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At least 865 records · Page 48Linked to original sources

PubMed2004

Cholecystokinin tetrapeptide improves water maze performance of neonatally 6-hydroxydopamine-lesioned young rats.

This study addressed the proposed memory-modulating effect of the cholecystokinin (CCK) 2 agonist Boc-CCK-4 in rats using a Morris water maze. In the brain, CCK is colocalized and interacts with dopamine, respectively. To impair dopaminergic neurotransmission, and consequently, dopamine-mediated learning and memory, rat pups received the neurotoxin 6-hydroxydopamine (6-OHDA) into the left [Day 5 postnatal (p.n.)] and right (Day 8 p.n.) ventricles (50 microg/5 microl each). After 6-OHDA treatment, dopamine brain levels were reduced by 60% on Day 50 p.n. Lesioned rats had a lower body weight but normal swimming abilities. In the acquisition phase of the water maze (Day 50 p.n.), sham-lesioned rats learned quickly, compared to lesioned rats. Treatment with Boc-CCK-4 (40 microg/kg ip) did not affect performance in sham-lesioned rats but restored the learning curve in lesioned rats without increasing swimming speed indicating a better spatial learning in the dopamine-depleted rats. In summary, these findings demonstrate that stimulation of CCK2 receptors may counteract cognitive deficits of dopamine-depleted rats.

Animals↗

PubMed2003

CT colonography: methods, pathology and pitfalls.

Computed tomography colonography (CTC) is a relatively new technique that is currently challenging more established methods of large bowel imaging. Several workers have suggested CTC surpasses the barium enema and approaches conventional endoscopy for detection of colorectal neoplasia. Accurate diagnosis relies on technically good studies, the main aim of which is adequate bowel cleansing and distension. Furthermore, the learning curve is steep and normal colonic anatomy has to be re-learned in a CT context. This review aims to describe the technique, revise the imaging features of both normal and pathological colon, and to highlight potential diagnostic pitfalls and their avoidance.

Colitis↗

PubMed1991

Conditional withholding of proboscis extension in honeybees (Apis mellifera) during discriminative punishment.

Proboscis extension conditioning of honeybee workers was used to test the ability of bees to respond to appetitive and aversive stimuli while restrained in a harness that allows subjects to move their antennae and mouthparts (Kuwabara, 1957; Menzel, Erber, & Masuhr, 1974). Subjects were conditioned to discriminate between two odors, one associated with sucrose feeding and the other associated with a 10 V AC shock if they responded to the sucrose unconditioned stimulus (US) in the context of that odor. Most Ss readily learned to respond to the odor followed by sucrose feeding and not to the odor associated with sucrose stimulation plus shock. Furthermore, in the context of the odor associated with shock, significantly more subjects withheld or delayed proboscis extension on stimulation with the sucrose US than they did in the context of the odor associated with feeding. Thus, restrained honeybees can readily learn to avoid shock according to an odor context by withholding proboscis extension to a normally powerful releaser. Analysis of individual learning curves revealed that subjects differed markedly in performance on this task. Some learn the discrimination quickly, whereas others show different kinds of response patterns.

Animals↗

PubMed1981

Individual recognition and learning of queen odors by worker honeybees.

A honeybee queen is usually attacked if she is placed among the workers of a colony other than her own. This rejection occurs even if environmental sources of odor, such as food, water, and genetic origin of the workers, are kept constant in laboratory conditions. The genetic similarity of queens determines how similar their recognition characteristics are; inbred sister queens were accepted in 35% of exchanges, outbred sister queens in 12%, and nonsister queens in 0%. Carbon dioxide narcosis results in worker honeybees accepting nonnestmate queens. A learning curve is presented, showing the time after narcosis required by workers to learn to recognize a new queen. In contrast, worker transfers result in only a small percentage of the workers being rejected. The reason for the difference between queens and workers may be because of worker and queen recognition cues having different sources.

Journal Article↗

PubMed2003

Mnemonic strategies in older people: a comparison of errorless and errorful learning.

OBJECTIVE: To compare the efficacy of errorless and errorful learning on memory performance in older people and young adults. METHODS: Face-name association learning was examined in 18 older people and 16 young controls. Subjects were either prompted to guess the correct name during the presentation of photographs of unknown faces (errorful learning) or were instructed to study the face without guessing (errorless learning). The correct name was given after the presentation of each face in both task conditions. Uncued testing followed immediately after the two study phases and after a 10-minute delay. RESULTS: Older subjects had an overall lower memory performance and flatter learning curves compared to the young adults, regardless of task conditions. Also, errorless learning resulted in a higher accuracy than errorful learning, to an equal amount in both groups. CONCLUSIONS: Older people have difficulty in the encoding stages of face-name association learning, whereas retrieval is relatively unaffected. In addition, the prevention of errors occurring during learning results in a better memory performance, and is perhaps an effective strategy for coping with age-related memory decrement.

Adult↗

PubMed2004

Motor skill learning depends on protein synthesis in motor cortex after training.

The role of protein synthesis in memory consolidation is well established for hippocampus-dependent learning and synaptic plasticity. Whether protein synthesis is required for motor skill learning is unknown. We hypothesized that skill learning is interrupted by protein synthesis inhibition (PSI). We intended to test whether local protein synthesis in motor cortex or cerebellum is required during skill acquisition and consolidation. Anisomycin (ANI; 100 microg/microl in 1 microl of PBS) injected into motor cortex, posterior parietal cortex, or cerebellum produced 84.0 +/- 1.44% (mean +/- SEM), 85.9 +/- 2.31%, and 87.3 +/- 0.17% of PSI 60 min after administration, respectively. In motor cortex, protein synthesis was still reduced at 24 hr (72.0 +/- 4.68% PSI) but normalized at 48 hr after a second injection given 24 hr after the first. To test for the effects of PSI on learning of a skilled reaching task, ANI was injected into motor cortex contralateral to the trained limb or into ipsilateral cerebellum immediately after daily training sessions 1 and 2. Two control groups received motor cortex injections of vehicle or ANI injections into contralateral parietal cortex. Control and cerebellar animals showed a sigmoid learning curve, which plateaued after day 4. PSI in motor cortex significantly reduced learning during days 1-4. Thereafter, when protein synthesis normalized, learning was reinitiated. ANI injections into motor cortex did not induce a motor deficit, because animals injected during the performance plateau did not deteriorate. This demonstrates that motor skill learning depends on de novo synthesis of proteins in motor cortex after training.

Animals↗

PubMed2026

Individual Differences in Cognitive Aging Rodent Datasets (ID-CARD): A collaborative platform for behavioral analysis across the lifespan.

Understanding cognitive aging requires approaches that capture individual variability while enabling integration across studies. In rodent models, behavioral data are central to this effort, yet cross-laboratory differences in experimental design limit comparability and constrain secondary analysis. To address this gap, we developed the Individual Differences in Cognitive Aging Rodent Datasets (ID-CARD), a first-of-its-kind collaborative repository aggregating trial-level Morris water maze data from multiple laboratories. ID-CARD is designed to support large-scale, integrative analyses and to facilitate secondary use of existing behavioral data in alignment with emerging data-sharing and transparency initiatives. Rather than imposing retrospective harmonization of experimental protocols, we implemented a normalization and modeling framework that enables comparison of learning trajectories while preserving meaningful variation across studies. Behavioral data from > 5000 rats spanning common strains, both sexes, and multiple ages were normalized in training and performance domains and fit with a logarithmic function to derive an error accumulation rate coefficient (EARC) as a measure of spatial learning. Age was strongly associated with increased EARC, indicating attenuated learning, even after adjusting for non-spatial cue performance. Analyses of goodness of fit revealed systematic structure in learning dynamics, where age was associated with reduced learning-curve conformity after accounting for overall performance. Inter-individual variability in spatial learning also increased with age, with strain-specific interactions. These findings demonstrate that integrated analysis of heterogeneous behavioral datasets can yield robust, individual-level insights into cognitive aging. ID-CARD provides a scalable resource and analytic framework to advance discovery in behavioral neuroscience by enabling reuse, integration, and comparative analysis of existing data.

Cognitive aging↗

PubMed2001

Time scales in motor learning and development.

A theoretical framework based on the concepts and tools of nonlinear dynamical systems is advanced to account for both the persistent and transitory changes traditionally shown for the learning and development of motor skills. The multiple time scales of change in task outcome over time are interpreted as originating from the system's trajectory on an evolving attractor landscape. Different bifurcations between attractor organizations and transient phenomena can lead to exponential, power law, or S-shaped learning curves. This unified dynamical account of the functions and time scales in motor learning and development offers several new hypotheses for future research on the nature of change in learning theory.

Cognition↗

PubMed1970

Prolonged learning and split-brain cats.

A definite relation is shown between interhemispheric transfer and speed of learning. Split-brain cats were trained in a variety of discriminations, and the success or failure of interhemispheric transfer was evaluated with regard to rate of learning. When interhemispheric transfer succeeds, learning time is normal; when interhemispheric transfer fails, learning time is prolonged, becoming at least twice that of normal. Retention is also poor in those animals that exhibit prolonged learning. A normal learning curve appears to be the product of interaction between both cerebral hemispheres during learning.

Animals↗

PubMed2003

A dietary supplement abolishes age-related cognitive decline in transgenic mice expressing elevated free radical processes.

We previously found that transgenic mice overexpressing growth hormone (TGM) have elevated and progressively increasing free radical processes in brain that strongly correlates with reduced survivorship. Young mature TGM, however, displayed vastly enhanced learning of an eight-choice cued maze and qualitatively different learning curves than normal controls. Here we document the age-related patterns in learning ability of TGM and normal mice. Learning appeared inferior in both genotypes of very young mice but TGM were confirmed to be superior to normal mice upon maturity. Older TGM, however, showed rapid age-related loss of their exceptional learning, whereas normal mice at 1 year of age showed little change. The cognitive decline of TGM was abolished by a complex "anti-aging" dietary supplement formulated to promote membrane and mitochondrial integrity, increase insulin sensitivity, reduce reactive oxygen and nitrogen species, and ameliorate inflammation. Results are discussed in the context of reactive oxygen and nitrogen species, long-term potentiation, learning, aging and neuropathology, based on known impacts of the growth hormone axis on the brain, and characteristics of TGM.

Aging↗

PubMed1996

Disruption of learning by excitatory amino acid receptor antagonists.

Compounds that act as competitive or uncompetitive N-methyl-D-aspartate (NMDA) antagonists, glycine/NMDA-site antagonists, or alpha-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxalzolepropionic acid (AMPA)-receptor antagonists were evaluated for effects on a repeated acquisition of behavioral chains schedule by rats. Responding by rats was maintained by food presentation under a repeated acquisition or a performance procedure. Under the repeated acquisition procedure, subjects acquired a different three-response chain each daily session. Thus, each day a new learning curve could be generated for each animal thereby providing a repeated measure of learning. Food was presented under a second-order fixed-ratio three (FR3) schedule. Under the performance schedule rats responded under the same second-order FR3 schedule of food presentation: however, instead of a new sequence being presented each day, the same sequence of responding was required for each daily session. Both the competitive (CGS 19755) and uncompetitive (dizocilpine) NMDA antagonists distrupted repeated acquisition at doses that did not disrupt performance. In contrast, the glycine/NMDA antagonist MDL 104,653 or the competitive AMPA receptor antagonist LY 293558 did not disrupt acquisition or performance up to doses that suppressed responding. These results suggest there are different roles for various excitatory amino acid receptors, or sites on the NMDA receptor, in the neural bases of learning and that the disruption of acquisition by glutamate antagonists is dependent upon the particular receptor at which they have activity as well as the particular modulatory site of action.

Journal Article↗

PubMed2006

The modified Location Learning Test: norms for the assessment of spatial memory function in neuropsychological patients.

This study examines the applicability of the modified Location Learning Test (mLLT) as a test of spatial memory in neuropsychological patients. Three groups of participants were examined: stroke patients, patients with diabetes mellitus and healthy participants (N=411). Three error measures were computed, the Total Score (index of overall performance), the Learning Index (the learning curve over subsequent trials) and the Delayed Recall Score, measuring decay over time. The Learning Index was the most sensitive measure, showing differences between the three groups as well as lateralization effects within the stroke group. Also, the mLLT correlated significantly with the Rey Auditory Verbal Learning Test, as well as with age and education level. Regression-based normative data were computed based on the healthy participants. In all, the mLLT appears to be a sensitive and valid test for the detection of object-location memory impairments in clinical groups.

Adolescent↗

PubMed2004

Cosmetic blepharoplasty.

Cosmetic blepharoplasty is the hallmark of facial rejuvenation and is rewarding for the surgeon and patient. No other cosmetic procedure is more common in the 40- to 65-year age group. This procedure carries a steep learning curve, but the training of an oral and maxillofacial surgeon is adequate to begin learning this procedure. Proper diagnosis and adherence to strict preoperative, intraoperative, and postoperative protocols are paramount to avoiding complications that may be serious. The author, like many surgeons, enjoys this procedure and believes that its place in the contemporary scope of oral and maxillofacial surgery is well established.

Adipose Tissue↗

PubMed1999

Task decomposition analysis of intertrial free recall performance on the Rey Auditory Verbal Learning Test in normal aging and Alzheimer's disease.

Task decomposition provides supplementary data that complement traditionally computed performance indexes of multi-trial list learning. Both traditional and decomposition approaches can be combined to permit a thorough assessment of multiple aspects of learning and memory in patients with memory impairment. We applied task decomposition to investigate the relative roles of acquisition and consolidation in mediating the multi-trial learning deficit in patients with Alzheimer's disease. This goal was accomplished by decomposing recall performance across the five study-and-test trials of the Rey Auditory Verbal Learning Tests into measures that presumably tap intertrial acquisition and intertrial consolidation. As compared to matched controls, patients diagnosed with mild Alzheimer's disease showed lower gained access across trials, indicating that Alzheimer's disease impairs the ability to produce a stable memory representation of new material in long-term memory. Additionally, patients with Alzheimer's disease manifested higher lost access, which suggests that deficient consolidation leading to rapid intertrial forgetting also contributes to their poor learning. We argue that analytically decomposing learning curves will help both in uncovering the cognitive processes that underlie disease-related learning deficits in persons with memory disorders and can help to characterize potential areas for remediation.

Aged↗

PubMedDate not supplied

Effects of desmopressin acetate (DDAVP) on the learning of a brightness discrimination.

Sixty male albino rats received DDAVP, a placebo, or control treatment and were tested on a brightness discrimination task. Three groups (DDAVP, placebo, and control) were tested in the morning and three groups were tested in the evening. The acquisition and reversal of the brightness discrimination, along with the retention of the reversal problem after a 5-day retention interval were analyzed. Inspection of forward and backward learning curves plotted for each task revealed facilitated acquisition along with an initial impairment of reversal learning in those animals treated with DDAVP. These results support a memorial interpretation of DDAVP's effects. This was short-term in duration, as no retention effects were obtained. It was also found that DDAVP's effects were not influenced by diurnal processes.

Adrenocorticotropic Hormone↗

PubMed2004

Characterization of motor skill and instrumental learning time scales in a skilled reaching task in rat.

Successful motor skill learning requires repetitive training interrupted by rest periods. In humans, improvement occurs within and between training sessions reflecting fast and slow components of motor learning [Karni A, Meyer G, Rey-Hipolito C, Jezzard P, Adams MM, Turner R, et al. The acquisition of skilled motor performance: fast and slow experience-driven changes in primary motor cortex. Proc Natl Acad Sci USA 1998;95:861-8]. Here, these components are characterized in male and female rats using a model of skilled forelimb reaching and are compared to time scales of instrumental learning. Twenty female and 14 male adult Long-Evans rats were pre-trained to operate a motorized door (via a sensor in the opposite cage wall) to access a food pellet by tongue. Latencies between pellet removal and door opening were recorded as measures of instrumental learning. After criterion performance was achieved, skilled forelimb reaching was requested by increasing the pellet-window distance to 1.5cm. Reaching success was recorded per trial. Mean latencies decreased exponentially over sessions and no improvement within-session was found. Skill learning over eight training sessions followed an exponential course in females and a sigmoid course in males. Females acquired the skill significantly faster than males starting at higher baseline levels (P < 0.001) but reaching similar plateaus. Within-session improvement was found during the sessions 1-3 in females and 1-4 in males. Performance at the end of session 1 was not carried over to session 2. Learning curves of individual animals were highly variable. These findings confirm in rat that motor skill learning has fast and slow components. No within-session improvement is seen in instrumental learning.

Animals↗

PubMed1992

Learning to find the opponent: an ethological analysis of the behavior of paradise fish (Macropodus opercularis) in intra- and interspecific encounters.

In Experiment 1, 15 behavior patterns of male paradise fish (Macropodus opercularis; n = 72) toward a male conspecific, a male of another species, or no stimulus were recorded, both in home and novel situations. In Experiment 2, the same behaviors were recorded in a runway, and the same stimuli were used as reinforcers in the goal box (n = 18). A typical learning curve was seen when the subject found a male paradise fish in the goal box, learning was followed by apparent extinction when another species was found in the goal box, and few signs of learning were seen when the goal box was empty. Performance of the fish in both experiments can be accounted for by a strong aggressive motivation, a less strong but clear general curiosity, and habituation to the experimental procedure. In contrast to recent assertions in the literature, we conclude that aggressive behavior clearly can serve as a reinforcer in an instrumental learning situation.

Aggression↗

PubMed1988

The impact of electronic imaging in intraoperative biliary endoscopy (choledochoscopy).

In the last decade, choledochoscopy has become an essential tool for biliary surgery. It is widely accepted, but it is not employed by every surgeon who performs choledocholithotomies. The reason is the limited experience of surgeons performing 30-40 cholecystectomies per year. A survey of 150 hospitals clearly showed that common bile duct exploration is performed in 10%-15% of these cases. General surgeons are not endoscopists. A new video choledochoscope that displays the image in a large format via the TV monitor was developed, which can be viewed with both eyes and an assistant's help; this expedites and coordinates the procedure. The entire process is videotaped and can be used for further analysis and during consultation. It has become the method of choice for teaching. Most importantly, the learning curve of general surgeons has become significantly shorter. The procedure is taught and the surgeon can learn it easily. Its use will contribute to a decrease in the incidence of retained stones and will improve patient care.

Animals↗