Negative feedback stabilizes memories

August 28, 2013, UC Davis
Excitatory (E) neurons hold the memory. If their activity begins to slip, fast negative feedback (red) mediated by inhibitory (I) neurons can correct this slip before slower positive feedback loops (blue) bring the circuit back into balance. Credit: UC Davis graphic

(Medical Xpress)—Memories may be maintained in the brain through a mechanism familiar to any engineer—negative and positive feedback loops, according to researchers Sukbin Lim and Mark Goldman at the UC Davis Center for Neuroscience.

The work was published Aug. 18 in the journal Nature Neuroscience.

"The puzzle out there is: How do retain a memory without it slipping?" said Associate Professor Goldman. "For example, if you store a memory of the color yellow, why doesn't it slip over time into orange?"

Earlier models used positive feedback to maintain memories. The idea is that, if a memory starts to fade, the circuit gets a boost.

"The problem with positive feedback is that, without some additional mechanism, it's brittle—the system doesn't respond well to being perturbed," said Goldman, who also holds joint appointments in the Department of Neurobiology, Physiology and Behavior within the College of Biological Sciences, and the Department of Ophthalmology and Vision Science within the School of Medicine.

Goldman and Lim, a postdoctoral researcher, thought that these brain circuits might instead be doing something an engineer would do—stabilizing a system with . For example, a thermostat uses negative feedback to turn on heating or cooling depending on whether a room's temperature drifts below or above a set point.

The researchers built mathematical models to simulate the kinds of found in the cortex of the brain. Neurons are connected to each other through junctions that transmit either positive (excitatory) or negative (inhibitory) signals.

The modeling studies show that negative feedback can stabilize these circuits and allow them to store memories. What's more, the models show that these circuits should be robust to perturbations such as death of individual cells.

"Biological systems tend to be robust, so we wanted our models to reflect this robustness," Goldman said. The models also reflect key features of the circuitry observed in the brain's neocortex, he said.

Lim and Goldman further showed how positive feedback and negative feedback could work together in the same circuit, demonstrating how the brain may exploit multiple mechanisms to store memories.

Explore further: Researchers have found new role for mTOR in autism-related disorders

More information: Balanced cortical microcircuitry for maintaining information in working memory, DOI: 10.1038/nn.3492

Related Stories

Researchers have found new role for mTOR in autism-related disorders

June 3, 2013
(Medical Xpress)—Researchers have found a novel role for a protein that has been implicated in an autism-related disorder known as tuberous sclerosis complex (TSC).

How brain microcircuits integrate information from different senses

August 20, 2013
A new publication in the top-ranked journal Neuron sheds new light onto the unknown processes on how the brain integrates the inputs from the different senses in the complex circuits formed by molecularly distinct types of ...

Good or bad: Surprises drive learning in same neural circuits

December 6, 2011
Primates learn from feedback that surprises them, and in a recent investigation of how that happens, neurosurgeons have learned something new. The insight they gleaned from examining the response of specific brain tissues ...

Recommended for you

New neuron-like cells allow investigation into synthesis of vital cellular components

January 22, 2018
Neuron-like cells created from a readily available cell line have allowed researchers to investigate how the human brain makes a metabolic building block essential for the survival of all living organisms. A team led by researchers ...

Finding unravels nature of cognitive inflexibility in fragile X syndrome

January 22, 2018
Mice with the genetic defect that causes fragile X syndrome (FXS) learn and remember normally, but show an inability to learn new information that contradicts what they initially learned, shows a new study by a team of neuroscientists. ...

Epilepsy linked to brain volume and thickness differences

January 22, 2018
Epilepsy is associated with thickness and volume differences in the grey matter of several brain regions, according to new research led by UCL and the Keck School of Medicine of USC.

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.