26 research outputs found
Measuring agreement of administrative data with chart data using prevalence unadjusted and adjusted kappa
YesFunding provided by the Open Access Authors Fund
Interaction between Purkinje Cells and Inhibitory Interneurons May Create Adjustable Output Waveforms to Generate Timed Cerebellar Output
We develop a new model that explains how the cerebellum may generate the timing in classical delay eyeblink conditioning. Recent studies show that both Purkinje cells (PCs) and inhibitory interneurons (INs) have parallel signal processing streams with two time scales: an AMPA receptor-mediated fast process and a metabotropic glutamate receptor (mGluR)-mediated slow process. Moreover, one consistent finding is an increased excitability of PC dendrites (in Larsell's lobule HVI) in animals when they acquire the classical delay eyeblink conditioning naturally, in contrast to in vitro studies, where learning involves long-term depression (LTD). Our model proposes that the delayed response comes from the slow dynamics of mGluR-mediated IP3 activation, and the ensuing calcium concentration change, and not from LTP/LTD. The conditioned stimulus (tone), arriving on the parallel fibers, triggers this slow activation in INs and PC spines. These excitatory (from PC spines) and inhibitory (from INs) signals then interact at the PC dendrites to generate variable waveforms of PC activation. When the unconditioned stimulus (puff), arriving on the climbing fibers, is coupled frequently with this slow activation the waveform is amplified (due to an increased excitability) and leads to a timed pause in the PC population. The disinhibition of deep cerebellar nuclei by this timed pause causes the delayed conditioned response. This suggested PC-IN interaction emphasizes a richer role of the INs in learning and also conforms to the recent evidence that mGluR in the cerebellar cortex may participate in slow motor execution. We show that the suggested mechanism can endow the cerebellar cortex with the versatility to learn almost any temporal pattern, in addition to those that arise in classical conditioning
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Effects of alpha-MSH and beta-endorphin on startle reflex in rat.
Twelve rats received peripheral injections (20 micrograms/rat) of alpha-MSH, beta-endorphin or the vehicle solution and were subsequently tested for the motor and cardiac responses to repeated presentations of intense acoustic stimuli. Each subject received all treatments in a counterbalanced order with 3-day periods between each session. beta-Endorphin tended to decrease the amplitude of the habituated motor startle reflex, while alpha-MSH produced a slight increase in basal heart rate during the habituation session. Neither peptide had any effect on the cardiac response to intense acoustic stimulation. The effects of the two peptides were not directly antagonistic but they are consistent with the hypothesis that complex attentional processes were facilitated by MSH/ACTH fragments and inhibited by the endorphins
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Effects of alpha-MSH and beta-endorphin on startle reflex in rat.
Twelve rats received peripheral injections (20 micrograms/rat) of alpha-MSH, beta-endorphin or the vehicle solution and were subsequently tested for the motor and cardiac responses to repeated presentations of intense acoustic stimuli. Each subject received all treatments in a counterbalanced order with 3-day periods between each session. beta-Endorphin tended to decrease the amplitude of the habituated motor startle reflex, while alpha-MSH produced a slight increase in basal heart rate during the habituation session. Neither peptide had any effect on the cardiac response to intense acoustic stimulation. The effects of the two peptides were not directly antagonistic but they are consistent with the hypothesis that complex attentional processes were facilitated by MSH/ACTH fragments and inhibited by the endorphins
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Effects of melatonin on startle reflex in rat.
In two experiments the effects of melatonin were investigated on the motor, cardiac and emotional components of the startle reflex induced by an intense acoustic stimulus. Melatonin inhibited the motor movements and significantly decreased the HR responses of rats pretested with these procedures. Melatonin decreased the HR responses to stimulation whereas the HR responses of the rats treated with the vehicle solution increased. Melatonin treatment also inhibited the startle-induced defecation compared with the vehicle injection. These findings suggest that melatonin exerts inhibitory effects on the CNS, on sensory reflex and on stress responses
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Effects of melatonin on startle reflex in rat.
In two experiments the effects of melatonin were investigated on the motor, cardiac and emotional components of the startle reflex induced by an intense acoustic stimulus. Melatonin inhibited the motor movements and significantly decreased the HR responses of rats pretested with these procedures. Melatonin decreased the HR responses to stimulation whereas the HR responses of the rats treated with the vehicle solution increased. Melatonin treatment also inhibited the startle-induced defecation compared with the vehicle injection. These findings suggest that melatonin exerts inhibitory effects on the CNS, on sensory reflex and on stress responses
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Naloxone attenuates self-abusive behavior in developmentally disabled clients.
The opiate antagonist naloxone was effective in reducing self-abusive behavior in two mentally retarded clients with an extensive history of such behavior. Three doses of naloxone (0.1, 0.2, 0.4 mg) were compared with a vehicle solution in a double-blind, crossover design. Naloxone greatly attenuated self-abusive episodes in one client and eliminated them entirely in the second client. In addition, use of self-restraining behavior by one client was reduced. The findings suggested that some clients with self-injurious behavior may have disturbances of the endogenous opiate system. Maintenance of self-abuse by tonically elevated pain threshold and/or by the putative addictive characteristics of such behavior was discussed