A Role for Hippocampal Neurogenesis in Learning and Memory Essay

Among these different processes are encoding, storage, consolidation, and retrieval. This study hypothesized that the hippocampus plays a different role in each of these. The method of this study is especially unique because it used temporary chemical inactivation of the hippocampus, which had not been done before. This temporary inactivation is unique because it lets the researchers selectively assess the role of the hippocampus during each of the processes discussed above. To test encoding, the inactivation occurred during learning of a maze task; to test retrieval, inactivation occurred during a retention task. Results indicate the temporary inactivation of the hippocampus impairs both encoding and retrieval. To test long-term consolidation, rats were trained and then separate groups received hippocampal treatment for different amounts of time between one and five days. Results showed that temporary inactivation during this time period disrupts memory for the already learned task. This study partially supports the result of the study by Eldridge et al. (2000) in that they both show the hippocampus is necessary for memory retrieval. However, it does not address the retrieval of different types of memory. This study also supports the idea from Wang et al. (2012) that the hippocampus may be involved in consolidation and storage of new memories but not necessarily of older

Hippocampus does not encode the location by the tracking distance and the direction movement. The Direction and distance to the place they need to go is encoded. The brain has its own way of finding there navigational own goal-finding cells. Humans and animals, both of our brains help us find where we need to go and becomes very clear. Scientists know that mammals' brains have three different cell types that help navigate. The animal cells work in the brain and work together to help keep the location and movement they are making. New researchers have discovered two more types of brain cells that also help with navigating around space areas. They have found unrecognized structures in the brain that has to find their way

There is extensive evidence to prove that the hippocampus plays a vital role in memory retrieval. However the extent to what type of memories the hippocampus supports and the process in which retrieval occurs is an ongoing debate. The two theories that are dominant in this debate are the Standard Model of Systems Consolidation (SMSC) and the Multiple Trace Theory (MTT). This paper will provide a review on the evidence supporting these two composing theories, the research providing evidence against the models, and finally their limitations. Additionally, a novel theory coined the Competitive Trace Theory (CTT) will be reviewed in order to conclude whether or not this model can provide a more holistic and accurate representation of the role of the hippocampus in memory retrieval while simultaneously providing explanations for flaws in previously proposed models.

What is the hippocampus? The hippocampus is the formation of memories and a part of the cerebrum.Some people say if you damage the hippocampus you develop a disease called Antevograde amnesia which is the unibaily to form new memories.It also said there are regions that regulates the emotions.

The OED defines multitasking as dealing with more than one task at the same time. The brain, in order to multitask, must receive both actions being performed, and dilute the information before processing. In order to read and listen to something at the same time, for an example, the brain must take the information being read by the eyes and the pulses coming from the ears, and reduce the frequency to keep both tasks going efficiently.

The concept of neurogenesis being confined to the embryonic stage became less obvious with the onset of discovery of neural stem cells maintained in two distinct regions of the mammalian adult brain namely dentate gyrus (DG) of the hippocampus and the sub ventricular zone (SVZ) of the forebrain lateral ventricles14,18,19. What makes these neural stem cells a more credible target for oncogenic transformation? The continual presence of undifferentiated, mitotically active, self renewable stem cells at the apex of the hierarchy bundled in discrete germinal niches in the mammalian brain throughout the lifespan of an organism allows them to accumulate mutations, thus rendering them vulnerable for neoplastic reprogramming. There has been increasing evidence that the genetic and epigenetic mechanisms that initiate and maintain the NSC developmental state are possibly deregulated in GB to emerge as Glioma initiating cells or Brain tumor stem cells20. The discovery of BTSC has high clinical significance in the neuro-oncology field, as evidenced by major diverse roles it plays in various aspects of tumor growth such as tumor initiation, maintenance, progression, angiogenesis and tumor recurrence owing to therapeutic resistance, some of which are described

Steve Ramirez, Xu Liu, Pei-Ann Lin, Junghyup Suh, Michele Pignatelli, Roger L. Redondo, Tomás J. Ryan, Susumu Tonegawa

The hippocampus lies near the center of our brain. It's functions include storing our memories and maintaining a hormone called cortisol. During the time of physical and mental stress, our body releases immoderate amount of cortisol that can create chemical imbalance in the body and cause problem. During depression, long term exposure to increased cortisol level in dentate gyrus (a part of hippocampus) cause hippocampus to shrink as well slow down the production of our neurons. This can lead to memory

Since hippocampus plays an important function in the brain, it has become a great topic for many conducted research not only on human but also animals, specifically primates and rodents. In primate model of amnesia, the experiment is performed through three main tasks – delayed nonmatch to sample, object discrimination paradigm and motor skill learning across multiple trials (Eichenbaum et al, 1992). In delayed non-matching test, both amnesic and intact monkey show nearly same performance rate in remembering objects across delayed in short period of time (Eichenbaum et al, 1992). In contrast, amnesic monkeys show a great impairment for longer delayed conditions, hours, in picking the right non-matched samples (Eichenbaum et al, 1992). Likewise, in object discrimination task, amnesic monkeys are unable to recognize objects, as compared to control monkeys (Eichenbaum et al, 1992).These tests suggest the importance of hippocampus in acquisition of new information and recollection old events from episodic memory. Additionally, hippocampus also contributes largely to relational representation, as a characteristic of declarative memory (Eichenbaum et al, 1992). This can be shown through odor discrimination and place

involved in memory storage. The hippocampus is a place in the brain that is used to

This study investigated the effects of displaced objects and spatial reorganization on habituation of exploratory behavior. The subjects, rats, each individually spent 5 minutes in an open field for 6 trials. Throughout the study, exploratory behavior was measured in the number of contacts the subject made, the number of ambulations, and contact time (seconds). Trials 1-5 were mainly used to familiarize the subject with its surroundings, naturally leading to decreasing amounts of exploratory behavior. Trial 6 involves the same routine, except displaced objects are introduced in an attempt to renew exploratory behavior and promote the building up of environmental maps and representations. Additionally, the measured behavior

To test place-recognition in Experiment 1, after familiarization, the experimenters removed the rats then moved an object to a different location. When the rats were returned, the experimenters measured the time the rats spent exploring the familiar and novel location. The test of object recognition in Experiment 2 resembled that for place recognition. The rats were familiarized and then removed while a familiar object was replaced with an identical replica. The observers measured the time spent exploring the two objects. The movement of the objects in both experiments was done in two versions, a novel-corner-location and a novel-center-location, to control for arena location (center or edge) affecting rat preference for exploration.

To understand the cognitive changes, they further used contextual fear conditioning and radial arm water maze paradigms (RAWM) to study aging effect to hippocampus related learning and memory. Mice injected with young plasma had increased freezing response in contextual, but not cued, learning and showed significant improvement on fear memory. They also exhibited enhancement in learning and memory in finding hidden platform location. On the other hand, no change was observed for aged mice and aged mice injected with aged plasma. Interestingly, these effects were reduced by heat denaturation. Thus, the heat-labile factors from young blood may rejuvenate cognitive ability for the aged mice.

"I lost my keys again," my mother exclaimed at dinner a few nights ago, "I really am getting old." This use of old age as a justification for memory deficits is extremely common. Many people relate old age with loss of memory and other neurobiological functions. Why is it that aging seems to go hand in hand with losing and forgetting things? Is there a neurobiological explanation for this phenomenon?