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Results 701 - 750 of 1344
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Sabatier Nancy - - 2004
In vivo, most vasopressin cells of the hypothalamic supraoptic nucleus fire action potentials in a 'phasic' pattern when the systemic osmotic pressure is elevated, while most oxytocin cells fire continuously. The phasic firing pattern is believed to arise as a consequence of intrinsic activity-dependent changes in membrane potential, and these ...
Oswald Anne-Marie M - - 2004
Burst firing is commonly observed in many sensory systems and is proposed to transmit information reliably. Although a number of biophysical burst mechanisms have been identified, the relationship between burst dynamics and information transfer is uncertain. Electrosensory pyramidal cells have a well defined backpropagation-dependent burst mechanism. We used in vivo, ...
Ikeda Suguru - - 2004
The responses of mechanoreceptor neurons in the antennal chordotonal organ have been examined in cockroaches by intracellular recording methods. The chordotonal organ was mechanically stimulated by sinusoidal movement of the flagellum. Stimulus frequencies were varied between 0.5 and 150 Hz. Receptor neurons responded with spike discharges to mechanical stimulation, and ...
Bhumbra G S - - 2004
Novel approaches to the characterization of coding carried by spike trains are discussed. Measuring firing frequency alone may only partially reflect spike patterning, and can only quantify changes of the most obvious kind. We have devised a method that combines probabilistic and information approaches to quantify the variability of the ...
Dhingra Narender K - - 2004
The quality of the signal a retinal ganglion cell transmits to the brain is important for preception because it sets the minimum detectable stimulus. The ganglion cell converts graded potentials into a spike train with a selective filter but in the process adds noise. To explore how efficiently information is ...
Glantz Raymon M - - 2004
The responses of sustaining and dimming fibers were characterized by the time varying firing rates elicited by extrinsic current and flashes of light. These data were simulated by an adaptive integrate-and-fire model. A postimpulse shunt conductance simulated spike-frequency adaptation. The correlation between observed and model current-elicited impulse rates was 0.94-0.98. ...
Lánský Petr - - 2004
Frequency coding is considered one of the most common coding strategies employed by neural systems. This fact leads, in experiments as well as theoretical studies, to construction of so-called transfer functions, where the output firing frequency is plotted against the input intensity. The term "firing frequency" can be understood differently ...
Daly Kevin C - - 2004
Behavioral studies of olfactory discrimination and stimulus generalization in many species indicate that the molecular features of monomolecular odorants are important for odor discrimination. Here we evaluate how features, such as carbon chain length and functional group, are represented in the first level of synaptic processing. We recorded antennal lobe ...
Kaur Simranjit - - 2004
To examine the basis of frequency receptive fields in auditory cortex (ACx), we have recorded intracellular (whole cell) and extracellular (local field potential, LFP) responses to tones in anesthetized rats. Frequency receptive fields derived from excitatory postsynaptic potentials (EPSPs) and LFPs from the same location resembled each other in terms ...
Massaux A - - 2004
Over the last 10 years, high-frequency bursts of action potentials have been the subject of intense researches to understand their potential role in information encoding. Based on recordings from auditory thalamus neurons (n = 302) collected during anesthesia (pentobarbital, urethan, or ketamine/xylazine), waking (W), and slow-wave sleep (SWS), we investigated ...
Wilson Charles J - - 2004
Subthalamic nucleus neurons exhibit reverse spike-frequency adaptation. This occurs only at firing rates of 20-50 spikes/s and higher. Over this same frequency range, there is an increase in the steady-state frequency-intensity (F-I) curve's slope (the secondary range). Specific blockade of high-voltage activated calcium currents reduced the F-I curve slope and ...
Fiore Lorenzo - - 2003
Multi-unit activity recorded from two electrodes positioned at a distance on a nerve may be analysed by cross-correlation, but units similar in direction and velocity of propagation cannot be distinguished and separately evaluated by this method. To overcome this limit, we added two features, represented by the impulse amplitudes of ...
Ushiba Junichi - - 2003
We reassessed the response properties of peri-stimulus time histograms (PSTHs) in cases when a test stimulus was triggered by a motor-unit discharge with a constant delay time. In this experiment, single motor unit action potentials were recorded from the right tibialis anterior (TA) muscle of five healthy persons. A test ...
Adelman Thomas L - - 2003
The nervous system must observe a complex world and produce appropriate, sometimes complex, behavioral responses. In contrast to this complexity, neural responses are often characterized through very simple descriptions such as receptive fields or tuning curves. Do these characterizations adequately reflect the true dimensionality reduction that takes place in the ...
Passaglia Christopher L - - 2004
To assess the information encoded in retinal spike trains and how it might be decoded by recipient neurons in the brain, we recorded from individual cat X and Y ganglion cells and visually stimulated them with randomly modulated patterns of various contrast and spatial configuration. For each pattern, we estimated ...
Liu Wentai - - 2003
Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are incurable diseases that result in profound vision loss due to degeneration of the light sensing photoreceptors. However, the discovery that direct electrical stimulation of the retinal neurons creates visual sensation has inspired prosthetic devices aimed to restore useful vision in RP/AMD ...
Petit Julien - - 2003
The mechanical properties of motor units have been extensively studied under isometric conditions. Under dynamic conditions, the relationship between the force developed by single motor units and the muscle shortening velocity was determined for relatively high frequencies of activation. However, the interaction between the force-shortening velocity relation and the force-rate ...
Johnson K V B KV School of Kinesiology, Simon Fraser University, BC V5A 1S6, Burnaby, - - 2004
The primary purpose of this study was to examine if there are changes in the intrinsic properties of spinal motoneurons after prolonged submaximal contractions. To do this, we assessed whether or not the synaptic drive to motoneurons needs to increase in order to maintain a constant firing rate of a ...
Neiman Alexander B - - 2004
Our computational analyses and experiments demonstrate that ampullary electroreceptors in paddlefish (Polyodon spathula) contain 2 distinct types of continuously active noisy oscillators. The spontaneous firing of afferents reflects both rhythms, and as a result is stochastically biperiodic (quasiperiodic). The first type of oscillator resides in the sensory epithelia, is recorded ...
Paul Kush - - 2003
A fundamental technical hurdle in systems neurophysiology has been to record the activity of individual neurons in situ while using microstimulation to activate inputs or outputs. Stimulation artifact at the recording electrode has largely limited the usefulness of combined stimulating and recording to using single stimulation pulses or to presenting ...
Valentine Pamela A - - 2003
Intracortical microstimulation (ICMS), consisting of a 40 ms burst (rate 300 Hz) of 10 microA pulses, repetitively administered once per second, for a total duration of 1 h, induced cortical reorganization in the primary auditory cortical field of the anesthetized cat. Multiple single-unit activity was simultaneously recorded from three to ...
Purcell Ian M IM Department of Neurology, UCSD Medical Center, 200 West Arbor Drive, CA 92103-8465, San Diego, - - 2003
In the present study, we report the sensitivity of utricular afferents to sinusoidal translational motion in the horizontal plane. The head orientation was altered relative to the direction of translational travel in 30 degrees increments to allow determination of the head orientation that elicited the maximal and minimal responses of ...
Türker K S - - 2003
Classical techniques for estimating postsynaptic potentials in motoneurones include spike-triggered averages of rectified surface and multiunit electromyographic recordings (SEMG and MU-EMG), as well as the compilation of peristimulus time histograms (PSTH) based on the discharge of single motor units (SMU). These techniques rely on the probability of spike occurrence in ...
Bahar S - - 2003
Phase synchronization between the firing of the crayfish caudal photoreceptor (CPR) and an applied periodic hydrodynamic stimulus is investigated. It is shown that the CPR firing synchronizes with a periodic stimulus over a range of frequencies corresponding to the known sensitivity range of the crayfish to hydrodynamic stimuli. This synchronization ...
Pang Ji-Jie - - 2003
Bipolar cell and amacrine cell synaptic inputs to alpha ganglion cells (alphaGCs) in dark-adapted mouse retinas were studied by recording the light-evoked excitatory cation current (DeltaIC) and inhibitory chloride current (DeltaICl) under voltage-clamp conditions, and the cell morphology was revealed by Lucifer yellow fluorescence with a confocal microscope. Three types ...
Robichaud Daniel R DR - - 2003
Twenty-five rapidly adapting mechanoreceptor afferents were recorded in an in vitro preparation of rat skin and nerve. Single units were recorded while the skin was subjected to dynamic uniaxial stretch using a pseudo-Gaussian noise (PGN) input waveform. Force was the controlled variable in stretch stimuli. Measured loads and displacements were ...
Garabedian Catherine E - - 2003
Rats typically employ 4- to 12-Hz "whisking" movements of their vibrissae during tactile exploration. The intentional sampling of signals in this frequency range suggests that neural processing of tactile information may be differentially engaged in this bandwidth. We examined action potential responses in rat primary somatosensory cortex (SI) to a ...
Rauch Alexander - - 2003
In the intact brain neurons are constantly exposed to intense synaptic activity. This heavy barrage of excitatory and inhibitory inputs was recreated in vitro by injecting a noisy current, generated as an Ornstein-Uhlenbeck process, into the soma of rat neocortical pyramidal cells. The response to such in vivo-like currents was ...
Hunter John D - - 2003
The spike-time reliability of motoneurons in the Aplysia buccal motor ganglion was studied as a function of the frequency content and the relative amplitude of the fluctuations in the neuronal input, calculated as the coefficient of variation (CV). Measurements of spike-time reliability to sinusoidal and aperiodic inputs, as well as ...
Wessberg Johan - - 2003
We recorded, with the microneurography technique, single-unit impulses from nine cutaneous mechanoreceptive afferents with conduction velocities in the C range and receptive fields in the hairy skin of the forearm. The units responded with high impulse rates to light touch and had low monofilament thresholds. The geography of receptive fields ...
Brunel Nicolas - - 2003
When the local field potential of a cortical network displays coherent fast oscillations ( approximately 40-Hz gamma or approximately 200-Hz sharp-wave ripples), the spike trains of constituent neurons are typically irregular and sparse. The dichotomy between rhythmic local field and stochastic spike trains presents a challenge to the theory of ...
Ménard Ariane - - 2003
The effect of multisensory inputs onto the presynaptic inhibitory pathways affecting IA terminals was studied during fictive locomotion in decerebrated cats. The effect was evaluated from changes in amplitude of the monosynaptic excitatory postsynaptic potential (EPSP) measured in lumbosacral motoneurones. Responses were grouped and averaged according to their timing within ...
Hiraguchi Tetsutaro - - 2003
Mechanoreceptors involved in the escape jumping evoked by hindwing stimulation have been investigated in the field cricket Gryllus bimaculatus. By partial ablation of the hindwing, we found that a mechanosensory system relevant to the escape behaviour was localized on specific veins of the hindwing tip. Scanning electron microscopy revealed three ...
Dau Torsten - - 2003
A model for the generation of auditory brainstem responses (ABR) and frequency following responses (FFRs) is presented. The model is based on the concept introduced by Goldstein and Kiang [J. Acoust. Soc. Am. 30, 107-114 (1958)] that evoked potentials recorded at remote electrodes can theoretically be given by convolution of ...
Chacron Maurice J - - 2003
Neuronal adaptation as well as interdischarge interval correlations have been shown to be functionally important properties of physiological neurons. We explore the dynamics of a modified leaky integrate-and-fire (LIF) neuron, referred to as the LIF with threshold fatigue, and show that it reproduces these properties. In this model, the postdischarge ...
Svirskis Gytis - - 2003
Subthreshold voltage- and time-dependent conductances can subserve different roles in signal integration and action potential generation. Here, we use minimal models to demonstrate how a non-inactivating low-threshold outward current (I(KLT)) can enhance the precision of small-signal integration. Our integrate-and-fire models have only a few biophysical parameters, enabling a parametric study ...
Kalluri Sridhar S Harvard University-Massachusetts Institute of Technology, Division of Health Sciences and Technology, Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA. - - 2003
Onset (On) neurons in the cochlear nucleus (CN), characterized by their prominent response to the onset followed by little or no response to the steady-state of sustained stimuli, have a remarkable ability to entrain (firing 1 spike per cycle of a periodic stimulus) to low-frequency tones up to 1000 Hz. ...
Warzecha A-K - - 2003
Synaptic transmission is usually studied in vitro with electrical stimulation replacing the natural input of the system. In contrast, we analyzed in vivo transfer of visual motion information from graded-potential presynaptic to spiking postsynaptic neurons in the fly. Motion in the null direction leads to hyperpolarization of the presynaptic neuron ...
Bi Guo Qiang - - 2002
Activity-dependent synaptic modification is critical for the development and function of the nervous system. Recent experimental discoveries suggest that both the extent and the direction of modification may depend on the precise timing of pre- and postsynaptic action potentials (spikes). This phenomenon, termed spike timing-dependent plasticity (STDP), provides a new, ...
Bi Guo-Qiang - - 2002
Recent experimental results on spike-timing-dependent plasticity (STDP) and heterosynaptic interaction in various systems have revealed new temporal and spatial properties of activity-dependent synaptic plasticity. These results challenge the conventional understanding of Hebb's rule and raise intriguing questions regarding the fundamental processes of cellular signaling. In this article, I review these ...
Fusi Stefano - - 2002
Synaptic plasticity is believed to underlie the formation of appropriate patterns of connectivity that stabilize stimulus-selective reverberations in the cortex. Here we present a general quantitative framework for studying the process of learning and memorizing of patterns of mean spike rates. General considerations based on the limitations of material (biological ...
Saunders James C - - 2002
Tuning curves, spontaneous activity, and rate-intensity (RI) functions were obtained from units in the chick cochlear nerve. The characteristic frequency (CF) was determined from each tuning curve. The shape of each RI function was subjectively evaluated and assigned to one of four RI types. The breakpoint, discharge rate at the ...
Robinson Hugh P C - - 2002
In cerebral cortex, cells tend to fire in response to strong transient fluctuations in input, produced by synchronous population activity, which reset the precision of firing and erase correlations between prior and future spike times. Here, using experiments and modeling, we study the accumulation of spike time variance in response ...
Wakeling James M - - 2002
The purpose of this study was to identify the frequency, conduction velocity, and wavelength of fast and slow motor unit action potentials (MUAPs) from mixed mammalian muscle. Stimulation and blocking pulses to the sciatic nerve produced varying recruitment patterns (confirmed by force measurements) of fast and slow motor units of ...
Martinez-Conde Susana - - 2002
When images are stabilized on the retina, visual perception fades. During voluntary visual fixation, however, constantly occurring small eye movements, including microsaccades, prevent this fading. We previously showed that microsaccades generated bursty firing in the primary visual cortex (area V-1) in the presence of stationary stimuli. Here we examine the ...
Cattaert Daniel - - 2002
Contrary to orthodromic spikes that are generated in sensory organs and conveyed to CNS, antidromic spikes are generated in the axon terminals of the sensory neurons within the CNS and are conveyed to the peripheral sensory organ. Antidromic discharges are observed in primary afferent neurons of both vertebrates and invertebrates ...
Wiener Matthew C - - 2002
Reliably decoding neuronal responses requires knowing what aspects of neuronal responses are stimulus related, and which aspects act as noise. Recent work shows that spike trains can be viewed as stochastic samples from the rate variation function, as estimated by the time dependent spike density function (or normalized peristimulus time ...
Sosnovtseva O V - - 2002
We study the coexistence of different rhythms in a local network of one inhibitory and two excitatory nerve cells for a wide range of the excitatory synapse strength and of the slow K+-channel conductance. The dynamic features of spike trains in the presence of noise are discussed. It is found ...
Grigg Peter - - 2002
Experiments were done to characterize responses to stretch and to determine what stretch-related mechanical variables are most closely associated with stretch. Cutaneous afferent neurons were recorded using an in vitro preparation of rat hairy skin. SA2 afferents and mechanically sensitive C afferents were studied using static stretch stimuli in which ...
Weeg Matthew S - - 2002
The mechanosensory lateral line of fish is a hair cell based sensory system that detects water motion using canal and superficial neuromasts. The trunk lateral line of the plainfin midshipman fish, Porichthys notatus, only has superficial neuromasts. The posterior lateral line nerve (PLLn) therefore innervates trunk superficial neuromasts exclusively and ...
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