Time: facts of physics and fibs of the brain?

Time is not what it seems...

Time is money, time is ticking, time is of the essence, time is many things. But what is time really?

Since Einstein's theories of special and general relativity, physicists understand time very differently from our every-day experience of time. 

I look at time the way physicists understand it with Emmanuel Olaiya, a particle physicist at the Rutherford Appleton Laboratory in Oxford in the UK.

I also speak with Craig Callender, a philosopher of physics at the the University of California in San Diego, about his quest to find why we are so hung up on a past, present and future with neatly flowing time between them.

You can find the feature on the FQXi website here. Just scroll down to the second feature. 

Music to Deaf Ears

Here is a link to the radio documentary I worked on over the summer.

What do deaf people hear? How far are scientists in their understanding of the auditory system? And how close are they in their ability to restore hearing? These are some of the questions the documentary ‘Music to Deaf Ears’ addresses. The piece aims to take the listener on a journey through the science, experience and sound of different types and gradations of hearing loss to allow listeners with normal hearing a glimpse into the world of a deaf person.

Freud's full circle?

While Freud's theories have had an enormous impact on psychiatry - psychoanalysis today still uses similar methods to the ones Freud developed in the beginning of the 20th century - they have long been engulfed in controversy. Freud's psychoanalytical thinking focused on the understanding of human behaviour by gaining access into the unconscious mind. In a typical session on Freud's sofa you might talk about your dreams and fantasies, letting your mind wander and speak without controlling your thoughts. Freud would listen to you, absorbing your thoughts and interpreting them, unravelling the unconscious conflicts that caused the symptoms for which you came to this session. Unveiling and subsequently dealing with these unconscious conflicts would cure the original symptoms of your mental instability.

One of the major criticisms of Freud lies in the lack of experimental scrutiny that surrounds his methods of baring the unconscious. Such lack of experimental evidence was, and still is, seen as unscientific. In the 1960s and 70s however, the idea of the presence of the unconscious re-emerged and became of particular interest for neuropsychologists who were trying to gain understanding in seemingly unconscious processes in split-brain patients and in disorders such as Alien Hand Syndrome. In split-brain patients, all the connecting fibres between the two sides of the brain were surgically cut to alleviate severe symptoms of epilepsy such that there are no direct routes for communication between the two halves of the brain any more. While this undoubtedly helped reduced the severity of symptoms, this procedure also had some other interesting effects. In a series of experiments that went on to gain him a Nobel Prize, Roger Sperry showed that each hemisphere could seemingly have simultaneous systems of volition. For instance, when he showed a split-brain patient a picture on the left side of a computer screen, which will be processed by the right side of the brain, the side that usually does not contain the language areas, they would tell him they had not seen anything. However, when he then asked them to select an object from several alternatives with their left hand (the one controlled by the right hemisphere), they would choose the object that was presented to them just a second ago even though they could not express why they had picked that exact object.

While complete sections of the corpus callosum tend no longer to be performed, similar bizarre “unconscious” desires also manifest themselves in patients with particular brain damage that affects this region. For instance, in patients with Alien Hand Syndrome one hand does something completely different and independent from the other. Perhaps the most famous example was Dr. Strangelove, who had to keep one hand in control with the other. Another compelling example is that of a woman who was determined to smoke a cigarette, but whenever her one hand had put the cigarette in her mouth, the other would grab it and throw it away.

In fact, as Emeritus Professor of Neuropsychology at Oxford Larry Weiskrantz has pointed out, a curious facet of many clinical syndromes caused by brain damage is that, while these patients may lose particular conscious faculties such as being able to recall past events or identify people by their faces, they still retain “unconscious” abilities to do exactly these things. A patient with prosopagnosia may not consciously be able to recognise faces as a result of damage to the temporal lobe, a region in the lower part of the brain particularly important for memory, but will still able to show changes in arousal when seeing someone familiar.

Today, with the ability to look inside the human brain while someone is ‘thinking’, we can observe the processes that go on inside, even the unconscious ones. With such brain imaging techniques neuroeconomists have already started to gain insight into unconscious thought processing by showing that when we make economic decisions, for instance buying something on eBay, we tend to depend much less on our conscious, rational deliberation and much more on subconscious gut feeling and emotion. Perhaps Professor John-Dylan Haynes at the Bernstein Center for Computational Neuroscience in Berlin made an even more intriguing discovery: he was able to predict, by looking at someone’s pattern of brain activity with functional neuroimaging, what a person is going to do and when they will do it nearly 10 seconds before he or she actually does it.

In an article published in Brain this week, Robin Carhart-Harris and Karl Friston argue that with the aid of these brain-imaging techniques, Freudian concepts might now be tested experimentally. Until recently, one of the most common ways to analyse brain imaging data was to directly compare networks of brain activation during a specific task to networks of activation during periods where the brain was assumed to be at rest. However, over the past ten years, research pioneered by Marcus Raichle started looking into what was actually going on in the brain during these periods of rest. Surprisingly, he and his colleagues noticed that the patterns of activity during rest periods were remarkably consistent, which lead him and other researchers to suggest the existence of a “default” network. According to Carhart-Harris and Friston this default network might represent intrinsic internal thought remarkably consistent with the unconscious thought processes in Freud’s later theories. Many of the key principles of Freud's theory they argue, such as 'the ego' (our conscious self) and 'the id' (our unconscious self), echo our current knowledge of how the brain functions on a global level (i.e. a different set of areas in the brain that is active during conscious processing from the set that is active during unconscious processing).

Could it be that, after his initial success and subsequent fall from grace, Freud has now come full circle? Appropriately, it turns out that even Freud himself had originally attempted a not dissimilar scientific approach in the Project of Scientific Psychology published in 1895. In his neurophysiological theory he suggested that the transfer of energy between neurons in the brain caused unconscious processes, but in the years to come he decided that neuronal processing as understood at the time seemed much too complex for such an interpretation. Instead, as a result of his analyses of dreams, he proposed that the unconscious was a result of highly condensed, symbolic thoughts – the primary processes – and the conscious a highly rational and logical way of thinking – the secondary processes. That neuroscientists are, consciously or unconsciously, currently returning to these ideas would likely have amused Freud.

This post also appeared on Cherwell's Matter Scientific

Brains powered by light

In the 1920s Felix the Cat had a brilliant idea and over his head a light bulb appeared; thus was created the signature of an epiphany. But recent advances in neuroscience leave you to wonder whether in the future a light bulb will be seen as the source of such inspiration rather than just the visual metaphor.

In the 1990s Peter Hegemann, a German biologist, discovered that green algae commonly found in ponds respond to light by wagging their tail, an interesting phenomenon given that they do not have eyes. When light photons hit the protein coils packed in the algae's cell membrane, a chemical reaction created a tiny gap, causing an ionic current to be produced and the algae's tail to wag. The protein that allowed this reaction is channelrhodopsin-2.

Some years later, American researchers started to wonder whether a similar mechanism could be used to control brain cells if certain neurons were made to behave somewhat like algae. By genetic engineering these scientists were able to do just this: not to make brain cells move but, using channelrhodopsin, to turn them on or off simply with light. The field of optogenetics was born.

What is so beautiful about this technique is that, by harnessing the cunning of viruses, it is possible to make the channelrhodopsin-encoding gene only be expressed in particular targeted neurons. And so far the results have been startling. Flies have been made to jump, mice made to walk in a certain direction, and both to remember events that never happened, all through the power of light. Optogenetics could therefore open the door to precise therapeutics in diseases such as Parkinson's disease and schizophrenia where presently only drugs or surgery can help, neural sledgehammers compared to the surgical scalpel enabled by light-controlled tools.

If its promise holds up, a bulb over someone’s head may someday be seen in a completely new light.

A long time ...

It has been a while since I last posted something on my blog thanks to a lovely long holiday in Turkey and a conference in the US, but I am back now and eager to do some more science writing.

I am going to start off gently by just pointing you to an interesting article I read in New Scientist this week about how in a scary situation it can feel like time slows down and the agony suffered seems to last for much longer [than it actually does]. Can it be that, in a scary situation, our brain works faster as a result of flight or fight? Or do we create memories about such events that are much more precise and therefore seem longer?

David Eagleman, a neuroscientist at Baylor College of Medicine in Houston, Texas, looked into the issue of the slowing of time by letting his colleagues experience a thirty meter free fall - a scary event over which you have no control. Afterwards he asked them to indicate how long they felt the fall had lasted for. All estimated times were about twice as long as the actual duration of the fall. I have uploaded a video to give you a sense of the experiment.

Proving that we perceive time slowing down in such scary situations is one thing, finding out its cause is a wholly different issue, one that is discussed in the New Scientist article 'Timewarp: How the brain creates the fourth dimension'. The mechanism that keeps track of time may well be important for the understanding of diseases where people experience delusion, such as schizophrenia.

David Eagleman's interest in time does not stop in the past and present. In his recent book SUM ('I am' in Latin) he deals with the more existential issues of the afterlive.

Neuroeconomics

Why are you reading this? Perhaps you found the Oxford Student in the JCR and are trying to take your mind off that all-too-nearby exam. Or maybe you spotted someone else reading it intently. Or, more likely, you picked it up as it was there, and, as we all know, anything free is good. It may surprise you that how we make such decisions is engaging some of the finest minds in three disciplines - economics, psychology and neuroscience – resulting in the invention of a new field of study: neuroeconomics.

Economists have long thought that we calmly weigh our decisions, thinking out all possible short- and long-term consequences, and always choose the option that will give the best results. Homo economicus drinks in moderation, never smokes, does the laundry and ironing, and never wakes up next to someone who only seemed attractive the night before, right?

That's where psychology – or common sense – comes in to point out that this is a terrific model of a saint/robot but might fall down for you or me. But psychologists themselves do not always seem attached to the real world, spending their time researching fractional differences in response times, for instance, when your hear the name of a dog if your arms are crossed – hardly everyday occurrences for us or homo economicus. And with neuroimaging, psychologists now demonstrate that certain parts of the brain (rather than say the liver) light up when hearing dog names if your arms are crossed too.

But, put these ingredients together and something exciting occurs. Economists and psychologists start to consider how real people might make irrational decisions. Neuroscientists look in the brain and find reasons why this may happen.

Here's one example. I shop on eBay, and am often willing to pay more than I ought. Why am I so irrational? Neuroeconomists show this is perfectly natural; in a social context we never want to lose out. No way someone else is going to run off with my shoes! And for this we can blame our brains: a small clump of cells which values the important things in life (food, drink, sex) tells us that winning against competitors is worth more than the shoes themselves.

But does wanting to win make us losers? Perhaps. As someone once said, “Success is getting what you want. Happiness is wanting what you get.” Neuroeconomists are well on the way to making our irrationality seem logical - even if our logic may forever remain irrational.