02020-02-04: Burn Scars in Australia

The septo-hippocampal cholinergic system is critical for hippocampal learning and memory. However, a quantitative description of the in vivo firing patterns and physiological function of medial septal (MS) cholinergic neurons is still missing. In this study, we combined optogenetics with multichannel in vivo recording and recorded MS cholinergic neuron firings in freely behaving male mice for 5.5–72 h. We found that their firing activities were highly correlated with hippocampal theta states. MS cholinergic neurons were highly active during theta-dominant epochs, such as active exploration and rapid eye movement sleep, but almost silent during non-theta epochs, such as slow-wave sleep (SWS). Interestingly, optogenetic activation of these MS cholinergic neurons during SWS suppressed CA1 ripple oscillations. This suppression could be rescued by muscarinic M₂ or M₄ receptor antagonists. These results suggest the following important physiological function of MS cholinergic neurons: maintaining high hippocampal acetylcholine level by persistent firing during theta epochs, consequently suppressing ripples and allowing theta oscillations to dominate.

SIGNIFICANCE STATEMENT The major source of acetylcholine in the hippocampus comes from the medial septum. Early experiments found that lesions to the MS result in the disappearance of hippocampal theta oscillation, which leads to speculation that the septo-hippocampal cholinergic projection contributing to theta oscillation. In this article, by long-term recording of MS cholinergic neurons, we found that they show a theta state-related firing pattern. However, optogenetically activating these neurons shows little effect on theta rhythm in the hippocampus. Instead, we found that activating MS cholinergic neurons during slow-wave sleep could suppress hippocampal ripple oscillations. This suppression is mediated by muscarinic M₂ and M₄ receptors.

Dopaminergic neurons innervate extensive areas of the brain and release dopamine (DA) onto a wide range of target neurons. However, DA release is also precisely regulated. In Drosophila melanogaster brain explant preparations, DA is released specifically onto α3/α'3 compartments of mushroom body (MB) neurons that have been coincidentally activated by cholinergic and glutamatergic inputs. The mechanism for this precise release has been unclear. Here we found that coincidentally activated MB neurons generate carbon monoxide (CO), which functions as a retrograde signal evoking local DA release from presynaptic terminals. CO production depends on activity of heme oxygenase in postsynaptic MB neurons, and CO-evoked DA release requires Ca²⁺ efflux through ryanodine receptors in DA terminals. CO is only produced in MB areas receiving coincident activation, and removal of CO using scavengers blocks DA release. We propose that DA neurons use two distinct modes of transmission to produce global and local DA signaling.

SIGNIFICANCE STATEMENT Dopamine (DA) is needed for various higher brain functions, including memory formation. However, DA neurons form extensive synaptic connections, while memory formation requires highly specific and localized DA release. Here we identify a mechanism through which DA release from presynaptic terminals is controlled by postsynaptic activity. Postsynaptic neurons activated by cholinergic and glutamatergic inputs generate carbon monoxide, which acts as a retrograde messenger inducing presynaptic DA release. Released DA is required for memory-associated plasticity. Our work identifies a novel mechanism that restricts DA release to the specific postsynaptic sites that require DA during memory formation.

Water is essential for agricultural production and food security.  It is the lifeblood of ecosystems, including forests, lakes and wetlands, on which the food and nutritional security of present and future generations depends on. Yet, our freshwater resources are dwindling at an alarming rate. Growing water scarcity is now one of the leading challenges for sustainable development.  This challenge will [...]

New research hints at how different environments impact animal behavior and the spread of infection

The puzzling glyph, which bears some resemblance to the "squatting man" motif, suggests that insects have long held a place in human lore

Storms reveal, then hide, the ship's sand-covered remains every decade or so

Doctors and nurses are attaching smiling photos of themselves to the outside of their protective gear to maintain connections with patients

Expelled by animals as a waste product, the gas appears to play a crucial role in keeping these bizarre, burrowing rodents safe

Browse the collections for artworks with a CC0 license as part of the Smithsonian's Open Access Initiative,

As New Brunswick's economy slowly opens up, the province's daycares are waiting for the call to action, says the head of the group that represents them. 

Some New Brunswickers will be heading back to work next week, but their regular childcare facilities may not be available. 

Some farmers across the province are worried about getting their fuel in time for spring seeding. The Agricultural Producers Association of Saskatchewan says it has been fielding complaints this week about delays at the Co-op cardlock near Moose Jaw.

A St. John's cardiologist says public health restrictions put in place under the COVID-19 pandemic, while justified, may be harming cardiac patients whose procedures have been postponed indefinitely as well as heart patients who are avoiding hospitals.

Long-term care homes in Eastern Health's jurisdiction are allowing for people to again visit their relatives by windows, just in time for Mother's Day. 

The Porcupine Health Unit is declaring a COVID-19 outbreak at a long-term care home in Iroquois Falls.

The City of Timmins says a COVID-19 outbreak remains in place at a long-term care home in the city, even after the one affected resident has now tested negative — twice.

The following is a guest post by Martha H. Kennedy, Curator of Popular & Applied Graphic Art, Prints & Photographs Division. During Will Eisner Week, March 1-7, 2020, the Library of Congress joins art schools, libraries, universities, and museums in a global celebration of this legendary creator’s contributions to the world of comic art and […]

The American Geriatrics Society annually honors researchers, clinicians, educators, and emerging health professionals who have made outstanding contributions to high-quality, person-centered care for older people.

Police say efforts to find the driver of an abandoned car in Kings County last week likely saved his life.

For those working in CHSLDs — the province's long-term care homes which are the site of the most serious outbreaks — the bonus will amount to as much as $1,000 per month.

Quebec's public health director, Dr. Horacio Arruda, says grandparents under 70 years old are allowed to see and even care for their grandchildren. But the recommendation comes with cautions.

Asylum seekers make up a large portion of the "guardian angels" Quebec Premier François Legault has praised in his daily COVID-19 briefings: the orderlies who have no guarantee they'll be allowed to stay in Canada.

A young boy is recovering in hospital after being hit by a car in Montreal's LaSalle borough Friday afternoon, police say.

We're answering your questions about the pandemic. Send yours to COVID@cbc.ca and we’ll answer as many as we can. We’ll publish a selection of answers every weekday online, and also put some questions to the experts during The National and on CBC News Network.

Manitoba health officials says visits can be done via the internet, through window panes, or outside at a distance if everyone is healthy. People whose moms are in a hospital or a care home can still drop off gifts of food or clothing.

Health PEI plans to create a COVID-19 unit within the Prince Edward Home to be used for any long-term care resident — living in any long-term care facility on the Island — who is diagnosed with the virus.

Robbyn Plumb tried to balance a career in the public service with looking after two kids, one with special needs. When the pandemic hit she finally hit a wall and decided to stop working. She writes about how hard it is for parents trying to do it all during COVID-19.

Despite having no ice on which to perform, more than 40 figure skaters from nine countries will take part in a fundraiser Friday to help health care workers on the front lines battling the new coronavirus.

Former Canadian figure skater and Olympic medallist Joannie Rochette will be working at Quebec's long-term care homes hit hard by COVID-19.

The 19-year-old has declared for the 2020 NBA Draft. If selected he would become the first player out of CEGEP program in Quebec to make the leap directly to the world's top basketball league.

Michell Jesse said the personal care home operators she represents have been frustrated trying to keep up with the government's direction during an already stressful time.

A Saskatchewan daughter said her mom has been “confined” to her room at a government run health-care facility due to COVID-19. 

The New York Post is reporting that Drew Brees will join NBC after he retires. The 41-year old New Orleans Saints quarterback will be going into his 20th NFL season this year.

It turns out a small black box with a dangling red wire and little blue light investigated by Windsor's bomb squad Tuesday isn't actually dangerous — at least to the living.

UFC 249 will proceed as planned Saturday night despite Ronaldo "Jacare" Souza being ruled out Friday following a positive test for the coronavirus. He was scheduled to oppose Uriah Hall in Jacksonville, Fla.

Madagascar is putting its self-proclaimed, plant-based "cure" for COVID-19 on sale and several countries in Africa have already put in orders for purchase, despite warnings from the World Health Organization that its efficacy is unproven.

Cardinal Robert Sarah, head of the Vatican's liturgy office, claims he never signed a petition claiming the coronavirus is an over-hyped "pretext" to deprive the faithful of Mass.

40 classic cars drove through High River to give thanks to those working on the front lines.

Jose, an Argentinian worker serving in Southeast Asia, tells of how he entered overseas service and what he has seen God do through his not-so-typical ministry.

Montreal Canadiens goaltender Carey Price has reached out to give support to two boys who lost their parents during the Nova Scotia mass shooting last month.

Will he, given his obsession with the economy?

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