Category: Memory

Why an odour can transport our minds so quickly, much more so than a sight, sound or touch.

The parts of the brain responsible for smell and memory have a unique connectivity with each other, a study finds.

The results help explain why a smell, like that of cut grass, can so powerfully evoke a long-forgotten memory.

Dr Christina Zelano, study co-author, said:

“…smells are a profound part of memory, and odors connect us to especially important memories in our lives, often connected to loved ones.

The smell of fresh chopped parsley may evoke a grandmother’s cooking, or a whiff of a cigar may evoke a grandfather’s presence.

Odors connect us to important memories that transport us back to the presence of those people.”

The hippocampus — the area of the brain vital for memory — has direct access to the olfactory areas of the brain (those related to smell).

Other primary senses like vision, hearing and touch do not show the same strong connection with memory, the researchers found.

Dr Christina Zelano, study co-author, said:

“During evolution, humans experienced a profound expansion of the neocortex that re-organized access to memory networks.

Vision, hearing and touch all re-routed in the brain as the neocortex expanded, connecting with the hippocampus through an intermediary–association cortex–rather than directly.

Our data suggests olfaction did not undergo this re-routing, and instead retained direct access to the hippocampus.”

The study of brain scans and electrodes placed on the brain also found that the connectivity between memory and smell areas of the brain changes as people breathe in and out through their nose.

Dr Zelano said:

“This has been an enduring mystery of human experience.

Nearly everyone has been transported by a whiff of an odor to another time and place, an experience that sights or sounds rarely evoke.

Yet, we haven’t known why.

The study found the olfactory parts of the brain connect more strongly to the memory parts than other senses.

This is a major piece of the puzzle, a striking finding in humans.”

Loss of the sense of smell has become more of a focus as it is a  common symptom of COVID.

Dr Zelano said:

“Most people who lose their smell to COVID regain it, but the time frame varies widely, and some have had what appears to be permanent loss.

Loss of the sense of smell is underestimated in its impact.

It has profound negative effects of quality of life, and many people underestimate that until they experience it.

Smell loss is highly correlated with depression and poor quality of life.”

The study was published in the journal Progress in Neurobiology (Zhou et al., 2021).

With age, people’s gut becomes less healthy and this is linked to memory problems and Alzheimer’s.

Garlic could help prevent age-related memory problems by improving gut health, research suggests.

Typically, with age, people’s gut becomes less healthy and this is linked to memory problems and Alzheimer’s.

However, a compound in garlic called allyl sulfide may help support the healthy bacteria in the gut.

It restored both long- and short-term memory in the study of aging rodents.

Dr Jyotirmaya Behera, the study’s first author, said:

“Our findings suggest that dietary administration of garlic containing allyl sulfide could help maintain healthy gut microorganisms and improve cognitive health in the elderly.”

Recent research has shown that gut health affects brain health.

Dr Neetu Tyagi, study co-author, said:

“The diversity of the gut microbiota is diminished in elderly people, a life stage when neurodegenerative diseases such as Alzheimer’s and Parkinson’s develop and memory and cognitive abilities can decline.

We want to better understand how changes in the gut microbiota relate to aging-associated cognitive decline.”

The study included mice who were two-years-old, which is the mouse-equivalent of people in their 60s.

Some were fed the allyl sulfide supplement and others not.

The results showed that the garlic constituent helped restore the cognitive abilities of the senior mice.

Both their long- and short-term memory was restored by the supplement.

It is possible that garlic could be used as a treatment for memory problems linked to aging.

The study was presented at the American Physiological Society’s annual meeting  (Behera et al., 2019).

Time does strange things to your memories.

People’s memories literally fade in vibrancy over time, research finds.

Colours get less vivid, sounds quieter and lights dimmer.

In fact, memory is something like an old printed photograph fading away over the years.

Even emotionally vivid moments — whether positive or negative — still tend to fade away.

Despite this, people generally still remember the gist of memories.

Dr Rose Cooper, the study’s first author, said:

“We found that memories seem to literally fade: people consistently remembered visual scenes as being less vibrant than they were originally experienced.

We had expected that memories would get less accurate after a delay, but we did not expect that there would be this qualitative shift in the way that they were remembered.”

For the study people were shown images that varied in colour saturation and brightness.

When they remembered these photos later on, their memories were consistently less bright and colourful than the originals.

People were more likely to remember negative pictures, but these negative memories had still faded in just the same way.

Dr Cooper said:

“We were also surprised to find that emotional memories did not influence the amount of fading, only the likelihood with which people remembered the images at all.”

Professor Elizabeth Kensinger, study co-author, likened this memory fade out effect to an Instagram filter:

“A simple analogy is what happens when you post a photo on Instagram.

You’re cued to apply a filter that changes the brightness or color saturation of the image.

In our study, we asked if forgetting is like applying a filter to past experience, and whether or not the emotional significance of the event would change which filter you apply.”

The study was published in the journal Psychological Science (Cooper et al., 2019).

Researchers measured the brain activity of students while they were typing and while using a keyboard.

People learn more and remember better when writing by hand, research finds.

Multiple studies find that compared with using a keyboard, handwriting makes a more powerful impression on the mind.

Professor Audrey van der Meer, study co-author, said:

“When you write your shopping list or lecture notes by hand, you simply remember the content better afterwards.”

Despite this, handwriting is now being superceded by digital skills in many schools around the world.

Some schools in Norway and many in Finland no longer teach handwriting at all.

Others are likely to follow this trend.

Professor van der Meer said:

“Given the development of the last several years, we risk having one or more generations lose the ability to write by hand. Our research and that of others show that this would be a very unfortunate consequence.”

For the research, Professor van der Meer and colleagues measured the brain activity of students while they were typing and while using a keyboard.

The results clearly showed the brain is more active while writing by hand:

“The use of pen and paper gives the brain more ‘hooks’ to hang your memories on.

Writing by hand creates much more activity in the sensorimotor parts of the brain.

A lot of senses are activated by pressing the pen on paper, seeing the letters you write and hearing the sound you make while writing.

These sense experiences create contact between different parts of the brain and open the brain up for learning. We both learn better and remember better.”

Research from others labs has shown that people remember more when writing by hand than they do when using a keyboard.

Writing by hand also boosts people’s ability to absorb concepts over the long-term.

In other words, people understand more when they take notes by hand.

Professor van der Meer believes learning to write by hand is important:

“Learning to write by hand is a bit slower process, but it’s important for children to go through the tiring phase of learning to write by hand.

The intricate hand movements and the shaping of letters are beneficial in several ways.

If you use a keyboard, you use the same movement for each letter.

Writing by hand requires control of your fine motor skills and senses.

It’s important to put the brain in a learning state as often as possible.

I would use a keyboard to write an essay, but I’d take notes by hand during a lecture.”

Learning to write by hand is beneficial for the brain’s development, says Professor van der Meer:

“The brain has evolved over thousands of years.

It has evolved to be able to take action and navigate appropriate behavior.

In order for the brain to develop in the best possible way, we need to use it for what it’s best at.

We need to live an authentic life.

We have to use all our senses, be outside, experience all kinds of weather and meet other people.

If we don’t challenge our brain, it can’t reach its full potential.

And that can impact school performance,”

The study was published in the journal Frontiers in Psychology (Askvik et al., 2020).