Researchers show that memories reside in specific brain cells
From MIT News - Simply activating a tiny number of neurons can conjure an entire memory:
Our fond or fearful memories — that first kiss or a bump in the night — leave memory traces that we may conjure up in the remembrance of things past, complete with time, place and all the sensations of the experience. Neuroscientists call these traces memory engrams.
But are engrams conceptual, or are they a physical network of neurons in the brain? In a new MIT study, researchers used optogenetics to show that memories really do reside in very specific brain cells, and that simply activating a tiny fraction of brain cells can recall an entire memory — explaining, for example, how Marcel Proust could recapitulate his childhood from the aroma of a once-beloved madeleine cookie.
“We demonstrate that behavior based on high-level cognition, such as the expression of a specific memory, can be generated in a mammal by highly specific physical activation of a specific small subpopulation of brain cells, in this case by light,” says Susumu Tonegawa, the Picower Professor of Biology and Neuroscience at MIT and lead author of the study reported online today in the journal Nature. “This is the rigorously designed 21st-century test of Canadian neurosurgeon Wilder Penfield’s early-1900s accidental observation suggesting that mind is based on matter.”
(Image - An image of a transgenic mouse hippocampus | Image: Nikon Small World Gallery)
Great collection from io9, featuring everything from da Vinci’s anatomy drawings to the über-fluorescent brainbow. The image at top shows the first image of molecular bonds via an atomic force microscope. Will it change the way we look at molecules?
I’m very much inspired by this man’s work. The use of movement and the human anatomy is amazing and beautiful. I hope to incorporate this into my future designs, especially my Disney Princess project for Advanced Painting and Senior Seminar.
Very cool animation of what happens during an impulse transmission between a presynaptic and postsynaptic neuron.
Endless forms, most beautiful … nature, you damn fine.
Beauty of Science: Neural Stem Cells Galore
Latin: Cellula Nervosa Precursoria
We all know at this point that Neurons are quite photogenic once you get it under the right lighting and scope, but what about their earlier years when they were just neural stem cells? Here’s a post I’ve been meaning to put together highlighting the beauty of the neural stem cell in swarms.
In other words they’re the cells that form up from the start in your nervous system to turn into different types of neural related cells.
the ossicles, three tiny bones in your middle ear
When sound waves reach the eardrum, they cause the eardrum to vibrate. When the eardrum vibrates, it moves the tiny ossicles — from the hammer to the anvil and then to the stirrup. These bones help sound move into the inner ear, among other things.
So cool to actually see this.
I realized that many of the things I want to write about on this blog mention, at least in passing, areas of the brain and how their functioning might influence our mental health. I set up Mind Over Matter in the hope of being able to provide a platform for patients, public & practitioners to engage in discussion of their experiences of mental health issues on a common level, but dropping neuroscience into this arena without explanation would put some of these groups at a disadvantage. With that in mind, here follows a whistle-stop tour of the brain. I do not claim this to be an exhaustive explanation, merely a little introduction to the basics…
The pink area above is the cerebral cortex, which is split into lobes. The frontal lobe (at the front, surprisingly), is associated with the executive cognitive functions, such as planning and decision making, error correction, responses in novel situations and inhibition of prepotent responses. Some of these executive functions are thought to be impaired in several psychiatric disorders, such as schizophrenia, where these so-called ‘cognitive symptoms’ may sometimes be the first to emerge in the prodromal phase of the disorder (i.e. before specific, differentiating symptoms occur).
The parietal lobe lies behind it and combines sensory information from different modalities. Some people with borderline personality disorder describe multi-modal hallucinations and can show impaired visuospatial capacity, which suggests some kind of different processing here.
The occipital lobe lies at the back of the brain and contains the visual cortex for processing of visual information from the optic nerve. I can’t think of anything off the top of my head about this lobe that would be relevant to psychiatry.
Last but not least is the temporal lobe, which we can’t actually see on this diagram because it is a sagittal section of the brain (dividing it from front to back into left and right portions) but, as the name suggests, it lies at the temples of the head. This area contains the auditory cortex and is thought to be associated with the auditory hallucinations common in schizophrenia. Interestingly, epilepsy in this area often leads to religious or spiritual sensations. It also contains the hippocampus and amygdala (see below).
The corpus callosum is a collection of about a quarter of a billion neuronal fibers connecting the left and right hemispheres. It is sometimes surgically severed in patients with intractable epilepsy to stop the massive seizures spreading from one half of the brain to the other & thus to minimise the damage involved. It was found that many of these patients showed an odd phenomenon after surgery of ‘split consciousness’.
The ventricles form a system of four communicating cavities that are continuous with the central canal of the spinal cord. It has been consistently shown that the lateral ventricles of schizophrenics are larger than controls, which relates to a lateral displacement of the corpus callosum in these individuals too.
Above we zoom in to view the hypothalamus, which controls body temperature, hunger, thirst, fatigue, sleep and the circadian cycles. The lateral hypothalamus is associated with hunger: lesioning this area causes a decrease in food intake & stimulating it causes an increase. The opposite pattern is found for the ventromedial hypothalamis, which is therefore identified as the ‘satiety centre’ of the brain. Because of its association with food intake, the hypothalamus is of great interest to researchers looking at a possible cause of eating disorders. It also forms part of the HPA axis (hypothalamic pituitary adrenal axis), which controls bodily responses to stress and is thought to be implicated in mood and anxiety disorders.
Above is the hippocampus. It is actually so named because it looks like a seahorse (hippocampe in French) - allegedly, but I struggle to see it. It plays an important role in long term memory and spatial navigation, but crops up in the literature concerning many psychiatric disorders too. It contains an area called the dentate gyrus, which is one of only a few areas in which adult neurogenesis (the birth of new neurons) occurs in humans.
Very near to this area is the amygdala, which is particularly involved in emotional learning and fear conditioning. This structure seems to be particularly sensitive in the anxious.
That was all highly generalised, but it was fun to try to write off the top of my head. Obviously there are hundreds more structures in the brain but I hope that this was a passable introduction!
Here’s a really wonderful introduction to the architecture of the human brain, as it relates to psychiatric disorders. Thank you mindovermatterzine!