Computer modeling of a spinal reflex circuit

Dalcin, Bruno Luiz Galluzzi; Cruz, Frederico Alan de Oliveira; Cortez, Célia Martins; Passos, Emmanuel

doi:10.1590/s0103-97332005000600013

Cited by 12 publications

(10 citation statements)

References 24 publications

(30 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we adopted the same synaptic conditions used by Dalcin et al (2005). We have considered that the postsynaptic effect created by a single impulse reaching the presynaptic terminal was a subthreshold stimulus for the postsynaptic membrane.…”

Section: Description Of the Modelmentioning

confidence: 99%

“…where P R is the resting potential, P o is the synaptic reversal potential, τ P is the time constant of the period after the hyperpolarization potential, T R is the threshold potential at rest, T o is the excitation threshold after AP, τ H is the decay time constant for the relative refractory period and t p is the absolute refractory period (Dalcin et al 2005).…”

Section: Description Of the Modelmentioning

confidence: 99%

“…3, 4 and 5 allow including some synapses characteristics (facilitation, adaptive process, after-firing mechanism, post-tetanic facilitation, and fatigue) in the problem (Dalcin et al 2005).…”

Section: Description Of the Modelmentioning

confidence: 99%

See 2 more Smart Citations

Computational modeling of synchronization process of the circadian timing system of mammals

et al. 2009

Self Cite

View full text Add to dashboard Cite

This paper presents a model for the circadian temporization system of mammals which associates the synchronization dynamics of coupling oscillators to a set of equations able to reproduce the synaptic characteristics of somatodendritic membrane of neurons. The circadian timing system is organized in a way to receive information from the external and internal environments, and its function is the timing organization of physiological and behavioral processes in a circadian pattern. Circadian timing system in mammals is constituted by a group of structures which includes the suprachiasmatic nucleus, the intergeniculate leaflet and the pineal gland. In suprachiasmatic nucleus are found neuron groups working as a biological pacemaker-the so-called biological master clock. By means of numerical simulations using the Kuramoto model, we simulated the dynamics behavior of the biological pacemaker. For this we used a set of 1,000 coupled oscillators with long-range coupling, which were distributed on a 10 x 10 x 10 spherical lattice, and a new method to estimate the order parameter, which characterizes the degree of synchronization of oscillator system. Our model has been able to produce frequency responses in accordance with physiological patterns, and to reproduce two fundamental characteristics of biological rhythms: the endogenous generation and synchronization to the light-dark cycle.

show abstract

Section: Description Of the Modelmentioning

confidence: 99%

Section: Description Of the Modelmentioning

confidence: 99%

See 1 more Smart Citation

Computational modeling of synchronization process of the circadian timing system of mammals

et al. 2009

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our model, these potentials are given by Equation 7: where P R is the resting potential, P o is the synaptic reversal potential, τ P is the time constant of the period after potential hyperpolarization, T R is the threshold potential at rest, T o is the excitation threshold after AP, τ H is the decay time constant for the relative refractory period, and t p is the absolute refractory period. Here, we adopted the same synaptic conditions as used by Dalcin et al (17).…”

Section: Model Adoptedmentioning

confidence: 99%

A simple model for circadian timing by mammals

Cardoso

Cruz

Silva

et al. 2009

Braz J Med Biol Res

View full text Add to dashboard Cite

Circadian timing is structured in such a way as to receive information from the external and internal environments, and its function is the timing organization of the physiological and behavioral processes in a circadian pattern. In mammals, the circadian timing system consists of a group of structures, which includes the suprachiasmatic nucleus (SCN), the intergeniculate leaflet and the pineal gland. Neuron groups working as a biological pacemaker are found in the SCN, forming a biological master clock. We present here a simple model for the circadian timing system of mammals, which is able to reproduce two fundamental characteristics of biological rhythms: the endogenous generation of pulses and synchronization with the light-dark cycle. In this model, the biological pacemaker of the SCN was modeled as a set of 1000 homogeneously distributed coupled oscillators with long-range coupling forming a spherical lattice. The characteristics of the oscillator set were defined taking into account the Kuramoto's oscillator dynamics, but we used a new method for estimating the equilibrium order parameter. Simultaneous activities of the excitatory and inhibitory synapses on the elements of the circadian timing circuit at each instant were modeled by specific equations for synaptic events. All simulation programs were written in Fortran 77, compiled and run on PC DOS computers. Our model exhibited responses in agreement with physiological patterns. The values of output frequency of the oscillator system (maximal value of 3.9 Hz) were of the order of magnitude of the firing frequencies recorded in suprachiasmatic neurons of rodents in vivo and in vitro (from 1.8 to 5.4 Hz).

show abstract

“…According to Abbot and Regeher (2004), the synaptic plasticity and the range of operation timescales suggest that long-term changes in the transmission properties of synapses provide a physiological substrate for learning and memory, whereas short-term changes support a variety of computations. Indeed, synapses have a very active role in information processing, and several computational models of learning and memory, as well as motor-sensory processing, have been proposed in the last years, based on present knowledge about synaptic characteristic and neuronal processing (Cruz et al, 2007;Becker, 2005;Cruz and Cortez, 2005;Dalcin et al, 2005). Neuroimaging experiments have revealed that emotionally charged stimuli have a greater modulatory effect on sensorial cortex and some subcortical structures than on the neutral ones (Mourão-Miranda, 2003, Lane 1999.…”

Section: Stress Effects On the Cerebral Functionsmentioning

confidence: 99%

Psycological and physiological responses to stress: a review based on results from PET and MRI studies

Cortez

Cruz

Silva

2008

Braz. arch. biol. technol.

Self Cite

View full text Add to dashboard Cite

A new application for the nuclear imaging techniques is the study of organic responses to stress. Neuroimaging techniques allow the assessment of brain activation changes in association with the metabolic responses to stress. In this paper, a review of general effects of the stress on organic activity is made, emphasizing important advances introduced by studies using PET and fMRI. The importance of the hypothalamus-pituitary-adrenal axis to onset the adequate psychical and organic responses to sustain the homeostasis during the stress is discussed, as well as the possibility of traumatic stressing experiences have negative effects on the brain.

show abstract

Computer modeling of a spinal reflex circuit

Cited by 12 publications

References 24 publications

Computational modeling of synchronization process of the circadian timing system of mammals

Computational modeling of synchronization process of the circadian timing system of mammals

A simple model for circadian timing by mammals

Psycological and physiological responses to stress: a review based on results from PET and MRI studies

Contact Info

Product

Resources

About