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PubMed1995

Possible strategies for finding the substrate for learning-induced changes in the hippocampal cortex.

For long-lasting memory traces, structural synaptic changes remain a probable mechanism. However, in higher animals it has proved difficult to provide positive evidence for this notion. The main reason may be that the changes are subtle and are to be found in a relatively small subset of synapses and in a distributed manner in the cellular network in question. Here, we discuss possible strategies for finding structural changes in the hippocampus associated with spatial learning, an activity for which this structure is important. Spatial learning may induce new excitatory synapses in a small subset of hippocampal CA1 neurons because we observe a higher spine density without alteration in dendritic length or branching. The dendritic synapses are regularly spaced, irrespective of spine density, suggesting the operation of an intersynaptic dispersing force.

Animals↗
PubMedDate not supplied

[Epilepsy and learning disorders].

INTRODUCTION: Children with epilepsy have more behavioral and cognitive problem than children with other chronic illness and children in the general population. Risk factors are multiple probably involving a combination of seizure, family and child variable, behavioral problems (depression, occur frequently but may be unrecognized). Anxiety disorders and psychoses are less common. DEVELOPMENT: The learning and behavioral found in epileptic children is multifactorial, first the effects of the conditions causing the epilepsy, in addition the epilepsy itself may cause, change in the nervous system through the metabolic and excitatory effects of the seizure and the neurotransmitter elements involved at the membrane level. The effects of the treatment modality, be it pharmacology or surgical may also play havoc with cognition function. CONCLUSION: The neurobehavioral effects of antiepileptic drug although probably less important with the newer agent than in the past, must be considered especially in polypharmacy as recent report have in dictated.

Anticonvulsants↗
PubMedDate not supplied

Cognitive-affective consequences of grading versus nongrading of formative evaluations.

In testing the effect of grading versus nongrading of formative evaluations on cognitive learning and affective behaviors of graduate nursing students the following hypotheses were formulated: The experimental (E) group will learn and demonstrate affective behaviors significantly more than control I (CI) and II (CII) groups. Subjects were 95 graduate nursing students. E group subjects (N = 38) were taught by means of FE, with grades. CI (N = 32) and CII (N = 25) groups were taught by means of lecture-discussion and FE without grades, respectively. The content covered conditions of learning and instruction in nursing. Pre- and posttests provided data on cognitive learning. Affective measures and demographic data were obtained only at the posttest. The hypotheses were tested by means of t test. Fisher's Exact Probability Test and Pearson were done to test distribution and relationships between variables. Results showed that: The E group learned significantly more than the CI group, but the CII group learned significantly more than the E group; all groups learned significantly; there were no significant differences among groups in affective behaviors although CII subjects scored highest. Implications were made for education of patients, students, and staff.

Achievement↗
PubMed2003

[Ralph Milton Waters and 75 years of professionalism in anesthesiology].

This short biography introduces Ralph Waters to Japanese speaking people. Meeting in Madison in June 2002, "Ralph Waters and Professionalism in Anesthesiology A Celebration of 75 Years", is also reported briefly. Ralph Waters is relatively unknown in Japan probably because during his professional life, Japan looked to the continental Europe to learn medicine and sent students chiefly to this area. After the end of the World War II, however, Japan sent a number of students to the United States including many who received the training in anesthesiology in the departments headed by the disciples of Waters or in the departments under the strong influence of Waters' philosophy. Therefore, it is probably true to say that Japanese anesthesiology today owes much to Waters' teaching.

Anesthesiology↗
PubMed1997

Protein sequence-structure compatibility criteria in terms of statistical hypothesis testing.

The assignment of query protein sequences to probable folds in a threading approach is based on the statistical analysis (learning) of structural properties of amino acids in known protein structures. We formalize the recognition problem in terms of mathematical statistics, namely statistical hypothesis testing. Our general formulation leads to various mathematical forms of a decision rule function for evaluation of the quality of a sequence-structure fit. Three criteria were derived according to a likelihood ratio approach. Two of them have new functional forms while the third happens to coincide with the mean force potential function previously derived under the additional assumption of the Boltzmann law. New decision rule functions employ (i) the Parzen estimator of a probability density and (ii) the newly introduced non-parametric statistic with known asymptotic distribution. We compared criteria efficiency by a 'structure seeks sequence' search for three highly populated template folds through a query library of non-homologous sequences of proteins with known 3D structure using residue accessibility as an environmental variable. Various criteria reflect different underlying statistical propositions and thus often recognize diverse correct sequence-structure matches. On the other hand, if an amino acid sequence is recognized as compatible with a template by each of three decision rules it appears that one can make a more reliable inference of sequence-structure relationship since almost all false positives obtained by the three criteria differ.

Algorithms↗
PubMedDate not supplied

[The statistical evaluation of the reliability of learning curve differences].

A nonparametric method of statistical analysis of two related binary sequences of "1" and "0" is presented. This technique enables comparison between the dynamics of probability of appearance of 1" in the two sequences. This test can be applied to the problem of statistical comparison between the dynamics of learning of a "stimulus-reaction" type when the appearance of reaction to the stimulus is labeled as "1" and its absence as "0". The graphical interpretation is given and IBM-PC/AT program is characterized which realizes the advanced method.

Animals↗
PubMed2004

Learning at a distance I. Statistical learning of non-adjacent dependencies.

In earlier work we have shown that adults, young children, and infants are capable of computing transitional probabilities among adjacent syllables in rapidly presented streams of speech, and of using these statistics to group adjacent syllables into word-like units. In the present experiments we ask whether adult learners are also capable of such computations when the only available patterns occur in non-adjacent elements. In the first experiment, we present streams of speech in which precisely the same kinds of syllable regularities occur as in our previous studies, except that the patterned relations among syllables occur between non-adjacent syllables (with an intervening syllable that is unrelated). Under these circumstances we do not obtain our previous results: learners are quite poor at acquiring regular relations among non-adjacent syllables, even when the patterns are objectively quite simple. In subsequent experiments we show that learners are, in contrast, quite capable of acquiring patterned relations among non-adjacent segments-both non-adjacent consonants (with an intervening vocalic segment that is unrelated) and non-adjacent vowels (with an intervening consonantal segment that is unrelated). Finally, we discuss why human learners display these strong differences in learning differing types of non-adjacent regularities, and we conclude by suggesting that these contrasts in learnability may account for why human languages display non-adjacent regularities of one type much more widely than non-adjacent regularities of the other type.

Adult↗
PubMed1985

Probability-reward preferences of rhesus monkeys.

The relative preferences of rhesus monkeys for reward probability versus amount were investigated with procedures which contrasted general experience with specific instructions, and evaluated the relationship between probability-amount combinations and preference strength. Four stimulus objects, each signifying a different combination of reward frequency and amount (100% with one unit; 50% with two units; 33% with three units; or 25% with four units), were presented in pairs, one pair per daily session, with trial schedules providing the same amount of reward within each set of 12 trials. In Phase A, 4 monkeys (Group 1) were tested on the six choice-pairs with no preliminary training. In Phase B, Group 1 was joined by an additional 4 monkeys (Group 2), and each of the tasks was preceded by a demonstration of the relevant stimuli, one at a time, together with their associated probabilities and amounts. Group 1 animals developed preferences during Phase A for the more frequently rewarded objects, which persisted into Phase B, whereas Group 2 animals showed no preferences. This result indicates that preliminary instructions concerning the reward combinations associated with stimulus objects can prevent the development of a preference for greater probability over greater amount of reward, but cannot extinguish it once it has been formed or reestablished within the context of a particular task.

Animals↗
PubMed1990

The primate hippocampal formation: evidence for a time-limited role in memory storage.

Clinical and experimental studies have shown that the hippocampal formation and related structures in the medial temporal lobe are important for learning and memory. Retrograde amnesia was studied prospectively in monkeys to understand the contribution of the hippocampal formation to memory function. Monkeys learned to discriminate 100 pairs of objects beginning 16, 12, 8, 4, and 2 weeks before the hippocampal formation was removed (20 different pairs at each time period). Two weeks after surgery, memory was assessed by presenting each of the 100 object pairs again for a single-choice trial. Normal monkeys exhibited forgetting; that is, they remembered recently learned objects better than objects learned many weeks earlier. Monkeys with hippocampal damage were severely impaired at remembering recently learned objects. In addition, they remembered objects learned long ago as well as normal monkeys did and significantly better than they remembered objects learned recently. These results show that the hippocampal formation is required for memory storage for only a limited period of time after learning. As time passes, its role in memory diminishes, and a more permanent memory gradually develops independently of the hippocampal formation, probably in neocortex.

Animals↗
PubMed2006

Self-controlled visual discrimination learning of group-housed dwarf goats (Capra hircus): behavioral strategies and effects of relocation on learning and memory.

In most studies on animal learning, individual animals are tested separately in a specific learning environment and with a limited number of trials per day. An alternative approach is to test animals in a familiar environment in their social group. In this study, the authors--applying a fully automated learning device--investigated voluntary, self-controlled visual shape discrimination learning of group-housed dwarf goats (Capra hircus). The majority of the tested goats showed successful shape discrimination, which indicates the adaptive value of an effective learning strategy. However, in each group, a few individual goats developed behavioral strategies different from shape discrimination to get reward. Relocation impairs memory retrieval (probably by attention shifting) only temporarily for previously learnt shapes. The results demonstrate the usefulness of a self-controlled learning paradigm to assess learning abilities of social species in their normal social settings. This may be especially relevant for captive animals to improve their welfare.

Animals↗
PubMed2006

The role of the basolateral amygdala in stimulus-reward memory and extinction memory consolidation and in subsequent conditioned cued reinstatement of cocaine seeking.

The consolidation of cue-cocaine associations and extinction learning (i.e. cue-no cocaine associations) into long-term memory probably regulates the long-lasting control of conditioned stimuli (CS) over cocaine-seeking behaviour, and the basolateral amygdala (BLA) may play a role in this phenomenon. To test this hypothesis, rats previously trained to self-administer cocaine underwent a single classical conditioning (CC) session, during which they received passive pairings of cocaine infusions and a novel light + tone stimulus complex. After additional self-administration sessions in the absence of CS presentation and subsequent extinction training sessions, the ability of the CS to reinstate cocaine-seeking on five test days was assessed. Rats received intra-BLA microinfusions of vehicle or the Na+-channel blocker tetrodotoxin (TTX) immediately after CC (consolidation of CS-cocaine associations) or immediately after reinstatement testing (consolidation of extinction learning). TTX administered immediately after CC attenuated subsequent CS-induced reinstatement. In contrast, TTX administered after the first reinstatement test impaired the extinction of cocaine-seeking behaviour during a second reinstatement test by disrupting extinction memory. Overall, these findings suggest that Na+ channel-mediated mechanisms within the BLA mediate the consolidation of both cocaine-stimulus association and extinction learning, two processes that have opposite effects on subsequent cue-induced cocaine-seeking behaviour.

Amygdala↗
PubMed1998

Kin recognition in golden hamsters: evidence for kinship odours

Differential treatment of kin and non-kin has been well documented, but much remains unclear about how kin are recognized. If kin are recognized by a phenotype-matching mechanism, there must be a correlation between genetic relatedness and the similarity of cues used for recognition. A habituation technique was used with golden hamsters, Mesocricetus auratus, to investigate the relative similarity of the odour quality of flank gland secretions from siblings and unrelated individuals. Hamsters discriminated between the odours of their own, same-sex siblings but also treated these odours as similar compared to odours of non-siblings (experiment 1). They did not discriminate between the flank gland odours of unfamiliar siblings from another family (experiment 2). They also did not discriminate between the flank gland odours of unfamiliar, paternal half-siblings from another family (experiment 3). These results indicate that subjects perceived odours from genetically similar individuals as similar and provide evidence for kinship odour cues. The discrimination between the flank gland odours of subjects' own siblings, however, indicates that hamsters learn the subtle differences between the odours of their close kin, probably through experience with siblings in the nest. When only volatile components from flank gland secretions were available to subjects (experiment 4), they again discriminated between the odours of their own siblings, suggesting that the volatile components from the flank gland secretion were sufficient for recognition of individual litter-mates. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Accidents and Decision Making under Uncertainty: A Comparison of Four Models.

Heinrich's (1931) classical study implies that most industrial accidents can be characterized as a probabilistic result of human error. The present research quantifies Heinrich's observation and compares four descriptive models of decision making in the abstracted setting. The suggested quantification utilizes signal detection theory (Green & Swets, 1966). It shows that Heinrich's observation can be described as a probabilistic signal detection task. In a controlled experiment, 90 decision makers participated in 600 trials of six safety games. Each safety game was a numerical example of the probabilistic SDT abstraction of Heinrich's proposition. Three games were designed under a frame of gain to represent perception of safe choice as costless, while the other three were designed under a frame of loss to represent perception of safe choice as costly. Probabilistic penalty for Miss was given at three different levels (1, .5, .1). The results showed that decisions tended initially to be risky and that experience led to safer behavior. As the probability of being penalized was lowered decisions became riskier and the learning process was impaired. The results support the cutoff reinforcement learning model suggested by Erev et al. (1995). The hill-climbing learning model (Busemeyer & Myung, 1992) was partially supported. Theoretical and practical implications are discussed. Copyright 1998 Academic Press.

Journal Article↗
PubMed1996

Convergence Properties of High-order Boltzmann Machines.

The high-order Boltzmann machine (HOBM) approximates probability distributions defined on a set of binary variables, through a learning algorithm that uses Monte Carlo methods. The approximation distribution is a normalized exponential of a consensus function formed by high-degree terms and the structure of the HOBM is given by the set of weighted connections. We prove the convexity of the Kullback-Leibler divergence between the distribution to learn and the approximation distribution of the HOBM. We prove the convergence of the learning algorithm to the strict global minimum of the divergence, which corresponds to the maximum likelihood estimate of the connection weights, establishing the uniqueness of the solution. These theoretical results do not hold in the conventional Boltzmann machine, where the consensus function has first and second-degree terms and hidden units are used. Copyright 1996 Elsevier Science Ltd.

Journal Article↗
PubMedDate not supplied

Evaluation of a pharmaceutical care education series for chain pharmacists using the focus group method.

OBJECTIVES: (1) Describe a pharmaceutical care education program presented to a group of pharmacists employed by a large pharmacy chain; (2) present the results of a formative evaluation of that program, and show how these can be used to improve subsequent offerings of the program as well as to enhance the efforts of other pharmacies and colleges involved in similar ventures; and (3) describe the focus group method in detail and demonstrate its usefulness as an evaluation tool. DESIGN AND PARTICIPANTS: Two pharmacist focus groups and two patient focus groups. SETTING: Chain pharmacy corporation and two colleges of pharmacy. MAIN OUTCOME MEASURES: Effects on attitudes and practice. RESULTS: The focus group method is useful for this type of evaluation. The educational series had a positive effect on pharmacists' attitudes and reported practice behavior. However, these improvements were not obvious to patients. Small group learning modules that include cases or problem-based exercises are probably effective vehicles for achieving educational goals. CONCLUSION: The chain pharmacy corporation should revise the educational program and expose more pharmacist-employees to it. This company and others should consider providing off-site, in-person education to employee pharmacists that makes use of an interactive, small group format. Although effective, the focus group method could have been improved by a more rigorous patient recruitment process and greater structure to the debriefing sessions for staff.

Adult↗
PubMed2006

Global landscape of protein complexes in the yeast Saccharomyces cerevisiae.

Identification of protein-protein interactions often provides insight into protein function, and many cellular processes are performed by stable protein complexes. We used tandem affinity purification to process 4,562 different tagged proteins of the yeast Saccharomyces cerevisiae. Each preparation was analysed by both matrix-assisted laser desorption/ionization-time of flight mass spectrometry and liquid chromatography tandem mass spectrometry to increase coverage and accuracy. Machine learning was used to integrate the mass spectrometry scores and assign probabilities to the protein-protein interactions. Among 4,087 different proteins identified with high confidence by mass spectrometry from 2,357 successful purifications, our core data set (median precision of 0.69) comprises 7,123 protein-protein interactions involving 2,708 proteins. A Markov clustering algorithm organized these interactions into 547 protein complexes averaging 4.9 subunits per complex, about half of them absent from the MIPS database, as well as 429 additional interactions between pairs of complexes. The data (all of which are available online) will help future studies on individual proteins as well as functional genomics and systems biology.

Biological Evolution↗
PubMed2004

Support vector machines for separation of mixed plant-pathogen EST collections based on codon usage.

MOTIVATION: Discovery of host and pathogen genes expressed at the plant-pathogen interface often requires the construction of mixed libraries that contain sequences from both genomes. Sequence identification requires high-throughput and reliable classification of genome origin. When using single-pass cDNA sequences difficulties arise from the short sequence length, the lack of sufficient taxonomically relevant sequence data in public databases and ambiguous sequence homology between plant and pathogen genes. RESULTS: A novel method is described, which is independent of the availability of homologous genes and relies on subtle differences in codon usage between plant and fungal genes. We used support vector machines (SVMs) to identify the probable origin of sequences. SVMs were compared to several other machine learning techniques and to a probabilistic algorithm (PF-IND) for expressed sequence tag (EST) classification also based on codon bias differences. Our software (Eclat) has achieved a classification accuracy of 93.1% on a test set of 3217 EST sequences from Hordeum vulgare and Blumeria graminis, which is a significant improvement compared to PF-IND (prediction accuracy of 81.2% on the same test set). EST sequences with at least 50 nt of coding sequence can be classified using Eclat with high confidence. Eclat allows training of classifiers for any host-pathogen combination for which there are sufficient classified training sequences. AVAILABILITY: Eclat is freely available on the Internet (http://mips.gsf.de/proj/est) or on request as a standalone version. CONTACT: friedel@informatik.uni-muenchen.de.

Algorithms↗
PubMed1989

EMG cranial muscle levels in headache sufferers before and during headache.

It has long been assumed that the origin of pain in 'muscle-contraction headache' lies in the peri-cranial muscles, especially in the frontales. Pain, it is assumed, is experienced when the muscles are in spasm. It is further assumed that learned reductions in muscle tone between headache episodes will reduce the probability of future pain episodes. In this experiment, details are given of EMG measures made on the frontal, occipital, and neck muscles of separate groups of migraine and tension headache subjects. The measures were made before the onset of head pain and later when the same subjects reported pain. As part of the experiment, subjects were exposed to an experimental stressor during the pain-free period, and these results were compared with those of a group of non-headache subjects. Results showed that the headache groups did not differ on any of the pre-headache measures. Neck muscle levels varied markedly when compared with control subjects who had comparatively low levels reactive to an experimental stressor. When the data taken during the headache phase were analysed according to diagnosis, the occipital muscle output was found to be significantly lower in the migraine group and higher in the tension group.

Adult↗