R M Pico

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Various paradigms have been used to assess the capacity of the adult brain to undergo activity-dependent morphological plasticity. In this report we have employed recurrent limbic seizures as a means of studying the effects of this form of enhanced neuronal activity on cellular morphology and, in particular, on the incidence of somatic spines on the dentate(More)
Two versions of the eight-arm radial maze were used to test the working memory abilities of CD-1 mice. In an elevated open-arm radial maze, mice quickly and successfully learned the multiple-choice procedure. However, mice trained in an enclosed-arm radial maze mastered the task only by developing a kinesthetic strategy of response. When a delay was imposed(More)
The place behaviors of intact rats, and of those receiving fornix lesions, were examined in the radial-arm maze. A cue-restricted environment was constructed wherein the location of arms with food rewards were identifiable only by their position in relation to an intermittently rotated 4-cue set. Food obtainment was measured during a procedure in which(More)
Electrolytic lesions of the dentate gyrus hilus have been demonstrated to induce behavioral seizure activity and to result in perturbations in the amount of enkephalin, cholecystokinin, and dynorphin immunoreactivity in the hippocampal mossy fiber system. In the present study, electroencephalographic (EEG) recordings, made from hippocampus contralateral to(More)
Anodal current passed through a stainless-steel electrode, positioned unilaterally in the rat dentate gyrus hilus, will produce recurrent motor seizures and significant changes in the neuronal expression of several messenger RNAs (mRNAs) throughout the full bilateral extent of the hippocampus. The present study quantitatively analyzed electroencephalograms(More)
Two-day-old chicks were injected either intraventricularly or intraperitoneally with saline or a L-prolyl-L-leucyl-glycinamide solution. This C-terminal tripeptide of oxytocin produced retrograde enhancement when injected centrally but not peripherally. Possible memory mechanisms are discussed in light of this peptide's relationship to oxytocin, MSH, and(More)
Experiments were conducted to investigate the dose-related and time-dependent effects of oxytocin on memory for a one-trial conditioned taste aversion task using two-day old chicks. Oxytocin was administered intracerebrally 1 min posttraining to 5 groups of chicks in dose levels differing by a factor of 10 and ranging from 5.0 pg to 50 ng. A second(More)
These experiments expanded earlier work on hyperprolinemic mice which showed learning deficits. The following behavioral tasks were used: step-through, passive avoidance; T-maze acquisition; shuttlebox acquisition, and radial-arm maze. Mouse species included PRO/Re-bb (genetically hyperprolinemic mice) and PRO/Re-aa (congenic nonhyperprolinemic controls)(More)
The ultrastructure of rat dentate gyrus granule cells was examined during, and near the termination of, a period of lesion-induced recurrent limbic seizure activity which has previously been demonstrated to stimulate dramatic changes in the biosynthetic activities of these neurons. In animals sacrificed 5 h postlesion (or 3.5 h following seizure onset) the(More)
In a single 10-s training trial, hatchling chicks were conditioned to suppress their spontaneous peck response to a small spherical target by coating it with an aversive liquid. A 24-h test trial employing a dry target demonstrated a robust memory for the training manifested in passive avoidance behavior. Leupeptin, a low-molecular-weight antiprotease,(More)