Integrative physiological and behavioral science : the official journal of the Pavlovian Society最新文献

We investigated the effect of prior acute stress on colonic permeability induced by a chemical irritant known to induce symptoms similar to inflammatory bowel disease in rodents. Adult male rats (n = 12) were stressed by a single session of ten unpredictable, uncontrollable foot shocks, and half were home cage controls (n = 12). Twenty-nine days later, half of each treatment group was exposed to 4% DSS (dextran sulphate sodium) solution in their drinking water for 48 hours while half received pure water over two periods separated by 17 days. After food deprivation overnight and light isoflurane anaesthesia the following morning, the animals were given a colonic infusion of 2000 nCi (nanocurie) 51CrEDTA (51Cr-labelled ethylenediaminetetraacetic acid) and then placed individually in metabolic cages for a six hours continuous urine collection. Radioactivity in urine was measured by a gamma counter and percentage recovery of 51CrEDTA calculated as an indicator of colonic mucosal permeability. Results concluded that pre-shocked animals exposed to DSS showed significantly higher mucosal permeability than the pre-shocked animals given water, and the non-shocked animals given either DSS or water. Pre-shock in combination with two exposures to a chemical irritant separated by 17 days had a pronounced effect on colonic permeability, indicating that stress should be considered a possible initiating or contributory factor to increased intestinal permeability related to a mucosal challenge.

Using a classical eyeblink conditioning paradigm, we have previously shown that the rate of acquisition of a conditioned response may be manipulated by engaging subjects in background tasks of varying complexity concurrent to conditioning. To further examine the influence of the background environment on conditioning, a picture set designed to elicit emotional responses, the International Affective Picture System (IAPS), was presented to subjects during classical eyeblink conditioning. The results suggest that eyeblink conditioning does appear to be sensitive to contextual manipulations of arousal. Pictures rated as very arousing were found to engage subjects enough to enhance learning, although not to the point that autonomic functions were significantly altered between picture groups. We suggest that group differences in learning may be a result of either novelty of, or vigilance to, interesting pictures rather than as a direct result of physiological arousal.

We have shown previously that phenytoin impairs learning in rats in several different behavioral paradigms (Churchill et al., 1998, 2003; Banks et al., 1999). The present study has examined this drug's effects on performance in a delayed match-to-place water maze paradigm developed by Steele and Morris (1999). We find that phenytoin retards performance, but only when the inter-trial interval (ITI) is short (i.e., 15-sec). With longer ITIs (i.e., 20-min, 2-hr), the performance of the phenytoin-treated rats was quite comparable to the controls. We suggest that this pattern of results stems from a disruption of spatial working memory, perhaps due to the effects of the drug on hippocampal function (cf., Churchill et al., 1998, 2003). This disruption is, however, not so profound that consolidation is prevented.

Objective: The aim of the present study was to compare autonomic activity, pressure-pain thresholds, and subjective assessments of health and behavior between patients with stress-related illnesses and healthy control subjects.

Methods: Twenty sick-listed patients with stress-related illnesses and 20 age- and gender-matched healthy subjects performed tests of autonomic regulation and algometric tests, and completed questionnaires about physical and mental health and behavioral patterns.

Results: Patients exhibited higher autonomic reactivity to cognitive and physical laboratory tasks (p < 0.05), and had lower pressure-pain thresholds in the shoulders and lower back than healthy control subjects (p < 0.05). Furthermore, the patients rated considerably poorer health and health behavior than the control subjects (p < 0.05).

Conclusions: The results indicate an engagement of the autonomic nervous system in stress-related illnesses. Furthermore, they show that patients with stress-related illnesses experience symptoms of musculoskeletal pain, and it is therefore recommended that assessments of musculoskeletal pain be incorporated in the clinical examinations and the rehabilitation of patients with stress-related illnesses.

Recent research has found that people with Irritable Bowel Syndrome (IBS) and those with Inflammatory Bowel Disease (IBD) show a relative deficit in verbal IQ, compared to their own performance IQ, and the IQ of a healthy comparison group. It has been suggested that the elevated prevalence of left-handedness shown in previous studies investigating people with IBD is due to compromised left-hemisphere development. This may be associated with a decrement in certain cognitive functions such as verbal IQ. A shift in brain dominance from left to right has been found in many atopic and immunological diseases as well as in autonomic dysfunctions. It was uncertain whether this would apply to people with IBS, a functional disorder in which the cause or causes remain unclear. Therefore, the aim of this preliminary study was to investigate whether people with IBS have an increased prevalence of left-handedness. It was found that there was an association between IBS and left-handedness, showing that further research on this association both in IBS and other functional disorders (as well as on the similarities between IBS and IBD) is warranted.

In addition to their well-known role in neural development, the neurotrophins BDNF and NGF help mediate the plasticity that occurs in the brain to promote learning. Exposure to learning procedures often leads to increases in neurotrophins, while exposure to stress often results in decreases. It is unclear how the neurotrophins would respond to an aversive learning task. Therefore, BDNF and NGF content in the dorsal striatum, hippocampus, and basal forebrain was measured following discrete trial lever-press escape/avoidance conditioning. Conditioning significantly increased levels of both neurotrophins in hippocampus and basal forebrain, relative to home cage controls (HCC). Contrary to expectations, the dorsal striatum did not show any significant changes. However, significant correlations were observed between dorsal striatal neurotrophins and aspects of avoidance performance. This may indicate that the dorsal striatum is involved in the performance aspects of the task. Results are discussed in terms of the role of neurotrophins in the acquisition of new information, and the neural structures involved in different types of memory.

Research on consolidation of long-term memory suggests that acute immune system activation induced by endotoxin lipopolysaccharide (LPS) may disrupt consolidation of newly acquired learning. Adult male Sprague-Dawley rats were trained to perform a simple Y-maze task and were immediately afterwards administered LPS (15 microg/kg) or saline. After a seven-day interval, subjects were returned to the Y-maze and were retrained to criterion. It was found that subjects treated with saline required significantly fewer trials to relearn the task relative to the LPS group and a no-partial-learning control group, which themselves did not differ. These results are most readily explained in terms of a disruptive effect of acute immune system activation on consolidation of newly induced acquired memories.

This article presents a brief description of the scientific discovery of classical conditioning both in the United States and in Russia. The incorporation of classical conditioning as a scientific method in the United States is described. Particular attention is given to how and why the terminologies used to identify the components of classical conditioning were modified over the years. I then trace the curious evolution of the terminology associated with Pavlov's form of conditioning, from its introduction to the United States as "the Pawlow salivary reflex method" to its present appellation as classical conditioning. Finally I conclude by developing a theory as to when and why the term classical conditioning was adopted.

In classical eyeblink conditioning, non-specific emotional responses to the aversive shock unconditioned stimulus (US), which are presumed to coincide with the development of fear, occur early in conditioning and precede the emergence of eyeblink responses. This two-process learning model was examined by concurrently measuring fear and eyeblink conditioning in the freely moving rat. Freezing served as an index of fear in animals and was measured during the inter-trial intervals in the training context and during a tone conditioned stimulus (CS) presented in a novel context. Animals that received CS-US pairings exhibited elevated levels of fear to the context and CS early in training that decreased over sessions, while eyeblink conditioned responses (CRs) developed gradually during acquisition and decreased during extinction. Random CS-US presentations produced a similar pattern of fear responses to the context and CS as paired presentations despite low eyeblink CR percentages, indicating that fear responding was decreased independent of high levels of learned eyeblink responding. The results of paired training were consistent with two-process models of conditioning that postulate that early emotional responding facilitates subsequent motor learning, but measures from random control animals demonstrate that partial CS-US contingencies produce decrements in fear despite low levels of eyeblink CRs. These findings suggest a relationship between CS-US contingency and fear levels during eyeblink conditioning, and may serve to clarify further the role that fear conditioning plays in this simple paradigm.

Defensive responses to a cat were observed in rats given excitotoxic lesions of the central nucleus of the amygdala (ACe), dorsolateral periaqueductal gray (dlPAG), ventral periaqueductal gray (vPAG), or sham lesions. Rats were placed adjacent to a compartment containing a cat. Sham-lesioned rats avoided the area nearest the cat and preferred the area furthest away from the cat. They also exhibited numerous defensive responses including, climbing, escape from the apparatus, and freezing. Rats with lesions of the ACe reacted like the sham lesioned rats by preferring the area of the apparatus furthest from the cat, however they climbed and escaped significantly less than sham lesioned rats. Avoidance of the area adjacent to the cat was attenuated in rats with lesions of the vPAG. Climbing along the walls of the apparatus was also attenuated in rats with lesions of the vPAG. Escapes from the apparatus were not significantly reduced by lesions of the vPAG and dlPAG. Thus, ACe lesions attenuated climbing and eliminated escapes, but did not impair locomotion of the rat away from the cat.