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Results for “Conditioning, Classical”

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At least 235 records · Page 13Linked to original sources

PubMed1989

A classical conditioning procedure for the hearing assessment of multiply handicapped persons.

The present study evaluated the viability of a classical conditioning procedure with an air puff as unconditioned stimulus for the hearing assessment of multiply handicapped children and adolescents. All subjects were also exposed to operant conditioning, which consisted of a modified visual reinforcement audiometry (VRA) procedure or involved edible reinforcement contingent on a reaching response (for blind subjects). The findings indicate that the classical conditioning procedure was successful with 21 of the 23 subjects, whereas operant conditioning succeeded with 15 of the subjects. Thresholds obtained with classical conditioning were mostly equal to or within 10 dB of those obtained with operant conditioning and also matched previously available hearing estimates. These findings seem to suggest that the classical procedure can be a useful behavioral alternative for audiological assessment.

Adolescent↗

PubMed1999

Inactivation of interposed nuclei in the cat: classically conditioned withdrawal reflexes, voluntary limb movements and the action primitive hypothesis.

The cerebellar interposed nuclei are considered critical components of circuits controlling the classical conditioning of eyeblink responses in several mammalian species. The main purpose of the present experiments was to examine whether the interposed nuclei are also involved in the control of classically conditioned withdrawal responses in other skeletomuscular effector systems. To achieve this objective, a unique learning paradigm was developed to examine classically conditioned withdrawal responses in three effector systems (the eyelid, forelimb and hindlimb) in individual cats. Trained animals were injected with muscimol in the cerebellar interposed nuclei, and the effects on the three conditioned responses (CRs) were examined. Although the effects of muscimol were less dramatic than previously reported in the rabbit eyeblink preparation, the inactivation of the cerebellar nuclei affected the performance of CRs in all three effector systems. In additional experiments, animals were injected with muscimol at the sites affecting classically conditioned withdrawal responses to determine the effects of these injections on reaching and locomotion behaviors. These tests demonstrated that the same regions of the cerebellar interposed nuclei which control withdrawal reflexes are also involved in the control of limb flexion and precision placement of the paw during both locomotion and reaching tasks. The obtained data indicate that the interposed nuclei are involved in the control of ipsilateral action primitives and that inactivating the interposed nuclei affects several modes of action of these functional units.

Animals↗

PubMed1995

Age-related deficits in retention of the classically conditioned nictitating membrane response in rabbits.

Young and aged rabbits underwent classical conditioning of the nictitating membrane response (NMR) to a tone conditioned stimulus (CS) and a corneal airpuff unconditioned stimulus (UCS) for 18 consecutive days. Rabbits were then returned to their home cages for a 90-day period in which they received no further conditioning, but they were handled daily. On Day 91 they underwent retention testing during which the CS alone was presented 20 times. This was immediately followed by reacquisition in which the CS and UCS were again paired for 100 trials. Reacquisition was repeated on the following day. As in previous studies, aged rabbits acquired the conditioned response (CR) more slowly than young rabbits; however, by the end of acquisition, both groups reached similar asymptotic levels. Retention of the CR was significantly lower for aged than young rabbits. Reacquisition was also retarded in aged vs. young rabbits. Nonassociative factors, such as sensitivity to the stimuli or general health, could not account for these differences. Data are discussed in terms of using retention of the conditioned eyeblink response as a model system for studying age-related memory deficits.

Aging↗

PubMed1989

Conditioned orienting (alpha) and delayed behavioral and evoked neural responses during classical conditioning.

A differentiation of short-latency (alpha) and long-latency (delayed) classically conditioned behavioral and evoked neural (hippocampal) responses was attempted. Further, facilitation and retardation of these responses were studied in an experimental design in which 10 paired conditioning sessions either preceded (CC-CO group) or followed (CO-CC group) 10 randomly unpaired presentations of conditioned stimuli (CS) and unconditioned stimuli (UCS). A 2024-ms tone (1000 Hz) was delivered directly through a miniature earphone to the left ear, eliciting an orienting head movement ('alpha' response) to the left. The unconditioned stimulus (UCS) was a direct 1024-ms stimulation of the lateral hypothalamic area overlapping the CS (delayed paradigm) so that both stimuli terminated simultaneously. The UCS elicited approach behavior and a specific head movement in each animal. The latency and the direction of the head movement were used as criteria for a differentiation of the short-latency and long-latency conditioned responses (CR). All cats showed conditioned short-latency responses. Pairing specific long-latency head movements were observed in 10 of 13 cats and 6 of them showed a long-latency CR which was a head movement to the right, while the short-latency CR on the same trials was a head movement to the left. Hippocampal (subiculum, dentate fascia and CA1) evoked responses also showed pairing specific CRs appearing as increased negativity (short-latency CR), or increased positivity (long-latency CR). Additional reversed stimulus order (backward) sessions supported an assumption of the different nature of the short-latency and long-latency CRs: the long-latency CRs showed extinction while the short-latency CRs remained. The unpaired pre-exposure to the CSs and UCSs in the CO-CC group resulted in the retarded acquisition of the behavioral responses during the subsequent paired sessions.

Animals↗

PubMed1988

Classical conditioning alters the efficacy of identified gill motor neurones in producing gill withdrawal movements in Aplysia.

In a semi-intact preparation of Aplysia californica Cooper, classical conditioning training leads to changes in the synaptic strength at the sensory-motor neurone synapse. However, these changes are neither necessary nor sufficient to bring about the observed behavioural changes of the gill withdrawal reflex. We therefore tested whether the ability of a gill motor neurone to elicit a gill withdrawal response was altered following classical conditioning training of the reflex. We found that following classical conditioning training, the ability of a gill motor neurone to elicit a gill withdrawal response was significantly potentiated. In addition, in control preparations which did not receive classical conditioning training, the ability of a gill motor neurone to elicit a gill response was decreased. Thus, associative learning of this reflex appears to involve alteration in neuronal activity at loci distal to the sensory-motor neurone synapse.

Animals↗

PubMed1987

Increase in [3H]glutamate release from slices of dentate gyrus and hippocampus following classical conditioning in the rat.

The release of amino acids was examined in three hippocampal areas following classical conditioning. Paired or unpaired tone(CS)-shock(US) presentations were given to animals engaged in a previously acquired food-motivated lever-pressing task. Conditioned suppression of lever-pressing was the behavioural measure of conditioning. The dentate gyrus and areas CA1 and CA3 of the hippocampus were removed bilaterally from conditioned and pseudoconditioned animals, and slices cut and stored in liquid nitrogen for subsequent in vitro analysis of the release of radiolabelled glutamate and aspartate. K+-stimulated release of radiolabelled amino acids was analysed in the presence and absence of extracellular Ca2+. Potassium-stimulated, Ca2+-dependent release of [3H]glutamate was significantly greater in slices of dentate gyrus and area CA1 prepared from conditioned animals than from pseudoconditioned animals. This finding identifies a neurochemical change associated with classical conditioning which is similar to the increase in transmitter release seen in hippocampal long-term potentiation (LTP), and which is consistent with the hypothesis that an LTP-like mechanism is involved in mnemonic processes.

Animals↗

PubMed2000

Eyeblink classical conditioning: hippocampal formation is for neutral stimulus associations as cerebellum is for association-response.

Extensive evidence has been amassed that the cerebellum, hippocampus, and associated circuitry are activated during classical conditioning of the nictitating membrane/eyeblink response. In this article, the authors argue that the cerebellum is essential to all eyeblink classical conditioning paradigms. In addition, the septohippocampal system plays a critical role when the classical conditioning paradigm requires the formation of associations in addition to the simple association between the conditioned and unconditioned stimuli. When only a simple conditioned stimulus--unconditioned stimulus association is needed, the septohippocampal system has a more limited, modulatory role. The neutral stimulus association versus simple association-response distinction is one of the ways in which declarative or relational memory can be separated from nondeclarative or nonrelational memory in classical conditioning paradigms.

Blinking↗

PubMed1996

Effects of early cerebellar removal on the classically conditioned bradycardia of adult rabbits.

The magnitude of classically conditioned bradycardia was studied in 18-day-old and adult rabbits in which the cerebellar vermis had been surgically removed on either the 5th or 18th postnatal day. In the conditioning procedure, an auditory stimulus (5 s, 1000 Hz) served as conditioned stimulus (CS) and a train of electric impulses applied to the ear (100 Hz, 500 ms, 1.5 mA) was employed as the unconditioned stimulus (US). Heart rate (HR) responses developed in the operated animals during the CS-alone (orientation), and CS-US paired presentations (conditioning) were analyzed and compared with those developed in control animals. In all the experimental groups, lesions were localized to the cortex of lobules IV-VII and the underlying white matter, sparing the deep cerebellar nuclei. None of the lesioned animals showed any behavioral or somatomotor deficit. All the operated animals exhibited a normal baseline HR and a marked orienting response, both comparable with those of controls. In contrast, while the animals tested at 18 days showed a normal pattern of conditioned bradycardia, at the age of 3 months the HR conditioned response differed significantly from that observed in control rabbits: the animals that received the earliest cerebellar lesion showed a conditioned bradycardia greater than that of controls, the rabbits lesioned on the 18th postnatal day exhibited a reduced bradycardic response. These results suggest that the timing of cerebellar vermis removal, at early stages of development, represents a crucial factor in the organization of the bradycardic response in the adult.

Acoustic Stimulation↗

PubMed2003

Long-term retention of the classically conditioned eyeblink response in rats.

Retention of the classically conditioned eyeblink response in rats was tested with a conditioned stimulus (CS)-alone extinction test and 2 sessions of reacquisition training. Retention of the eyeblink conditioned response (CR) during both tests was highest 24 hr and 1 month after initial acquisition. Three months after initial acquisition, responding during the CS-alone test was at baseline, but there was significant savings during reacquisition. By 6 months after initial acquisition, the memory for the eyeblink CR was not expressed in either test. The group differences in retention, despite initial acquisition of the eyeblink CR to equal levels, suggest that rat eyeblink conditioning may provide a useful behavioral model for studying the neural processes underlying memory retention and loss.

Animals↗

PubMed2001

Dorsal hippocampal lesions impair appetitive classical conditioning to localized cues.

Three experiments examined appetitive classical conditioning in rats with small electrolytic lesions of the dorsal hippocampus. In all the experiments, the reinforcer was food delivery and the conditioned response (CR) entry to the food tray; the three experiments differed in the nature of the conditioned stimulus (CS). When this was a small light located inside the food tray, conditioning was impaired in lesioned animals, but when the CS was a general increase in illumination, they learned at the same rate as controls. With a white noise as the CS, learning was significantly faster in lesioned subjects. These data demonstrate that lesions of the dorsal hippocampus can produce impairments in appetitive delay conditioning, but only with certain types of CS. It is suggested that deficits are found with CSs that are localized in space.

Animals↗

PubMed1998

Classical conditioning and brain systems: the role of awareness.

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.

Aged↗

PubMed1986

Effects of morphine, ethylketocyclazocine, and N-allylnormetazocine on classical conditioning of the rabbit nictitating membrane response.

The rabbit's nictitating membrane response was classically conditioned to tone and light conditioned stimuli presented for 800 ms before delivery of a 100-ms unconditioned shock stimulus. Both the mu receptor agonist morphine (5 mg/kg) and the kappa receptor agonist ethylketocyclazocine (1 mg/kg) significantly retarded the acquisition of conditioned responses (CRs). The retardant effects of both morphine and ethylketocyclazocine on CR acquisition could still be detected when the rabbits were tested 5 days after cessation of drug injections. At the dose employed in this study (5 mg/kg), the sigma receptor agonist N-allylnormetazocine had no effect on acquisition. The retardant effects of morphine and ethylketocyclazocine on acquisition were significantly antagonized by both naloxone (1 mg/kg) and N-allylnormetazocine (5 mg/kg). It was suggested that mu and possibly kappa receptors are involved in the retardant effects of opiates on the acquisition of classically conditioned responses.

Animals↗

PubMed1995

The cellular basis of classical conditioning in Aplysia californica--it's less simple than you think.

Classical conditioning of the withdrawal reflex of the marine snail Aplysia californica can be used as an important model system for investigating the neurobiology of associative learning. It results when weak tactile stimulation of the snail's mantle shelf or siphon is repeatedly paired with strong electrical shocks to the animal's tail. This learned behavioral change is thought to be mediated by a presynaptic neuronal mechanism-activity-dependent presynaptic facilitation of the connections between sensory and motor neurons in the CNS of Aplysia. Recent evidence suggests, however, that another type of synaptic plasticity-Hebbian potentiation of the sensorimotor connections-might contribute to classical conditioning in Aplysia. Additional evidence indicates that this relatively simple form of learning is likely to be mediated by multiple neuronal mechanisms.

Animals↗

PubMed2003

In vitro classical conditioning of the turtle eyeblink reflex: approaching cellular mechanisms of acquisition.

The classically conditioned eyeblink reflex is the best studied model for understanding the neural mechanisms that underlie learning and memory. Here, data from an in vitro model of the conditioned eyeblink reflex are summarized with the aim of shedding some light on potential cellular mechanisms that may underlie eyeblink classical conditioning. An isolated brainstem-cerebellum preparation from turtles was developed in which to study the synaptic circuitry of pathways involving the cerebellum, red nucleus and brainstem nuclei. A neural correlate of an eyeblink response recorded in the abducens nerve can be conditioned entirely in vitro by pairing trigeminal and auditory nerve stimulation. Conditioned abducens nerve responses (CRs) are not generated or sustained by unpaired stimuli and their long latencies, on the order of hundreds of milliseconds, support the interpretation that the CRs are not unconditioned responses. Ablation experiments show that CRs can be generated in brainstem preparations lacking a cerebellum or the medulla. However, the timing of the CRs are disrupted by removal of the cerebellar circuitry. Thus, a highly reduced in vitro brainstem preparation demonstrates acquisition of CRs but poor timing features. Recent experiments have focused on elucidating cellular mechanisms for CR acquisition in the brainstem blink circuitry. These studies show that NMDA-mediated synaptic mechanisms are required to generate CRs and that the level of conditioning is associated with the upregulation of GluR4-containing AMPA receptors in the abducens motor nuclei. Data from immunocytochemistry and physiological experiments using the calcium/calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-93 suggest that CaMKII does not have a key role in mediating the induction or expression of abducens nerve CRs. It is hypothesized that GluR4-containing AMPA receptors in the abducens motor nuclei are targeted to auditory nerve synapses by an NMDA receptor-dependent process to strengthen the CS input during conditioning which results in the generation of CRs. Future studies will examine the synaptic localization of GluR4 and potential signal transduction pathways involved in in vitro conditioning. Moreover, the role feedback loops through the cerebellum and their role in CR timing will be a key issue to address using this preparation.

Animals↗

PubMed2004

Targeting of GLUR4-containing AMPA receptors to synaptic sites during in vitro classical conditioning.

The synaptic delivery of GluR4-containing AMPA receptors during in vitro classical conditioning of a neural correlate of an eyeblink response was examined by fluorescence imaging of punctate staining for glutamate receptor subunits and the presynaptic marker synaptophysin. There was a significant increase in GluR4-containing AMPA receptors to synaptic sites after conditioning as determined by colocalization of GluR4 subunit puncta with synaptophysin. Moreover, the trafficking of these receptor subunits requires NMDA receptor activation as it was blocked by D,L-2-amino-5-phosphonovaleric acid (AP-5). In contrast, colocalization of NR1 subunits with synaptophysin was stable regardless of whether the preparations had undergone conditioning or had been treated by AP-5. The enhanced colocalization of GluR4 and synaptophysin was accompanied by an increase in both the total number and size of puncta for both proteins, suggesting greater synthesis and aggregation during conditioning. Western blot analysis confirmed upregulation of synaptophysin and GluR4 following conditioning. These data support the hypothesis that GluR4-containing AMPA receptors are delivered to synaptic sites during conditioning. Further, they suggest coordinate presynaptic and postsynaptic modifications during in vitro classical conditioning.

2-Amino-5-phosphonovalerate↗

PubMed1997

The cerebellum and red nucleus are not required for In vitro classical conditioning of the turtle abducens nerve response.

The role of the cerebellum during motor learning is a controversial issue. Many authors have suggested that the cerebellum and its connections with the red nucleus are essential for the acquisition of the conditioned eye blink reflex. Although there is little argument that the cerebellum is an important component to the generation of the conditioned response (CR), a number of studies have suggested that the cerebellum is not essential for conditioning. Using an in vitro model of the classically conditioned turtle abducens nerve response, we investigated the effect of cerebellar and red nucleus lesions on the acquisition, extinction, and reacquisition of CRs. Neural discharge was recorded from the abducens nerve after a single shock unconditioned stimulus (US) was applied to the ipsilateral trigeminal nerve. When the US was paired with a conditioned stimulus (CS) applied to the posterior eighth, or auditory, nerve, a positive slope of CR acquisition was recorded in the abducens nerve. After extinction stimuli in which the CS and US were alternated, the number of CRs decreased to near zero. When the CS and US were once again paired, reacquisition at a faster rate was recorded. The CRs showed unusual timing features compared with preparations in which the cerebellum was intact; they had significantly shorter latencies and showed burst-like responses. These data demonstrate that it is possible to classically condition this in vitro preparation in the absence of the cerebellum and red nucleus. However, the latencies of CRs were found to be dramatically altered in the cerebellar-lesioned preparations, suggesting that the cerebellum does play a role in the timing of the CR.

Abducens Nerve↗

PubMed2003

Video recording system for the measurement of eyelid movements during classical conditioning of the eyeblink response in the rabbit.

Classical conditioning of the eyeblink response in the rabbit is a popular model for studying the neural substrates of associative learning. Most of the common eyeblink recording techniques require invasive procedures. To perform experiments in intact animals, a non-invasive, high-speed video recording system was developed to measure eyeblink responses of rabbits during classical conditioning experiments. Besides being non-invasive, this method does not require excessive restraint of the animal. The PC-based system combines a Pulnix video camera with National Instruments video capture and timing hardware to control the experiment and acquire images of the peri-ocular region. The software developed for controlling these experiments also detects the eyeblink by measuring the movement of the upper and lower eyelids, the area of the exposed surface of the eye, and head movements in the sagittal plane. The time resolution of this relatively inexpensive system is 8.33 ms, and at a working distance of 0.8 m, it can detect movements as small as 0.11 mm.

Animals↗

PubMed1982

Classical conditioning of front paw and hind paw footshock induced analgesia (FSIA): naloxone reversibility and descending pathways.

Opiate and non-opiate footshock induced analgesia (FSIA) has recently been observed to be differentially elicited dependent upon the body region shocked; front paw and hind paw shock produce opiate and non-opiate analgesia, respectively. Previous studies have shown that footshock can also produce classically conditioned analgesia; that is, when shock is delivered to an animal, environmental cues become associated with the noxious stimulus such that these cues become capable, in and of themselves, of producing potent analgesia. The present series of experiments examined analgesia classically conditioned to either front paw or hind paw shock. The non-electrified shock grid served as the conditioned stimulus (CS), 90-s footshock as the unconditioned stimulus (UCS) and tail-flick inhibition as the unconditioned response (UCR). Following CS-UCS pairings, exposure to the non-electrified grid reliably produced prolonged analgesia. This classically conditioned analgesia appears to involve endogenous opioids, regardless of the body region shocked during conditioning trials, since the analgesia is attenuated by systemic naloxone and shows cross-tolerance to morphine. A spinal opioid site is involved since 1 microgram of naloxone delivered directly to the lumbosacral cord antagonizes the analgesia. Like front paw (opiate) FSIA, CCA can be prevented but cannot be reversed by naloxone; naloxone can antagonize classically conditioned analgesia only if it is delivered prior to exposure to the conditioned stimulus. Lastly, a similarity was recognized between classically conditioned analgesia and the analgesia induced by morphine, brain stimulation, front paw shock and hind paw shock in that all are mediated via descending pathways within the dorsolateral funiculus of the spinal cord.

Analgesia↗