Rare form of temporary amnesia highlights role of CA1 neurons in accessing memories

October 11, 2011 by Bob Yirka, Medical Xpress report

(Medical Xpress) -- German researchers working out of the Institute of Neuroradiology, University Hospital Schleswig-Holstein, University of Kiel, have found through the study of a rare form of temporary amnesia, that impairment of the CA1 neuron clusters in the Hippocampus appears to cause a loss of so-called autobiographical memories. The team has published its results in this week's issue of the Proceedings of the National Academy of Sciences.

Autobiographical memories are those that are built up over a lifetime and serve to provide a means of self identification and are thought to be a part of self-awareness. The loss of such memories tends to leave people with a limited ability to understand who they are which quite obviously makes understanding the world around them very difficult.

To find out what causes loss of autobiographical memories, the research team looked at patients afflicted with “acute transient global ” a rare but debilitating condition that results in almost a total loss of short term memory in conjunction with a variety of problems associated with long term memory. Such patients are also incapable of forming new memories. Because it is so rare and because it generally only lasts for two to eight hours it has been notoriously difficult to study and until now, the condition has been little understood.

Because the team was working out of a major hospital they were able to have patients with the condition undergo an MRI while still experiencing symptoms. In so doing, they found that of sixteen patients examined, fourteen exhibited lesions in the CA1 cell clusters. One of the researchers, Gunther Deuschl, notes that this indicates that proper functioning of the CA1 cells appears to be a necessary component in memory activation and retention.

This association could mean big news for the millions of people who suffer from dementia, particularly those with Alzheimer’s disease, as the in general and the CA1 in particular, appears to be one of the first to be affected in such people. By narrowing down which parts of the brain are impacted when memory loss occurs and how, new drugs might be developed that can target specific brain cells, thus helping to ward off nerve degeneration while minimizing side effects.

Explore further: Neuroscientists find cellular mechanism that shapes your memories

More information: CA1 neurons in the human hippocampus are critical for autobiographical memory, mental time travel, and autonoetic consciousness, PNAS, Published online before print October 10, 2011, doi:10.1073/pnas.1110266108

Autobiographical memories in our lives are critically dependent on temporal lobe structures. However, the contribution of CA1 neurons in the human hippocampus to the retrieval of episodic autobiographical memory remains elusive. In patients with a rare acute transient global amnesia, highly focal lesions confined to the CA1 field of the hippocampus can be detected on MRI. We studied the effect of these lesions on autobiographical memory using a detailed autobiographical interview including the remember/know procedure. In 14 of 16 patients, focal lesions in the CA1 sector of the hippocampal cornu ammonis were detected. Autobiographical memory was significantly affected over all time periods, including memory for remote periods. Impairment of episodic memory and autonoetic consciousness exhibited a strong temporal gradient extending 30 to 40 y into the past. These results highlight the distinct and critical role of human hippocampal CA1 neurons in autobiographical memory retrieval and for re-experiencing detailed episodic memories.

Related Stories

Neuroscientists find cellular mechanism that shapes your memories

September 12, 2011
(Medical Xpress) -- VU University Amsterdam neuroscientists discovered what happens in your nerve cells upon memory recall, as appeared in this week's advance online publication of Nature Neuroscience. This is important for ...

How do I remember that I know you know that I know?

August 24, 2011
(PhysOrg.com) -- “I’ll meet you at the place near the thing where we went that time,” says the character Aaron in the 1987 movie Broadcast News. He and the woman he’s talking to have a lot of common ground, ...

Recommended for you

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

Recording a thought's fleeting trip through the brain

January 17, 2018
University of California, Berkeley neuroscientists have tracked the progress of a thought through the brain, showing clearly how the prefrontal cortex at the front of the brain coordinates activity to help us act in response ...

Midbrain 'start neurons' control whether we walk or run

January 17, 2018
Locomotion comprises the most fundamental movements we perform. It is a complex sequence from initiating the first step, to stopping when we reach our goal. At the same time, locomotion is executed at different speeds to ...

Miles Davis is not Mozart: The brains of jazz and classical pianists work differently

January 16, 2018
Keith Jarret, world-famous jazz pianist, once answered in an interview when asked if he would ever be interested in doing a concert where he would play both jazz and classical music: "No, that's hilarious. [...] It's like ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.