Last week I talked about a new invention that can smell trace volatile biomarkers on a person’s breath and give diagnoses as to whether that person already has one or more of 17 common life threatening diseases.
I realized that we sometimes experience vivid emotional memories because our olfactory sense, smelling, is directly linked to two parts of our brain, the amygdala and the hippocampus.
Sometime ago, I walked into a department store somewhere in Tennessee. The store had wooden floors that were a little musty smelling. I was immediately transported back in time to a store on Beaver Island (located in the middle of Lake Michigan), a store I was entranced by when I was but five years old.
More recently (a few summers ago), it started to drizzle after a long dry spell. I thought ‘What is that smell, the smell of rain as it commences, and why don’t I smell it every time it rains?”
The answer is petrichor, a mixture of the organic and inorganic, that is created during dry spells, and becomes airborne when “resuscitated” by the first few drops of rain. Learn all about it clicking the video above.
So much exciting work is going on in Alzheimer’s disease research, it’s hard to keep up.
In a previous post, I wrote about research being done on a group of people in Columbia (Yarumalians) that suffered tremendously from genetically induced early onset Alzheimer’s disease and how the National Institute of Health and Roche were working on an drug therapy to inhibit the formation of beta amyloid peptides that show up in Alzheimer’s disease.
But what do you do if you already have beta amyloid peptides in your brain and are showing symptoms of Alzheimer’s disease? It is too late? Can you stop further formation of beta amyloid peptides, or even get rid of them, and can you therapeutically restore cognitive function in folks who have already lost memory and motor functions?
Enter Dr. Li-Huei Tsai of the Picower Institute for Learning and memory at MIT. In a tour de force of research that goes beyond brilliant, she and her team at MIT asked a different question than normally asked in Alzheimer’s research.
It is known that the onset of Alzheimer’s disease is marked by a corresponding decline in a certain “brain clock” pulsing called gamma rhythm. This rhythm runs between about 30 and 120 Hz, and is needed to perform complex motor functions like speaking. Dr. Tsai asked “What if we forget about attacking the formation of beta amyloid peptides, and just restore the gamma rhythm?”
Her team did just that first by taking mice with early Alzheimer’s disease and drilling tiny holes in their heads so as to shine light via fiber optics on the proper mice brain cells at an ideal frequency of 40 Hz. (The technique is called optogenetics.)
To her team’s utter surprise, and after only one hour of gamma rhythm stimulation, the microglia (or brain immune cells that act as garbage collectors in the brain) had increased dramatically in size, indicating that they had been “turned back on”, and were aggressively scavenging up beta amyloid peptides. She was able to show that the microglia had removed roughly 50% of the pre-existing beta amyloid peptides.
Of course, drilling holes in people’s heads is an unappealing therapy, so her team further investigated whether just shining white LED light at 40 Hz into the eyes of the same kind of mice would produce the same reduction in pre-existing beta amyloid peptides. Much to her team’s surprise, it did, although the therapy required more light treatment sessions that the “direct to brain therapy” previously done.
Considering that Alzheimer’s disease kills more people than cancer or heart disease, this research is most welcome.
To learn more about Dr. Tsai’s work, check out this recent Radiolab episode.
Retrieving Memories Lost to Alzheimer’s Disease
Regarding the question of whether memories “lost” due to Alzheimer’s are truly gone forever, or just not retrievable, Nobel Laureate Dr. Susumu Tonegawa, also of MIT, has shown that memories associated with an electrical shock and lost due to early onset Alzheimer’s disease can be restored with the same optogenetic gamma rhythm treatment used by Dr. Tsai.
Good and Bad Memories
While we certainly don’t want to lose real memories needed to function in the real world, we also don’t want false memories, hallucinations of events and images that don’t correspond to the real world.
In the above Ted Talk, noted neurologist Dr. Oliver Sacks talks about hallucinations that visually impaired individuals experience, and why certain images prevail in these hallucinations.