COGNITIVE NEUROSCIENCE

Cognitive Subtraction in Functional Imaging Research

What is functional Magnetic Resonance Imaging (fMRI

Functional Magnetic Resonance Imaging or fMRI is a non-invasive brain imaging technique which captures images of brain areas that are active at a given time due different kinds of physical sensation such as sound sight , smell , touch , and taste (What is Functional Magnetic Resonance Imaging or FMRI . It measures the small metaolic changes that occur when a part of the brain is active . It is used as a brain mapping tool in cognitive science . It provides the means to

observe mental processes

There are basic processes involved in functional Magnetic Resonance Imaging (Atherton Bart , 2001 . The two types of images that fMRI produces are functional and anatomical which depends on the type of molecules the signals are coming from . Functional scans measure oxygen amount change in the blood over time and generate images of areas with the greatest oxygen consumption , while anatomical scans measure bone and soft tissue signals which produce images similar to x-rays (Atherton Bart , 2001 . The assumption in fMRI is that the areas that used up the most oxygen are the most neurally active . The functional images are placed on top of anatomical images so that the specific brain areas can be identified . Computer software will then be used to create images that are three-dimensional

Functional Magnetic Resonance Imaging aside from its important role in scientific research has other uses . Physicians use fMRI to observe the anatomy of the brain , to monitor the function and growth of brain tumors , to guide the preparation for brain treatments which require surgery , and to assess the effects of trauma , stroke or degenerative diseases on brain functions (Radiological Society of North America 2007 . It is also used in brain mapping where areas of the brain related to the functions of speech , thought , sensation , and movement are determined

What is the Method of Cognitive Subtraction in fMRI

Functional Magnetic Resonance Imaging (fMRI ) research has two fundamental design paradigms (Functional Imaging of Neurocognition 2000 . These design paradigms include block and event-related . The two tasks selected in the block design are experimental task and control task . To come up with the cognitive component that is used in observation , a process called cognitive subtraction is used . Cognitive subtraction is the process of calculating the difference between the experimental task and the control task . It seeks activation differences between two tasks

Blocked designs are favored in experiments if the experiments aim to address cognitive processes with certain conditions . The cognitive process should be a phenomenon which could not be subjected to parametric manipulation , homogenous in its ideas where there are no correct or incorrect trials , and could not be separated from other cognitive processes by several seconds in time (Functional Imaging of Neurocognition , 2000

In studies using cognitive subtraction , both the experimental condition and the control condition which may be images of interest to the subject or person being studied , will be shown to the person in alternate time blocks . Time blocks may...