Transcript Lecture 2b - Rio Hondo College

Lecture 2b
Anatomy of the Nervous System
Psych 210
Anatomy of the Nervous System
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Peripheral Nervous System
Central Nervous System
Peripheral Nervous System
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Somatic Nervous
System
Autonomic Nervous
System
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Sympathetic and
Parasympathetic
nervous systems
Key Concept
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Autonomic Nervous System
One system calms and the other arouses
 Does this setup make sense?
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Location terminology
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Superior vs. Inferior
 Dorsal vs Ventral
Anterior vs Posterior
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Rostral vs Caudal
Medial vs Lateral
Contralateral vs
Ipsilateral
Proximal vs Distal
Sagittal vs Coronal vs
Axial
Central Nervous System
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Spinal Cord
Brain
The Spinal Cord
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5 divisions of the spinal cord
8 cervical nerves
12 thoracic nerves
5 lumbar nerves
5 sacral nerves
1 coccygeal nerve (not
pictured)
Organization: Spinal Cord
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two major classes of
nerve fibers
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Grey matter
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motor descending fibers
(ventral portion)
sensory ascending fibers
(dorsal portion)
Cell bodies
White matter
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axons
Reflexes
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Without input from the brain
Patellar reflex
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Knee jerk reaction
Withdrawal reflex
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Removal of hand from hot or sharp surfaces
Damage to the Spinal Cord
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If damaged, patients
have loss of sensation
and movement to areas
served by the damaged
nerves and to areas
below the damage
The Brain
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Two main
classifications:
 Brainstem
 Cerebrum
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Parts of the Brainstem: The
Primarily white matterMedulla
(axons)
Majority of information
going to and from higher
structures pass through the
medulla
Contains various groups of
cell bodies (nuclei)
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Reticular formation
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Responsible for breathing,
heart rate, blood pressure
Responsible for sleep and
arousal
Damage to the medulla is
fatal
Parts of the Brainstem: The Pons
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Connects the medulla to
higher brain structures
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Pons means “bridge” in latin
Mostly white matter (axons)
Connections to the ear
Processes sleep and arousal
Parts of the Brainstem: The
Cerebellum
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“little brain”
Coordination
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Balance
Damage here effects skilled
movements
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Puts together sequences of
movements
Also may effect speech
One of the first brain
structures affected by alcohol
Across Species: the cerebellum
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Size of cerebellum and the meaning of its size has been
up for debate
Across mammals, the relative size of the cerebellum
when compared to the brain is fairly constant
Whales, dolphins, and bats seem to have a larger
cerebellum: brain ratio
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Possibly due to the fact that these animals have SONAR
capabilities
All speculation at this point
Parts of the Brainstem: The
Tectum
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Consists of four bump-like structures
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Superior colliculus
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inferior colliculus and superior colliculus
One step in the pathway from the optic nerve to the
visual areas of the brain
Inferior colliculus
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One step in the pathway from the auditory nerve to
the auditory areas of the brain
Parts of the Brainstem: The
Diencephalon
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two structures
the hypothalamus
 the thalamus
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The Hypothalamus
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Eating, drinking, sex,
circadian rhythms,
temperature control
Emotional behavior
Fight or flight responses
Termed a “pleasure
center”
The Pleasure center
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1956: Electrodes were placed in the rat’s hypothalamus
Rats were taught to press a bar to turn on the electrode
and stimulate their hypothalamus
In experiments, rats would do nothing but push the
bar
Up to 5000 times
Only stopped when they dropped from exhaustion
Food deprived rats given the choice of food or
stimulation: chose stimulation
The Thalamus
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pair of structures (one in each
half)
incoming sensory information
relays in the thalamus before
entering the cerebral cortex.
many sensory, motor, and
cognitive functions
highly organized connections
with cortex
connections are mostly
reciprocal
The Cerebrum
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Main seat of
Cognition
Subcortex
Cortex
The cortex
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Six lobes
Two hemispheres
Subhemispheric
structures
The Lobes
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Four main lobes
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Frontal: motor and higher
order functions
Parietal: somatosensory
Temporal: audition
Occipital: vision
Two other lobes
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Limbic
Insular
Landmarks
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Gyrus – bumps in brain
Sulcus- depressions in
the brain
Gyrus
Sulcus
Main Landmarks
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Central Sulcus
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Lateral Sulcus (aka Sylvian
Fissure)
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Separates frontal and parietal
lobes from the temporal lobe
Longitudinal Fissure
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Separates frontal lobe from
parietal lobe
Separates the two hemispheres
Fissure: Large sulcus
Types of Cortex
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Two main types
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Primary
Receives direct input from sensory areas
 Only receives information from one type of sense
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Non-primary
Receives information from other cortical areas
 Can be from only one sense (unimodal)
 Can be from multiple senses (multimodal)
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Primary sensory areas
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Primary visual:
calcarine sulcus
Primary auditory:
Heschl's gyrus
Primary
somatosensory:
post-central gyrus
Primary motor: precentral gyrus
Post-central
Pre-central gyrus
gyrus
Heschl’s gyrus (not
visible)
Primary Visual Cortex
Calcarine sulcus
The Limbic Lobe
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Primarily
responsible for
emotional aspects
of life
In the center of the
brain
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Hippocampus
Amygdala
Cingulate gyrus
Fornix
Laminar organization
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cortex itself has a thickness of only about 3-4mm.
VERY well organized
6 layers, or laminae, (Neocortex)
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Layer IV is the primary (but not exclusive) input layer
Layers II and III are cortico-cortical output layers,
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Layers V and VI descending output layers
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II= ipsi
III= contra
V = basal ganglia/thal/brain stem/spinal cord
VI = thal/claustrum
Cytoarchitecture
Laminar Organization
Brodmann
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Tried to map out
different areas of the
brain based upon
laminar organization
Semi accurate
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area 17 is primary
visual cortex
Principles of Connectivity
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cortical connections are selective
a majority, but not all, of the connections are
reciprocal
hierarchical and parallel organization
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Hierarchical
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processing proceeds in stages with each stage building on
the computations carried out in the earlier stage
Parallel
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Processing occurs in two ways at the same time
(separately)