Search results for "cognitive neuroscience"

Effects of different lower-limb sensory stimulation strategies on postural regulation-a Systematic review and metaanalysis

2017

Systematic reviews of balance control have tended to only focus on the effects of single lower-limb stimulation strategies, and a current limitation is the lack of comparison between different relevant stimulation strategies. The aim of this systematic review and meta-analysis was to examine evidence of effects of different lower-limb sensory stimulation strategies on postural regulation and stability. Moderate- to high-pooled effect sizes (Unbiased (Hedges' g) standardized mean differences (SMD) = 0.31-0.66) were observed with the addition of noise in a Stochastic Resonance Stimulation Strategy (SRSS), in three populations (i.e., healthy young adults, older adults, and individuals with low…

Changes in visual function and retinal structure in the progression of Alzheimer's disease

2019

Background Alzheimer's Disease (AD) can cause degeneration in the retina and optic nerve either directly, as a result of amyloid beta deposits, or secondarily, as a result of the degradation of the visual cortex. These effects raise the possibility that tracking ophthalmologic changes in the retina can be used to assess neurodegeneration in AD. This study aimed to detect retinal changes and associated functional changes in three groups of patients consisting of AD patients with mild disease, AD patients with moderate disease and healthy controls by using non-invasive psychophysical ophthalmological tests and optical coherence tomography (OCT). Methods We included 39 patients with mild AD, 2…

Naming People Ignoring Semantics in a Patient with Left Frontal Damage

1999

Studies about proper name anomia generally assume that persons' names are harder to recall than other semantic information one knows about them and that name retrieval is not possible without biographical knowledge. We describe a patient, SB, who, after a left frontal haemorrhage, was unable to recall any biographical information about people she could name. Moreover, she had a normal score in an Object Picture Naming Test, but gave confabulatory answers in a Semantic Questionnaire involving the same items. The role of frontal function in producing this pattern of impairment is discussed, together with the possible existence of a direct route from visual perception to proper name retrieval.

2016

Processing natural scenes requires the visual system to integrate local features into global object descriptions. To achieve coherent representations, the human brain uses statistical dependencies to guide weighting of local feature conjunctions. Pairwise interactions among feature detectors in early visual areas may form the early substrate of these local feature bindings. To investigate local interaction structures in visual cortex, we combined psychophysical experiments with computational modeling and natural scene analysis. We first measured contrast thresholds for 2x2 grating patch arrangements (plaids), which differed in spatial frequency composition (low, high or mixed), number of gr…

Insect brains use image interpolation mechanisms to recognise rotated objects.

2008

Recognising complex three-dimensional objects presents significant challenges to visual systems when these objects are rotated in depth. The image processing requirements for reliable individual recognition under these circumstances are computationally intensive since local features and their spatial relationships may significantly change as an object is rotated in the horizontal plane. Visual experience is known to be important in primate brains learning to recognise rotated objects, but currently it is unknown how animals with comparatively simple brains deal with the problem of reliably recognising objects when seen from different viewpoints. We show that the miniature brain of honeybees…

Neuropsychological Approaches to Visually-Induced Vection: an Overview and Evaluation of Neuroimaging and Neurophysiological Studies

2020

Abstract Moving visual stimuli can elicit the sensation of self-motion in stationary observers, a phenomenon commonly referred to as vection. Despite the long history of vection research, the neuro-cognitive processes underlying vection have only recently gained increasing attention. Various neuropsychological techniques such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) have been used to investigate the temporal and spatial characteristics of the neuro-cognitive processing during vection in healthy participants. These neuropsychological studies allow for the identification of different neuro-cognitive correlates of vection, which (a) will help to unravel …

GESTALT-INSPIRED FEATURES EXTRACTION FOR OBJECT CATEGORY RECOGNITION

2013

International audience; We propose a methodology inspired by Gestalt laws to ex- tract and combine features and we test it on the object cat- egory recognition problem. Gestalt is a psycho-visual the- ory of Perceptual Organization that aims to explain how vi- sual information is organized by our brain. We interpreted its laws of homogeneity and continuation in link with shape and color to devise new features beyond the classical proxim- ity and similarity laws. The shape of the object is analyzed based on its skeleton (good continuation) and as a measure of homogeneity, we propose self-similarity enclosed within shape computed at super-pixel level. Furthermore, we pro- pose a framework to …

Multivariate EEG spectral analysis evidences the functional link between motor and visual cortex during integrative sensorimotor tasks

2012

The identification of the networks connecting brain areas and the understanding of their role in executing complex tasks is a crucial issue in cognitive neuroscience. In this study, specific visuomotor tasks were devised to reveal the functional network underlying the cooperation process between visual and motor regions. Electroencephalography (EEG) data were recorded from twelve healthy subjects during a combined visuomotor task, which integrated precise grip motor commands with sensory visual feedback (VM). This condition was compared with control tasks involving pure motor action (M), pure visual perception (V) and visuomotor performance without feedback (V + M). Multivariate parametric …

Symmetry in Computer Vision

2002

Symmetry properties establish the invariance of a system to a given set of transformations. Physicists assign special meaning whenever symmetry is broken in nature; for example, groups of symmetry have been used to explain and predict the spatial organization of atoms in a crystal. Psychologists consider relevant the property of symmetry in the perception of visual signals. The paper will briefly describe different approaches, introduced in computer vision, to measure symmetry. A review of some applications at the Computer Vision Group (Department of Mathematics and Applications of Palermo University) is presented. They regard attentive visual processing, the analysis of faces, the recognit…

Eye movements when reading words with $YMβOL$ and NUM83R5: There is a cost

2009

Recent evidence from masked priming experiments has revealed that readers regularize letter-like symbols and letter-like numbers into their corresponding base letters with minimal processing cost. However, one open question is whether the same pattern occurs when these items are presented during normal silent reading. In the present study, we respond to this question in an eye-movement experiment that included sentences with words that had symbols and numbers as letters, as in “YESTERDAY I SAW THE SECRE74RY WORKING VERY HARD”. Results revealed that there is a greater reading cost associated with letter-by-number replacements than with letter-by-symbol replacements, especially when the repla…