Temporal Properties of Chronic Cochlear Electrical Stimulation Determine Temporal Resolution of Neurons in Cat Inferior Colliculus

1999 ◽  
Vol 82 (6) ◽  
pp. 2883-2902 ◽  
Author(s):  
Maike Vollmer ◽  
Russell L. Snyder ◽  
Patricia A. Leake ◽  
Ralph E. Beitel ◽  
Charlotte M. Moore ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Inferior Colliculus ◽  
Cochlear Implants ◽  
Temporal Resolution ◽  
Temporal Processing ◽  
Low Frequency ◽  
Constant Current ◽  
High Frequency Stimulation ◽  
Response Latencies ◽  
Chronic Electrical Stimulation

As cochlear implants have become increasingly successful in the rehabilitation of adults with profound hearing impairment, the number of pediatric implant subjects has increased. We have developed an animal model of congenital deafness and investigated the effect of electrical stimulus frequency on the temporal resolution of central neurons in the developing auditory system of deaf cats. Maximum following frequencies (Fmax) and response latencies of isolated single neurons to intracochlear electrical pulse trains (charge balanced, constant current biphasic pulses) were recorded in the contralateral inferior colliculus (IC) of two groups of neonatally deafened, barbiturate-anesthetized cats: animals chronically stimulated with low-frequency signals (≤80 Hz) and animals receiving chronic high-frequency stimulation (≥300 pps). The results were compared with data from unstimulated, acutely deafened and implanted adult cats with previously normal hearing (controls). Characteristic differences were seen between the temporal response properties of neurons in the external nucleus (ICX; ∼16% of the recordings) and neurons in the central nucleus (ICC; ∼81% of all recordings) of the IC: 1) in all three experimental groups, neurons in the ICX had significantly lower Fmax and longer response latencies than those in the ICC. 2) Chronic electrical stimulation in neonatally deafened cats altered the temporal resolution of neurons exclusively in the ICC but not in the ICX. The magnitude of this effect was dependent on the frequency of the chronic stimulation. Specifically, low-frequency signals (30 pps, 80 pps) maintained the temporal resolution of ICC neurons, whereas higher-frequency stimuli significantly improved temporal resolution of ICC neurons (i.e., higher Fmax and shorter response latencies) compared with neurons in control cats. Furthermore, Fmax and latencies to electrical stimuli were not correlated with the tonotopic gradient of the ICC, and changes in temporal resolution following chronic electrical stimulation occurred uniformly throughout the entire ICC. In all three experimental groups, increasing Fmax was correlated with shorter response latencies. The results indicate that the temporal features of the chronically applied electrical signals critically influence temporal processing of neurons in the cochleotopically organized ICC. We suggest that such plastic changes in temporal processing of central auditory neurons may contribute to the intersubject variability and gradual improvements in speech recognition performance observed in clinical studies of deaf children using cochlear implants.

Temporal resolution of neurons in cat inferior colliculus to intracochlear electrical stimulation: effects of neonatal deafening and chronic stimulation

1995 ◽  
Vol 73 (2) ◽  
pp. 449-467 ◽  
Author(s):  
R. Snyder ◽  
P. Leake ◽  
S. Rebscher ◽  
R. Beitel
Keyword(s):  
Electrical Stimulation ◽  
Inferior Colliculus ◽  
Temporal Resolution ◽  
Transfer Functions ◽  
Discharge Rate ◽  
Pulse Frequency ◽  
Acoustic Stimulation ◽  
Acute Experiment ◽  
Sustained Response ◽  
Central Nucleus

1. Cochlear implants have been available for > 20 yr to profoundly deaf adults who have lost their hearing after acquiring language. The success of these cochlear prostheses has encouraged the application of implants in prelingually deaf children as young as 2 yr old. To further characterize the consequences of chronic intracochlear electrical stimulation (ICES) on the developing auditory system, the temporal-response properties of single neurons in the inferior colliculus (IC) were recorded in deafened anesthetized cats. 2. The neurons were excited by unilateral ICES with the use of a scala tympani stimulating electrode implanted in the left cochlea. The electrodes were modeled after those used in cochlear implant patients. Responses of 443 units were recorded extracellularly in the contralateral (right) IC with the use of tungsten microelectrodes. Recordings were made in three groups of adult animals: neonatally deafened/chronically stimulated animals (192 units), neonatally deafened/unstimulated animals (80 units), and adult-deafened/prior normal-hearing animals (171 units). The neonatally deafened cats were deafened by multiple intramuscular injections of neomycin sulfate and never developed demonstrable hearing. Most of the deafened, chronically stimulated animals were implanted at 6 wk of age and stimulated at suprathreshold levels for 4 h/day for 3-6 mo. The unstimulated animals were implanted as adults at least 2 wk before the acute physiological experiment and were left unstimulated until the acute experiment was conducted. Prior-normal adults were deafened and implanted at least 2 wk before the acute experiment. 3. IC units were isolated with the use of a search stimulus consisting of three cycles of a 100-Hz sinusoid. Most units responded to sinusoidal stimulation with either an onset response or a sustained response. Onset units were the predominant unit found in the external nucleus, whereas sustained units were found almost exclusively in the central nucleus. The temporal resolution of sustained response units was measured with the use of pulse trains of increasing frequency and calculating the discharges/pulse. 4. The range of electrical pulse frequencies to which IC units responded in a temporally synchronized manner was comparable with that produced by acoustic stimulation. The discharge rate/pulse-versus-pulse frequency transfer functions of IC units were uniformly low-pass, although they varied widely in their cutoff frequencies. This variation in pulse response was partially correlated with the unit's response to sinusoids. Most onset neurons responded only to pulse frequencies below 20 pulses per second (pps). Most sustained units responded best to pulse frequencies < 100 pps, and most ceased to respond to pulse frequencies > 300 pps.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of chronic electrical stimulation on GLUT-4 protein content in fast-twitch muscle

1993 ◽  
Vol 264 (4) ◽  
pp. R816-R819 ◽  
Author(s):  
G. J. Etgen ◽  
R. P. Farrar ◽  
J. L. Ivy
Keyword(s):  
Electrical Stimulation ◽  
Protein Content ◽  
Glucose Transporter ◽  
Citrate Synthase ◽  
Low Frequency ◽  
Neuromuscular Activity ◽  
Glut 4 ◽  
Fast Twitch Muscle ◽  
Chronic Electrical Stimulation ◽  
Fast Twitch

Insulin- and contraction-stimulated skeletal muscle glucose transport is governed largely by the GLUT-4 isoform of the glucose transporter. Recently, it has been demonstrated that denervated muscle has decreased GLUT-4 protein content, suggesting that regulation of GLUT-4 protein is related to neuromuscular activity. However, until now the effects of the opposite situation, enhanced neuromuscular activity, could only be speculated on from exercise training studies. In the present investigation the effect of chronic low-frequency electrical stimulation (10 Hz, 8 h/day) on GLUT-4 protein content and citrate synthase activity was determined in the predominantly fast-twitch plantaris. Chronic electrical stimulation enhanced GLUT-4 protein content and citrate synthase activity in the muscles stimulated for 10-20 days. Electrical stimulation lasting 30-40 days resulted in no further enhancement of GLUT-4 protein content while citrate synthase activity continued to increase. Further prolongation of electrical stimulation (60-90 days) resulted in a plateauing of citrate synthase activity. The results suggest that increased neuromuscular activity can act independently of systemic changes to increase total GLUT-4 protein content. They also suggest that both GLUT-4 protein content and citrate synthase activity are positively related to increased neuromuscular activity but that their rates of increase differ substantially.

scholarly journals Factors in fatigue during intermittent electrical stimulation of human skeletal muscle

2002 ◽  
Vol 93 (2) ◽  
pp. 469-478 ◽  
Author(s):  
David W. Russ ◽  
Krista Vandenborne ◽  
Stuart A. Binder-Macleod
Keyword(s):  
Electrical Stimulation ◽  
Low Frequency ◽  
Metabolic Cost ◽  
Peak Force ◽  
Medial Gastrocnemius ◽  
Single Frequency ◽  
High Frequency Stimulation ◽  
Frequency Stimulation ◽  
Low Frequency Fatigue ◽  
Force Time

During an electrically elicited isometric contraction, the metabolic cost of attaining is greater than of maintaining force. Thus fatigue produced during such stimulation may not simply be a function of the force-time integral (FTI), as previously suggested. The goal of the present study was to evaluate fatigue produced in human medial gastrocnemius by intermittent, isometric electrical stimulation with trains of different frequencies (20, 40, or 80 Hz) and durations (300, 600, or 1,200 ms) that produced different peak forces and FTIs. Each subject ( n = 10) participated in a total of six sessions. During each session, subjects received a pre- and postfatigue testing protocol and a different, 150-train fatiguing protocol. Each fatiguing protocol used only a single frequency and duration. The fatigue produced by the different protocols was correlated to the initial peak force of the fatiguing protocols ( r 2= 0.74–0.85) but not to the initial or total FTI. All of the protocols tested produced a proportionately greater impairment of force in response to low- vs. high-frequency stimulation (i.e., low-frequency fatigue). There was no effect of protocol on low-frequency fatigue, suggesting that all the protocols produced comparable levels of impairment in excitation-contraction coupling. These results suggest that, for brief stimulated contractions, peak force is a better predictor of fatigue than FTI, possibly because of the different metabolic demands of attaining and maintaining force.

Effects of electrical stimulation on tinnitus

1984 ◽  
Vol 98 (S9) ◽  
pp. 139-140 ◽  
Author(s):  
John W. House
Keyword(s):  
Electrical Stimulation ◽  
Inner Ear ◽  
Cochlear Implants ◽  
Early Experience ◽  
Chronic Electrical Stimulation

Our early experience with the use of cochlear implants indicated that chronic electrical stimulation to the inner ear tends to help tinnitus. For this reason we have been investigating the use of electrical stimulation as a treatment for the symptom of tinnitus.

Cellular Mechanisms Underlying Antiepileptic Effects of Low- and High-Frequency Electrical Stimulation in Acute Epilepsy in Neocortical Brain Slices In Vitro

2007 ◽  
Vol 97 (3) ◽  
pp. 1887-1902 ◽  
Author(s):  
Yitzhak Schiller ◽  
Yael Bankirer
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Brain Slices ◽  
Low Frequency ◽  
High Frequency Stimulation ◽  
Dependent Manner ◽  
Cellular Mechanisms ◽  
Epileptiform Discharges ◽  
Frequency Stimulation

Approximately 30% of epilepsy patients suffer from drug-resistant epilepsy. Direct electrical stimulation of the epileptogenic zone is a potential new treatment modality for this devastating disease. In this study, we investigated the effect of two electrical stimulation paradigms, sustained low-frequency stimulation and short trains of high-frequency stimulation, on epileptiform discharges in neocortical brain slices treated with either bicuculline or magnesium-free extracellular solution. Sustained low-frequency stimulation (5–30 min of 0.1- to 5-Hz stimulation) prevented both interictal-like discharges and seizure-like events in an intensity-, frequency-, and distance-dependent manner. Short trains of high-frequency stimulation (1–5 s of 25- to 200-Hz stimulation) prematurely terminated seizure-like events in a frequency-, intensity-, and duration-dependent manner. Roughly one half the seizures terminated within the 100-Hz stimulation train ( P < 0.01 compared with control), whereas the remaining seizures were significantly shortened by 53 ± 21% ( P < 0.01). Regarding the cellular mechanisms underlying the antiepileptic effects of electrical stimulation, both low- and high-frequency stimulation markedly depressed excitatory postsynaptic potentials (EPSPs). The EPSP amplitude decreased by 75 ± 3% after 10-min, 1-Hz stimulation and by 86 ± 6% after 1-s, 100-Hz stimulation. Moreover, partial pharmacological blockade of ionotropic glutamate receptors was sufficient to suppress epileptiform discharges and enhance the antiepileptic effects of stimulation. In conclusion, this study showed that both low- and high-frequency electrical stimulation possessed antiepileptic effects in the neocortex in vitro, established the parameters determining the antiepileptic efficacy of both stimulation paradigms, and suggested that the antiepileptic effects of stimulation were mediated mostly by short-term synaptic depression of excitatory neurotransmission.

scholarly journals Degradation of Temporal Resolution in the Auditory Midbrain After Prolonged Deafness Is Reversed by Electrical Stimulation of the Cochlea

2005 ◽  
Vol 93 (6) ◽  
pp. 3339-3355 ◽  
Author(s):  
Maike Vollmer ◽  
Patricia A. Leake ◽  
Ralph E. Beitel ◽  
Stephen J. Rebscher ◽  
Russell L. Snyder
Keyword(s):  
Electrical Stimulation ◽  
Auditory System ◽  
Temporal Resolution ◽  
Central Nucleus ◽  
Central Auditory System ◽  
Auditory Midbrain ◽  
Chronic Stimulation ◽  
Spiral Ganglion Cell ◽  
Chronic Electrical Stimulation

In an animal model of prelingual deafness, we examined the anatomical and physiological effects of prolonged deafness and chronic electrical stimulation on temporal resolution in the adult central auditory system. Maximum following frequencies ( Fmax) and first spike latencies of single neurons responding to electrical pulse trains were evaluated in the inferior colliculus of two groups of neonatally deafened cats after prolonged periods of deafness (>2.5 yr): the first group was implanted with an intracochlear electrode and studied acutely (long-deafened unstimulated, LDU); the second group (LDS) received a chronic implant and several weeks of electrical stimulation (pulse rates ≥300 pps). Acutely deafened and implanted adult cats served as controls. Spiral ganglion cell density in all long-deafened animals was markedly reduced (mean <5.8% of normal). Both long-term deafness and chronic electrical stimulation altered temporal resolution of neurons in the central nucleus (ICC) but not in the external nucleus. Specifically, LDU animals exhibited significantly poorer temporal resolution of ICC neurons (lower Fmax, longer response latencies) as compared with control animals. In contrast, chronic stimulation in LDS animals led to a significant increase in temporal resolution. Changes in temporal resolution after long-term deafness and chronic stimulation occurred broadly across the entire ICC and were not correlated with its tonotopic gradient. These results indicate that chronic electrical stimulation can reverse the degradation in temporal resolution in the auditory midbrain after long-term deafness and suggest the importance of factors other than peripheral pathology on plastic changes in the temporal processing capabilities of the central auditory system.

Sign in / Sign up

Export Citation Format

Share Document