Download • The neuron is similar to other cells: •Cell body: lipid bilayer

1. Overview of the Nervous System: The Neuron
• The neuron is similar to other cells:
•Cell body: lipid bilayer membrane
•Organelles: nucleus, mitochondria, etc.
• The neuron differs from other cells:
•Unique morphology: dendrites, axons
•Electrically excitable: action potential
2. Overview of the Nervous System: The Neuron
Dendrites: Receive signals
from other neurons (input)
Axons: Send signals to other
neurons (output)
Potential (mV)
action potential
50
0
-50
-65
resting potential
0
1
2
Time (ms)
3. Overview of the Nervous System: Neurons
Morphological Variation
4. Overview of the Nervous System: Golgi-Stained Pyramidal and Stellate Neurons
Cortical Pyramidal Cell
Cortical Stellate Cell
50 !m
Source: Churchill et al. (2004) BMC Neuroscience 5:43.
5. Overview of the Nervous System: Glial Cells
>3x more glial cells than neurons
astrocyte
maintain
ionic
environment
oligodendrocyte
myelinate
neurons
microglia
scavenge
cellular
debris
6. Overview of the Nervous System: CNS and PNS
Central Nervous System (CNS)
Cortex
Thalamus
Brainstem
Spinal cord
Peripheral Nervous System (PNS)
Cranial nerves
Spinal nerves
7. Overview of the Nervous System:: CNS and PNS
Brainstem:
midbrain
pons
medulla
cortex
thalamus
midbrain
pons
cervical
thoracic
lumbar
sacral
medulla
spinal cord
cerebellum
8. Overview of the Nervous System: Cortex and Thalamus
9. Overview of the Nervous System: Brainstem and Cranial Nerves
10. Overview of the Nervous System: Cranial Nerves
11. Overview of the Nervous System: Spinal Cord and Dermatomes
12. Finding Your Way About The Nervous System: Positional Terms
Rostr
al
Dorsa
l
Ventr
al
Caud
sal
Dor
al
tr
Ven
Caudal
al
13. Finding Your Way About The Nervous System: Positional Terms
Superior
Rostral
Ascending
Dorsal
Anterior
Ventral
Descending
Caudal
Inferior
Posterior
14. Finding Your Way About The Nervous System: Positional Terms
ipsilateral
contralateral
same side
opposite side
proximal
distal
close to point of reference
far from point of reference
efferent
afferent
projecting away from reference
projecting towards reference
midline
medial
lateral
decussate
line separating left and right
near midline
far from midline
cross midline
15. Finding Your Way About The Nervous System: Planes of Section
16. Finding Your Way About The Nervous System: Planes of Section
horizontal
horizontal
sagittal
coronal
coronal
sagittal
17. NEUROSCIENCE RULES
Neuroscience Rules!
• Symmetry
• Localization of Function
• Topography
• Contralaterality
• Cytoarchitecture
• Circuitry
18. NEUROSCIENCE RULES: Symmetry
Symmetry
Gray Matter
White Matter
Dorsal Horn
Ventral Horn
19. NEUROSCIENCE RULES: Symmetry
Symmetry
20. NEUROSCIENCE RULES: Localization of Function
Language
g
rin
a
e
H
Language
Vis
ion
Cognition
Tou
ch
Mo
vem
ent
Localization of function
21. NEUROSCIENCE RULES: Localization of Function
Localization of function
Human
Cat
Rat
22. Left Hemisphere Language areas
Localization of function
23. NEUROSCIENCE RULES: Topography
Topography
24. NEUROSCIENCE RULES: Topography
Topography
Homunculus
(somatotopic map)
25. Somatosensory and Motor Homunculi
Topography
Motor Homunculus
Somatosensory Homunculus
www.umsl.edu/~tsytsarev/tsytsarev_files/homunculus.jpg
26. NEUROSCIENCE RULES: Topography
Topography
Retinotopic map in
primary visual cortex
http://www.pc.rhul.ac.uk/courses/Lectures/PS1061/L2/frisby.jpg
27. NEUROSCIENCE RULES: Contralaterality
Somatosensory Cortex
decussation
primary afferent
Contralaterality
28. NEUROSCIENCE RULES: Contralaterality
Motor cortex
Contralaterality
axons of upper motor neurons
corticospinal tract
Midbrain
Pons
Medulla
decussation
Caudal Medulla
Spinal Cord
axons of lower motor neurons
29. NEUROSCIENCE RULES: Contralaterality
Contralaterality
decussation
Thalamus
Visual cortex
www.owlnet.rice.edu/~psyc351/Images/VisualPathways.jpg
30. NEUROSCIENCE RULES: Cytoarchitecture
Motor cortex has big
layer 5; small layer 4
Evolutionarily
older cortex has
fewer layers.
Cytoarchitecture
Sensory cortex has big
layer 4; small layer 5
31. NEUROSCIENCE RULES: Cytoarchitecture (Brodmann’s Areas)
Cytoarchitecture
3, 1, 2 = primary somatosensory cortex
4 = primary motor cortex
17 = primary visual cortex
41, 42 = primary auditory cortex
32. NEUROSCIENCE RULES: Cytoarchitecture
Cytoarchitecture
projection neuron
excitatory (glutamate)
70%
~2mm
interneuron
excitatory (glutamate)
or inhibitory (GABA)
30%
33. NEUROSCIENCE RULES: Circuitry (cortex)
Circuitry
34. NEUROSCIENCE RULES: Circuitry (spinal cord)
Circuitry
35. NEUROSCIENCE RULES
Neuroscience Rules!
• Symmetry
• Localization of Function
• Topography
• Contralaterality
• Cytoarchitecture
• Circuitry
36. CSF
Cerebrospinal Fluid (CSF)
Neurons are surrounded by an aqueous saline solution called
cerebrospinal fluid (CSF).
The CSF contains sodium (Na+), potassium (K+), chloride (Cl-),
calcium (Ca++), and other ions in solution.
The neuronal membrane itself (lipid bilayer) is impermable to the
movement of ions. However, ions can cross the membrane by two
means...
37. Transporters and Channels Move Ions Across the Neuronal Membrane
Ion Pump
Ion Channel
38. The Na+/K+ pump
39. Restiing Potential
The Resting Potential
The resting potential is negative because:
1. The K+ concentration is greater inside than outside the
neuron, due to the action of the sodium / potassium transporter
“pump.”
2. At rest, the neuron is primarily permeable to K+, because the
membrane contains K+ “leak” ion channels.
40. Diffusion and electrostatic (Coulomb) force
Two Physical Phenomena Establish the
Resting Potential
Diffusion: K+ diffuses out down its concentration gradient.
Electrostatic force: As K+ diffuses out, the inside becomes
negative compared to the outside. Eventually, K+ is
attracted strongly enough to the negative inside that the
diffusion stops. (Opposite charges attract).