Transcript Temporal Aspects of Visual Extinction

CNS Basic Anatomy
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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
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Neuroscience
• 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)
– Spinal Nerves
– Cranial 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
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–
–
–
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
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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
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Bilateral Anatomical Symmetry
Connected by Corpus Callosum
Unilateral Functional Differences
Little lateralization of function at birth
Gradual development of specialization
• Left hemisphere is dominant for language and
handedness
• Right hemisphere is dominant for music,
emotion, and spatial processing
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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
Dorsal
Ventral
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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
Anterior
C
C
R
Posterior
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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
coronal
sagittal
• 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.
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
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
• Glial cells involved with many tumours (gliomas)
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The Central Nervous System
• Telencephalon
(Cerebrum)
– Cortex
– Basal Ganglia
• Diencephalon
– Thalamus
– Hypothalamus)
• Mesencephalon
(Midbrain)
• 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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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): intercortical 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+gyr
us
• E.G. Superior
Temporal Gyrus
(STG)
• Middle Temporal
Gyrus(MTG)
• Lateral Occipital
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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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