Dataset Information

Imaging electrical resonance in hair cells.

ABSTRACT: The mechanosensory hair cells of many auditory receptor organs are tuned by an electrical resonance that increases their responses to stimulation over a narrow band of frequencies. The small oscillations of membrane potential characteristic of this phenomenon have previously been detectable only through intracellular electrode measurements, which are laborious and preclude analysis at the level of an entire sensory organ. We used a voltage-sensitive dye to image hair-cell electrical resonance in an intact preparation of the bullfrog's sacculus, a receptor organ sensitive to low-frequency seismic and auditory stimuli. Imaging revealed distinct populations of hair cells whose resonant response varied with the frequency of transepithelial electrical stimulation. Most of the hair cells in the saccular epithelium in vitro were electrically tuned to stimulation at 25-50 Hz. The frequency dependence of the fluorescence signal was sensitive to pharmacological blockade of large-conductance Ca(2+)-sensitive K(+) channels and to enzymatic digestion. At an elevated concentration of Ca(2+), we observed transient fluorescence signals that probably represented action potentials. The stroboscopic imaging and analysis techniques described here present a general approach for studying subthreshold oscillations in electrically excitable cells.

SUBMITTER: Fisher JA

PROVIDER: S-EPMC3029741 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Imaging electrical resonance in hair cells.

Fisher Jonathan A N JA Kowalik Lukasz L Hudspeth A J AJ

Proceedings of the National Academy of Sciences of the United States of America 20110110 4

The mechanosensory hair cells of many auditory receptor organs are tuned by an electrical resonance that increases their responses to stimulation over a narrow band of frequencies. The small oscillations of membrane potential characteristic of this phenomenon have previously been detectable only through intracellular electrode measurements, which are laborious and preclude analysis at the level of an entire sensory organ. We used a voltage-sensitive dye to image hair-cell electrical resonance in ...[more]

PMID: 21220326

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Project description:Intraoperative magnetic resonance imaging (iMRI) is a tool now commonly used in neurosurgery. Safe and reliable patient care in this (or any other) operating room setting depends on an environment, where electrical noise (EN) does not interfere with the operation of the electronic monitoring or imaging equipment. In this investigation, we evaluated the EN generated by the iMRI system and the anesthesia patient monitor used at this institution that impacts the performance of these two devices.We measured the EN generated by our iMRI-compatible anesthesia patient monitor as detected by the EN analysis algorithm in our iMRI system. We measured the EN generated by our iMRI system during scanning as detected in the electrocardiogram (ECG) waveform of our patient monitor. We analyzed the effects on EN reduction and signal quality of the ECG noise filters provided in our iMRI-compatible anesthesia patient monitor.Our patient monitor generated EN that was detectable by the iMRI EN analysis algorithm; however, this interference was within the iMRI manufacturer's acceptable limits for an iMRI scan (<10% more than background system-level noise). In the clinical case analyzed, the iMRI generated a narrow-band low-frequency (20 Hz) relatively high-energy EN that interfered with the ECG signal of our patient monitor during an iMRI scan. This EN was correlated with the acoustic noise from the iMRI system during the scan and was associated with the radio frequency (RF) and magnetic gradient pulsations of the iMRI system. The integrity of the ECG waveform was nearly entirely lost during a scan. The filters of the ECG monitor diminished but did not entirely eliminate this 20 Hz interference. We found that the filters alter the morphology of the ECG signal, which may make it difficult to identify clinically relevant ECG changes.The EN generated by our anesthesia patient monitor is within acceptable limits for the iMRI system. The iMRI generates EN which renders the ECG unreadable in the most commonly used filter mode. The monitor's filters diminish this noise but also alter the morphology of the ECG waveform. The anesthesiologist must be cognizant of these technical compromises and recognize that adjusting the ECG filters on the monitor is required to obtain a useful ECG signal for patient monitoring during the iMRI scan but that the diagnostic value of the ECG will be reduced.

Dataset Information

Imaging electrical resonance in hair cells.

Publications

Imaging electrical resonance in hair cells.

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