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Obstacles to effective developmental surveillance: errors in clinical reasoning.

Recent research and legislation support the importance of early identification and intervention for children with developmental and behavioral or emotional problems. Detecting these children often depends on medical professionals, especially pediatricians. However, few pediatricians use developmental screening tests to help them identify children. Rather, physicians usually rely on their clinical impressions to discriminate children with and without difficulties. Research on the accuracy of clinical impressions, although sparse, suggests that only half the children in need are identified. The most obvious reasons, such as severity of the problem or the type of clinical information physicians select (e.g., parents' concerns, observations of the child, history, etc.), do not fully explain why some children are identified and others are not. More complete explanations are found in research on clinical impression formation that suggests physician's selection from the array of clinical data is mediated by their unique experiences, beliefs, and attitudes. These qualities provide a set of judgment heuristics for sorting seemingly relevant from irrelevant information. Judgment heuristics, depending on their content, may lead to accurate or inaccurate impressions. This article suggests a model of ideal impression formation that may help physicians learn to more accurately identify children with developmental and behavioral or emotional problems.

Child↗

Recognizing names in biomedical texts: a machine learning approach.

MOTIVATION: With an overwhelming amount of textual information in molecular biology and biomedicine, there is a need for effective and efficient literature mining and knowledge discovery that can help biologists to gather and make use of the knowledge encoded in text documents. In order to make organized and structured information available, automatically recognizing biomedical entity names becomes critical and is important for information retrieval, information extraction and automated knowledge acquisition. RESULTS: In this paper, we present a named entity recognition system in the biomedical domain, called PowerBioNE. In order to deal with the special phenomena of naming conventions in the biomedical domain, we propose various evidential features: (1) word formation pattern; (2) morphological pattern, such as prefix and suffix; (3) part-of-speech; (4) head noun trigger; (5) special verb trigger and (6) name alias feature. All the features are integrated effectively and efficiently through a hidden Markov model (HMM) and a HMM-based named entity recognizer. In addition, a k-Nearest Neighbor (k-NN) algorithm is proposed to resolve the data sparseness problem in our system. Finally, we present a pattern-based post-processing to automatically extract rules from the training data to deal with the cascaded entity name phenomenon. From our best knowledge, PowerBioNE is the first system which deals with the cascaded entity name phenomenon. Evaluation shows that our system achieves the F-measure of 66.6 and 62.2 on the 23 classes of GENIA V3.0 and V1.1, respectively. In particular, our system achieves the F-measure of 75.8 on the "protein" class of GENIA V3.0. For comparison, our system outperforms the best published result by 7.8 on GENIA V1.1, without help of any dictionaries. It also shows that our HMM and the k-NN algorithm outperform other models, such as back-off HMM, linear interpolated HMM, support vector machines, C4.5, C4.5 rules and RIPPER, by effectively capturing the local context dependency and resolving the data sparseness problem. Moreover, evaluation on GENIA V3.0 shows that the post-processing for the cascaded entity name phenomenon improves the F-measure by 3.9. Finally, error analysis shows that about half of the errors are caused by the strict annotation scheme and the annotation inconsistency in the GENIA corpus. This suggests that our system achieves an acceptable F-measure of 83.6 on the 23 classes of GENIA V3.0 and in particular 86.2 on the "protein" class, without help of any dictionaries. We think that a F-measure of 90 on the 23 classes of GENIA V3.0 and in particular 92 on the "protein" class, can be achieved through refining of the annotation scheme in the GENIA corpus, such as flexible annotation scheme and annotation consistency, and inclusion of a reasonable biomedical dictionary. AVAILABILITY: A demo system is available at http://textmining.i2r.a-star.edu.sg/NLS/demo.htm. Technology license is available upon the bilateral agreement.

Abstracting and Indexing↗

Trauma in the arctic: an incident report.

On January 29, 1989, a military aircraft crashed on approach to an airfield in Alaska. The subsequent extraction, evacuation, and casualty resuscitation occurred at temperatures lower than -50 degrees F. Both the medical and military literature are replete with instructions and advice regarding the handling of trauma victims in the field in the Arctic environment; however, case reviews of such incidents are rare. In this case, the circumstances of the incident, and the organizations on which it fell, argued for almost ideal handling of the care of the victims. Problems that have an impact on the availability of casualty management, generally, in the Arctic such as a widely scattered population and sparse medical facilities, poorly defined evacuation routes, and marginal communication patterns, were not encountered in this review because of the unusual circumstances of this incident. The difficulties of field care in this environment, even under "ideal" conditions, however, are real and evident in this case history. Transportation assets are critical. Rehearsal, critique, refinement, and re-rehearsal of a mass casualty plan can significantly increase victim survival. Proper protocols and confidence in them take on an importance far beyond their benefit in a more temperate environment. Procedures must be worked out in advance, known by all concerned, and practiced, because the "rescuer" is at the same risk of hypothermia as the "victim" and, in addition, is responsible for thinking for the incapacitated patient. Rote-learned drills will be acknowledged far longer in the cold than unspecific guidelines. Survival for trauma victims may depend on those rote actions.

Accidents, Aviation↗

Grand rounds: what is the point?

INTRODUCTION The chalkboards are no longer only chalkboards but are PowerPoint presentations. Textbooks are rarely texts but rather CDs to be downloaded at a reader's discretion; and classrooms are almost optional. Still the university hospital environment reflects a belief in the pedagogic effectiveness of the 19th century medical wisdom by encouraging and maintaining grand rounds. What makes the grand rounds is debatable. The large crowds, which historically attended to hear and to feast on a specialist's pearls of wisdom, have been replaced by sparse crowds often inattentive and in a rush to be elsewhere. This survey was designed to assess the status of the grand round in Canada. We contacted the 16 medical schools via e-mail and asked either the chairperson or the obs-gyn grand round coordinator to respond to a 2-page questionnaire. The Association of professors of Obstetrics and Gynecology (APOG) assisted in diffusing and collecting the data.

Canada↗

A comparison of the role of dynorphin in the hippocampal mossy fiber pathway in guinea pig and rat.

Several behavioral studies in rat (Gallagher, 1988) have suggested that opioids in the hippocampus could play an important role in learning and memory. However, in this species, very few reports specifically address the issue of physiological actions of opioids released by the mossy fibers which constitute the principal source of dynorphin and enkephalin in the hippocampus. In the guinea pig high frequency stimulation of mossy fibers causes a transient heterosynaptic inhibition of neighboring mossy fibers (Weisskopf et al., 1993) or perforant path synapses in the dentate (Wagner et al., 1993), which is mediated by the synaptic release of dynorphin that activates presynaptic kappa receptors. We show here that neither exogenous nor endogenous dynorphin affect mossy fiber excitatory postsynaptic potentials in the Sprague-Dawley rat, which is consistent with the finding that kappa receptor binding in the mossy fiber termination zone is dense in the guinea pig and sparse in this rat. More surprisingly, although kappa receptor binding is found in the rat dentate gyrus molecular layer and in the CA3 pyramidal cell layer, dynorphin had no action on perforant path field responses, somatic potassium currents or evoked monosynaptic inhibitory postsynaptic currents in CA3 cells. This lack of action appears to be an exception among rodents as dynorphin significantly inhibited mossy fiber responses in the hamster, mouse, and even another strain of rat, Long-Evans. Unlike the kappa mediated actions, the mu opioid receptor agonist DAMGO inhibited Sprague-Dawley mossy fiber responses, as it does in guinea pig. In contrast to other investigators, however, we found that the opioid receptor antagonist naloxone had no effect on Sprague-Dawley mossy fiber LTP.

Animals↗

Artificial neural networks as a novel approach to integrated pharmacokinetic-pharmacodynamic analysis.

A novel model-independent approach to analyze pharmacokinetic (PK)-pharmacodynamic (PD) data using artificial neural networks (ANNs) is presented. ANNs are versatile computational tools that possess the attributes of adaptive learning and self-organization. The emulative ability of neural networks is evaluated with simulated PK-PD data, and the power of ANNs to extrapolate the acquired knowledge is investigated. ANNs of one architecture are shown to be flexible enough to accurately predict PD profiles for a wide variety of PK-PD relationships (e.g., effect compartment linked to the central or peripheral compartment and indirect response models). Also, an example is given of the ability of ANNs to accurately predict PD profiles without requiring any information regarding the active metabolite. Because structural details are not required, ANNs exhibit a clear advantage over conventional model-dependent methods. ANNs are proved to be robust toward error in the data and perturbations in the initial estimates. Moreover, ANNs were shown to handle sparse data well. Neural networks are emerging as promising tools in the field of drug discovery and development.

Mathematical Computing↗

Cognitive functioning and well-being in euthyroid patients on thyroxine replacement therapy for primary hypothyroidism.

OBJECTIVE: Hypothyroidism is associated with neurocognitive impairment. Sparse data suggest that treatment of hypothyroidism, resulting in a return to euthyroidism, may be associated with only partial recovery of overall neurocognitive functioning. The aim of this study was to assess neurocognitive functioning and well-being in euthyroid patients with primary hypothyroidism on adequate thyroxine (T4) treatment. We also investigated whether serum TSH and thyroid antibodies are determinants of neurocognitive functioning and well-being. DESIGN: We assessed neurocognitive functioning and well-being in 141 patients with primary hypothyroidism. METHODS: Neurocognitive test results and scores on questionnaires measuring well-being of 141 patients were compared with the reference values for these tests as published and used in Dutch clinical neuropsychological practice. Assessment of neurocognitive functioning included tests for cognitive or psychomotor speed, attention, working memory as well as learning and memory. Well-being was measured with the Symptom Check List-90 total score and the Rand 36-item Health Survey subscales for 'mental health' and 'vitality'. RESULTS: Patients showed poor performance on various domains of neurocognitive functioning compared with mean standard reference values, especially on a complex attention task and on verbal memory tests. Levels of well-being were significantly lower for patients compared with those of the general population. Neither serum TSH nor thyroid antibodies were determinants of neurocognitive functioning and well-being. CONCLUSION: The results of this study suggest that neurocognitive functioning as well as psychological well-being may not be completely restored in patients with hypothyroidism, despite T4 treatment.

Adult↗

Heritability and prevalence of specific fears and phobias in childhood.

Fears and phobias are relatively common in childhood. Both environmental and genetic theories have tried to explain the etiology behind these conditions. However, data supporting the different theories are sparse. To investigate the relative importance of genetic and environmental influences on specific phobias and fears, parental reports of animal, situational, and mutilation fears and phobias were completed for 1106 pairs of 8- to 9-year-old Swedish twins. The prevalence of specific phobias was 7.3% for boys and 10.0% for girls. Genetic. shared environmental, and nonshared environmental effects contributed to individual differences in fears and phobias in young children, but the magnitude of the effects differed between sexes. Shared environmental effects contributed to a general susceptibility for fearfulness. Genetic and nonshared environmental effects, on the other hand, contributed both to the general susceptibility and specific fearfulness, even though these effects primarily were fear specific. These results indicate that both heritable factors as well as environmental factors such as trauma, vicarious learning, and/or negative information are important for differences in fearfulness and phobias--at least in children.

Age Distribution↗

Preserved knowledge of maps of countries: implications for the organization of semantic memory.

We describe two patients with selectively preserved knowledge of the category of countries. Following a series of cerebral infarcts, patient DB presented with severe perceptual impairment, including dense apperceptive agnosia,prosopagnosia, and topographical agnosia. Despite these deficits, he could effortlessly name countries from their outline maps. Patient WH, who suffered from semantic dementia, had severe naming and comprehension difficulties, with extremely sparse residual semantic knowledge. Remarkably, the category of countries was preserved. First, we argue that, for both patients, this category preservation occurs at a semantic level. Second, we discuss our findings in the context of three current models of category-specific effects (perceptual, ontogenetic, and evolutionary models). We argue that the perceptual model (Humphreys and colleagues) cannot easily accommodate our findings. By contrast, the ontogenetic (Warrington and colleagues) and evolutionary models (Caramazza and colleagues) can explain our findings. However, some modifications to both models are required. The ontogenetic model needs to envisage a spatial channel for the development of map knowledge, which is anatomically separate from channels of other categories of knowledge. The evolutionary model needs to envisage the possibility that some categories of knowledge, such as countries, may not be prewired, but learned during ontogenetic development.

Aged↗

Density-dependent accumulation of basic fibroblast growth factor in the subendothelial matrix.

Recent evidence indicates that basic fibroblast growth factor (bFGF), which lacks a conventional signal recognition sequence, is a component of the subendothelial matrix. However, the molecular mechanisms regulating its cellular release and subsequent matrix deposition remain equivocal. To examine the cellular and subcellular mechanisms regulating bFGF release and subendothelial sequestration, we generated polyclonal antibodies against a chemically cross-linked bFGF. We then used anti-bFGF IgG in conjunction with 3T3 cell [3H]thymidine incorporation assays, enzyme immunoassays and immunofluorescence to learn whether bFGF accumulation in the subendothelial matrix is dependent upon endothelial cell (EC)-cell contact, which coincides with growth arrest. In contrast to subconfluent cultures, which lacked any detectable extracellular matrix bFGF localization, bovine aortic and microvascular EC plated at confluent densities displayed a punctate extracellular staining pattern that was abolished when EC were pretreated with 10 micrograms/ml cycloheximide. Additionally, when EC were treated with either 1 mM beta-D xyloside, an inhibitor of proteoglycan assembly, or 100 micrograms/ml heparin, there was a 40% reduction in matrix-associated bFGF (quantified by image analysis of antibody stained cultures). 3T3 [3H]thymidine incorporation assays indicated that the beta-D xyloside-induced reduction of matrix-associated bFGF coincided with a significant increase in bFGF activity in the conditioned media. Neither sparsely-plated nor confluent EC cultures possessed specific bFGF localization of the nuclear compartment when cells were fixed using cold methanol; however, when EC were fixed in formaldehyde and lysed in isotonic buffers containing 0.1% Triton X-100 or absolute acetone, there was a marked decrease in anti-bFGF staining of the postconfluent extracellular matrix and a concomitant increase in nuclear fluorescence. Because bFGF-stimulated vascular cell growth has been implicated in controlling neointimal cell proliferation, we screened normal and atherosclerotic coronary blood vessels for bFGF, but we were unable to detect it either in lesioned or normal intima. In contrast, significant bFGF levels were observed in association with the EC and mesangial cells of the renal corpuscle, where heparan sulfate accumulates within the glomerular basement membrane. Our in vitro results suggest that bFGF accumulates within the proteoglycan-containing subendothelial matrix concomitant with the formation of cell-cell contacts. In situ, the composition of the microvascular matrix and the cellular phenotype may facilitate the selective accumulation of bFGF that we observed. This, in turn, may influence vascular morphogenesis and remodeling during angiogenesis.

3T3 Cells↗

"Where have all the students gone?" Retaining medical school graduates through educational innovations.

CONTEXT: New Mexico is a sparsely populated rural state in the USA, with 20% of New Mexicans living in poverty. There is a need for physicians in the state, especially in primary care. New Mexico's only medical school, the University of New Mexico School of Medicine is state supported. New Mexico and its medical school have a vested interest in its graduates returning to the state to practice. OBJECTIVES: Evaluate the effects of early community preceptorships on graduating physicians' specialty choice and subsequent return to practice in the state where they attended medical school. STRATEGIES: A Primary Care Curriculum (PCC) was introduced into the medical school in 1979. Students expressing interest in this programme were considered. Twenty students per year were assigned to the PCC. The remainder went through the traditional curriculum. The PCC used a problem-based learning model. All PCC students participated in a 16-week, one-on-one community preceptorship (Phase 1B) in a small or rural community during their first year. Graduates from 1983-1996 were analysed for specialty and practice location. MAIN OUTCOMES: Of the 294 students doing Phase 1B, 99 (40%) returned to New Mexico to practice compared to 221 (32%) of traditional students. Fifty-eight (23%) of the Phase 1B students practice primary care compared to 112 (16%) of the traditional students. CONCLUSION: Self-selected students choosing and participating in early community-based clinical experiences coupled with problem-based learning are more likely to return to the state and to practice primary care.

Career Choice↗

Synaptic plasticity at the cerebellum input stage: mechanisms and functional implications.

The mf-GrC relay provides the case of a synapse at which elementary neurotransmission mechanisms are particularly well understood allowing a precise investigation of synaptic plasticity. An interesting consequence is that a presynaptic mechanism of LTP could be precisely documented on the basis of quantal analysis. By being presynaptically expressed, LTP becomes instrumental to regulation of short-term synaptic dynamics thereby controlling time-dependent transformations of the incoming mossy fiber input. It is unknown to what extent these considerations could be generalized, but early observations were provided for comparable concepts and mechanisms in neocortical synapses (Tsodyks and Markram, 1997). Although several aspects remain to be investigated, mf-GrC LTP provides a wide substrate for information storage in the cerebellum. In the rat cerebellum, there are 10(11) GrCs and 4 times as many mf-GrC synapses. Mathematical models have suggested that mf-GrC LTP improves mutual information transfer, and that the combination of synaptic and non-synaptic changes improves sparse representation of the mf input (Schweighofer et al., 2000; Philipona et al., 2003). Moreover, mf-GrC LTP could play a key role in regulating neurotransmission dynamics, implementing adaptability in delay lines early envisioned by Breitenberg (1967) and then revisited by Medina and Mauk (2002). These observations challenge the simple view of spatial pattern separation proposed by Marr (1969). The potential consequences of mf-GrC LTP need to be further investigated and confronted with computational models of the cerebellar network.

Afferent Pathways↗

Techniques for rapid quantitative assessment of activity levels in small-group tutorials.

Two techniques for the rapid quantitative analysis of student participation in small-group teaching were investigated. In the first approach an observer, who also acted as a 'critical friend', recorded the length of individual contributions using a computer keyboard as a simple timing device. In the second approach, small-group sessions were recorded with a portable stereophonic audiotape recorder. The teacher was recorded on one channel, all students on the other. A computer program produced automated analysis of these small group interactions by computing relative amount of speech on each channel. Simple analysis produced automatically by the programs revealed the overall style of the tutorial--variably 'mini-lectures' by teachers with very little participation by the student body, rapid 'question and answer' sessions with about equal teacher/student body involvement or 'mini-presentations' by students with the teacher offering sparse comments in the manner of a facilitator. By presenting results in a graphic format, teachers can be given rapid objective feedback on their teaching style. Coupled with short verbal/non-verbal quizzes at the end of tutorials and information from other assessments, the value of using levels of participation as a measure of the efficiency of such small-group sessions can itself be assessed.

Computer-Assisted Instruction↗

Comorbidity in ADHD: implications for research, practice, and DSM-V.

OBJECTIVE: Since the introduction of DSM-III/III-R, clinicians and investigators have shown increasing interest in the study of conditions comorbid with attention-deficit hyperactivity disorder (ADHD). Better understanding ADHD comorbidity patterns is needed to guide treatment, research and future classification approaches. METHOD: The ADHD literature from the past 15 years was reviewed to (1) explore the most prevalent patterns of ADHD comorbidity; (2) examine the correlates and longitudinal predictors of comorbidity; and (3) determine the extent to which comorbid patterns convey unique information concerning ADHD etiology, treatment and outcomes. To identify potential new syndromes, the authors examined comorbid patterns based on eight validational criteria. RESULTS: The largest available body of literature concerned the comorbidity with ADHD and conduct disorder/aggression, with a substantially smaller amount of data concerning other comorbid conditions. In many areas the literature was sparse, and pertinent questions concerning comorbidity patterns remain unexplored. Nonetheless available data warrant the delineation of two new subclassifications of ADHD: (1) ADHD aggressive subtype, and (2) ADHD, anxious subtype. CONCLUSIONS: Additional studies of the frequency of comorbidity and associated factors are greatly needed to include studies of differential effects of treatment of children with various comorbid ADHD disorders, as well as of ADHD children who differ on etiological factors.

Aggression↗

Sexual health education for people with mental health problems: what can we learn from the literature?

Research into sexual risk behaviour among people with 'severe' mental health problems suggested that they are likely to engage in high-risk sexual behaviour, for a number of reasons, putting them at risk of sexually transmitted diseases. The aim of this review is to describe approaches, content and outcomes of sexual health education programmes, developed and implemented for people with mental health problems. A literature review from 1980 to 2005 was carried out using the electronic databases CINAHL, PsycINFO, British Nursing Index, Pubmed and Medline, and the Cochrane library was also searched. The literature search was confined to papers written in English. The keywords 'sexuality', 'sexual health education', 'sexual health promotion', 'HIV', 'sexually transmitted disease' were combined with 'mental illness', 'chronic mental illness''severe mental illness''persistent mental illness''psychiatry', 'mental disorder', 'education interventions' and 'evaluation'. A vast amount of literature was recovered on sexual risk behaviour in people with severe mental health problems, and sexual dysfunction as a result of prescribed medication. As the focus of the review was on sexual health education, this literature was omitted. Although the literature on sexual health education for people experiencing mental health problems was sparse, 14 studies were located that either described or evaluated sexual health education programmes. Most sex education programmes focused on topics such as HIV and other sexually transmitted diseases, negotiating safe sex and skill development in condom use. Findings suggested that the people who attended benefited from sexual health education programmes, facilitated in a sensitive and supportive manner. Education tended to produce a reduction in sexual risk behaviour as opposed to complete cessation. Nevertheless, it is appropriate to consider integrating such education with service provision. The results of the review provide guidance to service providers and mental health nurses wishing to develop and evaluate sexual health education programmes for service users. Areas for future research are also identified.

Attitude to Health↗

Ocular shape and myopia.

INTRODUCTION: To learn if eye shape might be a useful parameter in refractive research. MATERIALS AND METHODS: Laboratory research on eye growth mechanisms is summarised. The available clinical literature relating refraction to eye shape and peripheral refraction is critically assessed in the context of the laboratory research on refractive development. RESULTS: Almost all refraction research assesses optical and length parameters exclusively along the visual axis. Contemporary laboratory research demonstrates a remarkable phylogenic conservation of the neural mechanisms regulating refractive development. On-axis image quality regulates central refractive development in animals and probably, to some extent, in humans. Off-axis image quality at the retina depends on anterior segment geometry and optics, and on the 3-dimensional conformation of the retina. In chicks, eye shape is a predictable parameter linked to the underlying neural mechanisms modulating eye development. Based on the sparse clinical literature in human adults and children, the eye shapes induced in chicks are also seen in human subjects in patterns suggesting that eye shape may be a useful parameter in clinical studies. CONCLUSION: The diverse findings suggest that incorporating the 3-dimensional conformation of the eye into future clinical studies may help resolve many of the ambiguities in contemporary refractive research.

Animals↗

Localization of met-enkephalin and vasoactive intestinal polypeptide in the brains of male zebra finches.

An interconnected series of brain nuclei controls song learning and behavior in male zebra finches (Poephila guttata). This study examined the distribution of fibers, terminals, and somata immunoreactive for two neuropeptides, methionine-enkephalin (ENK) and vasoactive intestinal polypeptide (VIP), in song-control nuclei of adult males. In addition, the broad pattern of major regions of labeling throughout the forebrain and midbrain was determined. The telencephalic song-control nuclei MAN (magnocellular nucleus of the anterior neostriatum), Area X of the striatum, HVC (higher vocal center), and RA (robust nucleus of the archistriatum) contained abundant ENK immunoreactivity, including labeled fibers and somata. In addition, intensely labeled fibers and terminals were seen in the thalamic nucleus DLM (medial portion of the dorsolateral nucleus of the anterior thalamus). High levels of VIP immunoreactivity were also seen in MAN, HVC, and RA, but this label consisted of fiber and terminals only. Area X and surrounding striatum contained extremely sparsely distributed VIP-labeled processes. Somata positive for VIP were not seen throughout cortical regions such as the neostriatum and hyperstriatum but were abundant in the lateral striatum (paleostriatum augmentatum, PA) and may contribute to a dense field of terminal labeling seen in the globus pallidus. The apparent presence of a robust VIP-positive striato-pallidal projection is not typical of major basal ganglia pathways in vertebrates, raising the possibility that passerine birds have diverged from the typical amniote pattern.

Animals↗

Mean field and capacity in realistic networks of spiking neurons storing sparsely coded random memories.

Mean-field (MF) theory is extended to realistic networks of spiking neurons storing in synaptic couplings of randomly chosen stimuli of a given low coding level. The underlying synaptic matrix is the result of a generic, slow, long-term synaptic plasticity of two-state synapses, upon repeated presentation of the fixed set of the stimuli to be stored. The neural populations subtending the MF description are classified by the number of stimuli to which their neurons are responsive (multiplicity). This involves 2p + 1 populations for a network storing p memories. The computational complexity of the MF description is then significantly reduced by observing that at low coding levels (f), only a few populations remain relevant: the population of mean multiplicity - pf and those of multiplicity of order square root pf around the mean. The theory is used to produce (predict) bifurcation diagrams (the onset of selective delay activity and the rates in its various stationary states) and to compute the storage capacity of the network (the maximal number of single items used in training for each of which the network can sustain a persistent, selective activity state). This is done in various regions of the space of constitutive parameters for the neurons and for the learning process. The capacity is computed in MF versus potentiation amplitude, ratio of potentiation to depression probability and coding level f. The MF results compare well with recordings of delay activity rate distributions in simulations of the underlying microscopic network of 10,000 neurons.

Algorithms↗