Here’s an exchange of emails between PL and MC on a recently published paper (Balleine et al., 2007). Email 1 (from PL): Have a look at this introductory paragraph from a recent (Aug 2007) J Neurosci article by Balleine, Delgado and Hikosaka. What do they mean by “cognition” here? The Role of the Dorsal Striatum …
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In the dark confines behind our eyes lies flesh full of mysterious patterns, constituting our hopes, desires, knowledge, and everything else fundamental to who we are. Since at least the time of Hippocrates we have wondered about the nature of this flesh and its functions. Finally, after thousands of years of wondering we are now …
In 1992 Rizzolatti and his colleagues found a special kind of neuron in the premotor cortex of monkeys (Di Pellegrino et al., 1992). These neurons, which respond to perceiving an action whether it’s performed by the observed monkey or a different monkey (or person) it’s watching, are called mirror neurons Many neuroscientists, such as V. …
Hippocampus is involved in feature binding for novel stimuli (McClelland, McNaughton, & O'Reilly – 1995, Knight – 1996, Hasselmo – 2001, Ranganath & D'Esposito – 2001) It was demonstrated by McClelland et al.that, based on its role in episodic memory encoding, hippocampus can learn fast arbitrary association. This was in contrast to neocortex, which they …
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This image is not of a neuron. This image is of the other universe; the one outside our heads. It depicts the “evolution of the matter distribution in a cubic region of the Universe over 2 billion light-years”, as computed by the Millennium Simulation. (Click the image above for a better view.) The next image, …
This post is the culmination of a month-long chronicling of the major brain computation insights of all time. Some important insights were certainly left out, so feel free to add comments with your favorites. Below you will find all 26 insights listed with links to their entries. At the end is the summary of the …
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26) Some complex object categories, such as faces, have dedicated areas of cortex for processing them, but are also represented in a distributed fashion (Kanwisher – 1997, Haxby – 2001) Early in her career Nancy Kanwisher used functional MRI (fMRI) to seek modules for perceptual and semantic processing. She was fortunate enough to discover what …
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25) The dopamine system implements a reward prediction error algorithm (Schultz – 1996, Sutton – 1988) It used to be that the main thing anyone "knew" about the dopamine system was that it is important for motor control. Parkinson's disease, which visibly manifests itself as motor tremors, is caused by disruption of the dopamine …
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Shelley Batts’s Retrospectacle neuroscience blog recently got hit with a legal threat from journal publisher Wiley for posting some graphs from a recently published article. This request amounts to underhanded legal intimidation as using these graphs clearly falls under fair use. Shelley had clearly cited the source of the graph and accurately reported the results. …
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24) Cognitive control processes are distributed within a network of distinct regions (Goldman-Rakic – 1988, Posner – 1990, Wager & Smith 2004, Cole & Schneider – 2007) Researchers investigating eye movements and attention recorded from different parts of the primate brain and found several regions showing very similar neural activity. Goldman-Rakic proposed the existence of …
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23) Motor cortex is organized by movement direction (Schwartz & Georgopoulos – 1986, Schwartz – 2001) Penfield had shown that motor cortex is organized in a somatotopic map. However, it was unclear how individual neurons are organized. What does each neuron’s activity represent? The final location of a movement, or the direction of that movement? …
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22) Recurrent connectivity in neural networks can elicit learning and reproduction of temporal sequences (Jordan – 1986, Elman – 1990, Schneider – 1991) Powerful learning algorithms such as Hebbian learning, self-organizing maps, and backpropagation of error illustrated how categorization and stimulus-response mapping might be learned in the brain. However, it remained unclear how sequences and …
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21) Parallel and distributed processing across many neuron-like units can lead to complex behaviors (Rumelhart & McClelland – 1986, O'Reilly – 1996) Pitts & McCullochprovided amazing insight into how brain computations take place. However, their two-layer perceptrons were limited. For instance, they could not implement the logic gate XOR (i.e., 'one but not both'). An …
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20) Spike-timing dependent plasticity: Getting the brain from correlation to causation (Levy – 1983, Sakmann – 1994, Bi & Poo – 1998, Dan – 2002) Hebb's original proposal was worded as such: "When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, …
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19) Neural networks can self-organize via competition (Grossberg – 1978, Kohonen – 1981) Hubel and Wiesel's work with the development of cortical columns (see previous post) hinted at it, but it wasn't until Grossberg and Kohonen built computational architectures explicitly exploring competition that its importance was made clear. Grossberg was the first to illustrate the …
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