Chris Chatham
developingintelligence
Posts by this author
March 27, 2007
"A good metaphor is something even the police should keep an eye on." - G.C. Lichtenberg
Although the brain-computer metaphor has served cognitive psychology well, research in cognitive neuroscience has revealed many important differences between brains and computers. Appreciating these…
March 23, 2007
The past continuously besets our ability to act flexibly in the future; habits grow strong, automaticity takes over and the mind wanders. Before you know it, you've forgotten to stop for milk on your regular commute, neglected to go to your dentist appointment, or merely "lost track" of what you…
March 22, 2007
Imagine you are invisible. Congratulations, you are now actually less likely to remember what you were doing a few minutes ago, and possibly a lot longer ago than that. At least, this is the basic finding from a 2002 article by Sahakyan & Kelley, who showed that when people are asked to…
March 21, 2007
In the new issue of Seed, Douglas Hofstadter talks about "strange loops" - his term for patterns of level-crossing feedback inside some medium (such as neurons) - and their role in consciousness. Likewise, Gerald Edelman has talked about how a "reentrant dynamic core" of neural activity could…
March 20, 2007
Imagine that you are about to pass to a teammate when he suddenly darts in another direction, in an attempt to get clear. With some difficulty, you will be able to modify your pass and correctly throw the ball to your teammate's new location. How is this process implemented in the brain? This…
March 19, 2007
Last week I discussed how central dopamine levels appear to correlate with how strongly actions are bound to particular visual features. I presented this as part of "the binding problem," but in fact the topic runs must deeper: cognitive neuroscience has yet to reveal the mechanisms by which the…
March 13, 2007
Some theories suggest that color and shape information - processed in different parts of the brain - must be integrated by attention in order to give rise to a coherent visual experience (in other words, attention is thought to solve the "binding problem"). Although that explanation is probably…
March 10, 2007
Recent highlights from the best in brain blogging:
Online experiments at the Harvard Visual Cognition Lab!
Less invasive brain-computer interfacing, for video games.
Brain-computer interface implants: videos.
A new weapon in the Israeli arsenal: the VIPER robot.
The current state of the art in…
March 9, 2007
"Simplicity is the ultimate sophistication." - Leonardo Da Vinci
"The aim of science is to seek the simplest explanation of complex facts. We are apt to fall into the error of thinking that the facts are simple because simplicity is the goal of our quest. The guiding motto in the life of every…
March 8, 2007
The infamous "binding problem" concerns how a coherent subjective experience of the world can emerge from the widely-distributed processing of individual object characteristics (for example, object identity and object spatial locations appear to be processed by independent neural systems). It is…
March 7, 2007
According to artificial neural network models that implement lateral inhibition, activation and inhibition are two sides of the same coin. These models often assume that patterns of activation compete with one another. In other words, in a given space of neural tissue (or "layer" in network terms…
March 6, 2007
Prospective memory involves remembering to remember - in other words, successfully executing a planned intention after having completed an unrelated task. If computational models of prospective memory (PM) are to be believed, then PM relies on many of the same mechanisms involved in a huge variety…
March 5, 2007
To what extent is music like language? Previously, I've reviewed how music and language share semantic characteristics, at least insofar as similar scalp electrical activity follows incongruent musical passages as follows incongruent words. But is it also possible that music has grammar, just…
March 1, 2007
Cognitive theories of "executive function" vary greatly in the number of distinct cognitive processes they propose to subserve the goal-directed coordination of behavior. Some theories suggest that strong active maintenance of information, and a way of "updating" the information that is maintained…
February 28, 2007
Yesterday I was invited to give this 15-minute presentation (PPT, PDF) to LearningRX about recent perspectives on working memory limitations, and their potential for informing cognitive training and enhancement programs.
In case you're curious, here's a list of references:
Baddeley, A. D. (1986)…
February 26, 2007
Memory, defined as "any lasting effect of experience," is an overly broad term. Those with damage to the hippocampus lose their long-term memory but retain the ability to maintain conversations (at least for short periods of time). But new perspectives on the nature of short-term or "working"…
February 24, 2007
The story of a patient who awoke after a 20-year coma, induced by traumatic brain injury.
Epidemic proportions of TBI in soldiers returning from Iraq: a new problem.
Second chance to live: a new blog written by a TBI survivor.
It is becoming clear that we have little idea of how the sleep…
February 22, 2007
Children are famously bad at remembering to do things - for example, taking out the trash. What exactly is the developmental trajectory of the ability to remember and execute planned actions (known as prospective memory)? Although the effects of traumatic brain injury and old age on prospective…
February 21, 2007
Findings in the laboratory do not always apply to the real-world - a myriad of factors can influence real-world phenomena, and scientists actively seek to eliminate many of them in their laboratories. But ecological validity can be particularly difficult to establish in cognitive science, where…
February 20, 2007
In the middle of the work day, you realize you'll need to stop at a store on your way home from work. Your ability to actually do so, hours later, relies on what some psychologists call "prospective memory." Although prospective memory is clearly important for human intelligence, very little is…
February 19, 2007
The distributions of reaction times are always positively skewed, which seems to reflect two independent processes: a normal gaussian distribution of reaction times, in addition to an exponentially-decaying distribution of a few very long trials. Measures of this reaction time (RT) variability…
February 16, 2007
How do the symptoms of ADHD relate to the circuitry underlying executive function and working memory? An in-press article at Neuropsychopharmacology investigates the roles of dopamine and norepinephrine in ADHD, with evidence from both behavioral and simulated experiments. This post will make…
February 15, 2007
Dopamine is probably the most studied neurotransmitter, and yet the neuroscience literature contains a huge variety of perspectives on its functional role. This post summarizes a systems-level perspective on the function of dopamine that has motivated several successful drug studies and informed…
February 14, 2007
In a 2006 Psychopharmacology article, Niv et al. suggest that while transient dopamine release is frequently modeled computationally (as encoding reward-prediction error, for example, or as gating information into working memory) the role of more constant dopamine release is not. In the…
February 13, 2007
Check out the latest issue of Encephalon at MindHacks - covering topics like sleep research, decision making, music perception, and the cognitive processing of time. Nice job Vaughan!
February 13, 2007
According to some perspectives, anterior cingulate cortex (ACC) may become activate in situations where the reward value of given representation or stimulus has decreased, resulting in more competition between representations. Activation of this region may help increase tonic norepinephrine,…
February 12, 2007
Whereas yesteryear's artificial neural networks models were focused on achieving basic biological plausibility, today's cutting edge networks are modeling cognitive phenomena at the level of neurotransmitters. In a great example of this development, McClure, Gilzenrat & Cohen have an article…
February 9, 2007
Khalil Gibran said that "music is the language of the spirit," but today many would claim it can convey only a general impression or mood. However, recent research has shown that the meaning of musical passages can be surprisingly specific. In their 2004 article, Koelsch et al. demonstrate that…
February 8, 2007
Intuitively, an adaptive information processing system should deal with unique or unusual information in a special way. For example, an unusual encounter might indicate that an organism's environment is changing, and by implication that there's a new potential for danger. Or novel information can…
February 7, 2007
Although "executive function" may seem like an elusive topic for study, in cognitive neuroscience it is largely approached simply as the ability to control one's own behavior in accord with some goal, despite interference from previous experiences. Central to many accounts of executive function is…