Ulises M. Ricoy, Ph.D.
Ph.D. The University of Texas at San Antonio
M.A. The University of Texas at San Antonio
B.S. The University of Texas at San Antonio
My current focus is to examine at the cellular level (extracellular and intracellular responses) the potential mechanisms the hippocampus may be mediating to produce the local methamphetamine-induced effect observed in my doctoral dissertation. This will be accomplished by examining the role of various biogenic amines that are elevated during methamphetamines' broad mechanism of action on biogenic amines such as catecholamines (Dopamine, Norepinephrine), Epinephrine and Indolamines (Serotonin and Histamines).
Interestingly, histamine agonists have been strongly implicated in the wakefulness / arousal states and extremely important for regulating sleep cycles. On the other hand, the common secondary effect of anti-histamines is their drowsiness effects. Not surprisingly, amphetamines are a commonly prescription to people with sleep disorders such as Narcolepsy. The exact role amphetamines exert via various neuromodulators to ultimately change synaptic transmission and synaptic output (synaptic dynamics) in the hippocampus is not fully understood and thus the current focus of my research.
Synaptic output is a highly dynamic, owing to the existence of several forms of activity-dependent synaptic plasticity that range in duration from milliseconds to hours. Although individual forms of synaptic plasticity have been well described, the simple stimulus patterns used to define each form of plasticity bear little resemblance to the activity patterns seen in vivo, where most synapses are activated by temporally complex patterns of afferent firing. These complex patterns of activity are expected to engage several forms of synaptic plasticity. Therefore, I will use field and whole-cell recordings to measure synaptic responses to spike trains derived from activity patterns seen in CA3 pyramidal cells in vivo during the performance of a complex behavioral task. The role of Histamine will be examined in Hippocampal synaptic dynamics. Synaptic transmission will be examined in the Schaeffer-Collaterals (SC) to CA1 synapses by stimulating the SC and recording extracellular field potentials in the stratum radiatum and lacunosum moleculare of CA1 region in vitro.