Ultrastructural distribution of presynaptic active zones and dense core vesicles in olfactory projection neurons of Drosophila

In Drosophila melanogaster, olfactory projection neurons (PNs) convey odor information from peripheral olfactory center, antenna lobe, to central olfactory center, mushroom body (MB), and lateral horn (LH). In MB, the mechanisms underlining the transformation from coarse-coding PNs to sparse-coding MB intrinsic Kenyon cells (KCs) remain an open question. Here, we used HRP-labeled electron microscopy (EM) to volume reconstruct 89 PN axonal boutons in a reference area of the input region, the calyx of MB. The results showed that the number of presynaptic active zones (PAZs), neurotransmitter release site, is in positive linear correlation with the surface area of PN axonal boutons, while the number of dense core vesicles (DCVs), vesicles that containing neuropeptides, monoamines, or neurotrophic factors, is weakly related to the morphology of PN axonal boutons. Further analysis illustrated that DCVs preferentially exist in PN axonal boutons labeled by GH146-GAL4, a most widely used genetic marker for studying olfactory PNs. Our data suggest that synapses are uniformly distributed on the surface of all PN boutons, thus the neurotransmission capability of a PN axonal bouton could be predicted by its size, and PN subtypes release neuropeptides, monoamines, or neurotrophic factors, as well as classical neurotransmitters, to mediate the PN-KC transformation.

Metáfora é diálogo: uma proposta de interface

<p>Neste estudo, pretende-se desenhar uma abordagem da metáfora na interface metateórica (COSTA, 2007). Pretende-se ilustrar como, por meio do diálogo interdisciplinar, novas abordagens para a metáfora podem ser construídas. Para tanto, de um lado, apresentam-se os fundamentos da Pragmática que explicam como se processam os enunciados metafóricos e, de outro, apresentam-se achados em Neurociência que, por sua vez, descrevem, via coarse-coding hypothesis, os correlatos neurais desse<br />processamento. Postas em diálogo, dessas diferentes áreas emergem propriedades complexas que podem contribuir para o aprofundamento do potencial descritivo e explanatório da abordagem interdisciplinar. Além disso, pode-se também reacender e complexificar as possibilidades de diálogo entre teorias, à medida que propriedades complexas interagem entre si.</p><p><br />Palavras-chave: Metáfora. Interface metateórica. Teoria das implicaturas conversacionais. Teoria da relevância. Neurociência.</p>

Does Congenital Deafness Affect the Structural and Functional Architecture of Primary Visual Cortex?

Deafness results in greater reliance on the remaining senses. It is unknown whether the cortical architecture of the intact senses is optimized to compensate for lost input. Here we performed widefield population receptive field (pRF) mapping of primary visual cortex (V1) with functional magnetic resonance imaging (fMRI) in hearing and congenitally deaf participants, all of whom had learnt sign language after the age of 10 years. We found larger pRFs encoding the peripheral visual field of deaf compared to hearing participants. This was likely driven by larger facilitatory center zones of the pRF profile concentrated in the near and far periphery in the deaf group. pRF density was comparable between groups, indicating pRFs overlapped more in the deaf group. This could suggest that a coarse coding strategy underlies enhanced peripheral visual skills in deaf people. Cortical thickness was also decreased in V1 in the deaf group. These findings suggest deafness causes structural and functional plasticity at the earliest stages of visual cortex.

Lateralization of semantic processing is shaped by exposure to specific mother tongues: The case of insight problem solving by bilingual and monolingual native Hebrew speakers

Solving insight problems is a complex task found to involve coarse semantic processing in the right hemisphere when tested in English. In Hebrew, the left hemisphere (LH) may be more active in this task, due to the inter-hemispheric interaction between semantic, phonological and orthographic processing. In two Hebrew insight problems experiments, we revealed a performance advantage in the LH, in contrast to the patterns previously observed in English. A third experiment, conducted in English with early Hebrew–English bilinguals, confirmed that the LH advantage found with Hebrew speakers does not depend on specific task requirements in Hebrew. We suggest that Hebrew speakers show redundancy between the hemispheres in coarse semantic processing in handling frequent lexical ambiguities stemming from the orthographic structure in Hebrew. We further suggest that inter-hemispheric interactions between linguistic and non-linguistic processes may determine the hemisphere in which coarse coding will take place. These findings highlight the possible effect of exposure to a specific mother tongue on the lateralization of processes in the brain, and carries possible theoretical and methodological implications for cross-language studies.