Can a Common Magnitude System Theory Explain the Brain Representation of Space, Time, and Number?

Space, time, and number are important parts of our experiences and they are crucial for maintaining our behaviors in daily life. Comprehending the spatial and numerical features of our environment and perceiving and constructing the temporal framework are critical for healthy cognitive functioning and also survival. Although the problem of how these three perceptual processes work was initially studied separately, the emergence of behavioral interactions between these perceptions led to the idea that they could be run by a "common system".

Protocol to examine the neural basis of symbolic and non-symbolic quantity processing in human brain with fMRI.

Number perception is among the basic cognitive abilities necessary to understand our environment. Here, we present a protocol to examine the neural underpinnings of numerosity comparison regarding symbolic and non-symbolic stimuli using functional magnetic resonance imaging (fMRI). This protocol gives instructions for screening participants, followed by steps to perform an event-related fMRI experiment and data analysis with SPM12.

Children With Dyscalculia Show Hippocampal Hyperactivity During Symbolic Number Perception.

Dyscalculia is a learning disability affecting the acquisition of arithmetical skills in children with normal intelligence and age-appropriate education. Two hypotheses attempt to explain the main cause of dyscalculia. The first hypothesis suggests that a problem with the core mechanisms of perceiving (non-symbolic) quantities is the cause of dyscalculia (core deficit hypothesis), while the alternative hypothesis suggests that dyscalculics have problems only with the processing of numerical symbols (access deficit hypothesis).

Developmental alterations of the numerical processing networks in the brain.

Neuroimaging studies revealed that number perception is mainly located in parietal cortex. Although controversial, it was suggested that number is processed in the frontal lobe in childhood and in the parietal cortex in adulthood. The purpose of this study is to investigate developmental differences in the neural correlates of number representation with fMRI.

Amygdala-prefrontal cortex connectivity increased during face discrimination but not time perception.

Time sensitivity is affected by emotional stimuli such as fearful faces. The effect of threatening stimuli on time perception depends on numerous factors, including task type and duration range. We applied a two-interval forced-choice task using face stimuli to healthy volunteers to evaluate time perception and emotion interaction using functional magnetic resonance imaging.

Neural Mechanisms Underlying Time Perception and Reward Anticipation.

Findings suggest that the physiological mechanisms involved in the reward anticipation and time perception partially overlap. But the systematic investigation of a potential interaction between time and reward systems using neuroimaging is lacking. Eighteen healthy volunteers (all right-handed) participated in an event-related functional magnetic resonance imaging (fMRI) experiment that employs a visual paradigm that consists monetary reward to assess whether the functional neural representations of time perception and reward prospection are shared or distinct.

Neural Networks for Time Perception and Working Memory.

Time is an important concept which determines most human behaviors, however questions remain about how time is perceived and which areas of the brain are responsible for time perception. The aim of this study was to evaluate the relationship between time perception and working memory in healthy adults. Functional magnetic resonance imaging (fMRI) was used during the application of a visual paradigm.

A comparative analysis of functional connectivity data in resting and task-related conditions of the brain for disease signature of OCD.

Obsessive Compulsive Disorder (OCD) is a frequent, chronic disorder producing intrusive thoughts which results in repetitive behaviors. It is thought that this psychological disorder occurs due to abnormal functional connectivity in certain regions of the brain called Default Mode Network (DMN) mainly. Recently, functional MRI (FMRI) studies were performed in order to compare the differences in brain activity between patients with OCD and healthy individuals through different conditions of the brain.

Hemispatial neglect evaluated by visual line bisection task in schizophrenic patients and their unaffected siblings.

Visuospatial attentional asymmetry has been investigated by the line bisection task in patients with schizophrenia, however, those studies are in small number and the results are controversial. The present study aimed to investigate hemispatial neglect in patients with schizophrenia (n=30), their healthy siblings (n=30) and healthy individuals (n=24) by a computerized version of the line bisection task. Deviation from the midline for both hemispaces (mean bisection error-MBE) were calculated and the effects of both hand and line length were controlled.

Cognitive control of a simple mental image in patients with obsessive--compulsive disorder.

The nature of obsessions has led researchers to try to determine if the main problem in obsessive-compulsive disorder (OCD) is impaired inhibitory control. Previous studies report that the effort to suppress is one of the factors that increase the frequency of obsessive thoughts. Based on these results and those of the present study that suggest inferior parietal lobe (IPL) abnormality in OCD and findings of a recent study that reported the importance of the right posterior parietal cortex in cognitive control of a simple mental image, the present cognitive control paradigm study aimed to determine whether there is a difference in brain dynamics between OCD patients and non-obsessive controls while performing tasks that necessitate cognitive control of a simple mental image, and whether the right posterior parietal region is one of the regions in which a difference in activity between the OCD patients and controls would be observed.

Brain activity during landmark and line bisection tasks.

Neglect patients bisect lines far rightward of center whereas normal subjects typically bisect lines with a slight leftward bias supporting a right hemisphere bias for attention allocation. We used fMRI to assess the brain regions related to this function in normals, using two complementary tasks. In the Landmark task subjects were required to judge whether or not a presented line was bisected correctly.

How is cognitive control of a simple mental image achieved? An fMRI study.

The aim of this study was to determine the brain regions associated with suppressing the image of an object. We used functional magnetic resonance imaging (fMRI) during five mental tasks (imagining, suppressing, erasing, free thinking and resting) performed by the subjects. The analysis showed that the suppressing, erasing and imagining conditions all activated the parietal and prefrontal regions to a different extent.

Frontal and posterior ERPs related to line bisection.

The aim of this study was to investigate the dynamic nature of the cortical visuospatial attention processes during the line bisection test, which is sensitive to perceptual asymmetries. EEGs of 26 normal volunteers were recorded during the administration of a computerized line bisection test, which requires participants mark the midline of lines using a mouse. Two event-related potentials subsequent and time locked to the line presentations, namely, P300 and a positive slow wave, were obtained.

Anatomical physiology of spatial extinction.

Neurologically intact volunteers participated in a functional magnetic resonance imaging experiment that simulated the unilateral (focal) and bilateral (global) stimulations used to elicit extinction in patients with hemispatial neglect. In peristriate areas, attentional modulations were selectively sensitive to contralaterally directed attention. A higher level of mapping was observed in the intraparietal sulcus (IPS), inferior parietal lobule (IPL), and inferior frontal gyrus (IFG).

[Reliability and validity of a handedness questionnaire].

Objective: In this study, the validity and reliability of the hand preference item of a 13-item questionnaire adapted from Chapman and Chapman (1987) were investigated.

Method: This questionnaire requires subjects to indicate which hand they usually use for various actions as follows: writing, drawing, throwing, using a hammer, using a toothbrush, using an eraser on paper, using scissors, holding a match when striking it, stirring a can of paint, using a spoon, using a screwdriver, twisting off the lid of a jar, and using a knife. Each item was scored as "1" for right, "2" for either, or "3" for left, and the handedness of subjects was scored from 13 (the strongest right-hand preference) to 39 (the strongest left-hand preference).

Line bisection task performance and resting EEG alpha power.

Neurologically normal subjects generally err to the left of veridical center when performing a line bisection task, a phenomenon termed "pseudoneglect." We hypothesized that resting electroencephalogram (EEG) alpha oscillations may show relationships with attentional mechanisms and give some clues about the underlying mechanisms of pseudoneglect. We recorded resting EEGs of 41 subjects and tested them with a paper-pencil line bisection task.