Decolorization of Basic Red 5 in aqueous solution by Advanced Oxidation Process using Fenton’s reagent

Fenton reagent was employed to decolorize the aqueous solution containing a dye (Basic Red 5). The effects of initial FeSO4 concentration, initial dye concentration and initial H2O2 concentration on the decolorization of Basic red 5 were investigated. The decolorization  efficiency increase with the rise of FeSO4 concentration  and  H2O2 concentration. However the decolonization efficiency was decreased with increase of dye concentration. The optimal operation parameters for the Fenton oxidation of Basic Red 5 were  [H2O2]0 = 25.50 mg/L and [Fe2+]0 = 20.00 mg/L for [dye]0 = 45.00 mg/L under acidic conditions at room temperature. Under these conditions, 88.71% decolorization efficiency of dye in aqueous solution was achieved after 30 min of reaction.

Reaching activity in parietal area V6A of macaque: eye influence on arm activity or retinocentric coding of reaching movements?

Parietal area V6A contains neurons modulated by the direction of gaze as well as neurons able to code the direction of arm movement. The present study was aimed to disentangle the gaze effect from the effect of reaching activity upon single V6A neurons. To this purpose, we used a visuomotor task in which the direction of arm movement remained constant while the animal changed the direction of gaze. Gaze direction modulated reach-related activity in about two-thirds of tested neurons. In several cases, modulations were not due to the eye-position signal per se, the apparent eye-position modulation being just an epiphenomenon. The real modulating factor was the location of reaching target with respect to the point gazed by the animal, that is, the retinotopic coordinates towards which the action of reaching occurred. Comparison of neural discharge of the same cell during execution of foveated and non-foveated reaching movements, performed towards the same or different spatial locations, confirmed that in a part of V6A neurons reaching activity is coded retinocentrically. In other neurons, reaching activity is coded spatially, depending on the direction of reaching movement regardless of where the animal was looking at. The majority of V6A reaching neurons use a system that encompasses both of these reference frames. These results are in line with the view of a progressive visuomotor transformation in the dorsal visual stream, that changes the frame of reference from the retinocentric one, typically used by the visual system, to the arm-centred one, typically used by the motor system

Dopamine Innervation in the Thalamus: Monkey versus Rat

We recently identified the thalamic dopaminergic system in the human and macaque monkey brains, and, based on earlier reports on the paucity of dopamine in the rat thalamus, hypothesized that this dopaminergic system was particularly developed in primates. Here we test this hypothesis using immunohistochemistry against the dopamine transporter (DAT) in adult macaque and rat brains. The extent and density of DAT-immunoreactive (-ir) axons were remarkably greater in the macaque dorsal thalamus, where the mediodorsal association nucleus and the ventral motor nuclei held the densest immunolabeling. In contrast, sparse DAT immunolabeling was present in the rat dorsal thalamus; it was mainly located in the mediodorsal, paraventricular, ventral medial, and ventral lateral nuclei. The reticular nucleus, zona incerta, and lateral habenular nucleus held numerous DAT-ir axons in both species. Ultrastructural analysis in the macaque mediodorsal nucleus revealed that thalamic interneurons are a main postsynaptic target of DAT-ir axons; this suggests that the marked expansion of the dopamine innervation in the primate in comparison to the rodent thalamus may be related to the presence of a sizable interneuron population in primates. We remark that it is important to be aware of brain species differences when using animal models of human brain disease

Weight Consistency Specifies Regularities of Macaque Cortical Networks

To what extent cortical pathways show significant weight differences and whether these differences are consistent across animals (thereby comprising robust connectivity profiles) is an important and unresolved neuroanatomical issue. Here we report a quantitative retrograde tracer analysis in the cynomolgus macaque monkey of the weight consistency of the afferents of cortical areas across brains via calculation of a weight index (fraction of labeled neurons, FLN). Injection in 8 cortical areas (3 occipital plus 5 in the other lobes) revealed a consistent pattern: small subcortical input (1.3% cumulative FLN), high local intrinsic connectivity (80% FLN), high-input form neighboring areas (15% cumulative FLN), and weak long-range corticocortical connectivity (3% cumulative FLN). Corticocortical FLN values of projections to areas V1, V2, and V4 showed heavy-tailed, lognormal distributions spanning 5 orders of magnitude that were consistent, demonstrating significant connectivity profiles. These results indicate that 1) connection weight heterogeneity plays an important role in determining cortical network specificity, 2) high investment in local projections highlights the importance of local processing, and 3) transmission of information across multiple hierarchy levels mainly involves pathways having low FLN values

Spatial Modulation of Primate Inferotemporal Responses by Eye Position

Background: A key aspect of representations for object recognition and scene analysis in the ventral visual stream is the spatial frame of reference, be it a viewer-centered, object-centered, or scene-based coordinate system. Coordinate transforms from retinocentric space to other reference frames involve combining neural visual responses with extraretinal postural information. Methodology/Principal Findings: We examined whether such spatial information is available to anterior inferotemporal (AIT) neurons in the macaque monkey by measuring the effect of eye position on responses to a set of simple 2D shapes. We report, for the first time, a significant eye position effect in over 40 % of recorded neurons with small gaze angle shifts from central fixation. Although eye position modulates responses, it does not change shape selectivity. Conclusions/Significance: These data demonstrate that spatial information is available in AIT for the representation of objects and scenes within a non-retinocentric frame of reference. More generally, the availability of spatial information in AIT calls into questions the classic dichotomy in visual processing that associates object shape processing with ventra

Tactile localization biases are modulated by gaze direction

Identifying the spatial location of touch on the skin surface is a fundamental function of our somatosensory system. Despite the fact that stimulation of even single mechanoreceptive afferent fibres is sufficient to produce clearly localised percepts, tactile localisation can be modulated also by higher-level processes such as body posture. This suggests that tactile events are coded using multiple representations using different coordinate systems. Recent reports provide evidence for systematic biases on tactile localisation task, which are thought to result from a supramodal representation of the skin surface. While the influence of non-informative vision of the body and gaze direction on tactile discrimination tasks has been extensively studied, their effects on tactile localisation tasks remain largely unexplored. To address this question, participants performed a tactile localization task on their left hand under different visual conditions by means of a mirror box; in the mirror condition a single stimulus was delivered on participants’ hand while the reflexion of the right hand was seen through the mirror; in the object condition participants looked at a box through the mirror, and in the right hand condition participants looked directly at their right hand. Participants reported the location of the tactile stimuli using a silhouette of a hand. Results showed a shift in the localization of the touches towards the tip of the fingers (distal bias) and the thumb (radial biases) across conditions. Critically, distal biases were reduced when participants looked towards the mirror compared to when they looked at their right hand suggesting that gaze direction reduces the typical proximo-distal biases in tactile localization. Moreover, vision of the hand modulates the internal configuration of points’ locations, by elongating it, in the radio-ulnar axis