Cerebral Hemispheres

1. Cerebral Cortex
2. Basal Ganglia

Diencephalon

1. Thalamus
2. Hypothalamus

Midbrain

Pons

Medulla

Prosencephalon

• Telencephalon (Cerebral Hemispheres)
• Diencephalon (Thalamus, Hypothalamus)

Mesencephalon (Midbrain)

Rhombencephalon

• Metencephalon (Pons, Cerebellum)
• Mylencephalon (Medulla)

1. What does Grey Matter contain?

2. What are some other terms for Grey Matter?

1. Cell Bodies, Dendrites, and Synapses

2. Cortex, Nuclei, Body, Center

1. What does White Matter contain?

2. What are some other names for White Matter?

1. Mylinated Tracts

2. Tract, Fasciculus, Peduncle, Funiculus, Leminscus

Anteriorly: Pons and Medulla

Posteriorly: Vermis of Cerebellum

10¹¹ - 10¹² neurons

10¹⁵ synaptic connections

1) Chemical and Electrical Synapses

2) Multiple Neurotransmitters and receptors

3) Complex cellular morphologies

4) Low safety factor at the level of individual synapses

Axosomatic synapses are ________.

Axodendritic synapses are ________.

Inhibitory

Excitatory

Permeable to Ca²⁺

Blocked by Mg²⁺

1. What is the inhibitory neurotransmitter in the brain?

2. What is the inhibitory neurotransmitter in the spinal cord?

1. GABA

2. Glycine

If Vrev > Vthreshold, then the synapse is _______.

If Vrev < Vthreshold, then the synapse is _______.

excitatory

inhibitory

1. Whether the input is inhibitory or excitatory.

2. Location of the synapse on the postsynaptic neuron

3. The size of the input

4. Proximity and relative strength of other synergistic and antagonistic snyapses.

1. Where are the cell bodies of afferent nerve fibers?

2. Where do they synapse?

1. Dorsal Root Ganglion

2. In the dorsal horn of the spinal cord

1. Increases the amplitude of the compound action potential

2. It recruits additional components to the waveform (smaller diameter axons which need higher stimulus intensities).

1. Must be synthesized in the presynaptic neuron.

2. Must be present in the presynaptic terminal and release in amount sufficient to exert an action on the postsynaptic neuron.

3. When applied exogenously, it mimics the action of the endogenously-released transmitter, activating the same ion channels or 2nd messenger systems.

4. A specific mechanism exists for removing it from its site of action

1. Neurotransmitter synthesis. This can occur in the cell body or at the axon terminal. The transmitter is stored in the synaptic vesicles.

2. Release of neurotransmitter into synaptic cleft. Ca2+ influx into the axon terminal causes the fusion of vesicle with presynaptic membrane and transmitter is released into the synaptic cleft.

3. Binding of neurotransmitter to receptor.

4. Inactivation of neurotransmitter

1. Attached to the cytoskeleton

2. In the releasable pool very close to the synaptic cleft.

1. Storage. Where vesicles are tethered to the cytoskeleton.

2. Trafficking and targeting of vesicles to active zones (Rab3A).

3. Docking of vesicles at active zones and their priming for release. 

4. Release of neurotransmitter.

1. Recognition of specific transmitters

2. Activation of effectors

1. Ionotropic receptors directly gate ion channels as part of a single macromolecule that also forms the ion channels.

2. Receptors that indirectly gate ion channels fall into two classes. 1) G protein coupled receptors 2) Receptor tyrosine kinases

1. cAMP cascade

2. inositol polyphosphate pathway

3. diacylglycerol

4. arachidonic acid

1. Modality

2. Duration

3. Location

4. Intensity

1. Touch

2. Proprioception

3. Nociception

4. Thermoception

Meissner's Corpuscle - Small - Rapid

Merkel Cells - Small - Slow

Pacinian Corpuscle - Large - Rapid

Ruffini Ending - Large - Slow

Vestibular

Muscle Spindles

Golgi Tendon Organ

Joint Receptors (Ruffini and Pacnian Corpuscles)

Stretch Receptors in Skin (Ruffini Endings, Merkel Discs)

Sense the length and speed of muscle contraction.

Increased activity in the 1a afferent informs that CNS that the muscle has been stretched.

Free Nerve Endings

Unmyelinated C fibers

Thinly myelinated Aδ fibers

1. Which fibers are responsible for the rapid component of pain?

2. Which fibers are responsible for the slow aching pain?

1. Aδ fibers

2. C fibers

Dorsal Horn

Intermediate Horn

Ventral Horn

1. Marginal Zone

2. Substantia Gelatinosa

3-6. Nucleus Proprius

7. Lateral Horn and Clarke's Nucleus

8. Interneurons

9. Motor Neurons

10. Propriospinal Zone

Phrenic Nucleus (C3-C5) - Controls Diaphragm

Clarke's Nucleus or Nucleu Dorsalis (T1-L3) - Relay nucleus for posterior spinocerebellar tract

Lateral Horn or Intermediolateral Cell Column (T1-L3) - Location of preganglionic sympathetic neurons

1. Dorsal Funiculi

2. Lateral Funiculi

3. Ventral Funiculi

1. What are the portions of the dorsal columns?

2. Which portion is only visible above T6?

1. Fasciculus Gracilis and Fasciculus Cuneatus

2. Fasciculus Cuneatus

1. Peripheral Receptor to DRG

2. Ascends in Fasciculus Gracilis or Cuneatus

3. Synapses in Nucleus Gracilis or Cuneatus in the medulla

4. Decussates via internal arcuate fibers in medulla

5. Enters into Medial Lemniscus pathway

6. Synapses in VPL of thalamus

7. Ascends through internal capsule

8. Synapses in Post-Central Gyrus

1. Peripheral Receptor

2. DRG sensory neuron

3. Through Lissauer's Tract

4. Synapses in substantia gelatinosa

5. Decussates in ventral white commisure

6. Ascends as spinothalamic tract

7. Synapses in VPL of thalamus

8. Ascends in internal capsule

9. Synapses in post central gyrus

1. Precentral Gyrus

2. Internal Capsule

3. Cerebral Peduncle

4. Pons

5. Pyramids of Medulla

6. Pyramidal Decussation

7. 85% in Lateral tract, 15% in anterior tract (later decussate in anterior commisure)

8. lower motor neurons in ventral horn

1. From Ipsilateral leg

2. Clark's nucleus

3. Posterior Spinal cerebellar tract

4. Cerebellum

1. Slow (red muscle)

2. Fast-fatigue resistable

3. Fast fatigable

Gamma Motor Axons

Group Ia and II afferent fibers

Muscle spindles detect changes in _____.

GTO detect changes in ______.

length

tension

Myasthenia Gravis

Alezheimer's Disease