Elizabeth García-Pérez

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Most neuronal networks, even in the absence of external stimuli, produce spontaneous bursts of spikes separated by periods of reduced activity. The origin and functional role of these neuronal events are still unclear. The present work shows that the spontaneous activity of two very different networks, intact leech ganglia and dissociated cultures of rat(More)
This study examines the kinetics of the longest lasting form of short-term depression at excitatory hippocampal synapses. After initial depletion of the readily releasable pool (RRP), continued 20-Hz stimulation was found to be fast enough to maximally drive presynaptic neurotransmitter exocytosis; maximal is defined here as the rate needed to maintain the(More)
In the absence of external stimuli, animals explore the environment by performing irregular movements, but the neuronal mechanisms underlying this arrhythmic motion are largely unknown. In this paper, we studied the relationship between the spontaneous neuronal activity in the leech (Hirudo medicinalis) and its behavior. We analyzed the electrical activity(More)
Interactions among chemical and electrical synapses regulate the patterns of electrical activity of vertebrate and invertebrate neurons. In this investigation we studied how electrical coupling influences the integration of excitatory postsynaptic potentials (EPSPs). Pairs of Retzius neurons of the leech are coupled by a nonrectifying electrical synapse by(More)
Animals continuously decide among different behaviors, but, even in invertebrates, the mechanisms underlying choice and decision are unknown. In this article, leech spontaneous behavior was tracked and quantified for up to 12 h. We obtained a statistical characterization, in space and time domains, of the decision processes underlying selection of behavior(More)
At least two rate-limiting mechanisms in vesicle trafficking operate at mouse Schaffer collateral synapses, but their molecular/physical identities are unknown. The first mechanism determines the baseline rate at which reserve vesicles are supplied to a readily releasable pool. The second causes the supply rate to depress threefold when synaptic(More)
OBJECTIVE To determine if levetiracetam (LEV) enhances the impact in excitatory presynaptic terminals of a rate-limiting mechanism in vesicle trafficking termed supply rate depression that emerges to limit synaptic transmission during heavy, epileptiform use. METHODS The effect of LEV was measured with electrophysiologic assays of monosynaptic connections(More)
This paper describes an automatic system for the analysis and classification of leech behavior. Three colored beads were attached to the dorsal side of a free moving or pinned leech, and color CCD camera images were taken of the animal. The leech was restrained to moving in a small tank or petri dish, where the water level can be varied. An automatic system(More)
Short-term plasticity occurs at most central chemical synapses and includes both positive and negative components, but the principles governing interaction between components are largely unknown. The residual Ca(2+) that persists in presynaptic terminals for several seconds after repetitive use is known to enhance neurotransmitter release under artificial,(More)
Local bending, a motor response caused by mechanical stimulation of the leech skin, has been shown to be remarkably reproducible, in its initial phase, despite the highly variable firing of motoneurons sustaining it. In this work, the reproducibility of local bending was further analyzed by monitoring it over a longer period of time and by using more intact(More)