'Have I been here before?'

June 7, 2007
Dentate gyrus pattern
Dentate gyrus pattern. Photo by Matt Jones

"Have I been here before?" In today's fast-moving world of look-alike hotel rooms and comparable corridors, it can take a bit of thinking to answer this simple question. University of Bristol neuroscientists working with colleagues at the Massachusetts Institute of Technology (MIT) report in the June 7 early online edition of Science that they have identified a neuronal mechanism that our brains may use to rapidly distinguish similar, yet distinct places.

The work could lead to treatments for memory-related disorders, as well as for the confusion and disorientation that plague elderly individuals who have trouble distinguishing between separate but similar places and experiences.

Forming memories of places and contexts in which episodes occur engages a part of the brain called the hippocampus. The laboratory of Nobel Laureate, Susumu Tonegawa, Picower Professor of Biology and Neuroscience at MIT, has been exploring how each of the three hippocampal subregions-the dentate gyrus, CA1 and CA3-contribute uniquely to different aspects of learning and memory. In the current study, co-authors Matthew Jones, Research Councils UK (RCUK) Academic Fellow in the Department of Physiology at the University of Bristol and Dr Thomas McHugh, a Picower Institute research scientist, have revealed that the learning in the dentate gyrus is crucial in rapidly recognizing and amplifying the small differences that make each place unique.

Dr Jones, commenting on the paper, said: "We constantly make split-second decisions about how best to behave at a given place and time. To achieve this, our nervous system must employ highly efficient ways of rapidly recognising and learning important changes in our environment.

"This paper demonstrates that a particular protein signalling molecule (the NMDA receptor) in a particular network of brain neurons (the dentate granule cells of the hippocampus) is essential for these rapid discrimination processes, hopefully paving the way for therapies targeting learning and behavioural disorders."

Professor Tonegawa, a frequent world traveler, describing his own occasional experience of finding the airport in a new city uncannily familiar, added: "This occurs because of the similarity of the modules-gates, chairs, ticket counters-that define the context of an airport. It is only by seeking out unique cues that the specific airport can be identified."

Researchers believe that a set of neurons called 'place cells' fire to provide a sort of blueprint for any new space we encounter. The next time we see the space, those same neurons fire. Thus we know when we've been somewhere before and don't have to relearn our way around familiar turf. But similar spaces may activate overlapping neuronal blueprints, leaving room for confusion if the neurons are not fine-tuned.

In this study, the researchers used a line of genetically altered mice to pinpoint how the dentate gyrus contributes to the kind of pattern separation involved in identifying new and old spaces. Whilst the mice behaved normally in most situations, they became confused when required to discriminate between different spaces. This may model the difficulties in forming distinct memories for similar but distinct places and experiences that afflicts some elderly individuals.

In addition to Dr Matthew Jones, Professor Susumu Tonegawa and Dr Thomas McHugh, authors include Matthew Wilson, Picower Scholar and Professor; and colleagues from the University of California at Los Angeles and Beth Israel Deaconess Medical Center in Boston.

Source: University of Bristol

Explore further: Study shows gene's role in developing and maintaining cells key for a lifetime of memories

Related Stories

Aerobic exercise grows brain cells

January 20, 2010

(PhysOrg.com) -- Aerobic exercises such as running or jogging have long been known to be good for the health, but now new research, published in the Proceedings of the National Academy of Sciences (PNAS) has shown that it ...

A genetic basis for schizophrenia

July 21, 2009

Schizophrenia is a severely debilitating psychiatric disease that is thought to have its roots in the development of the nervous system; however, major breakthroughs linking its genetics to diagnosis, prognosis and treatment ...

Newborn brain cells 'time-stamp' memories

January 28, 2009

"Remember when...?" is how many a wistful trip down memory lane begins. But just how the brain keeps tabs on what happened and when is still a matter of speculation. A computational model developed by scientists at the Salk ...

Safety Can be Learned - and Helps Combat Depression

December 15, 2008

(PhysOrg.com) -- Learning a feeling of safety activates cellular and molecular processes that act against depression. This has been analysed using a new animal model that helps examine and explain the relevant cell biology ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

(PhysOrg.com) -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...

0 comments

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.