Dynamics of histograms of differences between the successive electrocardiogram <Emphasis Type="Italic">RR</Emphasis> intervals over 24 hours as an index of the balanced state of neurogenic influences on the heart rate

The quantitative parameters of the balanced influence of the sympathetic and parasympathetic divisions of the autonomic nervous system, including the variation range of the histogram of differences between successive electrocardiogram RR intervals, the number of zero differences, and the sum of differences between successive RR intervals, are suggested.     

Motor program coding representation from a handwriting generator model: The production of line responses

In this paper, a model is employed that describes handwriting behaviors activated by curvilinear and angular velocity generators postulated to initiate and regulate pen tip velocity profiles. This model accounts for the observed differences between straight and curved line production and the effect of movement precues on these responses. Of particular interest is the observed interaction between precue information and line execution type for reaction time. It is shown that differences in reaction time can be explained by the model as a function of the number of parameters that need to be specified. Moreover, there is some evidence that the biomechanical system reacts in a privileged manner to command pulses for specific directions, and that the central nervous system attempts to compensate for these asymmetries. These data are some of the first to show that the benefits of precue extend beyond reaction time and that movement execution characteristics are influenced by motor preparation.     

Nonlinear Dynamical Analysis of the Interdependence Between Central and Autonomic Nervous Systems in Neonates During Sleep

We present in this paper the results of a study of the interdependence between signal characteristic of the central nervous system (electroencephalography) and the autonomic nervous system (heart rate and respiration) in human neonates during sleep. By using methods from nonlinear dynamical systems theory, we show that there exist significant differences in this interdependence with the sleep stage and the electrodes considered. This paves the way for the application of this methodology in clinical practice to study pathologies where this interdependence is altered, such as the sudden infant death syndrome.     

Transplantation of specific human astrocytes promotes functional recovery after spinal cord injury

Repairing trauma to the central nervous system by replacement of glial support cells is an increasingly attractive therapeutic strategy. We have focused on the less-studied replacement of astrocytes, the major support cell in the central nervous system, by generating astrocytes from embryonic human glial precursor cells using two different astrocyte differentiation inducing factors. The resulting astrocytes differed in expression of multiple proteins thought to either promote or inhibit central nervous system homeostasis and regeneration. When transplanted into acute transection injuries of the adult rat spinal cord, astrocytes generated by exposing human glial precursor cells to bone morphogenetic protein promoted significant recovery of volitional foot placement, axonal growth and notably robust increases in neuronal survival in multiple spinal cord laminae. In marked contrast, human glial precursor cells and astrocytes generated from these cells by exposure to ciliary neurotrophic factor both failed to promote significant behavioral recovery or similarly robust neuronal survival and support of axon growth at sites of injury. Our studies thus demonstrate functional differences between human astrocyte populations and suggest that pre-differentiation of precursor cells into a specific astrocyte subtype is required to optimize astrocyte replacement therapies. To our knowledge, this study is the first to show functional differences in ability to promote repair of the injured adult central nervous system between two distinct subtypes of human astrocytes derived from a common fetal glial precursor population. These findings are consistent with our previous studies of transplanting specific subtypes of rodent glial precursor derived astrocytes into sites of spinal cord injury, and indicate a remarkable conservation from rat to human of functional differences between astrocyte subtypes. In addition, our studies provide a specific population of human astrocytes that appears to be particularly suitable for further development towards clinical application in treating the traumatically injured or diseased human central nervous system.     

Development of the peripheral glial cells in Drosophila

In complex organisms the nervous system comprises two cell types: neurons and glial cells. Their correct interplay is of crucial importance during both the development of the nervous system and for later function of the nervous system. In recent years tools have been developed for Drosophila that enable genetic approaches to understanding glial development and differentiation. Focusing on peripheral glial cells we first summarize wild-type development, then introduce some of the relevant genes that have been identified. Despite obvious differences between Drosophila and mammalian glial cells, the molecular machinery that controls terminal differentiation appears well conserved.     

Biogenic amine levels in the cockroach Blaberus craniifer Burm. nervous system.

1. Apart from octopamine, the same indolamines and catecholamines were detected in the whole nervous system of the cockroach Blaberus craniifer Burm., at the same time. 2. However, levels were found to depend on sex, age, and the anatomic region within the nervous system. 3. Although not established, it is thought that these substances act synchronously from the ganglia. 4. The differences in levels between males and females and between anatomical regions during imaginal life suggest, in this species of cockroach, the physiological importance of the metameric organization in metabolic pathways or functional aspects of biogenic amines.     

The role of the plant properties in point-to-point arm movements: a robustness study

In recent papers we demonstrated by means of a modeling study that the smoothness of hand paths and the bell-shaped character of hand velocity profiles which have been experimentally observed in point-to-point arm movements can be largely attributed to the biomechanical properties of the arm rather than to specific planning by the central nervous system. In this paper we present a study of the robustness of our earlier results comprising two goals: (i) the determination of the range of model parameters for which such observations remain valid, (ii) the identification of possible relationships between model parameters and kinematic variables. The results of this study imply three conclusions: (i) the valid range of the tested model parameters (namely the main muscle parameters) is large, (ii) the modeled phenomena are well behaved in that parametric changes do not give rise to bifurcations or other behavioral discontinuities in the analyzed ranges, (iii) there exist precise relationships between certain muscle parameters and the time course of the hand velocity. These results point out that the phenomena observed in our previous work are indeed robust and can lead to useful insights into the mechanisms comprising the regulatory action of the central nervous system as well as into the design principles for biologically inspired artificial arms. Received: 4 December 1995 / Accepted in revised form: 6 November 1996     

Characteristics of autonomic nervous function in Zucker-fatty rats: investigation by power spectral analysis of heart rate variability.

We investigated the characteristics of autonomic nervous function in Zucker-fatty and Zucker-lean rats. For this purpose, a long-term electrocardiogram (ECG) was recorded from conscious and unrestrained rats using a telemetry system, and the autonomic nervous function was investigated by power spectral analysis of heart rate variability (HRV). Although heart rate (HR) in Zucker-fatty rats was lower than that in Zucker-lean rats throughout 24 h, apparent diurnal variation in HR was observed in both strains and HR during the dark period was significantly higher than that in light period. Diurnal variation in locomotor activity (LA) in Zucker-fatty rats was also observed, but LA was lower than that in Zucker lean rats, especially during the dark period. There were no significant differences, however, in high-frequency (HF) power, low-frequency (LF) power, and the LF/HF ratio between Zucker-fatty and Zucker-lean rats. The circadian rhythm of these parameters was mostly preserved in both strains of rats. Moreover, the effect of autonomic blockades on HRV was nearly the same in Zucker-fatty and Zucker-lean rats. These results suggest that the autonomic nervous function of insulin-resistant Zucker-fatty rats remain normal, from the aspect of power spectral analysis of HRV.     

A model for learning human reaching movements

 Reaching movement is a fast movement towards a given target. The main characteristics of such a movement are straight path and a bell-shaped speed profile. In this work a mathematical model for the control of the human arm during ballistic reaching movements is presented. The model of the arm contains a 2 degrees of freedom planar manipulator, and a Hill-type, non-linear mechanical model of six muscles. The arm model is taken from the literature with minor changes. The nervous system is modeled as an adjustable pattern generator that creates the control signals to the muscles. The control signals in this model are rectangular pulses activated at various amplitudes and timings, that are determined according to the given target. These amplitudes and timings are the parameters that should be related to each target and initial conditions in the workspace. The model of the nervous system consists of an artificial neural net that maps any given target to the parameter space of the pattern generator. In order to train this net, the nervous system model includes a sensitivity model that transforms the error from the arm end-point coordinates to the parameter coordinates. The error is assessed only at the termination of the movement from knowledge of the results. The role of the non-linearity in the muscle model and the performance of the learning scheme are analysed, illustrated in simulations and discussed. The results of the present study demonstrate the central nervous system’s (CNS) ability to generate typical reaching movements with a simple feedforward controller that controls only the timing and amplitude of rectangular excitation pulses to the muscles and adjusts these parameters based on knowledge of the results. In this scheme, which is based on the adjustment of only a few parameters instead of the whole trajectory, the dimension of the control problem is reduced significantly. It is shown that the non-linear properties of the muscles are essential to achieve this simple control. This conclusion agrees with the general concept that motor control is the result of an interaction between the nervous system and the musculoskeletal dynamics. Received : 21 May 1996 / Accepted in revised form : 10 June 1997     

Biogenic amine levels in the cockroach Blaberus craniifer burm. nervous system

1. Apart from octopamine, the same indolamines and catecholamines were detected in the whole nervous system of the cockroach Blaberus craniifer Burm., at the same time.2. However, levels were found to depend on sex, age, and the anatomic region within the nervous system.3. Although not established, it is thought that these substances act synchronously from the ganglia.4. The differences in levels between males and females and between anatomical regions during imaginal life suggest, in this species of cockroach, the physiological importance of the metameric organization in metabolic pathways or functional aspects of biogenic amines.     

Cardiorespiratory synchronism: revealing in human,dependence on properties of nervous system and functional states of an organism

Cardiorespiratory synchronism (CRS) shows that at the breathing frequency, which as usual exceeds the baseline heart rhythm, the heart makes one contraction per each breathing. It is shown that CRS arises as a result of reproduction by the heart the rhythm of signals, coming to the heart via vagus nerves. CRS characterized by the synchronization range, duration of its development after the beginning of the rapid respiration, difference between the baseline heartbeat frequency and lower limit of synchronization range. The CRS parameters were determined in humans at the age of 5-65. The CRS parameters depends on nervous system type, vegetative tonus of the nervous system and functional states of an organism.     

Constant brain potentials as neurophysiological markers of autoimmune process]

Neuroimmune interactions in systemic rheumatic diseases were studied. The state of the central nervous system was assessed from the parameters of constant brain potentials, and the state of the immune system, from a complex of immunobiochemical parameters. The highest multiple correlation coefficients were revealed between the immunobiochemical parameters and the parameters of the constant brain potential, which characterize linear and standard deviations of potentials in temporal zones from potentials at other points of recording. The results are discussed in terms of structural and functional integration of the immune and nervous systems.     

Lack of Tryptophan Hydroxylase-1 in Mice Results in Gait Abnormalities

The role of peripheral serotonin in nervous system development is poorly understood. Tryptophan hydroxylase-1 (TPH1) is expressed by non-neuronal cells including enterochromaffin cells of the gut, mast cells and the pineal gland and is the rate-limiting enzyme involved in the biosynthesis of peripheral serotonin. Serotonin released into circulation is taken up by platelets via the serotonin transporter and stored in dense granules. It has been previously reported that mouse embryos removed from Tph1-deficient mothers present abnormal nervous system morphology. The goal of this study was to assess whether Tph1-deficiency results in behavioral abnormalities. We did not find any differences between Tph1-deficient and wild-type mice in general motor behavior as tested by rotarod, grip-strength test, open field and beam walk. However, here we report that Tph1 (−/−) mice display altered gait dynamics and deficits in rearing behavior compared to wild-type (WT) suggesting that tryptophan hydroxylase-1 expression has an impact on the nervous system.     

Genetics of the human electroencephalogram (EEG) and event-related brain potentials (ERPs): a review

Twin and family studies of normal variation in the human electroencephalogram (EEG) and event related potentials (ERPs) are reviewed. Most of these studies are characterized by small sample sizes. However, by summarizing these studies in one paper, we may be able to gain some insight into the genetic influences on individual differences in central nervous system functioning that may mediate genetically determined differences in behavior. It is clear that most EEG parameters are to a large extent genetically determined. The results for ERPs are based on a much smaller number of studies and suggest medium to large heritability.     

High in situ repeatability of behaviour indicates animal personality in the beadlet anemone Actinia equina (Cnidaria)

'Animal personality' means that individuals differ from one another in either single behaviours or suites of related behaviours in a way that is consistent over time. It is usually assumed that such consistent individual differences in behaviour are driven by variation in how individuals respond to information about their environment, rather than by differences in external factors such as variation in microhabitat. Since behavioural variation is ubiquitous in nature we might expect 'animal personality' to be present in diverse taxa, including animals with relatively simple nervous systems. We investigated in situ startle responses in a sea anemone, Actinia equina, to determine whether personalities might be present in this example of an animal with a simple nervous system. We found very high levels of repeatability among individuals that were re-identified in the same locations over a three week sampling period. In a subset of the data, where we used tide-pool temperature measurements to control for a key element of variation in microhabitat, these high levels of repeatability remained. Although a range of other consistent differences in micro-habitat features could have contributed to consistent differences between the behaviour of individuals, these data suggest the presence of animal personality in A. equina. Rather than being restricted to certain groups, personality may be a general feature of animals and may be particularly pronounced in species with simple nervous systems.     

Immunocytological localization of endogenous calcitonin-like molecules in the crustacean Orchestia.

Immunocytological mapping of calcitonin-like molecules (human form) performed in the terrestrial crustacean Orchestia, using PAP procedure on paraffin sections and immunogold method on ultrathin cryosections, reveals two reactive organs: central nervous system and posterior caeca of the midgut. Immunoreactivity within the nervous system is mainly located throughout perikarya and nerve fibers from both dueto- and tritocerebron and ventral nervous chain. Immunolabeling in the posterior caeca is detected on both cell components of the epithelium, with significant quantitative differences between molt and intermolt periods. The role of calcitonin-like substances in these organs is then discussed: at the nervous system level, a neuro transmitter function is suggested; the direct participation of these peptides in the regulation of calcium shifts through the caecal epithelium is hypothesized.     

On the role of the spinal afferent neuron as a generator of extracellular current

The prediction that a system of currents flows between the dorsal column and the dorsal root due to differences in their after-potentials was found to be consistent with the experimental findings. The form, magnitude, duration, and sign of the electrotonic component DRα fulfill the requirements of the postulated system. A contribution of tract after-potentials to the evoked potential of intramedullary structures is indicated. It is a conclusion of this and previous studies that profound changes occur in certain membrane properties of myelinated primary afferent axons as they penetrate the central nervous system. The working concept of abrupt intraaxonal junctional regions is therefore justifiable.     

Immunocytological localization of endogenous calcitonin-like molecules in the crustacean Orchestia

Summary Immunocytological mapping of calcitonin-like molecules (human form) performed in the terrestrial crustacean Orchestia, using PAP procedure on paraffin sections and immunogold method on ultrathin cryosections, reveals two reactive organs: central nervous system and posterior caeca of the midgut. Immunoreactivity within the nervous system is mainly located throughout perikarya and nerve fibers from both deuto- and tritocerebron and ventral nervous chain. Immunolabeling in the posterior caeca is detected on both cell components of the epithelium, with significant quantitative differences between molt and intermolt periods. The role of calcitonin-like substances in these organs is then discussed: at the nervous system level, a neuro transmitter function is suggested; the direct participation of these peptides in the regulation of calcium shifts through the caecal epithelium is hypothesized.