Tag: Olfaction

Elongator complex is required for long-term olfactory memory formation in Drosophila

Elongator complex is required for long-term olfactory memory formation in Drosophila

Published in: Learning & Memory, Volume 25, Issue 4, 183-196

Abstract
“The evolutionarily conserved Elongator Complex associates with RNA polymerase II for transcriptional elongation. Elp3 is the catalytic subunit, contains histone acetyltransferase activity, and is associated with neurodegeneration in humans. Elp1 is a scaffolding subunit and when mutated causes familial dysautonomia. Here, we show that elp3 and elp1 are required for aversive long-term olfactory memory in Drosophila. RNAi knockdown of elp3 in adult mushroom bodies impairs long-term memory (LTM) without affecting earlier forms of memory. RNAi knockdown with coexpression of elp3 cDNA reverses the impairment. Similarly, RNAi knockdown of elp1 impairs LTM and coexpression of elp1 cDNA reverses this phenotype. The LTM deficit in elp3 and elp1 knockdown flies is accompanied by the abolishment of a LTM trace, which is registered as increased calcium influx in response to the CS+ odor in the α-branch of mushroom body neurons. Coexpression of elp1 or elp3cDNA rescues the memory trace in parallel with LTM. These data show that the Elongator complex is required in adult mushroom body neurons for long-term behavioral memory and the associated long-term memory trace.”

Written by: Dinghui Yu, Ying Tan, Molee Chakraborty, Seth Tomchik, Ronald L. Davis
For full text: http://learnmem.cshlp.org/content/25/4/183.full

α2-Adrenergic receptor activation promotes long-term potentiation at excitatory synapses in the mouse accessory olfactory bulb

α2-Adrenergic receptor activation promotes long-term potentiation at excitatory synapses in the mouse accessory olfactory bulb

Published in: Learning & Memory, Volume 25, Issue 4, 147-157

Abstract
“The formation of mate recognition memory in mice is associated with neural changes at the reciprocal dendrodendritic synapses between glutamatergic mitral cell (MC) projection neurons and GABAergic granule cell (GC) interneurons in the accessory olfactory bulb (AOB). Although noradrenaline (NA) plays a critical role in the formation of the memory, the mechanism by which it exerts this effect remains unclear. Here we used extracellular field potential and whole-cell patch-clamp recordings to assess the actions of bath-applied NA (10 µM) on the glutamatergic transmission and its plasticity at the MC-to-GC synapse in the AOB. Stimulation (400 stimuli) of MC axons at 10 Hz but not at 100 Hz effectively induced N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP), which exhibited reversibility. NA paired with subthreshold 10-Hz stimulation (200 stimuli) facilitated the induction of NMDA receptor-dependent LTP via the activation of α2-adrenergic receptors (ARs). We next examined how NA, acting at α2-ARs, facilitates LTP induction. In terms of acute actions, NA suppressed GC excitatory postsynaptic current (EPSC) responses to single pulse stimulation of MC axons by reducing glutamate release from MCs via G-protein coupled inhibition of calcium channels. Consequently, NA reduced recurrent inhibition of MCs, resulting in the enhancement of evoked EPSCs and spike fidelity in GCs during the 10-Hz stimulation used to induce LTP. These results suggest that NA, acting at α2-ARs, facilitates the induction of NMDA receptor-dependent LTP at the MC-to-GC synapse by shifting its threshold through disinhibition of MCs.”

Written by: Guang-Zhe Huang, Mutsuo Taniguchi, Ye-Bo Zhou, Jing-Ji Zhang, Fumino Okutani, Yoshihiro Murata, Masahiro Yamaguchi, Hideto Kaba
For full text: http://learnmem.cshlp.org/content/25/4/147.full

Lexical olfaction recruits olfactory orbitofrontal cortex in metaphorical and literal contexts

Lexical olfaction recruits olfactory orbitofrontal cortex in metaphorical and literal contexts

Published in: Brain and Language, Volume 179, April 2018, 11-21

Abstract
“The investigation of specific lexical categories has substantially contributed to advancing our knowledge on how meaning is neurally represented. One sensory domain that has received particularly little attention is olfaction. This study aims to investigate the neural representation of lexical olfaction. In an fMRI experiment, participants read olfactory metaphors, their literal paraphrases, and literal olfactory sentences. Regions of interest were defined by a functional localizer run of odor processing. We observed activation in secondary olfactory areas during metaphorical and literal olfactory processing, thus extending previous findings to the novel source domain of olfaction. Previously reported enhanced activation in emotion-related areas due to metaphoricity could not be replicated. Finally, no primary olfactory cortex was found active during lexical olfaction processing. We suggest that this absence is due to olfactory hedonicity being crucial to understand the meaning of the current olfactory expressions. Consequently, the processing of olfactory hedonicity recruits secondary olfactory areas.”

Written by: Jennifer Pomp, Anne-Kathrin Bestgen, Patrick Schuzle, Christina J. Müller, Francesca M.M. Citron, Boris Suchan, Lars Kuchinke
For full text: https://doi.org/10.1016/j.bandl.2018.02.001

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