Central Nervous System Notes | EduRev

: Central Nervous System Notes | EduRev

 Page 1


1
Central Nervous 
System
Lecture Outline
• Spinal Cord Design & Function
• Functional Brain Regions
– Flow of Information
– Learning
Central Nervous System
Spinal Cord Design & Function
• Design = Function
– Gray matter =
• integration of information 
– White matter tracts = 
• flow of information
Central Nervous System
Spinal Cord Design & Function
Efferent Tracts (red)
1.Pyramidal Tracts
1a.  Lateral corticospinal tract
1b.  Anterior corticospinal tract
2.Extrapyramidal Tracts
2a.  Rubrospinal tract
2b.  Reticulospinal tract
2c.  Vestibulospinal tract
2d.  Olivospinal tract
Afferent Tracts (blue)
3. Posterior Column-Medial Lemniscus tract
3a. Fasciculus gracilus
3b.  Fasciculus cuneatus
4.  Spinocerebellar Tract
4a.  Posterior spinocerebellar tract
4b.  Anterior spinocerebellar tract
5. Anterolateral System
5a.  Lateral Spinothalamic tract
5b.  Anterior Spinothalamic tract
6.  Spino-olivary tract
S = sacral, L = lumbar, 
Th = thoracic, C = cervical
Page 2


1
Central Nervous 
System
Lecture Outline
• Spinal Cord Design & Function
• Functional Brain Regions
– Flow of Information
– Learning
Central Nervous System
Spinal Cord Design & Function
• Design = Function
– Gray matter =
• integration of information 
– White matter tracts = 
• flow of information
Central Nervous System
Spinal Cord Design & Function
Efferent Tracts (red)
1.Pyramidal Tracts
1a.  Lateral corticospinal tract
1b.  Anterior corticospinal tract
2.Extrapyramidal Tracts
2a.  Rubrospinal tract
2b.  Reticulospinal tract
2c.  Vestibulospinal tract
2d.  Olivospinal tract
Afferent Tracts (blue)
3. Posterior Column-Medial Lemniscus tract
3a. Fasciculus gracilus
3b.  Fasciculus cuneatus
4.  Spinocerebellar Tract
4a.  Posterior spinocerebellar tract
4b.  Anterior spinocerebellar tract
5. Anterolateral System
5a.  Lateral Spinothalamic tract
5b.  Anterior Spinothalamic tract
6.  Spino-olivary tract
S = sacral, L = lumbar, 
Th = thoracic, C = cervical
2
– The Somatosensory Pathways
• Posterior Column-Medial 
Lemniscus tract (PCML)
– Ascends in the posterior columns
– Crosses over in the medial 
lemniscus of the medulla 
oblongata
– Used for
» Discriminative touch
»Vibration
» Conscious proprioception
Central Nervous System
Spinal Cord Design & Function
Central Nervous System
Spinal Cord Design & Function
• The Somatosensory Pathways
– Spinothalamic tracts
• crosses over at level of 
entrance into spinal cord
• Used for
– simple (crude) touch - anterior
– pain (most)
– temperature
lateral
• The Proprioceptive 
Pathways (non-conscious)
– Spinocerebellar tracts
• Relay information from golgi 
organs and muscle spindles
• Posterior (dorsal) tract is 
ipsilateral to cerebellum via 
cerebellar peduncles
• Anterior (ventral) tract contains 
crossed and ipsilateral fibers for 
lower limbs
• Some proprioceptive signals are 
carried in the fasciculus 
cuneatus pathway – upper limbs
Central Nervous System
Spinal Cord Design & Function
• Spino-Olivary Tracts
– Contains type Ib afferent sensory fibers
• Originate from golgi tendon organs
• Synapse in the olivary nucleus of medulla
•2
nd
order neurons project to the cerebellum
Central Nervous System
Spinal Cord Design & Function
Page 3


1
Central Nervous 
System
Lecture Outline
• Spinal Cord Design & Function
• Functional Brain Regions
– Flow of Information
– Learning
Central Nervous System
Spinal Cord Design & Function
• Design = Function
– Gray matter =
• integration of information 
– White matter tracts = 
• flow of information
Central Nervous System
Spinal Cord Design & Function
Efferent Tracts (red)
1.Pyramidal Tracts
1a.  Lateral corticospinal tract
1b.  Anterior corticospinal tract
2.Extrapyramidal Tracts
2a.  Rubrospinal tract
2b.  Reticulospinal tract
2c.  Vestibulospinal tract
2d.  Olivospinal tract
Afferent Tracts (blue)
3. Posterior Column-Medial Lemniscus tract
3a. Fasciculus gracilus
3b.  Fasciculus cuneatus
4.  Spinocerebellar Tract
4a.  Posterior spinocerebellar tract
4b.  Anterior spinocerebellar tract
5. Anterolateral System
5a.  Lateral Spinothalamic tract
5b.  Anterior Spinothalamic tract
6.  Spino-olivary tract
S = sacral, L = lumbar, 
Th = thoracic, C = cervical
2
– The Somatosensory Pathways
• Posterior Column-Medial 
Lemniscus tract (PCML)
– Ascends in the posterior columns
– Crosses over in the medial 
lemniscus of the medulla 
oblongata
– Used for
» Discriminative touch
»Vibration
» Conscious proprioception
Central Nervous System
Spinal Cord Design & Function
Central Nervous System
Spinal Cord Design & Function
• The Somatosensory Pathways
– Spinothalamic tracts
• crosses over at level of 
entrance into spinal cord
• Used for
– simple (crude) touch - anterior
– pain (most)
– temperature
lateral
• The Proprioceptive 
Pathways (non-conscious)
– Spinocerebellar tracts
• Relay information from golgi 
organs and muscle spindles
• Posterior (dorsal) tract is 
ipsilateral to cerebellum via 
cerebellar peduncles
• Anterior (ventral) tract contains 
crossed and ipsilateral fibers for 
lower limbs
• Some proprioceptive signals are 
carried in the fasciculus 
cuneatus pathway – upper limbs
Central Nervous System
Spinal Cord Design & Function
• Spino-Olivary Tracts
– Contains type Ib afferent sensory fibers
• Originate from golgi tendon organs
• Synapse in the olivary nucleus of medulla
•2
nd
order neurons project to the cerebellum
Central Nervous System
Spinal Cord Design & Function
3
• The Motor Pathways
– The Pyramidal Tracts
• Anterior (Ventral) 
Corticospinal Tract
• Lateral Corticospinal 
Tract
Central Nervous System
Spinal Cord Design & Function
• The Motor Pathways
– Extrapyramidal Tracts
• Play a role in coordination of movement and posture
• All receive input from cerebellum
– Rubrospinal tract
» gross limb movement
» Not well formed in humans
– Reticulospinal tract
» coordinates movements of locomotion and posture
» Influences muscle tone
» Descends from the RAS
– Tectospinal tract
» Coordinates head and eye movements in response to 
visual and auditory stimuli
– Vestibulospinal tract
» control of muscles for equilibrium including movement of 
head/neck
Central Nervous System
Spinal Cord Design & Function
• The brain is designed with 
two systems
–Wired System
• Neurons & 
Associated 
Neural Circuits 
and Pathways
– Diffuse Modulatory Systems
• Uses neurohormones to modulate function of the 
“wired system”
– Dopamine, Serotonin, Norepinephrine, Acetylcholine
Central Nervous System
Brain Design & Function
• Diffuse Modulatory Systems
– Norepinephrine
Central Nervous System
Brain Design & Function
• Locus coeruleus is the origin of 
cell bodies that secrete 
norepinephrine to most of the 
CNS.
• Activated strongly when new 
sensory stimuli are encountered
• Regulate vigiliance & 
attentiveness, inactive during 
sleep
• Overactivity = axiety
• Underactivity = depression
Page 4


1
Central Nervous 
System
Lecture Outline
• Spinal Cord Design & Function
• Functional Brain Regions
– Flow of Information
– Learning
Central Nervous System
Spinal Cord Design & Function
• Design = Function
– Gray matter =
• integration of information 
– White matter tracts = 
• flow of information
Central Nervous System
Spinal Cord Design & Function
Efferent Tracts (red)
1.Pyramidal Tracts
1a.  Lateral corticospinal tract
1b.  Anterior corticospinal tract
2.Extrapyramidal Tracts
2a.  Rubrospinal tract
2b.  Reticulospinal tract
2c.  Vestibulospinal tract
2d.  Olivospinal tract
Afferent Tracts (blue)
3. Posterior Column-Medial Lemniscus tract
3a. Fasciculus gracilus
3b.  Fasciculus cuneatus
4.  Spinocerebellar Tract
4a.  Posterior spinocerebellar tract
4b.  Anterior spinocerebellar tract
5. Anterolateral System
5a.  Lateral Spinothalamic tract
5b.  Anterior Spinothalamic tract
6.  Spino-olivary tract
S = sacral, L = lumbar, 
Th = thoracic, C = cervical
2
– The Somatosensory Pathways
• Posterior Column-Medial 
Lemniscus tract (PCML)
– Ascends in the posterior columns
– Crosses over in the medial 
lemniscus of the medulla 
oblongata
– Used for
» Discriminative touch
»Vibration
» Conscious proprioception
Central Nervous System
Spinal Cord Design & Function
Central Nervous System
Spinal Cord Design & Function
• The Somatosensory Pathways
– Spinothalamic tracts
• crosses over at level of 
entrance into spinal cord
• Used for
– simple (crude) touch - anterior
– pain (most)
– temperature
lateral
• The Proprioceptive 
Pathways (non-conscious)
– Spinocerebellar tracts
• Relay information from golgi 
organs and muscle spindles
• Posterior (dorsal) tract is 
ipsilateral to cerebellum via 
cerebellar peduncles
• Anterior (ventral) tract contains 
crossed and ipsilateral fibers for 
lower limbs
• Some proprioceptive signals are 
carried in the fasciculus 
cuneatus pathway – upper limbs
Central Nervous System
Spinal Cord Design & Function
• Spino-Olivary Tracts
– Contains type Ib afferent sensory fibers
• Originate from golgi tendon organs
• Synapse in the olivary nucleus of medulla
•2
nd
order neurons project to the cerebellum
Central Nervous System
Spinal Cord Design & Function
3
• The Motor Pathways
– The Pyramidal Tracts
• Anterior (Ventral) 
Corticospinal Tract
• Lateral Corticospinal 
Tract
Central Nervous System
Spinal Cord Design & Function
• The Motor Pathways
– Extrapyramidal Tracts
• Play a role in coordination of movement and posture
• All receive input from cerebellum
– Rubrospinal tract
» gross limb movement
» Not well formed in humans
– Reticulospinal tract
» coordinates movements of locomotion and posture
» Influences muscle tone
» Descends from the RAS
– Tectospinal tract
» Coordinates head and eye movements in response to 
visual and auditory stimuli
– Vestibulospinal tract
» control of muscles for equilibrium including movement of 
head/neck
Central Nervous System
Spinal Cord Design & Function
• The brain is designed with 
two systems
–Wired System
• Neurons & 
Associated 
Neural Circuits 
and Pathways
– Diffuse Modulatory Systems
• Uses neurohormones to modulate function of the 
“wired system”
– Dopamine, Serotonin, Norepinephrine, Acetylcholine
Central Nervous System
Brain Design & Function
• Diffuse Modulatory Systems
– Norepinephrine
Central Nervous System
Brain Design & Function
• Locus coeruleus is the origin of 
cell bodies that secrete 
norepinephrine to most of the 
CNS.
• Activated strongly when new 
sensory stimuli are encountered
• Regulate vigiliance & 
attentiveness, inactive during 
sleep
• Overactivity = axiety
• Underactivity = depression
4
• Diffuse Modulatory Systems
– Serotonin
Central Nervous System
Brain Design & Function
• Serotonin released by neurons of 
the raphe nuclei in the brain stem
• Rostral nuclei project to the 
thalamus and cerebrum
• Mediate sleep/wake cycles
• Alter mood
• Caudal nuclei project to the 
cerebellum and spinal cord
• Modulate pain and 
locomotion
To basal 
nuclei
• Diffuse Modulatory Systems
– Dopamine
Central Nervous System
Brain Design & Function
• Dopamine released by the substantia
nigra and the ventral tegmental area 
of the brain stem (midbrain)
• Substantia nigra neurons project to 
the basal ganglia (caudate nuclei and 
putamen)
• Mediate movement
• Loss = parkinsons
• Ventral tegmental area neurons 
project to the prefrontal cortex & limbic 
system
• Reinforces behaviors associated 
with pleasure
Prefrontal 
cortex
• Diffuse Modulatory Systems
– Acetylcholine
Central Nervous System
Brain Design & Function
• Ach secreting neurons have cell 
bodies located in the ventral 
telencephalon and the pons
• Project to the cerebrum, 
hippocampus and thalamus
• Linked to
• learning and memory
• Sleep wake cycles
• Arousal & sensory information
• Alzheimer’s disease may be 
linked to the deterioration of this 
system
Cingulate 
gyrus
Central Nervous System
Brain Design & Function
Page 5


1
Central Nervous 
System
Lecture Outline
• Spinal Cord Design & Function
• Functional Brain Regions
– Flow of Information
– Learning
Central Nervous System
Spinal Cord Design & Function
• Design = Function
– Gray matter =
• integration of information 
– White matter tracts = 
• flow of information
Central Nervous System
Spinal Cord Design & Function
Efferent Tracts (red)
1.Pyramidal Tracts
1a.  Lateral corticospinal tract
1b.  Anterior corticospinal tract
2.Extrapyramidal Tracts
2a.  Rubrospinal tract
2b.  Reticulospinal tract
2c.  Vestibulospinal tract
2d.  Olivospinal tract
Afferent Tracts (blue)
3. Posterior Column-Medial Lemniscus tract
3a. Fasciculus gracilus
3b.  Fasciculus cuneatus
4.  Spinocerebellar Tract
4a.  Posterior spinocerebellar tract
4b.  Anterior spinocerebellar tract
5. Anterolateral System
5a.  Lateral Spinothalamic tract
5b.  Anterior Spinothalamic tract
6.  Spino-olivary tract
S = sacral, L = lumbar, 
Th = thoracic, C = cervical
2
– The Somatosensory Pathways
• Posterior Column-Medial 
Lemniscus tract (PCML)
– Ascends in the posterior columns
– Crosses over in the medial 
lemniscus of the medulla 
oblongata
– Used for
» Discriminative touch
»Vibration
» Conscious proprioception
Central Nervous System
Spinal Cord Design & Function
Central Nervous System
Spinal Cord Design & Function
• The Somatosensory Pathways
– Spinothalamic tracts
• crosses over at level of 
entrance into spinal cord
• Used for
– simple (crude) touch - anterior
– pain (most)
– temperature
lateral
• The Proprioceptive 
Pathways (non-conscious)
– Spinocerebellar tracts
• Relay information from golgi 
organs and muscle spindles
• Posterior (dorsal) tract is 
ipsilateral to cerebellum via 
cerebellar peduncles
• Anterior (ventral) tract contains 
crossed and ipsilateral fibers for 
lower limbs
• Some proprioceptive signals are 
carried in the fasciculus 
cuneatus pathway – upper limbs
Central Nervous System
Spinal Cord Design & Function
• Spino-Olivary Tracts
– Contains type Ib afferent sensory fibers
• Originate from golgi tendon organs
• Synapse in the olivary nucleus of medulla
•2
nd
order neurons project to the cerebellum
Central Nervous System
Spinal Cord Design & Function
3
• The Motor Pathways
– The Pyramidal Tracts
• Anterior (Ventral) 
Corticospinal Tract
• Lateral Corticospinal 
Tract
Central Nervous System
Spinal Cord Design & Function
• The Motor Pathways
– Extrapyramidal Tracts
• Play a role in coordination of movement and posture
• All receive input from cerebellum
– Rubrospinal tract
» gross limb movement
» Not well formed in humans
– Reticulospinal tract
» coordinates movements of locomotion and posture
» Influences muscle tone
» Descends from the RAS
– Tectospinal tract
» Coordinates head and eye movements in response to 
visual and auditory stimuli
– Vestibulospinal tract
» control of muscles for equilibrium including movement of 
head/neck
Central Nervous System
Spinal Cord Design & Function
• The brain is designed with 
two systems
–Wired System
• Neurons & 
Associated 
Neural Circuits 
and Pathways
– Diffuse Modulatory Systems
• Uses neurohormones to modulate function of the 
“wired system”
– Dopamine, Serotonin, Norepinephrine, Acetylcholine
Central Nervous System
Brain Design & Function
• Diffuse Modulatory Systems
– Norepinephrine
Central Nervous System
Brain Design & Function
• Locus coeruleus is the origin of 
cell bodies that secrete 
norepinephrine to most of the 
CNS.
• Activated strongly when new 
sensory stimuli are encountered
• Regulate vigiliance & 
attentiveness, inactive during 
sleep
• Overactivity = axiety
• Underactivity = depression
4
• Diffuse Modulatory Systems
– Serotonin
Central Nervous System
Brain Design & Function
• Serotonin released by neurons of 
the raphe nuclei in the brain stem
• Rostral nuclei project to the 
thalamus and cerebrum
• Mediate sleep/wake cycles
• Alter mood
• Caudal nuclei project to the 
cerebellum and spinal cord
• Modulate pain and 
locomotion
To basal 
nuclei
• Diffuse Modulatory Systems
– Dopamine
Central Nervous System
Brain Design & Function
• Dopamine released by the substantia
nigra and the ventral tegmental area 
of the brain stem (midbrain)
• Substantia nigra neurons project to 
the basal ganglia (caudate nuclei and 
putamen)
• Mediate movement
• Loss = parkinsons
• Ventral tegmental area neurons 
project to the prefrontal cortex & limbic 
system
• Reinforces behaviors associated 
with pleasure
Prefrontal 
cortex
• Diffuse Modulatory Systems
– Acetylcholine
Central Nervous System
Brain Design & Function
• Ach secreting neurons have cell 
bodies located in the ventral 
telencephalon and the pons
• Project to the cerebrum, 
hippocampus and thalamus
• Linked to
• learning and memory
• Sleep wake cycles
• Arousal & sensory information
• Alzheimer’s disease may be 
linked to the deterioration of this 
system
Cingulate 
gyrus
Central Nervous System
Brain Design & Function
5
Central Nervous System
Brain Design & Function
• So… how does the brain “do” things?
– Create voluntary movements
– Forming Memories
– Communication:  thought ? expression
– Idea of “self” or consciousness
– Create emotions
– Experience pain & pleasure
– Go to sleep & wake up
Central Nervous System
Brain Design & Function
• Voluntary Movement
– The players: Cerebral Cortex, Basal 
Ganglia & Cerebellum
• Cerebral cortex
– Contains the primary motor cortex, 
supplemental motor areas, pre-
motor areas and the prefrontal 
cortex
» The primary motor cortex 
contains your “motor 
homunculus”
– Also has cortices for all of your 
other senses which may play a role 
in your voluntary movement
» posterior parietal cortex 
“asesses” current status with 
regard to body position and 
target
Central Nervous System
Brain Design & Function
• Voluntary Movement
• Basal Ganglia
– Play an indirect 
role in movement 
by forming a 
processing loop 
between the basal 
ganglia, the cortex 
and thalamus
Central Nervous System
Brain Design & Function
• Voluntary Movement
• Cerebellum
– Cerebellum is the 
center for 
proprioception and 
continually modifies 
output to meet the 
goal of the movement
– Also stores learned 
motor skills
– Connected to both 
cortex and 
brainstem/spinal cord
Read More
Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!