NRSC 2100 Blog

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How does a predator within 4 seconds of scanning an environment map it, memorize it, and sort out all unnecessary information from the info needed to be able to survive? Many theories have to do with the difference between top down and bottom up visual processing. Top down processing refers to the slower, executive cognition behind vision while bottom up is fast and not consciously driven and heavily influenced by environmental cues. Those environmental cues have been studied as to their effect and also as to what exactly grants them salience, or the property that allows the stimulus to stand out against its backdrop. While many studies have already been done studying the effect of salience on such things as saccade movements in the eyes to fixation periods to mapping brain location, little to no experiments have been done trying to illuminate salience and its relationship to memory.
A simple task was devised consisting of having 12 participants focus on a scene for a brief period of time. The view is then removed from the participants and they are subjected to a wait period. Once that time is completed the participants are asked to recall the position of several figures in the scene to test their memory. They varied the difficulty of the scenes and the salience of the objects to see if there was any correlation between the two, and as it turns out there was indeed. The salience of the object was directly correlated with the performance of the participants meaning they were more successful at recalling the objects exhibiting greater degrees salience than they were recalling inconsequential items. Furthermore, they tested this with varying degrees of difficulty and found that the more difficult the recollection task was, the greater the positive effect of salience had on the performance of the participants. While one could argue that they perhaps were drawn to those items and they simply focused on those items more than the others thus increasing the chances of memorization, they mapped and timed their eye movements to measure any fixation times on the items and found no difference in the fixation times between the salient objects and the non-salient objects meaning that they spent the same amount of time memorizing each object.
To summarize the findings, they showed that human�??s ability to recall objects within a certain space is positively dependent upon the salience of the object, and it is not due to any differences in memorization periods. A positive correlation between the increasing difficulty of the task and the positive effect of salience on memorization suggests that perhaps the brain may use salience to identify objects of value and omit objects deemed unimportant when the brain is forced to compromise.
They did make sure to mention another study with conflicting results. The study opted for a test involving people to assess whether a certain object was in a scene. They authors asserted that the difference in the findings could be attributed to the inherent difference in the tests, as one dealt with object identification and another with object location and spatial memory. They conclude that salience of an object and the effect it has on memory needs to be studied on a brain system to brain system basis, analyzing which systems are involved and what that would then imply.
This study provides more insight into the evolution of sight and how vision has been used and fine tuned throughout evolution. Recognition of the salience of an object is conserved throughout most species and clearly plays a pivotal role in the utility of vision as a whole. The ability to quickly asses an environment for all the information essential for survival is something that if without many animals would fall prey much more often due to lack of attention. This often taken-for-granted aspect of our vision that we are mostly unaware of is something that most certainly needs to be studied further and fully understood.
Original Article: http://www.jneurosci.org/content/29/25/8016.full

Thursday, Friday, and Saturday night... I know what you're thinking. No class till Monday, no work, what a great night to get ahead on studying and up to date with all the problems in the world. However, I must point out this plan is not the first thing that pops into everyone else's mind (at least those outside the world of the poor soul who is reading this neuroscience blog). Much of western society is based around the beverage/drug/poison we've come to know as alcohol. It has come to the attention of neuroscientist that our race is not the only one that takes pleasure in consuming firewater. It turns out some researchers were playing with the old 160 proof lab ethanol when they came upon an astounding discovery.

It all started when one turned to the other and croaked, "I'm drunkk frog haha." The other slurred back, "weelll thenn, gooood thing I'm not a fly huh?" That's when it hit them. "Eureka!" piped the first. "Oh my god!" yelled the second. "Let's" get the flies wasted!" the second hollered back. They quickly spun off their lab stools and bustled for the fly room stumbling and tripping the whole way. When they got to the room they immediately grabbed the first beaker of flies, ripped out the cork and filled it full of the powerful booze, instantly killing all the flies inside. Once they realized the horrendous massacre they had just committed in front of all the hundreds of thousands of other flies in the room their drunken smiles slipped off. The beaker was placed on the counter as the two somber scientists held each other with silent tears streaming down their cheeks. Then one started laughing; irritated, the other muttered, "How can you laugh at a time like this? We just killed them, in front of their families... drowned them, squashed them like flies... "Look, that one's drunk," the other researcher pointed at a fly that was clearly not adhering to the standard sober drosophila flight pattern. They watched the fly for nearly two hours, they sat on the fly room floor entranced by the fly's drunken escapades. Then as its flight pattern began to return to normal it headed back to the beaker full of booze, and began gulping down, without a thought to the dead brothers, sisters, cousins and children floating on top. Gleeful laughter burst from the researchers as they cheersed and began taking large quaffs of their own. Quickly forgetting their bloody hands they then began pulling the corks of the other beakers, filling up petri dishes with ethanol, and pipetting small volumes of ethanol in for the larvae--so no one was left out. They spent the whole night at the lab with their new found drinking buddies and had a gay old time. A few days later after their handover was gone they decided to write a paper.

It was determined drosophila liked the inebriation caused by excessive consumption of ethanol. Like us, the flies were experiencing their pleasure through the activation of the dopamine pathway. Activating this pathway induced LTP in the flies. Looking further into the flies' neural circuitry the researchers determined the rewarding memories the flies experienced (or the lack of memory if they got too plastered from not getting enough sugar before) were localized, accessed and retrieved with a distinct set of neurons in the mushroom body. With the vast number of flies they got drunk the researchers' found some flies didn't come back to drink. The experimenters were obviously offended and quickly squashed them. However, they didn't stop there; they proceeded to analyze the DNA so they could breed out the bad gene and make sure no other flies would be lame. They found mutations in scabrous were responsible. They commonly call it the party pooper gene around the lab. "This gene encodes a fibrinogen-related peptide that regulates Notch signaling, disrupted the formation of memories for ethanol reward" (Kaun, 2011). The experimenters have been thought to have had a little bit too much fun drinking with the flies, but they have felt the public pressure. Now they're looking into how this research will help their own species and we will undoubtedly be hearing more from them soon.

Hope you enjoyed the read, sincerely Charlie Stewart

"A Drosophila model for alcohol reward"
Karla R Kaun, Reza Azanchi, Zaw Maung, Jay Hirsh & Ulrike Heberlein
Nature Neuroscience April 17th 2011

It appears as though we're going back to the future, again, through the help of neuroscience. This time around, there is no time travel involved...just brain waves. A group of German researchers have recently used drivers' brain signals to assist in automated car braking, resulting in quicker reaction times and a potential solution to prevent thousands upon thousands of car accidents each year caused by human error.

The braking system is actually quite simple: through an EEG connected to the scalp and with modern traffic sensors equipped in most luxury cars today, the scientists could detect a driver's intention to break nearly 130 milliseconds faster than they would manually braking themselves. This 130-millisecond difference is phenomenal in that it nearly circumvents all the 'thinking' a human has to do to perform the same braking action.

Crunching Numbers: At 100 km/h, this means that the automated braking system would spare the average driver approximately 12 feet in space compared to manual breaking, which is just about the size of a standard compact vehicle. The twelve feet of distance gained by the driver could be the difference between a minor fender bender and a fatal car crash, or even no car accident at all.

But, this arising technology certainly isn't foolproof. For this reason, the scientists at Berlin Institute for Technology added a second component to their braking system: EMG. Instead of relying on brain signals for car braking, they also use human leg muscles for the same purpose. The scientists measure leg muscle tension associated with braking and are able to sense when a person is going to brake before their legs even reach the brake pedal. Thus, adding another safety dynamic to the overall automatic braking system.

Unfortunately, this technology is still new and undergoing initial testing. Most trials are conducted through simulations and computer programs and haven't been integrated into real working vehicles.

According to the lead author of the study: "We are now considering to test the system online in a real car however if such a technology would ever enter a commercial product, it would certainly be used to complement other assistive technology to avoid the consequences of false alarms that could be both annoying and dangerous." I think it is important to note that under no circumstances are the scientists trying to replace human function, they are only trying to strengthen and improve it.

The thought of automated braking and driving is actually kind of frightening. Where should we draw the line in terms of technology replacing what we do as humans? Are there any caveats that we simply can't predict with this automated driving technology?

As far as I'm concerned, I would love for this technology to gain funding and respect in the scientific community. But until we actually know what we're doing with it, I'd prefer for it to remain on computer simulations until I know I can trust my life or other people's lives with it.

Sources: http://iopscience.iop.org/1741-2552/8/5/056001/ (Full Text PDF Available on Website)