Optimal Stimulation Frequency Research Articles

Optimal frequency of carotid sinus nerve stimulation in treatment of angina pectoris.

Carotid sinus nerve stimulation (CSNS) was applied in seven angina pectoris patients for periods of 1–2 min, using a modified Angistat (Medtronic) stimulator at frequencies ranging from 20 to 200 Hz. Stimulation at frequencies between 80 and 120 Hz elicited the largest increase in R-R interval and blood pressure reduction. Due to technical limitations of the device, the Angistat stimulator appears to be unsuitable if stimulation frequencies in excess of 120 Hz are to be applied. We conclude that the optimal frequency of the Angistat CSNS stimulator in the treatment of angina pectoris is between 80 and 120 Hz.

Influence of chronic treatment with neomycin and kanamycin on N 1 suppression produced by contralateral olivo-cochlear bundle stimulation in cats.

Twenty cats received one subcutaneous injection per day of neomycin sulfate (100 mg/kg/day) and 5, kanamycin sulfate (200 mg/kg/day) for 8 days; experiments were performed on the ninth day. Nine of 10 untreated control, 13 of 20 neomycin and 5 of 5 kanamycin animals had normal cochlear responses to acoustic stimulation and were usable for this study. The efficacy of contralateral olivo-cochlear bundle (COCB) stimulation was determined at 400 (optimally effective) and 100 (minimally effective) Hz for 4 different current strengths at each frequency of stimulation. Six of the neomycin animals exhibited a significant block of COCB stimulation effects at all currents and both frequencies of stimulation, while the other 7 neomycin animals and the kanamycin animals showed a significant increase in the effectiveness of COCB stimulation at the lower currents of the higher (optimal) stimulation frequency. Thus, chronic treatment with neomycin and kanamycin produces changes in COCB stimulation effects, indicating th...

Tonic vibration reflex in human and monkey subjects.

1. Both in human subjects and monkeys, the tonic vibration reflex, TVR, was observed during vibratory stimulation of the muscle. In the latter, TVR reaches its maximum soon after vibratory application.2. In the monkey, unitary EMG was recorded during vibratory stimulation and nonsequential interspike interval histograms were obtained. Intervals of unitary EMG were shown to occur on the principle of integer multiplication of the vibratory cyclic time.3. A gradual increase or decrease of TVR during vibratory stimulation in the human subject or the monkey is effected by the EMG discharges of shorter or longer firing intervals which occur on this principle.4. Both in human subjects and monkeys, the TVR becomes larger with the higher range of vibratory frequency. Beyond a certain vibratory frequency the TVR shows a gradual decrease. The relationship between the TVR and the vibratory frequency was called the TVR-f relation. There is an optimal frequency of vibratory stimulation for producing the largest TVR tension.5. The size of the reflex tension from TVR-f relation depends on the discharge frequency of the unitary EMG, which occurs according to the principle of the integer multiplication of original vibratory cyclic time.

EEG synchronization induced by high frequency midbrain reticular stimulation in anesthetized cats

High frequency stimulation of the brain-stem reticular formation produces a generalized desynchronization of the electrocortical waves. Low frequency stimulation of the same structures in the awake animal may induced EEG synchronization, mainly consisting of increased spindle activity. In a study of the EEG effects of midbrain electrical stimulation in anesthetized cats, it was discovered that high frequency stimulation occasionally produced an immediate and wide-spread increase in cortical slow wave activity. This response was present only in animals under relatively light anesthesia. In non-anesthetized cats, either curarized or after post-collicular transection, high frequency midbrain reticular stimulation resulted in desynchronization. Under light chloralose-urethane or Nembutal anesthesia desynchronization by reticular stimulation was frequently replaced by (1) regular slow waves of large amplitude at 1–4 c/sec, (2) a marked increase and regulation of the randomly occurring chloralose waves or (3) an increase in the 6–10 c/sec spindle activity. In still deeper anesthesia the threshold for obtaining synchronization increased and finally the response disappeared. The optimal stimulation frequency for producing synchronization under anesthesia was around 100–300/sec, but clear-cut effects were usually also obtained at frequencies down to about 30/sec and occassionally at rates as low as 10/sec. EEG synchronization under anesthesia was elicited from the entire reticular formation of the midbrain, which was explored in steps of 1 mm with bipolar stimulating electrodes. At caudal levels a low threshold area was found in the mid-line in the region of the decussation of the brachium conjunctivum. The response was, however, independent of this structure, being present also in chronic cats after cerebellectomy. At rostal levels of the midbrain the optimum zone was located ventro-lateral to the central grey substance. When present on midbrain stimulation, EEG synchronization could also be produced by high frequency stimulation of thalamic midline or intralaminar nuclei. Synchronization in response to high frequency reticular stimulation was recorded from the entire neocortex and the slow waves were bilaterally synchronous. Depending on the site of stimulation the greatest amplitude was frequently recorded over the parieto-occipital or anterior frontal regions. The same stimulus sometimes produced synchronization in some leads and desynchronization in others. The response was absent from the hippocampus.

EFFECTS OF TEMPERATURE ON ISOMETRIC CONTRACTION OF RAT MUSCLE.

The effects of temperature on the basic characteristics of isometric contraction were studied in the triceps surae of white albino rats. The influences of tetanic fusion and Wedensky inhibition on tension development were analyzed. The results showed linear increase of maximal isometric tetanic tension and increase in the rate of rise and fall of twitch and tetanic isometric contractions with increase in temperature. Indirect stimulation produced somewhat lower tetanic tensions than direct stimulation. The optimal frequency of stimulation for maximal tetanic tension development was usually lower than the critical frequency of tetanic fusion. Reduction of tension by excessively high frequencies of stimulation, due to the Wedensky effect, was observed with indirect stimulation, and occurred at a lower frequency than the critical frequency of fusion.

Changes in the lability of smooth muscle during stimulation of the sympathetic and parasympathetic nerves

The effect of sympathetic and parasympathetic nerves of a smooth muscle—the retractor penis—was investigated. Stimulation of the sympathetic nerve extends the limits of the optimal and pessimal frequency of stimulation towards greater frequencies, the action current frequency and amplitude increase, while the value of the resting current decreases. On stimulation of the parasympathetic nerve, the action current frequencies become decreased, their amplitude declines and the resting current rises. A suggestion is made that the “antagonism” of the sympathetic and parasympathetic innervation of the smooth muscle apparently is due to the action exerted on the functional properties of the muscle, particularly on its lability.

Hypothermia and cortical evoked potentials.

The behavior of the recruiting response during hypothermia was investigated, and the following results were obtained. 1. Recruiting response was recorded from the frontal area by stimulation of the nucleus ventralis anterior or the anterior pole of the reticular nucleus in rat. The brain temperature was lowered gradually till 18°C. and then raised slowly to normal temperature. All the changes to be stated below were reversible. 2. Spontaneous background EEG was decreased in amplitude, and slowed in rate as the brain temperature was lowered, and flattened at 18°C. Dominant spindle bursts of high amplitude and low frequency appeared between 29°C.-25°C. 3. The optimal frequency of stimulation was determined for each temperature. There was linear relationship between the logarithm of the optimal frequency and the brain temperature in a range from 36°C. to 18°C. 4. A value of temperature characteristic (μ) 7500 cal. was obtained from the law of Arrhenius applied to the data. 5. Large and small responses appeared alternately when the frequency of stimulation was somewhat higher than the optimal one, and only small ones appeared when the frequency was much higher. The mechanism of alternation was discussed. I wish to thank Prof. K. Motokawa for his invaluable discussion and suggestion throughout the course of the experiment and the preparation of the manuscript.