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