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I A Vartanyan

Publications and source records attributed to I A Vartanyan.

11 recordsLinked to original sources
PubMed2004

The selectivity of neurons in the auditory zone of the mouse midbrain to the direction of movement of a spectral notch in wide-band noise.

A series of noise signals was synthesized with spectral notches whose central frequencies moved regularly along the frequency range (from low frequencies to high and from high frequencies to low), imitating movement of the sound source in the vertical plane. The spike responses of neurons in the inferior colliculus of the mouse (Mus musculus) to noise signals changed as the spectral notch moved relative to the excitatory and inhibitory areas of the receptive fields of the neurons and depended on the notch width. Disinhibition reactions in the inhibitory zones were more marked when a frequency notch in the inhibitory zone was followed by a frequency notch in the excitatory part of the response. It is suggested that the selectivity of neurons to the direction of movement of the spectral notch in a noise signal is based on the interaction of the excitatory and inhibitory inputs. The overall set of neuron responses can provide information on the movement of the sound source in acoustic space.

Acoustic Stimulation↗
PubMed2004

Activity of neurons in the mouse inferior colliculus in relation to the position and direction of displacement of spectral contrast.

The variability of the responses of neurons in the inferior colliculus of the mouse (Mus musculus) to sequences of signals of noise bands and wide-band noise with spectral notches with regular changes (by 1/12 octave) in the central band frequency or notch frequency was studied. When the width of spectral changes was 1/3 octave, neurons with strong inhibitory influences in the excitatory zone of the response ("inhibition-dependent" neurons) showed low levels of spike activity if the noise band completely covered the excitatory part of the response. The most effective stimuli for these neurons were spectral contrasts passing through the center of the excitatory part of the response (through or close to the characteristic frequency). The responses of neurons to spectral contrasts created by noise bands and noises with notches were identical. It is suggested that approximation of the inhibitory and excitatory inputs sharpens the frequency tuning of neurons to the position of the spectral contrasts, as occurs in the visual system. The selectivity of neurons to the direction of moving spectral contrasts is manifest as a difference in responses when they move from the excitatory area of the response to the inhibitory and vice versa. The functional significance of the contrast mechanism for the analysis of sound source movement based on direction-dependent spectral features associated with the transfer characteristics of the external ear is discussed.

Acoustic Stimulation↗
PubMed1988

Use of amplitude-modulated focused ultrasound for diagnosis of hearing disorders.

Focused ultrasound with a frequency of 2.5 MHz and amplitude-modulated in the range of audiometric frequencies (125-8000 Hz) was employed to examine 50 normal hearing persons and in complex diagnostics of over 500 patients suffering from sensorineural deafness, otosclerosis, chronic otitis media, and acoustic neurinoma. Typical diagnostic signs of these diseases were revealed. Modulated ultrasound is shown to offer an improved diagnosis of hearing diseases. The results confirm the previous observation that amplitude-modulated ultrasound may excite not only the acoustic receptors but also the acoustic nerve fibres. Possible mechanisms of the stimulating effect of focused modulated ultrasound are discussed.

Adult↗