Wednesday, December 19, 2007

Prof Little Helper

Ever need a little pick me up? I certainly do, and in fact, I’m sitting here drinking a cup of coffee as I write. In the wake of the steroids scandal in baseball and the increasing prevalence of drugs in the classroom (e.g. for ADD), an important debate is brewing on the role of pharmaceuticals in our daily life. A recent short article in Nature by Barbara Sahakian and Sharon Morein-Zamir outlines several issues related to the increasing use of stimulants to improve memory and alertness. The most striking point is that when we talk about taking a pill to achieve a cognitive benefit, it seems somehow different from drinking a cup of espresso. Interesting…

At any rate, this article is worth checking out because it calls attention to the blurry line between ‘cheating’ and taking a reasonable step to ensure maximum cognitive capacity. Clearly defining this line is critical as the next generation of school children comes of age in an era of widespread standardized testing: who can afford to fall a little behind or go at their own pace anymore?

Tuesday, December 18, 2007

CCNS faculty blog article on Scientific American

Scientific American runs an interesting blog called Mind Matters. It contains news and comments on neuroscience and psychology, with many entries being written by researchers in the field. The most recent entry on mirror neurons was written by CCNS director, Greg Hickok. Click here to check it out!

Friday, December 14, 2007

Congratulations, Kevin!

Congratulations to Dr. Kevin Smith, PhD for successfully defending his thesis "Is there an auditory "where" stream?" Great work!

Thursday, December 6, 2007

Interesting upcoming meeting on vision and memory


Sponsored by the American Psychological Association, Tufts University, and the Charles River Association for Memory
Dates: Thurs, May 29 - Sat, May 31, 2008
Location: Tufts University in Medford, MA

March 31, 2008: Deadline for early registration

How can people interact appropriately with and understand the world they see around them? Research suggests that prior knowledge about the world influences visual perception at both conscious and non-conscious levels. Emerging research on the neural basis of visual knowledge has begun to synthesize ideas from vision and learning and memory fields.
A group of twelve speakers has been carefully selected from the fields of Cognitive Neuroscience, Cognitive Psychology, Neurobiology, and Computational Modeling to discuss vision and memory, two important fields of Psychology that have proceeded largely in parallel. The goal of the conference is to enable interactions among cognitive psychologists, cognitive neuroscientists, and computational modelers who study the neural basis of vision and memory in humans and animals and who develop theories of visual knowledge through modeling. This conference will serve to facilitate not only the cross-pollination of ideas among scientists in each field but also to promote the emergence of a new field of visual knowledge that incorporates key ideas from these established research domains. For more information about this conference, and to register, please go to

Wednesday, December 5, 2007

Modularity of perception

Well over 100 years ago, scientists realized that damage to specific brain regions resulted in specific behavioral deficits. For example, damage to left frontal cortex is often associated with impaired language abilities. Observations of this kind led to the hypothesis that each chunk of cortex performs a specific task (often referred to as the ‘modularity’ hypothesis). In contrast, others suggested that different regions of the cortex are not specialized at all – that all regions participate in all aspects of cognition. Time has taught us that both of these extreme views are probably incorrect. We would quickly run out of space in our head if we dedicated a chunk of cortex to each task that we needed to perform. On the other hand, given the knowledge that damage to certain brain regions leads to very specific behavioral deficits, we must acknowledge that some specialization occurs.

How do we reconcile these two points of view? Recently, we investigated the issue of modularity using functional magnetic resonance imaging (or ‘fMRI’), a method that allows us to indirectly measure neural activity in humans (see article linked below). We focused on visual information processing, since we know quite a bit about the parts of the brain that are responsible for sight. Light comes into the eye, where it is converted into a series of electrical impulses by the retina (a process called ‘transduction’). These electrical impulses are then passed from neuron to neuron until they reach a region of cortex at the very back of the head that is referred to as V1. In V1, neurons respond to simple features in the environment, such as the orientation of edges and different colors. Neurons in V1 then pass along information to other visual areas for further processing. There are actually more than 30 visual areas that are involved in the process of analyzing visual inputs, and each one seems to contribute some unique bit of information to support perception. For example, area V4 – which is a few steps up the hierarchy from V1 – registers information about simple shapes, area MT registers the direction of moving objects, and some later regions register the identity of objects (such as faces).

On the surface, this functional specialization seems to support the ‘modular’ account of brain organization; however, no single visual area can support perception without working in concert with other areas. To give an extreme example, suppose the visual system has a module that only processes information about color. Now, suppose someone suffered damage to their eyes and could no longer transduce light coming into their retina. Obviously, this person wouldn’t be able to perceive colors, even though the color module was perfectly intact. Thus, functionally specialized brain regions cannot operate in isolation; some regions convert light into neural activity, some supply information about edge orientations, some about color, some about motion, and so on. Eventually this information is combined to create a coherent perceptual representation of the surrounding environment.

Even though no single area in isolation can give rise to perception, all areas are clearly not created equal. For example, in our study we examined brain activity in area MT while people watched videos of moving objects. Obviously, the ability of MT neurons to respond to motion depends on input provided by the eyes and by earlier visual areas. However, our experiment found that decisions about the perceived direction of motion are based primarily on the activity of MT neurons, even though activity in other areas is necessary to achieve the final overall percept. According to this account, modularity arises primarily when we need to make a judgment about some attribute of our environment. If we need to know about motion, we query the activity of neurons in MT, if we need to know about color, we might query the activity of neurons in V4, and so on. This viewpoint suggests that most cognitive operations rely on neural activity in a series of distinct cortical areas; however, the ultimate output of the process may be largely mediated by a single specialized area of the brain. One important future challenge will be to determine how more complex cognitive operations (beyond judging the direction of a moving object) are carried out and represented in cortex, and if the same organizational principles apply.


Monday, December 3, 2007

Left-Brain/Right-Brain: Wrong-Minded

There’s no shortage of left-brain/right-brain propaganda in pop culture. Browse the shelves at your local bookstore and you’ll find titles like Daniel Pink’s A Whole New Mind: Why Right-Brainers Will Rule the Future; peruse the booming educational toy market and you’ll find products like Brainy Baby’s “Left Brain” and “Right Brain” DVDs; or just open your ears to the ramblings of a motivational speaker or the chit chat of the office break room, and you’re likely hear some reference to left- and right-brain tendencies. In fact, a quick Google search turns up tens of thousands of documents touting the concept’s usefulness for everything from improving elementary school education or business management strategies, to understanding biblical symbolism, or why men are, and I quote, “beer-guzzling, TV-glued, [and] sex-driven.” You can even test your own left-brain/right-brain tendencies with a multitude of online personality tests. But don’t waste your clicks: if you tend to focus on artistic/holistic/spatial aspects of things you will be labeled “right-brained,” whereas if you lean towards logical/detail-oriented/sequential features, you are “left-brained.” Given its pervasiveness, you may be surprised to learn that most cognitive neuroscientists – scientists who study the relation between mind and brain – cringe when they hear popular references to left- versus right-brain function. To us, hearing someone say, “let’s learn to think with our right hemispheres…” is about as stimulating as fingernails on a chalkboard.

But, you say, isn’t it true that the brain is divided into two hemispheres? Yes it is. And isn’t it the case that the two sides are not identical in function? Yes, of course. Then what’s the problem with all this left-brain/right-brain stuff? Well, let me illustrate by example. Suppose I told you I could read your personality strengths and weaknesses – your self esteem, cautiousness, wit, secretiveness, destructiveness, and so on – simply by measuring the bumps and indentations on your skull. Perhaps you’d be interested in me examining your fiancĂ©e (or wish I had before you tied the knot), but more likely you’d think I was blowing smoke. And you’d be right. What I’ve described, in fact, is the 19th century doctrine of phrenology, which held that different brain areas controlled different personality traits, which could be more or less developed. A well-developed trait would command more neural bulk and therefore press on the skull to produce a measurable bump on the head; vise versa for under-developed traits. As ridiculous as it sounds today, phrenology was all the rage in 19th century popular culture, even making its way into political, management, and yes, marriage decisions.

What’s interesting, though, is that while the application of phrenology was seriously misguided, the underlying science was quite legitimate, even accurate in important respects. Indeed, just replace self-esteem, cautiousness, and wit, with motor control, speech, and memory and suddenly phrenology doesn’t seem so ridiculous (well except for that bump-on-the-head thing, but that’s not the core of the theory). In fact, that is precisely what many scientists of the time did with the idea: they ran with the fundamental concept, and ditched the personality trait lunacy.

So what does phrenology have to do with the current left-brain/right-brain mentality? In short, everything. Just like phrenology, the left-right craze is based on a fundamental scientific observation, namely that the two hemispheres are not identical in function, and just like phrenology, the concept has been seriously overblown and misapplied. The fact is, with few exceptions, just about any function or ability you can imagine involves a host of coordinated brain circuits in both hemispheres. The two sides may make somewhat different contributions to these abilities, but these differences generally pale in comparison to differences in function we see between networks within the hemispheres, such as those networks that support visual recognition versus those that enable language comprehension.

The parallels between popular left-brain/right brain dichotomies and phrenology run even deeper, though, as both concepts are based on a more fundamental misconception about brain organization, namely that complex functions are carried out by circumscribed islands of brain tissue. Look at just about any map of brain function and you will find tidy parcellations, like cuts of beef, with labels such as “language,” “memory,” “vision,” and “thought.” But this drastically oversimplifies the picture. For example, there is no “language area.” Instead our ability to use language is supported by a coordinated and widely distributed network of circuits spanning many regions in both hemispheres. These circuits may be individually specialized in function, to be sure, but it is the integrated action of the network that gives rise to our capacity for language. Furthermore, some of these circuits are not slaves to a linguistic taskmaster, but participate in other abilities as well. The same holds true of other functions.

So to say that the left-brain does one thing, and the right-brain does another, is a throw-back to phrenology (and a clumsy one at that!), that fails to recognize the more dynamic, interactive, network-based organization of brain function. So get with the network. Left-brain/right-brain is so 19th century!