the cerebrum/ telencephalon

Question 1

what is the telencephalon

Answer 1

• most rostral, highly differentiated and functionally complex portion of the CNS
• lesions generally create contralateral sensory and motor signs - can include blindness, depression, seizures
• involved in higher functions: perception, learning, short and long term voluntary control of movement, sensory discrimination, thinking and planning

Question 2

cerebral cortex

Answer 2

consists of lobes - frontal, parietal, temporal, occipital, and primiform

Question 3

white matter

Answer 3

region of underlying white matter consisting of corona radiata that carry axons from individual gyri into and out of the internal capsules, which is the major fiber bundle attaching the telencephalon to the brainstem

Question 4

commisures

Answer 4

• white matter commisures that connect the two cerebral hemispheres
• biggest is the corpus calosum
• commisures of the fornix (hippocampal commisure)
• rostral (anterior) connecting the two temporal lobes of the cerebral hemispheres across the midline
• caudal (posterior) commisures interconnects the pretectal nuclei, mediating the consensual pupillary light reflex

Question 5

ventricles

Answer 5

lateral ventricles of the ventricular system

Question 6

basal ganglia

Answer 6

participate in complex locomotor behavior and emotions

Question 7

basal forebrain

Answer 7

important in memory

Question 8

neocortex: frontal, parietal, occipital, and temporal lobes

Answer 8

• most modern, largest and most developed part of the cortex
• only in mammals, 6 layers

Question 9

archiocortex: hippocampus

Answer 9

• involved in declarative memory function
• spatial memory, cognitive map of space
• mood, reward

Question 10

paleocortex: olfactory cortex or piriform lobe

Answer 10

separated from neocortex by the rhinal fissure

Question 11

what do each of the 6 layers of the neocortex do

Answer 11

• layer 4 - input layer
• local circuits - local connectivity between layers
• layer 2 and 3 - to other cortical areas: local circuit, short association, long association
• layer 5 - to subcortical areas (spinal cord, brainstem, basal ganglia)
• layer 6 - feedback to thalamus

Question 12

what is brodmann’s 52 cytoarchitectonic regions of neocortex

Answer 12

differences in

• cell shapes
• cell sizes
• packing densities

Question 13

somatosensory primary receiving areas (SI and SII) in neocortex - all topographically organized:

Answer 13

• mapping sensory sheet (retina, skin, etc) onto primary receiving areas (for sensory systems)
• somatotopic motor map in M1 matches map in S1

Question 14

origin of the corticospinal tract (UMN)

Answer 14

• initiation of complex voluntary movemenbt
• activity in M1 neurons occurs before and during a voluntary movement
• activity encodes force and direction of movement

Question 15

effect of corticospinal tract lesions

Answer 15

• difficulty moving distal limbs
• loss of ability to make independent finger movements - does not recover

Question 16

what is area 6 - supplementary motor area, SMA - premotor area, PMA involved in?

Answer 16

motor planning

Question 17

lateral pathways

Answer 17

• voluntary movement of distal musculature
• unde direct cortical control
• innervate distal musculature

Question 18

ventromedial pathways

Answer 18

• control of posture, locomotion, orienting and balance
• under brainstem control
• innervate axial and proximal musculature

Question 19

what are the two tracts of the lateral spinal pathways

Answer 19

• corticospinal tract: limbs
• rubrospinal tract: distal limb muscles

Question 20

corticobulbar tract

Answer 20

• travels with CST and provides UMN innervation to LMNs in cranial nerve motor nuclei
• face, jaw, tongue, and throat

Question 21

corticopontine

Answer 21

to pontine nuclei

Question 22

balance tract

Answer 22

vestibulospinal tract

Question 23

orienting reflexes

Answer 23

• tectospinal tract: head
• tecobulbar: eyes

Question 24

what tracts are for posture and locomotion

Answer 24

• pontine reticulospinal tract
• medullary reticulospinal tract

Question 25

what are clinical signs of UMN lesions

Answer 25

• increased tone (spasticity)
• hyperactive reflexes
• pathological reflexes

Question 26

what are the clinical signs of LMN lesions

Answer 26

• decreased tone
• hypactive reflexes
• weakness
• atrophy
• fasciculations

Question 27

what do the basal ganglia and cerebellum act on

Answer 27

cerebral cortex through relay nuclei in the thalamus

Question 28

what are the 3 sections of the basal ganglia

Answer 28

• caudate
• globus pallidus
• putamen

Question 29

striatum is ____ station for basal ganglia
globus pallidus is ____ of basal ganglia

Answer 29

input; output

Question 30

globus pallidus tonically ____ VL thalamus

Answer 30

inhibits

Question 31

anything that increases GP output leads to:

Answer 31

hypokinesis (parkinson’s) degeneration of dopaminergic cells in substantia nigra

Question 32

decreased GP output leads to:

Answer 32

hyperkinesis (hemiballisum) - loss of tonic inhibitory output to thalamus, cell loss in subthalamus

Question 33

basal ganglia damage produces two basic disturbances related to motor activity in humans:

Answer 33

1. disturbances of muscle tone (hypotonia or hypertonia)
2. dyskinesias (abnormal involuntary movements)

• athetosis
• chorea
• ballismus
• resting tremor

Question 34

in animals with basal ganglia lesions the most typical disturbance of motor activity is one of excessive locomotion - constant pacing or ____

Answer 34

hyperkinesia