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Neurological Basis of Speech
Dr. Tomer NoffMaalot Educational NetworkFeb. 1, 2012
Welcome
Neuroscience
Why are we studying neuroscience?
Better understanding
Broca- Tom
Wada
Basics
Understanding structure and function
Both can be overwhelming
Understand themes
What is a Cell?
Structure
Synthesis
Specialization
The Neuron
Specialized cells
Not just the brain
Must transmit impulse (DM pt)
Physiology vs. Pathology
Definitions and contrast
How are they studied?
Importance
The Neuron The Neuron
Organization
Some terminology:
Ganglion VS. Nucleus VS. Cortex
PNS/CNS
Outer layer of collection of neurons
Organization
Anatomy
Gyri vs. Sulci
Organization
CNS
PNS
Anatomy of the Central Nervous System:
The Central Nervous System
CNSBrainSpinal cord ~
Peripheral Nervous System
Somatic Nervous System - SNSSensory & Motor
Autonomic Nervous System - ANSSympathetic DivisionParasympathetic Division
Cranial Nerves - 12 Pair Spinal Nerves - 31 Pair ~
Terminology
Afferent - toward ◦ Sensory
Efferent - away from◦ Motor ~
Dorsal - toward the back Ventral - toward the stomach Anterior & Posterior Rostral & Caudal ~
Terminology
Dorsal -
Ventral -
In reference to the BRAIN
Anterior - Posterior -
Rostral Caudal
Inferior
Superior
Brainstem & spinal cord
Ventral - Dorsal -
Rostral
Caudal
Anterior Posterior
Superior
Inferior
Neural Axis
Neural Axis
Terminology
Medial - toward the midline Lateral - away from the midline Ipsilateral - same side Contralateral - opposite side Decussate - crossover ~
Coronal - frontal ◦ cross-section - salami - front view
Sagittal - side view hot-dog bun
Horizontal - top view ~
Planes Different views
Understanding orientations
Must Know!
Coronal Section Horizontal Section
Mid-sagittal Section
Development of the Nervous System
Embryological Origin Embryo has 3 layers◦ endoderm ---> internal organs◦ mesoderm ---> muscles & skeleton◦ ectoderm ---> nervous system & skin
Neural plate (~3 weeks)◦ sheet of cells◦ neural groove◦ folds rostral to caudal ---> tube ~
Development of N.S.
Neural tube◦ CNS develops from walls◦ as tube develops dorsal portion pinches off &
forms...
Neural crest ◦ develops into all neurons of PNS
Mesoderm◦ somites ---> vertebrae & muscles ~
Neural Tube Defects Neural tube fails to close Rostral failure◦ anencephaly
skull & brain partially or totally absentperinatal mortality
◦ Encephaloceleparts of brain protrude outside skullmental disability depends on extent ~
Neural Tube Defects: Spina Bifida Cleft spine
Caudal neural tube fails to close
Incidence◦ Spina bifida occulta 40% of Americans◦ Spina Bifida Manifesta 1 in a 1000 births
myelomeningocele: 96%meningocele: 4% ~
Neural Tube Defects: Spina Bifida
Myelomeningocele◦ protruding cyst as with meningocele◦ spinal cord / nerves in protruding sac◦ Effects paralysis, incontinence, learning disabilities
◦ 70-90% also hydrocephalus can cause severe brain damage
◦ Repaired surgically ~
Neural Tube Defects: Spina Bifida
Meningocele◦ fluid-filled meningeal cyst ◦ protrudes through unfused
vertebral arches◦ SC/nerves not in sac◦ repaired surgically ◦ less severe disability than
myelomeningocele ~
Neural Tube Defects: Prevention
Possible genetic component◦ reoccurrence in families◦ ethnic/racial relationship
Folic Acid (Folate) Deficiency ◦ 50-70% of cases preventable◦ CDC guidelines
not planning pregnancy: 400 g/day planned pregnancy: 4000 g/day under direction of health care provider ~
Stages of Cellular Activity
6 distinct stages1. Neurogenesis◦ mitosis◦ nonneural cells
neurons do not divide◦ develop into neurons or glia
glia produced throughout life ~
Stages of Cellular Activity2. Cell migration◦ to specific “brain” locations◦ along radial glia◦ later: along other neurons
3. Differentiation◦ into specific neuron types◦ by induction
influenced by surrounding cells◦ or cell-autonomous ~
Stages of Cellular Activity4. Synaptogenesis◦ formation of synapses ◦ growth of axons & dendrites
growth cones5. Neuronal cell death◦ apoptosis: programmed cell death◦ 20-80% of neurons in a region◦ genetically programmed◦ lack of neurotrophic factors ~
Stages of Cellular Activity
6. synaptic rearrangement◦ elimination of synapse◦ formation of new synapses◦ dependent on neural activity ~
Differentiation
Specialization of structures 3 primary vesicles◦ rostral end of tube◦ develops into brain
Prosencephalon ---> forebrain Mesencephalon ---> midbrain Rhombencephalon ---> hindbrain ~
Prosencephalon
Secondary vesicles form & separate◦ optic ---> retinas retina & optic nerve part of brain not PNS
◦ telencephalic ---> telencephalon◦ remainder ---> diencephalon ~
Other Primary Vesicles
Mesencephalic ---> mesencephalon◦ dorsal - tectum ◦ ventral - tegmentum◦ tube - cerebral aqueduct
Rhombencephalic◦ rostral - metencephalon◦ caudal - myelencephalon◦ tube - 4th ventricle ~
Telencephalon
Cortical areas Fiber systems Landmarks◦ Fissures /Sulci◦ Lobes◦ Gyri ~
Superior surface
Longitudinal Fissure(sulcus)
Central Lateral
FrontalParietal
Temporal
Occipital
M1S1
A1
The Meninges
Tough connective tissue Dura mater - tough outer layer Arachnoid membrane - soft middle layer Pia mater - soft inner layer, next to brain
~
Subarachnoid space
Gap between arachnoid membrane and pia mater
Filled with CSF Brain floats in CSF ~
Dura materArachnoid membrane
Subarachnoid space CSF
Pia mater
Brain
The Meninges Ventricular System
Another circulatory system for the brain 4 interconnected ventricles◦ chambers
Cerebral Spinal Fluid (CSF)manufactured in choroid plexus
Hydrocephalus - blockage of CSF flow ~
Ventricular System
L V L V
3rd
Lateral Ventricles
Third Ventricle
Fourth Ventricle
Cerebral Aqueduct
Central Canal
4th