Scientists identify neurotranmitters that lead to forgetting
While we often think of memory as a way of preserving the essential idea of who we are, little thought is given to the importance of forgetting to our wellbeing, whether what we forget belongs in the "horrible memories department" or just reflects the minutia of day-to-day living.
Despite the fact that forgetting is normal, exactly how we forgetthe molecular, cellular, and brain circuit mechanisms underlying the processis poorly understood.
Now, in a study that appears in the May 10, 2012 issue of the journal Neuron, scientists from the Florida campus of The Scripps Research Institute have pinpointed a mechanism that is essential for forming memories in the first place and, as it turns out, is equally essential for eliminating them after memories have formed.
"This study focuses on the molecular biology of active forgetting," said Ron Davis, chair of the Scripps Research Department of Neuroscience who led the project. "Until now, the basic thought has been that forgetting is mostly a passive process. Our findings make clear that forgetting is an active process that is probably regulated."
The Two Faces of Dopamine
To better understand the mechanisms for forgetting, Davis and his colleagues studied Drosophila or fruit flies, a key model for studying memory that has been found to be highly applicable to humans. The flies were put in situations where they learned that certain smells were associated with either a positive reinforcement like food or a negative one, such as a mild electric shock. The scientists then observed changes in the flies' brains as they remembered or forgot the new information.
The results showed that a small subset of dopamine neurons actively regulate the acquisition of memories and the forgetting of these memories after learning, using a pair of dopamine receptors in the brain. Dopamine is a neurotransmitter that plays an important role in a number of processes including punishment and reward, memory, learning and cognition.
But how can a single neurotransmitter, dopamine, have two seemingly opposite roles in both forming and eliminating memories? And how can these two dopamine receptors serve acquiring memory on the one hand, and forgetting on the other?
The study suggests that when a new memory is first formed, there also exists an active, dopamine-based forgetting mechanismongoing dopamine neuron activitythat begins to erase those memories unless some importance is attached to them, a process known as consolidation that may shield important memories from the dopamine-driven forgetting process.
The study shows that specific neurons in the brain release dopamine to two different receptors known as dDA1 and DAMB, located on what are called mushroom bodies because of their shape; these densely packed networks of neurons are vital for memory and learning in insects. The study found the dDA1 receptor is responsible for memory acquisition, while DAMB is required for forgetting.
When dopamine neurons begin the signaling process, the dDA1 receptor becomes overstimulated and begins to form memories, an essential part of memory acquisition. Once that memory is acquired, however, these same dopamine neurons continue signaling. Except this time, the signal goes through the DAMB receptor, which triggers forgetting of those recently acquired, but not yet consolidated, memories.
Jacob Berry, a graduate student in the Davis lab who led the experimentation, showed that inhibiting the dopamine signaling after learning enhanced the flies' memory. Hyperactivating those same neurons after learning erased memory. And, a mutation in one of the receptors, dDA1, produced flies unable to learn, while a mutation in the other, DAMB, blocked forgetting.
While Davis was surprised by the mechanisms the study uncovered, he was not surprised that forgetting is an active process. "Biology isn't designed to do things in a passive way," he said. "There are active pathways for constructing things, and active ones for degrading things. Why should forgetting be any different?"
The study also brings into a focus a lot of intriguing issues, Davis saidsavant syndrome, for example.
"Savants have a high capacity for memory in some specialized areas," he said. "But maybe it isn't memory that gives them this capacity, maybe they have a bad forgetting mechanism. This also might be a strategy for developing drugs to promote cognition and memorywhat about drugs that inhibit forgetting as cognitive enhancers?"
More information: "Dopamine is required for Learning and Forgetting in Drosophila" www.cell.com/neuro… 3(12)00338-8
Provided by The Scripps Research Institute
- In learning, the brain forgets things on purpose Feb 18, 2010 | not rated yet | 0
- Forgetting is part of remembering Oct 18, 2011 | not rated yet | 0
- Scientists shed light on age-related memory loss and possible treatments Apr 02, 2012 | not rated yet | 0
- Scientists identify mechanism of long-term memory Apr 13, 2011 | not rated yet | 0
- Witnesses' memories can be improved May 11, 2007 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013 From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
May 17, 2013 I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
Ratio of Hydrogen of Oxygen in Dessicated Animal Protein
May 13, 2013 As an experiment, for the past few months I've been consuming at least one portion of Jell-O or unflavored Knox gelatin per day. I'm 64, in very...
Alcohol and acetaminophen
May 13, 2013 Edit: sorry for the typo in the title , can't edit I looked around on google quite a bit and it's very hard to find precise information on the...
Marie Curie's leukemia
May 13, 2013 Does anyone know what might be the cause of Marie Curie's cancer
- More from Physics Forums - Medical Sciences
More news stories
(Medical Xpress)—A three-year multinational study has tracked and detailed the progression of Huntington's disease (HD), predicting clinical decline in people carrying the HD gene more than 10 years before ...
Neuroscience 14 minutes ago | not rated yet | 0
While Huntington's disease (HD) is currently incurable, the HD research community anticipates that new disease-modifying therapies in development may slow or minimize disease progression. The success of HD research depends ...
Neuroscience 12 hours ago | 5 / 5 (1) | 0
Study shows premature birth interrupts vital brain development processes leading to reduced cognitive abilities
Researchers from King's College London have for the first time used a novel form of MRI to identify crucial developmental processes in the brain that are vulnerable to the effects of premature birth. This new study, published ...
Neuroscience 15 hours ago | 5 / 5 (1) | 0 |
While the effects of acute stroke have been widely studied, brain damage during the subacute phase of stroke has been a neglected area of research. Now, a new study by the University of South Florida reports that within a ...
Neuroscience 17 hours ago | 5 / 5 (1) | 0 |
Over the past few decades, neuroscientists have made much progress in mapping the brain by deciphering the functions of individual neurons that perform very specific tasks, such as recognizing the location ...
Neuroscience 20 hours ago | 4.9 / 5 (11) | 1 |
No new human cases of the H7N9 virus have been recorded in China for a week, national health authorities said, for the first time since the outbreak began in March.
47 minutes ago | not rated yet | 0
A Nobel prize-winning scientist Tuesday played down "shock-horror scenarios" that a new virus strain will emerge with the potential to kill millions of people.
1 hour ago | 5 / 5 (1) | 0
Johns Hopkins researchers say they have discovered specific chemical alterations in two genes that, when present during pregnancy, reliably predict whether a woman will develop postpartum depression.
2 hours ago | not rated yet | 0 |
(Medical Xpress)—A research team, led by Jeremy Barr, a biology post-doctoral fellow, unveils a new immune system that protects humans and animals from infection.
11 hours ago | 4.6 / 5 (13) | 5 |
Researchers have pinpointed a catalytic trigger for the onset of Alzheimer's disease – when the fundamental structure of a protein molecule changes to cause a chain reaction that leads to the death of neurons ...
15 hours ago | 5 / 5 (3) | 0 |
Children who have suffered maltreatment are 36% more likely to be obese in adulthood compared to non-maltreated children, according to a new study by King's College London. The authors estimate that the prevention or effective ...
2 hours ago | not rated yet | 0