THE BRAIN: GROW WITH IT … 2/3
A key to slowing decline may lie in not exercising the brain enough, nor the body also.
Aging: exercise, learning, and memory
There’s no escaping it: cognitive function declines with age. But it’s not all bad news. An important key to slowing decline may lie not only in exercising the brain but the body also.
An indication of aging is the gradual loss of memory. It becomes apparent that challenging ourselves at learning and memorizing goes a long way in maintaining a healthy mind well into old age. If you don’t use it, you lose it. It is like every muscle in the body.
QBI’s Professor Perry Bartlett was one of the first people to discover that the adult brain contains stem cells capable of making new neurons, a process called NEUROGENESIS. As the brain ages, these stem cells lose their ability to produce new neurons, causing cognitive function to decline.
Ground-breaking research by Prof Bartlett and Dr Daniel Blackmore recently identified that exercise is able to increase the production of new brain cells and improve learning and memory. They are now heading up a clinical trial monitoring 300 people aged 65 and older to identify the right amount, intensity and type of exercise that leads to cognitive improvement in the aging brain. “This will be the most comprehensive analysis yet of why exercise is beneficial,” Prof Bartlett explains. “Ultimately, we would hope to have clear public health guidelines as to how exercise can both prevent and reverse dementia.”
To study complex human behavior, such as remembering appropriate information at the right time, Howard Eichenbaum of Boston University, had to train rats to memorize an important piece of information and then find a way for them to use it. So, his team trained rats to find Froot Loops in flowerpots. “Rats are absolutely nuts about Froot Loops,” he says.
For example, the rats learned that in room A the cereal is hidden in a pot filled with purple plastic beads that smell sweet. But in room B, the goods are in the pot filled with black paper shreds that smell spicy. “Rats are great with odors and textures, so we’re using textural and olfactory cues to direct them to express their memory,” says Eichenbaum.
As the rats navigate from room to room, Eichenbaum’s team records their brain activity using electrodes inserted into the brain. They monitor both the HIPPOCAMPUS, known to be the seat of memory in the brain, and the PREFRONTAL CORTEX thought to be a coordinator.
This experiment confirmed that circuitry spans long distances in the brain and supports a complex dialog between two brain structures.
Memory, recollecting, and coordinating
This coordination is important because many things can go wrong to interrupt it. When Eichenbaum’s team temporarily disabled the PREFRONTAL CORTEX, the rats foraged in every pot, not because they don’t recognize the pots but because they don’t know which pot contains a reward based on the room they are in. “The prefrontal cortex has a very specific role,” says Eichenbaum. “It doesn’t activate the right memories, but rather it prevents the wrong memories from intruding.”
There is no direct anatomical connection in the brain between the PREFRONTAL CORTEX and DORSAL HIPPOCAMPUS, so it isn’t clear how messages are passed between them. But Eichenbaum’s studies suggest that there may be an indirect, bidirectional route that involves slow, pulsing brain rhythms called theta rhythms. These rhythms originate in deep structures in the middle of the brain, synchronized between the HIPPOCAMPUS and the PREFRONTAL CORTEX, that allow information to flow between them.
To explore this possibility, Eichenbaum is using Optogenetics, a powerful tool that allows researchers to configure specific neurons in the brains of rats so that they can be turned on or off using laser light. “We hope to trace the whole pathway of the circuit that is crucial to this dialog,” says Eichenbaum.
It still doesn’t explain what is actually happening when retrieving memories. Is it a matter of molecular transfer or is it electrical? When accessing a memory not thought about for 20 years or more, what exactly goes on in the brain? Do electrical transmissions happen along nerve pathways or is it biochemical? Or do our memories interact with some universal consciousness?
One would think that in this day and age we would know the exact biological mechanism for memory storage and retrieval. The fact that top scientists are still hypothesizing and guessing what is happening leads us to further research.
Just imagine if one day in the future, history mocks us for our belief that memory was stored in the brain. We have no proof that the brain has any processing power at all. For all we know the brain is simply a biological antenna that tunes into vibrations emitted by some universal consciousness.
Sammy RNAJ — sammy.rnaj.writer@gmail.com — WhatsApp +96170499352
