Journal of neurophysiology
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The excitatory and inhibitory conductances driving the light-evoked currents (LECs) of cat and ferret ON- and OFF-center X ganglion cells were examined in sliced and isolated retina preparations using center spot stimulation in tetrodotoxin (TTX)-containing Ringer. ON-center X ganglion cells showed an increase in an excitatory conductance reversed positive to +20 mV during the spot stimulus. At spot offset, a transient inhibitory conductance was activated on many cells that reversed near ECl. ⋯ ON-center X ganglion cells receive active excitation during center illumination, and a transient inhibition at light-OFF. In contrast OFF-center X ganglion cells experience a sustained active inhibition during center illumination, and a shorter increase in excitation at light-offset. Cone bipolar cells provide a resting level of glutamate release on X ganglion cells on which their light-evoked currents are superimposed [corrected].
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Flare and hyperalgesia after intradermal capsaicin injection in human skin. J. Neurophysiol. 80: 2801-2810, 1998. ⋯ It is inferred that the cutaneous nerve fibers responsible for the thermographic flare branch, or have coupled axons, over a long distance. The large area of flare coincided with the area of mechanical and heat hyperalgesia. Equivalence of the areas of flare and mechanical and heat hyperalgesia induced by intradermal capsaicin injection suggests that all three phenomena are the consequence of neural factors that operate peripherally.
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Response of anterior parietal cortex to different modes of same-site skin stimulation. J. Neurophysiol. 80: 3272-3283, 1998. ⋯ This was evaluated with the method of correlation mapping. The observations obtained with correlation mapping appear consistent with demonstrations by others that skin-heating stimuli perceived as painful by conscious subjects suppress/inhibit the anterior parietal response to innocuous mechanical skin stimulation. The opposing (relative to the response of area 3a) optical response of area 1 and/or area 3b during skin heating stimulation is attributed to suppression/inhibition of area 1 and/or area 3b neuron activity.
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Chronic changes in synaptic responses of entorhinal and hippocampal neurons after amino-oxyacetic acid (AOAA)-induced entorhinal neuron loss. J. Neurophysiol. 80: 3031-3046, 1998. ⋯ Theta activity was reduced in amplitude in area CA1 and the dentate gyrus of AOAA-treated rats, although evoked responses to angular bundle stimulation could not be distinguished from controls. The results demonstrate that a preferential lesion of layer III of the entorhinal cortex produces a long-lasting change in evoked and spontaneous activity in parts of the entorhinal cortex and hippocampus. Given the similarity of the lesion produced by AOAA and entorhinal lesions in temporal lobe epileptics, these data support the hypothesis that preferential damage to the entorhinal cortex contributes to long-lasting changes in excitability, which could be relevant to the etiology of temporal lobe epilepsy.
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Contribution of supragranular layers to sensory processing and plasticity in adult rat barrel cortex. J. Neurophysiol. 80: 3261-3271, 1998. ⋯ Proportionately fewer neurons in layer IV (52 vs. 64%) and in the infragranular layers (55 vs. 68%) exhibited a clear response bias to paired whiskers. We conclude that receptive-field plasticity can occur in layers IV-VI of barrel cortex in the absence of the supragranular layer circuitry. However, layer I-III circuitry does play a role in normal receptive-field generation and is required for the full expression of whisker pairing plasticity in granular and infragranular layer cells.