In this video I discuss brain development and begin with the idea of infantile amnesia. Memories before about the age of 3 are very rare, suggesting that the infant brain is not yet developed to store episodic memories, though it can form other types of memories and associations. From age 3-6 our brains undergo a period of rapid progress and we develop billions more synaptic connections than needed. These ensure that needed pathways will be available, and those which are not needed are abandoned later during synaptic pruning. The environment also influences brain development and research by Rosenzweig, Krech, Bennett, and Diamond demonstrated how an impoverished environment would lead to smaller brain volume and fewer synaptic connections compared to environments which were “enriched”. It seems the most enriched environment, however, is the natural environment, which provides incredible amounts of stimulation and presents endless challenges for the developing brain.

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Video Transcript

Hi, I’m Michael Corayer and this is Psych Exam Review. In this video we’re going to take a look at brain development. Now if you ask most people about their earliest childhood memories, you’ll find it’s very rare for people to have memories before about the age of 3. And this is referred to as infantile amnesia and what it suggests is that our brains are not yet developed enough to begin storing episodic memories.

Now of course, we can learn other types of things in the period between birth and about age 3; we learn how to recognize and understand the language around us, we learn how to speak, we learn control over our movements and coordination, but we don’t yet have the ability to store episodic memories until about the age of 3. And then when this happens, it coincides with a period of very rapid progress in our brain development and in our mental abilities.

One thing that we see during this period is that we grow many more synaptic connections than we will actually need. Between the age of about 3 and 6 we’ll grow an additional 3 to 6 billion synaptic connections, and this helps to ensure that we’ll have the connections and the pathways that we might need in the future when we need them. But it also means that we have too many connections, and we don’t keep these. So before puberty we’ll go through a process referred to as synaptic pruning, and this is where we actually lose a number of these extra connections.

And we can also think about the role the environment has on our brain development and this brings us to some research that was conducted by a number of researchers, a team of researchers, including Mark Rosenzweig, David Krech, Edward Bennett, and Marian Diamond, conducted over a number of years in the 1960s and 70s. And what these researchers looked at was the development of rat brains in different environments. So they compared rats who were raised in an empty cage, which was the impoverished environment, to rats that were raised in cages that included toys, ladders, running wheels, and tunnels, and this was referred to as an enriched environment. What they found is that the rats who were raised in this enriched environment had larger brain volumes; they had more synapses, in fact the synapses were also larger, so this suggested that this enriched environment was playing in a important role on the rats’ brain development.

So how might we apply this to humans? Does this mean we need to enrich the human environment for our infants? If we have a child do we need to put more toys into the crib and give them more things to play with in order to ensure that their brains will develop fully? Well, not quite, because additional research by these same researchers showed that the enriched environment wasn’t as enriched as they thought. Because they began some studies where they compared it to the natural environment. And this idea that it was an “enriched” environment is not quite accurate; it turns out it was a less impoverished environment. Because if they compared animals who were raised in a natural environment to those raised in this enriched caged environment, they found the natural environment led to even larger brain volume and even more synaptic connections.

So this brings up the important point that the natural environment is full of stimulation. It’s incredibly stimulating and so we don’t need to worry too much about one more toy making a huge difference in an infant’s brain development, right? We don’t need to worry about playing Mozart music in the background to ensure that our child is going to grow more synaptic connections or have a larger brain volume, because the problems that infants are already trying to solve are incredibly difficult problems, that are incredibly stimulating.

So if you think about the problems in infants trying to solve you realize just how large these are. I mean, they’re trying to understand social interaction, they’re trying to learn coordination of all their muscles in their body and how to control their voluntary movements. They’re trying to understand the language around them and also learn to coordinate the muscles and the activity needed in order to produce that language. And this shows us that these are incredibly difficult problems and the environment that’s already so stimulating. They’re also learning how to make sense of all the sensory information that’s coming in from all of their senses. They have a lot to do and their brains are working very, very hard to make sense of all this. And so an additional toy is probably not going to make a big difference.

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