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Optical topography (OT) signals measured during an experiment that used activation tasks for certain brain functions contain neuronal-activation induced blood oxygenation changes and also physiological changes. We used independent component analysis to separate the signals and extracted components related to brain activation without using any hemodynamic(More)
Neuronal activity alters calcium ion (Ca2+) dynamics in astrocytes, but the physiologic relevance of these changes is controversial. To examine this issue further, we generated an inducible transgenic mouse model in which the expression of an inositol 1,4,5-trisphosphate absorbent, “IP3 sponge”, attenuates astrocytic Ca2+ signaling. Attenuated Ca2+ activity(More)
It has been widely accepted that ocular dominance in the responses of visual cortical neurons can change depending on visual experience in a postnatal period. However, experience-dependent plasticity for orientation selectivity, which is another important response property of visual cortical neurons, is not yet fully understood. To address this issue, using(More)
We carried out voltage-sensitive dye imaging of the guinea pig auditory cortex to determine whether the ongoing and spontaneous activities of the cortex exhibit spatial coherence reflecting the tonotopic organization of the cortex. We used independent component analysis and a signal-plus-noise model to extract ongoing activities from the observed signals(More)
  The endocochlear potential (EP) of +80 mV in the scala media, which is indispensable for audition, is controlled by K+ transport across the lateral cochlear wall. This wall includes two epithelial barriers, the syncytium and the marginal cells. The former contains multiple cell types, such as fibrocytes, which are exposed to perilymph on their basolateral(More)
Stria vascularis of the mammalian cochlea transports K(+) to establish the electrochemical property in the endolymph crucial for hearing. This epithelial tissue also transports various small molecules. To clarify the profile of proteins participating in the transport system in the stria vascularis, membrane components purified from the stria of adult rats(More)
Unidirectional K+ transport across the lateral cochlear wall contributes to the endocochlear potential (EP) of +80 mV in the endolymph, a property essential for hearing. The wall comprises two epithelial layers, the syncytium and the marginal cells. The basolateral surface of the former and the apical membranes of the latter face the perilymph and the(More)
Although salicylate is one of the most widely used nonsteroidal anti-inflammatory drugs, it causes moderate hearing loss and tinnitus at high-dose levels. In the present study, salicylate effects on the K currents in inner hair cells were examined. Salicylate reversibly reduced the outward K currents (I(K,f)), but did not affect the inward current (I(K,n)).(More)
Eukaryotic cells exhibit negative resting membrane potential (RMP) owing to the high K+ permeability of the plasma membrane and the asymmetric [K+] between the extracellular and intracellular compartments. However, cochlear fibrocytes, which comprise the basolateral surface of a multilayer epithelial-like tissue, exhibit a RMP of +5 to +12 mV in vivo. This(More)
The cochlea of the mammalian inner ear contains an endolymph that exhibits an endocochlear potential (EP) of +80 mV with a [K+] of 150 mM. This unusual extracellular solution is maintained by the cochlear lateral wall, a double-layered epithelial-like tissue. Acoustic stimuli allow endolymphatic K+ to enter sensory hair cells and excite them. The positive(More)