Blind sight: The next generation of sensory substitution technology

Conventional wisdom says that you see with your eyes. But new technology is changing the way we think about sensation and perception, showing that instead of relying on these orbs for vision, we instead really see using the activity in our brains.

My newest piece for Discover Magazine explores three amazing devices that are restoring sight to the blind, circumventing the malfunctioning sensory organs and tapping into the healthy neuro-circuitry underneath. High-tech computers in Google Glass-like devices are converting visual information into auditory and tactile stimuli, allowing the blind to see, drive, navigate, and mountain climb using their ears, fingertips, and even their tongues, the brain translating this information back to the visual cortex.

Check out the full piece here, including a video of one of the devices in action.

Spending more time in the dark could boost hearing in old age

Your brain can do amazing things, not least of which is change. Specifically, neurons can adapt and grow new connections to help compensate for a loss in function in other areas. This has been most dramatically shown in children who have an entire hemisphere of their brain removed, usually to treat extreme cases of epilepsy, the other side taking over so that they can still walk, talk and function normally. Another common example of this type of neural plasticity is the improvement of other senses, particularly hearing, after the loss of sight.

In my latest article for The Guardian, I review a study that reports improvements in hearing in mice that have been visually sensory deprived for a week — meaning they were locked in a darkened room. Amazingly, cells in a sensory relay-station part of the brain reorganized to strengthen their hearing after this temporary loss of sight, even in older mice, which were previously thought to be exempt from this ability. While it’s still early days, this finding opens up the possibility for less invasive ways to treat hearing loss in old age.

Check out the full piece here.

How a pregnant mother’s diet could change a child’s brain

Scientists have pursued every possible avenue to try to figure out why we keep getting fatter. They’ve explored our genes, our brains, our hormones and our gut bacteria, not to mention our fatty, sugary diets and sedentary lifestyles. Now, a recent study has come out blaming our expanding waistlines and poor health on our parents’ behaviors before we were born.

My newest article is up on The Atlantic, discussing recent research on the impact a mother’s diet has on her offspring’s health, affecting our brains and subsequently our bodies. This line of research isn’t new — other studies have shown links between a woman’s health during pregnancy and her child’s weight later in life — but this is one of the first to provide a potential explanation for this phenomenon by looking in the brain at some crucial hunger hormones.

However, you can’t blame all of your problems on your parents; what you eat still has a major impact on how these brain changes manifest:

Now, I’m all for shifting blame away from myself and onto my parents, but I feel that, like every possible explanation behind the obesity epidemic, this is only one piece of the puzzle. Genes undoubtedly play a role in body mass, fat percentage, and metabolism, but so does what you eat and how many calories you burn through physical activity…The problem of obesity, like so many health and social issues we face today, is that there isn’t just a single contributor to the problem. If there were, it would have been solved by now.

Check out the entire piece here.

Seeing left, smelling right

We’ve all heard about the “left-brain/right-brain” hype, which, to be honest, is really just a bunch of malarkey. Supposedly, a bigger right hemisphere means you’ll be a great artist, and a larger left indicates a penchant for science. If the dancer spins clockwise, you’re right-brained, while if you’re left-brained she twirls counter-clockwise.

Fortunately, all of these neural conspiracy theories have been largely debunked. However, the fact does remain that we do have two hemispheres that are connected but divided – a cortical “separate but equal,” if you will. And oftentimes, one of these hemispheres is larger than the other, the smaller being situated slightly behind. Now, again, this is not to say that the bigger hemisphere is better, simply that they are asymmetric, and presumably this asymmetry has evolved for a reason.

Researchers from University College London have investigated the purpose of this neural asymmetry on a much smaller scale using the zebrafish, a common animal model used for investigating basic but deceptively complex brain-related phenomena thanks to their simplified central nervous system. Published in the journal Current Biology, the researchers discovered that neuronal asymmetry lends itself towards enhanced processing of sensory information in the zebrafish, and that a symmetrical brain can result in an impairment of the processing of visual or olfactory stimuli.

The researchers focused on the habenula – an area located near the thalamaus that is a type of way station in the brain, processing sensory information. The habenula receives inputs from around the brain and helps to designate the appropriate neurochemical output for neurons further down the line. However, cells in the left and right habenula react differently to different types of stimuli, resulting in separate projections to other areas of the brain.

In the current study, cells in the right habenula were largely responsible for receiving odor information, while the left-sided neurons processed visual information. Very few neurons responded to both types of stimuli. These left and right neurons also had distinct outputs, the left heading to the dorsal, or top, interpeduncular nuclei (IPN), while the right had outputs to the ventral, or bottom, IPN. These ventral and dorsal IPN neurons subsequently had their own distinct outputs as well, meaning the entire operation of processing visual and olfactory information was distinct, divided between the two hemispheres.

The real test of any scientific phenomenon though, is what happens when you disrupt this process (scientists really just like to mess things up to see what will happen). Will the other hemisphere take over, or will that function be entirely lost?

To find out, the researchers “shocked” the fish with cold – meaning when the fish were still embryos, they exposed them to extreme cold with the hopes of disrupting their typical gene expression and thus their cell development. In fact, using cold shock was so successful, it resulted in a complete reversal of many of the fishes’ neurons, meaning that what was right was now left, and left was right. Not only did this lead to a switch in the processing of sensory information, but the entire assembly line from the habenula neurons on down was reversed, a mirrored reflection of the fishes’ normal cell functions. Light information was now processed on the right side, however, the projections to the IPN remained the same. So light processed on the right side projected to the dorsal IPN, whereas previously the dorsal IPN had been activated by the left habenula light response.

The final step was to find out what happens when asymmetry is completely lost, to ascertain whether there was a functional benefit to this lateralization (again, scientists really just like to mess with a perfectly good brain process). To do this, the researchers manipulated the fishes’ neurons so that the habenula cells were either all right or all left. That isn’t to say that all the neurons were located on either the left or the right side, but rather the cells acted like they were all “right” neurons or “left” neurons, receiving inputs and creating outputs from and to their respective sources.

This complete lateralization resulted in a loss of the opposite side’s function, meaning the “double-left” fish had exceptional vision but were unable to process odors, while the “double-right” fish were blind to the light but had a super-power sense of smell.

Finally, even fish that were raised in complete darkness still showed this laterality when it came to processing visual information, meaning that the brain’s left-right organization was dependent on gene expression, not the cells’ experience or exposure to light.

From this, the researchers concluded that it doesn’t actually matter which side the cells are on, so long as each type of cell and its connections are in place. But a loss of those neurons, even if others are in their place, leads to complete functional disruption. And really, this makes sense; it is not the location of the cell but its connections that truly matter, dictating its function.

Yet another instance of science proving cool stuff that, if we really thought about it, we already kind of figured to be true.

Also posted on Mind Read.

The White Stuff

Whether it goes in our mouths or up our noses, we’re drawn to the powdery chemical confectionaries that can both give us pleasure and cause us harm — The White Stuff

I’m very excited to announce a new project I’m launching today on Beacon Reader, The White Stuff, where I’ll be writing about our favorite vices: food and drugs. I’m trying to bring some sense into the ongoing debate about what we put into our bodies, and my goal is to provide unbiased research-based reporting on the latest science and policy news on addiction, nutrition and everything in between.

Beacon is a new kind of journalism platform that, instead of being financed with ads or commissions, lets you fund my work directly. In addition to my own writing, you’ll get access to exclusive content from all of the other amazing journalists on the site who write about politics, technology, global issues, sports and more.

However, I need help getting the project off the ground. In order for the project to launch, I need 25 people to subscribe in the next 14 days. If you like what you’ve read on Brain Study, please help with my new endeavor by subscribing and sharing my project page for The White Stuff (there’s even a snazzy promo video).

I’ll still be writing from time to time on Brain Study, but most of the action is going to be over on Beacon, so if you want to stay up-to-date, please subscribe!

Anxiety about certain things can be hereditary

It looks like we might be able to start putting the nature-nurture debate to bed. Epigenetics – the new hot-button research topic in both science and the media – is the ability of genes to be influenced by our experiences, altering our genetic make-up in real time. By changing the chemical signals that course through your brain and body, you can actually turn genes on or off, a process that can then influence your future actions. Thus, in some ways, epigenetics can be thought of as the bridge between nature and nurture—your behavior and environment affecting your biology, and vice versa.

I have an article in The Atlantic this week exploring epigenetics through a couple recent studies investigating inherited learning – where a parent’s experience alters their own genetic make-up, and this change is then passed on to their child. Admittedly, this all sounds a bit too much like Lamarckism, and scientists are quick to caution that the field is still in its infancy, so it’s hard to tell just how important this will be for our understanding of genes and behavior. But in the mean time, some of things we’re discovering about our parents’ unseen influence on us are pretty damn cool.

Check out the full Atlantic piece here.

Can synesthesia in autism lead to savantism?

I’ve got a new piece out on the Scientific American MIND blog network today on the fascinating link that’s been discovered between synesthesia – a “crossing of the senses” where one perceptual experience is tied to another, like experiencing sound and color together – and autism spectrum disorder.

Individuals with autism have significantly higher rates of synesthesia than the rest of the population, and the two are potentially linked by a unique way in which the brain is wired. White matter tracts that traverse our brains, connecting one area to another, are thought to be increased in both conditions. This results in an abnormal wiring of the brain that may lead in more close-range connections, but fewer long-distance ones. And it’s possible that these extra connections may also contribute to some of the extraordinary cognitive abilities seen in some autistic individuals with savant syndrome.

For more on the story, check out the full piece on here.