Biomedical subjects

G J Ortega

Publications and source records attributed to G J Ortega.

4 recordsLinked to original sources

PubMed2006

Role of transport performance for neuron cell morphology.

The compartmental model is a basic tool for studying signal propagation in neurons; if the model parameters are adequately redefined, it can also be helpful in the study of electrical or fluid transport in other biological systems. Here we show that the input resistance in different networks that simulate the morphology of neurons is the result of the interplay between the relevant conductances, neuron morphology, and neuron size. The results suggest that neurons may grow in such a way that facilitates the current flow to the synapses, concurrently minimizing power consumption.

Animals↗

PubMed2001

Detecting determinism in high-dimensional chaotic systems.

A method based upon the statistical evaluation of the differentiability of the measure along the trajectory is used to identify determinism in high-dimensional systems. The results show that the method is suitable for discriminating stochastic from deterministic systems even if the dimension of the latter is as high as 13. The method is shown to succeed in identifying determinism in electroencephalogram signals simulated by means of a high-dimensional system.

Journal Article↗

PubMed1994

Statistical and dynamical analysis of circadian rhythms.

Time series of core temperature in golden hamsters with or without access to a running wheel were analyzed using statistical tools and Dynamical Systems theory. Although the statistical analysis did not show any striking difference between the two groups (other than clearer spectra in the case in the animals with access to wheels), a clear dynamical difference was found. The circadian temperature of hamsters with access to wheel running exhibited fewer degrees of freedom than those without access to them (1.728 vs 11.548). Thus, it may be argued that wheel running synchronizes the ciradian organization of hamsters.

Animals↗

PubMedDate not supplied

[The pathophysiological foundations of temporal-lobe epilepsy: studies in humans and animals].

INTRODUCTION: Temporal lobe epilepsy (TLE) is the most frequent form of pharmaco-resistant epilepsy in human. Research using material from TLE patients undergoing surgery and animal models has significantly increased in the last decade. DEVELOPMENT: We review recent findings obtained over the last years from electrophysiological and anatomical studies in human and animal models of TLE. Data suggest a large heterogeneity and inter-individual variability depending on the model and the system under study. However, a common principle that appears to underlie the epileptic condition is the reorganization of excitation and inhibition resulting in hyperexcitability. Recent research combining in vitro electrophysiology together with depth recordings in vivo and new analytical methodologies is also discussed. CONCLUSIONS: A multidisciplinary approach using both human and animal models can help to fill gaps in our knowledge and to provide unique insights into the pathophysiology of TLE.

Animals↗