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PubMed2001

The molecular biology of memory storage: a dialogue between genes and synapses.

One of the most remarkable aspects of an animal's behavior is the ability to modify that behavior by learning, an ability that reaches its highest form in human beings. For me, learning and memory have proven to be endlessly fascinating mental processes because they address one of the fundamental features of human activity: our ability to acquire new ideas from experience and to retain these ideas over time in memory. Moreover, unlike other mental processes such as thought, language, and consciousness, learning seemed from the outset to be readily accessible to cellular and molecular analysis. I, therefore, have been curious to know: What changes in the brain when we learn? And, once something is learned, how is that information retained in the brain? I have tried to address these questions through a reductionist approach that would allow me to investigate elementary forms of learning and memory at a cellular molecular level-as specific molecular activities within identified nerve cells.

Animals↗
PubMed2003

A new modulated Hebbian learning rule--biologically plausible method for local computation of a principal subspace.

This paper presents one possible implementation of a transformation that performs linear mapping to a lower-dimensional subspace. Principal component subspace will be the one that will be analyzed. Idea implemented in this paper represents generalization of the recently proposed infinity OH neural method for principal component extraction. The calculations in the newly proposed method are performed locally--a feature which is usually considered as desirable from the biological point of view. Comparing to some other wellknown methods, proposed synaptic efficacy learning rule requires less information about the value of the other efficacies to make single efficacy modification. Synaptic efficacies are modified by implementation of Modulated Hebb-type (MH) learning rule. Slightly modified MH algorithm named Modulated Hebb Oja (MHO) algorithm, will be also introduced. Structural similarity of the proposed network with part of the retinal circuit will be presented, too.

Models, Neurological↗
PubMed2005

Further evidence for the role of inferential reasoning in forward blocking.

Previous studies on human causal learning (De Houwer & Beckers, 2003; De Houwer, Beckers, & Glautier, 2002) showed that secondary task difficulty (performing an easy vs. a difficult secondary task during the main causal learning task) and ceiling information (outcome occurs with a maximal vs. submaximal intensity) had an influence on forward blocking (i.e., lower causal ratings for cue T when AT+ trials are preceded by A+ trials than when no A+ trials are presented). We extended these studies by also examining self-reports of participants about the reasons behind their causal ratings. Blocking was found only for participants who reported an appropriate blocking inference. Furthermore, secondary task difficulty and ceiling information influenced the number of participants who reported an appropriate blocking inference. These findings point to a major impact of inferential reasoning in human causal learning.

Humans↗
PubMed2000

Scopolamine impairs information processing in the hippocampus and performance of a learned eyeblink response in alert cats.

The object of this work was to determine whether the changes in field activity and neuronal excitability recorded in the hippocampus during eyeblink classical conditioning are induced by the cholinergic input, and their relationships with the conditioned response performance. The pyramidal layer field activity, its response to fornix stimulation and eyelid responses were recorded during paired tone-air puff presentations, under scopolamine (25, 50 and 100 microg/kg) or saline administration, following well-established eyeblink conditioning in a trace paradigm in cats. Scopolamine impaired behavioral performance, and, in the hippocampus, disrupted conditioned stimulus-evoked field potential, high frequency shift in field activity, and paired presentation-induced hyperexcitability. These findings indicate that the cholinergic input participates in hippocampal information processing in a way that allows precise conditioned response performance and memory trace formation.

Animals↗
PubMed2004

Internet education of African American consumers on quality of care.

This article describes a study using the Internet to teach African American consumers about quality of health care. By reading information on quality of care, consumers can learn ways to assess the care they are receiving, develop strategies needed to participate effectively in communicating with their health care providers, and make informed decisions in their own best interests. We developed an educational intervention using 5 Internet documents on quality of care and evaluated its effectiveness on learning, value of the information, and satisfaction with the instruction between consumers who read the information alone and those who read the information and interacted with a nurse. Participants indicated they learned a great deal from the information at the Web sites and reported that it would be helpful in assessing their own health care. They more frequently described quality care in terms of health outcomes, self care behaviors, and patient education after the Internet instruction, reflecting important concepts contained in the documents.

Black or African American↗
PubMed1990

The role of information about the response-outcome relation in instrumental discrimination learning.

In 4 instrumental learning experiments, the hierarchical organization among responses (R), outcomes (O), and stimuli (S) was examined. Each experiment explored the possibility that S becomes associated with the R-O relation by providing information about that relation. In each case, an analogy was developed to a paradigm that has been important for concluding that informational relations affect Pavlovian conditioning. Experiments 1 and 2 found an effect of the information that S provides about the R-O relation, using paradigms analogous to blocking and contingency experiments. Experiments 3 and 4 demonstrated a similar result, using a paradigm like that of relative validity. In each case, the experiments pointed to the importance of the information that S gives about the R-O relation, rather than about the individual R and O elements.

Animals↗
PubMed2006

Contextual cueing in naturalistic scenes: Global and local contexts.

In contextual cueing, the position of a target within a group of distractors is learned over repeated exposure to a display with reference to a few nearby items rather than to the global pattern created by the elements. The authors contrasted the role of global and local contexts for contextual cueing in naturalistic scenes. Experiment 1 showed that learned target positions transfer when local information is altered but not when global information is changed. Experiment 2 showed that scene-target covariation is learned more slowly when local, but not global, information is repeated across trials than when global but not local information is repeated. Thus, in naturalistic scenes, observers are biased to associate target locations with global contexts.

Association Learning↗
PubMed2006

Radiologists' preferences for just-in-time learning.

BACKGROUND: Effective learning can occur at the point of care, when opportunities arise to acquire information and apply it to a clinical problem. To assess interest in point-of-care learning, we conducted a survey to explore radiologists' attitudes and preferences regarding the use of just-in-time learning (JITL) in radiology. MATERIALS AND METHODS: Following Institutional Review Board approval, we invited 104 current radiology residents and 86 radiologists in practice to participate in a 12-item Internet-based survey to assess their attitudes toward just-in-time learning. Voluntary participation in the survey was solicited by e-mail; respondents completed the survey on a web-based form. RESULTS: Seventy-nine physicians completed the questionnaire, including 47 radiology residents and 32 radiologists in practice; the overall response rate was 42%. Respondents generally expressed a strong interest for JITL: 96% indicated a willingness to try such a system, and 38% indicated that they definitely would use a JITL system. They expressed a preference for learning interventions of 5-10 min in length. CONCLUSIONS: Current and recent radiology trainees have expressed a strong interest in just-in-time learning. The information from this survey should be useful in pursuing the design of learning interventions and systems for delivering just-in-time learning to radiologists.

Attitude of Health Personnel↗
PubMed1999

What is learned in knowledge-related categories? Evidence from typicality and feature frequency judgments.

When a category's features are tied together by integrative knowledge, subjects learn the category faster than when the features are not directly related. What do subjects learn about the category in such circumstances? Some research has suggested that the subjects can use the knowledge itself in performing the category learning task and, thus, do not learn the details of the category's features. Two experiments investigated this hypothesis by collecting feature frequency estimates after category learning. The results showed that integrative knowledge about a category did not decrease subjects' sensitivity to feature frequency--if anything, knowledge improved it. A third experiment found that integrative knowledge did reduce sensitivity to feature frequency in typicality ratings. The results suggest that knowledge does not inhibit the learning of detailed category information, though it may replace its use in some tasks.

Adult↗
PubMed1998

Spatial and temporal pattern analysis via spiking neurons.

Spiking neurons, receiving temporally encoded inputs, can compute radial basis functions (RBFs) by storing the relevant information in their delays. In this paper we show how these delays can be learned using exclusively locally available information (basically the time difference between the pre- and postsynaptic spikes). Our approach gives rise to a biologically plausible algorithm for finding clusters in a high-dimensional input space with networks of spiking neurons, even if the environment is changing dynamically. Furthermore, we show that our learning mechanism makes it possible that such RBF neurons can perform some kind of feature extraction where they recognize that only certain input coordinates carry relevant information. Finally we demonstrate that this model allows the recognition of temporal sequences even if they are distorted in various ways.

Action Potentials↗
PubMed2001

Language and number: a bilingual training study.

Three experiments investigated the role of a specific language in human representations of number. Russian-English bilingual college students were taught new numerical operations (Experiment 1), new arithmetic equations (Experiments 1 and 2), or new geographical or historical facts involving numerical or non-numerical information (Experiment 3). After learning a set of items in each of their two languages, subjects were tested for knowledge of those items, and new items, in both languages. In all the studies, subjects retrieved information about exact numbers more effectively in the language of training, and they solved trained problems more effectively than untrained problems. In contrast, subjects retrieved information about approximate numbers and non-numerical facts with equal efficiency in their two languages, and their training on approximate number facts generalized to new facts of the same type. These findings suggest that a specific, natural language contributes to the representation of large, exact numbers but not to the approximate number representations that humans share with other mammals. Language appears to play a role in learning about exact numbers in a variety of contexts, a finding with implications for practice in bilingual education. The findings prompt more general speculations about the role of language in the development of specifically human cognitive abilities.

Adult↗
PubMed2005

Frontomedian activation depends on both feedback validity and valence: fMRI evidence for contextual feedback evaluation.

Activation within the posterior frontomedian cortex (pFMC) is suggested to be involved in decision conflict, which typically emerges whenever one does not know which action to choose in order to receive a positive outcome. Decision conflict attenuates due to learning which is often indicated by and therefore confounded with the receipt of increasingly frequent positive and decreasingly frequent negative feedback. The present functional Magnetic Resonance study aimed to disentangle the influence of the factors processing of negative feedback and contextual feedback evaluation on pFMC activation. Participants performed a forced choice paradigm in which they had to decide which one out of two competing stimuli would win in a virtual competition game. In one condition (rule learning, RL), participants were provided with valid feedback so that contextual feedback evaluation had a guiding function for action and thus enabled learning. In contrast, participants received no valid information from feedback in another condition (putative learning, PL) and hence could not learn on the basis of contextual feedback evaluation. However, a learning effect in the latter condition was simulated by gradually increasing the frequency of positive feedback and decreasing the frequency of negative feedback according to a learning model which was derived from pilot data. Importantly, participants were naive with respect to feedback manipulations. Beyond confirming pFMC activation for decision conflicts, a significant interaction between validity and valence of feedback in pFMC revealed the specific contribution of contextual feedback evaluation processes on activation of this area. Not the processing of negative feedback per se, which was found to elicit activation within anterior cingulate cortex, but the evaluation of feedback against the background of the current mental model is suggested to be reflected by pFMC activation.

Adult↗
PubMed2003

Brain-computer interface (BCI) operation: optimizing information transfer rates.

People can learn to control mu (8-12 Hz) or beta (18-25 Hz) rhythm amplitude in the EEG recorded over sensorimotor cortex and use it to move a cursor to a target on a video screen. In the present version of the cursor movement task, vertical cursor movement is a linear function of mu or beta rhythm amplitude. At the same time the cursor moves horizontally from left to right at a fixed rate. A target occupies 50% (2-target task) to 20% (5-target task) of the right edge of the screen. The user's task is to move the cursor vertically so that it hits the target when it reaches the right edge. The goal of the present study was to optimize system performance. To accomplish this, we evaluated the impact on system performance of number of targets (i.e. 2-5) and trial duration (i.e. horizontal movement time from 1 to 4 s). Performance was measured as accuracy (percent of targets selected correctly) and also as bit rate (bits/min) (which incorporates, in addition to accuracy, speed and the number of possible targets). Accuracy declined as target number increased. At the same time, for six of eight users, four targets yielded the maximum bit rate. Accuracy increased as movement time increased. At the same time, the movement time with the highest bit rate varied across users from 2 to 4 s. These results indicate that task parameters such as target number and trial duration can markedly affect system performance. They also indicate that optimal parameter values vary across users. Selection of parameters suited both to the specific user and the requirements of the specific application is likely to be a key factor in maximizing the success of EEG-based communication and control.

Adult↗
PubMed2001

Development of a case-based system for the supervision of an activated sludge process.

The development of a case-based reasoning system for the supervision of an activated sludge process is presented here. The methodology proposed permits the use of past experiences to solve new problems that arise in the process. These experiences are classified as cases or situations. The adaptation of cases and the generation of new cases are used to tune the response of the system and to learn from the new information generated by the process. The case and the case library definition, the initial seed, the search and retrieval process, the adaptation, the action, the evaluation and the learning steps are presented and outlined. The process studied is the wastewater treatment plant of Girona, Spain. Two examples of the response of the system to two different operational situations are presented. The paper also outlines the integration of different fields in a multidisciplinary approach as the most optimal solution to ensure the successful control and supervision of complex processes like the activated sludge process. With this aim the integration of an array of specific supervisory intelligent systems (for the logical analysis and reasoning) and numerical computations for detailed engineering is suggested.

Bacteria↗
PubMed2004

Temporary inactivation of the perirhinal cortex by muscimol injections block acquisition and expression of fear-potentiated startle.

The present study examined the role of the perirhinal cortex (PRh) in aversive information processing and emotional learning. Specifically, we studied the effects of temporary inactivation of the PRh on acquisition and expression of conditioned fear as measured by fear-potentiated startle in rats, as well as on shock sensitization of startle. Temporary inactivation of the PRh was induced by local injections of the GABAA agonist muscimol (0.0, 1.1, 2.2, 4.4 nmol/0.5 micro L). Muscimol injections into the PRh blocked both the expression and acquisition of fear-potentiated startle, as well as shock sensitization of startle. Shock sensitivity was not affected by muscimol injections, indicating that the observed blockade of acquisition and shock sensitization was not caused by a disruption in the perception of shock. Taken together, the present data show that the PRh is critical for the processing of aversive information and is necessary for the expression of emotional learning.

Acoustic Stimulation↗