The impact factors in reward conditioned reflex test of rats / 中国比较医学杂志

Objective To study the effects of different color light stimulus, duration of stimulus and day/night training on the incentive conditioned reflex of rats,and to provide a data basis for the methodology of incentive conditional reflection experiments. Methods Three experiments were included in this study. During the experiment 1, a total of 30 male 8-week-old Wistar rats were divided into three groups:red light stimulation group,yellow light stimulation group and blue light stimulation group. During the experiment 2, a total of 32 male 8-week-old Wistar rats were divided into three groups:the group I(with a light stimulation duration of 10 s), the group II(with a light stimulation duration of 30 s), and the group III(with a light stimulation duration of 60 s). During the experiment 3,a total of 16 male 8-week-old Wistar rats were randomly divided into two groups,of which the first group was trained at 9:00 a.m. every day, and the second group was trained at 21:00 every day. All the laboratory animals were given reward conditioned reflex training, and indicators such as the number of correct nose pokes,the number of incorrect nose pokes,the ratio of correct nose pokes and so on were counted and calculated. Results During the experiment 1,there was no significant difference in the numbers of correct nose pokes and incorrect nose pokes,movement distances and average speeds of the rats among the three groups. During the experiment 2,compared with the group with a light duration of 10 s,the rats in the groups with a light duration of 30 s or 60 s had a higher number of correct nose pokes(P< 0.05). Moreover,on the 13th and 14th days,the ratio of correct nose pokes of the group with a light duration of 30 s was significantly higher than that of the group with a light duration of 10 s(P< 0.001). During the experiment 3,there were no significant differences in the number of correct nose pokes and the nose poke accuracy of the rats between the two groups. Conclusions In the reward conditioned reflex test, red,yellow and blue light stimuli have similar reward prediction effect. When stimulated with the same light, the time of stimulation has an impact on the learning ability of the rats,and an appropriate extension of stimulation is beneficial to the formation of conditioned reflex in them. The day/night training has no effect on the learning and memory ability of the rats.

c-Fos Immunoreactivity in the Neurons of the Lateral Geniculate Nucleus in Albino Rats by Light Exposure after Dark Rearing

PURPOSE: To investigate the effect of dark rearing immediately after birth on the maturation of the visual relay neurons in the lateral geniculate nucleus. METHODS: Fifty neonatal rats were used. Neonates of the control groups were raised under a normal light/dark cycle. Neonates of the experiment groups were dark reared and isolated from light during the entire experimental period, then exposed to the sun light for 1 hour before sacrifice. RESULTS: In the control groups, the neurons in the dorsal lateral geniculate nucleus developed normally at each age tested. In the experiment groups, the cytoplasm of the large neurons in the dorsal lateral geniculate nucleus of 2-week-old rats contained small vesicles, and the cytoplasm of the large neurons of 4-week-old rats was converted into a vacuole-like space. Moreover, c-Fos immunoreactivity of the large neurons in the dorsal lateral geniculate nucleus in the experiment groups was significantly increased compared to that of the control groups. CONCLUSIONS: We suppose that the maturation of the neurons in the lateral geniculate nucleus might be influenced by light stimulation during the critical period. Furthermore, c-Fos could be a marker of the functional activity of the visual relay neurons of the lateral geniculate nucleus in albino rats.

The Changes of short-term memory and Autonomic neurocardiac function after 4-10Hz sound and light stimulation: A pilot study / 수면정신생리

OBJECTIVES: Sound and light (SL) stimulation has been used as a method to induce some useful mental states in the fields of psychology and psychiatry. It is believed that sound and light entrainment device (SLED) has some specific effects through synchronization of EEG in patients who use it. Theta frequency is believed to stimulate deep relaxation and short term memory processing. This study was conducted to evaluate if 4-10Hz SL stimulation can induce relaxation and improve short term memory function. METHODS: Ten medical students with no medical or psychiatric problems participated in this study. Subjects were randomly divided into two groups. One group was applied with real SLED was applied to one group (R group) and pseudo SLED to the other group (P group). The two groups were exposed to SL stimulation with SLED 15 minutes a day for 5 days, and after two days rest the two groups were switched over. The Korea Wechsler Adult Intelligence Scale (K-WAIS), Academic Motivation Tests (AMT), Test Anxiety Scale (TAS), Korea Auditory Verbal Learning Test (K-AVLT), and digit span were used to evaluate short term memory. Spielberger's State-Trait anxiety inventory and heart rate variability (HRV) test were used to evaluate degree of relaxation. RESULTS: Compared with S group, R group showed a significant improvement in K-AVLT and digit span after a single application of SL stimulation. But 5-day long application did not reveal any differences between the two groups. A significant change in HRV was observed in 5-day long application of SL stimulation after being switched over to other SLED. CONCLUSION: This pilot study suggests that 4-10Hz SL stimulation has some positive influences on short term memory and relaxation.

Analysis of Electrically Evoked Potential in Rabbits with Polyimide Retinal Stimulator

PURPOSE: Electrically evoked potential (EEP) was recorded in rabbits with polyimide-based, multichannel, microelectrode array (MEA) in their eyes, and was compared with the visual evoked potential (VEP) by flash light. METHODS: VEP was recorded under full-field flash light stimulation by 0. 6 J at 2 Hz, while EEP was recorded under electrical current stimulation of the retina by MEA. Latencies and shapes of N1, P100 and N2 in each evoked potential were compared. RESULTS: EEP was recorded in four of six rabbits. N1, P100 and N2 were observed in EEP on the electrical retina stimulation over 2.5 mA, and they resembled those of VEP. However, N1, P100 and N2 of EEP showed shorter latencies than those of VEP, by 15.1 msec (32.9%), 76.8 msec (38.3%) and 99.7 msec (60.1%) respectively. CONCLUSIONS: EEP by electrical retina stimulation with MEA was similar to VEP, indicating that MEA is suitable for the development of the artificial retina prototype. The shorter latencies of EEP should be considered in the parameters of the electrical stimulation of the retina.