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Long-term memory (LTM) is memory that can last as little as 30 seconds or as long as decades. It differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 30 seconds. Biologically, short-term memory is a temporary potentiation of neural connections that can become long-term memory through the process of rehearsal and meaningful association. The proposed mechanism by which short-term memories move into LTM storage is via long-term potentiation, which leads to a physical change in the structure of neurons. Notably, the time scale involved at each level of memory processing remains under investigation.

As long-term memory is subject to fading in the natural forgetting process, several recalls/retrievals of memory may be needed for long-term memories to last for years, dependent also on the depth of processing. Individual retrievals can take place in increasing intervals in accordance with the principle of spaced repetition. This can happen quite naturally through reflection or deliberate recall, often dependent on the perceived importance of the material.

Contents 1 Sleep 2 Types of memory 3 Disorders of memory 3.1 Traumatic Brain Injury 3.2 Neurodegenerative Diseases 4 See also 5 References & bibliography 6 Key texts 6.1 Books 6.2 Papers 7 Additional material 7.1 Books 7.2 Papers 8 External links

[edit] Sleep

Some theories consider sleep to be an important factor in establishing well-organized long-term memories. (See also sleep and learning.)

According to the theory of Tarnow, long term memories are stored in dream format (reminiscent of the Penfield & Rasmussen’s findings that electrical excitations of cortex give rise to experiences similar to dreams). During waking life an executive function interprets long term memory consistent with reality checking. At this point in time, this is not considered a generally accepted theory.

[edit] Types of memory

The brain does not store memories in one unified structure, instead, different types of memory are stored in different regions of the brain. LTM is typically divided up into two major headings: declarative memory and procedural memory.

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1. Declarative memory refers to all memories that are consciously available. These are encoded by the hippocampus, entorhinal cortex, and perirhinal cortex, but consolidated and stored elsewhere in the cortex. The precise location of storage is unknown, but the temporal cortex has been proposed as a likely candidate. Declarative memory also has two major subdivisions:
   • Episodic memory refers to memory for specific events in time
   • Semantic memory refers to knowledge about the external world, such as the function of a pencil.
2. Procedural memory refers to the use of objects or movements of the body, such as how exactly to use a pencil or ride a bicycle. This type of memory is encoded and probably stored by the cerebellum and the striatum.
3. Emotional memory is the memory for events that evoke a particularly strong emotion. This is not entirely accepted within the scientific community as its own type of memory and may be ultimately classified as either declarative or procedural, but in many ways is a combination of the two. Emotional memories are consciously available, but elicit a powerful, unconscious physiological reaction. They also have a unique physiological pathway that involes strong connections from the amygdala into the prefrontal cortex, but much weaker connections running back from the prefrontal cortex to the amgydala.

[edit] Disorders of memory

Minor everyday slips and lapses of memory are fairly commonplace, and may increase naturally with age, when ill, or when under stress (Reason J.). Some women may experience more memory lapses following the onset of the menopause[1]. More serious problems with memory generally occur due to traumatic brain injury or neurodegenerative disease[2]:

[edit] Traumatic Brain Injury

The majority of findings about memory have been the result of studies that lesioned specific brain regions in rats or primates, but some of the most important work has been the result of accidental or inadvertant brain trauma. The most famous case in memory studies is the case study of HM, who had parts of his hippocampus, parahippocampal cortices, and surrounding tissue removed in an attempt to cure his epilepsy. His subsequent total anterograde and partial retrograde amnesia provided the first evidence for the localization of memory function, and further clarified the differences between declarative and procedural memory.

[edit] Neurodegenerative Diseases

Very many neurodegenerative diseases can cause memory loss. Some of the most prevalent (and consequently, most intensely researched) include Alzheimer's Disease, Dementia, Huntington's Disease, Multiple Sclerosis, and Parkinson's Disease. None act specifically on memory; instead memory loss is often a casualty of generalized neuronal deterioration. Currently, these illnesses are irreversible, but research into stem cells, psychopharmacology, and genetic engineering hold much promise.

[edit] See also

• Long-term potentiation
• Amnesia
• Implicit memory
• Contrast Short-term memory

[edit] References & bibliography

[edit] Key texts

[edit] Books

[edit] Papers

• Ahlberg. S. W and Sharps, M. J. (2002) Bartlett revisited: reconfiguration of long-term memory in young and older adults, The Journal of Genetic Psychology, 2002, 163(2), 211-18.
• Strand, B. 7. (19 75) Effects of instructions for category organization on long-term retention.Journal of Experimental Psychology: Human Learning & Memory 1(6). 780-6.
• Tarnow, E. (2003) How Dreams And Memory May Be Related. Neuro-Psychoanalysis 5(2), 177-182 and also http://cogprints.org/2068/
• Warrington, E.K. and Weiskrantz, L. (1973) An analysis of short term and long term memory defects in man. In: J.A. Deutsch (ed.) The Physiological Basis of Memory, New York: Academic Press.
• Williams, M.D. and Hollon, J.D. (1981) The process of retrieval from very long-tern memory, Cognitive Science 5: 87-119.

[edit] Additional material

[edit] Books

[edit] Papers

[edit] External links

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Memory
Types of memory
Auditory memory | Autobiographical memory | Collective memory | Early memories | Echoic Memory | Eidetic memory | Episodic memory | Explicit memory  |Exosomatic memory | False memory |Flashbulb memory | Iconic memory |Institutional memory | Long term memory | Procedural memory | Prospective memory |Repressed memory |Retrospective memory | Semantic memory |Sensory memory | Short term memory |Spatial memory | State-dependent memory | Verbal memory  | Visual memory  | Tonal memory | | Working memory  |
Aspects of memory
Childhood amnesia | Cryptomnesia |Cued recall | Eye-witness testimony | Memory and emotion | Forgetting |Forgetting curve | Free recall |Levels-of-processing effect |Memory consolidation |Memory decay | Memory distrust syndrome |Memory inhibition | Memory and smell | Memory loss | Memory optimization | Memory trace | Mnemonic | Memory biases  | Tip of the tongue |Lethologica | Priming | Proactive interference | Prompting | Recency effect | Reminiscence | Retroactive interference | Source amnesia |
Memory theory
Memory encoding | Baddeley | Memory-prediction framework | Memory consolidation | Forgetting | Recall | Recognition | Atkinson-Shiffrin | Interference theory | Memory-prediction framework | Dual-coding theory |Decay theory |
Mnemonics
Method of loci | Mnemonic room system | Mnemonic dominic system | Mnemonic link system |Mnemonic major system | Mnemonic peg system | [[]] | [[]] | [[]] |[[]] |
Neuroanatomy of memory
Amygdala | Hippocampus | prefrontal cortex  | Neurobiology of working memory | Neurophysiology of memory | Rhinal cortex | [[]] |[[]] |
Neurochemistry of memory
Glutamatergic system  | [[]] | [[]] |[[]] | [[]] | [[]] | [[]] | [[]] |[[]] |
Memory in clinical settings
Alcohol amnestic disorder | Amnesia | Memory disorders | False memory | Memory and aging | Traumatic memory | | Dissociative fugue |Hyperthymesia |Repressed memory |
Assessment of memory
Benton | MERMER | Rivermead | TOMM |Wechsler | MAS |Rey-15 | PDRT | CAMPROMPT | WMT |
Treating memory problems
CBT | Psychotherapy |EMDR |Recovered memory therapy |Reminiscence therapy |Memory clinic | Rewind technique |
Prominant workers in memory|-
Baddeley | Broadbent |Ebbinghaus  | Kandel |McGaugh | Schacter  | Treisman | Tulving  |
Philosophy and historical views of memory
Aristotle | [[]] |[[]] |[[]] |[[]] | [[]] | [[]] | [[]] |
Miscellaneous
Journals | Learning, Memory, and Cognition |Journal of Memory and Language |Memory |Memory and Cognition | [[]] | [[]] | [[]] |

This page uses content from the English-language version of Wikipedia. The original article was at Long-term memory. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.