Wednesday, September 30, 2009

Bye bye modular, hello cognit!

What is a cognit you ask? It's a basic unit of memory or knowledge defined by pattern of connections between a network of neurons associated by experience.

Termed by Fuster in 2006, the construct was created to solve the problematic yet popular view that the human brain is made up of discrete cortical domains dedicated exclusively to visual discrimination, language, spatial attention, face recognition, motor programming, memory retrieval, and working memory.

Although the modular modeling of the brain has utterly failed due to a lack of conclusive evidence, many neuroscientists continue to maintain this antiquated view... but why? Put quite simply, there was nothing better. However, thanks to Fuster, a new paradigm is emerging...

Monday, September 28, 2009

Why primate eyes prefer the color black




A recent study by Yeh, Xing, and Shapley over at The Center for Neural Science, New York University made a fascinating discovery about the primary visual cortex of the macaque monkey and it's preference for black over white stimuli similar to that of humans. Here's a snippet from their abstract.

Tuesday, September 22, 2009

Why middle-agers shouldn't join the army

Enlisting in the army is a significant life-changing decision, especially for someone who's middle-aged. Apparently there's an age cap of 42 for active duty. The reasoning behind this seemingly arbitrary number is that it allow for a 20-year military career before retirement. However, perhaps they should look toward a younger cutoff point in light of a recent study investigating the effects of sleep deprivation on arousal levels of middle-aged rats. But before we continue with this line of argument, lets define what being middle-aged really means.

Friday, September 18, 2009

Observation of tool use activates specific brain area only in humans

How'd those Frosted Flakes manage to get so high up in that cabinet? Can't...reach. Aha! Stool! Argh...still no dice. Darn these short arms. Oh oh! Broom! Almost got it...almost...almost...::crash:: NOOO!!! Game Over.

The discovery that a species other than human has the ability to use tools has, quite frankly, lost its novelty. Just look at the New Caledonian crow. If trained properly, it can utilize up to three different tools sequentially to reach for a target food reward (Wimpenny et. al, 2009). It does this by first picking up a stick-like tool with its beak. It then uses this tool to retrieve a second tool which is then used to retrieve a third tool. Finally, the third tool is used to successfully retrieve the food (sadly, I couldn't even do it using two).

Thursday, September 17, 2009

How your emotional state affects how you hear speech

I found an interesting study by Wang et. al investigating how the current emotional state that we find ourselves in modulates the auditory response of speech early in the sensory processing stream at the cortical level. Here's their abstract.

Monday, September 14, 2009

Coffee on the brain, spatial memory impairment, and how the immune system may help

I'm constantly on the lookout for new research findings further substantiating sleep's significant effects on memory...perhaps in an attempt to finally convince myself that continuously misplacing my keys is NOT a normal part of young adulthood...and that 5 hours of shut-eye just isn't cutting it anymore (note to self: resist late night treks to Starbucks).

Coffee-drinking women on the other hand have an 18% lower chance of having visual and spatial memory declines according to a 2007 study by Ritchie et. al. "No relation was found between caffeine intake and cognitive decline in men"...NOT FAIR!

a link on How to Overcome a Starbucks Addiction

Anyway...a recent study by Girardeau et al. found online at Nature Neuroscience once again confirms sleep's important function on memory consolidation. They found that suppressing sharp wave-ripple (SPW-R) complexes in the hippocampus-entorhinal cortex of rats during post-training rest and sleep significantly impaired spatial memory. (I'd bet that we'd see similar effects by suppressing slow-wave sleep spindles in the thalamus as well).

Saturday, September 12, 2009

Destabilizing old memories with novel information

What if one day we could disrupt unwanted consolidated memories like those of old traumatic experiences or even unforgettable heartbreaks and replace them with novel and more pleasant ones? Sounds like a tagline from the 2004 Oscar-winning film Eternal Sunshine of the Spotless Mind doesn't it?

Published in this month's issue of Learning & Memory, a study by Winters, Tucci, and DaCosta-Furtado over at the University of Guelph, Canada has managed to bring us one step closer to making this seemingly far-fetched idea a reality. They had rats explore sample objects and some time later injected them with either an NMDA receptor antagonist known as MK-801 or a control saline solution before reactivating the object memory.

Wednesday, September 9, 2009

Is inhibition a measure of free will?

Reading Alwyn Scott's "Stairway to the Mind" I came across an interesting tidbit of information pointing out that human's have a greater percentage of inhibitory neurons compared to other animals (human 75% rabbit 31%). For some unknown reason this made me think about the tricky construct of free will and the question of whether free will could be better measured not by what we chose to do, but by what we chose not to do. In other words, could free will be measured by a capacity to inhibit certain thoughts and behaviors.

Tuesday, September 8, 2009

Bullying boss disturbing your sleep?

Its not uncommon that we're forced to work/put up with a disgruntled boss at one point or another. Not surprisingly, the relationship between an employee and their boss is the best predictor for job satisfaction according to a 2006 survey conducted by Accountemps, a Menlo Park, California-based specialized staffing service for temporary accounting, finance, and bookkeeping professionals. Moreover, the relationship you have with your boss may not only determine your overall job satisfaction, but also how well you sleep.

In a study by Niedhammer et. al published in the latest edition of SLEEP they investigated the association between a bullying boss and experienced sleep disturbance. Here is a snippet of their abstract:

Saturday, September 5, 2009

Erasing phobias early in life

The model of fear extinction originated from the Pavlovian classical conditioning paradigm in the early 1900s. Defined as a reduction in a conditioned fear response following a non reinforced exposure to a feared conditioned stimulus, fear extinction is known to involve the amygdala and medial prefrontal cortex (mPFC).

It's also a frequently striven-for goal in cognitive behavioral therapy during the treatment of various phobias including arachibutyrophobia; the fear of peanut butter sticking to the roof of the mouth, or barophobia; the fear of gravity.

Unfortunately, extinguished fear responses sometimes reappear with the passage of time (spontaneous recovery), through a shift of context (renewal), or by unsignaled presentations of the unconditioned stimulus (reinstatement). However, the likelihood of these events happening after a few intense sessions of fear exposure may differ significantly depending on the age of the patient according to a new study published in this weeks Journal of Neuroscience.

Wednesday, September 2, 2009

The neural correlates of lucid dreaming

I've always had a deep fascination for lucid dreaming and only a handful of times have I been fortunate enough to experience such a wondrous and relatively rare state of consciousness. In one instance I decided to meditate and that blissful experience has no doubt left an indelible memory. So what's really going on in the brain during a lucid dream?

In a recent study Voss and colleagues over at Bonn University in collaboration with Hobson at Harvard Medical School decided to investigate the electrophysiological correlates of lucid dreaming. They attempted to train 20 undergraduate students in the art of lucid dreaming via pre-sleep autosuggestions over a four month period and were able to successfully train 6. These subjects then spent a few nights at a sleep lab hooked up to an EEG machine. Only half were able to experience lucid dreaming during their stay(now you can see how tough it actually is to induce a lucid dream).