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Transducer properties of the rapidly adapting stretch receptor neurone in the crayfish (Pacifastacus leniusculus).

Rydqvist, B; Purali, N
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1993 Português
Relevância na Pesquisa
26.62%
1. The transducer properties of the rapidly adapting stretch receptor neurone of the crayfish (Pacifastacus leniusculus) were studied using a two-microelectrode voltage clamp technique. 2. The impulse response to ramp-and-hold extensions of the receptor muscle typically consisted of a high frequency burst followed by cessation of impulses within a relatively short time depending on the amplitude of extension. The type of adaptation was consistent with earlier studies. The stimulus-response relationship for the impulse frequency was non-linear and had a slope in a log-log plot of 2.9. 3. When impulse generation was blocked by tetrodotoxin (TTX), (block of Na+ channels) the receptor potential was extension dependent and similar to that found in the slowly adapting receptor. For small extensions there was an initial peak followed by a fall to a steady potential level. For large extensions the potential response during the ramp phase consisted of a peak followed by a constant potential level lasting to the end of the ramp. When the extension changed to the hold phase the potential fell towards a steady state. The relation between extension and amplitude of receptor potential was non-linear and saturated at -40 to -30 mV (extensions > 15% of zero length...

Velocity sensitivity of human muscle spindle afferents and slowly adapting type II cutaneous mechanoreceptors.

Grill, S E; Hallett, M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/12/1995 Português
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26.75%
1. Velocity information is used in the performance of movement. This study evaluated the ability of peripheral receptors to signal velocity in human subjects. 2. The velocity sensitivity of human muscle spindle afferents from the extensor digitorum muscles and slowly adapting type II cutaneous mechanoreceptors on the dorsum of the hand was evaluated with recordings from the radial nerve during imposed flexion movements about the metacarpophalangeal joint. Twenty-degree movements at velocities ranging from 5 to 80 deg s-1 were used. 3. Three measures of dynamic response were calculated: the dynamic positional sensitivity (the relation between discharge rate and joint angle during the dynamic phase of movement), the dynamic index (the discharge rate just before ramp completion minus the rate 0.5 s later), and the incremental response (the discharge rate just before ramp completion minus the rate just before ramp onset). 4. Both muscle spindle afferents and slowly adapting type II cutaneous mechanoreceptors demonstrated significant velocity sensitivity. The magnitudes of the relations between dynamic response measures and velocity were similar in the two receptor types. 5. These findings are consistent with the view that both muscle spindle afferents and slowly adapting type II cutaneous mechanoreceptors provide reasonable velocity signals.

Lung congestion augments the responses of cells in the rapidly adapting receptor pathway to cigarette smoke in rabbit.

Zhang, Z; Bonham, A C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/04/1995 Português
Relevância na Pesquisa
26.62%
1. We examined the effects of cigarette smoke, inhaled alone and during mild pulmonary venous congestion, on the activity of fifty-three neurones in the nucleus tractus solitarii (NTS) that were excited by input from pulmonary rapidly adapting receptors (RAR). Ten neurones excited by slowly adapting stretch receptors (SAR) were also studied. 2. Extracellular recordings of RAR-activated neurones were recorded in alpha-chloralose anaesthetized rabbits. Smoke from low- and high-nicotine cigarettes was delivered through a ventilator. Mild pulmonary venous congestion was produced by inflating a balloon in the left atrium. 3. Inhalation of three breaths of smoke from low-nicotine cigarettes increased the activity of fifty-one out of fifty-three RAR-activated neurones from 5.9 +/- 1.0 to 14.4 +/- 2.1 spikes breath-1 (P < 0.05). 4. The responses of fifteen neurones were compared with smoke inhaled alone or during mild pulmonary venous congestion. Smoke alone increased unit activity from 6.8 +/- 2.3 to 12.6 +/- 3.7 spikes breath-1 (P < 0.05). Small increases in left atrial pressure (2.0 +/- 0.5 mmHg) had no effect on baseline unit activity (7.6 +/- 2.11 vs. 7.7 +/- 2.3 spikes breath-1; P > 0.05), but enhanced the responses to smoke, increasing the activity from 7.6 +/- 2.1 to 17.1 +/- 4.8 spikes breath-1 (P < 0.05). The response was greater than to smoke alone (P < 0.05). 5. Of ten SAR-activated neurones...

Identification of vagal sensory receptors in the rat lung: are there subtypes of slowly adapting receptors?

Bergren, D R; Peterson, D F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1993 Português
Relevância na Pesquisa
26.62%
1. We studied the characteristics of pulmonary sensory receptors whose afferent fibres are in the left vagus nerve of opened-chest rats. The activity of these receptors was recorded during mechanical ventilation approximating eupnoea, as well as during deflation, stepwise inflations and constant-pressure inflations of the lungs. Data were also collected from closed-chest rats and analysed separately. 2. Ninety-four per cent of receptors were located in the ipsilateral lung or airways with the remainder in the contralateral lung. 3. Not only were slowly adapting receptors (SARs) the most abundant pulmonary receptors but 21% of them were either exclusively or predominantly active during the deflationary phase of the ventilatory cycle. Deflationary units were found in opened- and closed-chest rats. The average conduction velocity for all fibres innervating SARs averaged 29.7 m s-1. 4. We found rapidly adapting receptors (RARs) to be extremely rare in the rat. Their activity was sparse and irregular. The conduction velocities of fibres innervating RARs averaged 12.3 m s-1. 5. Far more abundant than RARs in the remaining population of pulmonary fibres were C fibres. They were observed to have an average conduction velocity of 2.1 m s-1...

Responses of slowly and rapidly adapting receptors in the airways of rabbits to changes in the Starling forces.

Hargreaves, M; Ravi, K; Kappagoda, C T
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1991 Português
Relevância na Pesquisa
26.62%
1. The responses of the rapidly adapting receptors (RARs) and the slowly adapting receptors (SARs) of the airways to changes in the Starling forces regulating fluid exchange in the pulmonary extravascular space were investigated in anaesthetized rabbits. The hydrostatic pressure in the pulmonary microvasculature was raised by partial obstruction of the mitral valve (mean left atrial pressure increased by approximately 5 and 10 mmHg above the control values) and the concentration of plasma proteins was reduced by plasmapheresis (the total plasma protein concentration reduced by 18%). 2. There was a significant correlation between the action potentials generated by RARs and mean left atrial pressure (n = 12). A similar response was not observed in SARs (n = 12). 3. After plasmapheresis, there was an increase in the resting activity of the RARs (n = 5). In addition, the stimulus-response curve relating mean left atrial pressure and RAR activity was significantly shifted to the left compared to the one elicited before plasmapheresis. Plasmapheresis failed to influence the activity of SARs (n = 5). 4. Obstruction of the pulmonary lymph flow by raising the afterload in the right external jugular vein caused a significant increase in the activity of RARs (n = 6). This response was also maintained during the entire period of lymphatic obstruction. 5. The results show that manipulation of the Starling forces within the lung influences the RAR activity profoundly. It is suggested that the stimulus for the RARs may be a function of the fluid fluxes in the pulmonary extravascular space.

Transmembrane ion balance in slowly and rapidly adapting lobster stretch receptor neurones.

Edman, A; Gestrelius, S; Grampp, W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1986 Português
Relevância na Pesquisa
26.83%
The transmembrane exchange of Na+, K+, and Cl- in slowly and rapidly adapting lobster stretch receptor neurones was studied using ion-sensitive microelectrodes in combination with conventional electrophysiological techniques. The investigation was founded on the assumption that the transmembrane ion exchange is accomplished by active and passive transports which add up to zero in steady state for each ion involved. The active transports are assumed to include Na+ and K+ transports driven by an electrogenic Na-K pump. To these transports are also added equimolar fluxes of K+ and Cl- leaking from the impaling micro-electrode. The passive transports are assumed to pass through membrane channels in accordance with constant field kinetics. For a quantitative evaluation of the transmembrane ion exchange in resting conditions measurements were made of the resting concentrations of Na+, K+ and Cl-; the voltage dependence of the ungated leak current; and ouabain-induced changes in resting membrane current and intracellular ion concentrations. From the results it follows that both the resting pump current and the leak permeabilities for the ions investigated have values which do not seem to differ between slowly and rapidly adapting receptor neurones. For a quantitative evaluation of the relation between internal Na+ and pump current production...

Plasmapheresis affects responses of slowly and rapidly adapting airway receptors to pulmonary venous congestion in dogs.

Kappagoda, C T; Ravi, K
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1989 Português
Relevância na Pesquisa
26.62%
1. The effects of plasmapheresis on the responses of rapidly adapting receptors (RARs) and slowly adapting receptors (SARs) of the airways to pulmonary venous congestion were examined in dogs anaesthetized with alpha-chloralose. Pulmonary venous congestion was produced in a graded manner by partial obstruction of the mitral valve sufficient to raise the mean left atrial pressure by 5, 10 and 15 mmHg. Plasmapheresis was performed by withdrawing 10% of blood volume twice. 2. Both RARs (n = 11) and SARs (n = 5) responded to pulmonary venous congestion by increasing their activities. The responses of the former were proportionately greater. 3. After plasmapheresis which reduced the concentration of plasma proteins by 12.3 +/- 1.0%, the responses of the RARs to pulmonary venous congestion were enhanced significantly. There was no significant change in the responses of SARs. 4. In another set of six RARs, the effects of graded pulmonary venous congestion were investigated twice with an interval of 45 min between the two observations. No significant differences were noted between the two responses. 5. Collection of lymph from the tracheobronchial lymph duct (n = 6) showed that after plasmapheresis, there was an increase in the control lymph flow. In addition...

Acute effects of neomycin on slowly adapting type I and type II cutaneous mechanoreceptors in the anaesthetized cat and rat.

Baumann, K I; Hamann, W; Leung, M S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1990 Português
Relevância na Pesquisa
26.62%
1. Slowly adapting type I (SAI) and type II (SAII) mechanoreceptors in the skin were studied in anaesthetized cats and rats employing mechanical stimuli every 30 s. Individual stimuli rose within 200 ms to a plateau force which was kept constant through a feedback control unit for 2000 ms. 2. In cats, close arterial infusion of neomycin (2.5 mg/min) as sulphate was given through a side branch into the femoral blood stream for 5, 10 or 20 min at a rate of 0.025 ml/min. At other times saline was infused at the same rate. 3. After 20 min of neomycin infusion (total 50 mg) nervous discharge of cat SAI receptors was suppressed to about 30% of the control responses before neomycin infusion. Nervous responses were reduced more profoundly during the plateau phase of stimulation than during the dynamic phase. The interspike interval histogram was severely distorted. 4. In contrast, cat SAII receptors maintained about 70% of their control response after 20 min of neomycin infusion. The interspike interval histogram showed an orderly shift towards longer intervals maintaining its normal shape. 5. In rats, intradermal microinfusion of neomycin (30 micrograms/min) through a glass micropipette into the immediate vicinity of the receptor under investigation resulted in severe transient suppression of SAI receptor responses to about 10% of the control level. Receptor responses recovered almost completely about 1 h after the end of neomycin application. 6. It is concluded that the observed differences between the two types of slowly adapting mechanoreceptors are consistent with the hypothesis that the SAI receptor functions as a secondary sensory receptor...

Facilitation of individual gamma-motoneurones by the discharge of single slowly adapting type 1 mechanoreceptors in cats.

Davey, N J; Ellaway, P H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1989 Português
Relevância na Pesquisa
26.89%
1. Cross-correlation of the discharges of individual neurones has been used to investigate the influence of identified cutaneous afferents on gamma-motoneurones below the level of complete spinal section in decerebrated cats. Discharges of single, sural nerve afferents from the heel were recorded in the dorsal root ganglia. Discharges of gamma-motoneurones were recorded from cut filaments of the muscle nerve to gastrocnemius medialis of the same leg. gamma-Motoneurones had a background discharge in the absence of intentional stimulation. 2. Correlograms involving slowly adapting afferents were formed during steady application of a probe to the receptive field for repeated periods of 10 s. Afferent synchronization was minimized by rejecting any period of probe movement. Correlograms involving rapidly adapting afferents required continuous movement of the probe to sustain afferent discharge. 3. Statistically significant primary peaks in correlations were observed for twenty-one pairings of gamma-motoneurones with seventeen out of thirty-nine slowly adapting, type 1 (SA1) mechanoreceptors. Primary peaks had widths at half-maximum in the range of 2-7 ms. No such short duration peaks were seen for fourteen pairings of gamma-motoneurones with eleven slowly adapting type 2 (SA2) receptors or for thirty-five pairings with twenty-nine hair follicle (HF) afferents. Broad correlations with peaks extending over tens of milliseconds were seen for HF afferents and could be generated in correlograms for slowly adapting afferents by moving the probe. 4. The short duration peaks were delayed with respect to the SA1 afferent discharges. Subtraction of peripheral conduction times gave central delays for the increased probability of gamma-motoneurone firing ranging from 2.7 to 6.5 ms (mean = 4.0 ms). These values were not significantly different from the central delays of gamma-motoneurone excitation in response to electrical stimulation of the sural nerve at a strength 1.2 times threshold. 5. The increase in probability of gamma-motoneurone discharge given a single SA1 afferent discharge ranged from 0.005 to 0.156 with a mean value of 0.052. The rise time of the peak ranged from 1 to 4 ms with a mean value of 1.9 ms (n = 9). 6. The properties of the correlogram peaks were not related to the axon conduction velocity of either the SA1 afferent or gamma efferent neurones. 7. The SA1 afferents that facilitated gamma-motoneurone discharge had axon conduction velocities in the range 29-81 m/s and could not be distinguished from SA1 afferents lacking correlations.(ABSTRACT TRUNCATED AT 400 WORDS)

The nature of the receptor mediating stimulant effects of histamine on rapidly adapting vagal afferents in the lungs.

Sampson, S R; Vidruk, E H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1979 Português
Relevância na Pesquisa
26.89%
1. The effects of histamine H1- and H2-agonists on these airway sensory receptors were also examined. 2. Neither I.V. infusion of metiamide (5 mg/kg, min for 35 min) in seven experiments, nor I.V. bolus injection of burimamide (15 mg/kg) in six other experiments, both substances being H2-antagonists, altered the response of rapidly adapting receptors to aerosols of histamine (from 0.1 or 1.0% solutions). 3. Chlorpheniramine (H1-antagonist), 2--5 mg/kg, I.V., completely abolished responses of rapidly adapting receptors to histamine in seven experiments in which metiamide had been given previously and in seven other preparations in which it had not, but had no effect on responses to prostaglandin F2 alpha. Chlorpheniramine itself caused a brief stimulation of rapidly adapting receptors. 4. The H2-agonist S-[3-(N,N-dimethylamino) propyl] isothiourea (Dimaprit), given as aerosol (1% solution for 2 min) or I.V. (2 mg/kg), was without effect on activity of four airway rapidly adapting receptors. These receptors were stimulated, however, by the H1-agonist 2,(2 pyridylethylamine) dihydrochloride (PEA), administered both as aerosol (from a 10% solution) and I.V. (0.4--2 mg/kg). These stimulant effects were abolished by chlorpheniramine. 5. The results indicate that stimulation of airway rapidly adapting receptors by histamine is mediated by histamine H1-receptors.

Excitation and desensitization of mouse rod photoreceptors in vivo following bright adapting light

Kang Derwent, Jennifer J; Qtaishat, Nasser M; Pepperberg, David R
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em 15/05/2002 Português
Relevância na Pesquisa
26.98%
Electroretinographic (ERG) methods were used to determine response properties of mouse rod photoreceptors in vivo following adapting illumination that produced a significant extent of rhodopsin bleaching. Bleaching levels prevailing at ∼10 min and ∼20 min after the adapting exposure were on average 14% and 9%, respectively, based on the analysis of visual cycle retinoids in the eye tissues. Recovery of the rod response to the adapting light was monitored by analysing the ERG a-wave response to a bright probe flash presented at varying times during dark adaptation. A paired-flash procedure, in which the probe flash was presented at defined times after a weak test flash of fixed strength, was used to determine sensitivity of the rod response to the test flash. Recovery of the response to the adapting light was 80% complete at 13.5 ± 3.0 min (mean ± s.d.; n = 7) after adapting light offset. The adapting light caused prolonged desensitization of the weak-flash response derived from paired-flash data. By comparison with results obtained in the absence of the adapting exposure, desensitization determined with a test-probe interval of 80 ms was ∼fourfold after 5 min of dark adaptation and ∼twofold after 20 min. The results indicate...

The Regularity of Sustained Firing Reveals Two Populations of Slowly Adapting Touch Receptors in Mouse Hairy Skin

Wellnitz, Scott A.; Lesniak, Daine R.; Gerling, Gregory J.; Lumpkin, Ellen A.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.83%
Touch is initiated by diverse somatosensory afferents that innervate the skin. The ability to manipulate and classify receptor subtypes is prerequisite for elucidating sensory mechanisms. Merkel cell–neurite complexes, which distinguish shapes and textures, are experimentally tractable mammalian touch receptors that mediate slowly adapting type I (SAI) responses. The assessment of SAI function in mutant mice has been hindered because previous studies did not distinguish SAI responses from slowly adapting type II (SAII) responses, which are thought to arise from different end organs, such as Ruffini endings. Thus we sought methods to discriminate these afferent types. We developed an epidermis-up ex vivo skin–nerve chamber to record action potentials from afferents while imaging Merkel cells in intact receptive fields. Using model-based cluster analysis, we found that two types of slowly adapting receptors were readily distinguished based on the regularity of touch-evoked firing patterns. We identified these clusters as SAI (coefficient of variation = 0.78 ± 0.09) and SAII responses (0.21 ± 0.09). The identity of SAI afferents was confirmed by recording from transgenic mice with green fluorescent protein–expressing Merkel cells. SAI receptive fields always contained fluorescent Merkel cells (n = 10)...

The Formative Method for Adapting Psychotherapy (FMAP): A community-based developmental approach to culturally adapting therapy

Hwang, Wei-Chin
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/2009 Português
Relevância na Pesquisa
26.83%
How do we culturally adapt psychotherapy for ethnic minorities? Although there has been growing interest in doing so, few therapy adaptation frameworks have been developed. The majority of these frameworks take a top-down theoretical approach to adapting psychotherapy. The purpose of this paper is to introduce a community-based developmental approach to modifying psychotherapy for ethnic minorities. The Formative Method for Adapting Psychotherapy (FMAP) is a bottom-up approach that involves collaborating with consumers to generate and support ideas for therapy adaptation. It involves 5-phases that target developing, testing, and reformulating therapy modifications. These phases include: (a) generating knowledge and collaborating with stakeholders (b) integrating generated information with theory and empirical and clinical knowledge, (c) reviewing the initial culturally adapted clinical intervention with stakeholders and revising the culturally adapted intervention, (d) testing the culturally adapted intervention, and (e) finalizing the culturally adapted intervention. Application of the FMAP is illustrated using examples from a study adapting psychotherapy for Chinese Americans, but can also be readily applied to modify therapy for other ethnic groups.

An Efficient and Self-Adapting Localization in Static Wireless Sensor Networks

Teng, Guodong; Zheng, Kougen; Dong, Wei
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 04/08/2009 Português
Relevância na Pesquisa
26.83%
Localization is one of the most important subjects in Wireless Sensor Networks (WSNs). To reduce the number of beacons and adopt probabilistic methods, some particle filter-based mobile beacon-assisted localization approaches have been proposed, such as Mobile Beacon-assisted Localization (MBL), Adapting MBL (A-MBL), and the method proposed by Hang et al. Some new significant problems arise in these approaches, however. The first question is which probability distribution should be selected as the dynamic model in the prediction stage. The second is whether the unknown node adopts neighbors’ observation in the update stage. The third is how to find a self-adapting mechanism to achieve more flexibility in the adapting stage. In this paper, we give the theoretical analysis and experimental evaluations to suggest which probability distribution in the dynamic model should be adopted to improve the efficiency in the prediction stage. We also give the condition for whether the unknown node should use the observations from its neighbors to improve the accuracy. Finally, we propose a Self-Adapting Mobile Beacon-assisted Localization (SA-MBL) approach to achieve more flexibility and achieve almost the same performance with A-MBL.

Chromatic discrimination: differential contributions from two adapting fields

Cao, Dingcai; Lu, Yolanda H.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/02/2012 Português
Relevância na Pesquisa
26.98%
To test whether a retinal or cortical mechanism sums contributions from two adapting fields to chromatic discrimination, L/M discrimination was measured with a test annulus surrounded by an inner circular field and an outer rectangular field. A retinal summation mechanism predicted that the discrimination pattern would not change with a change in the fixation location. Therefore, the fixation was set either in the inner or the outer field in two experiments. When one of the adapting fields was “red” and the other was “green,” the adapting field where the observer fixated always had a stronger influence on chromatic discrimination. However, when one adapting field was “white” and the other was red or green, the white field always weighted more heavily than the other adapting field in determining discrimination thresholds, whether the white field or the fixation was in the inner or outer adapting field. These results suggest that a cortical mechanism determines the relative contributions from different adapting fields.

Adapting research-tested computerized tailored interventions for broader dissemination and implementation

Vinson, Cynthia; Bickmore, Timothy; Farrell, David; Campbell, Marci; An, Larry; Saunders, Ed; Nowak, Mike; Fowler, Betsy; Shaikh, Abdul R
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.75%
This paper focuses on the process for adapting existing legacy computerized tailored intervention (CTI) programs and implications for future development of CTI to ensure that interventions can be disseminated and implemented in different settings. A significant amount of work is required to adapt existing CTI for new research applications and public health interventions. Most new CTI are still developed from scratch, with minimal re-use of software or message content, even when there are considerable overlaps in functionality. This is largely a function of the substantial technical, organizational, and content-based barriers to adapting and disseminating CTI. CTI developers should thus consider dissemination and re-use early in the design phase of their systems. This is not intended to be a step-by-step guide on how to adopt or disseminate research-tested CTI, but rather a discussion that highlights issues to be considered for adapting and disseminating evidence-based CTI.

The specificity of stimulus-specific adaptation in human auditory cortex increases with repeated exposure to the adapting stimulus

Briley, Paul M.; Krumbholz, Katrin
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.75%
The neural response to a sensory stimulus tends to be more strongly reduced when the stimulus is preceded by the same, rather than a different, stimulus. This stimulus-specific adaptation (SSA) is ubiquitous across the senses. In hearing, SSA has been suggested to play a role in change detection as indexed by the mismatch negativity. This study sought to test whether SSA, measured in human auditory cortex, is caused by neural fatigue (reduction in neural responsiveness) or by sharpening of neural tuning to the adapting stimulus. For that, we measured event-related cortical potentials to pairs of pure tones with varying frequency separation and stimulus onset asynchrony (SOA). This enabled us to examine the relationship between the degree of specificity of adaptation as a function of frequency separation and the rate of decay of adaptation with increasing SOA. Using simulations of tonotopic neuron populations, we demonstrate that the fatigue model predicts independence of adaptation specificity and decay rate, whereas the sharpening model predicts interdependence. The data showed independence and thus supported the fatigue model. In a second experiment, we measured adaptation specificity after multiple presentations of the adapting stimulus. The multiple adapters produced more adaptation overall...

S-cone discrimination in the presence of two adapting fields: data and model

Cao, Dingcai
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/04/2014 Português
Relevância na Pesquisa
27.01%
This study investigated S-cone discrimination using a test annulus surrounded by an inner and outer adapting field with systematic manipulation of the adapting l = L/(L + M) or s = S/(L + M) chromaticities. The results showed that different adapting l chromaticities altered S-cone discrimination for a high adapting s chromaticity due to parvocellular input to the koniocellular pathway. In addition, S-cone discrimination was determined by the combined spectral signals arising from both adapting fields. The “white” adapting field or an adapting field with a different l chromaticity from the other fields was more likely to have a stronger influence on discrimination thresholds. These results indicated that the two cardinal axes are not independent in S-cone discrimination, and the two adapting fields jointly contribute to S-cone discrimination through a cortical summation mechanism.

Novel Fast Adapting Interneurons Mediate Cholinergic-Induced Fast GABAA IPSCs In Striatal Spiny Neurons

Faust, Thomas W.; Assous, Maxime; Shah, Fulva; Tepper, James M.; Koós, Tibor
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.83%
Previous work suggests that neostriatal cholinergic interneurons control the activity of several classes of GABAergic interneurons through fast nicotinic receptor mediated synaptic inputs. Although indirect evidence has suggested the existence of several classes of interneurons controlled by this mechanism only one such cell type, the neuropeptide-Y expressing neurogliaform neuron, has been identified to date. Here we tested the hypothesis that in addition to the neurogliaform neurons that elicit slow GABAergic inhibitory responses, another interneuron type exists in the striatum that receives strong nicotinic cholinergic input and elicits conventional fast GABAergic synaptic responses in projection neurons. We obtained in vitro slice recordings from double transgenic mice in which Channelrhodopsin-2 was natively expressed in cholinergic neurons and a population of serotonin receptor-3a-Cre expressing GABAergic interneurons were visualized with tdTomato. We show that among the targeted GABAergic interneurons a novel type of interneuron, termed the fast-adapting interneuron, can be identified that is distinct from previously known interneurons based on immunocytochemical and electrophysiological criteria. We show using optogenetic activation of cholinergic inputs that fast-adapting interneurons receive a powerful supra-threshold nicotinic cholinergic input in vitro. Moreover...

Projections from Pacinian corpuscles and rapidly adapting mechanoreceptors of glabrous skin to the cat's spinal cord.

Brown, A G; Fyffe, R E; Noble, R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1980 Português
Relevância na Pesquisa
26.75%
1. Single axons innervating Pacinian corpuscles and rapidly adapting mechanoreceptors of the foot and toe pads were injected with horseradish peroxidase near their entrance to the lumbosacral spinal cord in cats anaesthetized with chloralose and paralysed with gallamine triethiodide. Subsequent histochemistry revealed the morphology of the intra-spinal parts of the axons. 2. All Pacinian corpuscle axons that could be traced into the dorsal root bifurcated upon entering the cord into ascending and descending branches. All Pacinian corpuscle axons gave rise to collaterals that entered the dorsal horn. 3. The collaterals of Pacinian corpuscle afferent fibres had a distinctive morphology. They provided two regions of termination, a larger dorsal region in laminae III and IV and a smaller ventral region in laminae V and VI. Within the dorsal region the terminal axons ran mainly in the longitudinal axis of the cord and carried many boutons en passant. Within the ventral region the axons ran dorso-ventrally in the transverse plane of the cord and although carrying some boutons en passant also gave rise to clusters of boutons. 4. The collaterals of rapidly adapting afferent fibres had a distinctive morphology different from that of the Pacinian corpuscle afferent fibre collaterals. The termination region of rapidly adapting afferents was limited almost exclusively to lamina III...