developingintelligence | July 13, 2007Well, maybe it's "exotic" only to neuroscientists. Inhibitory structure in neocortex has usually been seen as fairly homogenous and simple, where the wide variety of inhibitory interneuron types was viewed as misleading: at bottom, they all perform a simple regulatory function of keeping only a few representations active at once. Thus, in contrast to subcortical regions, inhibitory networks in cortex were thought to involve mostly "vanilla" axon-to-dendrite connections in a semi-regular latticework of connections. However, in the current issue of Nature Neuroscience, Conners &…
developingintelligence | July 11, 2007For fans of scientific eye candy, the Nikon Small World competition is hard to beat - and this year, they've opened up the voting process to the public. Vote on your favorites but be careful - you can't revise your vote on a picture once it's cast!
developingintelligence | July 9, 2007Researchers at Duke University have recently invented a technique for improving the spatial resolution of magnetic resonance imaging (MRI) by a factor of nearly 100,000x. Whereas routine clinical MRI scans contain 3-dimensional pixels ("voxels") approximately 1mm x 1mm x 1mm, this new technique allows for voxels as small as 21.5 thousandths of a milimeter on each side.
This is fortunate for many mice, who in the future might no longer need to be sacrificed - but rather merely sedated - for precise neuroanatomical analysis. It is also fortunate for neuroscientists, as older histological…
developingintelligence | July 3, 2007The Neurophilosophy blog recently migrated to scienceblogs.com and the first post is an excellent edition of Encephalon. Check it out.
developingintelligence | June 28, 2007In 1948, Alan Turing wrote: "An unwillingness to admit the possibility that mankind can have any rivals in intellectual power occurs as much amongst intellectual people as amongst others: they have more to lose." Accordingly, comprehensive comparisons between the intellectual powers of great apes and humans are rare - perhaps because we feel safe in assuming that the human intellect is superior to that of other primates. But recent work suggests this assumption may not be entirely sound, as described below.
For example, a recent New Scientist article (via NeuroEthics) contains a provocative…
developingintelligence | June 27, 2007Though widely separated in terms of both neuroanatomical location and evolutionary development, there are surprising parallels between parietal cortex and the hippocampus:
- Both structures are important for spatial cognition, although parietal cortex is thought to maintain a "self-centered" map of the environment (i.e., where locations are represented relative to the direction of gaze) whereas hippocampus may maintain a "world-centered" or allocentric map (i.e., where locations are represented with respect to landmarks or surrounding geometry).
- Both structures are thought to represent…
developingintelligence | June 26, 2007The best from recent cognitive/brain blogs:
Suspect someone's lying to you? Ask for the story in reverse order. Psyblog also has some suggestions.
A sober look at mind-reading fMRI pattern classification techniques over at Mind Hacks.
Nabokovian reviews a new computational model of short term memory, using a recurrent network.
What's all the hooplah about embodied cognition? Why do some believe that bodies in particular are important for mind? MoaP explains a new spin on the classic mind-body "problem."
The Reasoner: a monthly digest of new research on research in cognitive science,…
developingintelligence | June 26, 2007Can you move a single matchstick to form a valid mathematical statement equation?
No sticks can be discarded, an isolated slanted stick cannot be interpreted as I (one), and a V (five) symbol must always be composed of two slanted sticks. UPDATE: The only valid symbols are Roman numerals and "+", "-" and "=". (Thanks Benjamin!) OK, now try this one:
[solutions here]
If you had trouble with that last puzzle, fear not - it means your frontal lobe is probably intact! Healthy adults are frequently outperformed by patients with frontal brain damage on that test, according to a 2005 study by…
developingintelligence | June 25, 2007Functional magnetic resonance imaging (fMRI) has captured the popular imagination since its introduction in the early 1990s, at least partially because of the stunningly beautiful images it generates. Although it has mostly used to identify brain regions involved in specific cognitive operations, new pattern classification techniques have been applied to fMRI data in what some have called "mind reading technology." These techniques go beyond simply showing which brain areas are more active than others during a particular task to reveal functional relationships among multiple brain areas,…
developingintelligence | June 21, 2007Though anatomically heterogenous, the human prefrontal cortex seems to perform a rather general function: it actively maintains context representations to guide and control behavior. What, then, is the reason for the anatomical diversity within this region of the brain?
Some theories suggest that prefrontal cortex (PFC) is organized to represent increasingly protracted contexts. According to this "temporal cascade" model, the most posterior regions of PFC are responsible for maintaining only the most current contextual information (e.g., "the doorbell rang") whereas progressively more…
developingintelligence | June 18, 2007How does your brain represent the feelings and thoughts that are a part of conscious experience? Even the simplest aspects of this question are still a matter of heated debate, reflecting science's continuing uncertainty about "the neural code." The fact is that we still don't have a clear picture of the ways in which neurons transmit information. Here's a quick guide to current theories, beginning with well-established theories and moving into ideas that are considered more theoretical.
The canonical model: firing rate
Clearly, neurons encode some information in the rate of their firing…
developingintelligence | June 13, 2007What was your 6th birthday party like?
If you successfully retrieved that memory, you may now be ever so slightly less able to remember your other childhood birthdays. A variety of behavioral evidence has shown that such "retrieval induced forgetting" of strongly competing memories is fundamental to memory retrieval. In a new article in Nature Neuroscience, Kuhl et al. provide neuroimaging evidence which ties retrieval-induced forgetting to activity in prefrontal cortex.
In the study, subjects studied a series of 240 word pairs, for example ATTIC-DUST, ATTIC-JUNK, or MOVIE-REEL. During…
developingintelligence | June 12, 2007Children have often been claimed to blend reality and fantasy, but according to some this is a wild exaggeration of the truth. For example, renowned child researchers have written that "even the very youngest children already are perfectly able to discriminate between the imaginary and the real" and certainly a lot of recent research tentatively supports that idea.
Still, it seems intuitively surprising that children should be so good at knowing the real from the imagined. Nearly everyone - even grown adults - has had the experience of saying (or thinking) something, and afterwards…
developingintelligence | June 11, 2007Symbols redirect attention - in some ways, that is their intended purpose - but this "reorienting" is a surprisingly literal and involuntary effect. Even when we know symbols are irrelevant to our current circumstances, they still influence our behavior.
A simple experiment demonstrates this nicely. Hommel et al. showed that letters appearing in unpredictable locations can be identified more quickly when their location is compatible with a preceeding symbol - even if those symbols are totally irrelevant to the task, and subjects are explicitly told to ignore them!
For example, a letter…
developingintelligence | June 8, 2007Recent highlights from the best in brain blogging:
"Brain training" games that are actually fun! Also check out the Lumosity blog. It seems like they understand the reward structure of good games.
Tonal similarities between music and language.
Genetic differences between speakers of tonal and non-tonal languages - critique at the excellent Language Log, including a response by the authors!
A cynic's guide to publishing scientific articles.
Reference management tools - but don't forget about CiteULike!
An architectural illusion?
A seminar at UVA on "robotic architecture" taught by Jason…
developingintelligence | June 7, 2007The neural processing of color, shape, and location appears to be widely separated in the brain, and yet our subjective experience of the world is highly coherent: we perceive colored shapes in particular locations. How do these distributed representation about visual features get brought or "bound" together to form an integrated percept?
Charles Gray suggests that there are actually many such binding problems - not only between visual features, but between other sensory modaliities as well as between perception and action. The brain may have evolved redundant mechanisms for solving this…
developingintelligence | June 6, 2007Some people experience an intermingling of the senses, known as synaesthesia, in which certain shapes become combined or "bound with" certain colors, or that certain colors are strongly associated with certain sounds. Of course, in healthy normal adults, color and shape become bound together only when visible shapes really are visibly colored - a process which is itself still a mystery of neuroscience. Yet similar mechanisms may be involved in both these kinds of "binding," but are merely more active in synaesthetes than in normal adults.
Based on Patient RM, we know that binding between…
developingintelligence | June 5, 2007How do you know what's where? Cognitive psychologists believe this requires "binding" - the ability to associate certain colors or shapes with each other and with certain locations in space, giving rise to a coherent perception of the world. It turns out that at least one unlucky person lacks this ability we often take for granted: the patient is known as RM, as reviewed by Lyn Robertson in this article on binding.
RM suffered two strokes, damaging both sides of his occipito-parietal cortex (see the image above). This region of the brain is known to be important for spatial computations;…
developingintelligence | June 4, 2007Suppose that one day your computer's hard drive stops working, but everything else about the machine is fine. Your friend has an identical computer in which the hard drive works fine, but the keyboard suddenly stopped working. Based on this "double dissociation" between the two different problems, can you safely assume that the "hard drive system" and the "keyboard system" rely on distinct underlying mechanisms?
For years, cognitive neuropsychologists have felt safe in making equivalent assumptions about brain damage. If one type of damage leads to difficulty on task A, but not task B, and…
developingintelligence | May 31, 2007Imagination allows us to escape our current time, place, or perspective in favor of an alternative context, whether that may be fanciful or mundane. So imagination is a mechanism for specifying and maintaining a context that differs from our more immediate and stimulus-driven experiences or contexts (at least, that is what I mean by "imagination"). According to Buckner & Carroll, this kind of "self-projection" from one context to another is the essential function that underpins the involvement of the prefrontal & medial temporal lobe (MTL) circuit in a variety of tasks, including…