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December 4, 2011

This Proves We're Obsessed with Shiny Things


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´┐Ż??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
Posted by      Christopher R. at 10:37 PM MST
displaying most recent comments (47 ommitted) | Comments (50)
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December 1, 2011

Seeing With Your Mind.


When asked to imagine a particular object the mind seems to conjure the image instantly and you can observe it's many features with your mind's eye. Given that we all do this dozens of times a day it seems like a fairly boring and menial occurrence. However if you stop to think of the mental processes that underlay this phenomena you'll see how complex and important it is.

To first test the manner in which mental images are formed participants were shown an empty grid with a lower case letter beneath it. They were asked to imagine the corresponding uppercase letter in the grid as quickly as possible and state whether the letter would cover a particular block in the grid. As the letters became more complex (containing more segments) the response time increased. This finding led the researchers to believe that an image was not formed all at once, but rather as individual parts. (the letter F should take longer to recall because you must recall three parts as opposed to an L which contains only two parts). It also appears as if the parts were imaged in almost the same order in all cases. This is based off the fact that when the subjects were asked to draw individual letters they were imaged in the same sequence at least 75% of the time.

These findings were further supported by auxiliary evidence of the brain forming patterns. For example ------ is viewed as a straight line, not six dashes. Similarly XXX XXX is viewed as two groups not six X's as is XXXooo. Thus the brain is predisposed to organizing things as parts or "perceptual units." Given this it seems likely that the brain stores the letter F by its three individual parts rather than as a whole, and when the letter is recalled it is imaged a part at a time based off previously stored perceptual units.

Why is this the case? Why not simply remember something as a whole rather than by its parts? The answer comes via the limitations of the brain.

Previous research has shown that it is more difficult to hold onto a mental image while you are paying attention to actual visual stimulation. This would seem to say that some of the cortices involved in visual sensory input are implicated in mental imagery. To test why the things are organized by parts the researchers look at the processing of visual stimuli.

The two primary visual cortices are located in the inferior temporal lobe and the parietal lobe. Ablations in monkeys of the inferior temporal lobe causes the monkey difficulty in discriminating against patterns and shapes but have no difficulties in object location. The reverse is true in animals with ablations of the parietal lobe indicating that each lobe has a different functional relevance in visual processing. Thus the observation of "what" and "where" are processed separately.

This explains why we image things sequentially. The shape of a part is stored separately from it's location relative to other parts. For example an F is composed of vertical bar connected on top and in the middle to two horizontal bars. Given that 94% of the participants drew an F by drawing the vertical line first then top and bottom shows that there are parts prerequisite to other parts and thus must be imaged one part at a time.

This division of objects into parts has great importance. It is why we are able to recognize letters in different fonts. Rather than memorizing how an F looks in every form and being confused upon seeing a new font we merely have to know the parts of an F and how they relate to each other. This can be further extrapolated out away from the simplicity of letters. A person can assume many forms. We can stand, sit, curl in the fetal position and still we are able to recognize it as a person because we recognize the parts and how they are connected to one another, as opposed to knowing exactly how a person looks when they are curled.

This division relieves us of having to know much more specific information thus freeing up brain power so we can say, know how to write a blog.

Aspects of a Cognitive Neuroscience of Mental Imagery. Kosslyn et al. Science Journal.
http://wjh-www.harvard.edu/~kwn/Kosslyn_pdfs/1988Kosslyn_Science240_Aspects.pdf
Posted by      Zach I. at 4:22 PM MST
displaying most recent comments (1 ommitted) | Comments (4)
  Zach Irell  says:
Yeah I was wondering the same thing...they don't mention it at all in the paper most likely because they don't have a good answer. I think that there is definitely merit in that answer but from an evolutionary stand point it makes more sense for us to encode things in the way presented by these researchers. The letters are a very simplistic way for them to explain this and thats why we can call it into question but I think the results and direction of the paper point to things on a much larger and more complicated scale.
Posted on Sun, 4 Dec 2011 4:51 PM MST by Zach I.
  Christina Uhlir  says:
Did the paper get into templates and expectations? By templates I'm referring to mental representations of objects, people, scenes that act as a prototype that influences a person's perceptual experience (e.g. drawing from memory a letter and comparing it to the one you see in front of you) and based on that, the expectation a person has about the stimulus, and problematic interactions that could result.
Posted on Sun, 4 Dec 2011 5:04 PM MST by Christina U.
  Zach Irell  says:
This paper refers to how mental representation of objects, people and scenes are stored and how we recall them.
Posted on Thu, 8 Dec 2011 8:42 PM MST by Zach I.

Neocortex: Why We are Better


The neocortex is the outer layer of the cerebral hemispheres, where in humans, is believed to be involved in higher functions such as language, conscious thought, sensory perceptions, etc. There has been a high volume of interest and debate among developmental neurobiologists regarding the molecular mechanisms/molecules involved in differentiation and development of the neocortex. But to start with, the question is, why specifically this region of the brain?

The neocortex is not known to be present throughout the animal kingdom, but is presumed to be specific to mammals. For example, we, humans, are able to perform particular functions and have a higher order of thinking due to the mechanisms/processes of the neocortex. Therefore, the unknown entities and development of the neocortex is a highly talked about subject within this field because it can help explain the evolution of human behavior and the known generates high interest as many researchers seek answers about the development of mankind.

Therefore, within the past 20 years, there has been significant progress in identifying certain patterning of the neocortex through state-of-the-art molecular approaches, however, we are still very far from knowing the complete truth. For example, we now know that the anterior-posterior orientation has a genetic impact that if altered, can lead to diseases such as smooth brain syndrome. In this case it is the alterations of the concentration gradients of two molecules, DCX anteriorly and LIS1 posteriorly. Additionally, there is now pertinent evidence of genetic patterning that is symmetric between the two hemispheres, that if altered, can also lead to severe phenotypes. Another concept at large debate is whether the differentiation and development of the neocortex is more dependent on intrinsic or extrinsic mechanisms, in which informs our understanding on the developmental plasticity phenomena, critiquing the importance of critical and sensitive periods. In other words, how much is the regionalization of areas in the neocortex affected by varying the levels of essential transcription factors?

Besides the uses of molecular techniques, Chen and his colleagues are investigating these questions through a combination of twin studies and structural MRI to demonstrate the relative contributions of genetic and environmental factors in regionalization of the cerebral cortex. Therefore, they have concluded that although "genetic factors may have a boisterous influence in the establishment of regionalization of the cortex, functional areas do not seem to be influenced by the same factors," implementing that those environmental factors can also play a significant role in neuro-development.

With the newly employed combination of these analytical studies and ultimate hype on the development of the neocortex, this marks an exciting new chapter on the study of human brain development, where we can hopefully determine the genetic and environmental factors that determine the higher order functions of human/mammalian brain. Furthermore, with this marked data and more advanced research on the human brain development to come, we may one day find more genetic or environmental patterning of the brain that can lead to cures of diseases that are defined as incurable today.

Schlagger, B. "Mapping Genetic Influences On Cortical Regionalization." Neuron. Volume 74, Issue 4. Pg. 499-501. 17 November 2011.

http://www.sciencedirect.com/science/article/pii/S0896627311009597

Sarah Ha
Posted by      Sarah H. at 11:01 AM MST
  Christina Uhlir  says:
Do you know how new this field of study is?
Posted on Sun, 4 Dec 2011 4:09 PM MST by Christina U.

October 23, 2011

True or False: Emotions and Electrons Are Alike (Answer: true)


Remember that one time your girlfriend or boyfriend got ketchup on their nose while eating French fries and you thought it was hilarious, but immediately afterwards you felt guilty because they glared at you and growled for a napkin?

There is a word for that: ambivalence. The word ambivalence means that you feel two contradictory emotions (hilarity and guilty) simultaneously. Look a little more closely at the word ambivalence and you can probably guess what electrons and emotions have in common: valences. Emotional valences, like valence electrons, are shown outwardly on a persons face and they either attract (positive valence) or repel (negative valence) the person at which they are directed.

Many studies, since the advent of the fMRI, have examined the underlying circuitry involved in the expression and perception of emotion, especially negative valence emotions such as anger, sadness, and fear. The paper I analyzed is no exception to this rule: researchers from Kings College London, University College London, and the University of Z├╝rich worked together to a) ascertain the circuitry that underlies the processing of emotionally negative facial expressions, and b) determine whether or not the amygdala is involved in the conscious processing of emotive faces. Basically, they wanted to know if our first response to facial expressions is to think or react.

In the study, a pool of 40 subjects (selected based on a range of nonspecific qualities) were shown a set of 60 faces and a corresponding number of fixation crosses (an image of a white screen on which a + is superimposed), while in an fMRI. Each of the 60 faces displayed either a neutral expression or a negative expression (anger, fear, or sadness) and the subjects used a clicker to indicate whether the face did or did not show an emotion. For each face, the response time and accuracy was recorded and was used in concert with the data provided by the fMRI images. In addition to the tests performed using the fMRI, a battery of statistical tests corrected for noise and anatomical dissimilarities among participants.

The findings are significant: the amygdala is not the only cranial structure that modulates facial processing. To be more specific, their results show that while the amygdala is involved in the processing of facial affect(Dima et al 1) there are also pathways to and from the fusiform gyrus, the inferior occipital gyrus, and the ventrolateral prefrontal cortex, which do not involve the amygdala. Most notably, anger was mediated by the inferior occipital gyrus and ventrolateral prefrontal cortex, not the amygdala.

What does all of that mean?

Basically, our brains have evolved for cognition for so long that we now respond to physical or emotional danger (anger in this case) in a cognitive fashion. We think before we react to a potentially harmful event.

Now think back for a second to your girlfriend or boyfriend with ketchup all over their nose. If this research holds, you will not immediately react and give them the napkin; you will, in fact, think about the potential harm that could come to you if you do not (minimal: they probably will not punch you), and the potential benefits you will reap if you do not (photographic evidence of the event). As far as I am concerned this decision is easy: memory is leaky; emotions are transient; but a picture lasts a lifetime.

What would you do?

Source: https://cuvpn.colorado.edu/content/31/40/,DanaInfo=www.jneurosci.org+14378.full.pdf+html?sid=20ba56d1-84f2-4fdb-b108-83aed6437270
Edited by      Christina U. at 2:03 PM MDT

August 1, 2011

Upgrading your brain: A critique of Transhumanism


Have you ever wanted to be smarter or have a better memory, say, in the middle of taking an exam? For most of us, these desires seem unrealistic and we accept that our mental abilities have set limits that can?t be changed. However, there are some people who believe in Transhumanism, a philosophy that advocates the use of technology to enhance mental ability. In Future Minds: Transhumanism, Cognitive Enhancement and the Nature of Persons, Susan Schneider, a philosopher at the University of Pennsylvania, discusses the bioethics of the Transhumanist position. In particular, she examines whether mental enhancement is desirable from the viewpoint of personal identity. She believes that given the possibility that radical enhancement of an individual could result in the creation of a new entity that is no longer the same person, enhancement would not be ethical.
The basic tenets of Transhumanism are laid out in the Transhumanist Declaration that was written by members of the World Transhumanist Association. The tenets include:
(1) Humanity will be radically changed by technology in the future. We foresee the
feasibility of redesigning the human condition, including such parameters as the
inevitability of aging, limitations on human and artificial intellects, unchosen psychology, suffering, and our confinement to the planet earth.
and
(4) Transhumanists advocate the moral right for those who so wish to use technology to
extend their mental and physical (including reproductive) capacities and to improve their control over their own lives. We seek personal growth beyond our current biological limitations.
Dr. Schneider believes that Transhumanism should be taken seriously given that many of the technologies that would allow for radical enhancement are in early development now. She provides a possible future scenario hoped for by many Transhumanists. In 2025, people become cyborgs by receiving eye implants connected to the internet and brain implants to improve memory. Life extension through nanotechnology becomes available by 2040. Human beings continue to modify themselves until they become posthumans by 2060. The Transhumanist Frequently Asked Questions by Nick Bostrom describes a posthuman as a being ?whose basic capacities so radically exceed those of present humans as to be no longer unambiguously human by our current standards?. In this scenario, there is no difference between radically modified human beings and super-intelligent artificial intelligences by 2600 other than origin.
Philosophers have long debated the nature of the person and find many of the scenarios envisioned by Transhumanist to be metaphysically problematic in regards to the continuity of identity. Dr. Schneider argues that the enhancements endorsed by Transhumanism could lead to undesirable results because someone who undergoes more and more mental enhancements would eventually cease to exist. In that light, radical mental enhancement would be unethical being a form of suicide. She then examines the viewpoint on this issue held by many Transhumanists, that of Patternism in which ?enhancements can alter the material substrate but must preserve your memories and your overall psychological configuration.? Several case studies are given which indicate that Transhumanists have a lot of work to do to show that identity can be preserved after mental enhancement.
This article is of interest because it raises the possibility that mental enhancement could be a form of suicide. However, the issue was discussed only in terms of philosophy and did not include much of our current understanding of the brain. Any future brain enhancements would arise from basic neuroscience research and debates of this nature must include specifics regarding the structure of the brain. Hopefully, this article will challenge neuroscientists to address issues regarding identity brought about by radical brain enhancement.
Posted by      David J. at 12:00 AM MDT

July 31, 2011

Is Altruism Really Selfless?


It has long been assumed that altruism is something that we humans posses that other animals don?t. That our capacity for empathy applies only to us because we have such an overdeveloped cortex capable of higher-level processing. However, what if this is not true? What if primates, our evolutionary predecessors also had this capacity? What does this mean about our sense of selflessness and morality? The ideas presented by Frans De Waal in his article Putting the Altruism Back into Altruism: The Evolution of Empathy could have larger societal implications than just an explanation for morality. The ideas in this article question religious ideas and bring us one step closer to primates by suggesting that empathy evolved from primates. Instead of thinking of our ideas of altruism and morality as being handed down to us from up above (like religious ideas claim) maybe we should think of them as being passed up from below.

Frans De Waal is the director of a primate research institute in Atlanta Georgia. He argues that his primates regularly display altruistic behavior and therefore there has to be some sort of mechanism in the brain that is already wired to create altruistic behavior or is in place to learn altruistic behavior. In a radio interview Dr. De Waal tells stories of chimpanzees sharing treats so that everyone in the pack gets a little. He also cites instances where children have fallen into gorilla enclosures and the female gorillas have comforted the children and brought them to areas where they could be rescued by zookeepers as empathetic behavior. In his article, De Waal introduces some cognitive models of empathy. He proposes the ?Perception Action Mechanism? where motor neurons in a subject mirror the state of an object. And the ?Russian Doll Model? where empathy is a result of our higher-level cognition that uses a hard-wired basis to create empathy. Frans De Waal argues that being altruistic could have had evolutionary advantages that caused the trait to be selected for. A simple explanation would be if a primate was part of a pack and they hurt other members they would be ostracized and die without reproducing. But those who were good and able to work as a unit as opposed to as an individual would be kept under the protection of the pack. The mechanisms suggested above are the biological mechanism by which these traits are passed on evolutionarily.

De Waals points are intriguing but what really intrigues me is the social implications this article has. First of all, it is one more example of how similar we are to primates. The larger implication is that not only are we more similar, but we are more similar in a behavioral aspect that we humans had previously thought was part of our higher-level cognition: we thought empathy and altruistic thoughts were too complex for primates. Along with this implication comes a fear. If in fact there is a specific mechanism in the brain that controls altruistic behaviors what could happen if we were able to identify it? People could be tested to see if this area was underdeveloped, or abnormal in some way that would make them a hazard to society. Could we start condemning people to horrible, immoral acts before they happen based on their brain makeup? And, if we could, would this be a moral thing to do?

De Waal, Frans B.M. "Putting the Altruism Back into Altruism: The Evolution of Empathy." Annual Review of Psychology 59.1 (2008): 279-300. PubMed. Web. 31 July 2011. .

http://www.radiolab.org/2007/aug/13/
Posted by      Eileen E. at 11:15 PM MDT




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