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1.
Ellingson P. J. Korogod S. M. Kahl T. M. Kulagina I. B. Makedonsky I. A. Cymbalyuk G. S. 《Neurophysiology》2019,51(5):312-321
Neurophysiology - Gastrointestinal motility is based on the rhythmic activity of interstitial cells of Cajal (ICCs). The ICC rhythm generation relies upon characteristic Ca2+-handling mechanisms... 相似文献
2.
Jessica R. Parker Alexander N. Klishko Boris I. Prilutsky Gennady S. Cymbalyuk 《PLoS computational biology》2021,17(12)
Mutually inhibitory populations of neurons, half-center oscillators (HCOs), are commonly involved in the dynamics of the central pattern generators (CPGs) driving various rhythmic movements. Previously, we developed a multifunctional, multistable symmetric HCO model which produced slow locomotor-like and fast paw-shake-like activity patterns. Here, we describe asymmetric features of paw-shake responses in a symmetric HCO model and test these predictions experimentally. We considered bursting properties of the two model half-centers during transient paw-shake-like responses to short perturbations during locomotor-like activity. We found that when a current pulse was applied during the spiking phase of one half-center, let’s call it #1, the consecutive burst durations (BDs) of that half-center increased throughout the paw-shake response, while BDs of the other half-center, let’s call it #2, only changed slightly. In contrast, the consecutive interburst intervals (IBIs) of half-center #1 changed little, while IBIs of half-center #2 increased. We demonstrated that this asymmetry between the half-centers depends on the phase of the locomotor-like rhythm at which the perturbation was applied. We suggest that the fast transient response reflects functional asymmetries of slow processes that underly the locomotor-like pattern; e.g., asymmetric levels of inactivation across the two half-centers for a slowly inactivating inward current. We compared model results with those of in-vivo paw-shake responses evoked in locomoting cats and found similar asymmetries. Electromyographic (EMG) BDs of anterior hindlimb muscles with flexor-related activity increased in consecutive paw-shake cycles, while BD of posterior muscles with extensor-related activity did not change, and vice versa for IBIs of anterior flexors and posterior extensors. We conclude that EMG activity patterns during paw-shaking are consistent with the proposed mechanism producing transient paw-shake-like bursting patterns found in our multistable HCO model. We suggest that the described asymmetry of paw-shaking responses could implicate a multifunctional CPG controlling both locomotion and paw-shaking. 相似文献
3.
The phenomenon of transformation of E. coli cells under electric treatment has been studied. The cells of strains MH 1, HB 101 and DH 1 after EDTA treatment in an isotonic medium were transformed with DNA pBR322 by applying a single exponential pulse (E = 10 kV/cm, T = 1.5 ms) to the suspension. The maximum transformation efficiency obtained was 4 X 10(6) colonies/micrograms DNA. The maximum transformation frequency was 0.4% at a DNA concentration of 15 micrograms/ml. 相似文献
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A system that controls the leg movement of an animal or a robot walking over irregular ground has to ensure stable support
for the body and at the same time propel it forward. To do so, it has to react adaptively to unpredictable features of the
environment. As part of our study of the underlying mechanisms, we present here a model for the control of the leg movement
of a 6-legged walking system. The model is based on biological data obtained from the stick insect. It represents a combined
treatment of realistic kinematics and biologically motivated, adaptive gait generation. The model extends a previous algorithmic
model by substituting simple networks of artificial neurons for the algorithms previously used to control leg state and interleg
coordination. Each system controlling an individual leg consists of three subnets. A hierarchically superior net contains
two sensory and two ‘premotor’ units; it rhythmically suppresses the output of one or the other of the two subordinate nets.
These are continuously active. They might be called the ‘swing module’ and the ‘stance module’ because they are responsible
for controlling the swing (return stroke) and the stance (power stroke) movements, respectively. The swing module consists
of three motor units and seven sensory units. It can produce appropriate return stroke movements for a broad range of initial
and final positions, can cope with mechanical disturbances of the leg movement, and is able to react to an obstacle which
hinders the normal performance of the swing movement. The complete model is able to walk at different speeds over irregular
surfaces. The control system rapidly reestablishes a stable gait when the movement of the legs is disturbed.
Received: 13 July 1994/Accepted in revised form: 15 November 1994 相似文献
6.
Korogod S. M. Maksymchuk N. V. Demianenko L. E. Vlasov O. O. Cymbalyuk G. S. 《Neurophysiology》2020,52(5):324-333
Neurophysiology - Transient receptor potential melastatin 8 channels (TRPM8s) are molecular sensors of temperature. They are expressed in primary afferent neurons (PANs) and function as receptors... 相似文献
7.
Background
Multistability of oscillatory and silent regimes is a ubiquitous phenomenon exhibited by excitable systems such as neurons and cardiac cells. Multistability can play functional roles in short-term memory and maintaining posture. It seems to pose an evolutionary advantage for neurons which are part of multifunctional Central Pattern Generators to possess multistability. The mechanisms supporting multistability of bursting regimes are not well understood or classified.Methodology/Principal Findings
Our study is focused on determining the bio-physical mechanisms underlying different types of co-existence of the oscillatory and silent regimes observed in a neuronal model. We develop a low-dimensional model typifying the dynamics of a single leech heart interneuron. We carry out a bifurcation analysis of the model and show that it possesses six different types of multistability of dynamical regimes. These types are the co-existence of 1) bursting and silence, 2) tonic spiking and silence, 3) tonic spiking and subthreshold oscillations, 4) bursting and subthreshold oscillations, 5) bursting, subthreshold oscillations and silence, and 6) bursting and tonic spiking. These first five types of multistability occur due to the presence of a separating regime that is either a saddle periodic orbit or a saddle equilibrium. We found that the parameter range wherein multistability is observed is limited by the parameter values at which the separating regimes emerge and terminate.Conclusions
We developed a neuronal model which exhibits a rich variety of different types of multistability. We described a novel mechanism supporting the bistability of bursting and silence. This neuronal model provides a unique opportunity to study the dynamics of networks with neurons possessing different types of multistability. 相似文献8.
The dynamic behavior of a model of two electrically coupled oscillatory neurons was studied while the external polarizing current was varied. It was found that the system with weak coupling can demonstrate one of five stable oscillatory modes: (1) in-phase oscillations with zero phase shift; (2) antiphase oscillations with halfperiod phase shift; (3) oscillations with any fixed phase shift depending on the value of the external polarizing current; (4) both in-phase and antiphase oscillations for the same current value, where the oscillation type depends on the initial conditions; (5) both in-phase and quasiperiodic oscillations for the same current value. All of these modes were robust, and they persisted despite small variations of the oscillator parameters. We assume that similar regimes, for example antiphase oscillations, can be detected in neurophysiological experiments. Possible applications to central pattern generator models are discussed. 相似文献
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Apoptosis modulatory activities of transiently expressed Bcl-2: Roles in cytochrome c release and Bax regulation 总被引:12,自引:0,他引:12
Hou Q Cymbalyuk E Hsu SC Xu M Hsu YT 《Apoptosis : an international journal on programmed cell death》2003,8(6):617-629
Bcl-2 and Bcl-XL are pro-survival members of the Bcl-2 family. These proteins have been shown to antagonize the pro-apoptotic activity of Bax and promote cell survival through blocking Bax translocation from the cytosol to mitochondria and by preventing the release of cytochrome c. However, it has been recently reported that transiently expressed Bcl-2 unexpectedly leads to significant cell toxicity. To study this intriguing phenomenon, we have carried out further analyses into the properties of transiently expressed Bcl-2. We found that various isoforms of human and different species of Bcl-2 were equally capable of inducing apoptosis. In addition, we discovered that transient expression of Bcl-2, unlike its pro-survival homolog Bcl-XL, can lead to the release of cytochrome c from mitochondria and that the resulting cell death can be inhibited by caspase and calpain inhibitors. Moreover, we have shown that unlike the pro-apoptotic protein Bid, the toxicity associated with the transient expression of Bcl-2 occurs independent of the activity of the endogenous Bax. Finally, we found that in spite of its intrinsic toxicity, transiently expressed Bcl-2 is fully capable of blocking the ectopically expressed Bax from localizing to mitochondria. Taken together, these studies demonstrate that transiently expressed Bcl-2 displays opposing functional properties. 相似文献