Pregnancy Brain: A Neuroscientific Guide for the Expectant Mom (Part 1 of 2)

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My friend recently asked me, “Why have I become so forgetful since I became pregnant?” I told her I didn’t know, but that I’d look into it and write an article for her.

She then followed with, “I was going to ask you to explain something else to me, but I totally forgot what it was.”

Does “pregnancy brain” actually exist? There’s no doubt that many changes are happening to a woman’s body during pregnancy, but how do these changes affect (or originate in) the brain? To answer my friend’s question – and in an effort to address whatever else she was forgetting at the time – here is Part 1 of my expectant mom’s guide to the crazy neuroscience of pregnancy.

What the Heck is Déjà Vu? Why Do I Get It and Some People Never Do?

Erika Wittlieb (Pixabay)

What is déjà vu?  Many of us know the feeling. You'll be going about your day, minding your own business, folding some laundry...nothing out of the ordinary. Suddenly a sensation of familiarity washes over you, and you're completely aware that it's happening. I've been here before. Except you haven't. Or have I? You might try to think back and pinpoint when you'd experienced this moment before. But just as quickly as the feeling hits you, it's gone again.

Did you predict the future? Were you seeing something from a past life? What the heck is déjà vu, anyway?

Perhaps unsurprisingly, déjà vu (French for "already seen") is, scientifically, pretty poorly understood. There are a few theories, however:

University of Bristol

• Déjà vu may be the result of some sort of "mismatch" in how we're simultaneously sensing and perceiving the world around us. Perhaps we smell something familiar, for example, and our mind is instantly transported to the first time we smelled it. (It's a vague theory, though, and doesn't explain why most déjà vu episodes don't reflect true past events.)
• Déjà vu may be a fleeting malfunctioning between the long- and short-term circuits in the brain. The information our brain takes in about its surroundings may "shortcut" its way straight to long-term memory, bypassing typical storage transfer mechanisms. When we have a moment of déjà vu, it feels as though we're experiencing something from our distant past. 
• A region of the brain called the rhinal cortex, involved in detecting familiarity, may be inexplicably activated without actually activating memory (hippocampal) circuits. That may explain why déjà vu episodes feel so non-specific when we try to figure out where and when we had previously experienced a particular moment. In fact, some patients with epilepsy reliably experience déjà vu at the beginning of a seizure. For these individuals, experimental stimulation of the rhinal cortex — and not so much the hippocampus itself — induces déjà vu.

Déjà vu is estimated to occur in 60-70% of people, and most commonly in those between the ages of 15 and 25 years. (Why? No idea.) Interestingly, I had previously written about déjà vu years ago out of my own curiosity on the matter, having experienced it fairly frequently. I'm now 26, though, and can't remember the last time I had an episode.

Are any of these theories correct? We may never know. After all, an episode of déjà vu is completely unexpected and, for most of us, extremely rare. Empirical research on the topic is next to impossible.

The most parsimonious explanation, then, is likely the following:

What about you?
Do you experience déjà vu?
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In this anonymous poll!

Why Do I Only Remember Certain Things in Certain Places?

Why do I only remember certain things in certain places?  I'm glad you asked, because this happens to me all the time. I'll think about something, get off the couch and go to the kitchen to do whatever I told myself I needed to do, then completely lose my train of thought. Why did I come in here, anyway?

Man Vyi (Wikimedia Commons)

Funny enough, psychologists have actually studied this.

In a 2011 paper, Gabriel Radvansky and colleagues from the University of Notre Dame had participants play a computer game. In a virtual room, they were instructed to pick up an object from a table and take it to another table. The objects varied in color and shape. Importantly, as long as the participant was "carrying" the object, it was invisible to them.

Sometimes the participants' video game characters simply had to cross the room to put the object down. Other times, they had to walk through a virtual doorway to get to the table.

At random times throughout the experiment, participants were asked what object they were currently carrying. Interestingly, walking through a virtual doorway resulted in less accurate and slower responses than when they simply needed to cross a room.

MetroParent

But why? The authors suggest that we keep information in our working memory for as long as we consider it relevant. But when something related to the context of our memory changes — like the room we're in when we think about something — the memory must no longer be important enough for us to remember. Our brains probably think they're helping out by purging that memory for us. This is consistent with the hypothesis that, in general, recently-formed memories are extremely vulnerable to many interfering forces if they have not yet had a chance to consolidate.

To answer the broader question: we associate certain memories with certain places, and that's how we make sense of all the input flooding into our noggins. Our brains have incredible storage capacity, but they can only do so much. (Elephants* never forget, though.)

Do you forget more
When you walk through a door?
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In this anonymous poll!