At the Gates of Sleep

497736998_45c09a136e_oNow that my daughter is about to reach her first birthday, I’m in the mood to reflect on the year that just passed. Unfortunately, my recollections of it are a little fuzzy, probably because I can count on one hand the number of times I’ve enjoyed a good night’s sleep over the past year. Some people have babies who regularly sleep through the night and I am happy for them. Truly, I am. But clearly I was not meant to be in their ranks.

Still, the never-ending parade of nighttime awakenings has taught me something about my own brain. It is precisely tuned to hear my baby. Although I sleep blithely through my husband’s thunderous snoring and the loud buzz of his alarm clock – multiple times a day, thanks to the snooze button – I awaken at the faintest sound of my daughter’s sighs, coos, or grumbles. When she cries, I am immediately awake while my husband sleeps on beside me, undisturbed.

People are generally able to sleep through minor sounds and sensations thanks to a subcortical structure in the brain called the thalamus. This structure receives incoming signals from our senses and relays them to cortical areas devoted to processing sensory information like sounds or tactile sensations. When we’re awake, the thalamus faithfully relays nearly every sensory signal on to the cortex. But when we’re asleep, neurons in the thalamus participate in strong, synchronized waves of activity that squelch incoming signals. As a result, about 70% of these signals never make it to the cortex. This process, known as sensory-gating, is how we manage to sleep through the roar of rainstorms or the brush of the sheets against our skin each time we turn in bed. It is also how we sleep through our husband’s room-rattling snores.

Yet some sensory information does get through to the rest of the brain during sleep. These signals do get processed and can even wake us up if they are either intense (like a loud noise) or personally relevant. A clever study illustrated the importance of personal relevance by exposing sleeping subjects to a loud presentation (via tape recorder) of their own name spoken aloud. The scientists played the recording either normally or backwards and found that subjects awoke in less than half the time when they heard their names presented in the recognizable form.

So did my daughter, in effect, sleep train me by training my brain to recognize her sounds as personally relevant? It’s a plausible explanation, but one that is ultimately lacking. It cannot explain that first night when I slept beside my baby at the hospital nearly one year ago. Although I had labored through the entire night before and had not slept in the ensuing day, I awoke constantly to every little sound my mewing newborn made, not to mention the cries that told me she wanted to nurse. She’d had no time to train me; I had come pre-trained. Just as my breasts were primed to make milk for her, my brain was primed to wake for her. We seemed to be engineered for one other, mother and child, body and brain. And we spent that first long night discovering how clever a designer Nature can be, while my husband slept peacefully on the couch.

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Photo credit: planetchopstick

Tooling Around

tools1There was a time when my daughter used her hands exclusively to shovel things into her mouth. Not so anymore. For the last few months, she has been hard at work banging objects together. This simple action is setting the stage for some pretty cool neural development. She is learning to use tools.

Of course it doesn’t look too impressive right now. She might bang a ball with a block and then switch and strike the block with the ball. In one recent playtime she tore a cardboard flap out of her board book and examined it, trying different grips and holding it from different angles as she watched how it cut the air. Then, brandishing her precious flap, she went to work. She wielded it with a scooping motion to lift other flaps in the book, and later, to turn the book pages themselves. After that, she descended on her toy box with the flap. She used it to wipe her blanket, poke her stuffed animal, and finally scrape its face like she was giving it a close shave.

Although my daughter’s fun with flaps may seem aimless, it had an important purpose. Through experimentation and observation, she was learning how two objects can interact and how such interactions are affected by object shape, configuration, and pliability. Such details are so well known to adults that we forget there was anything to learn. But consider how often we use objects against one another. We hammer nails, rake leaves, and staple pages. When using scissors, we must apply different levels of force to cut through paper versus cardboard or fabric. When lifting a pan with a potholder, we must adjust our grip depending on the weight of the pan and whether we are lifting it by the base, side, or handle. We must know the subtle differences between holding a sponge to wash a glass and using a towel to dry it, and we must do each deftly enough that our glassware comes out clean and intact at the end.

There are also countless tools we create on the fly every day. When you use a magazine to nudge your cell phone within reach or flip a light switch with a book because your hands are full, you are devising novel tools to fit your momentary needs. To do this, our brains must store extensive knowledge about the properties of household objects. Through experimentation, like the kind my daughter is doing, we learned to predict how objects will interact and to capitalize on those predictions.

So far I’ve described the value of tools in terms of what they can do: push, pull, gather, polish, lift, etc. But there is another side to tool use that may play a role in my daughter’s little experiments: sensory information gleaned through the tool. As I watched her probe one object with another, I was reminded of research described in Sandra and Matthew Blakeslee’s book The Body Has a Mind of Its Own. The book discussed neurons in the parietal cortex that are tuned to the sight or feel of objects near a particular body part. For example, cells representing your right hand would fire if something touched your right hand, if you saw an object near your right hand, or both. Neuroscientists have discovered that experience using a tool can change the properties of these cells in monkeys (and therefore likely in us as well). They found that if monkeys used a rake to gather goodies otherwise beyond their reach, the parietal neurons that had responded to objects around the hand now fired for items located anywhere along both the hand and the rake it held. In a sense, object manipulation can temporarily extend certain neural body representations to include the tools we wield. The Blakeslees suggest that this may be how a blind person learns to perceive the contour of items encountered at the tip of his cane. In effect, the cane and the hand are one.

For now, our house is filled with smashing, scraping, banging and bending as our baby descends on toys and her parents’ belongings alike. In the midst of such havoc, it’s good to know that the destruction is part of a crucial learning process. And someday, once it slows down, I can buy her a new board book with all the flaps intact.

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Photo credit: zzpza

Say What?!

Although I grew up outside of Chicago, I’ve spent the last decade split between the East and West Coasts. Now, after 5 years in Los Angeles, my husband and I are settling into life as Michiganders. Aside from the longer days and lower cost of living, the biggest differences I’ve noticed are linguistic. People speak differently here, and for me it’s like coming home. After a decade away, I am back in a state where people drink pop instead of soda. And, at long last, I’ve returned to the land of the Northern City Vowel Shift.

Speech is constantly in flux, whether or not we are aware of it. Regional dialects diverge, giving us the drawls of the South and the dropped r’s of the Northeast. More recently, cities in a large swath of the northern Midwest are reinventing their vowels, especially the short vowels in ben, bin, and ban. From Syracuse to Minneapolis, Green Bay to Cleveland, these vowels have been changing among Caucasian native English speakers. The vowels are now pronounced with a different positioning of the tongue, in some cases dramatically altering the sound of the vowel. A wonderful NPR interview on the subject is available online in audio form and includes examples of these vowel changes.

I must have picked up the Northern City vowels growing up near Chicago. When I arrived in Boston for graduate school, friends poked fun at my subtle accent. They loved to hear me talk about my can-tact lenses. And I can’t blame them for teasing me. The dialect can sound pretty absurd, especially when pushed to the extreme. It was probably best parodied by George Wendt and the SNL cast in the long-running Super Fans sketch.

I have long been in love with the field of phonetics and phonology, or how we produce and perceive speech sounds. Creating and understanding speech are two truly impressive (and often underappreciated) feats. Each time we speak, we must move our tongues, lips, teeth and vocal folds in precise and dynamic ways to produce complex acoustical resonances. And whenever we listen, we must deconstruct the multifaceted spectral signatures of speech sounds to translate them into what we perceive as simple vowels, consonants, syllables. We do all of that without a single conscious thought – leaving our minds free to focus on the informational content of our conversations, be they about astrophysics or Tom and Katie’s breakup.

Experiences in the first couple years of life are critical for our phonetic and phonological development. Details of the local dialect are incorporated into our speech patterns early in life and can be hard to change later on. As a result, everyone’s speech is littered with telltale signs of their regional origins. My mother and aunt spent their early years in a region of Kansas where the vowels in pen and pin were pronounced the same. To this day, they neither say nor hear them as different. Imagine the trouble my mother had when she worked with both a Jenny and Ginny. I’ve noticed major differences between my husband’s dialect and my own as well. My husband, a native Angeleno, pronounces the word dew as dyoo, while I pronounce it as doo because in Chicago the vowels yoo and oo have merged.

These days I’m watching phonetic development from a front-row seat. My baby has been babbling for a while and I’ve watched as she practiced using her new little vocal tract. She would vocalize as she moved her tongue all around her open mouth and presumably learned how the sound changed with it. From shrieks to gasps to blowing raspberries, she tested the range of noises her vocal tract could create.  And as she hones in on the spoken sounds she hears, her babbling has become remarkably speech-like. The consonants and vowels are mixed up in haphazard combinations, but they are English consonants and vowels all right. Through months of experimentation, mimicry, and practice, she has learned where to put her tongue, how far to open her mouth, and how to shape her lips to create the sounds that are the building blocks of our language. And just as she was figuring it out, we went and moved her smack into a different dialect. She will have to muddle through and learn to speak all the same. And once that happens, it will be interesting to see where her sweet little vowels end up.

On Nano-Naps and Dreamscapes

New mothers must be collectors of broken sleep, eagerly taking a sliver here, a shard there – whatever they can get.

Now that my baby is four months old, she’s finally sleeping at night. Still, she wakes me every two hours to nurse. She is half asleep while she feeds and I am always nodding off. In the few seconds it takes for my sinking head or my nursing baby to summon me back, I’ll have a momentary dream. A micro-dream. A nano-nap. No more intricate dreams of forgetting to do my homework or going to prom in a maternity dress. These dreams are all business: snapshots of everyday life. Once it may be a view of my husband lifting the baby out of her crib. Another time, I glimpse a lump in bed beside me and realize it’s my baby buried in our blankets (a terrifying dream.) But usually I simply dream that she’s nursing. A dream of mere reality: no more, no less.

How do I even know that I’m dreaming? The details are off. And in these cases, the switch from dreaming to wakefulness can be particularly strange. Once the transition felt as seamless as a change of camera shots in a television show. One moment I was looking down at my nursing baby; the next, she was flipped (mirror-reversed) in my arms and her head was noticeably smaller! Never before have I had such an immediate comparison between the mind’s eye and the naked eye, nor realized how very similar they feel. And never before have I had such uninventive, literal dreams. It’s as if I can’t muster the energy to dream up anything better.

In the face of my lackluster dreaming, I am all the more fascinated by the rich dream life of my daughter. From the day she was born I’ve watched her smile, pout, and wince and heard her scream and giggle madly in her sleep. In fact, she smiled in her sleep months before she gave us her first waking smile. Physicians have observed rapid eye movements in fetuses, suggesting that babies dream in the womb. But what are they dreaming of? Is it limited to what they know: heartbeats and jostling and amniotic fluid? Or perhaps their dreams are wilder than our own, unconstrained by the realities of life on this earth. After all, the infant brain contains legions of unpruned synapses and far more neurons than that of an adult. Who’s to say what sort of fantasy it might come up with?

Whatever sort of dreams a newborn has, we don’t remember them as adults. By late infancy, we’ve already pruned enough synapses and experienced enough of the world to have a basic vocabulary for our dreams. An adult’s dream may create some odd combinations – eyeballs growing on trees or hats that unfurl into snakes – but the vocabulary, the unitary elements, are fixed. Eyeballs, trees, hats, snakes. Grow, unfurl. Our potential dreamscapes are wholly constrained by the details of our waking existence.

As my baby examines new places and things, I am reminded that she’s cobbling together her own vocabulary of the world. She will store away sensations, objects, creatures, actions, concepts, cultures, and myths. A knowledge that the sun shines from above and plants sprout from below. That rivers run and lakes loiter. That caterpillars turn into butterflies and never the other way around. For better or for worse, her future dreams will be shaped by the idiosyncrasies of our funny little world.

Dreaming of Me

My belly button has all but disappeared. In its place, an odd little pillow of skin lies flush with the rest of my stomach. A dark line – the linea nigra – now runs down the length of my abdomen, dividing me in two. My appendix and intestines, previously at home in my abdominal cavity, have been pushed up and to the sides so that they now form mysterious bulges just below my ribs. Stranger still, I find myself in possession of someone else’s breasts. And then there’s the most noticeable change: the beach ball sized stomach that wholly eclipses my view of my feet.

Of course these changes didn’t come on all at once. I’ve had many months to notice and adjust to them. Still, they’ve happened more rapidly than any other physical changes I’ve experienced in my life. Faster than an adolescent growth spurt, certainly, or any weight gain or loss. My brain has had trouble keeping up. I bump into things with my belly, forgetting its size. I struggle to maintain my balance as my vestibular system tries to adjust to my changing weight distribution. But the lag that has fascinated me most is how I envision myself in my dreams.

Even months into my pregnancy, after my stomach had visibly ballooned, the self I inhabited while dreaming remained as lean as ever. Although thoughts of my pregnancy filled my waking hours, at night I wasn’t the least bit pregnant. In fact, I often dreamt of myself as a high schooler again, wandering the halls without a class schedule or scrambling to find a bus that would deliver me there on time. Why high school? I don’t put much stock in the elaborate interpretation of dream symbols, but I imagine that my dreams of being a lost high school student reflect my waking awareness that parenthood is at my doorstep and I am unprepared. In the face of such a dramatic life change, I can’t help but feel that I’ve lost my lunchbox or forgotten a homework assignment somewhere.

Then, a month or so ago, my dreams began to change. Or rather my dream self changed. My new self often had a swollen midsection and wore maternity clothes (or in one case, a maternity prom dress). She couldn’t drink alcohol and got worn out just walking from the car. The dreams weren’t usually about my pregnancy; my enormous belly was simply present, just like my arm, hands, and feet. Something about my self-image, my internal body schema, had updated. A switch had been flipped and my mind was caught up with my changing body.

I began to wonder about these internal self-schemas that reveal themselves in our dreams. Do other pregnant women experience the same switch and a similar lag? And how long does it take for them to switch back after they’ve delivered their babies? What about other changes to one’s appearance, like growing or shaving off a beard? Or, in a more dramatic example, what happens when someone loses a limb?

I haven’t found much written on baby bumps and beards, but several people have studied whether amputees dream of themselves with intact or amputated bodies. The answer, in short, is it depends. One study found that a majority of surveyed amputees dreamt of themselves with amputated bodies at least some of the time. Among them, 77% made the switch within the first 6 months following their amputations. But the study also showed that a surprising percentage of the surveyed amputees (31%) dreamt exclusively of themselves with intact bodies, even a decade or more after their amputations. Preliminary findings suggest that those who undergo the amputation at a later age, those who regularly use a prosthetic limb, and those who experience phantom sensations from the missing limb may all be more likely to dream with their bodies intact.

It should come as no surprise that the results of the studies are complicated and variable. We can’t expect anything as complex as dreams and internal self-representations to be wholly consistent from person to person or from one dream to another. In my case, I may be pregnant in one dream but not in the next. At times I even dream I’m someone other than myself. Wading into dreams can be a messy business, certainly, but my curiosity is piqued and I’m eager for more data. To all those pregnant or post-pregnant ladies, beard growers, or head shavers out there: please comment and share your experiences! How long did it take for your dream self to catch up with the real thing?

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Photo credit: Sabin Dang

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