Internal Representation of Task Rules by Recurrent Dynamics: The Importance of the Diversity of Neural Responses

Neural activity of behaving animals, especially in the prefrontal cortex, is highly heterogeneous, with selective responses to diverse aspects of the executed task. We propose a general model of recurrent neural networks that perform complex rule-based tasks, and we show that the diversity of neuronal responses plays a fundamental role when the behavioral responses are context-dependent. Specifically, we found that when the inner mental states encoding the task rules are represented by stable patterns of neural activity (attractors of the neural dynamics), the neurons must be selective for combinations of sensory stimuli and inner mental states. Such mixed selectivity is easily obtained by neurons that connect with random synaptic strengths both to the recurrent network and to neurons encoding sensory inputs. The number of randomly connected neurons needed to solve a task is on average only three times as large as the number of neurons needed in a network designed ad hoc. Moreover, the number of needed neurons grows only linearly with the number of task-relevant events and mental states, provided that each neuron responds to a large proportion of events (dense/distributed coding). A biologically realistic implementation of the model captures several aspects of the activity recorded from monkeys performing context-dependent tasks. Our findings explain the importance of the diversity of neural responses and provide us with simple and general principles for designing attractor neural networks that perform complex computation

Polylactic acid-lauryl functionalized nanocellulose nanocomposites: Microstructural, thermo-mechanical and gas transport properties

Thermo-mechanical and gas transport properties of polylactic acid (PLA) matrix containing various amounts (from 1 to 20 wt%) of nanocellulose esterified with lauryl chains (LNC) were investigated on solvent cast film of about 50 micron. Scanning electron microscopy indicated that, up to a filler content of 6.5 wt%, LNC was well dispersed or formed small, sub-micrometric clusters. At higher filler contents, oval aggregates in the micrometric range were detected. The addition of LNC did not change the matrix glass transition temperature and melting temperature. Concurrently, as LNC content increased, both elastic and storage moduli at room temperature exhibited a sharp decrease up to 5 wt% of filler, and a lower reduction for LCN concentration of 10\u201320 wt.%. Nanocomposites with 3 and 5 wt% of LNC showed the highest strain at break and a large amount of plastic deformation due to a strong interfacial adhesion between the PLA and filler particles. For higher LNC fractions the presence of aggregates weakened the nanocomposite leading to lower values of maximum stress and strain at break. With the addition of LNC particles, gas barrier properties of the PLA film versus deuterium, nitrogen and carbon dioxide were improved up to a critical LNC concentration of 6.5 wt%, where the gas permeability of the nanocomposite resulted to be 70% lower than that of the PLA matrix. At higher filler contents, large LNC aggregates increased the gas permeability of the nanocomposites

Subcutaneous adipose tissue classification

The developments in the technologies based on the use of autologous adipose tissue attracted attention to minor depots as possible sampling areas. Some of those depots have never been studied in detail. The present study was performed on subcutaneous adipose depots sampled in different areas with the aim of explaining their morphology, particularly as far as regards stem niches. The results demonstrated that three different types of white adipose tissue (WAT) can be differentiated on the basis of structural and ultrastructural features: deposit WAT (dWAT), structural WAT (sWAT) and fibrous WAT (fWAT). dWAT can be found essentially in large fatty depots in the abdominal area (periumbilical). In the dWAT, cells are tightly packed and linked by a weak net of isolated collagen fibers. Collagenic components are very poor, cells are large and few blood vessels are present. The deep portion appears more fibrous then the superficial one. The microcirculation is formed by thin walled capillaries with rare stem niches. Reinforcement pericyte elements are rarely evident. The sWAT is more stromal; it is located in some areas in the limbs and in the hips. The stroma is fairly well represented, with a good vascularity and adequate staminality. Cells are wrapped by a basket of collagen fibers. The fatty depots of the knees and of the trochanteric areas have quite loose meshes. The fWAT has a noteworthy fibrous component and can be found in areas where a severe mechanic stress occurs. Adipocytes have an individual thick fibrous shell. In conclusion, the present study demonstrates evident differences among subcutaneous WAT deposits, thus suggesting that in regenerative procedures based on autologous adipose tissues the sampling area should not be randomly chosen, but it should be oriented by evidence based evaluations. The structural peculiarities of the sWAT, and particularly of its microcirculation, suggest that it could represent a privileged source for regenerative procedures based on autologous adipose tissues

Fungi from symptomless strawberry plants in Switzerland

Forty symptomless strawberry plants (Fragaria ananassa Duch.) belonging to different cultivars were examined for fungal flora. All the plants had originally been imported as frigo plantlets from the same nursery. Assays were performed on frigo plantlets from one batch and on plants grown under field conditions from another batch. Fungal isolations were taken from different parts of the plants (roots, crowns, petioles, leaves, flowers and fruits). Some 40 different fungal species were isolated in all, about 20 from in frigo plantlets and 30 from field-grown plants (with some overlap). About half the fungi isolated were common fungal strawberry pathogens in Switzerland. This paper outlines the problems inherent in the large-scale import of certified planting material containing potential pathogenic fungi that are not detected by routine phytosanitary inspection

A Qualitative Methodology for Studying Parent–Child Argumentation

This chapter provides a detailed exposé of the research methodology on which the investigation of parent–child argumentation during mealtime is based. In the first part, the conceptual tools adopted for the analysis of argumentative discussions between parents and children, i.e., the pragma-dialectical ideal model of a critical discussion and the Argumentum Model of Topics, are presented. Subsequently, the process of data gathering and the procedures for the transcription of oral data are discussed. Finally, in the last part of the chapter, ethical issues and practical problems in collecting parent–child mealtime conversations present throughout the study are considered

Different renal phenotypes in related adult males with Fabry disease with the same classic genotype

BACKGROUND: Fabry disease related patients with classical mutation usually exhibit similar severe phenotype especially concerning renal manifestation. METHODS: A dry blood spot screening (DBS) and the DNA analysis has been performed in a 48-year-old man (Patient 1) because of paresthesia. RESULTS: The DBS revealed absent leukocyte \u3b1-Gal A enzyme activity while DNA analysis identified the I354K mutation. Serum creatinine and e-GFR were in normal range and also albuminuria and proteinuria were absent. The brain MRI showed ischemic lesions and a diffuse focus of gliosis in the white matter, while the echocardiogram showed a left ventricular hypertrophy. The renal biopsy performed in the case index showed a massive deposition of zebra bodies. By a familiar investigation, it was recognized that his brother (Patient 2) died 2 years before from sudden death syndrome at the age of 49. He had suffered sporadic and undiagnosed pain at the extremities, a prior cataract, bilateral neurosensorial hearing loss and left ventricular hypertrophy on Echocardiogram. His previous laboratory examinations revealed a normal serum creatinine and the absence of proteinuria. Pedigree analysis of the brothers revealed a high disease burden among family members, with an affected cousin (Patient 3) who progressed early to end-stage renal disease (ESRD) that required renal transplantation. CONCLUSIONS: Here we describe the clinical history of three adult male members of the same family with the same genotype who manifested different presentation and progression of the disease, particularly concerning the renal involvement

Multicentre Withinperson Randomised Controlled Trial of 0.5 Mm Versus 1.5 Mm Subcrestal Placement of Dental Implants With Internal Conical Connection: Five-year Post-loading Results

PURPOSE. To assess whether there are any clinical benefits to placing single dental implants either 0.5 or 1.5 mm subcrestally in healed bone crests. MATERIALS AND METHODS. Sixty partially edentulous patients at six centres requiring two single implant-supported crowns had both sites randomly allocated according to a split-mouth design to either 0.5 mm or 1.5 mm subcrestal implant placement; implants in aesthetic areas were submerged for 3 months while those in non-aesthetic areas were not. Provisional acrylic crowns were fitted and replaced with definitive metal-ceramic crowns after 2 months. Patients were followed up to 5 years after loading. Outcome measures were: crown and implant failures, complications, aesthetics assessed using the pink esthetic score (PES), peri-implant marginal bone level changes, and patient prefe-rence, recorded by blinded assessors. RESULTS. Two patients dropped out. There were no statistically significant differences in failure rate (out of 58 patients, four implants failed in the 0.5 mm group versus one in the 1.5 mm group; difference =-5.17%; 95% CI-10.87% to 0.53%; P = 0.250) or complications (out of 58 patients eight complications occurred in eight patients from the 0.5 mm group versus five complications in five patients from the 1.5 mm group (difference =-5.17%; 95% CI-14.01% to 3.67%; P = 0.453) between groups. At 5 years after loading, the mean pink aesthetic scores were 10.89 ± 2.30 and 10.79 ± 2.41 in the 0.5 and 1.5 mm groups, respecti-vely, a difference that was not statistically significant (P = 0.943). Patients from the 0.5 mm group lost on average 0.53 ± 1.43 mm peri-implant marginal bone, and those in the 1.5 mm group lost 0.31 ± 0.98 mm, a statistically significant difference (0.26 mm; 95% CI 0.05 to 0.47; P = 0.016). Patients did not prefer any depth of implant placement over the other. There were no differences in outcomes between centres. CONCLUSIONS. No clinically appreciable differences were noted when placing implants surrounded by at least 1 mm of bone 0.5 mm or 1.5 mm subcrestally. Clinicians are therefore free to choose which strategy they prefer