Early Spatio-Temporal and Cognitive Deficits in Alzheimer's Disease.

Mental representation of spatial information relies on egocentric (body-based) and allocentric (environment-based) frames of reference. Research showed that spatial memory deteriorates as Alzheimer's disease (AD) progresses and that allocentric spatial memory is among the earliest impaired areas. Most studies have been conducted in static situations despite the dynamic nature of real-world spatial processing.

Social Context and Tool Use Can Modulate Interpersonal Comfort Space.

Recent research has investigated whether the representation of space around the body, in terms of reach-action (imagining of reaching another person) and comfort-social (tolerance of the other's proximity) spaces, may reflect a shared sensorimotor basis. Some studies exploiting motor plasticity induced by tool use have not observed sensorimotor identity (i.e.

Interaction with Virtual Humans and Effect of Emotional Expressions: Anger Matters!

Today we are experiencing a hybrid real-virtual society in which the interaction with virtual humans is normal and "quasi-social". Understanding the way we react to the interaction with virtual agents and the impact of emotions on social dynamics in the virtual world is fundamental. Therefore, in this study we investigated the implicit effect of emotional information by adopting a perceptual discrimination task.

The Role of Temporal Order in Egocentric and Allocentric Spatial Representations.

Several studies have shown that spatial information is encoded using two types of reference systems: egocentric (body-based) and/or allocentric (environment-based). However, most studies have been conducted in static situations, neglecting the fact that when we explore the environment, the objects closest to us are also those we encounter first, while those we encounter later are usually those closest to other environmental objects/elements. In this study, participants were shown with two stimuli on a computer screen, each depicting a different geometric object, placed at different distances from them and an external reference (i.

Defensive functions provoke similar psychophysiological reactions in reaching and comfort spaces.

The space around the body crucially serves a variety of functions, first and foremost, preserving one's own safety and avoiding injury. Recent research has shown that emotional information, in particular threatening facial expressions, affects the regulation of peripersonal-reaching space (PPS, for action with objects) and interpersonal-comfort space (IPS, for social interaction). Here we explored if emotional facial expressions may similarly or differently affect both spaces in terms of psychophysiological reactions (cardiac inter-beat intervals: IBIs, i.

Egocentric and allocentric spatial representations in a patient with Bálint-like syndrome: A single-case study.

Previous studies suggested that egocentric and allocentric spatial representations are supported by neural networks in the occipito-parietal (dorsal) and occipito-temporal (ventral) streams, respectively. The present study aimed to explore the integrity of ego- and allo-centric spatial representations in a patient (GP) who presented bilateral occipito-parietal damage consistent with the picture of a Bálint-like syndrome. GP and healthy controls were asked to provide memory-based spatial judgments on triads of objects after a short (1.

The Effect of Body-Related Stimuli on Mental Rotation in Children, Young and Elderly Adults.

This study aimed to explore the development of mental rotation ability throughout life by comparing different kinds of stimuli. Thirty-six children (6-9 years-old), 30 young (20-28 years-old) and 30 elderly people (60-82 years-old) performed mental rotation tasks with abstract (i.e.

The experience of virtual reality: are individual differences in mental imagery associated with sense of presence?

The concept of "presence" describes the quality of subjective experience in immersive virtual reality (IVR). Presence refers to a specific state of consciousness: we behave and feel as if we actually were in the virtual world even though we know there is nothing there. In their handbook of Virtual Reality, Burdea and Coiffet (Virtual reality technology, Wiley, New York, 2003) suggested that the experience of presence in IVR would emerge from the combination of three Is: Immersion or capacity to isolate from the external world, Interaction or capacity to naturally exploring the virtual environment, and Imagination or individual aptitudes with mental imagery.

The effect of facial expressions on peripersonal and interpersonal spaces.

Identifying individuals' intent through the emotional valence conveyed by their facial expression influences our capacity to approach-avoid these individuals during social interactions. Here, we explore if and how the emotional valence of others' facial expressiveness modulates peripersonal-action and interpersonal-social spaces. Through Immersive Virtual Reality, participants determined reachability-distance (for peripersonal space) and comfort-distance (for interpersonal space) from male/female virtual confederates exhibiting happy, angry and neutral facial expressions while being approached by (passive-approach) or walking toward (active-approach) them.

Phosphorylation of the insulin receptor by a casein kinase I-like enzyme.

A serine protein kinase that phosphorylates the beta-subunit of the insulin receptor has been partially purified 5,000-fold from HeLa cell membranes. The enzyme has been purified by ion-exchange and hydroxylapatite chromatography and sucrose gradient centrifugation; it has an apparent molecular weight of 36,000-43,000 daltons. It exhibits the following properties: (a) it catalyzes the phosphorylation of the autophosphorylated insulin receptor more efficiently than the nonautophosphorylated insulin receptor, (b) it decreases insulin receptor phosphorylation of tubulin but has no effect on insulin receptor phosphorylation of microtubule-associated proteins or reduced and carboxyamidomethylated lysozyme.

Opposing effects of calcium entry and phorbol esters on fusion of chick muscle cells.

Studies utilizing cultured muscle cells have shown that myoblast fusion requires extracellular Ca2+ and involves transient coordinated changes in cell membrane topography and cytoskeletal organization. However, neither the mechanisms by which Ca2+ influences these changes nor its cellular sites of action are known. We have investigated the effects of Ca2+ channel modulators and phorbol esters on fusion of embryonic chick myoblasts in culture.

Induction of phosphorylation and cell surface redistribution of acetylcholine receptors by phorbol ester and carbamylcholine in cultured chick muscle cells.

We have investigated the mechanisms regulating the clustering of nicotinic acetylcholine receptor (AChR) on the surface of cultured embryonic chick muscle cells. Treatment of these cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of protein kinase C, was found to cause a rapid dispersal of AChR clusters, as monitored by fluorescence microscopy of cells labeled with tetramethylrhodamine-conjugated alpha-bungarotoxin. The loss of AChR clusters was not accompanied by an appreciable change in the amount of AChR on the surface of these cells, as measured by the specific binding of [125I]Bgt.

Phosphorylation and assembly of nicotinic acetylcholine receptor subunits in cultured chick muscle cells.

The assembly of the nicotinic acetylcholine receptor (AChR), an oligomeric cell surface protein, was studied in cultured muscle cells. To measure this process, the incorporation of metabolically labeled alpha-subunit into oligomeric AChR was monitored in pulse-chase experiments, either by the shift of this subunit from the unassembled (5 S) to the assembled (9 S) position in sucrose density gradients, or by its coprecipitation with antisera specific for the delta-subunit. We have found that AChR assembly is initiated 15-30 min after subunit biosynthesis and is completed within the next 60 min.