Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Auditory Cortex”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,405 records · Page 78Linked to original sources
PubMed2004

One set of sounds, two tonotopic maps: exploring auditory cortex with amplitude-modulated tones.

OBJECTIVE: The possibility of simultaneously observing activation of primary and secondary auditory cortices has been demonstrated by Engelien et al. [Hear Res 2000;148:153-60]. METHODS: Such a dual monitoring by means of neuromagnetic recordings can be achieved when a subject is stimulated by brief pulses of 40Hz-modulated tones. Depending on the frequency filter applied, either the steady-state field (SSF) or the N1m can be extracted from the evoked magnetic field complex. RESULTS: Using this "combined" (two-maps) paradigm with 4 carrier frequencies, we show that it is possible to synchronously screen two tonotopic maps--one map each reflected either by the SSF or the N1m. Indicators are the systematic variation in the location (higher frequencies are more posterior) and orientation (higher frequencies oriented differently in the sagittal plane) of the equivalent current dipole (ECD). These parameters were compared with those obtained from "classic" (one map) paradigms in which either a pure tone elicits an N1m or a 40 Hz continuous (3 s) stimulation produces an SSF. Overall the results were similar, however, systematic differences between the paradigms were found for ECD localization, dipole strength, amplitude, and phase. CONCLUSIONS AND SIGNIFICANCE: One possible interpretation of these results is that different tonotopically arranged cortical fields were involved in the generation of the components.

Acoustic Stimulation↗
PubMed1978

Location of the auditory cortex in the Mongolian gerbil as determined by click stimulation.

An investigation was made of the auditory projection area in the cerebral cortex of the Mongolian gerbil (Meriones unguiculatus) using clicks at a standard intensity to map the cerebral hemisphere by the evoked potential method. The major results can be summarized as follows: (1) As is typical for other mammals, click-evoked responses characterizing the gerbil auditory area were initially surface-positive potentials (amplitudes ranging between 0.1 and 1.7 mV) with peak latencies ranging between 13 and 32 msec. (2) Only one click-responsive field was found in the temporal area. However, the data suggest that this area may actually represent two separate projections to the cortex, since a small subarea characterized by longer response latencies was located posteriorally and laterally within the click field in the majority of animals investigated. (3) The size (5 mm long by 4 mm wide) and location (temporal neocortex below the middle cerebral artery) of the gerbil auditory cortex are consistent with mapping results obtained in other rodent species. (4) The validity of the surface maps was confirmed in four cases by demonstrating that the evoked response reversed polarity between the cortical surface and underlying white matter. The reversal was demonstrated by recording with a penetrating microelectrode at representative points "bordering" the auditory projection area.

Acoustic Stimulation↗
PubMedDate not supplied

Evoked responses of human auditory cortex may be enhanced by preceding stimuli.

We report enhancement of the 100 msec deflection N100m of the auditory evoked magnetic field in paired-stimulus paradigms. Noise bursts of 50 msec duration were delivered in pairs to the left ear at interpair intervals of 1.2-1.4 sec. Stimulus onset asynchrony (SOA) within the pair was either 70, 150, 230, 300, 370 or 500 msec, all intervals being presented randomly within the same block. Magnetic responses were recorded over the right hemisphere with a 7-channel first-order SQUID gradiometer. The mean amplitude of N100m to the second stimulus was maximal at an SOA of about 150 msec, decreasing at longer SOAs to an amplitude about equal to that of the N100m evoked by the first stimulus. Similar enhancement effects were elicited by noise bursts, square-wave tones and sinusoidal tones, by pauses in a continuous noise, and when the two stimuli of a pair were led to different ears.

Auditory Cortex↗