Dr. Robert K. Ross
Dr. Robert K. Ross
Activating positive memory engrams suppresses depression-like behaviour
Nature 522, 335–339 (18 June 2015)
Steve Ramirez, … & Susumu Tonegawa
Here we acutely rescue stress-induced depression-related behaviours in mice by optogenetically reactivating dentate gyrus cells that were previously active during a positive experience. A brain-wide histological investigation, coupled with pharmacological and projection-specific optogenetic blockade experiments, identified glutamatergic activity in the hippocampus–amygdala–nucleus-accumbens pathway as a candidate circuit supporting the acute rescue.
dentate gyrus engram cells as potential therapeutic nodes for intervening with maladaptive behavioural states.
Subject terms: Hippocampus, Stress and resilience, Emotion
Activating happy memories cheers moody mice
17 June 2015
The work has grown out of studies … aimed to locate the memory engram — the physical trace of a memory, thought to be encoded in an ensemble of neurons.
More recently, the researchers used variations of the engram method to create false memories in mice, trigger lost memories and even retrain engram cells to encode a positive memory instead of a negative one.
By the sixth day, the previously stressed-out animals showed improved motivation and pleasure-seeking behaviours even after the light was turned off. “We were able to cure the animals’ depression,” …
the gap between simple animal models of depression and the complex human condition. “Depression in humans is a very heterogeneous clinical state. Some people have problems with motivation and experiencing reward, and other people don’t. … Optogenetic stimulation is not feasible in people, and deep-brain-stimulating implants, which involve invasive surgery, are used only as a last resort.
Neuroscience: The power of positivity
Alex Dranovsky & E. David Leonardo
Nature 522, 294–295 (18 June 2015)
Understanding how emotion-laden memories affect behaviour forms the bedrock of psychotherapy treatments, but the biology of this process is poorly understood.
Localization of a stable neural correlate of associative memory.
Science. 2007 Aug 31;317(5842):1230-3.
Reijmers LG1, Perkins BL, Matsuo N, Mayford M.
Do learning and retrieval of a memory activate the same neurons? Does the number of reactivated neurons correlate with memory strength? We developed a transgenic mouse that enables the long-lasting genetic tagging of c-fos-active neurons. We found neurons in the basolateral amygdala that are activated during Pavlovian fear conditioning and are reactivated during memory retrieval. The number of reactivated neurons correlated positively with the behavioral expression of the fear memory, indicating a stable neural correlate of associative memory. The ability to manipulate these neurons genetically should allow a more precise dissection of the molecular mechanisms of memory encoding within a distributed neuronal network.
BMC Biol. 2016 May 19;14(1):40. doi: 10.1186/s12915-016-0261-6.
What is memory? The present state of the engram.
Poo MM, et al.
The mechanism of memory remains one of the great unsolved problems of biology. Grappling with the question more than a hundred years ago, the German zoologist Richard Semon formulated the concept of the engram, lasting connections in the brain that result from simultaneous “excitations”, whose precise physical nature and consequences were out of reach of the biology of his day. Neuroscientists now have the knowledge and tools to tackle this question, however, and this Forum brings together leading contemporary views on the mechanisms of memory and what the engram means today.
Which Neurons Will Be the Engram – Activated Neurons and/or More Excitable Neurons?
Exp Neurobiol. 2016 Apr;25(2):55-63.
Kim JI, et al.
During past decades, the formation and storage principle of memory have received much attention in the neuroscience field. Although some studies have attempted to demonstrate the nature of the engram, elucidating the memory engram allocation mechanism was not possible because of the limitations of existing methods, which cannot specifically modulate the candidate neuronal population. Recently, the development of new techniques, which offer ways to mark and control specific populations of neurons, may accelerate solving this issue. Here, we review the recent advances, which have provided substantial evidence showing that both candidates (neuronal population that is activated by learning, and that has increased CREB level/excitability at learning) satisfy the criteria of the engram, which are necessary and sufficient for memory expression.
CREB; Memory allocation; Memory engram; Review; excitability
Neuronal Allocation to a Hippocampal Engram.
Neuropsychopharmacology. 2016 May 17.
Park S, et al
The dentate gyrus (DG) is important for encoding contextual memories, but little is known about how a population of DG neurons comes to encode and support a particular memory. One possibility is that recruitment into an engram depends on a neuron’s excitability (Han et al, 2009; Zhou et al, 2009; Choi et al, 2011; Sano et al, 2014). Here we manipulated excitability by overexpressing CREB in a random population of DG neurons and examined whether this biased their recruitment to an engram supporting a contextual fear memory. To directly assess whether neurons overexpressing CREB at the time of training became critical components of the engram, we examined memory expression while the activity of these neurons was silenced. Chemogenetically (hM4Di, an inhibitory DREADD receptor) or optogenetically (iC++, a light-activated chloride channel) silencing the small number of CREB-overexpressing DG neurons attenuated memory expression, while silencing a similar number of random neurons not overexpressing CREB at the time of training did not. As post-encoding reactivation of the activity patterns present during initial experience is thought to be important in memory consolidation, we investigated whether post-training silencing of neurons allocated to an engram disrupted subsequent memory expression. We found that silencing neurons 5 min (but not 24 h) following training disrupted memory expression. Together these results indicate that the rules of neuronal allocation to an engram originally described in the lateral amygdala are followed in different brain regions including DG, and moreover, that disrupting the post-training activity pattern of these neurons prevents memory consolidation.
Still searching for the engram.
Learn Behav. 2016 Mar 4.
For nearly a century, neurobiologists have searched for the engram-the neural representation of a memory. Early studies showed that the engram is widely distributed both within and across brain areas and is supported by interactions among large networks of neurons. Subsequent research has identified engrams that support memory within dedicated functional systems for habit learning and emotional memory, but the engram for declarative memories has been elusive. Nevertheless, recent years have brought progress from molecular biological approaches that identify neurons and networks that are necessary and sufficient to support memory, and from recording approaches and population analyses that characterize the information coded by large neural networks. These new directions offer the promise of revealing the engrams for episodic and semantic memories.
Comparative cognition; Episodic memory; Memory; Rat; Spatial learning
The Virtue of Hard Things
A study of Ivy League undergraduates showed that the smarter the students were, as measured by SAT scores, the less they persevered.
May 3, 2016
The Power of Passion and Perseverance
John Irving … has severe dyslexia, was a C-minus English student in high school and scored 475 out of 800 on the SAT verbal test.
How, then, did he have such a remarkably successful career as a writer?
New Yorker cartoon editor Bob Mankoff, who submitted some 2,000 drawings to the magazine …
Will Smith: “The only thing that I see that is distinctly different about me is: I’m not afraid to die on a treadmill. . . . If we get on the treadmill together, there’s two things: You’re getting off first, or I’m going to die.”
MacArthur ‘Genius’ Angela Duckworth Responds To A New Critique Of Grit
May 25, 2016
Much Ado about Grit: A Meta-Analytic Synthesis of the Grit Literature
Department of Psychology, Iowa State University
Clues To Autism, Schizophrenia Emerge From Cerebellum Research
March 17, 2015·
“Putting together a puzzle of a face,” Sherman says, “he initially had put the eyes in the wrong place and then looked at my face and said, ‘Oh, no, your nose actually goes between your eyes.’ ”
But during that time doctors and developmental health experts still didn’t know why Jonathan was having so much trouble. And that turned out to be a good thing, says his father, Richard. “Not knowing what the diagnosis was we said, ‘Well, let’s assume he can do everything,’ ” he says.
A Silver Lining to Experiencing Adverse Life Events?
Mark D. Seery
Current Directions in Psychological Science December 2011 vol. 20 no. 6 390-394
University at Buffalo, The State University of New York
When adverse life events occur, people often suffer negative consequences for their mental health and well-being. More adversity has been associated with worse outcomes, implying that the absence of life adversity should be optimal. However, some theory and empirical evidence suggest that the experience of facing difficulties can also promote benefits in the form of greater propensity for resilience when dealing with subsequent stressful situations.
I review research that demonstrates U-shaped relationships between lifetime adversity exposure and mental health and well-being, functional impairment and health care utilization in chronic back pain, and responses to experimentally induced pain.
Specifically, a history of some lifetime adversity predicts better outcomes than not only a history of high adversity but also a history of no adversity.
This has important implications for understanding resilience, suggesting that adversity can have benefits.
cumulative lifetime adversity
mental health and well-being
Primeros Auxilios Psicológicos
Universidad Autónoma de Barcelona.