Navigation Links
Episodic memory


Episodic memory refers to the memory of events, times, places, associated emotions, and other conception-based knowledge in relation to an experience. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory. The counterpart to declarative, or explicit memory, is procedural memory, or implicit memory.[1]

Contents

The cognitive neuroscience of episodic memory

The formation of new episodic memories requires the medial temporal lobe, a structure that includes the hippocampus. Without the medial temporal lobe, one is able to form new procedural memories (such as playing the piano) but cannot remember the events during which they happened. See the hippocampus and memory.

The prefrontal cortex (and in particular the left hemisphere) is also involved in the formation of new episodic memories (also known as episodic encoding). Patients with damage to the prefrontal cortex can learn new information, but tend to do so in a disordered fashion. For example, they might show normal recognition of an object they had seen in the past, but fail to recollect when or where it had been viewed (Janowsky et al., 1989). Some researchers believe that the prefrontal cortex helps organize information for more efficient storage, drawing upon its role in executive function. Others believe that the prefrontal cortex underlies semantic strategies which enhance encoding, such as thinking about the meaning the study material or rehearsing it in working memory (Gabrieli et al., 1998).

The hippocampus's role in memory storage

Researchers do not agree about how long episodic memories are stored in the hippocampus. Some researchers believe that episodic memories always rely on the hippocampus. Others believe the hippocampus only stores episodic memories for a short time, after which the memories are consolidated to the neocortex. The latter view is strengthened by recent evidence that neurogenesis in the adult hippocampus may ease the removal of old memories and increase the efficiency of forming new memories (Deisseroth et al 2004).

The relationship of episodic memory to semantic memory

Episodic memory is thought of as being a "one-shot" learning mechanism. You only need one exposure to an episode to remember it. Semantic memory, on the other hand, can take into consideration multiple exposures to each referent - the semantic representation is updated on each exposure.

Episodic memory can be thought of as a "map" that ties together items in semantic memory. For example, semantic memory will tell you what a "dog" looks and sounds like. All episodic memories concerning your dog will reference this single semantic representation of "dog" and, likewise, all new experiences with your dog will modify your single semantic representation of your dog.

Some researchers believe that episodic memories are refined into semantic memories over time. In this process, most of the episodic information about a particular event is generalized and the context of the specific events is lost. One modification of this view is that episodic memories which are recalled often are remembered as a kind of monologue. If you tell and re-tell a story repeatedly, you may feel that you no longer remember the event, but that what you're recalling is a kind of pre-written story.

Others believe that you always remember episodic memories as episodic memories. Of course, episodic memories do inform semantic knowledge and episodic memories are reliant upon semantic knowledge. The point is that some people do not believe that all episodic memories will inevitably distill away into semantic memory.

Gender differences in episodic memory performance

According to Brain activation during episodic memory retrieval: sex differences, women tend to outperform men on episodic memory tasks.

Age differences in episodic memory performance

Activation of specific brain areas (mostly the hippocampus) seems to be different between young and older people upon episodic memory retrieval, as shown by Maguire and Frith 2003. Older people tend to activate both left and right hippocampus, while young people activate only the left one. For more information, see aging and memory.

Emotion and episodic memory

The relationship between emotion and memory is complex, but generally, emotion tends to increase the likelihood that an event will be remembered later and that it will be remembered vividly. Flashbulb memory is one example of this.

Episodic memory damage

  • One neurological feature of autism is the ability to form semantic, but not episodic, memories (Ben Shalom, 1993).
  • The label "Amnesia" is most often given to patients with deficits in episodic memory.
  • Alzheimer's Disease tends to damage the hippocampus before other brain areas. This means that AD patients are often classed as amnesiacs.
  • A rare type of shell-fish poisoning called "Amnesiac Shellfish Poisoning" or ASP quite effectively and irreversibly damages the hippocampus, rendering one amnesiac.
  • Korsakoff's syndrome is brought on by many years' worth of excessive drinking. The syndrome is not the result of the alcohol, per se; rather, it is caused by the malnutrition that occurs when someone gets a large amount of his calories from alcohol.

Episodic memory in animals

In 1997, there was little evidence for episodic memory outside of humans. This is probably due to the difficulty in testing for it in animals. To meet the criteria of episodic memory, as espoused by Tulving (1983), evidence of conscious recollection must be provided. But demonstrating episodic memory in the absence of language, and therefore in non-human animals, is impossible because there are no agreed non-linguistic behavioural indicators of conscious experience (Griffiths et al., 1999).

Clayton & Dickinson (1998) were the first to provide evidence that animals may possess episodic memory. They demonstrated that Florida scrub-jays (Aphelocoma coerulescens) remember where they cached different food types and discriminately recovered them, depending on the perishability of the item and the amount of time that elapsed since caching. Thus, scrub-jays appear to remember the ‘what-where-and-when’ of specific caching events in the past. Clayton & Dickinson (1998) argued that such performance met the behavioural criteria for episodic memory. However, because the study did not address the phenomenological aspects of episodic memory, the authors referred to this ability as “episodic-like” memory.

According to a study done by the University of Edinburgh in 2006 hummingbirds are the first animal to demonstrate two aspects of episodic memory - the ability to recall where certain flowers were located and how recently they were visited. Scientists tracked how often hummingbirds visited eight artificial flowers filled with a sucrose solution in the birds' feeding grounds. They refilled half the flowers at 10 minute intervals and the other half 20 minutes after they had been emptied. The birds' return to the flowers matched the refill schedules: flowers refilled at 10-minute intervals were visited sooner. "To our knowledge, this is the first demonstration that animals in the wild can remember both the locations of food sources and when they visited them," said Susan Healy, of the University of Edinburgh.

Other studies have now started to demonstrate this episodic-like memory in other animal species, which have brains more similar to humans. For example, Kart-Teke and colleagues have demonstrated rats' preference for items it sees which is dependent on what it saw, where it saw it and when it saw it (Kart-Teke et al, 2006). In addition, studies by Eacott and colleagues (Eacott et al, 2005) have shown rats can recall (remember without any cueing influences) what they saw and where depending on which past situation they are being asked to remember.

References

  • Deisseroth K., Singla S., Toda H., Monje M., Palmer T.D., Malenka R.C. (2004) Excitation-neurogenesis coupling in adult neural stem/progenitor cells. Neuron. 2004 May 27;42(4):535-52.
  • Tulving, E. (1972). Episodic and semantic memory. In E. Tulving & W. Donaldson (Eds.), Organization of memory, (pp. 381-403). New York: Academic Press.
  • Tulving, E. (1983). Elements of Episodic Memory. Oxford: Clarendon Press.
  • Tulving, E. (2002). Episodic Memory: From Mind to Brain. Annu. Rev. Psychol. 53:1-25.
  • Griffiths, D. P., Dickinson, A. & Clayton, N. S. (1999). Declarative and episodic memory: What can animals remember about their past? Trends in Cognitive Science, 3, 74–80.
  • Clayton, N. S. & Dickinson, A. (1998). Episodic-like memory during cache recovery by scrub-jays. Nature, 395, 272-274.
  • Kart-Teke, E., De Souza Silva, M.A., Huston, J.P. & Dere, E.(2006). Wistar rats show episodic-like memory for unique experiences. Neurobiology of Learning and Memory, 85, 173-182
  • Eacott, M.J., Easton, A. & Zinkivskay, A. (2005). Recollection in an episodic-like memory task in the rat. Learning & Memory, 12, 221-223

Notes

  1. ^ Tulving, E. (1984). Precis of Elements of Episodic Memory. Behavioural and Brain Sciences, 7, 223 – 268.

'"/>


(Date:10/20/2014)... 2014 Women’s health specialist, Dr. Amber ... Gynecology of Columbus, Inc., A Division of MaternOhio Clinical ... more than 100,000 patients annually. Dr. Murphy will provide ... stages of a women’s life. She is accepting new ... Westerville and Dublin. , Dr. Murphy offers a wide ...
(Date:10/20/2014)... Zereana Jess-Huff, a 34-year-old mother, corporate executive and ovarian cancer ... think outside the bra. She doesn’t try to hide her ... about women’s other lady parts. , "We have won the ... pink and everybody knows what you’re talking about,” Jess-Huff points ... not been won when it comes to gynecologic cancers. It ...
(Date:10/20/2014)... Principle Business Enterprises, a family owned ... top-of-the-line absorbent products. The company has recently made ... brand, Tranquility® Premium Protection absorbent products. The company ... its packaging a new look, and is currently working ... the public. , The new website, developed with Thread ...
(Date:10/20/2014)... October 20, 2014 Rockynol Retirement ... Center on Oct. 14. The $11 million project will ... and a cooked-to-order kitchen with full-service restaurant style dining. ... choice for first class Assisted Living apartments,” said Kara ... deserve the highest quality of care and this investment ...
(Date:10/20/2014)... National Teen Driver Safety Week is October 19-25, 2014 ... (Ohio AAP, http://www.ohioaap.org ) is joining the National Highway ... to talk to their teens and always set the rules ... the leading cause of death for U.S. teens. In 2012, ... 859 (42%) of those teen drivers were killed in crashes. ...
Breaking Medicine News(10 mins):Health News:OhioHealth Welcomes New Women’s Health Specialist to MaternOhio Specialists in Obstetrics & Gynecology of Columbus, Inc. 2Health News:OhioHealth Welcomes New Women’s Health Specialist to MaternOhio Specialists in Obstetrics & Gynecology of Columbus, Inc. 3Health News:Ovarian Cancer Survivor Mrs. Maryland Urges Media to Think Outside the Bra 2Health News:Ovarian Cancer Survivor Mrs. Maryland Urges Media to Think Outside the Bra 3Health News:Tranquility® Premium Protection Incontinence Products Releases New Logo and Website 2Health News:Rockynol Retirement Community Expands Assisted Living Center 2Health News:Ohio AAP Promotes National Teen Driver Safety Week 2
... Brands Donate $500,000 To Help Americans Live Heart-Healthy, ... North America Inc. today announced that it is ... heart health and encouraging healthy habits among Americans. ... the American Heart Association to address the dangers ...
... Office Expands with Appointment of New Strategic Talent -WEST ... strategic interactive marketing agency serving the healthcare industry, today ... the addition of four key new hires. Three of ... Group,s Manhattan offices which were established in 2007."We,re excited ...
... Practicing Clinicians Exchange (PCE) has formed a partnership ... to provide immunization continuing education programs to nurse practitioners ... In recognition of these vital healthcare providers, expanding role ... Updates throughout the year as part of the PCE ...
... generously during 2008 holiday shopping seasonFORT WORTH, Texas, Feb. ... its customers, raised nearly $1.5 million for the fifth-annual ... and fundraising initiative for St. Jude Children,s Research Hospital ... , Customers who shopped at RadioShack stores had ...
... Hospice By The Bay,s eight-week group provides teens, ages 13-17, who are ... to be with other young people who are grieving. , ... Larkspur, ... adults. Hospice By The Bay ,s eight-week group provides teens, ages ...
... Direct, Inc., a leading online retailer of contact lenses in the United ... from dry winter eyes can be easily prevented. , ... Bellevue, WA ... online retailer of contact lenses in the United States wants ...
Cached Medicine News:Health News:Leading Spring Water Brands From Nestle Waters Team Up With the American Heart Association START! Initiative 2Health News:Leading Spring Water Brands From Nestle Waters Team Up With the American Heart Association START! Initiative 3Health News:Cadient Group Continues Growth Trend with Key New Hires 2Health News:Practicing Clinicians Exchange Forms Partnership with CDC 2Health News:RadioShack Helps Raise $1.5 Million for St. Jude Children's Research Hospital(R) Fifth-Annual Thanks and Giving(R) Campaign 2Health News:RadioShack Helps Raise $1.5 Million for St. Jude Children's Research Hospital(R) Fifth-Annual Thanks and Giving(R) Campaign 3Health News:Hospice By The Bay Teen Grief Group Offers Support for Ages 13-17 2Health News:Contact Lens Wearers Should Blink More Often During Winter - Tips from VisionDirect.com to Keep Eyes Moist During Dry Winter Months 2Health News:Contact Lens Wearers Should Blink More Often During Winter - Tips from VisionDirect.com to Keep Eyes Moist During Dry Winter Months 3
Other medicine definitionOther Tags