Cue-locked lateralized components in a tactile spatial attention task: Evidence for a functional dissociation between ADAN and LSN

ERP studies investigating the control processes responsible for spatial orienting in touch have consistently observed that the anterior directing attention negativity (ADAN) elicited by an attention-directing cue is followed by a sustained negativity contralateral to the cued hand. Recent evidence suggested that the later negativity, labeled late somatotopic negativity (LSN), might reflect distinct neurocognitive processes from those associated with the ADAN. To investigate the functional meaning of the ADAN and LSN components, we measured ERPs elicited by bilateral tactile cues indicating to covertly shift tactile attention to the left or right hand. Participants performed two spatial attention tasks that differed only for the difficulty of the target/nontarget discrimination at attended locations. The LSN but not the ADAN was sensitive to our experimental manipulation of task difficulty, suggesting that this component might reflect sensory-specific preparatory processes prior to a forthcoming tactile stimulus

Age effects in mental rotation are due to the use of a different strategy

Older participants are slower than younger individuals in rotating objects in their minds. One possible explanation for this age effect in mental rotation (MR) relies on the different strategies used. To explore this possiblity, in the present study, younger and older participants were assessed with two MR tasks with three- (Exp.1) and two-dimensional objects (Exp.2)with different complexity levels. In both experiments, the performance of the two age groups was comparable in simple objects. However, systematic differences were observed between the MR rates of younger and older adults while processing complex objects. Younger participants were faster in processing complex than simple objects, whereas older participants were slower in rotating complex as compared to simple objects. These results revealed that different strategies were selected by the two age groups when rotating complex objects. A simplified representation of the objects was transformed by younger participants, while older participants rotated the objects piece-by-piece

Hands behind your back: effects of arm posture on tactile attention in the space behind the body

Previous research has shown that tactile-spatial information originating from the front of the body is remapped from an anatomical to an external-spatial coordinate system, guided by the availability of visual information early in development. Comparably little is known about regions of space for which visual information is not typically available, such as the space behind the body. This study tests for the first time the electrophysiological correlates of the effects of proprioceptive information on tactile-attentional mechanisms in the space behind the back. Observers were blindfolded and tactually cued to detect infrequent tactile targets on either their left or right hand and to respond to them either vocally or with index finger movements. We measured event-related potentials (ERPs) to tactile probes on the hands in order to explore tactile-spatial attention when the hands were either held close together or far apart behind the observer's back. Results show systematic effects of arm posture on tactile-spatial attention different from those previously found for front space. While attentional selection is typically more effective for hands placed far apart than close together in front space, we found that selection occurred more rapidly for close than far hands behind the back, during both covert attention and movement preparation tasks. This suggests that proprioceptive space may ‘wrap’ around the body, following the hands as they extend horizontally from the front body midline to the centre of the back

Dopamine, affordance and active inference.

The role of dopamine in behaviour and decision-making is often cast in terms of reinforcement learning and optimal decision theory. Here, we present an alternative view that frames the physiology of dopamine in terms of Bayes-optimal behaviour. In this account, dopamine controls the precision or salience of (external or internal) cues that engender action. In other words, dopamine balances bottom-up sensory information and top-down prior beliefs when making hierarchical inferences (predictions) about cues that have affordance. In this paper, we focus on the consequences of changing tonic levels of dopamine firing using simulations of cued sequential movements. Crucially, the predictions driving movements are based upon a hierarchical generative model that infers the context in which movements are made. This means that we can confuse agents by changing the context (order) in which cues are presented. These simulations provide a (Bayes-optimal) model of contextual uncertainty and set switching that can be quantified in terms of behavioural and electrophysiological responses. Furthermore, one can simulate dopaminergic lesions (by changing the precision of prediction errors) to produce pathological behaviours that are reminiscent of those seen in neurological disorders such as Parkinson's disease. We use these simulations to demonstrate how a single functional role for dopamine at the synaptic level can manifest in different ways at the behavioural level

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

The Coupling of Alternative Splicing and Nonsense-Mediated mRNA Decay

Most human genes exhibit alternative splicing, but not all alternatively spliced transcripts produce functional proteins. Computational and experimental results indicate that a substantial fraction of alternative splicing events in humans result in mRNA isoforms that harbor a premature termination codon (PTC). These transcripts are predicted to be degraded by the nonsense-mediated mRNA decay (NMD) pathway. One explanation for the abundance of PTC-containing isoforms is that they represent splicing errors that are identified and degraded by the NMD pathway. Another potential explanation for this startling observation is that cells may link alternative splicing and NMD to regulate the abundance of mRNA transcripts. This mechanism, which we call "Regulated Unproductive Splicing and Translation" (RUST), has been experimentally shown to regulate expression of a wide variety of genes in many organisms from yeast to human. It is frequently employed for autoregulation of proteins that affect the splicing process itself. Thus, alternative splicing and NMD act together to play an important role in regulating gene expression

Urban Green Spaces and Their Role in Responding to the Heat Island Effect in Historical Urban Context

Urban vegetation is a proven and natural solution for cooling cities and providing comfort, clean air, and social, health, and economic benefits. Among many ecosystem services (ES), urban vegetation plays a major role in protecting biodiversity and providing passive thermal comfort conditions. Urban parameters, such as urban typology, building materials, and density interact with urban vegetation, which influences the microclimate of the built urban environment. The multiple services offered by urban vegetation are lessened because of the urban heat island (UHI), an extensive phenomenon caused by urbanization, which leads to higher air temperatures in urban centers. This occurs because of the prevalence of low-albedo surfaces, construction materials with high thermal capacity, and a lack of transpiring vegetation, which results in greater absorption of solar radiation. Heat accumulates and causes an increase in air temperature. While dense and large urban green areas have several effects on their surroundings, the extent to which vegetation lowers local temperatures has not been quantified yet, especially in future weather. This paper presents a microclimatic evaluation of two green areas in the city centers of two dense and compact cities in Italy. The evaluation will compare the current situation with a projected future scenario (2050). Air temperature, wind speed, mean radiant temperature (MRT), and the physiologically equivalent temperature (PET) are simulated using ENVI-met to investigate the current and future role of urban green spaces in mitigating the urban heat island effect