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Biomedical subjects

C Elberling

Publications and source records attributed to C Elberling.

At least 55 records · Page 3Linked to original sources
PubMed1980

Middle components of the auditory evoked response in bilateral temporal lobe lesions. Report on a patient with auditory agnosia.

An investigation of the middle components of the auditory evoked response (10--50 msec post-stimulus) in a patient with auditory agnosia is reported. Bilateral temporal lobe infarctions were proved by means of brain scintigraphy, CAT scanning, and regional cerebral blood flow measurements. The middle components were found to be normal regarding latency (pa approximately 30 msec) and configuration of the recordings, when evaluated relative to the peripheral hearing loss in the patient and to the corresponding normative template. Based upon the combined procedures, it is concluded that the middle components cannot be generated exclusively, if at all, in the primary auditory cortex, located in the temporal lobe. Furthermore, the responses are found to be of neurogenic origin according to the methodological procedure applied.

Aged↗
PubMed1980

Magnetic auditory responses from the human brain. A preliminary report.

By means of a magnetic sensor, SQUID (Superconducting Quantum-Interference Device) the late acoustically evoked magnetic field was recorded from the right and left side of the skull in 5 humans in response to ipsi- and contralateral 1 kHz tone bursts at 80 dB SPL. The '100 ms' component of the magnetic field has opposite polarity on the two sides of the head and when crossing the primary auditory cortex at the Sylvian fissure in a posterior--anterior track, polarity inversion of this component takes place within a highly localized region. The evoked magnetic field is widely distributed across the scalp and seems to be produced by an equivalent magnetic dipole located in or near the primary auditory cortex. In the present experiment neither right--left hemisphere nor ipsi--contralateral differences could be demonstrated.

Audiometry↗
PubMed1979

Auditory electrophysiology. The use of templates and cross correlation functions in the analysis of brain stem potentials.

A method for the objective analysis of acoustically evoked brain stem potentials, BSER, is proposed. Recordings from 24 patients with pure cochlear hearing losses are adjusted in amplitude and time, and used to produce normative BSER waveforms serving as templates. The cross-correlation function between the individual, adjusted BSER recording and the corresponding template is calculated, yielding an objective measure of the BSER waveform and gross latency. Clinical application of the method has given encouraging results.

Brain Stem↗
PubMed1978

Estimation of the critical bandwidth from loudness summation data.

An automatic method for critical band estimation from loudness summation data is presented. A mathematical model, based on a power function, is fitted to the data and the critical bandwidth is defined at the intersection of the asymptotes. The model is designed for clinical use, involving the treatment of the data from single test persons; it represents an operational solution to a difficult task. The model is able to describe data from normals and patients with a sensorineural hearing loss. Variability of the critical band estimates, intrasubject as well as intersubject, is larger than for visually obtained estimates. However, visual estimation is difficult, subjective, and probably heavily biased. The model produces estimates which in logarithmic form have a Normal distribution at medium loudness level, while visual estimation gives rise to irregular distributions at all levels. A normal range for model estimates from sets of data obtained at medium loudness level is defined by mean and standard deviation.

Auditory Perception↗
PubMed1978

Compound impulse response for the brain stem derived through combinations of cochlear and brain stem recordings.

To overcome some of the problems involved in the application of brain stem evoked responses (BSER) in otoneurological diagnosis an approach is developed which combines cochlear and brain stem recordings. The activity of the cochlea and brain stem generators, as seen from the far-field recording electrode, is considered to be the output from a single system. The impulse response of this system can be derived through deconvolution of the brain stem evoked responses, BSER, with the compound action potential, AP, followed by appropriate filtering. This method is used on the recordings from 15 subjects with various degrees of cochlear hearing loss. The results show that the compound impulse response, CIR, for the brain stem consists of five recognizable peaks. From the individual subjects this response pattern is largely independent of intensity. By plotting the amplitude and latency of the individual peaks for all 15 subjects a set of normative data is retrieved. The variation in the data is small, probably because interfeerence from the periphery is eliminated and the separation of activity from the different brain stem generators is improved.

Audiometry↗
PubMed1978

Decoding of human compound action potentials.

The physiological formation of the action potentials is presumed to be well-known and a method of decoding these potential is therefore based on this knowledge. The method uses the reverse process, i.e. deconvolution of the recorded AP's with a unit response, and a subsequent nonlinear transformation of the obtained waveforms (sigma PST-compound PST) from the time- into the location domain (distance along the coclear partition). The transformed waveforms are called excitation patterns. Stimulus polarity seems to have only a minor influence on the excitaton patterns and it is possible to produce frquency-specific information of the coclear function. A clinical case demonstrates the concordance between the excitation patterns and the puretone audiogram.

Acoustic Stimulation↗