News & Views in 2008

A new study shows that a subset of the glia that express the proteoglycan NG2 can fire action potentials, contradicting the dogma that only neurons are excitable in the brain. These glia receive excitatory and inhibitory synaptic input, are selectively vulnerable to ischemia and are present into adulthood, though their function remains mysterious.

Language is unique to humans, but did it evolve gradually or suddenly, from a chance mutation or as a consequence of a larger brain? Two studies now suggest that language may have arisen gradually from precursors in other primates.

Calcium is a ubiquitous second messenger in the nervous system linking extracellular and intracellular events. Now a study identifies it as a primary messenger controlling axon and dendrite outgrowth during development via activation of extracellular calcium-sensing receptors, better known in the liver and thyroid than in the brain.

Motor neurons and muscle fibers interact in complex ways to build the neuromuscular synapse. A new study shows that β-catenin is required in muscle to provide an unknown retrograde signal that is necessary for presynaptic transmitter release.

Descending projection neurons to the spinal cord carry important information for movement initiation and control. A new study shows that relatively few projection neurons may be needed to generate certain visually guided movements.

Even well-practiced skills show trial-by-trial variations. A study in Nature suggests that such variability may be adaptive, allowing for plasticity in apparently crystallized skills, which should therefore be considered more like templates.

Many aspects of sleep, including the how and why, are still mysterious, especially its relationship to learning and memory. A new study suggests that sleep may serve to reset synaptic potentiation, linking it to homeostatic plasticity.

New work in this issue shows that one principal endocannabinoid, anandamide, directly inhibits the synthesis of another, 2-arachidonoylglycerol. This finding could explain a number of puzzling observations in the endocannabinoid field.

Learning is believed to be a result of plasticity in synaptic architecture, but few studies have shown this directly. A new paper explores a mechanism that shapes the formation of associative connections between neurons in behaving animals.

Mice use pheromones to regulate social behavior. New work in mice now identifies the protein in urine that is essential for aggressive behavior, along with the specific subclass of neurons involved in its processing.

Drosophila courtship is a complex behavior. A new study shows that glia modulate neurotransmission to influence male preference, but the authors should have resisted the temptation to describe their results in tabloid language.

Changes in neuronal firing underlie sensation, but how many neurons are needed to perceive these activity shifts? Two new studies in Nature suggest that the experimental modulation of only a few neurons can influence perception.

Efficiency variations in the filtering of relevant from irrelevant information could contribute to individual differences in working memory. A new functional imaging study suggests that the basal ganglia act as this filter because activity in this region before stimulus presentation was inversely correlated with unnecessary storage.

A new study proposes that synaptic vesicle endocytosis at a large synaptic terminal is partly independent of dynamin and GTP hydrolysis, suggesting a new mechanism leading to vesicle fission and maintenance of neurotransmission.