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Results for “bimodal stimulation”

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At least 19 recordsLinked to original sources

PubMed2026

Neuromodulation for Subjective Tinnitus: A Systematic Review and Meta-Analysis of Randomized Trials.

OBJECTIVE: To evaluate the effectiveness and safety of neuromodulation and bimodal stimulation for chronic subjective tinnitus in randomized controlled trials (RCTs). DATA SOURCES: PubMed/MEDLINE, Web of Science, and EMBASE (January 2015-December 2025) searched per PRISMA 2020. REVIEW METHODS: Adult RCTs (≥ 18 years) with chronic subjective tinnitus (> 3 months) assessing validated outcomes (THI, TFI, TQ) for neuromodulation/bimodal interventions vs. sham/controls. Two-stage screening, Cochrane RoB-2 risk-of-bias assessment. Random-effects meta-analyses (REML) were performed when ≥ 3 comparable trials were available; effects reported as standardized mean differences (SMD) with 95% CIs. Main Outcomes and measures included change in tinnitus severity (THI/TFI/TQ) while secondary outcomes included loudness (VAS/NRS), durability, and adverse events. RESULTS: Twenty-six RCTs (n = 1576) met criteria: tES (11; n = 372), rTMS (8; n = 432), acoustic coordinated reset (1; n = 100), vagus nerve stimulation (2; n = 90), and bimodal stimulation (4; n = 582). Meta-analysis showed a nonsignificant pooled effect for tDCS (SMD -0.36; 95% CI -0.75 to 0.02; I 2 = 51%) and rTMS (SMD -0.15; 95% CI -0.37 to 0.07; I 2 = 0%). Single-trial evidence for coordinated reset showed no advantage over broadband noise. VNS demonstrated modest benefits with safety concerns limited to implanted approaches. Bimodal stimulation yielded consistent, clinically meaningful reductions (often ≥ 10-20 points on THI/TFI), with durability up to 12 months. Adverse events were mild/transient across noninvasive modalities. CONCLUSIONS: Noninvasive neuromodulation appears safe with average benefits; among modalities, bimodal stimulation shows the most consistent and durable clinical improvements. Standardized, adequately powered RCTs with harmonized protocols and long-term follow-up are needed to refine targets and dosing.

Humans↗

PubMed1976

The role of cutaneous mechanoreceptors in thermal sensation and pain.

The functional behavior of slowly adapting cutaneous mechanoreceptors under combined thermal-mechanical stimulation was investigated by single-unit recordings from the lumbar dorsal roots of the cat. Increased sensitivity to bimodal stimulation was observed in 24 of the 28 units studied, employing stimulus-response functional behavior as the basis for judgment. Low-threshold receptors generally did not exhibit increased spontaneous firing as accompaniment to heightened sensitivity, while such enhanced basal activity was usually observed in moderate-threshold units in addition to increased reactivity. Information theory calculations performed on these stimulus-response data revealed that 15 of the 24 "heat-sensitive" receptors were additionally characterized by an enhanced ability to transmit neural information under bimodal stimulation. These results were interpreted as supporting pattern theories of pain as opposed to the concept of receptor specificity. No contradiction was observed, however, between the present results and those of other investigators. The present conclusions derive from new criteria for thermal reactivity based upon innovative stimulus conditions.

Animals↗

PubMed1975

[Interaction of the visceral and musculocutaneous afferent systems in the secondary somatosensory zone of the cat cerebral cortex].

The convergence of visceral and somatic afferent systems in the secondary somatosensory areas of the cat cortex was studied by means of evoked potentials. The suprathreshold stimulation of the sciatic and brachial plexus nerves depressed the test potentials evoked by the pelvic and mesenteric nerves stimulation. Maximal depression was observed at paired stimulation of visceral nerves. Comparison of the data obtained with mono- and bimodal stimulation suggests that duration of the response restoration period depends on the functional groups of neurons.

Animals↗

PubMedDate not supplied

[Trace processes in the neuronal activity of the rabbit cerebral cortex following rhythmic photic and electrocutaneous stimulation].

Trace unit activity in the visual and sensorimotor cortical areas was studied in alert rabbits after photic and electro-cutaneous stimulation. The ability of the sensorimotor area to preserve temporal stimulation pattern in the afteraction interval was higher than that of the visual area. Maximal rhythm preservation and a higher level of distant correlation in cortical unit activity were seen after synchronous bimodal stimulation. The data obtained suggest some diversity of the mechanisms of trace and evoked activity of cortical neurones.

Animals↗

PubMed1992

Prostaglandin E2 can bimodally inhibit and stimulate the epididymal adipocyte adenylyl cyclase activity.

Measurements of prostaglandin E2 (PGE2)-induced adenylyl cyclase activity in membranes isolated from epididymal rat adipocytes revealed inhibition of cAMP production at low concentrations of PGE2 (less than 10 mM) and stimulation at higher concentrations. This biphasic effect of PGE2 was obtained when adenylyl cyclase was stimulated with GTP or NaF. In the presence of forskolin only the inhibitory phase by PGE2 was observed. Sulprostone, a PGE2 analogue, did not affect cAMP synthesis in the presence of either GTP or NaF; however, in the presence of forskolin, it inhibited cAMP production similarly to PGE2. Treatment of the membranes with cholera or pertussis toxin did not alter the biphasic effect of PGE2 on cAMP production. These findings raise the possibility that PGE2 acts through several receptor subtypes which are coupled to GTP binding proteins different from the classical Gi or Gs proteins.

Adenylate Cyclase Toxin↗

PubMed1979

The effect of brief vagal stimulation on the isolated rabbit sinus node.

We developed an isolated rabbit atrial preparation which responds consistently and reproducibly to brief, submaximal stimulation of the autonomic nerves contained in it. In 6 of 11 preparations in the presence of propranolol (1 mg/liter), the time course of changes in the atrial rate following 120 msec vagal stimulation was bimodal. The maximal slowing occurred at 0.64 +/- 0.16 second, and the peak secondary slowing occurred at 2.3 +/- 1.0 seconds. An acceleratory component occurred between the first and second peaks between 0.8 and 1.6 seconds. The total time course of vagal effect lasted for 5.0 +/- 2.0 seconds. These changes in rate could not be explained by shifts in the location of the primary pacemaker. The acceleratory component was due to a 4.7 +/- 2.0 (SD) mV depolarization of the maximum diastolic membrane potential of the primary pacemaker of the sinus node which lasted for 1.8 +/- 0.3 seconds. Following vagal stimulation, there was an increase of 0.2 mM in the activity of potassium in the extracellular space recorded with a potassium-sensitive electrode; this peaked between 1.4 and 2.5 seconds and cleared with an exponential time course. The halftimes for recovery ranged between 2.8 and 4.6 seconds. The initial peak slowing of the bimodal time course and the acceleratory component therefore appear to be direct effects of acetylcholine. The secondary slowing occurs after acetylcholine presumably has been inactivated and occurs coincidently with the accumulation of potassium in the extracellular space.

Acetylcholine↗

PubMed1976

Antigen stimulation of prostaglandin synthesis and control of immune responses.

Within 2 min following the intravenous injection of sheep erythrocytes (sRBC) there occurs 20 to 80-fold increase in prostaglandin (PG) F2alpha in the spleen. This burst of synthesis is followed by a slow decline to control levels over the next 1-4 hr. No increase in splenic PGF2alpha levels is observed between 24 and 72 hr after injection. Injection of colloidal carbon results in a small increase, approximately 20% of the increase in PGF2alpha observed with sRBC. The early increase in splenic PGF2alpha levels stimulated by sRBC is also dependent upon thymus-derived (T) cells, since the increase is small or nonexistent in athymic mice and NZB mice. Also, the elevation of splenic PGF2alpha levels is blocked by the administration of indomethacin or Ro 20-5720, both of which block the synthesis of prostglandin. A small increase (2-fold) in PGF2alpha levels occurs in the thymus. A soluble antigen, bovine gamma globulin, stimulated a bimodal increase in splenic PGF2alpha levels, the early peak occurring at 2 hr and the later increase occurring at 48 hr. Using inhibitors of prostaglandin synthesis, it is possible to enhance the appearance of cells forming 19S antibody against sRBC, both in vivo and in vitro. Furthermore, inhibition of prostaglandin synthesis enhances DNA synthesis induced in a two-way mixed-lymphocyte reaction only in whole spleen cell cultures and not in cultures of spleen cells purified by passage over glass wool. Based on this evidence, it is proposed that the prostaglandins represent a major soluble mediator in the control of T cell-T cell interactions and also play an important part in T-B (bone-marrow derived) cell interactions.

Animals↗

PubMed1977

Modification of human DNA-dependent RNA polymerase activity by cyclic GMP.

The effect of low concentrations of cyclic GMP (guanosine 3':5'-cyclic monophosphate) on the in vitro enzymatic activities of DNA-dependent RNA polymerases isolated from human peripheral blood lymphocytes has been investigated. In agreement with earlier studies which employed isolated nuclei as the enzyme source, an increase in the activity of partially purified RNA polymerase I is observed in the presence of cyclic GMP (10(-8) to 10(-10)M). RNA polymerase II activity is inhibited by the presence of cyclic GMP at concentrations between 10(-4) and 10(-10)M. RNA polymerase III activity is stimulated in a bimodal fashion by the presence of cyclic GMP with maximal activity noted at 10(-8) to 10(-10) M and 10(-5)M. In addition, [3H]cyclic GMP binds specifically to chromatographic fractions which are known to contain RNA polymerases I, II and III. This binding to RNA polymerases II and III is apprarently less tenacious as demonstrated by dissociation studies. The observations provide additional evidence for a role for cyclic GMP in the regulation of RNA synthesis.

Cyclic AMP↗

PubMed1975

Response patterns to noxious and non-noxious stimuli in rostral trigeminal relay nuclei.

Postimulus time histogram analysis of second-order neuron responses in rostral trigeminal relay nuclei of cat demonstrated characteristic firing patterns after noxious (tooth pulp) and non-noxious (tooth tap) stimuli. The response to noxious stimulation was prolonged and frequently bimodal while the response to non-noxious stimulation was brief. The same neurons were fired by electrical stimuli applied directly to nucleus caudalis but with longer latencies suggesting a contributory role of nucleus caudalis to the characteristic prolonged bimodal response pattern to noxious stimuli. Interacting noxious and non-noxious stimuli using condition-test sequences demonstrated further stimulus mode-related changes in firing patterns. Electrical conditioning stimuli in nucleus caudalis reduced some responses while strychnine sulfate applied into nucleus caudalis augmented the responses evoked in rostral nuclei by both noxious and non-noxious peripheral stimuli. Nucleus caudalis appeared to contain elements which may modulate activity in rostral trigeminal nuclei by either augmenting or reducing specific firing patterns of second-order neurons in rostral relay nuclei.

Animals↗

PubMed1992

[Transesophageal atrial stimulation in 168 patients].

Transesophageal atrial stimulation was performed in 168 patients, 95 males and 73 males, 20 to 81 years of age. The indication for atrial stimulation was the study of some bradyarrhythmia in 109 and ischemic heart disease in 59. An esophageal catheter was introduced through the nose and placed at a spot where a bimodal P wave was obtained. Stimulation was performed using a baby Medtronic stimulator coupled to a Vygon amplifier delivering an output of 30 volt. Sinus node recovery time was measured after 2 to 3 min of stimulation at different rates. Wenckebach and 2:1 A-V block as well as ST deviation were determined. Sick sinus syndrome was diagnosed in 41 cases through altered sinus node recovery time and/or secondary pauses; 35 patients showed Wenckebach rhythm at a stimulation rate over 120 per min; 2: 1 A-V block appeared in 22. Ischemic ST-T changes were produced in 20 subjects. No complications were observed, confirming this approach as a simple and effective way to achieve atrial stimulation for diagnostic purposes.

Adult↗

PubMed1992

The bradykinin receptor of the rat uterus affects the ligand properties of charged mercurials.

Using monovalent organic mercurials to modify the response to the oxytocic action of bradykinin (BK) on the rat uterus, a charge effect, related to the reagent applied, was noted. With neutral, and positively charged mercurials, a bimodal pattern of activity, causing stimulation of BK contraction at lower, and inhibition at higher concentrations was observed. With negatively charged mercurials transient stimulation occurred, inhibition only appearing after very large doses and long periods of incubation. Anionic charges of the bradykinin receptor affect the ligand properties of mercurials, repelling negative charges. By themselves, mercurials did not cause any response.

Acetylcholine↗

PubMed1978

External nucleus of inferior colliculus: auditory and spinal somatosensory afferents and their interactions.

1. The discharges of 129 units were studied in the external nucleus of the inferior colliculus of 11 anesthetised and paralyzed cats. This region is known to receive fibers from auditory nuclei and the dorsal column nuclei. 2. Stimuli used were pure tone bursts, monaural or binaural, tactile stimulation of the body surface, and electrical stimulation of the dorsal columns (DC) at a low cervical level and of the contralateral and ipsilateral tibial nerves. 3. Forty-six percent of units were only influenced by one type of stimulation (26% auditory, 20% DC). Of the remaining bimodally influenced units, the majority was excited by pure tone stimuli and inhibited by DC stimulation. 4. A small proportion of the total population (18%) was excited by both DC and auditory input, and units sensitive to both tones and tactile stimulation of the skin were rare (4%). 5. Auditory tuning curves were generally very broad compared with those of units in the central nucleus of the inferior colliculus. Similarly, somatic receptive fields were large and usually extended over a whole limb. 6. The majority of tone-responsive units were influenced binaurally (70%); most somatic receptive fields were located on the contralateral fore- or hindlimb (16/18). 7. The results indicate that both auditory and somatosensory information is contained in the discharges of units in the external nucleus of the inferior colliculus. 8. Speculations are made about the role of this nucleus in descending auditory input to the spinal cord and in the comparison of auditory and cutaneous information during sound-evoked coordinated body movements.

Acoustic Stimulation↗

PubMed1976

Activities of antennal and ocellar interneurones in the protocerebrum of the honey-bee.

1. Unit responses to olfactory and mechanical stimuli of the antennae, and illumination of the ocelli, were recorded extracellularly in the protocerebrum of the honey-bee. 2. Bimodal units responded both to antennal and to ocellar stimuli; antennal units responded to the former and the ocellar units to the latter. Some antennal units responded to olfactory stimuli (olfactory units), and others responded to mechanical stimuli (mechanical units). 3. Ocellar units in the brain showed phasic responses at the start and/or cessation of illumination. Six types of responses were found. 4. About two-thirds of the bimodal units showed the same type of response to stimulation of the antennae as to stimulation of the ocelli. Most of them showed excitation by each stimulus. 5. Bimodal units were distributed around the alpha-lobe in the protocerebral lobe, whereas the antennal and the ocellar units were widely distributed. 6. By turning off the ocellar illumination, background discharge frequency, and the pattern and magnitude of responses to antennal stimuli, were changed. The activities of the ocellar units were altered by inputs from the antenna. 7. It was postulated that antennal and ocellar inputs converge and interact with each other in the protocerebral lobe of the honey-bee.

Action Potentials↗

PubMed1978

[Responses of the neurons of the magnocellular portion of the medial geniculate body to acoustic and somatosensory stimulation].

The responses of 150 neurons of the magnocellular division of the medial geniculate body (MGB) to sound click and to contralateral forepaw electrical stimulation were studied in cats immobilized with myorelaxine. 68% of the studied neurons had bimodal responses, 16.6% of neurons responded only to click, and 15.4% - only to forepaw stimulation. The responses to click began with excitation more frequently, while initial inhibition was more often evoked by the forepaw stimulation. Latencies of the spike responses to click were between 5-27 ms (at an average 11.6 ms) and to forepaw stimulation between 6-33 ms (at an average 16.2 ms). A positive correlation was found in the same neurons between spike latencies to click and to forepaw stimulation as well as between the spike latencies to stimulation of the forepaw and of the spinal cord dorsal funiculus. A conclusion is made that the magnocellular division of the MGB is the transitional structure between VP and parvocellular division of the MGB and that is connected mainly with the auditory system. It is suggested that somatosensory input to the magnocellular division of the MGB is formed predominantly by the medial lemniscal fibres.

Animals↗

PubMedDate not supplied

In vitro analysis of alpha-adrenoceptor interactions with the myogenic response in resistance vessels.

The interaction of alpha 1- and alpha 2-adrenoceptor constriction of isolated rat cremaster small arteries (mean diameter +/- SEM, 114 +/- 5 microns) with the myogenic mechanism was examined with in vitro videomicroscopy. Microdissected vessels were double-cannulated with glass micropipets in a tissue bath, and intraluminal pressure was set at 65 mm Hg baseline pressure. Norepinephrine (NE) concentration-response curves were obtained alone and in the presence of prazosin or rauwolscine to establish the concentration of NE required to selectively stimulate alpha 1- or alpha 2-adrenoceptors. A bimodal response was produced by NE alone, indicating interaction with more than one receptor population. Rauwolscine and prazosin each produced dextral displacement at low (< 0.1 microM) NE concentrations. However, while prazosin exhibited competitive antagonism, rauwolscine did not antagonize NE at concentrations > or = EC50 value. Thus, both alpha 1- and alpha 2-adrenoceptors mediate constriction at low NE concentrations, but only alpha 1-receptors contributed to constriction at intermediate and high concentrations. These data are in contrast to previous findings for the same vessels studied in vivo. Diameter responses to increases and decreases in transmural pressure from baseline were examined in the relaxed (passive) state with nitroprusside present, during spontaneous intrinsic tone, and during induced alpha 1- or alpha 2-tone (EC20 concentration of NE plus rauwolscine or prazosin). Myogenic constriction during increases in lumen pressure and myogenic inhibition of tone during decreases in pressure were greatest during alpha 2-tone, less during intrinsic tone and least during alpha 1-tone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Effects of adenosine on histamine release from human lung fragments.

The actions of adenosine on histamine release of human lung fragments were investigated. Histamine release was stimulated either with the calcium ionophore A23187 or with concanavalin A. Adenosine and its analogue 5'-N-ethylcarboxamidoadenosine alone had no significant effect on basal release or on the release elicited by A 23187 or concanavalin A. However, in the presence of the adenosine receptor antagonist 8-[4-[[[[(2-aminoethyl)amino]-carbonyl]methyloxy]-phenyl]-1, 3-dipropylxanthine (XAC), which itself did not affect the release, adenosine increased the stimulated histamine release. On the other hand, in the presence of the nucleoside transport inhibitor S-(p-nitrobenzyl)-6-thioinosine (NBTI), adenosine caused a reduction in stimulated histamine release. NBTI itself caused a stimulation of release. Thus, a stimulatory effect of adenosine was seen in the presence of XAC, whereas an inhibitory effect was unmasked by NBTI. From these data it is concluded that adenosine exerts two opposing effects on histamine release in the human lung which neutralize each other: it inhibits release via a site antagonized by XAC, which presumably represents an A2 adenosine receptor, and it stimulates release via a mechanism that is blocked by NBTI, suggesting that adenosine needs to reach the interior of cells to exert this effect. The slight stimulatory effect of NBTI alone demonstrates that trapping intracellularly formed adenosine inside mast cells leads to sufficient concentrations of adenosine to stimulate histamine release. These findings suggest an important bimodal role of adenosine in regulating histamine release in the human lung.

Adenosine↗

PubMed1992

Excitatory/inhibitory interaction in the LSO revealed by point process modeling.

We studied lateral superior olivary (LSO) unit responses to binaural tone-bursts using a general point process approach. We show that inhibition of the ipsilaterally elicited response by contralateral stimulation cannot be modeled simply as a reduction of the ipsilateral input. Statistical analyses reveal that inhibition operates by scaling the intensity of the point process describing the ipsilateral response. In some cases the scaling process has secondary effects: Binaurally elicited discharges produce bimodal interspike interval histograms from units that produce unimodal interval histograms under monaural stimulation. We present a specific point process model that describes the scaling process and successfully replicates the observed responses to monaural and binaural stimulation of the three types of LSO units: slow choppers, fast choppers, and bimodal units. We interpret scaling as a shunting inhibitory process in these LSO neurons. By relating scaling magnitude to interaural level difference, we demonstrate the spatial sensitivity of LSO units.

Acoustic Stimulation↗

PubMed1992

Stimulation by TGF beta of chick embryo fibroblasts--inhibition by an IGFBP-3.

The multiple effects of TGF beta on cell proliferation are not well understood. Our results show that TGF beta was a good but transient mitogen for chick embryo fibroblasts. DNA synthesis was three- to fourfold increased, even at high concentrations of TGF beta. We did not show a bimodal effect. An inhibitor of cell growth, that inhibits 100% of stimulation induced by serum in CEF, was purified to homogeneity from medium conditioned by mouse 3T3 cells. This inhibitor has been shown to be an IGF-binding protein (mIGFBP-3). In the present work, this mIGFBP-3 inhibited the TGF beta stimulation by about 50%, while the stimulation induced by PDGF or insulin was not inhibited by mIGFBP-3. Furthermore, TGF beta stimulation, in the presence of a high concentration of insulin in conditions which would saturate IGF receptors, was not significantly inhibited by mIGFBP-3. All together these results suggest that a part of the mitogenic effect of TGF beta may be through increasing IGF secretion and eventually other growth factors such as PDGF (as suggested previously).

3T3 Cells↗