Journal of neurophysiology
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1. The depletion of both norepinephrine (NE) and acetylcholine (ACh) in the visual cortex can decrease plasticity. This decrease in plasticity, although dramatic under some circumstances, fails to occur under others. 2. ⋯ Perhaps the importance of the side of the deprived eye can be explained by assuming that depletion of NE and ACh removes facilitatory input. This would decrease the ability of cortical cells on the side with lesion to potentiate the input from the nondeprived eye relative to the deprived eye; that is, it would decrease the molecular deprivation (MD) effect. A removal of facilitation would also increase the visual input required to drive cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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1. Multiple site optical recording of transmembrane voltage (MSORTV), together with conventional extracellular electrophysiological techniques were utilized with in vivo and in vitro preparations of the olfactory bulb of the Atlantic skate Raja erinacea to analyze electrical activity simultaneously in layers deep to the glomerular layer. 2. In the living animals and the in vitro isolated olfactory bulb, orthodromic stimulation evoked a compound action potential in the olfactory nerve fibers, followed by a series of early field-potential waves (N1, P1, N2, P2, N3, and N4). ⋯ Just threshold orthodromic stimuli evoked an intermediate period of facilitation of the slow signals. A similar period was also observed in the N2 wave of the field potential. 7. Calcium channel blockers such as cadmium ion, or a low Ca2+ medium, suppressed the slow optical component whether evoked by orthodromic, antidromic, or direct stimulation. gamma-Aminobutyric acid (GABA) and baclofen also reduced or blocked the slow component of the extrinsic absorption signal.(ABSTRACT TRUNCATED AT 400 WORDS)
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1. Diffuse noxious inhibitory controls (DNIC) were compared in control sham-operated rats and in rats with lesions of mesencephalic structures involved in the modulation of pain, namely the periaqueductal gray (PAG), cuneiformis nucleus (CNF), and parabrachial nucleus (PB). 2. Lesions were induced by ibotenic acid: 4 micrograms (0.2 microliter) injected bilaterally in the PAG or the CNF-PB area or 10 micrograms (0.5 microliter) injected unilaterally in the CNF or PB. ⋯ We conclude that the PAG, CNF, and PB, three structures that are putatively involved in the modulation of pain, do not participate directly in the supraspinal part of the loop subserving DNIC. The involvement of other structure(s) and a possible indirect modulation of DNIC are discussed. It is also concluded that the PAG, CNF, and PB do not participate directly in the tonic descending inhibitory controls, which are presumed to modulate the activity of convergent neurons.
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1. The biosonar signal (pulse) of the mustached bat, Pteronotus parnellii parnellii, has four harmonics (H1-4), each consisting of a long constant-frequency component (CF1-4) followed by a short frequency-modulated component (FM1-4). As the bat approaches a target, it systematically modifies its pulses to optimize the extraction of information from the echoes. ⋯ They increased their pulse intensity during the backswing. 3) Pulse duration increased from approximately 20 to 23 ms early in the forward swing, decreased to approximately 18 ms as the target was more closely approached, and then increased to 20 ms by the end of the backswing. 4) The instantaneous repetition rate increased from approximately 17 pulses/s at the start of the forward swing to approximately 28 pulses/s near the target, then decreased to approximately 10 pulses/s by the end of the backswing. Pulses usually occurred in trains of 1-2 pulses, with longer trains occasionally occurring near the target. 3. The maximum DS on the pendulum was 1.34 kHz, and the maximum DS compensation was 146 +/- 98 (SD) Hz less than this value.(ABSTRACT TRUNCATED AT 400 WORDS)