a hippocampal-dependent task, but whether awareness is a necessary component of trace conditioning is not definitively proven. We propose that future functional neuroimaging studies and behavioral experiments using on-line measures of awareness may help clarify the relationship among classical conditioning, awareness, and the hippocampus.
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Affiliation(s)
- K S LaBar
- Cognitive Neurology and Alzheimer's Disease Center, Department of Neurology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Abstract
Classical conditioning of the eye-blink response, perhaps the best studied example of associative learning in vertebrates, is relatively automatic and reflexive, and with the standard procedure (simple delay conditioning), it is intact in animals with hippocampal lesions. In delay conditioning, a tone [the conditioned stimulus (CS)] is presented just before an air puff to the eye [the unconditioned stimulus (US)]. The US is then presented, and the two stimuli coterminate. In trace conditioning, a variant of the standard paradigm, a short interval (500 to 1000 ms) is interposed between the offset of the CS and the onset of the US. Animals with hippocampal lesions fail to acquire trace conditioning. Amnesic patients with damage to the hippocampal formation and normal volunteers were tested on two versions of delay conditioning and two versions of trace conditioning and then assessed for the extent to which they became aware of the temporal relationship between the CS and the US. Amnesic patients acquired delay conditioning at a normal rate but failed to acquire trace conditioning. For normal volunteers, awareness was unrelated to successful delay conditioning but was a prerequisite for successful trace conditioning. Trace conditioning is hippocampus dependent because, as in other tasks of declarative memory, conscious knowledge must be acquired across the training session. Trace conditioning may provide a means for studying awareness in nonhuman animals, in the context of current ideas about multiple memory systems and the function of the hippocampus.
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Affiliation(s)
- R E Clark
- Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA
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