Friday, 17 October 2014

"Place cells" discovered in the rat brain

John O'Keefe
Image: Nobelprize.org

This month John O'Keefe, May-Britt Moser and Edvard Moser were awarded the Nobel Prize in Physiology or Medicine for their work identifying the brain's "GPS system" - the internal maps that allow us to understand our position in space. The Moser's discovery of grid cells this century built upon O'Keefe's earlier accomplishment at UCL in London, the discovery of place cells in the brain. Here, we look back to his 1971 "Short Communication" in the journal Brain Research which presented his preliminary evidence for place cells in rats.

Earlier research had suggested that damage to a rat's hippocampus (a bilateral brain structure in the temporal lobes) causes it to become confused when attempting spatial tasks. O'Keefe wanted to look in detail at what different hippocampal regions were up to when a rat moves around, specifically to see whether there was a neural system "which provides the animal with a cognitive, or spatial, map of its environment".

Together with student Jonathan Dostrovsky, O'Keefe inserted microelectrodes through the skulls of 23 rats, each arriving at a slightly different position in the hippocampus. Each rat could then explore its limited environment - a 24cm by 36cm platform - while the experimenters recorded neural activity from the electrodes.

In all, the study took recordings from 76 different positions in the hippocampus. Some turned out to fire in response to particular behaviours, such as walking, eating, or grooming; some while the rat was aware of something; some during sleep; some for no detectable reason at all. But electrodes at eight locations only gave their full response "when the rat was situated in a particular part of the testing platform facing in a particular direction" (italics in original). This was the first ever discovery that different brain cells represent unique location and orientation information.

O'Keefe and Dostrovsky attempted to find straightforward explanations for this spatial sensitivity. But eliminating sound cues (by silencing fans and other unmoving sound sources) and olfactory ones (by rotating the testing platform) had no effect on the neural activity of these eight “place cells*”. This solidified the possibility that the eight weren't responding to information arriving through the senses from "out there", but from a representation of space that existed within the brain.

Our findings "suggest that the hippocampus provides the rest of the brain with a spatial reference map," concluded O'Keefe and Dostrovsky. As explained by Hugo Spiers in next month’s Psychologist magazine, this evidence opened up investigations into spatial memory and cognition, which began to demand some kind of coordinate system feeding into the place cells themselves. That idea was finally cashed out by the Mosers, who established that the entorhinal cortex, a key interface between the hippocampus and the neocortex, contains grid cells that perform this function by encoding atop space grids of hexagons in a honeycomb fashion familiar to anyone who has played too many wargames.

A systematic investigation into the through-lines between neural activity, cognition and behaviour, the body of work by O’Keefe and the Mosers is groundbreaking, genuinely surprising, and provides fertile ground for continued exploration, not only of rats, but of ourselves: minds within bodies within space.
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  ResearchBlogging.orgO'Keefe, J., & Dostrovsky, J. (1971). The hippocampus as a spatial map. Preliminary evidence from unit activity in the freely-moving rat Brain Research, 34 (1), 171-175 DOI: 10.1016/0006-8993(71)90358-1

*note the term "place cell" was not used in this paper.

Post written by Alex Fradera (@alexfradera) for the BPS Research Digest.

7 comments:

Research Digest said...

If they were just told that they were going to teach it, without having to put together teaching notes/PowerPoint etc., it could be the case that simple level of motivation could also play a role(?) One would expect that actually having to teach something to a group has larger effects again, although in terms of why this happens it could be difficult to disentangle the effects of (a). processing the information in greater depth and having to arrange it in a coherent structure from (b). the greater amount of simple rehearsal of the material, particularly if teaching takes the form of an oral presentation with limited cues for the teacher.


At an applied level, it may not be practical for everyone to teach during the lecture/class, but one could ask/encourage students to teach the material or some aspect of it to one of their peers-even just someone in the class who is struggling with the same material.

http://andrewspsychologyarchive.blogspot.ie/

Research Digest said...

If zombies, who are not very well known for their keen sense of survival, are trying to exit the room through door A and not door B, then leaving through door B, where Creature X, of which the zombies are scared, might be sitting, sounds like a very good plan for ending your life prematurely and permanently.

Research Digest said...

I find this article
titled, “Student learn better when they think they’re going to have to teach
the material” to be very intriguing as I am a student myself and can relate to
the group being study. During the study, two groups of undergrad students were
given the same passage to study, but only one group was told they would be
teaching the material afterwards. The results showed that overall the group
that was told they would be teaching the material preformed better during
testing. I know that when I am supposed to teach others about something or
share out during class, I am sure to know my information well and thoroughly. Just
knowing that I will be sharing information in front of others or another encourages
me to study harder and practice recall. I believe this method of having
students know they are teaching or have the possibility of teaching on a topic
would greatly benefit them. The student will most likely study and retain more
information as they organize ideas and think about what concepts are of greater
importance; therefore, he or she will most likely perform better on tests and
in the classroom overall.

Research Digest said...

I think different groups of students should undergo the same experiment as this one..only with different subject material that they think they might have to teach. It would further support the hypothesis that thinking they would have to teach another would help them retain information. Letting the students take notes might also prove relevant in further studies.


Also, to further the experiment, both groups would be told they would have to teach the material being read. With only one group actually having to do so. I, for one, am curious to see how the students would react. And, if that study proved fruitful, it could possibly lead to another form of teaching students in the future.

Research Digest said...

Great stuff! Talking about students, and you will be surprised when you get to know what they do at www.reliablepapers.com.

Research Digest said...

Definitely there are different approaches or ways how
students learn and memorize the material. First of all what kind expectations
from others a student has. To know that you will be tested only, the main goal
is to get familiar with material and “scan” as much information as student
can. Since studying time is limited the
main concentration goes only on memorizing material which sometimes can be hard
because you are in a rush. Knowing that you will not going to be asked to talk
and teach does not require to understand the main points of the material. There
is expectations that student will find “key” words on a test, so he/she expect
to do well. There on a different level to learn something and be ready to teach
it requires different method of learning.
Additional need like “to be able to present information verbally ”come
across, and that’s make a huge different
how a student learns material. There is higher expectation to perform
well. Student becomes more aware in recognizing and putting together the main
points. Instead of just “scanning material” a student has to put logic into and
try to understand the importance of material. There is a need to understand the
material in order to be able to present it; not only to memorize it. Each
student has different ways of learning and there seems to be a gap between
trying to learn/ memorize information and being able to really understand the
material. But it is true that the way how a student will have to present information
play a big role of how that student will try to learn that material.

Research Digest said...

This study successful demonstrates the importance of learning and how it affects memory. As stated in the study, the students who are told they will be teaching the material to others take a more organized approach to learning the material and are able to establish an order of importance as well as filter out unnecessary information. Whereas the students who are told they are going to be tested try to memorize as much information as possible, especially since they are restricted to 10 minutes of study.
Another factor that could also influence the outcome of this study is test anxiety. The students that are told they are going to be tested on the material might expect their results to be lower since they have so little time to prepare, and therefore the results can be skewed. They feel less in control, whereas the other students who have to teach the material are in control of the material and therefore are factors in instructing their peers. There is less pressure.

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