Synaptic Plasticity 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

PTSD is a disorder that is closely associated with traumatic memories and events. In order to gain a deeper understanding of the biological mechanisms driving PTSD, it is vital to understand the plasticity of memory formation, consolidation, and reactivation. Multiple studies have documented that following the initial memory encoding stage, memory remains temporarily vulnerable to disruption until the consolidation phase (McGaugh, 2000). Diverse corticosteroid compounds (Aerni, et al., 2004) (Schelling, 2002) (Schelling, et al., 2001) (Schelling, et

We assume that if encoding of contextual fear memories require protein synthesis at both hippocampus and PFC, we will be able to identify translationally active mRNAs in hippocampus and PFC. Because RNAs associated with polyribosomes indicate translational activation, we first isolated polyribosomes from mPFC and hippocampus at two time points (one hour and six hours, hereafter T1 and T2

C. APPROACH: Based on our preliminary data on lncRNA changes in specific regions of the brain associated with contextual fear, we hypothesize that specific lncRNAs mediate consolidation and extinction of fear memories. To test this hypothesis, the Puthanveettil and Stackman laboratories will bring together their strong expertise in genomics, bioinformatics, noncoding RNAs, genetics, behavioral models, non-coding RNAs, bioinformatics and functional, in vivo manipulations of novel molecular players. We will employ a research strategy that starts with an unbiased, genome-wide analysis of lncRNAs and funnel down to key players, at which point mechanisms of action will be identified. First, unbiased expression analysis of lncRNAs will be carried out with contextual fear conditioning following extinction of contextual fear memory. Second, we will then carry out in vivo manipulation of specific lncRNAs in specific regions of the brain to determine necessity of the expression of specific lncRNAs in consolidation and extinction of fear memory. We anticipate that our studies will establish the functional importance of candidate lncRNAs in consolidation and extinction and provide novel insights into the novel molecular regulators and mechanisms underlying development of PTSDs. All of the genomics, bioinformatics and rodent behavior analyses will be carried out locally, at Scripps Florida and FAU, with confocal imaging experiments being performed across the street at the Max Planck

lncRNAs are noncoding RNAs that are longer than 200 nucleotides and were identified as a result of large-scale sequencing analyses of transcriptomes and genomes. An increasing number of functional studies indicate that lncRNAs act as regulators in almost every stage of gene expression, from epigenetic modifications in the nucleus to mRNA stability and translation in the cytoplasm. This regulatory potential, along with the abundance of lncRNAs, implies that lncRNAs may be part of a broad epigenetic network. Despite these functional insights, only a small number of lncRNAs have been studied in the nervous system and their contribution to consolidation and extinction of memories is entirely unknown. Because of the transcriptional and translational regulatory roles lncRNAs, elucidating their function in the brain areas implicated in emotional learning and memory may help identify novel therapeutic targets for PTSD. The central hypothesis of this proposal based on our own preliminary studies is that specific lncRNAs mediate consolidation of fear memories and their extinction. To test this hypothesis, we will employ mouse model for fear memories to identify and manipulate specific lncRNAs in vivo with the goal of

Long-term potentiation refers to the steady increase in synaptic activity between two neurons which causes persistent strengthening of synaptic activity. Since memory formation is mainly dependent on synaptic strength, LTP seems to play an essential role in memory formation. Contrary to that, long-term depression causes a reduction in synaptic activity between two neurons, causing a decrease in synaptic activity. LTP and LTD are essential for normal functioning of the brain and balance in the ratio of LTP/LTD is needed for homeostasis. The levels and activity of LTP and LTD are majorly dependent on Calcium levels, Calcium-Calmodulin Kinase, NMDARs (N-Methyl-D-Aspartate receptors) and AMPARs (α-amino-3-hydroxy-5-methylisoxazole-4-propionic

Hippocampus is a small, curved region, which exists in both hemispheres of the brain and plays a vital role in emotions, learning and acquisition of new information. It also contributes majorly to long term memory, which is permanent information stored in the brain. Although long term memory is the last information that can be forgotten, its impairment has become very common nowadays. The dysfunction is exemplified by many neurological disorders such as amnesia. There are two types of amnesia, anterograde and retrograde. Anterograde amnesia is inability in forming new information, while retrograde refers to the loss of the past memory. As suggested by Cipolotti and Bird (2006), hippocampus’s lesions are

After exposure to chronic stress, BDNF levels are increased in the amygdala while they are decreased in the PFC and the hippocampus (Depperman et al., 2014; Mahan & Ressler, 2011). During the consolidation phase, two hours after stress-exposure, BDNF transcription is increased in the amygdala of mice in a fear conditioning paradigm. Even twelve hours after consolidation, increased levels of BDNF were still detected (Mahan & Ressler, 2011). This prolonged increase in BDNF levels in the amygdala after fear conditioning enhances the emotional aspect of traumatic memory and may play a role in the amygdala’s hyperarousal in response to trauma-associated and neutral stimuli (Depperman et al., 2014). Studies of fear extinction in rats have shown that low levels of BDNF are linked to malfunction in both the prelimbic and limbic areas of the PFC (Mahan & Ressler, 2011). Genetically deleting BDNF in the prelimbic area of the PFC causes impairment of consolidation while low expression of BDNF in the limbic area is associated with impaired fear extinction (Mahan & Ressler, 2011). Other studies have looked at deleting BDNF selectively from the hippocampus of mice. The results showed that these mice had impairments in fear extinction, but not fear acquisition (Mahan & Ressler, 2011). Since BDNF

In spite of the promise that manipulations of extinction hold for the PTSD treatments, we know little about the key molecular players regulating consolidation and extinction. We propose to study molecular changes within the CA1 region of hippocampus and prelimbic (Prl) and infralimbic (Infrl) region of medial prefrontal cortex (mPFC). The CA1 is critical for the consolidation of contextual fear and Prl and infrl mPFC are critical for extinction. IncRNAs will be excellent candidates for therapeutics development because lncRNAs have recently been identified as major regulators of gene function through gene-specific modulation of transcription and translation. Several studies have shown that single lncRNAs mediate complex physiological responses. Manipulation of these lncRNAs by knockdown has yielded control of these processes. Hence, modulating specific lncRNAs will likely lead to a beneficial effect on PTSDs. Our studies will provide temporal characterization of changes in the expression of lncRNAs in the CA1, Prl and Infrl during consolidation and extinction to identify novel candidates for the therapeutic manipulation of consolidation and extinction of fear

Synaptic plasticity refers to a process through which the brain undergoes neural changes due to alterations in synaptic strength. Many studies have demonstrated that these synapses have the ability to strengthen or weaken on account of synaptic activity. In other words, an increase in synaptic activity will further strengthen that connection, making it more sensitive to a particular stimulus. Conversely, a decrease in synaptic activity will weaken the connection such that it loses its sensitivity to a given stimulus. The neuronal events that result in the strengthening or weakening of a synapse are explained through two mechanisms – Long-Term Potentiation (LTP) and Long-Term Depression (LTD). In fact, scientists believe that the coupling of these two mechanisms essentially contributes to memory and learning of an individual.

How does memory work? Is it possible to improve your memory? In order to answer these questions, one must look at the different types of memory and how memory is stored in a person's brain.Memory is the mental process of retaining and recalling information or experiences. (1) It is the process of taking events, or facts and storing them in the brain for later use. There are three types of memory: sensory memory, short-term memory, and long-term memory.

Learning is a very important aspect of humans and creatures alike. Not only is it essential to the survival and adaption into this world but it also defines who we are as individuals (Schiller et al, 2010; Tronson & Taylor, 2007). Memories from past experiences shape the people that we are today. A crucial element to learning is memory, without it we would not be able to retain information. The process of memory is very distinct and consists of several different stages: acquisition of memory, consolidation, retrieval and then either reconsolidation or extinction (Debiec & Ledoux, 2004; Diergaarde, Schoffelmeer & De Vries, 2008). As memory is such a critical aspect of learning, it is no wonder that its distinct process has become the topic of much research in the neurobiological universe (Hupbach et al, 2007; Nader & Hardt, 2009).

Researchers at Johns Hopkins University have isolated proteins in the brain's "fear center." If the proteins are removed, fearful memories can be removed. Although research is still in the early stages, this work could lead to a drug or medical procedure that could eliminate the painful memories that lead to PTSD.

An important discovery is that Creb plays a key role of transcriptional activity in signaling synaptic