Scientists now have a better understanding of how precise memories are formed thanks to research led by Prof. Jean-Claude Lacaille of the University of Montreal’s Department of Physiology. “In terms of human applications, these findings could help us to better understand memory impairments in neurodegenerative disorders like Alzheimer’s disease,” Lacaille said. The study looks at the cells in our brains, or neurons, and how they work together as a group to form memories.
Chemical receptors at neuron interconnections called synapses enable these cells to form electrical networks that encode memories, and neurons are classified into two groups according to the type of chemical they produce: excitatory, who produce chemicals that increase communication between neurons, and inhibitory, who have the opposite effect, decreasing communication. “Scientists knew that inhibitory cells enable us to refine our memories, to make them specific to a precise set of information,” Lacaille explained. “Our findings explain for the first time how this happens at the molecular and cell levels.”
Many studies have been undertaken on excitatory neurons, but very little research has been done on inhibitory neurons, partly because they are very difficult to study. The scientists found that a factor called “CREB” plays a key role in adjusting gene expression and the strength of synapses in inhibitory neurons. Proteins are biochemical compounds encoded in our genes that enable cells to perform their various functions, and new proteins are necessary for memory formation. “We were able to study how synapses of inhibitory neurons taken from rats are modified in the 24 hours following the formation of a memory,” Lacaille said. “In the laboratory, we simulated the formation of a new memory by using chemicals. We then measured the electrical activity within the network of cells. In cells where we had removed CREB, we saw that the strength of the electrical connections was much weaker. Conversely, when we increased the presence of CREB, the connections were stronger.”
This new understanding of the chemical functioning of the brain may one day lead to new treatments for disorders like Alzheimer’s, as researchers will be able to look at these synaptic mechanisms and design drugs that target the chemicals involved. “We knew that problems with synapse modifications are amongst the roots of the cognitive symptoms suffered by the victims of neurodegenerative diseases,” Lacaille said. “These findings shine light on the neurobiological basis of their memory problems. However, we are unfortunately many years away from developing new treatments from this information.”
Photo: Memory (1896). Olin Warner (completed by Herbert Adams). Bronze door at main entrance of the Library of Congress Thomas Jefferson Building, Washington DC.
New research from Université de Montréal and McGill University’s Montreal Neurological Institute and Douglas Mental Health Hospitals show that the brain initially reacts to different emotional stimuli in much the same way, with disgust, amusement and sexual arousal provoking the same areas.
Ten male subjects aged between 21 and 30 years were treated to a series of more than 120 short film excerpts selected by the researchers for their lack of potential to induce any significant emotional reaction. These excerpts, which were extracted from movies or documentaries, depicted various scenes of social interactions (e.g. gardening, renovation, etc…). By comparison, the males were then shown a series of 30 second long excerpts depicted scenes shown to elicit amusement (comedy), disgust (scenes of mutilation), or sexual arousal (explicit male-female interactions). The clips that were the most useful in arousing a reaction, as rated by the group, were then used in the experiment.
A different group of twenty young men watched the clips through googles while having their brain scanned by an MRI machine. The brain activity that the researchers were able to observe is shown below.
Authors Sherif Karama, Jorge Armony, and Mario Beauregard write that ”given that this network includes brain regions known from previous work to be intimately involved in homeostasis, arousal, appraisal, and attention, results could be speculated to suggest the existence of a set of areas meant to improve the way we deal with activating emotional stimuli as these are arguably the ones with the greatest potential of having an immediate impact on our lives.”
Image: Plos One. “All contrasts clearly show involvement of the frontal operculum, dorsolateral prefrontal cortex, premotor and motor cortices, temporo-occipital regions, and cerebellum.” doi:10.1371/journal.pone.0022343.g002
I just got back from a mega road trip from Montréal to San Diego (between my favourite and second-favourite North American cities, respectively). While I was away visiting Grizzlepuss and my other nephews and nieces, the embargo lifted on some awesome new neuroscience research that I promoted - click through for the full press release.
Researchers at uMontreal’s Rivière-des-Prairies Hospital have been looking at the brains of people with autism for a long time. By using brain scans, they discovered that their neurological functions are completely reorganized, which explains why some people with autism have special visual abilities.
Jane Hughes at the BBC explains it this way:
[The study] suggests that the brains of autistic people are organised differently from those of other people; the area at the back of the brain, which processes visual information, is more highly developed.
That leaves less brain capacity in areas which deal with decision-making and planning. That may be why people with autism can be better than others at carrying out some types of visual tasks. For example, some are able to draw highly accurate and detailed images from memory. However, they can find it difficult to interpret things like facial expressions.
The condition varies in severity, with some people functioning well, but others completely unable to take part in normal society.
The American Museum of Natural Science in New York City also picked up on the research, and provided this extraordinarily eloquent slide show to explain the findings.
Image: This image shows areas in the brain where autistics show more activity than non-autistics when processing visual information: “faces” in red, “objects” in green, and “words” in blue. Credit: Human Brain Mapping, Wiley-Blackwell Inc.