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PubMed2006

Evaluation of a shape-based model of human face discrimination using FMRI and behavioral techniques.

Understanding the neural mechanisms underlying object recognition is one of the fundamental challenges of visual neuroscience. While neurophysiology experiments have provided evidence for a "simple-to-complex" processing model based on a hierarchy of increasingly complex image features, behavioral and fMRI studies of face processing have been interpreted as incompatible with this account. We present a neurophysiologically plausible, feature-based model that quantitatively accounts for face discrimination characteristics, including face inversion and "configural" effects. The model predicts that face discrimination is based on a sparse representation of units selective for face shapes, without the need to postulate additional, "face-specific" mechanisms. We derive and test predictions that quantitatively link model FFA face neuron tuning, neural adaptation measured in an fMRI rapid adaptation paradigm, and face discrimination performance. The experimental data are in excellent agreement with the model prediction that discrimination performance should asymptote as faces become dissimilar enough to activate different neuronal populations.

Adolescent↗
PubMed2002

Rapid adaptation to internal states as a coding strategy in visual cortex?

Adaptation is a prominent feature of biological neuronal systems. A common interpretation of adaptation in terms of function is that it provides flexibility for a neuronal system to perform well under varying external conditions, for example by adjusting the input/output relation of a sensory system with reference to the ensemble of stimuli the organism currently perceives. This interpretation, however, only applies if the time-scale of adaptation is slower than the time-scale at which the environment changes. Experimentally it is observed, however, that adaptation can be very rapid. Spike-frequency adaptation of cortical neurons, for example, occurs on a time-scale of approximately 100 ms. Here we show that those rapid adaptation processes can also be understood within the framework of information theory. We start with the hypothesis that neuronal codes are designed to optimize the information a neuronal representation conveys about an input stimulus for any increasing time window beginning with stimulus onset, and we show that this implies a rapid adaptation of the neuronal code on the time-scale of stimulus presentation. Adaptation, however, does not occur because the state of the environment changes. Rather it is a reaction to changes of the organisms own internal state, e.g. the level of noise in the neuronal representation. We apply this approach to a model of an orientation hypercolumn in the primary visual cortex, and predict that inter-columnar interactions should adapt on the time-scale of a typical fixation period ( approximately 300 ms).

Adaptation, Psychological↗
PubMed2001

The prediction of stress fractures using a 'stressed volume' concept.

This paper addresses an anomaly which exists in the current literature regarding stress fractures. Analysis of the data on fatigue strength of bone samples in vitro would conclude that these fractures should never occur at the strain levels known to occur in vivo. This anomaly can be resolved by including in the analysis the effect of stressed volume, whereby larger volumes of material are expected to have worse fatigue properties. A Weibull analysis was used to predict the probability of failure, Pf; this was an upper-bound prediction because it did not include the effects of remodelling and adaptation. Combining this analysis with a finite element model of the human tibia, we predicted a Pf value of 21% after five weeks of strenuous exercise, which is comparable with reported incidences in military personnel. The high incidence of stress fractures in the cannon bone of racehorses could also be predicted (Pf = 62%, compared to 70% experimentally). The approach can be used to investigate the effect of variables in the exercise regime such as the distance run per day and the use of improved footwear. It can also predict the increased risk of stress fractures in elderly people. The results suggest certain simple rules which may be of clinical value in designing exercise regimes and in understanding the risk factors for this type of injury.

Animals↗
PubMed1995

Four aspects of strategic change: contributions to children's learning of multiplication.

This study reports a longitudinal investigation of French 2nd graders' acquisition of single-digit multiplication skill. Speed, accuracy, and strategy use were assessed 3 times within the year when children learned multiplication. The data showed that improvements in speed and accuracy that generally accompany learning can reflect at least 4 types of specific strategic changes: introduction of new strategies, increasing use of the most efficient existing strategies, more efficient execution of each strategy, and more adaptive choices among strategies. The data also showed substantial continuities in learning: At all 3 points of measurement, children used multiple strategies, used retrieval most often on the same classes of problems, and used repeated addition on the most difficult problems. Stable individual differences were also apparent. The findings supported a number of predictions of Siegler and Shipley's (1995) adaptive strategy choice model. Implications for understanding learning, arithmetic, and strategy choice processes are discussed.

Child↗
PubMed2002

Effects of biomechanical stress on bones in animals.

The signals that allow bone to adapt to its mechanical environment most likely involve strain-mediated fluid flow through the canalicular channels. Fluid can only be moved through bone by cyclic loading, and the shear stresses generated on bone cells are proportional to the rate of loading. The proportional relation between fluid shear stresses on cells and loading rate predicts that the magnitude of bone's adaptive response to loading should be proportional to strain rate. For lower loading frequencies within the physiologic range, experimental evidence shows this is true. It is also true that the mechanical sensitivity of bone cells saturates quickly, and that a period of recovery either between loading cycles or between periods of exercise can optimize adaptive response. Together, these concepts suggest that short periods of exercise, with a 4-8 h rest period between them, are a more effective osteogenic stimulus than a single sustained session of exercise. The data also suggest that activities involving higher loading rates are more effective for increasing bone formation, even if the duration of the activity is short.

Adaptation, Physiological↗
PubMed2026

BriGHT: transcriptome-regularized multimodal neuroimaging for brain disorder prediction.

MOTIVATION: Hypergraph-based models for brain disorder prediction mainly adopt imaging-derived hypergraphs as propagation backbones. However, the entanglement of topology construction and feature propagation leaves regional representations weakly constrained by underlying biological organization, making them vulnerable to subject-specific variation and noise, particularly in heterogeneous multimodal settings. RESULTS: We present BriGHT, a Brain transcriptome-reGularized Hypergraph framework for mulTimodal disorder prediction. BriGHT employs a transcriptome-derived structural reference as a soft anchoring prior to regularize neuroimaging ROI embeddings, stabilizing representation geometry while preserving disease-relevant subject-specific variation. BriGHT further incorporates a reliability-aware fusion module to estimate subject-specific modality reliability from prediction confidence, cross-modal consistency, and decision certainty, enabling adaptive integration under heterogeneous modality quality. Experiments on three neuroimaging cohorts (ADNI, ADHD-200, REST-meta-MDD) and four modalities (VBM, fMRI, FDG, AV45) demonstrate that BriGHT consistently outperforms competing graph/hypergraph learning methods across six brain disorder prediction tasks. Perturbation analyses show that BriGHT benefits from the spatial correspondence between transcriptomic modules and imaging ROIs, rather than from arbitrary hypergraph regularization alone. Ablation and meta-analytic interpretability analyses support the contribution of transcriptomic anchoring and adaptive fusion to robust and biologically meaningful brain disorder prediction. AVAILABILITY: The software is publicly available at: https://github.com/Yaolab-fantastic/BriGHT. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Journal Article↗
PubMed1979

Salt taste adaptation: the psychophysical effects of adapting solutions and residual stimuli from prior tastings on the taste of sodium chloride.

The paper reviews how adaptation to sodium chloride, changing in concentration as a result of various experimental procedures, affects measurements of the sensitivity, intensity, and quality of the salt taste. The development of and evidence for the current model that the salt taste depends on an adaptation level (taste zero) determined by the sodium cation concentration is examined and found to be generally supported, despite great methodological complications. It would seem that lower adaptation levels elicit lower thresholds, higher intensity estimates, and altered quality descriptions with predictable effects on psychophysical measures.

Adaptation, Physiological↗
PubMedDate not supplied

[Value of brain ultrasound studies of newborn infants for prediction of neurological development in the 1st year of life].

BACKGROUND: Recent advances in perinatology have been associated with a decrease in perinatal mortality. However, nowadays detailed assessments are of major importance for accurate prediction of neurologic development of extreme low birth weight infants and term infants with severely disturbed postnatal adaptation. This study examined the role of cranial ultrasound for the prediction of developmental progress during the first year of life. PATIENTS AND METHODS: Fifty nine infants with gestational age less than 33. weeks and fifty seven infants with gestational age above 32. weeks were studied. Each infant was classified as normal, suspect or abnormal using cranial ultrasound and a specialized scoring system during the first days and twelve month of life. Repeated structured neurological examination were carried out during the first year of corrected age. By statistical analysis was investigated the correlation between the degree of ultrasound abnormalities and neurological outcome of neonates of both different gestational age groups. RESULTS: We diagnosed the same share of pathological ultrasound scans in both groups within the first days of life. In contrast there were remarkable differences concerning the results of sonographic investigation at the end of the first year of life. We demonstrated a significant higher incidence of abnormal findings in neonates with a gestational age less than 33 weeks at this point of time. The neurological progress of neonates of both groups was significantly disturbed in cases of major sonographic abnormalities. Cases of mild or moderate ultrasound abnormalities were significantly associated with a poor neurologic outcome only in neonates with a gestational age less than 33 weeks. By statistical analysis we proved a significant value of cranial ultrasound for prediction of neurological development of preterm neonates with gestational age less than 33 weeks. The certainty prediction of neurodevelopmental sequelae in neonates with gestational age above 32 weeks was associated with major sonographic abnormalities but not with mild or moderate sonographic pathology. CONCLUSION: The prognostic accuracy of ultrasound scans performed in the first week of life is important for preterm neonates with gestational age less than 33 weeks. In neonates with gestational age above 32 weeks we revealed no significant predictive value of the method. This limits the value of this technique in this patients as a reliable method for recognising of the infants with the need of early rehabilitation.

Brain Damage, Chronic↗
PubMedDate not supplied

A computational study of feedback effects on signal dynamics in a mitogen-activated protein kinase (MAPK) pathway model.

Exploiting signaling pathways for the purpose of controlling cell function entails identifying and manipulating the information content of intracellular signals. As in the case of the ubiquitously expressed, eukaryotic mitogen-activated protein kinase (MAPK) signaling pathway, this information content partly resides in the signals' dynamical properties. Here, we utilize a mathematical model to examine mechanisms that govern MAPK pathway dynamics, particularly the role of putative negative feedback mechanisms in generating complete signal adaptation, a term referring to the reset of a signal to prestimulation levels. In addition to yielding adaptation of its direct target, feedback mechanisms implemented in our model also indirectly assist in the adaptation of signaling components downstream of the target under certain conditions. In fact, model predictions identify conditions yielding ultra-desensitization of signals in which complete adaptation of target and downstream signals culminates even while stimulus recognition (i.e., receptor-ligand binding) continues to increase. Moreover, the rate at which signal decays can follow first-order kinetics with respect to signal intensity, so that signal adaptation is achieved in the same amount of time regardless of signal intensity or ligand dose. All of these features are consistent with experimental findings recently obtained for the Chinese hamster ovary (CHO) cell lines (Asthagiri et al., J. Biol. Chem. 1999, 274, 27119-27127). Our model further predicts that although downstream effects are independent of whether an enzyme or adaptor protein is targeted by negative feedback, adaptor-targeted feedback can "back-propagate" effects upstream of the target, specifically resulting in increased steady-state upstream signal. Consequently, where these upstream components serve as nodes within a signaling network, feedback can transfer signaling through these nodes into alternate pathways, thereby promoting the sort of signaling cross-talk that is becoming more widely appreciated.

Animals↗
PubMed2001

Predicting the emergence of resistance to antifungal drugs.

The emergence of antifungal drug resistance is inevitable. Here I discuss antibiotic resistance in the context of the adaptive potential of fungi and I propose an approach to predicting the evolution of antifungal resistance using experimental evolution of DNA sequences and microbial populations. Prediction is based on determination of evolutionary potential at two levels, the gene and the genome. At the level of the gene, evolutionary potential depends on the sequence space of candidate resistance genes defined by the fitness effects of all possible mutations in all possible combinations. At the level of the genome, evolutionary potential depends on the adaptive landscape defined by the fitness effects of all possible interactions among alleles constituting the genotype.

Antifungal Agents↗
PubMed1995

Complete sequence of the RNA genome of human rhinovirus 16, a clinically useful common cold virus belonging to the ICAM-1 receptor group.

We report here the complete nucleotide sequence and predicted polyprotein sequence of HeLa cell-adapted human rhinovirus 16 (HRV16). This virus is more suitable than human rhinovirus 14 (HRV14) for clinical studies, and its growth and physical properties are favorable for biochemical and crystallographic analysis. The complete message-sense RNA genome of HRV16 is composed of 7124 bases, not including the poly(A) tail. An open reading frame, extending from base 626 to 7084 predicts a polyprotein containing 2152 amino acid residues. Comparison with other rhinovirus sequences shows HRV16 is much more representative of human rhinoviruses than HRV14. No apparent relationship was found between receptor group and amino acid sequence in VP1, the capsid protein bearing the binding site for the intercellular adhesion molecule-1 (ICAM-1) in both HRV14 and HRV16.

Base Sequence↗
PubMed1994

Nucleotide and deduced amino acid sequences of the matrix (M) and fusion (F) protein genes of cetacean morbilliviruses isolated from a porpoise and a dolphin.

Morbilliviruses have been isolated from stranded dolphins and porpoises. The present paper describes the cloning and sequencing of the porpoise morbillivirus (PMV) F gene and of the dolphin morbillivirus (DMV) M and F genes and their flanking regions. The gene order of the DMV genome appeared to be identical to that of other morbilliviruses. A genomic untranslated region of 837 nucleotides was found between the translated DMV M and F gene regions. The predicted DMV M protein were highly conserved with those of other morbilliviruses. Both the deduced PMV and DMV F0 proteins exhibited three major hydrophobic regions as well as a cysteine rich region, a leucine zipper motif and a cleavage motif allowing cleavage of the F0 protein into F1 and F2 subunits. Apparently the DMV F0 cleavage motif was not modified by adaptation of DMV to Vero cells. The predicted PMV and DMV F proteins were 94% identical. Comparisons with the corresponding sequences of other morbilliviruses demonstrated that the cetacean morbillivirus does not derive from any known morbillivirus but represents an independent morbillivirus lineage.

Amino Acid Sequence↗
PubMed2005

A biomechanical model for size, speed and anatomical variations of the energetic costs of running mammals.

Here we propose a model of energetic costs and the muscle-tendon unit function on running mammals. The main goal is to set a simple theoretical framework which gives an understanding of the biomechanical principles behind the size, speed and anatomical variations of the energetic costs of running mammals. The model is a point-like mass withstood by a two-segment leg with an extensor muscle serially attached to a tendon. We considered withstanding body weight during the stance phase as the main role of the muscle-tendon unit during fast locomotion. The ground reaction force dependence on speed and the time of stance phase as well as other biomechanical characteristics were taken from previous empirical studies of running. At the same time, the morphological variations with body mass were taken from empirically well-established allometric equations for mammals. The metabolic cost was estimated from an empirical equation relating metabolic power with muscular force and speed in shortening and stretching. Our model predicts the pattern of mass specific metabolic rate variations with both speed and body mass. It also gives an explanation of the experimentally reported linear inverse relationship between the rate of energy used for running and the time of application of force by the foot to the ground during each stride. It also suggests an explanation of the unusual energy saving adaptations of large macropodids. It provides some predictions on the relationship, between energy costs and muscle-tendon unit characteristics, testable on further experiments.

Animals↗
PubMed1976

REM sleep and adaptation of psychiatric patients: an application of sleep studies.

The authors used sleep laboratory data to predict responses to psychiatric treatment. The predictions were based on the assumptions that REM latency reflects the need for dreaming and therefore the need for adaptation and that REM time reflects the capacity for the adaptive work associated with REM sleep. Dream recall and dream content were considered indicators of psychological mindedness and the patient's current conflicts. With this material, statistically significant predictions of such outcomes as good response to psychotherapy, elopement, or need for medication were made. The results of this study support the hypothesis that REM sleep is involved in adaptation.

Adaptation, Psychological↗
PubMed2006

Predicting medication-free treatment response in acute psychosis: cross-validation from the Finnish Need-Adapted Project.

This study tested predictors of 2-year antipsychotic-free response from the Soteria study (older, better social functioning, fewer cardinal symptoms) using data from the Finnish Acute Psychosis Integrated treatment study. The quasi-experimental study compared need-adapted family-oriented psychosocial intervention within a 3-week antipsychotic-free trial to psychosocial intervention plus antipsychotic medications. Forty-six percent of experimental completers (37% of intent-to-treat subjects) were successfully treated without antipsychotic medications for the entire 2-year study. The DSM-III-R diagnoses of schizophrenia and schizophreniform disorder and Soteria-suggested predictors were not related to antipsychotic-free response. Different variables within the same domains of good prognosis and fewer schizophrenia symptoms predicted antipsychotic-free response or nonresponse with 74% accuracy. The 6-month duration of symptom criterion distinguishing schizophrenia from schizophreniform disorder does not separate medication-free treatment responders from those requiring medications. Prognosis appears related to antipsychotic-free response and may be helpful in distinguishing schizophrenia from schizophreniform disorder in early episodes.

Acute Disease↗
PubMed1989

Predictive value of hormonal profiles before stimulation for in vitro fertilization.

Ovarian responses to stimulation for in vitro fertilization by clomiphene citrate menotropins have been correlated to the hormonal profiles determined during spontaneous cycles. The authors found 80% of high plasmatic luteinizing hormone (LH) and/or androgens levels associated with an inappropriated response: premature LH surge, multifollicular ovarian response, or dissociated cystic response, versus only 11% with appropriated responses. High plasmatic follicle-stimulating hormone existed in 71% of the no response group. Detryptoréline, a luteinizing hormone-releasing hormone agonist associated with menotropins, in a "short procedure" maintained the adequate responses and suppressed premature LH surges. The no response group was moderately improved, as were multifollicular and dissociated cystic response groups. Hormonal profiles could be useful predictive factors of the ovarian response for adaptation on the first procedure of stimulation.

Adult↗
PubMed2002

Cognitive requirements for hawk-dove games: A functional analysis for evolutionary design.

Like other social animals, humans play adaptively important games, and current evolutionary theory predicts special-purpose, domain-specific cognitive mechanisms for playing such games. We offer a functional analysis of the information requirements for successfully playing one important social game, the "hawk-dove" conflict-of-interest game, developing new graphic conventions for doing so. In particular, we address the orders of recognition necessary for successfully playing such games, showing that there are adaptive advantages of capacities for first, second, third, and fourth such orders, but no more. We suggest that first-order recognition is not only the most basic in analytic terms but is likely to have been the first to evolve, with subsequent orders added later in evolution.

Journal Article↗
PubMed1985

Method for assessment of experimental allergy in guinea pigs adapted to cosmetic ingredients.

2 protocols are presented to predict and assess allergic reactions after application of chemicals or cosmetic products, either raw materials or finished products. The first is an open epidermal induction and challenge, the intensity of the reaction being maximized by injecting Freund's complete adjuvant into the foot pad. The second allows detection of weaker allergens and is a quasi-intradermal induction: both the adjuvant and test substance are injected into the foot pad. In both protocols, the challenge consisted of a single topical application in the lumbar region of 10 microliter of test substance and components, allowing study of cross-sensitization, the large surface available permitting 6 different contacts.

Administration, Topical↗