Search results for "Visual Perception"
showing 10 items of 387 documents
Visual cortex hyperexcitability in migraine in response to sound-induced flash illusions
2015
Objective: Sound-induced flash illusions depend on visual cortical excitability. In this study, we explored whether sound-induced flash illusions are perceived differently in migraine, a condition associated with pathologic cortical hyperexcitability. Methods: Sound-induced flash illusions were examined in 59 migraine patients (mean age = 32 ± 16 years; 36 females), 32 without aura and 27 with aura, and in 24 healthy controls (mean age = 42 ± 17 years; 16 females). Patients were studied during attacks and interictally. Visual stimuli (flashes) accompanied by sounds (beeps) were presented in different combinations: a single flash with multiple beeps was given to induce the perception of mult…
Visuospatial learning is fostered in migraine: evidence by a neuropsychological study
2018
Cognitive profile in migraine patients still remains undefined. Contradictory evidence has been provided, with impairments in different cognitive domains, normal cognition, or even better performance compared to healthy controls (HC). The latter is of particular interest considering the evidence of glutamatergic upregulation in migraine, particularly in the visual cortex, and the role of the glutamatergic system in synaptic plasticity and learning. The aim of our study is to compare cognitive performance for visuospatial memory and learning (supraspan modality) between migraineurs without aura (MwoA) and HC. Twenty-one subjects suffering from MwoA and 21 HC were enrolled. Migraineurs during…
Visual inference of arm movement is constrained by motor representations
2015
International audience; Several studies support the idea that motion inference is strongly motor dependent. In the present study, we address the role of biomechanical constraints in motion prediction and how this implicit knowledge can interfere in a spatial prediction task. Right-handed (RHS) and left-handed subjects (LHS) had to estimate the final position of a horizontal arm movement in which the final part of the trajectory was hidden. Our study highlighted a direction effect: end point prediction accuracy was better to infer the final position of horizontal motion directed toward the median line of human body. This finding suggests that the spatial prediction of end point is mapped ont…
Modulation of cortical motor outputs by the symbolic meaning of visual stimuli.
2010
Abstract The observation of an action modulates motor cortical outputs in specific ways, in part through mediation of the mirror neuron system. Sometimes we infer a meaning to an observed action based on integration of the actual percept with memories. Here, we conducted a series of experiments in healthy adults to investigate whether such inferred meanings can also modulate motor cortical outputs in specific ways. We show that brief observation of a neutral stimulus mimicking a hand does not significantly modulate motor cortical excitability (Study 1) although, after prolonged exposure, it can lead to a relatively nonspecific modulation (Study 2). However, when such a neutral stimulus is p…
The neuropsychology of variant CJD: a comparative study with inherited and sporadic forms of prion disease.
2005
Objective: To assess cognitive function in variant Creutzfeldt-Jakob disease (vCJD). We describe the neuropsychological profiles of 10 cases and compare these data with cross sectional data obtained from patients with histologically confirmed sporadic CJD and cases with inherited prion disease with confirmed mutations in the prion protein gene. Methods: Patients referred to the Specialist Cognitive Disorders Clinic at the National Hospital for Neurology and Neurosurgery and the National Prion Clinic at St Mary's Hospital, London for further investigation of suspected CJD were recruited into the study. The neuropsychological test battery evaluated general intelligence, visual and verbal memo…
Perceptual Correlate of Nociceptive Long-Term Potentiation (LTP) in Humans Shares the Time Course of Early-LTP
2006
As in neocortex and hippocampus, neurons in the dorsal horn of the spinal cord develop long-term potentiation of synaptic efficacy (LTP) on high-frequency stimulation (HFS) of their afferent input, although how long LTP lasts in this nociceptive relay nucleus has not yet been addressed. Here we studied neurogenic hyperalgesia, a perceptual correlate of nociceptive LTP, in 13 healthy subjects, after HFS (5 × 1 s at 100 Hz) of superficial cutaneous afferents. HFS led to a mean upward shift of the stimulus–response function for pinprick-evoked pain (punctate mechanical hyperalgesia) in all subjects by a factor of 2.5 ( P < 0.001) that lasted undiminished for the initial 1-h observation per…
Axis Rotation and Visually Induced Motion Sickness: The Role of Combined Roll, Pitch, and Yaw Motion
2011
A well-known phenomenon in aviation and in virtual environments such as simulators or computer games is motion sickness (MS). The amount of sensory conflict is thought to be responsible for the severity of MS, which should increase with the complexity of the simulated motion. The focus of the present study is on the direction and complexity of simulated body rotations in the genesis and severity of visually induced MS. The methods utilized for this study are as follows: Three simulated rollercoaster rides including translational movement in the fore-aft axis and additional rotational motion either in pitch only, along the pitch and roll axes, or in pitch, roll, and yaw were generated. The a…
Human dopamine receptor D2/D3 availability predicts amygdala reactivity to unpleasant stimuli
2009
r r Abstract: Dopamine (DA) modulates the response of the amygdala. However, the relation between dopa- minergic neurotransmission in striatal and extrastriatal brain regions and amygdala reactivity to affective stimuli has not yet been established. To address this issue, we measured DA D2/D3 receptor (DRD2/3) availability in twenty-eight healthy men (nicotine-dependent smokers and never-smokers) using positron emission tomography with ( 18 F)fallypride. In the same group of participants, amygdala response to unpleasant visual stimuli was determined using blood oxygen level-dependent (BOLD) functional mag- netic resonance imaging. The effects of DRD2/3 availability in emotion-related brain …
Differentiating the differential rotation effect.
2011
As an observer views a picture from different viewing angles, objects in the picture appear to maintain their orientation relative to the observer. For instance, the eyes of a portrait appear to follow the observer as he or she views the image from different angles. We have explored this rotation effect, often called the Mona Lisa effect. We report three experiments that used portrait photographs to test variations of the Mona Lisa effect. The first experiment introduced picture displacements relative to the observer in directions beyond the horizontal plane. The Mona Lisa effect remained robust for vertical and/or diagonal observer displacements. The experiment also included conditions in …
For the mind's eye the world is two-dimensional.
2010
The nature of visual mental images is a topic that has puzzled neuroscientists, psychologists, and philosophers alike. On the one hand, mental images might preserve the 3-D properties of our perceptual world. On the other hand, they might be akin to 2-D pictures, such as photographs, paintings, or drawings. In the present study, 16 observers judged where real objects (Experiment 1) or photographs thereof (Experiment 2) were pointing. Both experiments contained a perception condition and an imagery condition. In Experiment 1, there was a significant difference between the pointing errors in the perception and the imagery conditions, whereas there was no such difference in Experiment 2. In im…