, 2013)? What sort of interplay exists between LRRTM4, LRRTM1/2, and TARPs—all of which are expressed in the DG—in AMPAR regulation? Do they compete or cooperate with each other? Lastly, copy number variations of LRRTM4 and glypican 6 have been see more associated with autism spectrum disorders (Pinto et al., 2010). In addition, mutant mice that lack Ext1, which encodes an enzyme essential for HS biosynthesis, display autistic-like behaviors including impaired social interaction, reduced ultrasonic vocalizations,

and repetitive behaviors ( Irie et al., 2012). Whether and how deficits in LRRTM4-HSPG interactions contribute to the development of these disorders remain open questions. In conclusion, the two new studies demonstrate that postsynaptic LRRTM4 trans-synaptically interacts with presynaptic HSPGs to promote excitatory synapse development, identifying HSPGs as an unexpected group of presynaptic organizers. Fruitful avenues for future research include determining whether similar HSPG-dependent trans-synaptic adhesions are widespread

in various brain regions. If so, this would reinforce the importance of this newly emerging group of presynaptic organizers. “
“In selleck screening library the 1964 film Mary Poppins, Julie Andrews touts how “a spoonful of sugar helps the medicine go down,” reflecting that addition of sweet taste agonists can mask the presence of bitter compounds, like most medicines.

New work from Craig Montell’s laboratory studying taste behavior in Drosophila melanogastor ( Jeong et al., 2013) reveals how flies would not be easily swayed by Mary Poppins into taking their medicine by mixing bitter with sugar. Flies have distinct taste neurons tuned to bitter or sweet compounds, but when sweet and bitter compounds are mixed, the bitter tastants turn off the drive to consume sugar. In this issue of Neuron, Jeong et al. (2013) Olopatadine show the surprising mechanism behind how bitters trump sweet, through association with the odorant-binding protein (OBP) OBP49a and suppression of the sweet neuron activity ( Jeong et al., 2013). Taste is a critical sense that allows animals to evaluate the quality of food sources. Sweet taste is associated with the presence of energy-rich sugars, while bitter taste is associated with toxic or noxious compounds that might threaten the health of the animal. Sweet and bitter tastes are mediated by membrane receptors expressed on taste neurons that specifically detect these compounds. Receptors detecting sweet compounds are expressed by different neurons than those detecting bitter compounds, establishing “labeled lines” that allow the brain to distinguish between good, energy-rich foods and potentially toxic ones. There are approximately 120 taste neurons located in sensilla on the labellum (mouth) of the fly (Figures 1A and 1B).