Posts tagged memory recall
Articles and news from the latest research reports.
In-brain monitoring shows memory network
Working with patients with electrodes implanted in their brains, researchers at the University of California, Davis, and The University of Texas Health Science Center at Houston (UTHealth) have shown for the first time that areas of the brain work together at the same time to recall memories. The unique approach promises new insights into how we remember details of time and place.
"Previous work has focused on one region of the brain at a time," said Arne Ekstrom, assistant professor at the UC Davis Center for Neuroscience. "Our results show that memory recall involves simultaneous activity across brain regions." Ekstrom is senior author of a paper describing the work published Jan. 27 in the journal Nature Neuroscience.
Ekstrom and UC Davis graduate student Andrew Watrous worked with patients being treated for a severe seizure condition by neurosurgeon Dr. Nitin Tandon and his UTHealth colleagues.
To pinpoint the origin of the seizures in these patients, Tandon and his team place electrodes on the patient’s brain inside the skull. The electrodes remain in place for one to two weeks for monitoring.
Six such patients volunteered for Ekstrom and Watrous’ study while the electrodes were in place. Using a laptop computer, the patients learned to navigate a route through a virtual streetscape, picking up passengers and taking them to specific places. Later, they were asked to recall the routes from memory.
Correct memory recall was associated with increased activity across multiple connected brain regions at the same time, Ekstrom said, rather than activity in one region followed by another.
However, the analysis did show that the medial temporal lobe is an important hub of the memory network, confirming earlier studies, he said.
Intriguingly, memories of time and of place were associated with different frequencies of brain activity across the network. For example, recalling, “What shop is next to the donut shop?” set off a different frequency of activity from recalling “Where was I at 11 a.m.?”
Using different frequencies could explain how the brain codes and recalls elements of past events such as time and location at the same time, Ekstrom said.
"Just as cell phones and wireless devices work at different radio frequencies for different information, the brain resonates at different frequencies for spatial and temporal information," he said.
The researchers hope to explore further how the brain codes information in future work.
The neuroscientists analyzed their results with graph theory, a new technique that is being used for studying networks, ranging from social media connections to airline schedules.
"Previously, we didn’t have enough data from different brain regions to use graph theory. This combination of multiple readings during memory retrieval and graph theory is unique," Ekstrom said.
Placing electrodes inside the skull provides clearer resolution of electrical signals than external electrodes, making the data invaluable for the study of cognitive functions, Tandon said. “This work has yielded important insights into the normal mechanisms underpinning recall, and provides us with a framework for the study of memory dysfunction in the future.”
Research identifies a way to block memories associated with PTSD or drug addiction
New research from Western University could lead to better treatments for Post-Traumatic Stress Disorder (PTSD) and drug addiction by effectively blocking memories. The research performed by Nicole Lauzon, a PhD candidate in the laboratory of Steven Laviolette at Western’s Schulich School of Medicine & Dentistry has revealed a common mechanism in a region of the brain called the pre-limbic cortex, can control the recall of memories linked to both aversive, traumatic experiences associated with PTSD and rewarding memories linked to drug addiction. More importantly, the researchers have discovered a way to actively suppress the spontaneous recall of both types of memories, without permanently altering memories. The findings are published online in the journal Neuropharmacology.
“These findings are very important in disorders like PTSD or drug addiction. One of the common problems associated with these disorders is the obtrusive recall of memories that are associated with the fearful, emotional experiences in PTSD patients. And people suffering with addiction are often exposed to environmental cues that remind them of the rewarding effects of the drug. This can lead to drug relapse, one of the major problems with persistent addictions to drugs such as opiates,” explains Laviolette, an associate professor in the Departments of Anatomy and Cell Biology, and Psychiatry. “So what we’ve found is a common mechanism in the brain that can control recall of both aversive memories and memories associated with rewarding experience in the case of drug addiction.”
In their experiments using a rat model, the neuroscientists discovered that stimulating a sub-type of dopamine receptor called the “D1” receptor in a specific area of the brain, could completely prevent the recall of both aversive and reward-related memories. “The precise mechanisms in the brain that control how these memories are recalled are poorly understood, and there are presently no effective treatments for patients suffering from obtrusive memories associated with either PTSD or addiction,” says Lauzon. “If we are able to block the recall of those memories, then potentially we have a target for drugs to treat these disorders.”