PLASTICITIES « Between matter and form, between experience and consciousness, the active plasticity of the world »
8.5K views | +0 today
Follow
PLASTICITIES  « Between matter and form, between experience and consciousness, the active plasticity of the world »
TRANSDISCIPLINARY NETWORK ON PLASTICITIES    /    RÉSEAU TRANSDISCIPLINAIRE SUR LES PLASTICITÉS  
Your new post is loading...
Your new post is loading...
Rescooped by Plasticities Sciences Arts from Neuroscience_topics
Scoop.it!

Autism as a disorder of prediction

Autism as a disorder of prediction | PLASTICITIES  « Between matter and form, between experience and consciousness, the active plasticity of the world » | Scoop.it

Autism is characterized by diverse behavioral traits. Guided by theoretical considerations and empirical data, this paper develops the hypothesis that many of autism's salient traits may be manifestations of an underlying impairment in predictive abilities. This impairment renders an otherwise orderly world to be experienced as a capriciously “magical” one. The hypothesis elucidates the information-processing roots of autism and, thereby, can aid the identification of neural structures likely to be differentially affected. Behavioral and neural measures of prediction might serve as early assays of predictive abilities in infants, and serve as useful tools in intervention design and in monitoring their effectiveness. The hypothesis also points to avenues for further research to determine molecular and circuit-level causal underpinnings of predictive impairments.(...) - by Sinha P et al., PNAS,  vol. 111 no. 42, 15220–15225, doi: 10.1073/pnas.1416797111


Via Julien Hering, PhD
No comment yet.
Rescooped by Plasticities Sciences Arts from Amazing Science
Scoop.it!

Older Brain Is Willing, but Too Full for New Memories

Older Brain Is Willing, but Too Full for New Memories | PLASTICITIES  « Between matter and form, between experience and consciousness, the active plasticity of the world » | Scoop.it
Studies in modified mice suggest that it is harder to make new long-term memories as we age because the brain is full of old ones that are hard to erase.

 

The N-methyl-d-aspartate receptor (NMDAR) is widely known to be the synaptic coincidence detector essential for controlling synaptic plasticity and gating memory formation . Together with the NR1 core subunit, the NR2A and NR2B subunits form the diheteromeric or triheteromeric complex of the NMDA receptor in the forebrain regions. Depending on ages or states of animals, dynamic changes in NR2A and NR2B can lead to the different mixture of NR1/NR2A, NR1/NR2B, and NR1/NR2A/NR2B receptors in the forebrain. There is a higher amount of NR2B expression in postnatal and juvenile brains, but NR2A gradually becomes more prevalent in adulthood and advanced ages.

 

Based on distinct biophysical properties of the NR2A and NR2B (such as longer channel opening duration with the NR2B subunit than the NR2A, etc.), it has been hypothesized that an increased NR2A:NR2B ratio in the sexually matured and/or aged brains may represent a major genetic factor underlying the age-dependent, gradual constraint on memory functions in comparison to that of juvenile or younger brains. However, it is difficult to test this NR2A:NR2B ratio hypothesis by directly comparing the young animals with the aged animals because there are significant differences in expression of many other genes between those two age groups. Moreover, the levels of NR2A or NR2B expression in the cortex and hippocampus can also be dynamically modulated by individual experiences (i.e. enriched environment, or social interactions).

 

A series of genetic studies have shown that global knockout of NR2A resulted in lesser CA1 long-term potentiation, a moderate deficiency in spatial reference memory and fear memory, and/or significant spatial working memory deficit. This suggests that the presence of NR2B in NR2A−/− mice largely preserves LTP and most long-term memories. On the other hand, genetic deletion of NR2B in the forebrain- or hippocampus-specific knockout of NR2B results in more profound memory deficits and impaired LTP. These experiments, by examining the extreme ends of the NR2A:NR2B ratio spectrum (without NR2A or NR2B), have provided fundamental insights into the roles of the pure NR2A- or NR2B-containing NMDA receptor population under the given test conditions.

 

The initial evidence for the concept that an increased NR2A:NR2B ratio may reduce synaptic plasticity and memory function in adulthood came from NR2B transgenic experiments. Research has shown that genetic overexpression of NR2B in the mouse forebrain can lead to larger hippocampal long-term potentiation (10–100 Hz range, without affecting LTD) and enhanced learning and memory function as tested in seven different memory tasks. Similar memory and LTP enhancement was also observed in NR2B overexpression transgenic rats, pointing to the conserved beneficial effects of NR2B in multiple animal species. Thus, these NR2B overexpression experiments, along with other studies, have provided important evidence that the increased NR2A:NR2B ratio can be detrimental to greater synaptic plasticity and memory function in the older brains.

 

In a recent study, scientists have directly tested this hypothesis and investigated the effects of increased NR2A:NR2B ratio in the adult mouse forebrain on synaptic plasticity and learning behaviors by producing CaMKII promoter-driven NR2A transgenic mice. They combined hippocampal slice electrophysiology and behavioral paradigms to investigate how such overexpression may alter synaptic plasticity and cognition, and showed that the high NR2A amount in the forebrain principal excitatory neurons can selectively affect long-term memory formation. But surprisingly, instead of the predicted smaller LTP in the CA1 region of the NR2A transgenic mice, the researchers found that NR2A overexpression selectively abolished 3–5 Hz frequency-induced LTD in the CA3-CA1 synapses without affecting 100 Hz LTP or 1 Hz LTD.

 

This results suggest a novel step by which long-term memory consolidation engages LTD-like process to sculpt, crystallize, and incorporate newly acquired information into long-term knowledge in the brain.


Via Dr. Stefan Gruenwald
No comment yet.
Rescooped by Plasticities Sciences Arts from Science News
Scoop.it!

A Meeting of Mind: Neuroscience, Art & the Creative Process

A Meeting of Mind: Neuroscience, Art & the Creative Process | PLASTICITIES  « Between matter and form, between experience and consciousness, the active plasticity of the world » | Scoop.it

New efforts are being made to reconcile neuroscience with the arts and humanities, a process which is throwing further light on the fact that our brain works in a very creative way simply viewing a piece of art.

http://www.scoop.it/t/science-news?tag=neuroscience

 


Via Sakis Koukouvis
No comment yet.
Rescooped by Plasticities Sciences Arts from Consciousness
Scoop.it!

UCLA Psychologists Report New Insights On Human Brain, Consciousness

UCLA Psychologists Report New Insights On Human Brain, Consciousness | PLASTICITIES  « Between matter and form, between experience and consciousness, the active plasticity of the world » | Scoop.it

UCLA psychologists have used brain-imaging techniques to study what happens to the human brain when it slips into unconsciousness. Their research, published Oct. 17 in the online journal PLOS Computational Biology, is an initial step toward developing a scientific definition of consciousness.

 

The psychologists analyzed the “network properties” of the subjects’ brains using a branch of mathematics known as graph theory, which is often used to study air-traffic patterns, information on the Internet and social groups, among other topics.

 

“It turns out that when we lose consciousness, the communication among areas of the brain becomes extremely inefficient, as if suddenly each area of the brain became very distant from every other, making it difficult for information to travel from one place to another,” Monti said.

The finding shows that consciousness does not “live” in a particular place in our brain but rather “arises from the mode in which billions of neurons communicate with one another,” he said.


Via ddrrnt
No comment yet.
Rescooped by Plasticities Sciences Arts from Neuroscience_topics
Scoop.it!

Very long-term memories may be stored in the pattern of holes in the perineuronal net

Very long-term memories may be stored in the pattern of holes in the perineuronal net | PLASTICITIES  « Between matter and form, between experience and consciousness, the active plasticity of the world » | Scoop.it

A hypothesis and the experiments to test it propose that very long-term memories, such as fear conditioning, are stored as the pattern of holes in the perineuronal net (PNN), a specialized ECM that envelops mature neurons and restricts synapse formation. The 3D intertwining of PNN and synapses would be imaged by serial-section EM. Lifetimes of PNN vs. intrasynaptic components would be compared with pulse-chase 15N labeling in mice and 14C content in human cadaver brains. Genetically encoded indicators and antineoepitope antibodies should improve spatial and temporal resolution of the in vivo activity of proteases that locally erode PNN. Further techniques suggested include genetic KOs, better pharmacological inhibitors, and a genetically encoded snapshot reporter, which will capture the pattern of activity throughout a large ensemble of neurons at a time precisely defined by the triggering illumination, drive expression of effector genes to mark those cells, and allow selective excitation, inhibition, or ablation to test their functional importance. The snapshot reporter should enable more precise inhibition or potentiation of PNN erosion to compare with behavioral consequences. Finally, biosynthesis of PNN components and proteases would be imaged. (...) - By Roger Y. Tsien, PNAS July 23, 2013 vol. 110 no. 3012456-12461


Via Julien Hering, PhD
No comment yet.