Transcript Intro Lecture Powerpoint - McCausland Center For Brain Imaging

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Introduction: Traumatic Brain Injury
Chris Rorden
– Overview of course
– Motivation and Significance of Topic
– Basic terms and anatomy
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Brain function
 Brain functions are both distributed and modular.
 Modular: focal injury can lead to specific impairment.
– E.G. Lanugage deficits typically seen after left but not right hemisphere
injury.
 Distributed: large network involved
– Damage to any nodes or white matter tracts lead to eye movement
deficits.
 Knock on effects: damage to one node degrades performance
upstream.
– Damage to V1 effectively disables V2.
 Disconnection syndromes:
– Damage to white matter sufficient to disable intact cortex.
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Regeneration
 Peripheral nervous system
can exhibit profound
rehabilitation.
 In general, CNS neurons do
not regenerate, though glial
cells often do.
 Neurons can exhibit dendritic
sprouting.
 Changes in neurotransmitters
and blood flow also play a
role.
Rivers and Head ~1908
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Plasticity
 The brain is often able to compensate in response to
small injuries.
 Most rehabilitation aims to leverage this.
 Plasticity effects are age related, typically younger
individuals show better effects.
 Plasticity also changes with time. Injury and recovery
often exhibits a characteristic time course.
 Plasticity is typically a good thing, but not always.
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Types of Injury
 Focal versus Diffuse.
– Focal refers to discrete spatial extent,
for example TBI due to mechanical force
(vulnerable regions) or stroke due to
blockage (ischemic).
– Diffuse refers to widespread injury to
many regions. For example TBI due
shearing of white matter or stroke due to
bleeding (hemorrhagic).
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TBI
TBI classification remains vague.
Mild injuries much more common.
Severe
Moderate
Mild
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Classification
GCS: Glasgow Coma Scale
PTA: Post traumatic Amnesia
LOC: Loss of consciousness
Mild TBI Terms
– Complicated mTBI: injury visible in brain scan
– Postconcussion injury: long term deficits
– Concussion: mTBI ~ brain clearly injured, typically
full functional recovery. Permanent injury debated
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Immediate and long term effects of TBI
 Contusion (bruising) results in
increased cranial pressure. Brain can
herniate. Life or death situation.
 TBI also associated with latent
effects. Often symptoms get worse
with time.
 Epilepsy (recurrent seizures) can
begin months after injury.
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TBI and age
TBI most common in young and old.
Classic ‘Bathtub’ function.
Children run into things, do not attend well
Adolescents drive cars and are often addled by
testosterone.
Older individuals often fall.
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Reporting findings
 How do we describe anatomy to
others?
– We could use anatomical names, but
often hard to identify.
– We could use Brodmann’s Areas,
but this requires histology – not
suitable for invivo research.
 Both show large between-subject
variability.
 Requires anatomical coordinate
system.
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Ambiguous Coordinates
D
Rat
C
R
 Human brain rotated relative
to spine
 Ambiguous dimenstions
– Dorsal/ventral
– Rostral/caudal
V
D
 Unambiguous dimensions
Human
R
C
R
D
V
V
C
– Head/Foot
– Superior/Inferior
– Anterior/Posterior
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Anatomy – Common Terms
Posterior <> Anterior
coronal
Posterior <> Anterior
Inferior <> Superior
lateral < medial > lateral
axial
 Radiological convention: Left on right side
 Neurological convention: Left on left side
sagittal
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Brain Coordinates
 On Earth: North, South, East and West.
– 0˚N/S explicitly defined by spheres rotation (equator).
– 0˚E/W arbitrary (Greenwich by convention).
 For brain: Left/Right, Sup./Inf., Ant./Post.
– Origin of L/R explicitly defined (brain symmetry)
– Origin of S/I and A/P arbitrary.
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Coordinates - Talairach
Anterior Commissure (AC) is the origin for
neuroscience.
– We measure distance from AC
57x-67x0 means ‘right posterior middle’.
Three values: left-right, posterior-anterior, ventral-dorsal
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Recognizing the cortical lobes
 Cortical lobes: Frontal, Parietal, Occipital Temporal, Insula.
 N.B. Cerebellum and subcortical gray matter.
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The major sulci
 Postcentral easy to find: becomes intraparietal.
Precentral easy to find- attached to superior frontal.
Between these is the Central (Rolandic).
Sylvian (lateral) fissure
Interhemispheric fissure
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Major sulci
You can usually find the central suclus’ motor
hand area (omega shape on axial slice)
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Gyri and sulci
Naming of most gyri (ridges) and sulci (valleys)
follows simple pattern of position (superior,
middle, inferior) and lobe name.