Why we don’t remember details of our past

A colleague once suggested that I must have had major trauma as a child.  She thought I’d repressed something horrible because I remember very little of my childhood.  Try as I might the only “trauma” I could dredge up was the day my brother came home from the hospital.  I had just spent my entire life being an only child, the center of attention, and was not happy about the possibility of being dethroned.  I vaguely remember trying to drop him in the toilet.

Researchers from the University of Toronto, Canada, have discovered a reason why we often struggle to remember the smaller details of past experiences – how the brain encodes useful memories while losing the irrelevant and minor details over time.

The Research distilled:

The research team found that there are specific groups of neurons in the medial prefrontal cortex (mPFC) of a rat’s brain – the region most associated with long-term memory. These neurons develop codes to help store relevant, general information from multiple experiences while, over time, losing the more irrelevant, minor details unique to each experience. 

“Memories of recent experiences are rich in incidental detail but, with time, the brain is thought to extract important information that is common across various past experiences,”

“Rats were given two experiences with an interval between each: one involving a light and tone stimulus, and the other involving a physical stimulus. This gave them two memories that shared a common stimulus relationship. The scientists then tracked the neuron activity in the animals’ brains from the first day of learning to four weeks following their experiences.“This experiment revealed that groups of neurons in the mPFC initially encode both the unique and shared features of the stimuli in a similar way,” says first author Mark Morrissey. “However, over the course of a month, the coding becomes more sensitive to the shared features and less sensitive to the unique features, which become lost.”

Image shows the location of the mPFC in the brain.

NeuroscienceNews.com image is for illustrative purposes only.

“On the contrary, we show that groups of neurons develop coding to store shared information from different experiences while, seemingly independently, losing selectivity for irrelevant details.”

I’m relieved to know that my brain does regular house-keeping to keep irrelevant details, like trying to do in my brother, from cluttering up my medial prefrontal cortex.  

I wonder if my brother remembers?

(jw)

 

 


Abstract

Generalizable knowledge outweighs incidental details in prefrontal ensemble code over time

Memories for recent experiences are rich in incidental detail, but with time the brain is thought to extract latent rules and structures common across past experiences. We show that over weeks following the acquisition of two distinct associative memories, neuron firing in the rat prelimbic prefrontal cortex (mPFC) became less selective for perceptual features unique to each association and, with an apparently different time-course, became more selective for common relational features. We further found that during exposure to a novel experimental context, memory expression and neuron selectivity for relational features immediately generalized to the new situation. These neural patterns offer a window into the network-level processes by which the mPFC develops a knowledge structure of the world that can be adaptively applied to new experiences.

“Generalizable knowledge outweighs incidental details in prefrontal ensemble code over time” by Mark D Morrissey, Nathan Insel, and Kaori Takehara-Nishiuchi eLife. Published online February 14 2017 doi:10.7554/eLife.22177

Do you have Selective Attention?

It’s the season for parties, get-togethers and crowds.  Have you ever had trouble putting background noise in the background and focusing on the conversation that is in front of you?

This discovery may hold the key to explaining why some people, who do not have hearing problems, still find it difficult to keep track of conversations in large crowds.

A group of neurons in the auditory processing areas of the brainstem help us to tune into specific conversations in a crowded room.

It could be that the neurons in their auditory brainstem, associated with receiving pitch signals, are not properly activated. 

This process of focusing on the voice of the speaker is called “selective attention” and that it happens in the part of the brain called the auditory cortex, which processes speech information.

Selective attention helps the brain to modulate sound information and to prioritize information over the background noise, such as focusing on one conversation above all others in a crowded room. However, what triggers selective attention in the auditory cortex has been debated by scientists.

Frankly Freddie – A man for ALL seasons (and a calendar too)

Santa CLAUStrophobia:

Fear of fly-by night men who are partial to the color red, use environmentally appropriate transportation and make their employees wear pointy shoes.

This phobia is often triggered by anticipation of shoveling snow and spending time with relatives in closed quarters.   It is characterized by over-spending, over-indulging, delusions of family harmony, leaving cookies and milk out to spoil and . . .  lying to children.

Have a HUMAN(E) Christmas!

Lickingly LLLLLLLLLLLLLLLLLLLLLLLLLLLL,

Freddie

P.S.  My Humans say to tell you to have a DOG-GONE

Merry Christmas AND . . .

buyEVERYTHING I KNOW ABOUT MEN I LEARNED FROM MY CAT2020 Calendar

It’s the purrrrfect mini size –  6 3/4″ w x 5 1/4″ H

Remember 50% goes to

The Gentle Barn Charity!

Click HERE to get your 2020  mini calendar

Click HERE to get your calendar

ai yiiii yiiiiiii – My Brain on Sugar and Acrylic Paint

Earlier this year I decided to eliminate sugar, hoping to reduce the inflammatory response that is common to fibromyalgia (and many other chronic conditions).  I LOVE sugar and didn’t want to banish it from my life so decided to use it as a subject in my paintings.

judy’s sugar-free, acrylic Donuts

I’ve always maintained my brain is hardwired to want sweets.  

Now I’m vindicated but also concerned enough to continue using my hand to paint rather than my mouth to eat.  Here’s why:

Dopamine “hits” from eating sugar

“On an evolutionary basis, our primitive ancestors were scavengers. Sugary foods are excellent sources of energy, so we have evolved to find sweet foods particularly pleasurable. Foods with unpleasant, bitter and sour tastes can be unripe, poisonous or rotting — causing sickness.”

“To maximize our survival as a species, we have an innate brain system that makes us like sweet foods since they’re a great source of energy to fuel our bodies.”

“When we eat sweet foods the brain’s reward system — called the mesolimbic dopamine system — gets activated. Dopamine is a brain chemical released by neurons and can signal that an event was positive. When the reward system fires, it reinforces behaviours — making it more likely for us to carry out these actions again.”

Dopamine “hits” from eating sugar promote rapid learning to preferentially find more of these foods.

“Our environment today is abundant with sweet, energy rich foods. We no longer have to forage for these special sugary foods — they are available everywhere. Unfortunately, our brain is still functionally very similar to our ancestors, and it really likes sugar. So what happens in the brain when we excessively consume sugar?”

Can sugar rewire the brain?

“The brain continuously remodels and rewires itself through a process called neuroplasticity. This rewiring can happen in the reward system. Repeated activation of the reward pathway by drugs or by eating lots of sugary foods causes the brain to adapt to frequent stimulation, leading to a sort of tolerance.”

“In the case of sweet foods, this means we need to eat more to get the same rewarding feeling — a classic feature of addiction.”

The brain wants sugar, then more sugar

“Regardless of our need for food to power our bodies, many people experience food cravings, particularly when stressed, hungry or just faced with an alluring display of cakes in a coffee shop.”

“To resist cravings, we need to inhibit our natural response to indulge in these tasty foods. A network of inhibitory neurons is critical for controlling behavior. These neurons are concentrated in the prefrontal cortex — a key area of the brain involved in decision-making, impulse control and delaying gratification.

Inhibitory neurons are like the brain’s brakes and release the chemical GABA. Research in rats has shown that eating high-sugar diets can alter the inhibitory neurons. The sugar-fed rats were also less able to control their behavior and make decisions.”

“Importantly, this shows that what we eat can influence our ability to resist temptations and may underlie why diet changes are so difficult for people.”

“A recent study asked people to rate how much they wanted to eat high-calorie snack foods when they were feeling hungry versus when they had recently eaten. The people who regularly ate a high-fat, high-sugar diet rated their cravings for snack foods higher even when they weren’t hungry.”

This suggests that regularly eating high-sugar foods could amplify cravings — creating a vicious circle of wanting more and more of these foods.

judy’s acrylic sundae

Sugar can disrupt memory formation

Another brain area affected by high sugar diets is the hippocampus — a key memory centre.

“Research shows that rats eating high-sugar diets were less able to remember whether they had previously seen objects in specific locations before.”

“The sugar-induced changes in the hippocampus were both a reduction of newborn neurons, which are vital for encoding memories, and an increase in chemicals linked to inflammation.”

How to protect your brain from sugar

“The World Health Organization advises that we limit our intake of added sugars to five per cent of our daily calorie intake, which is 25g (six teaspoons).”

“Importantly, the brain’s neuroplasticity capabilities allow it to reset to an extent following cutting down on dietary sugar, and physical exercise can augment this process. Foods rich in omaga-3 fats (found in fish oil, nuts and seeds) are also neuroprotective and can boost brain chemicals needed to form new neurons.”

“While it’s not easy to break habits like always eating dessert or making your coffee a double-double, your brain will thank you for making positive steps.”

“The first step is often the hardest. These diet changes can often get easier along the way.”

I didn’t get any hits of dopamine by the smell of acrylic paint nor did I experience a vicious circle of wanting to paint more and more . . . so far so good.

https://neurosciencenews.com/sugar-brain-15216/

Peggy’s Read – The Upside of Stress

I read 2-3 books at the same time: One is for chilling out (usually a mystery), one is for the book group I’ve belonged to for years and one is because I love science.

My latest read, by Kelly McGonigal, PhD, “The Upside of Stress: Why Stress is Good for You and How to get Good at it”, was enlightening.

McGonigal was interested in a longitudinal (1998- 2016) study of 30,0000 adults, showing that high levels of stress increased the risk of dying by 43% BUT ONLY if the person believed stress was harmful. (PA)

Those with high stress levels who did not believe it was harmful to their health had the lowest risk of death, lower than those who had little stress.

Popular opinion has been to avoid stress because it’s harmful.  This book made me rethink avoiding stressful situations and reframing stress as a challenge and help build resources and confidence.

Stress? Or a challenge? 

Here’s some of the interesting research and information from The Upside of Stress: Why Stress is Good for You and How to get Good at it”:

Simply watching a” stress is enhancing” video to change someone’s mindset made a difference in the participants hormones that are produce during stress: cortisol and DHEA. The ratio of the two, called the growth index, determines the effects of stress. Higher levels of DHEA help people thrive under stress, and be resilience when stress is very high.
The researchers followed over time two groups:  a mindset change group that watched videos of the positive effects of stress and examples of thriving under stress and a control group that didn’t see the videos.  The group that was exposed to the positive effects of stress:

  • Continued to see stress in a more positive way.
  • Their depression and anxiety was reduced
  • Had fewer health problems
  • Were more focused and more productive.
  • These brief trainings resulted in lasting change.

There was no change in the control group.

Maybe non-life threatening stress should be called

the “challenge response”? 

Stress? Or meaningful activity-or both?

Some positive aspects of stress the book details:

  • The most common response to acute (as opposed to chronic) stress in people is growth and resilience.
  • Fight or flight not only gives you a bodily response to stress but can increase motivation for change.
  • Experience with stress when it’s not life-threatening can increase resilience. This response increases energy and focus.  It releases higher DHEA, raising the growth index. Artists and athletes show this when engaged in skill.
  • Oxytocin improves empathy and decrease fear, and increases social connections.
  • DHEA and nerve growth factor increases neuroplasticity to help you learn from stressful events.
    Cortisol and oxytocin help decrease inflammatory response and help recovery

Studies show stressed people are happier, maybe because they are engaged in meaningful things… jobs, raising kids, and  other projects. A full, busy life is full of stress.

Sometimes it is good to try to cam down, but other times it is better to say “I’m excited” when anxious. Cortisol and adrenaline actually improve performance during test taking,  Athletes say they are excited (rather than stressed) before a game which helps focus and determination to win.

When I think back to times I learned, changed and grew the most, high stress was ever present.  It was a fascinating read and while I still don’t relish most stressful situations I learned stress is ever present and whether I focus on the positive or negative aspects my brain, body and life are all impacted in critical ways.

Peggy

 

 

The Secret to Motivation

Fruit flies have been buzzing around my kitchen since I started recycling food waste for the environment.  Yes, yes, I’m using a special container provided by the city but those pesky flies still try to get in.  I can testify to their perseverance . . . and their ability to evade my swats. 

Perseverance and grit are important to work toward goals.  How do you stay motivated to do this? A team of researchers led by Technical University of Munich scientists have found one answer in the brain of a fruit fly. Yup,  fruit flies are ambitious and they can teach me something about staying with a task.  

The researchers set up the fruit flies so they would go after fruit that smelled, but was kept out of reach, while their little legs ran on balls which measured how fast they were running – how much effort they were making. The experiment showed that hungry fruit flies would continue increasing their speed, until they ran up to nine meters per minute. Fruit flies who had eaten would stop more quickly than the hungry flies.

Staying with it

The researchers identified a neural circuit in the flies  that appears to cause this perseverance.  We humans have a million times more neurons than the flies have which makes it easier to figure out what each neuron does. With the help of electron microscopy, the neural circuit was identified.This circuit is located in the learning and memory center of the fly brain. Two neurotransmitters, dopamine and octopamine, (similar to noradrenaline in humans) regulate the circuit. Dopamine increases increases motivation; octopamine reduces it.

It turns out that theses same chemicals are in the brains of people and scientists think they also regulate motivation.

It turns out that my own neural circuits are motivating me to rid my kitchen of fruit flies.

(jw)

“A Neural Circuit Arbitrates between Persistence and Withdrawal in Hungry Drosophila”. Sercan Sayin, Jean-Francois De Backer, K.P. Siju, Marina E. Wosniack, Laurence P. Lewis, Lisa-Marie Frisch, Benedikt Gansen, Philipp Schlegel, Amelia Edmondson-Stait, Nadiya Sharifi, Corey B. Fisher, Steven A. Calle-Schuler, J. Scott Lauritzen, Davi D. Bock, Marta Costa, Gregory S.X.E. Jefferis, Julijana Gjorgjieva, Ilona C. Grunwald Kadow.
Neuron doi:10.1016/j.neuron.2019.07.028.