Effects of Lesioned Red Nuclei Essay Example

et al (1996) discovered that cerebellar damage in rats resulted in deficits in both types of skills. This study concentrates specifically on shortcomings identified during the Morris Water Maze test. According to Joyal et al (1996), rats with midline cerebellar damage encountered difficulties in the visual platform condition.

Evidence suggests that rats with lateral cerebellar lesions display motor deficits in the invisible platform segment of the Morris Water Maze, indicating that the cerebellum is involved in processing spatial orientation information. Leggio et al. (2000) studied motor task learning by observing rats. The experimental group observed 200 trials of control rats navigating the Morris Water Maze before undergoing a hemicerebellectomy and being tested in the same maze.

Comparable spatial navigation abilities and escape latencies were found in the rats treated with hemicerebellectomy compared to the control group when observing them in Morris Water Maze. However, significant differences were observed when hemicerebellectomy was performed before observing the control group. This discovery highlights a strong correlation between the cerebellum and spatial processes regardless of task performance. The importance of cerebellum in acquiring and retaining spatial tasks was confirmed as pre-hemicerebellectomy observations could be learned and replicated but not post-hemicerebellectomy. Although other brain regions like prefrontal cortex, posterior parietal cortex, and medial septal area have been studied for their relationship with spatial navigation, no significant results indicate associations with spatial navigation or strategies. Therefore, most studies revealing significant effects on spatial navigation suggest a strong association with the cerebellum.

According to various studies, the cerebellum plays a critical role in spatial navigation, and impairments can occur as a result of damaging Purkinje cells or dentate nucleus lesions (Gandhi et al., 2000; Joyal

et al., 2001). This research aims to examine the effects on spatial navigation caused by damage to the red nucleus. Specifically, it focuses on its significance as a pathway connecting the cerebellum with the thalamus and cerebral cortex. Shepard (1994) suggests that reflexes and muscle tone are primarily controlled by projections from the red nucleus, linking it with spinal cord and reticular nuclei.

Despite the various functions associated with the red nucleus, as evidenced in Lorincz and Fabre-Thrope's (1997) research on cats showing visuo-motor deficits resulting from chemical damage to both the red nucleus and motor thalamus, previous abilities were partially regained over time. Joyal et al.'s (1997) study also observed a similar pattern where deficits were initially present after lesions but gradually improved performance.

The current research investigates the cerebellum's pathway for spatial information, traveling through the red nucleus, thalamus, and cortex. If damage occurs to the red nucleus, the impact on learning the Morris Water Maze task would be similar to Joyal et al.'s 1997 study, indicating that spatial navigation becomes more challenging for lesioned rats. Schizophrenic-like symptoms occur in rats with bilateral red nucleus lesions, making it more difficult to switch spatial navigation strategies. The experiment involved nine male Long Evans Strain rats with access to food and water and kept under 12-hour light-dark cycles. The rats were kept in standard wire mesh cages and fed twice a week. The cages had dimensions, which were approximately...

Nine cages (7.5”W x 10”L x 8”H) were randomly divided into two groups: a red nuclei lesion group (n=4) and a sham group (n=5). All animals underwent surgery, but only four received lesions. The surgeries adhered to aseptic

protocols in accordance with UWM and federal guidelines outlined in the NIH Guide for the Care and Use of Laboratory Animals, and analgesics were administered before and after the surgery.

The animals received Children's Liquid Tylenol at a concentration of 6mg/ml in their water for two days before surgery and three days after surgery, resulting in a total analgesic level of around 700 mg/kg. To induce sedation for the surgical procedure, anesthesia was administered with 4% isoflurane in oxygen at a rate of 4 liters per minute. Throughout the procedure, anesthesia was maintained by using 2% isoflurane in oxygen at a rate of 0.6 liters per minute. Once the anesthesia had been given, each rat was placed on a Knopf Instruments stereotaxic device.

In order to reach the brain, a scalp incision was made and two holes were drilled on either side of bregma - a point located 5.8 mm posteriorly and 0.7 mm mediolaterally from it. Following this, an insulated stainless steel electrode was inserted into the brain and lowered to a depth of around 7.5 mm beneath its surface.

Afterwards, a 1.0 mA direct current was applied to the electrode for 30 seconds. The electrodes were then taken out of both the brain and skull. Next, bone wax was used to fill any holes in the skull and a suture was used to close up the scalp. Finally, the Morris Water Maze apparatus was utilized to assess any visual spatial navigation impairments.

In order to conceal an escape platform from rats for five days, starting on the second day, the circular pool with a diameter of 5 feet and a depth of 20.5

inches was covered with Styrofoam chips. The platform, which had a diameter of 4, was hidden beneath the chips.

Throughout the visual training days (1 and 7), the object was positioned at a height of 5" above the water surface. In contrast, during non-visible acquisition training days (2-6), it was situated 5" below the water surface. The pool was divided into four quadrants: NE, SE, SW, and NW.

During the experiment, the rats were placed on each quadrant's perimeters (N, E, S, W) in the pool and underwent six daily trials. The trials began at different starting points following a clockwise pattern (starting with N, then E, S, etc.). The rats were required to swim continuously for 60 seconds or until they found the platform. If they couldn't locate it within 60 seconds, they were positioned on the platform for five seconds to gain visual cues about its location. After completing this procedure, the rats returned to their cages and prepared for their next trial.

During the behavioral procedure, each rat was given a five-minute break between trials. On the first day, the platform was positioned 5" above the water surface in the SE quadrant to aid visual training and detect any motor or visual impairments. From days 2-4, the platform was moved to the NE quadrant and submerged.

During the experiment, the platform was placed 5 inches beneath the water surface. To prevent the animals from seeing the platform, Styrofoam chips were placed on the water's surface. On days 5 and 6 of the experiment, the platform was moved to the SW quadrant to examine their ability to change spatial searching strategies. On day 7, the platform

remained in the SW quadrant and was raised above the water surface to collect more visual platform data. The statistical analysis was conducted using SAS software.

The experiment involved two Independent Variables, namely surgical condition and training day. The study measured time taken to escape Morris Water Maze as the dependent measure. The dependent variables were considered significant at a p-value of .1. The data from acquisition training days 2, 3, 4, 5, and 6 underwent analysis using a two-way ANOVA with a repeated factor of the second measure, which was the day.

By analyzing the Morris Water Maze data, we determined that there was a significant difference in escape latencies between rats with red nucleus lesions and those who received sham surgeries (F (1,7)=25.14, p=.0015).

The ANOVA analysis looked at the impact of the training day on acquiring the hidden platform, regardless of the surgical condition. The results showed a significant main effect for both training day and escape latency in the Morris Water Maze. The values obtained were F (4,28)=3.64 and p= .0164.

The following are the escape latency duration values for the acquisition period on day 2, day 3, day 4, and day 5: 36.77s, 26.71s, 23.84s, and 23s.

According to the study, the escape latencies varied between day 1 (10s) and day 6 (20.71s). Additionally, there was no noteworthy impact on escape latencies in regards to the interaction between surgical condition and training day (F(4,28)=0.24, p>0.05).

The experiment showed that surgical condition and training days had main effects on escape latencies, but actual surgery did not significantly affect escape latencies during acquisition days. To ensure that the animals had no visual or motor deficiencies that would

hinder their ability to find the platform on days 1 and 7 when it was visible, a second ANOVA was conducted. The results showed that there was a significant main effect for surgical condition on the visible platform days, with an F (1,7) value of 31.

The study yielded two important findings, namely: a primary outcome related to p-value (.0008), and a secondary outcome associated with day of training regarding escape latencies, which had an F-value of 19.05 and a p-value of .0033.

The ANOVA results show that the escape latency for day 1 was 34.65 seconds while it was 12.86 seconds for day 7. Further analysis of the surgical condition and training day interaction revealed that there was no significant main effect (F (1,7) = 1).

According to the results presented in table 5 and paragraph 2606, the rats that underwent surgery did not show a significant difference from the sham rats on visible platform days. This finding increases the researchers' confidence that the main effects observed in this study are not influenced by any visual impairments resulting from the surgery, as discussed in further detail.

A Least Significant Difference (LSD) test was performed, similar to a t-test with an error term from the ANOVA. The test showed no significant effect on the interaction of patterns for leaning in sham and lesioned animals during the training days, indicating similarity. Despite our hypothesis that rats with bilateral lesions of the red nucleus would face difficulty in learning spatial navigation tasks, our results do not support this claim. Additionally, we did not observe schizophrenic-like symptoms when rats switched spatial navigation strategies.

Despite significant main effects for surgical condition and training days

in both ANOVAs, we were unable to identify a significant main effect for the interaction between the two. While Figure 1 shows that lesioned rats had higher escape latency means compared to sham rats during acquisition days, they still demonstrated very similar rates of improvement across training days. Interestingly, on day four, we did not observe an increase in escape latencies in lesioned rats as expected due to difficulties in changing navigation strategies resulting from cerebellar malfunction as seen in schizophrenics; instead, similar strategies were observed in sham rats (Figure 2). These findings suggest that red nucleus lesions do not interfere with navigation strategy switching in rats.

The second ANOVA concerning visual platform days one and seven revealed main effects for the surgical condition and decreases in escape latency means. To ensure that the means did not create a significant effect, we needed to rule out visual or motor deficits not associated with spatial navigation. The results suggest that red nucleus lesions may have caused other visuo-spatial deficits, which put lesioned rats at a disadvantage during visual platform days (Figure 3). However, the interaction between surgical condition and visual platform days one and seven did not produce a main effect. This finding is reassuring because it indicates that the lesioned rats were able to decrease their mean escape latencies across visual training days, just like the sham rats (Figure 4).

The initial assumption that the red nucleus lesioned animals had visuo-motor disabilities is disproved by this discovery. This is because the lesioned animals demonstrated an improvement in their escape latency means compared to the sham rats, although not a significant one (Figure 4). Hence,

this finding supports the idea that the lesioned animals were only relying on their spatial navigation abilities. Furthermore, their larger mean escape latencies are a result of the red nucleus lesions. The first ANOVAs show that surgical conditions have primary impacts and suggest that red nucleus lesions induce similar effects to cerebellum lesions (Joyal, et al 1996). This leads us to conclude that the primary pathway for spatial navigation processing involves the cerebellum passing through the red nucleus to reach the thalamus and eventually the cerebral cortex.

The cerebellum is still believed to play a role in transmitting spatial information, as there were no significant effects seen for interactions between surgical condition and training day. However, it's possible that an additional pathway may assist with visuo-spatial processing. The findings indicate the involvement of the pathway from the cerebellum to the red nucleus to the thalamus in visuo-spatial processing. Further research is necessary to better comprehend other pathways that transmit visuo-spatial information to the thalamus without utilizing the red nucleus. Identifying specific pathways related to visuo-spatial constructs could provide more insight into non-motor functions of the cerebellum.

Enhancing our comprehension of non-motor functions in the cerebellum can enhance our knowledge of disorders connected to the cerebrum, such as schizophrenia's positive and negative symptoms. In Behavioral Neuroscience (111(5), 892-907), Lorincz and Fabre-Thorpe's reference analyzes how simultaneous damage to the motor thalamus and red nucleus impacts a cat's capacity to grasp mobile targets.

The authors of the text are named Gandhi, C. C., Kelly, R. M., and Wiley, R. G., as stated within the HTML

tag.Li, S. et al. (2000) and Walsh, T. J. (2000) wrote about the detrimental

impact of OX7-saporin-induced destruction of cerebellar Purkinje cells on learning in a study titled "Impaired acquisition of a Morris Water Maze task following selective destruction of cerebellar Purkinje cells with OX7-saporin."The reference citation for an article entitled "Behavioural Brain Research" by Joyal and Strazielle is presented with the volume number, issue number, and page numbers enclosed within HTML paragraph tags.The citation for an article titled "Effects of dentate nucleus lesions on spatial and postural sensorimotor learning in rats" by Lalonde and Strazielle (2001) and another by Compton (122(2), 131-137) are included within a paragraph enclosed in a "p" tag.There are a few authors listed: Griffith, H. R., McDaniel, W. F., and Foster, R. The information is contained within a paragraph tag.

Packard and Davis carried out a research in 1997 that investigated the effects of damages to different regions of the brain including the hippocampus, medial septum, prefrontal cortex, and posterior parietal cortex on rats' performance in a water maze test.

The publication "Neurobiology of Learning and Memory" authored by De Bruin, J. P. C. and Sanchez-Santed, F. can be found in volume 68, pages 117-132.

Heinsbroek, R. P. W.; Donker, A.

Leggio, M. G. and Postomes, P. (1994) conducted a study on rats with damage to the medial prefrontal cortex which was published in volume 652, pages 323-333 of Brain Research. The study used the Morris Water Maze and revealed that while the rats displayed behavioural flexibility, their spatial navigation skills were not impaired. The title of the study is "A behavioural analysis of rats with damage to the medial prefrontal cortex using the Morris Water Maze".

The publication in the year 2000 included authors Molinari, M.;

Neri, P.; Graziano, A.; Mandolesi, L.; and Petrosini, L.

Regarding rats, the National Academy of Science published a study titled "Representation of action in rats: The role of cerebellum in learning spatial performances by observation" (Joyal & Meyer, 1998) which examines the relationship between observing external actions and learning spatial performance, with a focus on the cerebellum.

The individuals of Jacquart, G., Mahler, P., Caston, J., and Lalonde, R. are listed within the HTML paragraph tags

.

(1996) M. Rapoport conducted a study on the impact of midline and lateral cerebellar lesions on spatial orientation and motor coordination which was published in Brain Research. The findings have been recorded in volume 739, spanning pages 1-11.

The text provides a selective review of the role of the cerebellum in cognition and behavior and was authored by Schmahmann, J., van Reekum, R., and Mayberg, H. in 2000. The HTML code for this text is

; van Reekum, R.; and Mayberg, H. (2000). The role of the cerebellum in cognition and behavior: A selective review.

.The citation for a journal article by Shepard, G. M. from 1994 in the Journal of Neuropsychiatry and Clinical Neurosciences is provided within a paragraph tag.The chapter on Motor Hierarchies in Nerobiology is available at Oxford University located in New York, USA.