Navigation Links
Finding the way to memory

This release is available in French.

Our ability to learn and form new memories is fully dependent on the brain's ability to be plastic that is to change and adapt according to new experiences and environments. A new study from the Montreal Neurological Institute The Neuro, McGill University, reveals that DCC, the receptor for a crucial protein in the nervous system known as netrin, plays a key role in regulating the plasticity of nerve cell connections in the brain. The absence of DCC leads to the type of memory loss experienced by Dr. Brenda Milner's famous subject HM. Although HM's memory loss resulted from the removal of an entire brain structure, this study shows that just removing DCC causes the same type of memory deficit. The finding published in this week's issue of Cell Reports, extends Dr. Milner's seminal finding to another level, revealing a key part of the molecular basis for learning and memory.

Although both netrin and DCC are essential for normal development (in terms of guiding nerve cell growth) until now their function in the adult brain was not known. Dr. Tim Kennedy, lead researcher and neuroscientist at The Neuro, contributed to the discovery of netrins as a young post-doctoral fellow. This new study reveals the answer to the question that drove him to first start a lab. "I remember that exact moment when I knew I could run a research lab, it was 1993 and I was studying the developing nervous system and I was amazed to spot netrins in the adult brain - raising the important question, 'what are they doing there?' 20 years of dedicated research later the answer provides an important piece of the puzzle for understanding our nervous system and neurological disorders.

"The power of this study is that it looks at the animal on all levels, molecular, structural, and behavioural. We show that the netrin receptor DCC is a critical component of synapses between neurons in the adult brain, and is required for synapses to function properly. To demonstrate this, we selectively removed DCC from a specific subset of neurons in the adult mouse brain. This results in progressive degeneration of synapses, leading to defects in synaptic plasticity and memory. The synapses continue to function in that they still communicate but, the synapses cannot adjust or change in response to new experiences. Therefore, you can't learn anymore."

Furthermore, DCC deletion from mature neurons results in changes in the shape of specialized protrusions called dendritic spines, and alters the NMDA receptor, a critical trigger for mechanisms that make changes in synaptic strength. Therefore the study reveals that DCC is required to maintain proper synapse morphology or shape, and to regulate the ability of the NMDA receptor to switch on, which ensures activity-dependent synaptic plasticity.

Mutant mice that entirely lack DCC in all cells do not survive past birth and exhibit major defects in brain development. In order to investigate the function of netrin in the adult brain, researchers from the Netherlands Cancer Institute, collaborators on this study, engineered a new strain of floxed mice, in which the DCC gene can be selectively deleted from a specific sub-set of cells. Floxing involves putting short sequences of DNA on either side of a gene sequence. An enzyme that is activated later in life then recombines the DNA and cuts out the intervening sequence deleting the gene only from specific cells. The Kennedy lab activated this enzyme only in the mature mouse brain, and limited activation to only a subset of neurons, consequently deleting the DCC gene from only from these neurons. These mice live to adulthood (DCC is made normally in all other cells in the mouse) as the enzyme only turns on and deletes DCC in specific cells in the adult brain. Although the mice otherwise appear normal, testing their behavior revealed severe deficits in their ability to form certain types of new long-term memories.

This study provides important new insight into the neural mechanisms of learning and memory, processes that are fundamental to our existence, survival, and everyday life.


Contact: Anita Kar
McGill University

Related biology news :

1. A*STAR scientists solve century-old mystery by finding stable haploid strains of Candida albicans
2. Chance finding reveals new control on blood vessels in developing brain
3. Promising new finding for therapies to treat persistent seizures in epileptic patients
4. New findings in the search for genetic clues to insulin production
5. The findings between DNMs and autism provides global view of mutability on human diseases
6. Finding life in the volcanic systems of the Antarctic Polar Front
7. Mercury releases contaminate ocean fish: Dartmouth-led effort publishes major findings
8. Stem cell finding could advance immunotherapy for lung cancer
9. Verinata Health Announces New Findings At The American Society Of Human Genetics
10. New findings on gene regulation and bone development
11. Finding triggers of birth defects in an embryo heart
Post Your Comments:
(Date:11/18/2015)... PHILADELPHIA , Nov. 18, 2015  As new ... in children, doctors and other healthcare providers face challenges ... counsel families and patients. In addition, as more children ... into a patient,s adulthood and old age. ... The Children,s Hospital of Philadelphia (CHOP) . ...
(Date:11/17/2015)... Nov. 17, 2015  Vigilant Solutions announces today that ... Board of Directors. --> ... retiring from the partnership at TPG Capital, one of ... over $140 Billion in revenue.  He founded and led ... the TPG companies, from 1997 to 2013.  In his ...
(Date:11/12/2015)... CAMBRIDGE, Mass. , Nov. 12, 2015 /PRNewswire/ ... Broad Institute of MIT and Harvard for use ... chemical discovery information management tools. The partnership will ... share both biological and chemical research information internally ... tools will be used for managing the Institute,s ...
Breaking Biology News(10 mins):
(Date:11/30/2015)... Israel , Nov. 30, 2015 BrainStorm Cell ... of adult stem cell technologies for neurodegenerative diseases, today announced ... awarded an additional grant of approximately $735,000 from ... grant, the second this year, brings the total awarded by ... (approximately NIS7 million).  ...
(Date:11/27/2015)... PA (PRWEB) , ... November 27, 2015 , ... ... Technical Program that includes over 2,000 technical presentations offered in symposia, oral ... chemistry and applied spectroscopy, covers a wide range of applications such as, but ...
(Date:11/26/2015)... November 26, 2015 --> ... specializing in imaging technologies, announced today that it has received ... of the Horizon 2020 European Union Framework Programme for Research ... clinical trial in breast cancer. , --> ... --> --> The study aims ...
(Date:11/25/2015)... -- 2 nouvelles études permettent d , ... entre les souches bactériennes retrouvées dans la plaque ... . Ces recherches  ouvrent une nouvelle voie ... efficace de l,un des problèmes de santé les ...    --> 2 nouvelles études permettent d ...
Breaking Biology Technology: