First, the Nobel committee awarded its prize for medicine to John O’Keefe, May-Britt and Edvard Moser (the latter two are married, an unusual occurrence in the awards) for their work on the hippocampus and entorhinal cortex showing that these structures map the animal’s environment and then maintain the memory to act as a GPS in the brain. O’Keefe’s initial work was in the early 1970s; he and the Moser’s have extended it over the years. Evidently O’Keefe has also demonstrated that this processing is temporally encoded relative to theta rhythms (see another post awhile back). With this award the Nobel committee acknowledges the beginning of a marvelous path of research and knowledge and recognizes that this basic science now contributes to the understanding of Alzheimer’s. Well done everyone.
I have posted about the hippocampus several times before. Here it is in the lower middle of the cerebral hemispheres, sidled up to the medial left temporal lobe.
In rats the hippocampus keeps track of the animal’s location and recognizes old places and presumably encodes new ones. Then the hippocampus communicates back and forth with the entorhinal cortex of the temporal lobe which processes where the animal is, where it is going or even intends to go. Lovely. Here it is as the yellow areas, 28 and 34.
Now the glory of this comes in the temporal handling of information, maintaining data for the recognition of the old and familiar and for the recall of old to guide new activity. While for rats this means spatial awareness (ah, maze running) and finding food and returning to the nest, for other animals the situation being processed comprises more complex elements until you get to humans and it supports our autobiographical experiencing among other things. Way cool.
The second news item is that a study showed that people who had lost their sense of smell were significantly more likely to die within the next five years, a correlation and not causation, as we are wont to say, but I had a curious association here. In my youth the orthodox view was that we were born with all the neurons we would ever have, and then later, they discovered that animals have new neurons develop all along the life span and the first place this was found was in the olfactory bulb (and yes, it does communicate both ways with the hippocampus) at the bottom of the brain. Here it is.
Hard to believe it helps us detect over a million different scents and recognize some of them (ah, the hippocampal functioning again). If someone has lost their sense of smell, the neurons here must have stopped regenerating; maybe that is a sign of a deeper lessening of the regeneration needed to sustain our life. Just wondering.
The last news story is from a 60 Minutes piece this past Sunday. I only caught the last few minutes. It was interesting and I have some quibbles about the translation into popular lingo. Researchers (especially Brian Hare at Duke) have found out that dogs do a lot more thinking than some give them credit for. They know to go where the human points to find the goody, a task that apes are not good at. Dr. Hare has developed intelligence tests for dogs that you can try at Dognition. Most interesting is that he has done functional MRIs with dogs. To do this they have to remain very still within the MRI machine and that in itself is some kind of good training. The bit I saw showed that when a Q-tip with a human scent is presented, the dog’s olfactory bulb lights up with activity. If that scent is the owner’s, the caudate nucleus lights up as well, and Dr. Hare construes this as a reflection of the warm feeling the dog has for its owner because the caudate is one of the brain’s pleasure centers. Lovely research really but here is the caudate and then my quibble.
I guess Hare refers to the caudate nucleus as a pleasure center because the dopaminergic system runs strongly there and dopamine is integral to rewards, but the caudate is part of the basal ganglia which plays a large role in voluntary movement with lesser known roles in cognitive and emotional activities, even, some say, the response to beauty and affection. So yes, that is or can be pleasurable but to discuss pleasure as a simple unitary concept is over-simplifying, and yes, I know he needs to be brief for TV but really. This clouds other issues and complexities. Perhaps smelling the owner engenders an orienting response and the basal ganglia would be involved in that. Perhaps, as another researcher pointed out, when dogs and owners interact, both produce oxytocin, an affection engendering hormone, and the basal ganglia could be involved in that. One thing I found amazing is that the dogs were able to inhibit movement despite clear activation of the motor system. Finally, part of Dr. Hare’s discussion with Anderson Cooper was about the possibility that the dog’s display of affection was only instrumental to get food, that as Mr. Cooper put it, his dog was only conning him. Now that is a whole other topic with another Dr. Hare, Robert Hare, author of the Psychopathy Checklist, and I see no reason to go there in our understanding of man’s best friend.
So there it is, 3 semi-related news reports from later Sunday, a good day really.