Explicit Memory Storage in Mammals also requires a Prion-like Protein
Is a functional prion also important for the persistence of memory in mammals? In mouse and in human there are four distinct CPEB genes; CPEB-1 to CPEB-4. Only the contribution of the N-terminal domain of CPEB3 has so far been functionally interrogated at the molecular and behavioral level. As a first step, we expressed CPEB3 in yeast and found that it displayed the two essential features of a prion-like protein: 1) it forms amyloidogenic aggregates and 2) aggregates are heritable across cell division.
Impairments of memory caused by protein synthesis inhibitors (PSI) have served as a basis to posit that memory storage, resulting from consolidation () and reconsolidation () processes, critically depends on the synthesis of new proteins in specific brain areas. However, amnesia caused by PSI can be rescued by a variety of hormonal and behavioral manipulations, as discussed in several topical reviews (; ; ). These findings questioned the stand that new protein synthesis is fundamental to memory formation and stimulated alternative ideas on the possible PSI actions. One of them, recently proposed by , suggests that PSI might predominantly exert amnestic effects by introducing meaningless “neuronal noise” to memories. Given the plentiful molecular effects exerted by PSI in different cell systems (), this possibility seems likely. Nevertheless, actions other than PSI-induced translational arrest have remained largely unexplored in experimental approaches and theoretical interpretations of PSI actions on neuronal function.
Protein Synthesis and Memory - ScienceDirect
Davis, H. & Squire, L. (1984). Protein synthesis and memory: a review. Psychological Bulletin 96(30), 518-559. American Psychological Association.
Dendritic Protein Synthesis, Synaptic Plasticity, and Memory
a. Types of memory. Tulving (1982) suggests that the priming effects (response to direct or indirect stimuli) were related to semantic memory and were independent of episodic memory. He submitted the subjects to different tests and he found that recognition decreased over a seven-day interval, while fragment completion was almost completely unaffected. Word recognition was easier when it followed word-fragment completion (study tool). Tulving (1989), seeing memory as the storing and retrieval of information, tried to demonstrate that there are two types of retrieval: episodic information (remembering/recollecting the past) and semantic information (knowing/ recalling the past). Episodic memory is related to personal experiences while semantic is related to factual knowledge of information. Episodic is dependent on semantic memory while semantic may be independent of the episodic memory. He provides evidence through amnesia and blood-flow studies. Episodic memory seems to occur in the frontal lobes. Semantic memory appears to be disbursed throughout the entire brain. Squire (1986) says that memory is stored in the region of the brain where the learning took place. Visual memories are stored in the visual processing regions of the brain. Thus, memory is localized. Procedural knowledge is the information acquired through skills or procedures. For instance, amnesiacs sometimes know how to do something without remembering having ever done it before. Declarative knowledge is information based on specific facts or data. It is related to episodic and semantic memory systems. Tulving and Schacter (1990) identify 4 types of memory systems: procedural (skill), semantic (knowledge), and episodic (experience) priming (perception). Priming is concerned with identification; it is a non-conscious system. b. Encoding and retrieval. Bower (1980) says that memorization of a set of items depends upon the manner in which the items are presented to the subject. Items presented with an organized presentation have superior recall to those presented randomly. Therefore, the manner in which learning materials are organized and the time of presentation has an impact on subjects' performance of recalling. There is an index of memory that operated in terms of word discrimination. Chaffin and Herrmann (1983) affirm that depth of processing is what maintains LTM, or the amount of elaboration an item undergoes while being processed, not only repetition aids, LTM. Interference produces poor recall. Mayer and Bower (1986) proved that mood and atmosphere are contextual cues that aid recall. Memorable stimuli can cause a given mood. Specific items may heighten mood associations. c. Memory in children Fivush and Hamond (1989) believed that event memory is an important form of memory. By trying to prove that they found that events, while unusual, are not particularly memorable although the children recalled more actions than objects. Hudson and Fivush (1983) say that generally, young children organize information schematically, rather than categorically. This schema is a spatially-temporally organization of expected results of real world situations. Children recalled stories better than word lists. Fivush and others (1984) stated that the event schema of real world situations is semantically organized. Children reported their own experience at a museum four times consistently over time and at the same order although there was a decrease in the number of facts recalled and the level of concreteness. In another experiment, Fivush (1984) examined the knowledge of a routine event (the description of a school day). He defines script as the schematically organized knowledge of an event. Children described a specific event (what did you do yesterday?), a specific activity (What book was read yesterday?), and general event (what happens in school?). The structure and content did not alter with time but some details are lost when retelling an event. d. Memory and aging Crook (1980) found that young groups outperformed aged groups on recalling longer digit numbers. Poon and Fozard (1980) found that all age groups recognize new words and that word frequency exerts a strong influence on recognition in LTM for all age groups. Camp and others (1983) found that there is no significance in the imagability level of an item and a change in strategy use. Subjects that use deep level processing can recall better. Mental imagery is related to personal experiences. High imagability items are recalled the easiest in deep level processing. Cutrona, M. P. (1975). A psycho educational interpretation of the Wechsler Intelligence scale for children - revised. Belleville, NJ: Cutronics Educational Publications.
Abel2008The role of protein synthesis in memory …
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