Transcript Temporal Aspects of Visual Extinction

Chapter 1 Basic Anatomy
 Chris Rorden
– Coordinates
– Introduction to the nervous system
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Multiple choice
 What is an example of a common
mnemonic?
A. Someone with blue eyes.
B. Someone with odd eyes (one blue, one green).
C. The left hand is controlled by the right side of the
brain.
D. Kings prefer chess over football, generally
speaking.
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Mnemonics
Mnemonics: tools to aid memory
– Kings prefer chess over football generally speaking
= Kingdom, phylum, class, order, family, genus,
species.
– My very easy method, just set up nine planets =
Mercury Venus Earth Mars Jupiter Saturn Neptune
Pluto
Other methods include loci (imagine a walk
with different objects in different locations) or
rhymes (one is a bun, two is a shoe…)
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Multiple choice
 What is the symbol for Sagittarius?
A.
B.
C.
D.
The Water Carrier.
The Archer.
The Sea-goat.
The Lion.
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Sagittarius
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SLP and Neuroscience
 Speech-Language Pathology
– Study of developmental and acquired disorders of human
cognition, language and speech
– Complete neurolinguistic assessments and management
 Neuroscience
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Neurology
Neurosurgery
Neuroanatomy
Neuroradiology
Neuroembryology
Neurophysiology
Neuropathology
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The Nervous System
Central Nervous System (CNS)
– Brain + Spinal Cord
Peripheral Nervous System (PNS)
– Cranial Nerves (never enter spinal column)
– Spinal Nerves
– All nerves to muscles and sensory reception sites
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Terms for Fiber Tracts
Fiber tracts like the internet – sending
information across distances
– Bundle - a group of fibers
– Column - a pillar of fibers
– Fasciculus - a small bundle
– Funiculus - a cord; a cord of nerve fibers in a nerve
trunk
– Lemniscus - a ribbon of fibers
– Tract - a large group of fibers, a pathway
You should be familiar with primary pathways
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Organization
CNS
– Relays incoming and outgoing messages
– Integrates Information
– Higher mental functions (language, cognition)
– Regulates
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The two hemispheres
 Left hemisphere is dominant for language and
handedness
 Right hemisphere is dominant for music, emotion,
and spatial processing
 Bilateral Anatomical Symmetry
 Connected by Corpus Callosum
 Unilateral Functional Differences
 Little lateralization of function at birth
 Gradual development of specialization
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Laterality and Function
 Sensory information projects to opposite hemisphere
– Object felt in right hand, Information processed by left
hemisphere
– Pain felt in left foot, Information processed by right
hemisphere
 Motor functions are also contralateral
Sensory
Functions
Motor
Functions
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Types of Brain Tissue
Gray Matter: The neurons or cells which
have specialized neurologic functions
(motor or sensory)
White Matter: Axons which form
pathways for conducting different types
of information.
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Distinct Pathways
Connections are not random – specific.
organization of connections.
Carry information from peripheral body parts to
specific areas of the brain - project to particular
cortex (outside bark) of the brain
Each peripheral body part has a receptive area
of the brain responsible for processing or
receiving input
Example: visual cortex
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Plasticity of the Brain
Brain injury is permanent, but individuals can
show recovery.
Plasticity refers to the brain’s ability to
reorganize and modify functions and adapt to
internal and external changes
– Important for learning
– Important for rehabilitation
– Younger brains tend to be more plastic
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How do we learn about brain function?
Classically, examine deficits following brain
injury, infer that damaged brain area is
required for task.
Today, most studies of brain function utilize
neuroimaging techniques such as fMRI
(functional Magnetic Resonance Imaging) or
PET(Positron Emission Tomography) – These
studies usually focus on normal brains
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MRI scan
L
 This image is in
radiological orientation
(left is shown on right).
 Images can also be in
neurological orientation
(left on left)
 These structural scans
can show abnormalities
and injury.
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CT Scans
 CT scans use X-Rays to
see inside body.
 Excellent for bone
 Often first scan in acute
care (e.g. unconscious
patient can not tell us if
they have pacemaker,
cochlear implant, or other
contraindications to MRI).
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PET/SPECT Images
 Measures of blood flow can help
determine brain metabolism.
PET: Inject radioactively labeled
glucose.
 Note: reduced uptake in
posterior region.
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Combining anatomy and metabolism
 Anatomical scans (T2 MRI) have excellent spatial
resolution.
 Metabolic scans can identify abnormalities (e.g. tumor).
 Combining takes advantage of complementary strengths
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Relative Coordinates
On the globe we talk about North, South, East
and West.
Lets explore the coordinates for the brain.
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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
Dorsal
Rostral
Caudal
Ventral
 Cranial
head
 Rostral
beak
Caudal
tail
Ventral
belly
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Coordinates – Dorsal Ventral
 Human dorsal/ventral and rostral/caudal differ for brain and
spine.
– Head/Foot, Superior/Inferior, Anterior/Posterior not ambiguous.
Dorsal
Ventral
Superior
Inferior
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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.
R
R
C
C
R
Anterior
Posterior
C
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Anatomy – Relative Directions
Anterior/Posterior
aka Rostral/Caudal
Posterior <> Anterior
Ventral/Dorsal
aka Inferior/Superior
aka Foot/Head
Posterior <> Anterior
Ventral <> Dorsal
lateral < medial > lateral
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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
sagittal
axial
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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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Transverse
Transverse: perpendicular to the long axis
– These cuts are also referred to as Axial.
Example:
cucumber slices
are transverse
to long axis.
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Sagittal
Sagittal – ‘arrow like’
– Sagittal cut divides object into left
and right
– sagittal suture looks like an arrow.
top view
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Sagittal and Midsagittal
A Sagittal slice down the
midline is called the
‘midsagittal’ view.
midsagittal
sagittal
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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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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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Movements
Extension - Increasing
angle between two body
parts (-Flexion).
Adduction - Pulls body
part toward midline
(-Abduction)
Pronation - A rotation of
the forearm that moves
the palm from an
anterior-facing position
to a posterior-facing
position (-Supination)
Flexion
Extension
Supination
Pronation
Adduction
Abduction
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Types of cells in the brain
 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 (CNS:
oligodendrocytes, astrocytes,
ependymal cells, radial glial;
PNS : Satellite and Schwann
cells)
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Neuron Types
 Neurons come in different types – some only
communicate locally, while others have very long
axons that communicate with distant regions.
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Glial Cells
 Glial cells have crucial functions www.mult-sclerosis.org/glialcells.html
– Repair, maintenance and cleaning. They produce new myelin when it
become damaged, lay down scar tissue, and remove dead cells and
other debris.
– Physical support. They have hairlike filaments which hold the neurons
in place and allow the central nervous system to retain its structural
integrity.
– CNS development. Help migration of neurons.
– Chemical regulation. Supply chemicals such as potassium and calcium
and regulate neurotransmitter levels.
 Ten times as many glial cells as neurons
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Multiple choice
 Why is the difference between a tumor and a
cancer?
A. Cancer involves neurons, tumors involve other
cells (e.g. glial cells).
B. Tumor involves neurons, cancer involves other
cells (e.g. glial cells).
C. Tumor is due to virus, cancer is due to bacteria
D. A tumor can be benign, pre-malignant or
malignant, whereas cancer is by definition
malignant.
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Tumors
 Tumor from the Latin "swelling“
In medicine, swelling due to abnormal,
uncontrolled cell division
Brain tumors are usually due to glial cells
(gliomas).
– Glial cells more common, so higher probability of cell
becoming cancerous.
– Neuron’s usually stop dividing earlier.
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The Central Nervous System
 Telencephalon (Cerebrum)
– Cortex
– Basal Ganglia
 Diencephalon
– Thalamus
– Hypothalamus)
 Mesencephalon (Midbrain)
– Colliculi
– Substancia Nigra
 Rhombencephalon
– Cerebellum
– Pons
– Medulla
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Deep Structures
 Basal Ganglia – Initiates movements
– Caudate nucleus, Putamen,Globus
pallidus
 Diencephalon
– Thalamus: Relay from body to cortex
– Hypothalamus and pituitary gland:
Regulation (e.g. hormone secretion)
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Deep Structures
 Basal Ganglia – Initiates movements
– Caudate nucleus(red)
– Putamen (green)
– Globus pallidus (blue)
 Diencephalon
– Thalamus: (yellow)
– Hypothalamus: (not shown)
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Brain Stem
 Midbrain
– Early auditory/visual
processing
– Dopamine for movement
control
– CN III and IV emerge
 Pons
– CN V, VI, VII VIII
 Medulla Oblongata
– Pyramidal decussation:
nerves from left cross to
right side and vise versa
– CN IX, X, XI, XII
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The cortex
Cortex – ‘Bark’ shell of brain – mostly gray matter
~80% of human brain
~20% of squirrel brain
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Multiple choice
 What does ‘temporal’ usually refer to?
A.
B.
C.
D.
Space.
Color.
Time.
Loudness.
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Multiple choice
 Why is it called the temporal lobe?
A. This area handles memory – remembering
previous times.
B. This lobe processes hearing – hearing requires
good temporal precision.
C. This lobe is under the temples, where the hair
turns gray early in life.
D. This area helps with counting –which we use for
timing events.
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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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Gray and White Matter
The outer surface of the cortex is gray matter:
lots of interconnected neurons (like cities)
Underneath is the white matter – the highways
connecting regions.
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Functional Classifications
 Some neurons transmit general information
– Pain and Temperature
– Originate in surface structures
 Other neurons transmit specialized information
– Specialized receptors
– Hearing and vision
 Somatic: Skeletal muscles
 Visceral: Refer to internal vital body organs
 Can be either
– Afferent: Sensory
– Efferent: Motor
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Cortical layers
 Neurons are in six layers
I. Molecular layer
II. External granular layer
III. External pyramidal layer
IV. Internal granular layer
V.Internal pyramidal layer
VI. Fusiform layer
 Functions
– Superficial layers (I-III): inter-cortical
connections
– IV: input from thalamus
– V,VI: outputs to leave cortex
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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
 Some are crucial for a
speech pathologist:
– 44 Broca’s Area
– 22 Wernicke’s Area
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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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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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