Category Archives: Brains

Good Morning, Sleepyhead

March 5, 2011 By in Books, Brains, Life Tags: , , , 1 Comment

A few weeks ago, I passed out. One moment I was standing by the door to our apartment, wishing my departing husband a good day at work. The next, my eyes had rolled back in my head and I fell face-first into the wall. My forehead struck the lower hinges of the door; I bruised my cheek and arm and knee, nothing badly. My husband, who was halfway out the door when I fell, rushed to gather me up. He held me and said, “Are you all right? Are you okay?” And that was how I awoke, as if from a long dreamless sleep, on the floor beside our front door.

I was only out a few seconds, but it felt like it could have been hours. I remembered the minutes leading up to my dramatic tumble, but they felt like long ago. A bit ethereal, and separated from the present by a gap that didn’t feel odd to me in the slightest.

I’ve always tended toward low blood pressure and often felt dizzy when standing up. After the fall, doctors checked me out and said I was fine. (My prescriptions are to drink more water and maybe eat more salt.) Still, the experience got me thinking about memory and how it’s a strange and elusive creature. How we always think we’ve caught it but we never have.

Back in my grad school days, we studied the case of H.M., the famous amnesic patient who was unable to form new memories. We learned that his journal was filled with descriptions of waking up as if for the first time and having no recollection of writing any of the prior journal entries, nor of how he came to be where he was. I wonder if the feeling was something like my contradictory experience on the floor, when I lacked memory of the preceding moments and yet felt as if nothing were missing. Time felt continuous, despite the fact that my memory was not.

The experience also reminded me of a dramatic story I read in the nonfiction book Soul Made Flesh. In 1650, a young British servant named Anne Green was seduced by her master’s grandson and gave birth to a stillborn baby. Thanks to the social mores of the time, she was tried and convicted of infanticide and sentenced to death. She proclaimed her innocence to the crowd that gathered in the courtyard of Oxford Castle to watch her hanging. After her speech, the executioner kicked the ladder out from under her and she hanged for almost half an hour before they cut her down and sent her body down the street to be dissected for science. Her designated dissectors were Drs. William Petty and Thomas Willis (of the Circle of Willis). But when they opened the coffin, they heard a rattle in her throat and managed to revive her with water, heat, and herbs.

When Anne Green came to, she began reciting the speech she’d delivered at the gallows. She didn’t remember leaving the prison, climbing the ladder, or giving the speech, much less (thankfully) hanging. A pamphlet later circulated about the event described her memory as “a clock whose weights had been taken off a while and afterward hung on again.” The incident illustrated the machine-like quality of memory. Today we describe it as flipping a switch. Anne Green’s memory had been turned off and then turned on again.

As strange as the stories of H.M. and Anne Green sound, their wild memory lapses aren’t so different from what happens to us everyday. We all experience time as continuous and ongoing, even though our memory is often shot through with holes. We spend a full third of our lives in unconscious slumber and remember little of our dreams. Even our waking lives are terribly preserved in the vault of our memory. How many of your breakfasts can you recall? How many birthday parties and drives to work? How many classroom lectures and airplane rides and showers can you individually call to mind?

Our recollections are mere fragments. They pepper the timeline of our past just enough to form a narrative – one’s life story. This story may feel solid and unbroken, but don’t kid yourself. Your memory is not. We are all amnesic, all a little untethered from the passing moments of our lives. We are continually rediscovering and resurrecting our past to move forward in the present. In one way or another, we have all roused from our coffin reciting a speech from the gallows or come to on the floor with a sore face and an astonished husband. We are all perpetually in the process of waking up for the very first time.

Why Bigger Isn’t Always Better

January 16, 2011 By in Brains Tags: , , , 1 Comment

One of my entertainments this holiday season was following the online buzz over a recent article in Nature Neuroscience. The authors’ findings were covered by Wired, Time, Slate, U.S. News & World Report, and the BBC, to name a few. One headline read: Scientists Discover Facebook Center of the Brain. Another: How to Win Friends: Have a Big Amygdala?

The authors of the Nature Neuroscience article report a correlation between the size of a subcortical brain structure called the amygdala and the extent of a person’s social network. In effect, people with larger amygdalas tended to have more friends and close acquaintances than those with lesser-sized amygdalas. The popular press and the public leapt on this idea. We are predestined by our anatomy to be popular or not. If we were alone on New Years Eve, if our Facebook friend count is low, it’s not our fault. Chalk that one off to our brains, our genes, our parents.

All of this struck me as both amusing and sad because of a book I was reading at the time. The book, Postcards from the Brain Museum by Brian Burrell, chronicles the history of neuroscience in the context of our search for greatness (as well as criminality, idiocy, and inferiority.) It tells how scientists spent most of the 19th century collecting human brains from geniuses, criminals, and the poor to try to understand why some people demonstrate remarkable abilities while others flounder and fail.

It is a sad and sordid history. At first, some believed that the sheer size or weight of one’s brain predicted greatness, so that large brains were capable of better thinking. Since women’s brains (like the rest of their bodies) were on average smaller than those of their male counterparts, this provided a perfect explanation for their intellectual inferiority. Later, when the link between brain volume and intelligence was debunked, scientists suggested that the amount of folding on the brain’s surface was the marker of a brilliant brain. The more convolutions on the surface, the smarter the individual. Other scientists identified specific fissures that they deemed inferior, as they were supposedly found more often in apes and women. These lines of research would be used to justify racial and gender stereotypes and give rise to the practice of eugenics in the first half of the 20th century.

The peer review process and established statistical methods ensure that today’s science is more legitimate than it was in centuries past. But neuroimaging has allowed us to probe the living brain to a degree heretofore unimagined. With it, scientists amass enormous amounts of data that strain our standard statistical techniques and challenge our ability to distinguish between profound, universal discoveries and those idiosyncratic to our subject sample or functionally irrelevant. We still don’t know whether ‘bigger is better’ nor understand the source or functional consequences of individual differences in the size and shape of brain regions. Certainly we don’t know enough to look at a person’s brain and guess with accuracy how smart they are, how good they are, or, yes, even how many friends they have.

Just look at this graph from the Nature Neuroscience paper plotting amygdala volume on the horizontal axis and social network size on the vertical axis:

The figure above shows each subject as a black dot (for younger participants) or a gray triangle (for older ones). The diagonal line shows a mathematical correlation between amygdala volume and social network size, but look at how many dots and triangles lie away from the line. For the same amygdala volume (say, 3 cubic mm), there are dots that lie far above the line and others that lie far below it. No one looking at this figure can say that amygdala size determines one’s sociability. Perhaps it plays some small role, sure. But we are not slaves to our amygdala volumes, just like we’re not slaves to our overall brain size, our fissural patterns or cerebral convolutions. Our abilities and thoughts do come from our brains, but we have to keep in mind that those brains are far more complex than we can fathom. Who you are can never be reduced to a list of measured volumes. It’s important that we remember that, and that we never return to those days of ‘mine’s bigger than yours.’

Her Nose Is Just For Show

April 5, 2009 By in Brains 1 Comment

No one knew my mother couldn’t smell until the day the septic tank was replaced. She was a curious girl and sat nearby to watch, while the rest of her family kept as far away as possible. Stench? she’d said. What stench?

My mother has no recollection of ever having smelled anything. She was either born without the sense or lost it at a very young age. Scientists call this ‘developmental anosmia.’ Thankfully, it’s a lot less incapacitating than losing other senses, such as sight or hearing. Mom’s lack of smell is good fodder for conversations (and blog entries), but other than the risk of missing a gas leak, she isn’t impaired. Since flavor depends mostly on smell, her ability to taste is probably restricted to the few types (e.g., salty, sweet) that the tongue detects. Still, she claims she gets a full spectrum of flavors, thank you very much, and she reminds me in stinky public bathrooms that her quirk is also an asset.

Although my mom is perfectly happy, it can be catastrophic when people lose their sense of smell later in life. This can happen for many reasons, including head trauma (wear your helmets!) or complications due to antibiotics. Even though most of us aren’t consciously aware of all the things we smell, odors are woven into all of our experiences and are powerfully tied to memory. People who have grown accustomed to the world’s symphony of smells are often severely affected by its loss. They can experience a profound absence in their lives. They can lose their appetite, their sex drive, even fall into depression.

I’ve tried to describe scent to my mom and she’s tried to imagine it, but always to no avail. Sometimes I wonder what it would be like to be left out of an invisible, inaudible, untouchable secret that everyone else shares. I’m pretty sure I’d be frustrated. And why should we cause anosmics frustration? Let’s give them a break and announce that olfaction is a hoax. While we’re at it, let’s say the same about telepathy, prophesy, and channeling the dead. I hear some people were born without those too.