There is a developing body of research that suggests human brains continue developing roughly until age 25.
So if our brain completes development by our mid to late twenties, do we cease to make new neural connections?
Is the old saying, “you can’t teach an old dog new tricks,” true?
Fortunately for us, new neurons are created everyday and are incorporated into our existing neural networks (Belzung & Witmore, 2013). You can, in fact, teach an old dog new tricks.
Neural plasticity, or the ability for our brain to change and make new connections, occurs throughout our lifetime. So yes, you can in fact teach an old dog new tricks! This explains how Betty White, in her mid-nineties, is more savvy at Twitter than I am (as evidenced by my 1 follower, to you I say "thank you").
SO, What is the difference between learning that happens in a developing brain and learning in an adult brain?
During development, neural growth occurs by widespread cell proliferation. In other words, cells rapidly multiply and form new connections throughout the developing brain. In contrast, the adult brain forms new neurons primarily in the hippocampus. The new neurons that are created in adulthood are then linked into existing neural networks. This brings us to the million-dollar question:
How do we create new pathways in our brain, and how do we remember these new pathways?
There exists a critical period after neurons are created, in which they are shaped by experience. When we learn something new, we plug it into our existing neural networks. In other words, we connect the new information we have with something we already know. These connections are called synapses. We make associations. This is one reason pneumonic devices work so well.
Synapses are like roads in our brains. Everytime we learn something new, we make a new road branching off of an existing highway in our brain. We don’t just create one new road though, we create many. We create a new road from our visual cortex, our auditory cortex, and other regions of our brain depending on what we are learning.
The more we drive those roads, the faster we become at the task, whether it is a new skill or remembering a piece of information. It's a lot like snow-sledding. The first run down a hill takes some time, you have to carve out your path and press it down. The more runs you do, the faster the sledding path becomes. This is why repetition and practice are key in learning and remembering something new. To get it to stick, you have to continue to access it and practice it.
Our brains are incredibly efficient. Just like a good gardener prunes dead branches to make way for new branches, the brain prunes information from our brains that is not regularly accessed. This is why it’s hard for many of us to remember math we learned in high school.
Neuropsychologist Donald Hebb coined the phrase, "neurons that fire together, wire together." The more pathways we engage at the same time, the more associated they will become.
For example, let's say your favorite movie is Star Wars, and I ask you to think of the original series. You will remember what Luke looks like, how Yoda sounds, the emotion of shock you experience when (spoiler alert) Vader revelead he was Luke's father. You may be able to even smell the popcorn and feel the warmth when you were curled up next to your dad watching it at a family movie night. All of your senses were firing as you encoded one memory.
The stronger the input, the greater the associations. If you can make something significant- either associating with with a strong emotion or physical sense, it will be more likely your remember it.
For an excellent talk on this principle, check out Max Cynader's talk on enhancing the plasticity of the brain below.
Beyond repetition, how else can we improve our memories?
SLEEP. Countless studies have found that what we learn during the day is re-played and processed while we sleep. Our hippocampi are very busy while we sleep, replaying and fortifying our neural connetions. Sleep is critical for storing, processing, and increasing memory.
EXERCISE, particularly cardiovascular exerise (like running), has been found to increase cell formation (Leuner & Gould 2010).
SEX, like exercise, has been found to increase cell formation and differentiation in the brain. Both novel and recurrent sexual experiences are promising for cell creation (Leuner & Gould, 2010).
FOOD. The brain is nearly 60% fat, making fatty acids an essential part of mainting optimal brain functioning. Not all fats are created equal, and the kind of fat that your brain needs include decosahexaenoic acid (DHA). The best source of DHA are Omega 3 fatty acids. Additionally the brain needs protein which are full of amino acids, the building blocks of the brain. Vitamins, specifically B12, and antioxidants are also key in brain health.
Foods for Optimal brain health, focus, and memory:
Leafy greens (spinach, kale, chard)
Seeds (pumpkin, sunflower, chia, flax)
BRAIN TRAINING. We can strengthen our neural pathways by working them out. Intellectually stimulating activity such as reading, crossword puzzles, sudoku, learning something new, or even brain-training programs like Lumosity help us create and strengthen new pathways. Stimulating, enriching environments, and learning something new are essential in brain cell prolifreation and maintenece. (Leuner & Gould, 2010)
More and more data is coming out on the negative effects of stress, alcohol, sugar, and inflamation, and brain health can be added to that list. Sugar and alcohol lead to inflamation, so they should be avoided when possible (Belzung & Witmore, 2013).
So you want to improve your memory and mental health?
Get a good night sleep, get your heart pumping with exercise, get jiggy with it, eat well, and challenge yourself to learn something new each day. Keep those synapses firing!
Belzung, C., Witmore, P. (eds). 2013. Neurogenesis and neural plasticity. Berlin, Germany: Springer.
Leuner B, Glasper ER, Gould E (2010) Parenting plasticity. Trends Neuroscience, 33, 465–473.
Leuner B., Glasper E.R., Gould, E. (2010) Sexual experience promotes adult neurogenesis in the hippocampus despite an initial elevation in stress hormones. PLoS One, 14 (5).