Transcript Automatic Gait Recognition

Structural MRI analysis of the brains of
patients with dyslexia and autism
Computer Vision and Image
Processing Lab
(CVIP)
Noha El-Zehiry
Manuel Casanova
Hossam Hassan
Aly Farag
Outlines
 Introduction
 Problem Description and Motivation
 Autism and Dyslexia (Macroscopic View)
 Basic unit of the brain (Cellular View)
 Previous studies
 Proposed approach
 Preliminary results
1. Introduction
• Dyslexia and autism represent two of the most
important disorders in the category of brain
developmental disorders.
• Pathological studies tried to investigate the changes
that occurs in the brain in each disease.
• Researches in image processing, that aim at
quantifying and discriminating between different
disease using non invasive imaging tools, are currently
in progress.
2. Problem Description and
Motivation
Autism
Autism is a brain disorder that typically affects
a person's ability to communicate and respond
appropriately to the environment.
Autism Symptoms
• most children with autism seem to have tremendous
difficulty learning to engage in the give-and-take of
everyday human interaction.
• They seem to prefer being alone.
• Some people with autism are relatively highfunctioning, with speech and intelligence intact
• Others are mentally retarded, mute, or have serious
language delays
How autism affects the patient behavior
• Communications
 Avoid eye contact
 Seem deaf
 Start developing language, then abruptly stop talking
altogether
• Social Relationships
 Act as if unaware of the coming and going of others
 Physically attack and injure others without provocation
 Inaccessible, as if in a shell
• Exploration of environment
 Remain fixated on a single item or activity
 Sniff or lick toys
 Show no sensitivity to burns or bruises, and engage in selfmutilation, such as eye gouging
 Practice strange actions like rocking or hand-flapping
Anatomy of Autistic Brains
Autism affects the following brain parts;
White matter and Gray
matter volumes
• Increment in the volume
in the white matter and
gray matter has been
observed.
The limbic system
• Decreased Hippocampus
• Increased amygdala
Hippocampus
Corpus callosum
• Reduction in corpus
callosum size
Corpus Callosum
Dyslexia
• Dyslexia is a brain-based type of learning disability
that specifically impairs a person's ability to read.
• A person who is dyslexic has trouble learning to
read, even though they are of average intelligence
and receive traditional instruction.
• A person with dyslexia has difficulty with
phonological processing and/or rapid visual-verbal
responding.
Symptoms
Dyslexic children;
• Talk later than most of the children.
• Have pronunciation problems.
• Are slow to add new vocabulary words and unable to
recall the right word.
• Confusion over the direction letters face (b/d, p/9,
p/q)
• Missing out words when reading.
• Poor handwriting
The basic unit of the brain
(Neuron Versus Minicolumn)
The Neuron
• The human brain contains
about 10 billion neurons.
• Each neuron is connected
to the other neurons through
about 10000 synapses.
Structure of the neuron
However, still the question, does
the neuron represent the basic
unit of the brain? Is it the neuron
level which is responsible for the
parallel processing and the highly
efficient computing performed by
the brain????
Communication between two neurons
What is meant by the basic unit??
What we mean by the basic unit is;
The unit that participates in the enlargement of the
brain in the development stage, and causes the
shrinkage of the brain in the aging stage.
The Minicolum:
• The minicolumn is a vertical
arrangement of neurons that grows
in the cortical surface.
• Researchers believe that
 enlargement of the cortical surface
occurs through the addition of
minicolumns rather than single
neurons.
 The effective unit of operation in
the brain is not a single neuron and
its axon, but a group of cells with
similar functional properties and
anatomical connections [2]
Minicolumns according to cell
soma arrays in planum temporale
at various ages [1]
Thinking in the sense of minicolumnar brain
structure
• The study aims at analyzing two developmental
disorders.
• Previous studies identified the minicolumn as the
basic brain unit that affects the development and
aging of the brain.
• Any malfunction in the minicolumns may be highly
related to the diseases of interest.
Thus, our main concern in this research is to investigate the
changes in the minicolumns in each disorders and correlate these
changes to the MRI findings. In this manner, we can develop an
image analysis technique to quantify these changes so as to
differentiate between different developmental disorders.
• Postmortem studies have
shown that a common feature to
both disorders is a disturbance
in the minicolumns.
• Studies indicate that dyslexia
and autism exist as opposite tail
– ends within the normal
distribution of the minicolumnar
width.
Relative Frequency
How the minicolumns differ from normal brain to
dyslexic or autistic brains
Width of the minicolumns
Distribution of the minicolumn with in normal, autistic
and dyslexic brains
How the minicolumns differ from normal brain to dyslexic or
autistic brains (cont.)
• Small minicolumnar width Ξ large number of minicolumns
• Large minicolumnar width Ξ small number of minicolumns
• Pathologically, it has been proved that, dyslexic brain has a less
number of minicolumns than normals and the converse is true in the
autistic brains.
• In the normal brain, minicolumnar interconnectivity is on the order of
1000.
• Addition of one minicolumn means increasing the number of
connections by 1000, to enable this minicolmn to communicate to all
other minicolumns.
How to correlate this pathological information to the
image analysis
• Minicolumns grow in the gray matter and communicate through the
white matter.
• Thus, according to the previous discussion of the interconnectivity,
increasing the number of minicolumns is associated with a
noticeable increment in the volume of the white matter and vice
versa.
• The increment in the volume is expected to be in the white matter
region that is closed to the gray matter.
• Dyslexia and autism are in opposite ends from pathological point of
view and it is expected that they will show opposite MRI findings, as
well.
To conclude;
The major objective of this study is to correlate
the pathological findings to the MRI findings
via quantification of the differences between
normal brains and dyslexic brains by
volumetric measures.
3. Previous studies
Herbert et al. 2004
• Herbert et al. [3] conducted a study to investigate
the volumetric differences between normal brains
and patients of autism and developmental language
disorder.
• They proved that volume of the white matter in the
autistic brain is much larger that its corresponding
values in normal brains.
• For the sake of comparison, we are trying to follow
the same methodolgies they used in their study to
prove the converse for the dyslexic patients.
4. Proposed Approach
The proposed approach consists of four major
steps;
•
•
•
•
Skull Stripping
MRI Segmentation
White Matter Parcellation
Volumetric Measures.
A block diagram of the proposed system
Skull Stripping
 Skull stripping is applied on the slices to remove
the noise artifacts represented by the non brain
tissue such as eyes, skin and fats. Background
removal will also be performed as a preprocessing
step.
Segmentation
• CVIP lab has already developed different
segmentation approaches such as level sets and
statistical approach segmentation.
• The developed algorithms are used to segment the
white matter and gray matter
White Matter Parcellation
• The white matter will be subdivided into inner and
outer compartments.
• The outer contour of the cortical surface is moved
inwards for a certain distance, then the moved
contour will represent the boundary between the
inner and outer compartements.
• This task is performed as follows;
 Morphological dilation is applied to the segmented gray
matter to bridge the gaps.
 Region filling is applied to fill the gaps.
 The signed distance function will be calculated, then the
outer contour will be pushed inwards to the required
distance.
Volumetric Measures
• Volumes of the segmented regions will be
calculated.
• Tests of hypotheses will be performed for the sake
of differentiating between normal controls and
patients
5. Preliminary Results
Slice number 45 before the skull stripping
process
Slice number 45 after the skull stripping
process
Skull Stripping Results
Original MRI slice
Segmented White Matter
Segmented Matter
Segmentation Results
Parcellation Results of synthetic image
The original contour
The final boundary
Signed Distance Map in 2D
Signed Distance Map in 3D
Parcellation Results of real data
The original contour
The final boundary
Signed Distance Map in 2D
Signed Distance Map in 3D
References
[1] D. Buxhoeveden and M. Casanova, “ The Minicolumn and Evolution
of the Brain: A Review,” Brain, Behavior and Evolution, Jul 2002.
[2] V. Mountcastle, “The columnar organization of neocortex,” Brain,
Vol.120, 1997.
[3] M. Herbert, D. Ziegler, N. Markis, “Localization of White Matter
Increase in Autism and Developmental Language Disorder,” Ann
Neurol, 2004.