Five things it'd be nice if neuroscience could explain but can't yet

The problem with neuroscience (other than Congress expecting university faculty to do it as a hobby) is that, by and large, answers to the really fun questions remain but gross speculation. Sure, we have a pretty good handle on, say, the pharmacokinetics of the α_2B receptor, but that's not really the sort of thing that impresses the squares at some cocktail party. They want to know a Big Answer; the brain weirdnesses that have vexed the sages through the ages. That Socrates or Confucius didn't even know what an α_2B receptor was doesn't get you off the hook. They retain their dead famousness, and you continue to labor in your live obscurity.

It would be nice if we could get a big win for our side. What would a big win look like? Read on.

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We have finally knocked down that infernal 10% of your brain question (see the final word on the matter HERE). Still, there are other questions, pressing and real, that remain about This Waking Life. Phenomena that are easy to state and common to experience but when push comes to shove we neuroscientists are obliged to admit we yet have no firm explanation. That does not prevent gross speculation, which I shant chide but rather take as confirmation of just how fascinating these issues are to people. Nosce te ipsum the Oracle said (albeit in Greek not Latin). And it's always the bizarro nosces everyone wants to know.

As such, I have chosen a few brain issues that would be muy bueno if we could explain and described them below. Five, to be precise. Unravel any one of them, stalwart neuroscientist, and fame and fortune will be yours. Or at least the thanks of a grateful nation, which is pretty much all you can expect from the nation anymore as the part of the nation holding the purse strings ain't exactly forthcoming with the grant money these days. But I digress.

In no particular order, LabKitty gives you: Five things it'd be nice if neuroscience could explain but can't yet.

1. The Cocktail Party Problem

Since we began with a cocktail party problem, let us begin with the Cocktail Party Problem. It actually goes by that name in the literature, believe it or don't. Briefly: you are in a noisy room full of people all speaking at once. How does your brain focus on one conversation to follow?  In more formal language, we seek the mechanism of selective attention.

An explanation has been proposed for the CPP based on gamma oscillations*. At the cellular level, such an oscillation takes the form of repetitive activity in a large population of neurons. When recorded in the EEG, this activity is manifest as a little sine wave burst. Hence, "oscillation."

Pithy, overly-simplistic analogy: think of your brain as a tuning fork and the party conversation as bashing on it in different keys. You mentally tweak the tuning fork to respond most vigorously to the conversation of interest. The vibration of the fork is analogous to a gamma oscillation, repetitive neural population activity focusing your attention.

Plausible, perhaps. However, there are some weirdnesses in the gamma story. One that jumps to mind is a study by Walter Freeman (Berkeley), who conditioned rabbits using odors (present an odor -> get a treat) and recorded gamma oscillations in the olfactory cortex during the task. He found that once an odor became meaningful (i.e., associated with a reward) the presentation of the odor generated a recognizable pattern of gamma activity. But if Freeman trained a rabbit on an odor (say, banana) then trained it on a different odor (strawberry) then retrained it on banana again, the new representation of "banana" was different than the original one. Not exactly what you would expect to observe if the rabbit's internal monologue was along the lines of: Ah, yes. Banana, my old friend. We meet again.

Still, there is much more to gamma than I have let on in these few brief paragraphs. The interested might start with Erol Basar's review monograph, available HERE on Amazon.

* The name "gamma" follows the tradition of naming EEG rhythms after Greek letters; the letters alpha, beta, and delta were already taken to describe slower oscillations of about 10 Hz or less. Gamma is usually between 50–100 Hz, depending on the system and species.

2. What are dreams?

La petit mort, as the French call sleep*, has engaged natural philosophers since protohumans first realized they were doing it. A voluminous, mountainous, enormous, immense (my thesaurus app is running out of adjectives here) literature now exists on the neurophysiology of sleep, no aspect of it more intriguing than dreaming. Every armchair neuroscientist from Freud to Francis Crick has taken a swing at an explanation, sometimes with rather loopy results. Is it a manifestation of unconscious desires? Tapping of the Jungian subconscious? Messages from the future? Does dreaming provide hallucinogenic practice of motor programs as Michel Jovet proposed? Or does it guide brain development generally, as suggested by Howard Roffwarg? Perhaps the function is mere housecleaning, consolidation of short term into long term memory or the catabolism of waste products generated during the previous day of productive mental activity or blog writing.

Alas, these are but hints and allegations, incidents and accidents. We have come to understand many of the gears that turn under the process since the revolutionary sleep studies of the 1950s. Intrinsic circadian rhythms. The four stages of sleep and their cyclical pattern. The identification of REM sleep with dreaming. The role of serotonin centers in the brainstem and the suprachiasmatic nucleus in the hypothalamus. The burst firing of thalamic neurons that generates sleep spindles. We begin to understand how sleep but not why sleep. And the larger prize of dreams remains more elusive still.

*Oops. Apparently the little death is a French euphemism for orgasm. Man, those guys are in a whole 'nother world over there.

3. What is consciousness?

This question seems to mean something different to everyone, so let me recast it in a precise if somewhat pedestrian form. Sit in a dark room with your eyes closed. Press (gently!) on your eyelid. If you do this just the right way, you will see a light (flash, sparkle, spot, whatever). Yet, there is no light. You know there is no light. But you cannot not perceive the eye poking as light.

Who or what, exactly, is being "fooled" into seeing light? That is what I mean by "consciousness."

It's a question as old as forever. Famously, Descartes rode this one to fame. Cognito ergo sum most people remember, or some people remember. But fewer remember that Descartes believed the brain was just a vehicle the soul rode -- literally --  in the pineal gland. The main fiber tract that connects the pineal to the rest of the brain was named the habenula, from the Latin for "horse rein." Yep, Rene believed you sat on top of your brain and steered around this mortal coil like a rider on a horse. And that guy's famous.

Aside from the Stuart Gordon classic From Beyond, we neuroscientists don't incorporate much of Descartes' theory into our daily lives these days. Yet, with the waning of religion (thanks, Obama!) the onus was pressed upon us to explain just what the Hector Lonzo is going on. If the brain is not a vessel for the soul, then how does the whole business of being "you" work? How is it possible that squishy stuff generates this entity staring out from behind your glasses? Honest status: no clue.

4. Earworms

It's not pathology as pressing as epilepsy or stroke, nor one that has engaged the Great Philosophers, but every year on the first day of Intro to Neuroscience 101 someone usually asks about it. What is happening when a song gets stuck in my head? 

There's really not much more to say. Most people have experienced the quirk to some degree. Not to mention that, more often than not, whoever is at the helm of the internal jukebox invariably has a terrible taste in music. Nobody ever gets the Adagio or Neko Case stuck in their noggin. It's always Mama Said Knock You Up orTeen Autotune #5 with Breasts or the Meow Mix jingle. Perchance therein lies a clue.

It is tempting to conclude the syndrome is simply a more benign cousin of the seizure disorders, but we would then be guilty of the armchair speculation taken to task above. What we need is to stick a volunteer into an MRI, then have them get a song stuck in their head and identify the region(s) of the brain that are abnormally active. Lesion those regions stereotaxically and observe. Viola!  Nobel prize and/or incarceration.

Probably why this one is such a tough nut to crack.

5. Prime number fetishes

Location of primes in the first 10,000 numbers

Number five does not appear on the popular radar so much. Rather, it is a personal favorite ever since I read an account of it in Oliver Sacks' The Man who Mistook his Wife for a Hat. I cannot improve on his telling, so let me quote an excerpt. Here, Sacks recounts his experience visiting the state hospital where resident twins John and Michael had become something of a local media sensation because of their mental math prowess:

They were seated in a corner together, with a mysterious, secret smile on their faces, a smile I had never seen before, enjoying the strange pleasure and peace they now seemed to have. I crept up quietly, so as not to disturb them. They seemed to be locked in a singular, purely numerical, converse. John would say a number -- a six-figure number. Michael would catch the number, nod, smile and seem to savor it. Then he, in turn, would say another six-figure number, and now it was John who received, and appreciated it richly. They looked, at first, like two connoisseurs wine-tasting, sharing rare tastes, rare appreciations. I sat still, unseen by them, mesmerized, bewildered.

What were they doing? What on earth was going on? I could make nothing of it. It was perhaps a sort of game, but it had a gravity and an intensity, a sort of serene and meditative and almost holy intensity, which I had never seen in any ordinary game before, and which I certainly had never seen before in the usually agitated and distracted twins. I contented myself with noting down the numbers they uttered -- the numbers that manifestly gave them such delight, and which they contemplated, savored, shared, in communion.

As soon as I got home I pulled out tables of powers, factors, logarithms and primes -- mementos and relics of an odd, isolated period in my own childhood, when I too was something of a number brooder, a number see-er, and had a peculiar passion for numbers. I already had a hunch -- and now I confirmed it. All the numbers, the six-figure numbers, which the twins had exchanged were primes.

Sacks goes on to note that number fetishes are not unusual in cases of autism or mental retardation, and prime numbers frequently hold some privileged status in the inner workings of the unusual mind. Why? This one doesn't even have the beginnings of an explanation.

In the billions of neurons and trillions of synapses, the miles of connections and the combinatoric explosion of brain cells connected or not, what is it that possibly creates an undercurrent of prime numbers? And why is this framework only revealed in rare cases, often involving brain pathology?

Mark my words: understand this, and you will understand the brain.