Man Who Inspired ‘Rain Man’ Dies At 58 (via NPR: All Things Considered)
Kim Peek may have been the world’s most famous savant. Dustin Hoffman portrayed a character based on Peek in the 1988 film Rain Man, which triggered hundreds of news stories and documentaries about the man with “islands of remarkable abilities in a sea of disabilities,” as scientists described him.
According to his father, Peek suffered a heart attack Saturday at his home in Murray, Utah. He was 58.
Kim Peek couldn’t operate a light switch or button his shirt. But his memory was so vast and deep and exact, he was compared to a computer. In fact, some called him “Kim-puter.”
Thinking Crickets: 'Cognitive' Processes Underlie Memory Recall In Crickets
Activation of two different kinds of neurons is necessary for appetitive and aversive memory recall in crickets. Researchers blocked octopaminergic (OA-ergic) and dopaminergic (DA-ergic) transmission and found that this resulted in the inability to recall pleasant and unpleasant memories, respectively…. (more @ ScienceDaily)
Phasic Firing Of Dopamine Neurons Is Key To Brain's Prediction Of Rewards
Although I don’t have much time to write about this now, this is closely related to my research interests. Here is a good micro-review of the field:
Researchers are one step closer to understanding the neurobiology that allows people to successfully learn motivated behaviors by associating environmental cues with rewarding outcomes, according to a study published in the Proceedings of the National Academy of Sciences….
Midbrain dopamine neurons fire in two characteristic modes, tonic and phasic, which are thought to modulate distinct aspects of behavior. When an unexpected reward is presented to an individual, midbrain dopamine neurons fire high frequency bursts of electrical activity. Those bursts of activity allow us to learn to associate the reward with cues in our environment, which may predict similar rewards in the future.
The burst of electrical spikes observed in dopamine neurons is facilitated by a protein called the NMDA receptor, which is expressed on the surface of the dopamine cells. In this study, researchers removed the NMDA receptor from the dopamine cells only, leaving the dopamine neurons unable to fire bursts. The cells would otherwise fire normally.
When researchers placed the mice in reward-based situations, they found that the mice without the NMDA receptor in their dopaminergic neurons could not learn tasks that required them to associate sensory cues with reward. Those same mice, however, were able to learn tasks that did not involve an association with rewards…. (more @ ScienceDaily)
Sleep: Spring Cleaning For The Brain?
If you’ve ever been sleep-deprived, you know the feeling that your brain is full of wool.
Now, a study published in the April 3 edition of the journal Science has molecular and structural evidence of that woolly feeling — proteins that build up in the brains of sleep-deprived fruit flies and drop to lower levels in the brains of the well-rested. The proteins are located in the synapses, those specialized parts of neurons that allow brain cells to communicate with other neurons.
Sleep researchers at the University of Wisconsin-Madison School of Medicine and Public Health believe it is more evidence for their theory of “synaptic homeostasis.” This is the idea that synapses grow stronger when we’re awake as we learn and adapt to an ever-changing the environment, that sleep refreshes the brain by bringing synapses back to a lower level of strength. This is important because larger synapses consume a lot of energy, occupy more space and require more supplies, including the proteins examined in this study.
Sleep — by allowing synaptic downscaling — saves energy, space and material, and clears away unnecessary “noise” from the previous day, the researchers believe. The fresh brain is then ready to learn again in the morning…. (continues @ ScienceDaily)
Sleep May Help Clear Brain For New Learning
A new theory about sleep’s benefits for the brain gets a boost from fruit flies in the journal Science. Researchers at Washington University School of Medicine in St. Louis found evidence that sleep, already recognized as a promoter of long-term memories, also helps clear room in the brain for new learning.
The critical question: How many synapses, or junctures where nerve cells communicate with each other, are modified by sleep? Neurologists believe creation of new synapses is one key way the brain encodes memories and learning, but this cannot continue unabated and may be where sleep comes in.
“There are a number of reasons why the brain can’t indefinitely add synapses, including the finite spatial constraints of the skull,” says senior author Paul Shaw, Ph.D., assistant professor of neurobiology at Washington University School of Medicine in St. Louis. “We were able to track the creation of new synapses in fruit flies during learning experiences, and to show that sleep pushed that number back down.”
Scientists don’t yet know how the synapses are eliminated. According to theory, only the less important connections are trimmed back, while connections encoding important memories are maintained…. (continued @ ScienceDaily)
Building a Brain on a Silicon Chip
An international team of scientists in Europe has created a silicon chip designed to function like a human brain. With 200,000 neurons linked up by 50 million synaptic connections, the chip is able to mimic the brain’s ability to learn more closely than any other machine.
(via Technology Review & BoingBoing)
This is a cool idea. However, it is one thing to build a chip, but another to somehow make it function like a part of a brain. How will they simulate complex patterns of neuronal firing? Furthemore, what “output” will they measure to determine if the silicon chip learns something successfully? As it is, we really don’t know how - in either an animal or human brain - patterns of neuronal activity correlate with learning and the formation of memories.
Forget It! A Biochemical Pathway For Blocking Your Worst Fears?
A receptor for glutamate, the most prominent neurotransmitter in the brain, plays a key role in the process of “unlearning,” report researchers at the Salk Institute for Biological Studies….
“Most studies focus on ‘learning,’ but the ‘unlearning’ process is probably just as important and much less understood,” says Stephen F. Heinemann, Ph.D., a professor in the Molecular Neurobiology Laboratory, who led the study. “Most people agree that failure to ‘unlearn’ is a hallmark of post-traumatic stress disorders and if we had a drug that affects this gene it could help soldiers coming back from the war to ‘unlearn’ their fear memories….”
Heinemann and his team were particularly interested in whether mGluR5, short for metabotropic glutamate receptor 5, which had been shown to be involved in several forms of behavioral learning, also plays a role in inhibitory learning. “Inhibitory learning is thought to be a parallel learning mechanism that requires the acquisition of new information as well as the suppression of previously acquired experiences to be able to adapt to novel situations or environments,” says Heinemann.
