The Ontogeny of Human Learning in Delay, Long-Delay, and Trace Eyeblink Conditioning.

The ontogeny of associative learning in delay (750-ms conditional stimulus [CS], 650-ms interstimulus interval [ISI]), long-delay (1,350-ms CS, 1,250-ms ISI), and trace (750-ms CS, 500-ms trace interval, 1,250-ms ISI) eyeblink conditioning was examined in 5-month-old human infants and adults. Infants and adults showed different acquisition rates but reached equivalent asymptotes of conditional responses (CRs) in standard delay conditioning. In long-delay and trace conditions, infants exhibited less robust conditioning than adults and minimal ability to appropriately time CRs. During infancy, the ISI, rather than the conditioning procedure, predicted rate and effectiveness of CRs. These findings suggest that higher order cognitive abilities begin emerging early in development. Across ontogeny, however, there are changes in the limits and parameters that support associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eyeblink classical conditioning in the preweanling lamb.

Classical conditioning of eyeblink responses has been one of the most important models for studying the neurobiology of learning, with many comparative, ontogenetic, and clinical applications. The current study reports the development of procedures to conduct eyeblink conditioning in preweanling lambs and demonstrates successful conditioning using these procedures. These methods will permit application of eyeblink conditioning procedures in the analysis of functional correlates of cerebellar damage in a sheep model of fetal alcohol spectrum disorders, which has significant advantages over more common laboratory rodent models. Because sheep have been widely used for studies of pathogenesis and mechanisms of injury with many different prenatal or perinatal physiological insults, eyeblink conditioning can provide a well-studied method to assess postnatal behavioral outcomes, which heretofore have not typically been pursued with ovine models of developmental insults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delay discrimination and reversal eyeblink classical conditioning in abstinent chronic alcoholics.

[Correction Notice: An erratum for this article was reported in Vol 23(2) of Neuropsychology (see record 2009-02621-003). The lifetime drinking data listed in Table 1 on p. 198 was not correctly calculated and underestimated lifetime exposure to alcohol. The corrected lifetime variables from that table are included.] Evidence has shown that alcoholism leads to volume reductions in brain regions critical for associative learning using the eyeblink classical conditioning paradigm (EBCC). Evidence indicates that cerebellar shrinkage causes impairment in simple forms of EBCC, whereas changes in forebrain structures result in impairment in more complex tasks. In this study, the ability of abstinent alcoholics and matched control participants to acquire learned responses during delay discrimination and discrimination reversal was examined and related to severity of drinking history and neuropsychological performance. During discrimination learning, one tone (CS+) predicted the occurrence of an airpuff (unconditioned stimulus), and another tone (CS-) served as a neutral stimulus; then the significance of the tones was reversed. Alcoholics who learned the initial discrimination were impaired in acquiring the new CS+ after the tones reversed; this is a function that has previously been linked to forebrain structures. It is suggested that a factor important to alcoholic addiction may be the presence of alcoholic-related associative responses that interfere with the ability to learn new more adaptive associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Theta-Contingent Trial Presentation Accelerates Learning Rate and Enhances Hippocampal Plasticity During Trace Eyeblink Conditioning.

Hippocampal theta activity has been established as a key predictor of acquisition rate in rabbit (Orcytolagus cuniculus) classical conditioning. The current study used an online brain-computer interface to administer conditioning trials only in the explicit presence or absence of spontaneous theta activity in the hippocampus-dependent task of trace conditioning. The findings indicate that animals given theta-contingent training learned significantly faster than those given nontheta-contingent training. In parallel with the behavioral results, the theta-triggered group, and not the nontheta-triggered group, exhibited profound increases in hippocampal conditioned unit responses early in training. The results not only suggest that theta-contingent training has a dramatic facilitory effect on trace conditioning but also implicate theta activity in enhancing the plasticity of hippocampal neurons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial Prefrontal Lesions and Pavlovian Eyeblink and Heart Rate Conditioning: Effects of Partial Reinforcement on Delay and Trace Conditioning in Rabbits (Oryctolagus cuniculus).

Effects of continuous (100%) versus partial (25%) reinforcement were studied on Pavlovian delay and trace eyeblink conditioning in rabbits (Oryctolagus cuniculus) with either lesions to the medial prefrontal cortex (mPFC) or sham lesions. Concomitant heart rate changes evoked by the conditioned stimulus were also assessed. Partial reinforcement retarded eyeblink conditioning in both the trace and delay paradigm, but this impairment was greater during trace conditioning and in rabbits with mPFC lesions. Accompanying conditioned stimulus-evoked heart rate slowing was attenuated under all conditions by the mPFC lesions, although this result was not always statistically significant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Age and Awareness on Eyeblink Conditional Discrimination Learning.

The present study aimed to assess the effects of aging and awareness on conditional discrimination learning within an eyeblink conditioning procedure by using a consecutive age-groups design (20-35 years, 36-50 years, 51-65 years, 66-80 years). Increasing age was associated with a decline in overall eyeblink conditioned response (CR) frequency and a deficit in conditional discrimination learning in the 2 older groups. Awareness of stimulus contingencies affected discrimination performance but not overall CR rates in younger subjects. Older subjects did not achieve eyeblink conditional discrimination learning, regardless of awareness. Discrimination performance correlated with measures of declarative memory. The pattern of results is discussed with respect to the involvement of hippocampal-cerebellar interactions and awareness in the mediation of age-related conditioning changes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-Term Storage of an Associative Memory Trace in the Cerebellum.

Distinct neural regions may be engaged during acquisition and maintenance of some memories. In delay classical conditioning of the eyeblink response, the cerebellum is necessary for acquisition and expression of the conditioned response (CR), but loci of long-term memory storage are not known. Rabbits (Oryctolagus cuniculus) were trained, overtrained, and given either 30 additional days of training or 30 days of rest. Half the subjects in the rest group were given a reminder training session. Subjects then received either reversible inactivation of the cerebellar interpositus nucleus (muscimol) or permanent electrolytic lesions. In all cases, inactivation and lesions of the interpositus completely abolished the CR. The site of memory formation in the interpositus nucleus also appears to be the site of long-term memory storage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exploration of cerebellar-dependent associative learning in schizophrenia: Effects of varying and shifting interstimulus interval on eyeblink conditioning.

Eyeblink conditioning abnormalities have been reported in schizophrenia, but the extent to which these anomalies are evident across a range of delay intervals (i.e., interstimulus intervals; ISIs) is unknown. In addition, the effects of ISI shifts on learning are unknown, though such manipulations can be informative about the plasticity of cerebellar timing functions. Therefore, the primary purpose of the present study was to investigate the interactions between ISI manipulations and learning in schizophrenia. A standard delay eyeblink conditioning procedure with four different interstimulus intervals (ISIs; 250, 350, 550, 850 ms) was employed. Each eyeblink conditioning experiment was immediately followed by another with a different ISI, thus permitting the characterization of conditioned response (CR) learning at one ISI and the extent to which CRs could be generated at a different latency following an ISI shift. Collapsing across all conditions, the schizophrenia group (n = 55) had significantly fewer conditioned responses and longer onset latencies than age-matched controls (n = 55). Surprisingly, shifting to a new ISI had negligible effects on conditioned response rates in both groups. These findings contribute to evidence of robust eyeblink conditioning abnormalities in schizophrenia and suggest impaired cerebellar function, but underscore the need for more research to clarify the source of these abnormalities and their relationship to clinical manifestations of schizophrenia. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Bilateral nature of the conditioned eyeblink response in the rabbit: Behavioral characteristics and potential mechanisms.

In Pavlovian eyeblink conditioning, the conditioned response (CR) is highly lateralized to the eye to which the unconditioned stimulus (US) has been directed. However, the initial conditioning of one eye can facilitate subsequent conditioning of the other eye, a phenomenon known as the intereye transfer (IET) effect. Because a conditioned emotional response (CER), as well as the eyeblink CR, is acquired during eyeblink conditioning and influences the development of the CR, the CER acquired in initial training can plausibly account for the IET effect. To evaluate this possibility, the present study utilized previously determined eyeblink conditioning procedures that effectively decouple the degree of CER and CR development to investigate the IET effect. In each of 3 experiments rabbits were initially trained with comparison procedures that differentially favored the development of the eyeblink CR or the CER, prior to a shift of the US to the alternate eye. The observed differences in the IET suggest that the effect depends largely on the specific development of eyeblink CRs rather than the CER. The neurobiological implications of this apparent bilaterality of the eyeblink CR are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eyeblink Classical Conditioning to Auditory and Olfactory Stimuli: Performance Among Older Adults With and Without the Apolipoprotein E ε4 Allele.

Patients with Alzheimer's disease (AD) demonstrate slowed acquisition of the conditioned response (CR) in eyeblink classical conditioning paradigms (EBCC), although it is unknown how early in the course of the disease CR acquisition is affected. This study investigated whether changes in the rate of CR acquisition were apparent in nondemented older adults at greater genetic risk for developing AD (i.e., carriers of the apolipoprotein E [APOE] ε4 allele). Both ε4+ and ε4- participants demonstrated CR acquisition to auditory and olfactory CSs; however, rate of acquisition to the olfactory CS was significantly slower in ε4+ persons. Both groups acquired the CR to an auditory CS at the same rate. Results support olfactory compromise in the earliest stages of the AD disease process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Importance of Awareness for Eyeblink Conditioning Is Conditional: Theoretical Comment on Bellebaum and Daum (2004).

Comments on an article by C. Bellebaum and I. Daum (2004; see record 2004-21410-001) 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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amygdalar unit activity during three learning tasks: Eyeblink classical conditioning, Pavlovian fear conditioning, and signaled avoidance conditioning.

Neural activity in central and basolateral amygdala nuclei (CeA and BLA, respectively) was recorded during delay eyeblink conditioning, Pavlovian fear conditioning, and signaled barpress avoidance. During paired training, the CeA exhibited robust learning-related excitatory activity during all 3 tasks. By contrast, the BLA exhibited minimal activity during eyeblink conditioning, while demonstrating pronounced increases in learning-related excitatory responsiveness during fear conditioning and barpress avoidance. In addition, the relative amount of amygdalar activation observed appeared to be related to the relative intensity of the unconditioned stimulus and somatic requirements of the task. Results suggest the CeA mediates the Pavlovian association between sensory stimuli and the BLA mediates the modulation of instrumental responding through the assignment of motivational value to the unconditioned stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal Brain Magnetic Activity: Effects of Memory Task Demands.

Changes in spatiotemporal profiles of brain magnetic activity were investigated in healthy volunteers as a function of varying demands for phonological storage of spoken pseudowords. Greater activity for the phonological memory task was restricted to the dorsolateral prefrontal cortex (DLPFC) in the left hemisphere. During performance of the memory task, activity was initially found in the left superior temporal gyrus (between 100 and 200 ms), followed by activity in the ventrolateral prefrontal, motor, and premotor cortices (between 200 and 300 ms). Activity in DLPFCs was first observed consistently across participants later, between 300 and 400 ms. The data are consistent with the purported role of posterior temporal cortices in phonological analysis and in the online storage of phonological information, the contribution of ventrolateral and motor processing areas in establishment and short-term maintenance of articulatory representations through rehearsal, and the role of DLPFCs in the executive control of the maintenance operation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eyeblink conditioning in the rabbit (Oryctolagus cuniculus) with stimulation of the mystacial vibrissae as a conditioned stimulus.

Eyeblink conditioning is a well-understood paradigm for the study of learning and memory and has been successfully employed with the use of auditory and visual conditioned stimuli (CSs). In this study, vibrotactile stimulation of the mystacial vibrissae was examined as an alternative CS in the rabbit ( Oryctolagus cuniculus). The technique is described and acquisition of eyeblink conditioning (EBC) with stimulation of a single row of vibrissae in a delay paradigm is reported. Extinction of EBC with presentation of the CS alone is demonstrated, as well as reacquisition with stimulation of a single whisker. Finally, control experiments ensure that the CS has no auditory components. Ipsilateral presentation of the CS and airpuff is a more effective combination for training than contralateral presentations. Vibrotactile stimulation of the vibrissae as a CS will enable further examination of the neural correlates of learning in a well-characterized sensory system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Outcome Specificity of Learned Predictiveness Effects: Parallels Between Human Causal Learning and Animal Conditioning.

Two experiments examined the outcome specificity of a learned predictiveness effect in human causal learning. Experiment 1 indicated that prior experience of a cue-outcome relation modulates learning about that cue with respect to a different outcome from the same affective class but not with respect to an outcome from a different affective class. Experiment 2 ruled out an interpretation of this effect in terms of context specificity. These results indicate that learned predictiveness effects in human causal learning index an associability that is specific to a particular class of outcomes. Moreover, they mirror demonstrations of the reinforcer specificity of analogous effects in animal conditioning, supporting the suggestion that, under some circumstances, human causal learning and animal conditioning reflect the operation of common associative mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The bed nucleus of the stria terminalis is critically involved in enhancing associative learning after stressful experience.

Exposure to an acute stressful event enhances trace eyeblink conditioning in male rats, even when rats begin training days after the stressor (Shors, 2001). The authors examined whether the bed nucleus of the stria terminalis (BNST), an area involved in stress and anxiety, is critically involved in this effect and, if so, when. The authors found that excitotoxic lesions to the BNST prevented the enhanced conditioning after stressor exposure. In addition, temporary inactivation of the BNST during the stressor did not alter enhanced responding, whereas inactivation during training prevented the enhancement. These data indicate that stressful experience induces persistent changes in the BNST that are necessary for enhancing learning well after the stressful event has ceased. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of aging in delay and trace human eyeblink conditioning.

Normal aging has been shown to impact performance during human eyeblink classical conditioning, with older adults showing lower conditioning levels than younger adults. Previous findings showed younger adults can acquire both delay and trace conditioning concurrently, but it is not known whether older adults can learn under the same conditions. Present results indicated older adults did not produce a significantly greater number of conditioned responses during acquisition, but their ability to time eyeblink responses prior to the unconditioned stimulus was preserved. The decline in eyeblink conditioning that typically accompanies aging has been extended to concurrent presentations of delay and trace conditioning trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociations between expectancy and performance in simple and two-choice reaction-time tasks: A test of associative and nonassociative explanations.

Perruchet, Cleeremans, and Destrebecqz (2006) reported a striking dissociation between trends in the conscious expectancy of an event and the speed of a response that is cued by that event. They argued that this indicates the operation of independent processes in human associative learning. However, there remains a strong possibility that this dissociation is not a consequence of associative learning and is instead caused by changes in vigilance or sensitivity based on the recency of events on previous trials. Three experiments tested this possibility with versions of a cued reaction time task in which trends in performance could not be explained by these nonassociative factors. Experiment 1 introduced a dual-response version of the task, in which response-related vigilance should be held relatively constant, and Experiments 2 and 3 used a differential conditioning procedure to separate the influence of recent response cue presentation from the recent associative history of the trial events. In all experiments, similar trends in reaction time were evident, suggesting a genuine influence of associative learning on response performance. Experiment 3 demonstrated that the associative contribution to these trends was not caused by commensurate changes in expectancy of the response cue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Single Neurons in the Dentate Gyrus and CA1 of the Hippocampus Exhibit Inverse Patterns of Encoding During Trace Fear Conditioning.

Trace fear conditioning is a hippocampus-dependent learning task that requires the association of an auditory conditioned stimulus (CS) and a shock unconditioned stimulus (US) that are separated by a 20-s trace interval. Single-neuron activity was recorded simultaneously from the dentate gyrus (DG) and CA1 of rats during unpaired pseudoconditioning and subsequent trace fear conditioning. Single neurons in DG showed a progressive increase in learning-related activity to the CS and US across trace fear conditioning. Single neurons in CA1 showed an early increase in responding to the CS, which developed into a decrease in firing later in trace conditioning. Correlation analyses showed that DG and CA1 units exhibit inverse patterns of responding to the CS during trace fear conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)