introduction: previously, we demonstrated that i.p. injection of aqueous extract prepared from aerial parts of drosera spatulata (droseraceae) can induced remarkable analgesia in both phases of formalin test in rats. because, analgesia induced in acute phase of formalin test mainly mediated by activation of central analgesic mechanisms and also paragigantocellularis (pgi) nucleus is part of bra...

In the rat, doses of glucose sufficient to raise glucose concentrations in the blood to levels equivalent to those produced by a meal or stress suppress the firing of dopamine-containing neurons located within the substantia nigra. Glucose also prevents or reverses the increase in discharge rates of dopaminergic cells normally elicited by the antipsychotic agent haloperidol.

Although there is general consensus that deep brain stimulation (DBS) yields substantial clinical benefit in patients with Parkinson's disease (PD), the therapeutic mechanism of DBS remains a matter of debate. Recent studies demonstrate that DBS targeting the globus pallidus internus (GPi-DBS) suppresses pathological oscillations in firing rate and between-cell spike synchrony in the vicinity o...

In cortical neurons, the arrival of a spike from one input may or may not be correlated with the arrival of other spikes from different inputs. We asked how the firing rate and variability of a postsynaptic neuron vary as functions of the correlations between its input spike trains. We developed a stochastic model in which the membrane potential performs a random-walk toward threshold, and deri...

The effects of local pressure application of the selective GABA(A) antagonists, bicuculline, gabazine, and picrotoxin, and the selective GABA(B) antagonists, 2-OH-saclofen and CGP-55845A, on the spontaneous activity of electrophysiologically identified substantia nigra dopaminergic neurons were recorded in vivo in urethane anesthetized rats. Blockade of GABA(A) inputs by bicuculline powerfully ...

Vagus nerve stimulation (VNS) is an antiepileptic treatment, which has recently shown promise as an antidepressant. Yet, its antidepressant mechanisms of action are unknown. Serotonergic [5-hydroxytryptamine (5-HT, serotonin)] and noradrenergic [norepinephrine (NE)] systems are involved in the pathophysiology of depression and in the mechanisms of action of antidepressants. The present study an...

The progressive ratio (PR) schedule of reinforcement is used to determine the reinforcing properties of rewards such as drugs of abuse. In this schedule, the animal is required to press a lever a progressively increasing number of times to receive a reward; the highest ratio obtained before the animal ceases responding is termed "breakpoint." We recorded neuronal spike activity from cells in th...

To examine the role of striatal mechanisms in cocaine-induced stereotyped licking, we investigated the acute effects of cocaine on striatal neurons in awake, freely moving rats before and after cocaine administration (0, 5, 10, or 20 mg/kg). Stereotyped licking was induced only by the high dose. Relative to control (saline), cocaine reduced lick duration and concurrently increased interlick int...