1,721,100 research outputs found
Connectivity between ventromedial prefrontal cortex and posterior superior temporal sulcus
Full text linkThe well-articulated Self Attention Network (SAN) framework accounts for a great portion of the available evidence on neurocognitive interactions between self-bias phenomena and attention. I argue that more work is necessary to refine our understanding about the effective and functional connectivity of the different nodes of the proposed network. In particular, the nature of the control of ventro-medial prefrontal cortex over posterior superior temporal sulcus has to be worked out further. Simple excitatory connections between these two nodes, as proposed by the SAN model, do not satisfactorily account for existing neuropsychological dissociations and are not fully warranted by neuroimaging evidence
The pheromone genes of the self/non-self recognition mechanism of the ciliate Euplotes crassus generate multiple transcripts by an alternative splicing of ‘matryoshka’ introns
No full textIn ciliates, cell-type distinctive protein pheromones control a self/non-self recognition mechanism responsible for the cell switching between the vegetative and sexual stages of the life cycle. These signaling molecules are encoded by genes (pheromone genes) that in the cell somatic nucleus (macronucleus) represent the transcriptionally active versions of transcriptionally silent genes allelic at the same genetic locus mat of the cell germinal nucleus (micronucleus). In the course of evolution, in Euplotes, the native single multiallelic mat locus underwent duplication among species which, such as E. crassus, form the latest branching clade of the phylogenetic tree. Because of this duplication, E. crassus expresses two distinct families of pheromone genes instead of a single family, as is the case in species of earlier branching clades.
We analyzed the structure and expression of a number of E. crassus pheromone genes representative of the two families. Like their orthologs of other Euplotes species, these genes show 5’-leader regions that are much more extended than the coding regions, lack canonical regulatory sequences for gene transcription, and synthesize multiple transcripts (in addition to the pheromone-specific one) through the activity of two distinct transcription start sites and a mechanism of alternative intron splicing. These E. crassus introns have been found to be unique with respect to introns of all the other Euplotes pheromone genes. They can be distinguished between ‘matryoshka’ introns, residing one inside the other like Russian Dolls, and ‘non-matryoshka’ introns. While the former possess canonical GTA/TAG splicing sites, the latter possess CTA/TAC splicing sites complementary to the canonical GTA/TAG splicing sites. This strongly suggests that both the DNA strands of the E. crassus pheromone genes can be used as template for transcription. We are currently attempting to verify this hypothesis and assign a function to the products of the multiple E. crassus pheromone gene transcripts
The often overlooked coming out of ciliates: biological and experimental benefits from accepting genetically identical conspecifics as sexual partners
No full textCiliates usually manifest sex in the form of conjugation, a unique phenomenon in which cells temporarily unite two by two in mating pairs to perform a mutual exchange of gamete-nuclei derived from meiotic products of their germinal micronucleus. The native view of conjugation as a spontaneous manifestation associated with environmental famine conditions was eventually denied by the milestone Sonneborn’s finding (PNAS, 1937) that the most popular ciliate, Paramecium, actually controls conjugation through a genetic mechanism of mating types. Being only two in the Paramecium species studied by Sonneborn, these mating types were functionally equated to ‘male’ and ‘female’ sexes. And, as a consequence of this equation, conjugation was since thought of as a phenomenon committed to involve, as a rule, genetically distinct cells representing two ‘complementary’ mating types. However, this is a wrong tenet adverse the evidence that many ciliates conjugate with no discrimination between sex identity and diversity. And from this no discrimination both the ciliate biology and the students of ciliate biology draw benefit. The ciliate biology, because the homo-sexual pairs (yet ineffective to reshuffle the species gene pool) multiply the opportunity for cells to practice conjugation which, in every case, determines the initiation of a new life cycle and the replacement of the cell ‘old’ transcriptionally active somatic (macronuclear) genome with a completely new one generated from the permanently ‘young’ transcriptionally inert germinal (micronuclear) genome. The students of ciliate biology, because homo-sexual pairs form without requiring physical interactions between sexually/genetically different cells. They form as well in cultures of cells of the same identity previously suspended with filtrates from cultures of conspecific cells of different identity. Which immediately identifies species that interact sexually via water-borne mating signals (pheromones), and greatly facilitates the isolation and function-structure characterization of these signals directly from cell-culture filtrates
Concetto di specie e problemi di diagnosi tassonomica nei protozoi
No full textL'identificazione tassonomica degli organismi è di importanza vitale sia nel campo sperimentale di laboratorio sia in quello ecologico-ambientale
Neural correlates of inference-driven attention in perceptual and symbolic tasks: An event-related potential study
No full textThe inferential system anticipates the external environment by building up internal representations of its regularities. To that purpose, two sources of information are especially important and attract attentional resources: expected and unexpected events, which are useful for checking the accuracy of internal representations. In the present study, we investigated the behavioural properties and the neural mechanisms underlying the strategic allocation of attention triggered by those events. To that end, event-related potentials (ERPs) were recorded during the performance of two tasks requiring detection of predictable and unpredictable response events embedded in a visuospatial or numeric sequence. The behavioural results in the two tasks mirror each other, suggesting the recruitment of similar attentional allocation processes between the two domains. The ERPs showed partially similar effects. In both tasks, a P3a-like component signalled the capture of attention by events clashing with previous expectations, whilst a P3b-like component marked the focusing of attention on predicted events and its redistribution among all possible response events occurring after the detection of an unexpected event
The case of Air Traffic Control training
No full textAir traffic controllers have to guarantee safe and efficient air traffic by predicting future flight paths based on their perception and interpretation of multiple data on the radar display. The multi-tasking nature of their job makes the cognitive and emotional processes required in Air Traffic Control fundamentally different from those traditionally studied in the lab. Thus, Air Traffic Control represents a unique naturalistic opportunity to investigate how such a demanding job may shape cognition. This chapter reviews work dealing with the cognitive characteristics of air traffic control, as well as the few studies that have investigated how training and experience in this profession change different aspects of cognitive functioning, in particular different facets of cognitive flexibility and planning abilities. Finally, it will also examine the cognitive consequences of the unique challenges represented by man-technology interactions inherent in this job. Despite the promising findings reviewed in this chapter, the research on the cognitive enhancement derived from training and experience on ATC is still limited and not conclusive. Further methodologically well-controlled studies are clearly needed to obtain a more comprehensive picture of the extraordinary potentialities of this profession
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