Transcript Document

Chapter 4
Anatomy of the Nervous
System
chapter 4
Frontal lobe damage
Phineas Gage, 1848
chapter 4
Frontal lobe damage
Travis Bogumill, 1998
Jarod Behee, 2007
Wilder Penfield: Mapping the Cortex, 1947
Modern techniques for studying the brain
• Lesion
– damage to a brain area
(electrical or chemical)
• Ablation
– removal of brain area
• Stereotaxic instrument
– a device that allows for precise
neurosurgical procedures
• Sham lesion
– performing identical
procedures except for
damaging the brain
– produced by an experimenter
in a control subject
Modern techniques for studying the brain
• Positron-emission tomography (PET Scan)
– records emission of radioactivity from injected
radioactive chemicals to produce a highresolution image
– shows where activity occurs in the brain
Modern techniques for studying the brain
Recording brain activity
involves using a variety of
noninvasive methods
including:
• Magnetic Resonance
Imaging (MRI)
– involves the application
of a powerful magnetic
field to image the brain
– good for viewing soft
tissue
Modern techniques for studying the brain
• Electroencephalography
(EEG)
– Records electrical activity
produced by cortical regions
of the brain
– Produces a record of
brainwaves.
– Widely used for sleep
research
Structure of the Vertebrate Nervous
System
• Neuroanatomy is the anatomy of the nervous
system.
• Refers to the study of the various parts of the
nervous system and their respective
function(s).
• The nervous system consists of many
substructures, each comprised of many
neurons.
Structure of the Vertebrate Nervous
System
•
The Nervous System
is comprised of two
major subsystems:
1. The Central
Nervous System
(CNS)—brain and
spinal cord
2. The Peripheral
Nervous System
(PNS)
Central Nervous System
 Brain
 Comprised of 100 billion
neurons
 “Command Central” of
the nervous system
 Spinal cord
 the part of the CNS
found within the spinal
column
 communicates with the
sense organs and
muscles below the level
of the head
 Functions according to
the Bell-Magendie law
Central Nervous System
 The Bell-Magendie law states the entering dorsal roots carry
sensory information and the exiting ventral roots carry motor
information.
Fig. 4-3, p. 84
Peripheral Nervous System
•
The Peripheral
Nervous
System (PNS)
sends
information to
the CNS and
is comprised
of the:
1. Somatic
Nervous
System
2. Autonomic
Nervous
System
Peripheral Nervous System
• The Somatic
Nervous System
consists of nerves
that:
– Convey sensory
information to
the CNS.
– Transmit
messages for
motor
movement from
the CNS to the
body.
– Control skeletal
muscles
Peripheral Nervous System
•
The autonomic
nervous system
regulates the
automatic behaviors
of the body (heart
rate, blood pressure,
respiration, digestion
etc).
•
Divides into 2
subsystems:
1. The Sympathetic
Nervous System
2. The Parasympathetic
Nervous System
Peripheral Nervous System
• Sympathetic nervous
system: a network of
nerves that prepares
the organs for
rigorous activity by
increasing:
– heart rate
– blood pressure
– respiration
– etc.
• Responsible for “fight
or flight” response
Peripheral Nervous System
• The parasympathetic
nervous system
facilitates vegetative,
nonemergency
responses by the
organs.
– decreases functions
increased by the
sympathetic nervous
system.
– dominant during our
relaxed states.
Anatomical Terms:
Views
Terms used to describe
views when referring to
the nervous system
include:
Ventral: toward the stomach
Dorsal: toward the back
Ventral
Dorsal
Anatomical Terms:
Views
Terms used to describe views
when referring to the
nervous system include:
Anterior: toward the front end
Posterior: toward the back end
Lateral: toward the side
anterior
posterior
lateral
Anatomical Terms:
Location/direction
Terms used to describe
location/direction in the
nervous system include:
Superior: above another part
Inferior: below another part
Anatomical Terms:
Location/Direction
Terms used to describe
location/direction in the
nervous system include:
Lateral: toward the side
Medial: toward the midline
Anatomical Terms:
Location/Direction
Terms used to describe
location/direction in the
nervous system include:
Ipsilateral: on same side
Contralateral: on opposite side
Anatomical Terms:
Planes/Sections/Cuts
Terms referring to
planes/sections/cuts:
Horizontal: shows brain
structures as seen from
the top
Sagittal: shows brain
structures as seen from
the side
Coronal: shows brain
structures as seen from
the front
Table 4-1, p. 83
Anatomical Terms:
Specialized Parts
Terms referring to
specialized parts of the
nervous system:
Gray matter: cell bodies
and dendrites
White matter: axons,
mostly myelinated
Table 4-1, p. 83
Anatomical Terms:
Specialized Parts
Terms referring to
specialized parts of the
nervous system:
Tract/projection: set of
axons in the CNS
Nerve: set of axons in the
PNS
Nucleus: cluster of
neuron cell bodies
within CNS
Ganglion: cluster of
neuron cell bodies in
the PNS
Table 4-1, p. 83
Anatomical Terms:
Specialized Parts
Terms referring to
specialized parts of the
nervous system:
Gyrus (pl: gyri): mound on
surface of brain
Sulcus (pl: sulci):
fold/groove separating
one gyrus from another
Fissure: long, deep sulcus
Table 4-1, p. 83
Neuroanatomy Handout #3: Brain Structures
•
The brain can be divided into three major
divisions:
1. Hindbrain.
2. Midbrain.
3. Forebrain.
Neuroanatomy Handout #3: Brain Structures
• The Hindbrain
consists of the:
– Medulla
– Pons
– Cerebellum
• Located at the
posterior portion of
the brain
Neuroanatomy Handout #3: Brain Structures
• The medulla (A):
– Located just above the
spinal cord
– Responsible for vital
reflexes such as
breathing, heart rate,
vomiting, salivation,
coughing and
sneezing.
• Cranial nerves allow the
medulla to control
sensations from the head,
muscle movements in the
head, and many
parasympathetic outputs
to the organs.
Table 4-4, p. 88
Neuroanatomy Handout #3: Brain Structures
• Pons (B)
– lies on each side of
the medulla (ventral
and anterior).
– along with the
medulla, contains the
reticular formation and
raphe system, which
work together to
increase arousal and
readiness of other
parts of the brain
Neuroanatomy Handout #3: Brain Structures
• Cerebellum (C):
– located posterior to the
brainstem with many
deep folds
– helps regulate motor
movement, balance and
coordination
– also important for
shifting attention
between auditory and
visual stimuli
Neuroanatomy Handout #3: Brain Structures
• The midbrain (D) is
comprised of the following
structures:
– Superior colliculus:
helps process visual
info
– Inferior colliculus: helps
process auditory
information
– Substantia nigra –
involved in movement
Neuroanatomy Handout #3: Brain Structures
• Brain stem consists
of the:
– Medulla
– Pons
– Midbrain
– Some forebrain
structures
Neuroanatomy Handout #3: Brain Structures
• Forebrain: most
prominent part of
the mammalian
brain, consisting of:
– the outer cortex
(“cerebral cortex”)
– subcortical
regions
Neuroanatomy Handout #3: Brain Structures
• The limbic system is
associated with
motivation, emotion,
drives and aggression,
and includes:
– Olfactory bulb
– Hypothalamus
– Hippocampus
– Amygdala
• Olfactory bulbs send
info about smell to
cortex
Neuroanatomy Handout #3: Brain Structures
• Hypothalamus (F)
– Conveys messages to the
pituitary gland to trigger the
release of hormones
– Regulates autonomic nervous
system
– Involved in emotions and drives
vital to survival:
• Eating
• Drinking
• Sexual behavior
• Fear
• Feeling rewarded
Neuroanatomy Handout #3: Brain Structures
• Pituitary gland (G)hormone producing
gland found at the base
of the hypothalamus.
• AKA: “Master Gland”
Neuroanatomy Handout #3: Brain Structures
• Hippocampus is a large
structure of the limbic
system critical for
storing certain types of
memory.
• H.M., 1953
Neuroanatomy Handout #3: Brain Structures
• Amygdala: almond-shaped
structure important for:
– initial emotional response to
stimuli
– directing motivated
behavior at an appropriate
target
Neuroanatomy Handout #3: Brain Structures
• Forebrain structures
include:
– Thalamus (E) - relay
station for the sense
organs and main
source of input to the
cortex.
Neuroanatomy Handout #3: Brain Structures
• Basal Ganglia - comprised of the caudate nucleus, the
putamen and the globus pallidus.
– Associated with planning of motor movement, and
aspects of memory and emotional expression .
Neuroanatomy Handout #3: Brain Structures
• Nucleus basalis:
– receives input from
the hypothalamus
and basal ganglia
– key part of the brain’s
system for arousal,
wakefulness, and
attention
Neuroanatomy Handout #3: Brain Structures
• The ventricles are four fluid-filled cavities
within the brain containing cerebrospinal fluid.
The central canal is a fluid-filled channel in
the center of the spinal cord.
Neuroanatomy Handout #3: Brain Structures
• Cerebrospinal fluid (CSF) is a
clear fluid similar to blood
plasma found in the brain and
spinal cord:
– Provides “cushioning” for the
brain
– Reservoir of hormones and
nutrition for the brain and
spinal cord
– Choroid plexus: groups of
cells in the 4 ventricles that
continually manufacture CSF
Neuroanatomy Handout #3: Brain Structures
• Meninges: thin
membranes surrounding
brain and spinal cord
Neuroanatomy Handout #3: Brain Structures
The Cerebral Cortex
• The cerebral cortex is the most prominent part
of the mammalian brain and consists of the
cellular layers on the outer surface of the brain.
Neuroanatomy Handout #3: Brain Structures
The Cerebral Cortex
• The four lobes of the cerebral cortex:
•
•
•
•
Occipital lobe
Parietal lobe
Temporal lobe
Frontal lobe
2 hemispheres
Neuroanatomy Handout #3: Brain Structures
The Cerebral Cortex
• The Frontal lobe (H):
– involved in attention,
planning, decision-making,
etc.
– contains Broca’s area
(principal speech area) (H1)
– contains Precentral gyrus
(primary motor cortex) (H2),
responsible for control of
fine motor movement
Neuroanatomy Handout #3: Brain Structures
The Cerebral Cortex
• Parietal lobe (I) :
– involved in body sensations
– contains postcentral gyrus
(I1) (primary sensory area), a
main target for touch
sensations
Neuroanatomy Handout #3: Brain Structures
The Cerebral Cortex
• Temporal Lobe (J):
– involved in hearing
– also responsible for some
emotional and
motivational behaviors
– contains primary auditory
cortex (J1): Target for
auditory information and
essential for processing
spoken language
Neuroanatomy Handout #3: Brain Structures
The Cerebral Cortex
• Occipital lobe (K):
– Highly responsible for
visual processing
– contains striate cortex
or primary visual area
(K1)
– damage can result in
cortical blindness
Neuroanatomy Handout #3: Brain Structures
Central sulcus (L)
Longitudinal fissure (M)
Lateral fissure (N)
Neuroanatomy Handout #3: Brain Structures
• Corpus callosum
(O): large bundle of
axons joining the 2
hemispheres
• Anterior
commissure (P):
small bundle of
axons joining the 2
hemispheres
The Cerebral Cortex
• The binding problem refers to the question of how
the visual, auditory, and other areas of the brain
produce a perception of a single object.
– All areas of the brain communicate with each
other