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Full-Text Articles in Medicine and Health Sciences

Radiation Effects On Dopamine-Mediated Prepulse Inhibition In The C57bl/6 Mouse, Cara Nicole Zuccarelli Miller Sep 2003

Radiation Effects On Dopamine-Mediated Prepulse Inhibition In The C57bl/6 Mouse, Cara Nicole Zuccarelli Miller

Loma Linda University Electronic Theses, Dissertations & Projects

This study examined the effects of proton and gamma radiation on a dopamine-dependent sensory gating mechanism: prepulse inhibition of the startle reflex. The purpose of this research was to describe potential hazards of proton radiation to the central nervous system in long-term space fight and for proton therapy patients. Results from previous research indicate that startle behavior is modified by proton and iron radiation. Forty-eight 10-½ week old, male C57BL/6 mice were used to characterize the optimal parameters for the model (prepulse duration, probe duration, and stimulus-onset-asynchrony). Three hundred and fifty two mice were used to characterize the time course …


Time Course Of Loudness Recalibration: Implications For Loudness Enhancement, Yoav Arieh, Lawrence E. Marks Aug 2003

Time Course Of Loudness Recalibration: Implications For Loudness Enhancement, Yoav Arieh, Lawrence E. Marks

Department of Psychology Faculty Scholarship and Creative Works

Loudness recalibration, the effect of a relatively loud 2500-Hz recalibrating tone on the loudness of a relatively soft 2500-Hz target tone, was measured as a function of the interstimulus interval (ISI) between them. The loudness of the target tone, assessed by a 500-Hz comparison tone, declined when the ISI equaled or exceeded about 200 ms and leveled off at an ISI of about 700 ms. Notably, the target tone’s loudness did not change significantly at very short ISIs (<150 ms). The latter result is incompatible with the literature reporting loudness enhancement in this time window but is compatible with the suggestion made by Scharf, Buus, and Nieder [J. Acoust. Soc. Am. 112, 807–810 (2002)] that early measurements of enhancement were contaminated by the influence of the recalibrating tone on the comparison …


Recalibrating The Auditory System: A Speed–Accuracy Analysis Of Intensity Perception, Yoav Arieh, Lawrence E. Marks Jun 2003

Recalibrating The Auditory System: A Speed–Accuracy Analysis Of Intensity Perception, Yoav Arieh, Lawrence E. Marks

Department of Psychology Faculty Scholarship and Creative Works

Recalibration in loudness perception refers to an adaptation-like change in relative responsiveness to auditory signals of different sound frequencies. Listening to relatively weak tones at one frequency and stronger tones at another make the latter appear softer. The authors showed recalibration not only in magnitude estimates of loudness but also in simple response times (RTs) and choice RTs. RTs depend on the sound intensity and may serve as surrogates for loudness. Most important, the speeded classification paradigm also provided measures of errors. RTs and errors can serve jointly to distinguish changes in sensitivity from changes in response criterion. The changes …


Cross-Modal Enhancement Of Perceived Brightness: Sensory Interaction Versus Response Bias, Yoav Arieh, Lawrence E. Marks, Eric C. Odgaard Jan 2003

Cross-Modal Enhancement Of Perceived Brightness: Sensory Interaction Versus Response Bias, Yoav Arieh, Lawrence E. Marks, Eric C. Odgaard

Department of Psychology Faculty Scholarship and Creative Works

Stein, London, Wilkinson, and Price (1996) reported the presence of cross-modal enhancement of perceived visual intensity: Participants tended to rate weak lights as brighter when accompanied by a concurrent pulse of white noise than when presented alone. In the present study, two methods were used to determine whether the enhancement reflects an early-stage sensory process or a later-stage decisional process, such as a response bias. First, the enhancement was eliminated when the noise accompanied the light on only 25% versus 50% of the trials. Second, the enhancement was absent when tested with a paired-comparison method. These findings are consistent with …


The Influence Of Slow Calcium-Activated Potassium Channels On Epileptiform Activity In A Neuronal Model Of Pyramidal Cells, Keun-Hang Susan Yang, Piotr J. Franaszczuk, Gregory K. Bergey Jan 2003

The Influence Of Slow Calcium-Activated Potassium Channels On Epileptiform Activity In A Neuronal Model Of Pyramidal Cells, Keun-Hang Susan Yang, Piotr J. Franaszczuk, Gregory K. Bergey

Mathematics, Physics, and Computer Science Faculty Articles and Research

An imbalance between excitation and inhibition can play an important role in the generation of epileptiform activity. Experimental evidence indicates that alterations of either synaptic activity or intrinsic membrane properties may contribute to this imbalance. The slow Ca2+ - activated K+ currents (sIAHP) limit neuronal firing rate and excitability and are therefore of great interest for their potential role in epileptogenesis. The sIAHP is found in both excitatory and inhibitory neurons, and its effect on these neurons can influence the network behavior. Simulations show that the increased excitability caused by reduction of inhibition by the sIAHP for inhibitory interneuron generates …