Daniel Kueh

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RATIONALE Relatively few studies have compared the discriminative stimulus effects of 3,4-methylenedioxymethamphetamine (MDMA) and cocaine, and findings from different laboratories are somewhat inconsistent. One possible reason for discrepant results may be the use of different reinforcement schedules during discrimination training. OBJECTIVE The present(More)
The central pattern generator for heartbeat in the medicinal leech, Hirudo generates rhythmic activity conveyed by heart excitor motor neurons in segments 3–18 to coordinate the bilateral tubular hearts and side vessels. We focus on behavior and the influence of previously un-described peripheral nerve circuitry. Extracellular recordings from the valve(More)
The heart excitor (HE) motor neuron in the leech Hirudo releases acetylcholine (ACh) and a peptide, FMRFamide, to regulate the contractile activity of the heart tube and associated side vessels. Consistent with Dale's principle, it was assumed that both neurotransmitters were localized to all presynaptic varicosities. However, we found discrete(More)
The dynamics of different ionic currents shape the bursting activity of neurons and networks that control motor output. Despite being ubiquitous in all animal cells, the contribution of the Na(+)/K(+) pump current to such bursting activity has not been well studied. We used monensin, a Na(+)/H(+) antiporter, to examine the role of the pump on the bursting(More)
To achieve the behavioral flexibility necessary for survival in a variable environment, neuronal circuits have to produce activity over a broad range of functional characteristics. Central pattern generators (CPGs), rhythmically active neuronal networks that control motor functions such as breathing, swimming, and walking, are ideal systems for addressing(More)
The formation and refinement of synaptic connections are dependent on the activity that emerges from nascent synaptic connections. Such activity has the effect of regulating the production and release of specific neurotransmitters. To determine the role of activity in regulating the production of peptide-positive synapses, we used antibodies against(More)
The purpose of the present study was to provide further information about the effects of gamma-hydroxybutyrate (GHB) on memory. Initially, the acute effects of gamma-butyrolactone (GBL, 75-200 mg/kg IP), 1,4-butanediol (1,4-BD, 100-300 mg/kg IP), and ethanol (1.0-3.0 g/kg, oral), as well as GHB (100-300 mg/kg IP), were examined in rats responding under a(More)
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