Search results for "SPACE"
showing 10 items of 21658 documents
Are signs of ocular tilt reaction in patients with cerebellar lesions mediated by the dentate nucleus?
2008
A sensitive clinical sign of a vestibular tone imbalance in the roll plane is the ocular tilt reaction (OTR), a combination of skew deviation, ocular torsion and head and perceptual tilts such as tilts of the subjective visual vertical (SVV). Of these OTR components tilts of SVV are the most frequent. While these signs are regularly seen in patients with unilateral brainstem lesions, only a few case studies are available on their occurrence in patients with cerebellar lesions. Thus, the question arises whether cerebellar structures may be involved in contra- and/or ipsiversive tilts of the perceived vertical and other signs of OTR. We used lesion-mapping techniques in a total of 31 patients…
Overestimation of numerical distances in the left side of space
2004
Normal subjects presented with a middle number and two left- and right-sided outer numbers overestimate the numerical distance between the middle number and that positioned at its left side. Repetitive transcranial magnetic stimulation (rTMS) of the right posterior parietal cortex specifically counteracts this bias, suggesting that the mental representation of space defined by numbers is shifted toward the left side depending on a greater activity of the right hemisphere.
Automatic numerical-spatial association in synaesthesia: An fMRI investigation
2016
A horizontal mental number line (MNL) is used to describe how quantities are represented across space. In humans, the neural correlates associated with such a representation are found in different areas of the posterior parietal cortex, especially, the intraparietal sulcus (IPS). In a phenomenon known as number-space synaesthesia, individuals visualise numbers in specific spatial locations. The experience of a MNL for number-space synaesthetes is explicit, idiosyncratic, and highly stable over time. It remains an open question whether the mechanisms underlying numerical-spatial association are shared by synaesthetes and nonsynaesthetes. We address the neural correlates of number-space assoc…
Numbers and time doubly dissociate
2011
The magnitude dimensions of number, time and space have been suggested to share some common magnitude processing, which may imply symmetric interaction among dimensions. Here we challenge these suggestions by presenting a double dissociation between two neuropsychological patients with left (JT) and right (CB) parietal lesions and selective impairment of number and time processing respectively. Both patients showed an influence of task-irrelevant number stimuli on time but not space processing. In JT otherwise preserved time processing was severely impaired in the mere presence of task-irrelevant numbers, which themselves could not be processed accurately. In CB, impaired temporal estimatio…
Parietal versus temporal lobe components in spatial cognition: Setting the mid-point of a horizontal line
2009
Recent anatomo-clinical correlation studies have extended to the superior temporal gyrus, the right hemisphere lesion sites associated with the left unilateral spatial neglect, in addition to the traditional posterior-inferior-parietal localization of the responsible lesion (supramarginal gyrus, at the temporo-parietal junction). The study aimed at teasing apart, by means of repetitive transcranial magnetic stimulation (rTMS), the contribution of the inferior parietal lobule (angular gyrus versus supramarginal gyrus) and of the superior temporal gyrus of the right hemisphere, in making judgments about the mid-point of a horizontal line, a widely used task for detecting and investigating spa…
Time and spatial attention: Effects of prism adaptation on temporal deficits in brain damaged patients
2011
Growing evidence indicates that the representations of space and time interact in the brain but the exact neural correlates of such interaction remain unknown. Neuroimaging and neuropsychological studies show that processing of temporal information engages a distributed network in the right hemisphere and suggest a link between deficits in spatial attention and deficits in time perception. In the present study we used the procedure of prismatic adaptation (PA) to directionally manipulate spatial attention in order to explore the effect of attentional deviation on time perception in patients with right (RBD) vs. left (LBD) brain damage. In a first experiment, two groups of RBD and LBD patien…
Facilitation of bottom-up feature detection following rTMS-interference of the right parietal cortex
2010
In visual search tasks the optimal strategy should utilize relevant information ignoring irrelevant one. When the information at the feature and object levels are in conflict, un-necessary processing at higher level of object shape can interfere with detection of lower level orientation feature. We explored the effects of inhibitory trains of transcranial magnetic stimulation (rTMS) on the right and left parietal cortex in healthy subjects performing two visual search tasks. One task (Task A) was characterised by an object-to-feature interference. The other task (Task B) was without such interference. We found that rTMS of the right parietal cortex significantly reduced reaction times (RTs)…
Exploring the switching of the focus of attention within working memory: A combined event-related potential and behavioral study.
2018
Abstract Working memory enables humans to maintain selected information for cognitive processes and ensures instant access to the memorized contents. Theories suggest that switching the focus of attention between items within working memory realizes the access. This is reflected in object-switching costs in response times when the item for the task processing is to be changed. Another correlate of attentional allocation in working memory is the P3a-component of the human event-related potential. The aim of this study was to demonstrate that switching of attention within working memory is a separable processing step. Participants completed a cued memory-updating task in which they were instr…
Nonlinear analysis of continuous ECG during sleep I. Reconstruction.
2000
In recent years evidence has accumulated that ECG signals are of a nonlinear nature. It has been recognized that strictly periodic cardiac rhythms are not accompanied by healthy conditions but, on the contrary, by pathological states. Therefore, the application of methods from nonlinear system theory for the analysis of ECG signals has gained increasing interest. Crucial for the application of nonlinear methods is the reconstruction (embedding) of the time series in a phase space with appropriate dimension. In this study continuous ECG signals of 12 healthy subjects recorded during different sleep stages were analysed. Proper embedding dimension was determined by application of two techniqu…
Cisternostomy for Traumatic Brain Injury: Pathophysiologic Mechanisms and Surgical Technical Notes
2016
Objective Traumatic brain injury (TBI) is one of the major challenges in health care, representing the third most frequent cause of death. Current optimal management is based on a progressive, target-driven approach combining both medical and surgical treatment strategies. Here we describe cisternostomy, an emerging surgical treatment for the treatment of TBI. Methods Cisternostomy is a novel technique that incorporates knowledge of skull base and microvascular surgery. By opening the brain cisterns to atmospheric pressure, the technique could decrease the intracranial pressure due to a backshift of the cerebrospinal fluid (CSF) from the swollen brain to the cisterns through the Virchow-Rob…