Activating a small fraction of neurons triggers complete memory.

By Lizzie Buchen

Just as a whiff of pumpkin pie can unleash powerful memories of holiday dinners, the stimulation of a tiny number of neurons can evoke entire memories, new research in mice suggests.

Memories are stored in neurons distributed across a host of brain regions. When something triggers a memory, that diffuse information is immediately and cohesively reactivated, but it's unclear how the circuit gets kicked into full gear. Over the past few years, a handful of studies have suggested that a small number of neurons — perhaps even single neurons — can trigger sensations. But this idea remains controversial and has never been demonstrated with memory.

Written by Nicole Giese

Amputations trigger a molecular response that determines if a head or tail will be regrown in planaria, a flatworm commonly studied for its regenerative capabilities. Until now, no molecular connection between wounding and the decision to regenerate either a head or tail in planaria had been identified. 

Whitehead Institute scientists report this finding in the September 15-28 issue of PNAS Early Edition.

ANN ARBOR, Mich.—University of Michigan mathematicians and their British colleagues say they have identified the signal that the brain sends to the rest of the body to control biological rhythms, a finding that overturns a long-held theory about our internal clock.

Understanding how the human biological clock works is an essential step toward correcting sleep problems like insomnia and jet lag. New insights about the body's central pacemaker might also, someday, advance efforts to treat diseases influenced by the internal clock, including cancer, Alzheimer's disease and mood disorders, said University of Michigan mathematician Daniel Forger.

geckoGreater Mekong - A bird eating fanged frog, a gecko that looks like it’s from another planet and a bird which would rather walk than fly, are among the 163 new species discovered in the Greater Mekong region last year that are now at risk of extinction due to climate change, says a new report launched by WWF ahead of UN climate talks in Bangkok.

listeriaBy Zenaida Gonzalez Kotala

University of Central Florida Microbiology Professor Keith Ireton has uncovered a previously unknown mechanism that plays an important role in the spread of a deadly food-borne bacterium.

Listeria monocytogenes is a bacterium that can cause pregnant women to lose their fetuses and trigger fatal cases of meningitis in the elderly or people with compromised immune systems. The bacterium has been linked to outbreaks traced to food processing plants in the U.S. and Canada.

best in science, biology, plant, animal, hormonesA reaction similar to the inactivation of prostaglandin hormones has now been discovered in the larval guts of two plant pest species. The insects bear an enzyme which structurally modifies and thereby inactivates OPDA, a highly active plant hormone. The results illustrate the close relationships and interactions of hormone activities in the animal and plant kingdom.

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