Effects Of Acoustic Stimulation Research Articles

Enhanced effective diffusion in sub-wavelength, axon-scale microchannels using surface acoustic waves

Excitation using surface acoustic waves (SAW) has demonstrated efficacy in improving microscale particle/chemical transport due to its ability to generate microscale wavelengths. However, the effects of acoustic stimulation on transport processes along the length of sub-wavelength microchannels and their underlying mechanisms, essential for long-range transport, have not been examined in detail. In this work, we investigate diffusion along the length of subwavelength microchannels using experimental and simulation approaches, demonstrating enhanced transport under SAW excitation. The microchannel-based enhanced diffusion mechanisms are further studied by investigating the acoustic pressure and streaming fields, finding that the degree of enhancement is a function of applied power, microchannel dimensions, and viscosity. This microchannel-based diffusion enhancement approach is applicable to microfluidic and biomedical microscale transport enhancement, with the findings here being relevant to acoustic-based micro-mixing and neurodegenerative therapies.

Effects of Acoustic Stimulation on Fluid Flow in Porous Media

Acoustic waves are mechanical waves that can be generated via vibrations. The use of such waves for enhancing flow and transport in porous media has some advantages over traditional enhanced recovery methods including eliminating bypassing effects and environmental hazards. Many physical mechanisms have been identified to improve recovery by applying an acoustic wave. However, the relative contributions of different mechanisms to the stimulated flow and transport phenomena are not still well understood. There are also uncertainties regarding the effects of important controlling factors such as frequency or the efficiency of different source coupling methods. In this work, a multiphysics model is developed to address the latter issues and propose a criterion to distinguish different regimes of acoustically induced effects. Simulation results of this model are correlated to the recovery enhancements to provide the required applied stress or supplied energy that causes observable changes in fluid flow behavior under laboratory conditions. A loss number of Nl is proposed based on the dimensionless analysis of wave equation in fluids where the most energy dissipation occurs. The critical values of Nl are obtained by implementing a classifier machine learning algorithm on a data set from the literature. When Nl is less than 2.1 × 10–7, the recovery enhancement is expected to be caused by mechanical effects, and therefore lower frequency (seismic) waves are favorable. At an Nl greater than 10–6, however, higher frequency (ultrasonic) waves are preferred since the changes in flow behavior are triggered by the adsorbed acoustic energy. In seismic excitations, coupling the source to the pore fluid gives the highest performance, while in ultrasonic treatments, the maximum viscosity reduction can be achieved when a transient frequency scenario is adopted. The results of this study give a better understanding of mechanisms behind the effect of acoustic wave application in porous media.

Effect of acoustic stimulation after sleep spindle activity

Effect of acoustic stimulation after sleep spindle activity

Acoustic stimulation effect on temporal processing skills in elderly subjects before and after hearing aid fitting

AbstractAging can alter, temporal processing and affect speech perception.Aim: To compare temporal processing auditory processing in elderly subject to and new hearing aid users.Materials and Methods: The study included 60 elderly patients with bilateral sensorineural hearing loss. The procedures selected were the Duration Pattern Tests (DPT) and gaps in noise (GIN) test were used to analyze the responses of correct identification, and the temporal acuity threshold before and after the fitting of hearing aids. Study design: clinical and experimental research with non-probability sample of convenience.Results: There was no statistically significant difference between the responses from GI and GII individuals. The elderly users of hearing aids had a lower gap detection threshold, greater recognition of gaps and of discrimination of the duration pattern in relation to when they were only potential users.Conclusion: There was a deterioration in temporal processing skills, regardless of hearing loss degrees. Thus, the effect of acoustic stimulation by the use of a hearing aid improved resolution and temporal ordering.

Effect of acoustic stimulation on GABAergic neurons in limbic structures of Krushinskii-Molodkina rats

Quantitative study of GABAergic and main cells in the hippocampus and piriform cortex of Krushinskii-Molodkina rats was performed 1 month after the incidence of seizure activity evoked by acoustic stimulation. The number of neurons significantly decreased in both regions and, particularly, in the hippocampus and central area of the piriform cortex.

Effect of acoustic stimulation on cell composition of auditory brain structures in Krushinskii-Molodkina rats

We studied the effect of acoustic stimulation on cell composition of auditory brain structures in Krushinskii-Molodkina rats. Significant structural changes in the inferior colliculi of rats with high seizure activity were revealed 1 month after acoustic stimulation. Therefore, this brain structure plays a role in the development of audiogenic epileptic activity.

Effects of acoustic stimulation on cardiovascular regulation during sleep.

The interaction of wake-sleep states and acoustic stimulation on cardiovascular regulation was studied on rats implanted with electroencephalogram and electromyogram electrodes and an arterial catheter. Mild acoustic stimuli (1000 Hz, 90 dB, 50-ms beeps) were administered during Wakefulness (W), non-rapid eye movement (NREM) sleep and REM sleep and the changes induced in heart period (HP, ms) and mean arterial pressure (MAP, mmHg) were analyzed. Two 30-s sequences of beat-to-beat HP and MAP values were considered before (I) and after (II) acoustic stimulation, respectively. By the effect of stimulation, state-dependent stimulus-locked HP and MAP oscillations were observed, HP oscillations being grossly parallel to the MAP ones but delayed with respect to MAP in the ascending part only; HP and MAP spontaneous fluctuations (HP and MAP variability) increased in NREM and REM sleep (but not in W); HP vs MAP correlation coefficient increased in an algebraic sense. These results show that 1) acoustic stimulation primarily affects the peripheral resistance, and secondarily, through the baroreceptor reflex, HP, thereby increasing the impact of peripheral versus centrally driven autonomic influences on the heart; 2) in NREM sleep, heart excitability is higher than requested by the baroreflex function; 3) cardiac variability is increased by acoustic stimulation during sleep (but not in W); this, in addition to the effects of point 2, may favor cardiac arrhythmias in NREM sleep. Thus, mild acoustic stimuli not perturbing cardiovascular regulation during W may create a specific risk factor during sleep in pathophysiologic conditions.

Noise stimulation decreases the concentration of norepinephrine in the rat cochlea

The present study was designed to analyze, by using high performance liquid chromatography (HPLC), the effect of acoustic stimulation on the cochlear concentration of norepinephrine (NE). Independently of the rat strain (Long-Evans or Wistar strains), NE concentration decreased about 18% when animals were exposed to white noise (90 dB SPL for 1 h). The same decrease was observed in animals perfused by aortic pathway to remove the blood, indicating that this decrease corresponds exclusively to a neurophysiological process. In fact, these findings could indicate that noise stimulation is involved in the NE release from sympathetic fibers innervating the cochlea. This likely release of NE supports that sympathetic fibers play a functional role in cochleae exposed to noisy situations.

Effects of Acoustic Stimulation on Rat Behavior after Withdrawal of Methamphetamine

Effects of Acoustic Stimulation on Rat Behavior after Withdrawal of Methamphetamine

The postnatal development of stimulated deoxyglucose uptake into the mouse cochlea and the inferior colliculus

The effect of acoustic stimulation on the postnatal development of deoxyglucose uptake into the mouse cochlea and the inferior colliculus was evaluated. Animals between postnatal day 4 and 20 were separated into four different groups depending on their age. Tritiated deoxyglucose was injected intraperitoneally into each animal and tracer uptake was quantitated by microdissection of the tissues and scintillation counting. Acoustic stimulation at a noise level of 100 dB (A) resulted in supra-normal levels of deoxyglucose uptake for all auditory tissues during postnatal days 13, 14, and 15. The lateral wall tissues, which are non-sensory and non-neuronal, also increased deoxyglucose uptake following acoustic stimulation in a manner that paralleled the uptake by the sensory structures. Serum radioactivity and glucose levels remained unchanged during postnatal development, with these parameters remaining stable with acoustic stimulation.

Acoustic stimulation alters deoxyglucose uptake in the mouse cochlea and inferior colliculus.

Deoxyglucose uptake and activities of hexokinase and glucose-6-phosphatase in auditory structures (organ of Corti, stria vascularis and spiral ligament, modiolar section of VIIIth nerve, inferior colliculus) and non-auditory tissues (heart, kidney, liver) of the mouse were analyzed. [3H]Deoxyglucose was given as a pulse into the tail vein and uptake was quantitated by microdissection of tissues and scintillation counting. Radioactivity in cochlear tissues was maximal after 45-60 min and declined with a half-life of 30-60 min. Deoxyglucose 6-phosphate represented ca. 60% of total radioactivity (heart, inferior colliculus, greater than 80%). The ratio of hexokinase to glucose-6-phosphatase activity was considerably lower in the auditory periphery than in brain. The rank order was inferior colliculus much greater than VIIIth nerve approximately equal to heart greater than stria vascularis and spiral ligament greater than kidney greater than organ of Corti approximately equal to liver. Exposure to broadband noise increased glucose utilization in all auditory structures. Uptake was maximally (2- to 3-fold) stimulated at moderate noise intensity (55-85 dBA). In addition, the auditory system showed two salient features: at high intensities (100 and 115 dBA) deoxyglucose uptake decreased from the maximum; and the non-sensory tissues of the cochlea (stria vascularis and spiral ligament) responded to sound parallel to the sensory structures at all levels of stimulus intensity. There were no effects of acoustic stimulation on serum glucose levels, serum kinetics of deoxyglucose, or deoxyglucose uptake into other body tissues.

The effects of acoustic stimulation on glucose utilization in the inner ear

Glucose uptake into tissue can be mapped by the incorporation of 14C‐2‐deoxyglucose (2‐DG). However, this technique as employed in previous investigations does not lend itself to use in the cochlea. We have developed an alternative technique which permits the visualization of 2‐DG uptake in the tissues of the inner ear. 2‐DG (16 μCi/100 g in 0.1 ml) was injected intracardially into gerbils. Animals were exposed to wide band noise at intensities of 25, 45, 65, 85. or 105 dB SPL for one hour in a double‐walled sound attenuated chamber. Control subjects received no exposure. Gerbils were then sacrificed by decapitation, and the cochleas dissected whole and frozen in Freon 12 cooled to −160°C. Inner ears were then freeze‐dried. embedded in Epon or Spurr resin utilizing only organic solvents. and cut in mid‐modiolar section. Half cochleas were exposed on LKB Ultrofilm for 10 days. Control inner ears showed maximal uptake of 2‐DG in stria vascularis. Our initial data indicate that incorporation of 2‐DG increased in the spiral ganglion and VIIIth nerve during exposure to noise, especially at 85 and 105 dB SPL. [Work supported by NIH/NINCDS grants NS00176 and NS14945.]

Some experiments on temporary threshold shifts produced by short tones.

TTSs produced by short (500-1000 msec) pure frequency (2000, 3000, 4000 c.p.s.) tones on normal young subjects show, under comparable conditions, the same essential characteristics as TTSs which follow longer stimulations. In particular, they show a tendency to a displacement of their maximal values, as soon as the stimulating tone is presented at adequately high (100 dB SPL) intensity levels, towards a frequency about a halfoctave higher than that of the stimulating tone. In our experiments, however, this tendency was more clearly and constantly demonstrable following stimulations with 3000 c.p.s. tones. Significant individual variations in quantitative aspects of the TTSs have been observed. It is suggested that the use of short tones may be easier and more applicable in practice in investigations concerning the after effects of acoustical stimulation and possible also in procedures aimed at obtaining a better understanding of the significance of individual variations in the behaviour of the receptor organ upon exposure to high intensity stimulations.

Some Experiments On Temporary Threshold Shifts Produced By Short Tones

TTSs produced by short (500-1000 msec) pure frequency (2000, 3000, 4000 c.p.s.) tones on normal young subjects show, under comparable conditions, the same essential characteristics as TTSs which follow longer stimulations. In particular, they show a tendency to a displacement of their maximal values, as soon as the stimulating tone is presented at adequately high (100 dB SPL) intensity levels, towards a frequency about a half-octave higher than that of the stimulating tone. In our experiments, however, this tendency was more clearly and constantly demonstrable following stimulations with 3 000 c.p.s. tones. Significant individual variations in quantitative aspects of the TTSs have been observed. It is suggested that the use of short tones may be easier and more applicable in practice in investigations concerning the after effects of acoustical stimulation and possibly also in procedures aimed at obtaining a better understanding of the significance of individual variations in the behaviour of the receptor organ upon exposure to high intensity stimulations.

Effects of acoustical stimulation on equilibrium

Effects of acoustical stimulation on human equilibrium were measured on a rail test developed by Graybiel and Fregly [Acta Otolaryngol. 61, 292–312 (1966)]. Two tasks were used—standing with eyes open on rails 114in. and 34in. wide and standing with eyes closed on rails 134in. and 114in. wide. Five noise conditions were used—bilateral and unilateral presentations of impact (135 dB) and continuous (110 dB), and a bilateral control (75 dB). Analyses revealed no significant effects of types of noise on rail performance. These findings appear somewhat at variance with earlier results [H. C. Sommer and C.S. Harris, Aerospace Med. Res. Lab. Rep. 70-26, Wright-Patterson AFB, Ohio (1970); C.W. Nixon, C.S. Harris, and H. E. von Gierke, Aerospace Med. Res. Lab. Rep. TR-66-85, Wright-Patterson AFB, Ohio (1966)] indicating that asymmetrical, free-field noise stimulation produced significant impairment on a similar test, but their asymmetrical conditions involved unequal protection of the ears, resulting in a much greater interaural intensity difference.

Effects of acoustical stimulation and deprivation on song development in red-winged blackbirds ( Agelaius phoeniceus)

Isolated male red-winged blackbirds develop abnormal songs. Some normal components are delivered with abnormal order and timing. Two males deafened at about 10 days of age develop highly abnormal songs, although they retain more structure than other early-deafened songbirds. In masking noise from 8 to 330 days, one individual sings like a deaf bird. With reduced periods of masking singing is more like that of intact birds. Playback of normal song results in imitation. Individual isolates are unselective in learning both conspecific and Baltimore oriole song. Grouped males are more selective. New songs are added in the second year. Improvisation is important in redwing song development under these conditions but its role in the wild remains uncertain.

Convergence of acoustic and photic stimuli on visual cortical neurons in the unanesthetized rabbit

1. A click, if applied at different intervals before or after a flash, produces phasic and tonic changes in the unit responses. 2. Phasic changes which the clicks produce in the photic response of the neuron and the dependence of these changes on the excitatory and inhibitory phases of the photic response are evidence of a specific action of acoustic stimulation on activity of the particular neuron. Tonic changes in the unit response indicate the existence of nonspecific effects of acoustic stimulation on visual cortical neurons.

Effect of acoustic stimulation on the pituitary-adrenal system in healthy rats and rats genetically highly sensitive to sound

Effect of acoustic stimulation on the pituitary-adrenal system in healthy rats and rats genetically highly sensitive to sound

The effects of acoustic stimulation on cessation and initiation of non-nutritive sucking in neonates

Discrete changes in the human newborn's sucking behavior in response to acoustic stimulation was studied. In order to obtain a sensitive comparison measure for stimulus conditions, control trials were randomly interspersed with stimulus trials. To prevent temporal biasing effects, variable interstimulus intervals were used, and stimuli were presented contingent on the infant's sucking state on each trial. Results from 30 Ss clearly demonstrate the presence of two dichotomous responses: (1) response initiation to the stimulus in the presence of non-sucking; and (2) response cessation to the stimulus in the presence of active-sucking. No differences were found among three groups exposed to qualitatively different stimuli of the same intensity, and there was no evidence of habituation of either response.

Effects of acoustic stimulation on the spinal cord

Effects of acoustic stimulation on the spinal cord