الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Functional MRI of the brain is a non-invasive way to assess brain function
using MRI signal changes associated with functional brain activity. The
most widely used method is based on blood oxygenation level dependent signal
change that is due to the hemodynamic and metabolic sequelae of neuronal responses.
Functional MRI brain mapping has been used in research as well as clinical
situations for many purposes. It can help provide basic information about
brain disease, determine, guide treatment and monitor outcomes.
The goal of fMRI data analysis is to detect correlations between brain activation
and a task the subject performs during the scan. It also aims to discover
correlations with the specific cognitive states, such as memory and recognition
induced in the subject.
A number of fMRI experiments with different tasks were conducted to
investigate brain activation among patients with language and speech disorders.
Functional MRI has been used to demonstrate the failure of autistic individuals
to recruit the cortical substrate (which include the fusiform gyrus) used for face
processing by normal subjects, providing an anatomic basis for interpreting the
lack of affect that such subjects demonstrate when confronted with human faces.
Event-related fMRI experiments were used to investigate brain activation
during speech production among stutterers. Functional MRI demonstrated that
stuttering therapy produced more widespread brain activation. Functional MRI
is feasible for evaluating language function in aphasic patients. Remote effect of focal lesion and functional redistribution or reorganization can be found in
aphasic patients.
Functional MRI demonstrated the recruitment of auditory cortex in the
deaf for the processing of purely visual stimuli. In ADHD, meta-analyses of
fMRI studies report consistent underactivation relative in the right, left ventrolateral
prefrontal cortex, anterior insula, the anterior cingulate cortex, posterior
cingulate cortex, lateral prefrontal cortex, left precuneus and thalamus.
Functional MRI studies of overt language production showed the ability
to monitor task performance as it provides information to aid in analyzing and
understanding the aphasic patient’s brain activation, as well as an additional factor
with which to characterize rehabilitation outcome.
Functional MRI studies in dyslexia have revealed a characteristic network
of posterior brain areas typically involved in reading and reading-related tasks
in children and adults including the dorsal or temporoparietal circuit and the
ventral or occipitotemporal circuit .Dyslexic readers showed relative underactivation
in posterior regions (Wernicke’s area, the angular gyrus, and striate cortex)
and relative overactivation in an anterior region (inferior frontal gyrus).
Functional MRI observed activity in the brain areas during phonation
those are specialized for different functions. More specifically, MFG and IFG
are responsible for the vocal motor planning. Furthermore, IFG is a key region
involved in laryngeal motor control of vocal pitch modulation. MTG and STG
are responsible for vocal self monitoring and voice processing, respectively.
STG is involved in sensorimotor integration for vocal production.