Principles of CNS Organization (Week 1--Houser)

Question 1

Names for bundles of axons that are grouped together

Answer 1

Column

Fasciculus (bundle)

Lemniscus (ribbon)

Capsule (covering)

Peduncle (foot)

Question 2

Tract, or pathway

Answer 2

Group of axons with common origin, course and termination

Often cross to other side at some level of CNS

Named for origin and destination (spinothalamic, etc)

Question 3

Why is it that the right side of the cerebral cortex controls/senses the left side of the body?

Answer 3

Because major pathways between the cerebral cortex and spinal cord cross somewhere in the CNS

Question 4

Different ways to classify neurons

Answer 4

Destination of axon (projection/principal neurons and interneurons/local circuit neurons)

Shape (pyramidal, stellate, granule)

Pattern and location of axonal processes (chandalier?)

Chemical identity (NT)

Question 5

Lower motor neurons vs. upper motor neurons

Answer 5

Lower motor neurons: provide direct innervation of skeletal muscles; connect spinal cord to muscle; PNS

Upper motor neurons: part of descending system from cerebral cortex and brainstem centers; direct voluntary movements and activate motor programs for basic movements and postural control; connect brain and spinal cord; CNS

Question 6

What brain regions are involved in motor control?

Answer 6

Local spinal cord and brainstem circuits (lower motor neurons)

Local reflex circuits

Upper motor neurons

Cerebellum

Basal ganglia

Question 7

What kinds of fibers do peripheral nerves have?

Answer 7

Motor and sensory fibers in peripheral nerve

So, damage can lead to weakness and sensory loss

Question 8

Basal ganglia

Answer 8

Group of nuclei within cerebral hemisphere which are associated with motor control and motor planning

Composed of caudate, putamen, globus pallidus

Degeneration of basal ganglia leads to movement disorders in Parkinson’s and Huntington’s

Question 9

Brain stem

Answer 9

Medulla, pons, midbrain

Contains multiple pathways and cranial nerve nuclei III-XII

Question 10

Cerebellum

Answer 10

Cerebellar cortex, deep cerebellar nuclei, cerebellar peduncles (connections to brainstem)

Purkinje cells (with massive dendrites) here

Balance and coordination

Question 11

Thalamus

Answer 11

Part of diencephalon (along with hypothalamus)

Multiple nuclei that form two egg-shaped structures on each side of midline within cerebral hemispheres

Process specific type of incoming info and send it to cerebral cortex

Cerebral cortex sends info back to thalamus

Question 12

Hippocampus

Answer 12

Major region of limbic system

Located deep in temporal lobe

Learning, memory, consolidation of short-term to long-term memory

Prone to seizure activity (temporal lobe epilepsy), Alzheimer’s

Region of neuronal plasticity