Topographically localised modulation of tectal cell spatial tuning by natural scenes

Visual neurons can have their tuning properties contextually modulated by the presence of visual stimuli in the area surrounding their receptive field, especially when that stimuli contains natural features. However, stimuli presented in specific egocentric locations may have greater behavioural relevance, raising the possibility that the extent of contextual modulation may vary with position in visual space. To explore this possibility we utilised the small size and optical transparency of the larval zebrafish to describe the form and spatial arrangement of contextually modulated cells throughout an entire tectal hemisphere. We found that the spatial tuning of tectal neurons to a prey-like stimulus sharpens when the stimulus is presented in the context of a naturalistic visual scene. These neurons are confined to a spatially restricted region of the tectum and have receptive fields centred within a region of visual space in which the presence of prey preferentially triggers hunting behaviour. Our results demonstrate that circuits that support behaviourally relevant modulation of tectal neurons are not uniformly distributed. These findings add to the growing body of evidence that the tectum shows regional adaptations for behaviour.

Optimal Extracellular Matrix Niches for Neurogenesis: Identifying Glycosaminoglycan Chain Composition in the Subventricular Neurogenic Zone

In the adult mammalian brain, new neurons are generated in a restricted region called the neurogenic niche, which refers to the specific regulatory microenvironment of neural stem cells (NSCs). Among the constituents of neurogenic niches, the extracellular matrix (ECM) has emerged as a key player in NSC maintenance, proliferation, and differentiation. In particular, heparan sulfate (HS) proteoglycans are capable of regulating various growth factor signaling pathways that influence neurogenesis. In this review, we summarize our current understanding of the ECM niche in the adult subventricular zone (SVZ), with a special focus on basement membrane (BM)-like structures called fractones, and discuss how fractones, particularly their composition of glycosaminoglycans (GAGs), may influence neurogenesis.

Migrainous Infarction with Adjacent Cortical Enhancement

A 26-year old woman developed left homonymous superior quadrantanopia followed by severe pulsating headache with vomiting. Thereafter, she experienced recurrent left hemiparesis and paresthesia with or without headache. Brain magnetic resonance imaging showed diffusion restriction in the territory of the right posterior cerebral artery and contrast enhancement in the right lingual gyrus adjacent to the diffusion-restricted region. This case suggests an occurrence of cerebral infarction and blood-brain barrier disruption associated with migraine with aura.

Gauss–Newton–Secant Method for Solving Nonlinear Least Squares Problems under Generalized Lipschitz Conditions

We develop a local convergence of an iterative method for solving nonlinear least squares problems with operator decomposition under the classical and generalized Lipschitz conditions. We consider the case of both zero and nonzero residuals and determine their convergence orders. We use two types of Lipschitz conditions (center and restricted region conditions) to study the convergence of the method. Moreover, we obtain a larger radius of convergence and tighter error estimates than in previous works. Hence, we extend the applicability of this method under the same computational effort.

Unexpected Occurrence of Cladosporium spp. on the Inner Surface of the Spathe of the Titan Arum, Amorphophallus titanum

The air-borne distributed genus Cladosporium Link is globally one of the most common fungal genera. By sequencing the barcode marker ITS, here, we document two taxa belonging to this genus – C. cf. dominicanum Zalar, de Hoog & Gunde-Cimerman and C. halotolerans Zalar, de Hoog & Gunde-Cimerman ( C. sphaerospermum Penz complex) – which were detected on the inner surface of the spathe of the titan arum, Amorphophallus titanum (Becc.) Becc. (Araceae). Titan arum holds the record for the largest unbranched inflorescence in the plant kingdom, with a height reaching up to 3 meters. The two identified Cladosporium species are part of a clearly defined fungal layer inside the proximal region of the spathe, surrounding the flower-containing region of the spadix. To the best of our knowledge, this is the first record of a macroscopically visible layer of Cladosporium on a living plant material. Furthermore, this study also discusses why this layer occurs only in a spatially restricted region of the spathe, and the possible consequences that the occurrence of these fungi might have on the development and reproduction of the plant.

Relationship Between the Activities of Gloss-Selective Neurons in the Macaque Inferior Temporal Cortex and the Gloss Discrimination Behavior of the Monkey

In the macaque monkey, neurons that selectively respond to specific gloss are present in a restricted region of the central part of the inferior temporal (IT) cortex. Although the population activity of these neurons is known to represent the perceptual gloss space, the involvement of their activity in gloss perception has not been directly tested. In the present study, we examined the causal relationship between the activities of gloss-selective neurons and gloss perception by applying electrical microstimulation or injection of small amounts of muscimol (GABAA agonist) to manipulate neural activities while monkeys performed a gloss discrimination task. We found that microstimulation within or in the vicinity of the region where gloss-selective neurons were recorded induced bias toward higher gloss judgment. With muscimol injection, gloss discrimination performance was degraded in one monkey after the first injection into the region where gloss-selective neurons were recorded. These results suggest that gloss discrimination behavior is mediated by the activities of a gloss-selective network that includes the gloss-selective region in the central IT cortex examined here.

Dynamics of a delayed Lotka-Volterra model with two predators competing for one prey

<p style='text-indent:20px;'>In this paper, we study the local dynamics of a class of 3-dimensional Lotka-Volterra systems with a discrete delay. This system describes two predators competing for one prey. Firstly, linear stability and Hopf bifurcation are investigated. Then some regions of attraction for the positive steady state are obtained by means of Liapunov functional in a restricted region. Finally, sufficient and necessary conditions for the principle of competitive exclusion are obtained.</p>

A new species of Pheraeus Godman, 1900 (Hesperiidae, Hesperiini, Moncina) restricted to Rio Doce Valley, Brazil

A new species of Pheraeus Godman, 1900, P. guandu Saraiva, Carneiro, Mielke & Casagrande sp. nov., restricted to the Rio Doce Valley (Espírito Santo and Minas Gerais, southeast Brazil) is described. Adults of the new species are illustrated and compared with phenotypically closest species, Pheraeus argynnis (Plötz, 1884), together with the diagnostic characters present in the male and female genitalia. This new species is here solely described because it is known to occur in a restricted region crossed by the Rio Doce. This region has been extensively transformed in recent decades by agriculture, livestock, construction of hydroelectric and tailing dams, and more recently by a dam failure, thus potentially impacting the habitat of this species.

Extended Semilocal Convergence for the Newton- Kurchatov Method

We provide a semilocal analysis of the Newton-Kurchatov method for solving nonlinear equations involving a splitting of an operator. Iterative methods have a limited restricted region in general. A convergence of this method is presented under classical Lipschitz conditions.The novelty of our paper lies in the fact that we obtain weaker sufficient semilocal convergence criteria and tighter error estimates than in earlier works. We find a more precise location than before where the iterates lie resulting to at least as small Lipschitz constants. Moreover, no additional computations are needed than before. Finally, we give results of numerical experiments.