Excitatory Response (excitatory + response)

Distribution by Scientific Domains


Selected Abstracts


Development of Tactile Responses in Human Preterm and Full-Term Infants From 30 to 40 Weeks Postconceptional Age

INFANCY, Issue 1 2002
Isabel Fearon
Maturation of tactile sensitivity prior to term was examined in 36 preterm and 13 full-term infants using a fixed-trial, habituation procedure. Each infant was presented with a series of 8 habituation (arm stroke), 2 novel (arm lift), and 2 recovery (arm stroke) stimulus trials while heart rate and body movements were recorded. Maturation was observed with a gradual increase in the magnitude of the stimulus-elicited cardiac acceleration and cardiac-movement coupling from 30 to 40 weeks postconceptional age. The majority of infants displayed habituation,an excitatory response (heart rate acceleration and body movement),to the initial presentation of a tactile stimulus, response decline with repeated stimulations, and renewed response to a novel stimulus. A substantial number of infants (40%) failed to respond initially to the tactile stimulus, increased responding over several stimulus presentations, and failed to discriminate the presentation of a novel stimulus. We speculate that these differences in response patterns observed over all ages represent individual difference in the perception of stimulus intensity. [source]


Millimeter wave effects on electrical responses of the sural nerve in vivo

BIOELECTROMAGNETICS, Issue 3 2010
Stanislav I. Alekseev
Abstract Millimeter wave (MMW, 42.25,GHz)-induced changes in electrical activity of the murine sural nerve were studied in vivo using external electrode recordings. MMW were applied to the receptive field of the sural nerve in the hind paw. We found two types of responses of the sural nerve to MMW exposure. First, MMW exposure at the incident power density ,45,mW/cm2 inhibited the spontaneous electrical activity. Exposure with lower intensities (10,30,mW/cm2) produced no detectable changes in the firing rate. Second, the nerve responded to the cessation of MMW exposure with a transient increase in the firing rate. The effect lasted 20,40,s. The threshold intensity for this effect was 160,mW/cm2. Radiant heat exposure reproduced only the inhibitory effect of MMW but not the transient excitatory response. Depletion of mast cells by compound 48/80 eliminated the transient response of the nerve. It was suggested that the cold sensitive fibers were responsible for the inhibitory effect of MMW and radiant heat exposures. However, the receptors and mechanisms involved in inducing the transient response to MMW exposure are not clear. The hypothesis of mast cell involvement was discussed. Bioelectromagnetics 31:180,190, 2010. © 2009 Wiley-Liss, Inc. [source]


Evidence that 5-hydroxytryptamine7 receptors play a role in the mediation of afferent transmission within the nucleus tractus solitarius in anaesthetized rats

BRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2009
Diana Oskutyte
Background and purpose:, Central 5-hydroxytryptamine (5-HT)-containing pathways utilizing 5-HT7 receptors are known to be critical for the mediation of cardiovascular reflexes. The nucleus tractus solitarius (NTS) is a site involved in the integration of cardiovascular afferent information. The present experiments examined the involvement of the 5-HT7 receptor in the processing of cardiovascular reflexes in the NTS. Experimental approach:, In anaesthetized rats extracellular recordings were made from 104 NTS neurones that were excited by electrical stimulation of the vagus nerve and/or activation of cardiopulmonary afferents. Drugs were applied ionophoretically in the vicinity of these neurones. Key results:, The non-selective 5-HT7 receptor agonist 5-carboxamidotryptamine maleate (5-CT) applied to 78 neurones increased the firing rate in 18 by 59% and decreased it in 38 neurones by 47%. Similarly, the 5-HT1A agonist 8-OH-DPAT applied to 20 neurones had an excitatory (8), inhibitory (7) or no effect (5) on the 20 neurones tested. In the presence of the 5-HT7 antagonist SB 258719 the 5-CT excitation was attenuated. Furthermore, the excitatory response of NTS neurones evoked by electrical stimulation of the vagus nerve or activation of cardiopulmonary afferents with intra atrial phenylbiguanide was attenuated by SB 258719. The inhibitory action of 5-CT was unaffected by SB 258719 and the 5-HT1A antagonist WAY-100635. WAY-100635 failed to have any effect on 5-CT and vagal afferent-evoked excitations. Conclusions and implications:, Vagal afferent-evoked excitation of NTS neurones can be blocked by SB 258719, a selective 5-HT7 antagonist. This observation further supports the involvement of 5-HT neurotransmission in NTS afferent processing. [source]


ELECTROPHYSIOLOGICAL EVIDENCE FOR THE INTERACTION OF SUBSTANCE P AND GLUTAMATE ON A, AND C AFFERENT FIBRE ACTIVITY IN RAT HAIRY SKIN

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2006
Qi Zhang
SUMMARY 1The purpose of the present study was to investigate whether there was a cooperative interaction between substance P (SP) and glutamate (GLU) administered subcutaneously on A, and C primary afferent fibre activity in dorsal hairy skin of the rat in vivo. The single unit activities of A, and C afferent fibres were recorded by isolation of fibre filaments from the dorsal cutaneous nerve branches and the effects of subcutaneous injections of low doses of SP, GLU and SP + GLU on activity were determined. 2Sub-threshold doses of SP (1 µmol/L, 10 µL) administered subcutaneously into the dorsal hairy skin had no effect on the afferent discharges of either A, or C units. 3The afferent discharges of 35% (11/31) of A, fibres and 33% (6/18) of C fibres were increased by local injection of the submaximal doses of GLU (10 µmol/L, 10 µL) into the receptive fields. 4The GLU-induced excitatory response was significantly enhanced by coinjection of subthreshold doses of SP. The mean discharge rates of A, fibres and C fibres were increased from 5.84 ± 1.54 and 5.02 ± 2.65 impulses/min to 19.91 ± 4.35 and 17.58 ± 5.59 impulses/min, respectively, whereas the excitatory proportions of A, and C fibres were increased from 35 and 33% to 84 and 83%, respectively. The duration of the excitation for A, fibres and C fibres was also significantly increased after coinjection of SP + GLU compared with that observed when either substance was given alone. 5The present study provides electrophysiological evidence for an interaction between receptors for SP and GLU on the fine fibres activities in rat hairy skin, which may be involved in the mechanisms of hyperalgesia. [source]


Multiple functions of GABAA and GABAB receptors during pattern processing in the zebrafish olfactory bulb

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2008
Rico Tabor
Abstract ,-Aminobutyric acid (GABA)ergic synapses are thought to play pivotal roles in the processing of activity patterns in the olfactory bulb (OB), but their functions have been difficult to study during odor responses in the intact system. We pharmacologically manipulated GABAA and GABAB receptors in the OB of zebrafish and analysed the effects on odor responses of the output neurons, the mitral cells (MCs), by electrophysiological recordings and temporally deconvolved two-photon Ca2+ imaging. The blockade of GABAB receptors enhanced presynaptic Ca2+ influx into afferent axon terminals, and changed the amplitude and time course of a subset of MC responses, indicating that GABAB receptors have a modulatory influence on OB output activity. The blockade of GABAA receptors induced epileptiform firing, enhanced excitatory responses and abolished fast oscillations in the local field potential. Moreover, the topological reorganization and decorrelation of MC activity patterns during the initial phase of the response was perturbed. These results indicate that GABAA receptor-containing circuits participate in the balance of excitation and inhibition, the regulation of total OB output activity, the synchronization of odor-dependent neuronal ensembles, and the reorganization of odor-encoding activity patterns. GABAA and GABAB receptors are therefore differentially involved in multiple functions of neuronal circuits in the OB. [source]


Cortical versus spinal dysfunction in amyotrophic lateral sclerosis

MUSCLE AND NERVE, Issue 5 2006
Shahram Attarian MD
Abstract Little is known about the possible link between cortical and spinal motor neuron dysfunction in amyotrophic lateral sclerosis (ALS). We correlated the characteristics of the responses to transcranial magnetic stimulation (TMS) with the electromechanical properties and firing pattern of single motor units (MUs) tested in nine ALS patients, three patients with Kennedy's disease, and 15 healthy subjects. In Kennedy's disease, 19 of 22 MUs were markedly enlarged with good electromechanical coupling and discharged with great variability. Their excitatory responses increased with MU size. In ALS, 17 of 34 MUs with excitatory responses behaved as in Kennedy's disease. By contrast, 28 MUs with nonsignificant responses showed poor electromechanical coupling and high firing rates, whereas 28 MUs with inhibitory responses showed moderate functional alterations. This result indicates that in ALS as in Kennedy's disease, sprouting of corticospinal axons may occur on surviving motoneurons. A clear relationship exists between the responsiveness of MUs to TMS and their functional state. Muscle Nerve, 2006 [source]


Excitatory synaptic inputs on myenteric Dogiel type II neurones of the pig ileum

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2001
Wim Cornelissen
Abstract The synaptic input on myenteric Dogiel type II neurones (n = 63) obtained from the ileum of 17 pigs was studied by intracellular recording. In 77% of the neurones, electrical stimulation of a fibre tract evoked fast excitatory postsynaptic potentials (fEPSPs) with an amplitude of 6 ± 5 mV (mean ± S.D.) and lasting 49 ± 29 ms. The nicotinic nature of the fEPSPs was demonstrated by superfusing hexamethonium (20 ,M). High-frequency stimulation (up to 20 Hz, 3 seconds) did not result in a rundown of the fEPSPs, and did not evoke slow excitatory or inhibitory postsynaptic potentials. The effects of neurotransmitters, possibly involved in these excitatory responses, were investigated. Pressure microejection of acetylcholine (10 mM in pipette) resulted in a fast nicotinic depolarisation in 67%(18/27) of the neurones (13 ± 9 mV, duration 7.0 ± 7.2 seconds) as did 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) application (10 mM; 14 ± 10 mV, duration 4.1 ± 2.8 seconds) in 76%of the cells. The fast nicotinic response to acetylcholine was sometimes (6/27) followed by a slow muscarinic depolarisation (8 ± 4 mV; duration 38.7 ± 10.8 seconds). Immunostaining revealed 5-hydroxytryptamine hydrochloride (5-HT)- and calcitonin gene-related peptide (CGRP)-positive neuronal baskets distributed around and in close vicinity to Dogiel type II neuronal cell bodies. Microejection of 5-HT (10 mM) resulted in a fast nicotinic-like depolarisation (12 ± 6 mV, duration 3.0 ± 1.3 seconds) in 4 of 8 neurones tested, whereas microejection of CGRP (20 mM) gave rise to a slow muscarinic-like depolarisation (6 ± 2 mV, duration 56.0 ± 27.5 seconds) in 8 of 12 neurones tested. In conclusion, myenteric Dogiel type II neurones in the porcine ileum receive diverse synaptic input. Mainly with regard to the prominent presence of nicotinic responses, these neurones behave contrary to their guinea pig counterparts. J. Comp. Neurol. 432:137,154, 2001. © 2001 Wiley-Liss, Inc. [source]