Neuroreport
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The acoustic startle response is an important mammalian model for studying the cellular mechanisms of emotions and learning. Lesions in the superior olivary complex have been shown to attenuate the amplitude of the acoustic startle response, thus a substantial contribution of these neurons to the startle response was proposed. ⋯ Glutamate uncaging in the olivary complex excited a subpopulation of olivary neurons but never PnC giant neurons, as shown by patch-clamp recordings. This clearly contradicts an excitatory connection from olivary neurons to PnC giant neurons and thus an involvement of the superior olivary complex in eliciting a startle response.
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Blinks are known to change the kinematic properties of fast eye movements, probably by changes in the brain stem circuits. To determine whether slow disconjugate (slow vergence) eye movements are affected by blinks under natural viewing conditions, we elicited airpuff-evoked trigeminal blinks randomly during ongoing steady slow vergence eye movements. ⋯ Slow vergence eye movements showed a peak of vergence velocity during the final part of the blink, which depends on the stimulus direction. We propose that the direction-specific blink effect on slow vergence may be caused by changes in brain stem premotor circuits.
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We have examined the potential role of spinal glial cells in the induction of C fiber-evoked long-term potentiation (LTP) in the spinal cord. Tetanic stimulation of the sciatic nerve induced longterm potentiation of C-fiber-evoked field potentials in the spinal dorsal horn in all rats. ⋯ The effects of fluorocitrate were abolished by kynurenic acid or 2-amino-5-phosphonovaleric acid (AP-5), but not by 6,7-dinitroquinoxaline-2,3-dione (DNQX), picrotoxin or strychnine. These data suggest that spinal glial cells may modulate the central sensitization of nociceptive neurons via NMDA receptors.
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In the auditory cortex, primitive features of acoustic stimuli are represented for auditory scene analysis. A typical example of a feature representation is the tonotopic map, in which sound frequencies are spatially arranged in an orderly manner. Some neurons in the auditory cortex are sensitive to sound source location, which is another important feature for auditory scene analysis. ⋯ The observed arrangements of sound frequencies were consistent with those obtained by electrophysiological mapping, which indicates that our intrinsic optical recording can visualize populational responses of neurons. We also found different temporal patterns of intrinsic signals elicited in response to contralateral, ipsilateral, and bilateral ear stimulations. Finally we try to explain the observed differential time courses of intrinsic signal responses from the theoretical point of view on the conduction of neural activities, based on the so far anatomically identified neural pathways in the rodent auditory system.