Biomedical subjects

C Pantev

Publications and source records attributed to C Pantev.

93 records · Page 6Linked to original sources

PubMedDate not supplied

Relationship of transient and steady-state auditory evoked fields.

Transient and steady-state auditory evoked fields (AEFs) to brief tone pips were recorded over the left hemisphere at 7 different stimulus rates (0.125-39 Hz) using a 37-channel biomagnetometer. Previous observations of transient auditory gamma band response (GBR) activity were replicated. Similar rate characteristics and equivalent dipole locations supported the suggestion that the steady-state response (SSR) at about 40 Hz represents the summation of successive overlapping (10 Hz) middle latency responses (MLRs). On the other hand, differences in equivalent dipole locations and habituation effects suggest that the magnetically recorded GBR is a separate phenomenon which occurs primarily at low stimulus rates and is unrelated to either the magnetically recorded MRL or SSR.

Acoustic Stimulation↗

PubMedDate not supplied

Study of the human auditory cortices using a whole-head magnetometer: left vs. right hemisphere and ipsilateral vs. contralateral stimulation.

Structural and functional asymmetries of the temporal lobe affect language development and may also play a role in a variety of disorders, ranging from specific language impairment to schizophrenia. Whole-head neuromagnetometers allow the noninvasive measurement of functional asymmetries since activity from both hemispheres is recorded simultaneously. In the present study, the location of the auditory cortices and their responsiveness to pure tones was compared between hemispheres in healthy human subjects. Data suggest a greater contralateral than ipsilateral activation. In line with previous findings, sources of responses for the right hemisphere seem to be more anterior than for the left one.

Acoustic Stimulation↗

PubMedDate not supplied

Frequency-specific threshold determination with the CERAgram method: basic principle and retrospective evaluation of data.

A method for the objective evaluation of the hearing threshold using cortical evoked response audiometry was developed. The method results in a kind of objective audiogram, visualizing the significance of an auditory evoked potential (AEP) in a scheme similar to a conventional audiogram. In the present implementation of the method, four frequencies are tested quasi-simultaneously (500, 1000, 2000 and 3000 Hz; intensity steps of 5 dB). The significance of an evoked potential is assessed by means of the Rayleigh test, which is applied to the phase values derived from certain time windows of the single-trial epochs. A retrospective analysis of 1, 920 threshold estimations in 240 subjects suggested that the detection threshold (lowest stimulus intensity yielding a significant response) was, on the average, 7.5 dB above the electrophysiological threshold (intensity where the AEP amplitude vanishes). The grand-average amplitude-intensity characteristic was approximated by the function a(1 - exp(-I/b)), with a = 6.25 microV, b = 22.3 dB and I representing the intensity (in decibels) relative to the electrophysiological threshold.

Auditory Perception↗