Search Results
Results 551 - 600 of 1344
< 7 8 9 10 11 12 13 14 15 16 17 >
Li Zhen - - 2009
Fire has played an essential role in the development of human civilization. Most previous research suggests that frequent-fire regimes in the late Holocene were associated with intensification of human activities, especially agriculture development. Here, we analyze fire regimes recorded in the Song Hong delta area of Vietnam over the past ...
Griffin L L Department of Kinesiology and Health Education, University of Texas at Austin, Bellmont 222, 1 University Station, D3700, Austin, TX 78712, USA. - - 2009
We compared motor unit synchronization and firing rate variability within and across synergistic hand muscles during a pinching task following short-term light-load training to improve force steadiness in older adults. A total of 183 motor unit pairs before training and 158 motor unit pairs after training were recorded with intramuscular ...
Ojima Hisayuki - - 2010
Some animals are forced to rely more on non-visual signals, such as audition or olfaction, than on vision when a bright environment becomes dark. By recording from a primary-like auditory cortex (field A) in freely moving guinea pigs, possible changes in the responsiveness of single units were explored in association ...
Clemens Béla B Kenézy Hospital Ltd., Department of Neurology, Debrecen, Hungary. - - 2009
Collating the findings regarding the role of focal interictal epileptiform discharges (IEDs) on CNS functions raises the possibility that IEDs might have negative impact that outlasts the duration of the spike-and-wave complexes. The aim of this study was the electrophysiological demonstration of the "delayed effect" of the IEDs. 19-channel, linked-ears ...
Shamir Maoz - - 2009
Sensory processing is associated with gamma frequency oscillations (30-80 Hz) in sensory cortices. This raises the question whether gamma oscillations can be directly involved in the representation of time-varying stimuli, including stimuli whose time scale is longer than a gamma cycle. We are interested in the ability of the system ...
Kobayashi Katsuhiro K Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hospital, Shikatacho 2-chome 5-1, Okayama 700-8558, Japan. - - 2009
A novel type of statistical time-frequency analysis was developed to elucidate changes of high-frequency EEG activity associated with epileptic spikes. The method uses the Gabor Transform and detects changes of power in comparison to background activity using t-statistics that are controlled by the false discovery rate (FDR) to correct type ...
Montano Nicola - - 2009
Neural signals convey information through two different modalities: intensity and discharge pattern. The intensity code is based on the number of action potentials per unit time, which is then easily translated into neurotransmitter release. This kind of information may be assessed simply by counting the number of spikes or bursts ...
Lin John Y JY Department of Pharmacology, University of California, San Diego, California, USA. - - 2009
Channelrhodopsin 2 (ChR2), a light-activated nonselective cationic channel from Chlamydomonas reinhardtii, has become a useful tool to excite neurons into which it is transfected. The other ChR from Chlamydomonas, ChR1, has attracted less attention because of its proton-selective permeability. By making chimeras of the transmembrane domains of ChR1 and ChR2, ...
Damjanović Ilija - - 2009
Responses of direction-selective (DS) ganglion cells (GCs) were recorded extracellularly from their axon terminals in the superficial layer of tectum opticum (TO) of immobilized cyprinid fish Carassius gibelio (Bloch, 1782). Excitatory receptive field (ERF) sizes of six types of DS GCs (ON and OFF cells, each of three distinct preferred ...
Jermakowicz Walter J - - 2009
Coincident spikes have been implicated in vision-related processes such as feature binding, gain modulation, and long-distance communication. The source of these spike-time correlations is unknown. Although several studies have proposed that cortical spikes are correlated based on stimulus structure, others have suggested that spike-time correlations reflect ongoing cortical activity present ...
Peron Simon S Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, - - 2009
How active membrane conductance dynamics tunes neurons for specific time-varying stimuli remains poorly understood. We studied the biophysical mechanisms by which spike frequency adaptation shapes visual stimulus selectivity in an identified visual interneuron of the locust. The lobula giant movement detector (LGMD) responds preferentially to objects approaching on a collision ...
Schreiber Susanne - - 2009
Despite intrinsic noise sources, neurons can generate action potentials with remarkable reliability. This reliability is influenced by the characteristics of sensory or synaptic inputs, such as stimulus frequency. Here we use conductance-based models to study the frequency dependence of reliability in terms of the underlying single-cell properties. We are led ...
Higgs Matthew H - - 2009
The frequency response properties of neurons are critical for signal transmission and control of network oscillations. At subthreshold membrane potential, some neurons show resonance caused by voltage-gated channels. During action potential firing, resonance of the spike output may arise from subthreshold mechanisms and/or spike-dependent currents that cause afterhyperpolarizations (AHPs) and ...
Prescott Steven A SA Howard Hughes Medical Institute, Computational Neurobiology Laboratory, Salk Institute, La Jolla, California 92037, USA. - - 2008
Spike-frequency adaptation causes reduced spiking during prolonged stimulation, but the full impact of adaptation on neural coding is far more complex, especially if one takes into account the diversity of biophysical mechanisms mediating adaptation and the different ways in which neural information can be encoded. Here, we show that adaptation ...
Farina Dario - - 2009
We investigated the changes in muscle fiber conduction velocity, recruitment and derecruitment thresholds, and discharge rate of low-threshold motor units during a series of ramp contractions. The aim was to compare the adjustments in motor unit activity relative to the duration that each motor unit was active during the task. ...
Edds-Walton Peggy L - - 2008
This study is a continuation of a long-term investigation of the auditory circuit in the oyster toadfish, Opsanus tau. Input from the auditory periphery projects to the ipsilateral descending octaval nucleus (DON). Ipsilateral and contralateral DONs project to the auditory midbrain, where a previous study indicated that both frequency tuning ...
Hernández Daniel L - - 2008
Fire can alter a multitude of ecosystem properties that have the potential to affect rates of litter decomposition and nitrogen dynamics. In this study, we examined the effect of long-term variation in fire frequency in Minnesota oak savanna on rates of litter mass loss of a common tree species (Quercus ...
Wei Haoyan - - 2008
Single-wall carbon nanotube (SWNT) nanofibrils were assembled onto a variety of conductive scanning probes including atomic force microscope (AFM) tips and scanning tunnelling microscope (STM) needles using positive dielectrophoresis (DEP). The magnitude of the applied electric field was varied in the range of 1-20 V to investigate its effect on the ...
Crow Terry - - 2008
Ciliary locomotion in the nudibranch mollusk Hermissenda is modulated by the visual and graviceptive systems. Components of the neural network mediating ciliary locomotion have been identified including aggregates of polysensory interneurons that receive monosynaptic input from identified photoreceptors and efferent neurons that activate cilia. Illumination produces an inhibition of type ...
Freeman Walter J - - 2008
Phase slip and beat phenomena are ubiquitous in many forms of wave superposition. Likewise, it is trivially true that cumulative summation of individual random events gives rise to "brown noise" (1/f(2) power spectrum). This paper presents a simulation that relates these phenomena with cortical function. We report that phase interference ...
Farina Dario - - 2008
The study analyses the two-dimensional distribution of surface mechanomyographic (MMG) signal generated by the activation of single motor units located in three transverse positions in the tibialis anterior muscle. In 12 healthy volunteers, surface MMG signals were recorded from the tibialis anterior muscle with a 3 x 4 grid of ...
Prasartwuth Orawan O Department of Physical Therapy, Faculty of Associated Medical Sciences, Chiangmai University, Chiangmai, - - 2008
We have induced H-reflex responses in human tibialis anterior motor units and analysed the results using the classical technique, peristimulus time histogram (PSTH), and a new technique, peristimulus frequencygram (PSF). The PSF has recently been shown to be more reliable than the PSTH for indicating the synaptic connections on motoneurones, ...
Tokutake Yoichiro Y Department of Neuroscience, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104-6058, - - 2008
According to the 'redundancy reduction' hypothesis, a visual neuron removes correlations from an image to reduce redundancy in the spike train, thus increasing the efficiency of information coding. However, all elaborations of this general hypothesis have treated spatial and temporal correlations separately. To investigate how a retinal ganglion cell responds ...
Miller Benjamin R BR Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, 1101 East 10th St., Bloomington, IN 47405, - - 2008
Huntington's disease (HD) is an autosomal dominant condition that compromises behavioral output. Dysfunction of medium spiny neurons (MSNs), which are the sole output system of the striatum, is thought to underlie HD pathophysiology. What is not known is how HD alters MSN information processing during behavior, which likely drives the ...
Ray Supratim S Department of Neurobiology, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA. - - 2008
Neuronal oscillations in the gamma frequency range have been reported in many cortical areas, but the role they play in cortical processing remains unclear. We tested a recently proposed hypothesis that the intensity of sensory input is coded in the timing of action potentials relative to the phase of gamma ...
Freeman Daniel K - - 2008
Action potentials were recorded from rat retinal ganglion cell fibers in the presence of a uniform field, and the maintained discharge pattern was characterized. Spike trains recorded under ketaminexylazine. The majority of cells had multimodal interval distributions, with the first peak in the range of 25.00.97). Both ON and OFF ...
Hupé Ginette J - - 2008
The brown ghost knifefish, Apteronotus leptorhynchus, is a model wave-type gymnotiform used extensively in neuroethological studies. As all weakly electric fish, they produce an electric field (electric organ discharge, EOD) and can detect electric signals in their environments using electroreceptors. During social interactions, A. leptorhynchus produce communication signals by modulating ...
Carlson Bruce A BA Department of Biology, Washington University, St. Louis, MO 63130-4899, USA. - - 2008
In wave-type weakly electric fish, two distinct types of primary afferent fibers are specialized for separately encoding modulations in the amplitude and phase (timing) of electrosensory stimuli. Time-coding afferents phase lock to periodic stimuli and respond to changes in stimulus phase with shifts in spike timing. Amplitude-coding afferents fire sporadically ...
Balaji J J Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, - - 2008
The ability to recycle synaptic vesicles is a crucial property of nerve terminals that allows maintenance of synaptic transmission. Using high-sensitivity optical approaches at hippocampal nerve terminals in dissociated neurons in culture, we show that modulation of endocytosis can be achieved by expansion of the endocytic capacity. Our experiments indicate ...
Gai Yan Y Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, - - 2008
Gai and Carney (J Neurophysiol 96:2451-2464, 2006) previously explored the detection of tones in noise based on responses in the anteroventral cochlear nucleus; that study focused on temporal information in discharge reliability and analyses of neural responses related to the fine structure or envelope of the stimulus. Two additional temporal ...
Belitski Andrei A Max Planck Institute for Biological Cybernetics, D-72076 Tübingen, - - 2008
Local field potentials (LFPs) reflect subthreshold integrative processes that complement spike train measures. However, little is yet known about the differences between how LFPs and spikes encode rich naturalistic sensory stimuli. We addressed this question by recording LFPs and spikes from the primary visual cortex of anesthetized macaques while presenting ...
Duindam Vincent - - 2008
Bevel-tip flexible needles have greater mobility than straight rigid needles, and can be used to reach targets behind sensitive or impenetrable areas. Accurately planning and executing the optimal motions for such steerable needles is difficult, however, and requires solving inverse kinematics for a nonholonomic system.This paper presents an approach to ...
Lasker David M - - 2008
Extracellular recordings were made from vestibular-nerve afferents innervating the semicircular canals in anesthetized C57BL/6 mice ranging in age from 4-24 weeks. A normalized coefficient of variation was used to divide afferents into regular (CV*<0.1) and irregular (CV*>0.1) groups. There were three overall conclusions from this study. First, mouse afferents resemble ...
Mistry Rajen B - - 2008
Transmission through the thalamus activates circuits involving the GABAergic neurons of the thalamic reticular nucleus (TRN). TRN cells receive excitatory inputs from thalamocortical and corticothalamic cells and send inhibitory projections to thalamocortical cells. The inhibitory output of TRN neurons largely depends on the level of excitatory drive to these cells ...
Tolnai Sandra - - 2008
The medial nucleus of the trapezoid body (MNTB) is a distinct nucleus in the superior olivary complex that transforms excitatory input from the cochlear nucleus into a widespread inhibitory output to distinct auditory brainstem nuclei. Few studies have dealt with the response properties of MNTB neurons to sound stimulation using ...
Teslenko Vyacheslav S - - 2008
In the paper the problems of acoustic waves generation of required frequency, amplitude and profile by the phase synchronization of multichannel discharges are considered. The phase synchronization of discharges is supplied by the implementation in the discharge circuit of additional inductance which acts as a dynamic feedback and ensures the ...
Bibikov Nikolay G - - 2008
We explored the statistical properties of the spontaneous and evoked firing activity in the brainstem auditory units of the grass frog (Rana t temporaria). We estimated the properties of spontaneous firing using the following functions: interspike interval distribution, hazard function, autocorrelation functions for original and shifted sequence of interspike intervals, ...
Bibikov N G - - 2008
We recorded extracellular activity from 402 single units located in the inferior colliculus (IC) of barbiturate-anesthetized albino mice. The stimuli were pure tones at characteristic frequency (CF) with durations of 10, 40 and 100 ms and intensities ranged from 5 to 25 dB above unit's minimum threshold (MT). The tones ...
Huxter John R JR MRC Anatomical Neuropharmacology Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, - - 2008
Temporal coding is a means of representing information by the time, as opposed to the rate, at which neurons fire. Evidence of temporal coding in the hippocampus comes from place cells, whose spike times relative to theta oscillations reflect a rat's position while running along stereotyped trajectories. This arises from ...
van Brederode Johannes F M JF Department of Physiology and Biophysics, University of Washington, 1705 NE Pacific St., Harris Hydraulics Rm 309, Box 357290, Seattle, WA 98195-7290, USA. - - 2008
During an inspiration the output of hypoglossal (XII) motoneurons (HMs) in vitro is characterized by synchronous oscillatory firing in the 20- to 40-Hz range. To maintain synchronicity it is important that the cells fire with high reliability and precision. It is not known whether the intrinsic properties of HMs are ...
Bhumbra G S - - 2008
Neural information is conveyed by action potentials along axons to downstream synaptic targets. Synapses permit functionally relevant modulation of the information transmitted by converging inputs. Previous studies have measured the amount of information associated with a given stimulus based either on spike counts or on the relative frequencies of spike ...
Mehaffey W Hamish - - 2008
The tuning of neuronal responsiveness to specific stimulus frequencies is an important computation across many sensory modalities. The weakly electric fish Apteronotus leptorhynchus detects amplitude modulations of a self-generated quasi-sinusoidal electric organ discharge to sense its environment. These fish have to parse a complicated electrosensory environment with a wide range ...
Yasuda Hideaki - - 2008
We investigate a novel class of neural stochastic resonance (SR) exhibiting error-free information transfer. Unlike conventional neural SR, where the decrease of a system's response with too much noise is associated with an increase in the baseline firing rate, here the bell-shaped SR behavior of the input-output cross correlation emerges ...
Dacks A M - - 2008
The nervous system copes with variability in the external and internal environment by using neuromodulators to adjust the efficacy of neural circuits. The role of serotonin (5HT) as a neuromodulator of olfactory information processing in the antennal lobe (AL) of Manduca sexta was examined using multichannel extracellular electrodes to record ...
Nemenman Ilya - - 2008
Sensory information about the outside world is encoded by neurons in sequences of discrete, identical pulses termed action potentials or spikes. There is persistent controversy about the extent to which the precise timing of these spikes is relevant to the function of the brain. We revisit this issue, using the ...
Hofmann M H - - 2008
Paddlefish use their peculiar rostrum to detect minute electric fields from their main prey, small water fleas. Electroreceptors over the rostrum and head sense these fields and send the information into a single hindbrain area, the dorsal octavolateral nucleus (DON). From there, information is sent to various midbrain structures, including ...
Gollisch Tim - - 2008
Natural vision is a highly dynamic process. Frequent body, head, and eye movements constantly bring new images onto the retina for brief periods, challenging our understanding of the neural code for vision. We report that certain retinal ganglion cells encode the spatial structure of a briefly presented image in the ...
Masse Nicolas Y - - 2008
Previous studies have shown that sensory neurons that are the most informative of the stimulus tend to be the best correlated with the subject's perceptual decision. We wanted to know whether this relationship might also apply to short time segments of a neuron's response. We asked whether spikes that conveyed ...
Wang Ying - - 2008
By simultaneously recording the activity of individual neurons and field potentials in freely behaving mice, we found two types of interneurons firing at high frequency in the hippocampal CA1 region, which had high correlations with characteristic sharp wave-associated ripple oscillations (100-250 Hz) during slow-wave sleep. The firing of these two ...
Curti Sebastián - - 2008
Primary auditory afferents are generally perceived as passive, timing-preserving lines of communication. Contrasting this view, identifiable auditory afferents to the goldfish Mauthner cell undergo potentiation of their mixed--electrical and chemical--synapses in response to high-frequency bursts of activity. This property likely represents a mechanism of input sensitization because they provide the ...
< 7 8 9 10 11 12 13 14 15 16 17 >