Three-dimensional analysis of auditory-evoked potentials in rat neocortex

1990 ◽  
Vol 64 (5) ◽  
pp. 1527-1536 ◽  
Author(s):  
D. S. Barth ◽  
S. Di
Keyword(s):  
Auditory Cortex ◽  
Evoked Potentials ◽  
Auditory Evoked Potentials ◽  
Microelectrode Array ◽  
Three Dimensional ◽  
Primary Auditory Cortex ◽  
Pyramidal Cells ◽  
Fast Wave ◽  
Cell Groups ◽  
The Right

1. A 8 X 8-channel microelectrode array was used to map epicortical field potentials evoked by bilaterally presented click stimuli from a 8 X 8-mm2 area in the right parietotemporal neocortex of four rats. In two rats, a 16-channel microelectrode array was also inserted into primary auditory cortex to record the laminar profile of auditory evoked potentials (AEP). 2. The epicortical responses began with a positive-negative fast wave followed by a positive-negative slow wave, similar to the previously reported P1, N1, P2, N2 complex. Topographical distributions of the potentials at the peak of each of these waves were distinct, suggesting that they were produced by separate but overlapping populations of cells. 3. Laminar recording revealed the asynchronous participation of supragranular and infragranular pyramidal cells in the generation of the evoked-response complex. The surface-recorded P1 was primarily produced by supragranular cells and the N1, by infragranular cells. The P2 and N2 were produced by temporally overlapping contributions from both cell groups. 4. We conclude that middle-latency components of the AEP complex are produced by both sequential and parallel activation of subpopulations of pyramidal cells in primary auditory cortex.

scholarly journals Competition for neuronal resources: how hallucinations make themselves heard

2007 ◽  
Vol 190 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Daniela Hubl ◽  
Thomas Koenig ◽  
Werner K. Strik ◽  
Lester Melie Garcia ◽  
Thomas Dierks
Keyword(s):  
Auditory Cortex ◽  
Evoked Potentials ◽  
Auditory Evoked Potentials ◽  
Primary Auditory Cortex ◽  
Auditory Attention ◽  
Auditory Hallucinations ◽  
Auditory Stimuli ◽  
Simultaneous Occurrence ◽  
Auditory Verbal Hallucinations ◽  
External Stimuli

BackgroundHallucinations are perceptions in the absence of a corresponding external sensory stimulus. However, during auditory verbal hallucinations, activation of the primary auditory cortex has been described.AimsThe objective of this study was to investigate whether this activation of the auditory cortex contributes essentially to the character of hallucinations and attributes them to alien sources, or whether the auditory activation is a sign of increased general auditory attention to external sounds.MethodThe responsiveness of the auditory cortex was investigated by auditory evoked potentials (N100) during the simultaneous occurrence of hallucinations and external stimuli. Evoked potentials were computed separately for periods with and without hallucinations; N100 power, topography and brain electrical sources were analysed.ResultsHallucinations lowered the N100 amplitudes and changed the topography, presumably due to a reduced left temporal responsivity.ConclusionsThis finding indicates competition between auditory stimuli and hallucinations for physiological resources in the primary auditory cortex. The abnormal activation of the primary auditory cortex may thus be a constituent of auditory hallucinations.

scholarly journals Role of Mammalian Auditory Cortex in the Perception of Elementary Sound Properties

2001 ◽  
Vol 85 (6) ◽  
pp. 2350-2358 ◽  
Author(s):  
Sanjiv K. Talwar ◽  
Pawel G. Musial ◽  
George L. Gerstein
Keyword(s):  
Auditory Cortex ◽  
Time Course ◽  
Auditory Evoked Potentials ◽  
Mammalian Species ◽  
Sound Intensity ◽  
Primary Auditory Cortex ◽  
Normal Hearing ◽  
Auditory Task ◽  
Experimental Conditions

Studies in several mammalian species have demonstrated that bilateral ablations of the auditory cortex have little effect on simple sound intensity and frequency-based behaviors. In the rat, for example, early experiments have shown that auditory ablations result in virtually no effect on the rat's ability to either detect tones or discriminate frequencies. Such lesion experiments, however, typically examine an animal's performance some time after recovery from ablation surgery. As such, they demonstrate that the cortex is not essential for simple auditory behaviors in the long run. Our study further explores the role of cortex in basic auditory perception by examining whether the cortex is normally involved in these behaviors. In these experiments we reversibly inactivated the rat primary auditory cortex (AI) using the GABA agonist muscimol, while the animals performed a simple auditory task. At the same time we monitored the rat's auditory activity by recording auditory evoked potentials (AEP) from the cortical surface. In contrast to lesion studies, the rapid time course of these experimental conditions preclude reorganization of the auditory system that might otherwise compensate for the loss of cortical processing. Soon after bilateral muscimol application to their AI region, our rats exhibited an acute and profound inability to detect tones. After a few hours this state was followed by a gradual recovery of normal hearing, first of tone detection and, much later, of the ability to discriminate frequencies. Surface muscimol application, at the same time, drastically altered the normal rat AEP. Some of the normal AEP components vanished nearly instantaneously to unveil an underlying waveform, whose size was related to the severity of accompanying behavioral deficits. These results strongly suggest that the cortex is directly involved in basic acoustic processing. Along with observations from accompanying multiunit experiments that related the AEP to AI neuronal activity, our results suggest that a critical amount of activity in the auditory cortex is necessary for normal hearing. It is likely that the involvement of the cortex in simple auditory perceptions has hitherto not been clearly understood because of underlying recovery processes that, in the long-term, safeguard fundamental auditory abilities after cortical injury.

Multi-electrode array for measuring evoked potentials from surface of ferret primary auditory cortex

1995 ◽  
Vol 58 (1-2) ◽  
pp. 209-220 ◽  
Author(s):  
Anthony L. Owens ◽  
Timothy J. Denison ◽  
Huib Versnel ◽  
Milton Rebbert ◽  
Martin Peckerar ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Evoked Potentials ◽  
Electrode Array ◽  
Primary Auditory Cortex ◽  
Multi Electrode Array

scholarly journals Brainstem auditory evoked potentials after irradiation of nasopharyngeal carcinoma—Report on two cases with myelopathy of the brainstem

1988 ◽  
Vol 102 (12) ◽  
pp. 1142-1146 ◽  
Author(s):  
S. K. Lau ◽  
W. I. Wei ◽  
D. Choyt ◽  
J. S. T. Sham ◽  
U. C. G. Engzell
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Evoked Potentials ◽  
Auditory Evoked Potentials ◽  
Brainstem Auditory Evoked Potentials ◽  
Post Irradiation ◽  
First Case ◽  
Gag Reflex ◽  
Latency Interval ◽  
The Right ◽  
Unilateral Vocal Cord Paralysis

abstractBrainstem auditory evoked potentials (BAEP) were recorded in two patients with nasopharyngeal carcinoma (NPC) irradiated 14 and three years ago respectively and compared with 15 healthy controls. The patients had features of post- irradiation myelopathy of the brainstem with reduced gag reflex, unilateral vocal cord paralysis and fasciculation of the tongue. The first patient had a blind left eye. The second patient had quadriparesis. All ears revealed post-irradiation otitis media changes and mixed deafness. BAEP was not recognizable in the left ear of the first patient and was normal in the left ear of the second patient. Simultaneous electrocochleogram and BAEP were recorded from the right ear of the first case. The wave I–V latency interval were rolonged in both right ears. In the absence of local recurrence and brain secondaries, these BAEP changes are attributed to the post-irradiation myelopathy of brainstem.

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