Neuroscientists have long wondered how individual connections between brain cells remain diverse and "fit" enough for storing new memories. Reported in the prestigious science journal Neuron, a new study led by Dr. Inna Slutsky of the Sackler School of Medicine at Tel Aviv University describes what makes some memories stick.
The key is GABA (ã-Aminobutyric acid), a natural molecule that occurs in the brain, which could be the main factor in regulating how many new memories we can generate, the new study has found. The understanding of these mechanisms might lead to the development of new memory enhancers and new treatments for neurodegenerative diseases such as Alzheimer's.
Memories, Dr. Slutsky says, are stored in synaptic connections between neurons in our brain. In the past, other teams, including her own, have demonstrated that the strength of individual synapses is highly variable, even at the single neuron level. This variability ultimately determines if and how new memories are stored, and the key to this variability is GABA, a naturally-occurring chemical found in the brain.
In the hippocampus, one of the main areas of the brain involved in learning and memory, the strength of neuronal connections is known to be highly variable. Some neurons are tightly connected to others, while some appear to be "lone rangers."
The new paper, which examines individual synapses in the hippocampus, demonstrates that this process is regulated by GABA, the main inhibitory neurotransmitter in our brain. "We determined that variations in the local level of GABA in the vicinity of individual synapses are responsible for the differences or 'heterogeneity' of synaptic strength. And this heterogeneity may facilitate the formation of new memories," Dr. Slutsky explains.
Looking at the brain at rest
While looking at the brain in its basal state — when the activity was "at rest" before attempting to memorize a list of items or after a memory had been stored — Dr. Slutsky's team could actually "see" where synapses differ at different dendritic branches in the neuronal network. Those branches of neurons close to a cell body displayed a larger number of weak synapses, while the most distant branches were composed of a smaller number of strong synapses.
"Why the difference?" they asked. GABA was the answer. Higher concentrations of GABA near a synapse induced a stronger activation of its receptors, weakening basal synapse strength. As a result, GABA makes this synapse more liable to the formation of new memories, the researchers propose.
Dr. Slutsky, who previously discovered a basal-state regulator molecule, says that the research may also have implications for treating diseases of the mind. "We found that amyloid-beta, a well-known hallmark of Alzheimer's disease, regulates basal synapse strength in an opposite way to GABA," she notes, suggesting that an increase in the basal activity of synapses may initiate memory decline in Alzheimer's and other neurodegenerative disorders.
Experiments in the study were done using neuronal cultures and brain slices of rats subjected to molecular biology, optical imaging and electrophysiological techniques. The study also constituted a technical achievement, since it used advanced imaging techniques such as fluorescence resonance energy transfer (FRET) spectroscopy that looked at protein-to-protein interactions in the brain at the 10 nanometer scale. In the past, such fine resolution was impossible — brain scientists could only investigate interactions at the level of entire tissues, not between molecules at individual synapses.
George Hunka | EurekAlert!
WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf
First form of therapy for childhood dementia CLN2 developed
25.04.2018 | Universitätsklinikum Hamburg-Eppendorf
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology