Reaction Time Of Rats Research Articles

Visual Discrimination Accuracy across Reaction Time in Rats

Visual Discrimination Accuracy across Reaction Time in Rats

Analgesic and Anti Inflammatory Activity of the Leaves of Caryota urens Linn.

Caryota urens Linn (Palmae) commonly known as Sugar palm is used in traditional medicine to treat hemicrania and rheumatic swelling. Methanolic extract of plant leaves was used to perform analgesic and anti inflammatory activity. Analgesic study was performed by hot plate and tail flick method and anti-inflammatory effect analyzed by carrageenan induced paw edema. The methanol extract produced significant dose-dependent inhibition of carrageenan-induced rat paw edema. The extract also showed marked analgesic activity. In both the model of analgesic activity methanolic extract of Caryota urens at doses of 200 mg/kg and 400 mg/ kg significantly increase reaction time in rats when compared with control. The dose 400 mg/kg of Caryota urens was highly significant which is comparable with standard in both the studies.Phytochemical investigation of Caryota urens extracts shows presence of phytosterols, tepenoids, flavonoids , tannins and Phenolic compounds which has been responsible for analgesic and anti inflammatory activity. Keywords

Anti-inflammatory and anti-arthritic activity of a methanol extract from Vitellaria paradoxa stem bark.

Background:Vitellaria paradoxa is a traditional medicinal plant of Cameroon. Several studies on this plant have focused on the cosmetic profile of its fruits. The present study focuses on the anti-inflammatory potency of stem barks extract of this plant.Objective:The objective was to evaluate the effect of methanolic extract of V. paradoxa (VPME) stem barks on inflammatory response in rats.Materials and Methods:Anti-inflammatory effects of VPME were evaluated in acute and chronic (28 days) inflammation induced in Wistar albino rats. The effects on hyperalgesia and locomotors activity were also quantified. The relative weight of lymphoid organs was obtained as well as some hematological parameters.Results:In the carrageenan-induced inflammation, VPME (75 mg/kg) exhibited a significant (66.67%) inhibition after 1 h. On the complete Freund's adjuvant-induced rheumatoid arthritis, VPME showed a significant protective effect with 8.12% inflammation against 25.00% for the control group after 2 days of the treatment. The extract (75 and 150 mg/kg) significantly reduced the score of arthritis with a maximum obtained on day 19th of the experimentation. There was a significant increase in the reaction time of rats on the hot plate as well as the exploratory activities of the animals in the open field. This extract significantly prevented weight, hemoglobin and red blood cells losses, and spleen hypertrophy. A protective action against skin destruction and cartilage erosion was evident. Liquid chromatography-mass spectrometry analysis of the extract revealed the presence of catechins.Conclusions:These findings suggested that V. paradoxa may contribute to the reduction of the inflammatory response.

Effects of contrast, spatial frequency, and stimulus duration on reaction time in rats.

Early visual processing in rats is mediated by several pre-cortical pathways as well as multiple retinal ganglion cell types that vary in response characteristics. Discrete processing is thereby optimized for select ranges of stimulus parameters. In order to explore variation in response characteristics at a perceptual level, visual detection in rats was measured across a range of contrasts, spatial frequencies, and durations. Rats responded to the onset of Gabor patches. Onset time occurred after a random delay, and reaction time (RT) frequency distribution served to index target visibility. It was found that lower spatial frequency produced shorter RTs, as well as increased RT equivalent of contrast gain. Brief stimulus presentation reduced target visibility, slowed RTs, and reduced contrast gain at higher spatial frequencies. However, brief stimuli shortened RTs at low contrasts and low spatial frequencies, suggesting transient stimuli are more efficiently processed under these conditions. Collectively, perceptual characteristics appear to reflect distinctions in neural responses at early stages of processing. The RT characteristics found here may thereby reflect the contribution of multiple channels, and suggest a progressive shift in relative involvement across parameter levels.

Functional evidence for altered activity of GABAergic receptors following chronic desipramine treatment in rats.

The antinociceptive effect of subcutaneous 4,5,6,7-tetrahydroisoxazol[5,4-c]pyridin-3-ol (THIP) or (+/-)-baclofen, measured as reaction time of rats placed on a plate heated to 55 degrees C, was assessed after a single or the last repeated (18 consecutive days) dose (5 mg kg-1 once daily) of subcutaneous desipramine. Baclofen (10 mg kg-1)-induced antinociception was reduced by acute and unaffected by chronic desipramine treatment. On the contrary, THIP (20 mg kg-1)-induced antinociception was unaffected by acute and reduced by chronic desipramine.

Serotonin Depletion Impairs Waiting but not Stop-Signal Reaction Time in Rats: Implications for Theories of the Role of 5-HT in Behavioral Inhibition

Central serotonin (5-HT) function is thought to be a critical component of behavioral inhibition and impulse control. However, in recent clinical studies, 5-HT manipulations failed to affect stop-signal reaction time (SSRT), which is a fundamental process in behavioral inhibition. We investigated the effect of central 5-HT depletion (intracerebroventricular 5,7-dihydroxytryptamine) in rats on two aspects of behavioral inhibition, SSRT and 'waiting', using the stop-signal task. 5-HT depletion had no effects on SSRT or any other primary measure on the stop-signal task. However, within the same task, there was a deficit in 'waiting' in 5-HT-depleted rats when they were required to withhold from responding in the terminal element of the stop-signal task for an extended period. D-Amphetamine had dose-dependent, but not 5-HT-dependent effects on SSRT. Conversely, the dose that tended to improve, or decrease, SSRT (0.3 mg/kg) impaired the ability to wait, again independently of 5-HT manipulation. These findings suggest that SSRT and 'waiting' are distinct measures of behavioral inhibition, and show that 5-HT is critical for some forms of behavioral inhibition but not others. This has significant implications for the treatment of conditions such as attention deficit and hyperactivity disorder, substance abuse, and affective disorders, in which inhibitory and impulse-control deficits are common.

The effect of caffeine to increase reaction time in the rat during a test of attention is mediated through antagonism of adenosine A 2A receptors

Caffeine produces effects on cognitive function particularly relating to aspects of attention such as reaction time. Considering the plasma exposure levels following regular caffeine intake, and the affinity of caffeine for known protein targets, these effects are likely mediated by either the adenosine A 1 or A 2A receptor. In the present studies, two rat strains [Long-Evans (LE) and CD] were trained to asymptote performance in a test of selective attention, the 5-choice serial reaction time task (5-CSRTT). Next, the effects of caffeine were compared to the selective A 2A antagonists, SCH 412348 and KW-6002 (Istradefylline), and the A 1 antagonist, DPCPX. Further studies compared the psychostimulant effects of each drug. Finally, we tested the A 2A agonist, CGS-21680, on 5-CSRTT performance and given the antipsychotic potential of this drug class, studied the interaction between CGS-21680 and amphetamine in this task. Caffeine (3–10 mg/kg IP) increased reaction time in both LE and CD rats, with no effect on accuracy, an effect replicated by SCH 412348 (0.1–1 mg/kg PO) and KW-6002 (1–3 mg/kg PO), but not DPCPX (3–30 mg/kg PO). At least with SCH 412348, these effects were at doses that were not overtly psychostimulant. In contrast, CGS-21680 (0.03–0.3 mg/kg IP) slowed reaction speed and increased omissions. Interestingly, at a comparatively low dose of 0.03 mg/kg, CGS-21680 attenuated the increased premature responding produced by amphetamine (1 mg/kg IP). The present results suggest that the attention-enhancing effects of caffeine are mediated through A 2A receptor blockade, and selective A 2A receptor antagonists may have potential as therapies for attention-related disorders. Furthermore, the improvement in response control in amphetamine-treated rats following CGS-21680 pretreatment supports the view that A 2A agonists have potential as novel antipsychotics.

Acceleration after-effects on learning and memory in rats: +10 Gz or +6 Gz for 3 min

High sustained positive Gz (+Gz) exposures have been shown to have a pathophysiological impact on the brain in rats. However, the consequence for brain function such as learning and memory remains elusive. In the present study, we investigated locomotor activity, learning ability and memory in rats over 6 days (d) following +6 Gz/3 min and +10 Gz/3 min exposures. In an open field test, rats treated with +10 Gz showed a significant increase in the time spent in the center square immediately and 2d after exposure compared with control rats. In contrast, the number of grid crosses and number of rears of rats decreased significantly immediately after +6 Gz and +10 Gz exposures. In addition, a Y-maze test revealed that +Gz exposures reduced the number of correct responses and increased total reaction time in rats, and the number of correct responses was negatively correlated with the total reaction time in all groups throughout the period of study. Moreover, the passive avoidance test exhibited that the latency increased significantly on 0 d and decreased significantly on 6 d after +Gz exposures compared with control. Thus, +6 Gz/3 min and +10 Gz/3 min exposures may transiently decrease locomotor activity, impair learning, and induce a deficit in memory retention in rats.

Reaction Time Responding in Rats

BLOKLAND, A. Reaction time responding in rats. NEUROSCI BIOBEHAV REV 22(6) 847–864, 1998.—The use of reaction time has a great tradition in the field of human information processing research. In animal research the use of reaction time test paradigms is mainly limited to two research fields: the role of the striatum in movement initiation; and aging. It was discussed that reaction time responding can be regarded as “single behavior”, this term was used to indicate that only one behavioral category is measured, allowing a better analysis of brain–behavior relationships. Reaction time studies investigating the role of the striatum in motor functions revealed that the initiation of a behavioral response is dependent on the interaction of different neurotransmitters (viz. dopamine, glutamate, GABA). Studies in which lesions were made in different brain structures suggested that motor initiation is dependent on defined brain structures (e.g. medialldorsal striatum, prefrontal cortex). It was concluded that the use of reaction time measures can indeed be a powerful tool in studying brain–behavior relationships. However, there are some methodological constraints with respect to the assessment of reaction time in rats, as was tried to exemplify by the experiments described in the present paper. On the one hand one should try to control for behavioral characteristics of rats that may affect the validity of the parameter reaction time. On the other hand, the mean value of reaction time should be in the range of what has been reported in man. Although these criteria were not always met in several studies, it was concluded that reaction time can be validly assessed in rats. Finally, it was discussed that the use of reaction time may go beyond studies that investigate the role of the basal ganglia in motor output. Since response latency is a direct measure of information processing this parameter may provide insight into basic elements of cognition. Based on the significance of reaction times in human studies the use of this dependent variable in rats may provide a fruitful approach in studying brain–behavior relationships in cognitive functions.