Yehiel Levkovitz

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Hippocampal dentate gyrus reactivity to perforant path (PP) stimulation in the anesthetized rat was enhanced after systemic administration of the serotonin-releasing drug fenfluramine (FFA). This effect of FFA was mimicked by local application of the drug via the recording pipette, indicating that the effect of FFA is mediated by release of serotonin from(More)
Transcranial magnetic stimulation (TMS) has become a promising treatment of affective disorders in humans, yet the neuronal basis of its long-lasting effects in the brain is still unknown. We studied acute and lasting effects of TMS on reactivity of the rat hippocampus to stimulation of the perforant path. Application of TMS to the brain of the anesthetized(More)
BACKGROUND Observations that antagonists of the N-methyl-d-aspartate (NMDA) receptor of glutamatergic neurons can mimic symptoms of schizophrenia have raised the hope that NMDA agonists can improve symptoms. On the basis of encouraging results of trials in which NMDA agonists were added to antipsychotics, we conducted an adequately powered randomized(More)
Cu/Zn superoxide dismutase (SOD-1) is a key enzyme in oxygen metabolism in the brain. Overexpression of SOD-1 in transgenic (Tg) mice has been used to study the functional roles of this enzyme in oxidative stress, lipid peroxidation, and neurotoxicity. We found that Tg-SOD-1 mice are strikingly less sensitive to kainic acid-induced behavioral seizures than(More)
Transcranial magnetic stimulation (TMS) has been proposed as a safe and efficient treatment of human clinical depression. Although its antidepressive mechanism of action remained unknown, our previous studies indicate that TMS has a long-lasting effect on neuronal excitability in the hippocampus. We now compare the effects of chronic TMS with those of the(More)
Transcranial magnetic stimulation (TMS) is being proposed as a method of choice for the treatment of clinical depression, yet its action in the brain is still not well understood. In previous studies we found that TMS has a long-term effect on reactivity of the hippocampus to perforant path stimulation. Since the efficacy of antidepressants is highly(More)
Local modulation of hippocampal-evoked responses to perforant path stimulation was studied by leaking drugs from the recording pipette placed in the dentate gyrus of anesthetized young (3 months old), aging (17 months old) and old (28 months old) rats. In old rats, the excitatory postsynaptic potential (EPSP) slope was much reduced compared to young and(More)
Reactivity of the hippocampal system to stimulation of its main afferent, the perforant path, was studied in the intact, anesthetized rat. Parentral administration of fenfluramine caused a marked elevation of population spike response to perforant path stimulation. An injection of atropine before, but not after fenfluramine, blocked the potentiating effect(More)
Spatial memory ability, tested in a water maze, was severely impaired in control, 24-month-old hooded rats. A daily injection of the serotonin precursor, 5-hydroxytryptophane (5-HTP), prior to training sessions, had no effect on the behavior of the young rats but improved considerably the performance of the old rats in the watermaze. In the same groups of(More)
In previous studies we have demonstrated that raphe grafts, implanted into serotonin-depleted rat hippocampus can restore behavioral and physiological functions impaired by serotonin depletion. Since aging is associated with a reduction in serotonergic functions, we explored the possibility that grafting embryonic raphe tissue will ameliorate age-associated(More)