Transcript Temporal Aspects of Visual Extinction

1
Basic Anatomy
 Chris Rorden
– Coordinates
– Cortex
 Brodmann Areas
 Common Names
 Talairach Coordinates
– Best web site:
 www.anatomy.usyd.edu.au/glossary/
 www.mricro.com
2
Relative Coordinates
On the globe we talk about North, South, East
and West.
Lets explore the coordinates for the brain.
3
Multiple Choice
 Which arrow points dorsally?
A.
B.
C.
D.
E.
Red
Green
Blue
Red and Green
None of above
4
Multiple Choice
 Which arrow points dorsally?
A.
B.
C.
D.
E.
Red
Green
Blue
Red and Green
None of above
5
Orientation
 Human anatomy described
as if person is standing
 If person is lying down, we
would still say the head is
superior to feet.
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Orientation - animals
Dorsal
back
 Cranial
head
 Rostral
beak
Caudal
tail
Ventral
belly
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Coordinates – Human
 Human dorsal/ventral and rostral/caudal differ for brain and
spine.
– Head/Foot, Superior/Inferior, Anterior/Posterior not ambiguous.
Dorsal
Ventral
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Anatomy – Relative Directions
Anterior/Posterior
aka Rostral/Caudal
Posterior <> Anterior
Ventral/Dorsal
aka Inferior/Superior
aka Foot/Head
Ventral <> Dorsal
lateral < medial > lateral
Posterior <> Anterior
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Coordinates - Anatomy
3 Common Views of
Brain:
– Coronal (head on)
– Sagittal (profile)
– Axial (bird’s eye), aka
Transverse. The book
calls this ‘Horizontal’ but
it is not horizontal when
we are lying in a
scanner.
coronal
axial
sagittal
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Coronal
Corona: ‘crown’ a coronal plane is parallel to
crown that passes from ear to ear
– Coronal cut creates anterior, posterior portions
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Sagittal
Sagittal – ‘arrow like’
– Sagittal cut divides object into left
and right
– sagittal suture looks like an arrow.
top view
12
Transverse
Transverse: perpendicular to the long axis
– These cuts are also referred to as Axial.
Example:
cucumber slices
are transverse
to long axis.
13
Oblique Slices
 Slices that are not cut parallel to an orthogonal plane
are called ‘oblique’.
 The oblique blue slice is neither Coronal nor Axial.
Cor
Oblique
Ax
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Anatomy
Brain Planes
Axis of left/right plane easy to
define
What is the axis for axial plane?
?
?
?
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Bicommissural plane
 Axis for axial plane is defined by anterior commissure
(AC) and posterior commissure (PC).
 Both are small regions that are clear to see on most
scans.
 PC
 AC
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Distance from midline
– Medial – near sagittal midline
Optic chiasm C medial of eyes
– Lateral – far from sag. Midline
Eyes are lateral of optic chiasm
– Ipsilateral – same side
Damage to A will cause blindness in
ipsilateral eye
– Contralateral –different side
Damage to D will lead to a contralateral
field cut.
– Note: after brain injury (lesions) we talk
about contralesional and ipsilesional
Damage to visual cortex G leads to
problems with contralesional vision.
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Relative positions
 Distance From Body
– Proximal, Central: near center of body
 Think ‘proximity’
 Shoulders are proximal parts of arms
– Distal,peripheral: away from body
 Think distant
 Fingers are distal parts of the arms
 Distance from Surface
– Superficial, external: near surface
 The bump bruised superficial tissue.
– Profound, deep: far from surface
 The car crash injured deep organs.
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Neuron: Cell which is responsible for
receiving, transmitting and synthesizing
information
– cell body: contains organelles for metabolism and
a nucleus
Glial Cells: Support cells for Neurons
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The cortex
Cortex – ‘Bark’ shell of brain
~80% of human brain
~20% of squirrel brain
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The big folds
The folds of your brain are like a fingerprint –
there are a few general patterns, with
individual variability.
Two main folds
– Central Sulcus
Fissure of Rolando
Rolandic sulcus
– Lateral sulcus
Sylvian fissure
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Describing cortex location
Brodmann Areas (BAs, 1909)
Appearance of cortex under microscope
Not necessarily function
Arbitrary numbers are
hard to remember
22
Brodmann Areas
Function does not necessarily follow
appearance.
Some key areas:
44: Broca’s Area
22: Wernicke’s Area
17: V1 Primary Visual
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Brodmann Areas (medial slice)
Note that gray matter is located in the
longitudinal fissure (between the two
hemispheres)
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Squirrels vs humans
squirrel brain
– Surface of human brain
is grooved.
– Surface of brain from
many animals is flat.
– If we completely flattened
a squirrel brain, it would
be the size of a stamp.
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Cortical folding
Cortical folding increases surface area.
Ridges are called Gyri (singular = Gyrus)
– Greek gyros = circle, hence a coil of brain cortex
Valleys are called Sulci (singular = Sulcus).
– Latin = a groove.
Gyri
Sulci
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Anatomy
Surface of human cortex and cerebellum is
very folded
– Flattened, each hemisphere 1100cm2
– Cerebellum is also 1100cm2
Crumpled shape hides size of cortex
– Compare Folded/Unfolded (from Marty Sereno)
Human
Chimpanzee
Monkey
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Cortical Names
Much of cortex referred
to by combination of
coordinate+lobe+gyrus
E.G. Superior Temporal
Gyrus (STG)
Middle Temporal
Gyrus(MTG)
Lateral Occipital Gyrus
(LOG)
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Cortical names
Tip of an object called a ‘pole’
Frontal Pole
Temporal Pole
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Sulci names
Many of sulci referred to by combination of
coordinate+lobe+sulcus
– Superior temporal sulcus (STS)
– Inferior frontal sulcus (IFS)
– Precentral and postcentral sulci
are just anterior and posterior to
the central sulcus.
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Brain function
Anatomy is interested with
the structure of an organism.
Physiology is interested in
the function of the structure.
We are still learning about
brain function
Modern maps of brain
function are primitive…
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Brain function
Much of the primate cortex
devoted to vision.
In some monkeys, up to 50%
of neocortex is devoted to
vision.
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Brain function
 Two striking features of
human brain
1. Lots of cortex ‘left over’
(yellow)
not devoted to specific
task – we are flexible
2. Not much of the cortex is
solely devoted to
language.
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A
1
B
2
4
3
C
D