A behavioral study on electrical stimulation of the cochlea and central auditory pathways of the cat

Electrical stimulation of afferent auditory elements through electrodes placed in the middle ear was investigated in acute guinea pig preparations. Thresholds for auditory activation were current-dependent for low frequencies (<1 kHz) and charge-dependent at higher frequencies. Threshold currents were 3–5 times those for intracochlear stimulation. Mechanisms of activation were examined with removal of cochlear fluids and injection of neomycin, Xylocaine, saline, and artificial perilymph with different calcium concentrations. Neurons of the spiral ganglion are indicated as mediators of this stimulation.

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Changes in Prefrontal Cortex–Thalamic Circuitry after Acoustic Trauma

Biomedicines ◽

10.3390/biomedicines9010077 ◽

2021 ◽

Vol 9 (1) ◽

pp. 77

Author(s):

Kristin M. Barry ◽

Donald Robertson ◽

Wilhelmina H. A. M. Mulders

Keyword(s):

Electrical Stimulation ◽

Prefrontal Cortex ◽

Auditory System ◽

Acoustic Trauma ◽

Neuron Activity ◽

Compensatory Mechanism ◽

Efferent Connections ◽

Medial Geniculate ◽

Central Auditory Pathways ◽

Stimulation Of

In the adult auditory system, loss of input resulting from peripheral deafferentation is well known to lead to plasticity in the central nervous system, manifested as reorganization of cortical maps and altered activity throughout the central auditory pathways. The auditory system also has strong afferent and efferent connections with cortico-limbic circuitry including the prefrontal cortex and the question arises whether this circuitry is also affected by loss of peripheral input. Recent studies in our laboratory showed that PFC activation can modulate activity of the auditory thalamus or medial geniculate nucleus (MGN) in normal hearing rats. In addition, we have shown in rats that cochlear trauma resulted in altered spontaneous burst firing in MGN. However, whether the PFC influence on MGN is changed after cochlear trauma is unknown. We investigated the effects of electrical stimulation of PFC on single neuron activity in the MGN in anaesthetized Wistar rats 2 weeks after acoustic trauma or sham surgery. Electrical stimulation of PFC showed a variety of effects in MGN neurons both in sham and acoustic trauma groups but inhibitory responses were significantly larger in the acoustic trauma animals. These results suggest an alteration in functional connectivity between PFC and MGN after cochlear trauma. This change may be a compensatory mechanism increasing sensory gating after the development of altered spontaneous activity in MGN, to prevent altered activity reaching the cortex and conscious perception.

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THE CONSEQUENCES OF DEAFNESS AND CHRONIC INTRACOCHLEAR ELECTRICAL STIMULATION ON THE CENTRAL AUDITORY PATHWAYS

Clinical and Experimental Pharmacology and Physiology ◽

10.1111/j.1440-1681.1998.tb02356.x ◽

1998 ◽

Vol 25 (5) ◽

pp. 303-309 ◽

Cited By ~ 8

Author(s):

Natalie Anne Hardie

Keyword(s):

Electrical Stimulation ◽

Auditory Pathways ◽

Central Auditory Pathways

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Estimates of Essential Neural Elements for Stimulation through a Cochlear Prosthesis

Annals of Otology Rhinology & Laryngology ◽

10.1177/00034894800890s202 ◽

1980 ◽

Vol 89 (2_suppl) ◽

pp. 5-7 ◽

Cited By ~ 38

Author(s):

Ben M. Clopton ◽

Francis A. Spelman ◽

Josef M. Miller

Keyword(s):

Electrical Stimulation ◽

Guinea Pig ◽

Cochlear Nucleus ◽

Ganglion Cells ◽

Spiral Ganglion ◽

Design Parameters ◽

Cochlear Prosthesis ◽

Auditory Pathways ◽

A Site ◽

Stimulation Of

Electrical stimulation of afferent auditory pathways through electrodes placed within and outside of the cochlea were used to study stimulation and design parameters relevant to a cochlear prosthesis. In the acute guinea pig preparation, the tract response evoked in brachium of the inferior colliculus by electrical stimulation to an ear provided estimates of the effectiveness of various electrode placements. Stimulation between an electrode in the cochlea and a site along the eighth nerve was characterized by the lowest thresholds Stimulation between intracochlear electrodes was somewhat less effective, and stimulation between external electrodes at the nerve, cochlear nucleus, or distant point was least effective. Thresholds, expressed as current, rose at approximately 6 dB per octave for stimulus frequencies from 1 kHz to 16 kHz. Thresholds below 10 μ A rms were seen for optimal placements. These observations suggest that the neural elements being stimulated are the cell bodies of the spiral ganglion cells.

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