Download The Nervous System - Division of Social Sciences

COGS17 ‐ 01‐The Nervous System
9/24/2009
The Nervous System
Mary ET Boyle, Ph.D.
Department of Cognitive Science
UCSD
What’s the big deal?
1
COGS17 ‐ 01‐The Nervous System
Detect
9/24/2009
Evaluate
Decide
Respond
Analysis of the nervous system to
understand the biological basis for
behavior.
 Modern studies

◦
◦
◦
◦
Neuroanatomists
Neurochemists
Neurophysiologists
Neuropsychologists
 Neuroscience – term introduced in mid-1960s
2
COGS17 ‐ 01‐The Nervous System
9/24/2009
The brain must know
what is happening
outside in the
environment.
•perceive
•remember
•decide
•act
sensory neurons
motor neurons
interneurons
Peripheral
Nervous
System (PNS)
Central
Nervous
System (CNS)
Sys
(C S)
Organization
3
COGS17 ‐ 01‐The Nervous System
9/24/2009
Detects/processes
environmental stimuli:
Somatic Nervous
System
Regulates internal
organs:
Autonomic
Nervous System
Organization of PNS
Detects environmental stimuli:
Somatic Nervous
System
Regulates internal organs:
Autonomic
Nervous System
Decision!
Central
nervous
system
4
COGS17 ‐ 01‐The Nervous System
9/24/2009
Brain
Spinal Cord
Components of the CNS
5
COGS17 ‐ 01‐The Nervous System
9/24/2009
Anterior
Posterior
Left
g
Right
D
l
Dorsal
Ventral
Anatomical directions
6
COGS17 ‐ 01‐The Nervous System
9/24/2009
Horizontal section—
Shows structures viewed from above/below
7
COGS17 ‐ 01‐The Nervous System
9/24/2009
Sagittal section—
Divides structures into right
and left parts
Coronal section (frontal section)—
Shows views from the front/back
8
COGS17 ‐ 01‐The Nervous System
9/24/2009
Review of Anatomical Directions
Anterior—toward
dog’s
Anterior
toward the front (e.g., dog
s nose)
Posterior—toward the rear (e.g., dog’s tail)
Ventral—toward the belly
Dorsal—toward the back
Rostral—toward the head
Caudal—toward the tail
Medial
toward the midline
Medial—toward
Lateral—away from the midline
Superior—above a structure
Inferior—below a structure
Fundamental cellular unit
 Purpose of neurons:

◦ receive
p
◦ process
◦ transfer
Information is made up of chemical or
electrical signals
 Unidirectional

Neurons
9
COGS17 ‐ 01‐The Nervous System
9/24/2009
Neurobiology of Cognition
COGS 17
Neurobiology of Cognition
COGS 17
10
COGS17 ‐ 01‐The Nervous System
9/24/2009
Four major types of synapses
11
COGS17 ‐ 01‐The Nervous System
9/24/2009
Three types of neurons
Some multipolar neurons
12
COGS17 ‐ 01‐The Nervous System
9/24/2009
Support Staff: Glia
More than just glue?
Glia,
short for
neuroglial
cells.
provide metabolic
Their purpose is to p
support, insulate, protect, reinforce,
repair, and cleanup damaged areas.
Mounting evidence suggests that glial
critical to
thinking and learning as neurons
cells may be nearly as
are.
Glia
13
COGS17 ‐ 01‐The Nervous System
9/24/2009
are much more numerous than neurons.
 outnumber neurons 2:1.
 are found in both the CNS and PNS.
 Neuroglia means “nerve
nerve glue
glue.”

Researchers have found that the average human cerebral cortex has
approximately two glial cells for every neuron (other brain regions
have up to 10 times as many). That’s a glia index of 2.0. The index
in comparable regions in rodents is 0.4, in worms 0.17. There is
work that supports the theory that a high concentration of glia may
actually boost the ability to think. So here’s something to think
about: the glia index in the cerebral cortex of dolphins is 3.0.
Glia …
14
COGS17 ‐ 01‐The Nervous System
9/24/2009
protoplasmic astrocytes
fibrous astrocytes
Basic classification of glial cells
microglial cells
oligodendrocytes
Spanish anatomist Pío del Río Hortega classified these cells. Hortega
made these drawings in 1920 with the help of a microscope’s camera
lucida.
15
COGS17 ‐ 01‐The Nervous System
9/24/2009
Neurobiology of Cognition
COGS 17
Multiple sclerosis (MS) is a
progressive central nervous system
disorder.
Localized oligodendrocyte
demyelination prevents affected nerve
cells from functioning properly.
In some cases, the demyelinated axons
completely fail to work.
16
COGS17 ‐ 01‐The Nervous System
9/24/2009
Neurobiology of Cognition
COGS 17
17
COGS17 ‐ 01‐The Nervous System
9/24/2009
Neurobiology of Cognition
COGS 17
Glia and neurons work together
Neurobiology of Cognition
COGS 17
18
COGS17 ‐ 01‐The Nervous System
9/24/2009
Neurobiology of Cognition
COGS 17
Zlokovic & Apuzzo: Neurosurgery 43(4):877-878, 1998.
Neurobiology of Cognition
COGS 17
19
COGS17 ‐ 01‐The Nervous System
9/24/2009
(PNS)
Peripheral
Nervous System
The Autonomic
Nervous System
The Somatic
Nervous System
The Somatic
Nervous System
Enables one to
interact with the
physical
environment.
Two types of nerves:
Efferent
Cranial
Spinal
neurons take
messages from
f
the CNS to
skeletal muscles
Afferent
neurons bring
g
messages from
the sensory
receptors to the
CNS
20
COGS17 ‐ 01‐The Nervous System
9/24/2009
Table 2.1: Klein/Thorne: Biological Psychology
© 2007 by Worth Publishers
21
COGS17 ‐ 01‐The Nervous System
9/24/2009
Efferent neurons
control glandular
activity
y and internal
organ functioning.
The Autonomic
Nervous System
Two divisions:
Sympathetic
Parasympathetic
S
Sympathetic
h i
Prepares the organism
to respond to
challenging or
dangerous conditions.
22
COGS17 ‐ 01‐The Nervous System
9/24/2009
CNS protection
23
COGS17 ‐ 01‐The Nervous System
9/24/2009
Ventricular System
24
COGS17 ‐ 01‐The Nervous System
9/24/2009
CNS: spinal cord
25
COGS17 ‐ 01‐The Nervous System

9/24/2009
Three main functions:
◦ Recognizing detected stimuli
◦ Analyzing the information
◦ Executing the appropriate response
The Central Nervous System:
The Brain
26
COGS17 ‐ 01‐The Nervous System
9/24/2009

Myelencephalon—contains the medulla
oblongata, which controls basic life functions
(e.g., respiration, heart rate, vomiting, salivation
Reticular formation (reticular activating
system)—begins in the medulla, extends to other
areas of the brain and is involved in arousal
 Metencephalon consists of two major structures:

◦ Pons—a “bridge” for many fibers passing from one side
of the brain to the other. Sensory fibers, fibers from the
cortex to cerebellum, and fibers that relay information on
sleep, arousal and dreaming pass through it.
◦ Cerebellum—involved in the development and
coordination of movement

Raphé system—plays a role in sleep and arousal
Hindbrain
Midbrain - mesencephalon
27
COGS17 ‐ 01‐The Nervous System
9/24/2009
Tectum (“roof”) relays visual and auditory information and
controls simple reflexes, eye and ear orientation movements
superior colliculi (“little hills”)—relays visual
information
inferior colliculi—relays auditory information
Tegmentum (“floor covering”)
substantia nigra—integration of voluntary movements
red nucleus —controls basic body movements
reticular formation —controls arousal and consciousness
brain stem—midbrain + hindbrain
(minus the cerebellum)
28
COGS17 ‐ 01‐The Nervous System
9/24/2009
Thalamus—major relay station for sensory information
Medial geniculate nucleus (MGN)—relays auditory information
Lateral ggeniculate nucleus (LGN)—relays
y visual information
Other nuclei connect to areas not involved in sensation, e.g., the ventrolateral nucleus receives information from
the cerebellum and relays it to the motor cortex.
29
COGS17 ‐ 01‐The Nervous System
9/24/2009
Hypothalamus—detects need states (e.g., hunger and thirst), controls
the autonomic nervous system, and controls pituitary hormone
production and release
The suprachiasmatic nucleus of the hypothalamus also is involved in
the control of biological rhythms.
Pituitary gland (hypophysis)—regulates other glandular activity of the body (often called the “master gland”)
Anterior pituitary gland (adenohypophysis)—produces several hormones including somatotropin, thyrotropin,
adrenocorticotropin and the gonadotropins
adrenocorticotropin,
Posterior pituitary (neurohypophysis)—releases oxytocin and antidiuretic hormone (ADH) which are produced in the
hypothalamus
30
COGS17 ‐ 01‐The Nervous System
9/24/2009
Limbic System
The limbic system governs emotions such as anger, happiness, and fear and is involved in the
storage and retrieval of memories.
The limbic system is a group of structures surrounding the brain stem.
The limbic system structures include the amygdala, cingulate gyrus, and hippocampus.
Basal Ganglia— have widespread connections to the cortex and forebrain and are involved in the initiation of
voluntary movements, maintaining muscle tone and posture
Parts of the basal ganglia include:
The caudate nucleus, the putamen, and the globus pallidus
The caudate nucleus and the putamen are referred to as the corpus striatum due to their appearance.
31
COGS17 ‐ 01‐The Nervous System
9/24/2009
32
COGS17 ‐ 01‐The Nervous System
9/24/2009
Somatosensory cortex —anterior portion of the parietal lobe.
lobe
Motor cortex —area of the frontal lobe anterior to the central sulcus.
The face and hands have a large amount of representation in these areas.
This representation allows for great sensitivity and motor control for these areas of the body.
33
COGS17 ‐ 01‐The Nervous System
9/24/2009
34
COGS17 ‐ 01‐The Nervous System
9/24/2009
35
COGS17 ‐ 01‐The Nervous System

9/24/2009
Neurons—Perform information processing and
communications functions of the nervous
system
◦
Consist of three major parts:
1. Soma (cell body)—contains nucleus,
mitochondria, and ribosomes
2. Dendrites—portions of the neuron that transmit
information toward the cell body (typically)
3. Axon—a structure on the neuron which
transmits information away from the cell body
Terms review

sensory neuron

motor neuron

interneuron

y
(
)
central nervous system
(CNS)

peripheral nervous system (PNS)
◦ A neuron that detects changes in the external or internal environment
and sends information about these changes to the central nervous
system.
◦ Sensory neurons carry information to the CNS
l
t d within
ithi the
th central
t l nervous system
t
th t controls
t l the
th
◦ A neuron located
that
contraction of a muscle or the secretion of a gland.
◦ They carry information from CNS to muscles to control their
functioning.
◦ A neuron located entirely within the central nervous system.
◦ Interneurons connect sensory and motor neurons or communicate with
other interneurons.
◦ The brain and the spinal cord.
◦ The part of the nervous system outside the brain and spinal cord,
including the nerves attached to the brain and the spinal cord.
Neurobiology of Cognition
COGS 17
36
COGS17 ‐ 01‐The Nervous System

Peripheral NS
9/24/2009

Central NS
◦ Nerve—a collection of
axons outside the
CNS
◦ Tract—a collection
of axons within the
CNS
◦ Ganglion (plural,
ganglia)—a collection
of cell bodies outside
the CNS
◦ Nucleus (plural,
nuclei)—a collection
of cell bodies within
the CNS
Cells of the Nervous System: Terminology

Presynaptic terminal—a swelling at the
end of the axon or telodendron
◦ Synaptic vesicles (contain neurotransmitter
substance)
◦ Synapse—point of functional contact between a
neuron and its target
◦ Synaptic cleft—small space which separates the
presynaptic terminal from its target
Cells of the Nervous System: Terminology
37
COGS17 ‐ 01‐The Nervous System





9/24/2009
Axodendritic—the axon synapses with dendrites of
another neuron
Axosomatic—the axon synapses
y p
with the cell body
y of
another neuron
Dendrodendritic synapse—occurs when the dendrites of
one neuron synapses with the dendrites of another
neuron
Axoaxonic synapse—the axon of one neuron synapses
with the axon of another neuron
Neuromuscular junction—the axon synapses with a
l
muscle
Cells of the Nervous System: Types of Synapses

Pituitary gland (hypophysis)—regulates other
glandular activity of the body (often called the
“master gland”)

Anterior pituitary gland (adenohypophysis)—
(adenohypophysis)
produces several hormones including somatotropin,
thyrotropin, adrenocorticotropin, and the
gonadotropins

Posterior pituitary (neurohypophysis)—releases
oxytocin and antidiuretic hormone (ADH) which are
produced in the hypothalamus
CNS—The Brain, Forebrain:
CNS—
The Diencephalon
38
COGS17 ‐ 01‐The Nervous System
9/24/2009
CNS—The Brain, Forebrain:
The Telencephalon

The telencephalon (end brain) consists of
three parts:
◦ Limbic system
◦ Basal ganglia
◦ Cerebral cortex
CNS—The Brain, Forebrain:
The Telencephalon

Limbic System
◦ The limbic system governs emotions such as
anger, happiness, and fear and is involved in
the storage and retrieval of memories.
◦ The limbic system is a group of structures
surrounding
su
ou d g the
t e brain
b a stem.
ste
◦ The limbic system structures include the
amygdala, cingulate gyrus, and hippocampus.
39
COGS17 ‐ 01‐The Nervous System


9/24/2009
Basal Ganglia—have widespread connections to
the cortex and forebrain and are involved in the
initiation of voluntary movements, maintaining
muscle tone and posture
P
Parts
off the
h basal
b
l ganglia
li include:
i l d
◦ The caudate nucleus, the putamen, and the globus
pallidus

The caudate nucleus and the putamen are
referred to as the corpus striatum due to their
appearance.
CNS—The Brain, Forebrain:
CNS—
The Telencephalon

Cerebral Cortex—the convoluted outer layer of
the forebrain that processes sensory information,
controls thinking, decision making, stores and
retrieves memory, and initiates motor responses

The cortex is divided into two hemispheres
(connected by the corpus callosum) and each
hemisphere has four lobes.
CNS—The Brain, Forebrain:
CNS—
The Telencephalon
40
COGS17 ‐ 01‐The Nervous System

9/24/2009
soma
◦ The cell body of a neuron, which contains the nucleus.

dendrite
◦ The branched, treelike structure attached to the soma of a
neuron; receives information from the terminal buttons of
other neurons.

synapse
◦ A junction between the terminal button of an axon and the
membrane of another neuron.

axon
◦ The long, thin, cylindrical structure that conveys information
from the soma of a neuron to its terminal buttons.
Neurobiology of Cognition
COGS 17

multipolar neuron
◦ A neuron with one axon and many dendrites attached to
its soma.

bipolar neuron
◦ A neuron with one axon and one dendrite attached to its
soma.

pseudounipolar neuron
◦ A neuron with one process attached to its soma; the
process divides, with one branch receiving sensory
information and the other sending the information into the
central nervous system.

terminal button
◦ The bud at the end of a branch of an axon; forms
synapses with another neuron; sends information to that
neuron.
Neurobiology of Cognition
COGS 17
41
COGS17 ‐ 01‐The Nervous System

9/24/2009
neurotransmitter
◦ A chemical that is released by a terminal button; has
excitatory or inhibitory effect on another neuron.

membrane
◦ A structure consisting principally of lipid molecules that
defines the outer boundaries of a cell and also constitutes
many of the cell organelles, such as he Golgi apparatus.

nucleus
◦ A structure in the central region of a cell, containing the
nucleolus and chromosomes.

nucleolus
◦ A structure within the nucleus of a cell that produces the
ribosomes.
Neurobiology of Cognition
COGS 17

ribosome
◦ A cytoplasmic structure, made of protein, that serves as the
site of production of proteins translated from mRNA.

chromosome
◦ A strand of DNA
proteins found in the
DNA, with associated proteins,
nucleus; carries genetic information.

deoxyribonucleic acid (DNA)
◦ A long, complex macromolecule consisting of two
interconnected helical strands; along with associated
proteins, strands of DNA constitute the chromosomes.

gene
◦ The functional unit of the chromosome, which directs
synthesis of one or more proteins.
Neurobiology of Cognition
COGS 17
42
COGS17 ‐ 01‐The Nervous System

9/24/2009
messenger ribonucleic acid (mRNA)
◦ A macromolecule that delivers genetic information
concerning the synthesis of protein from a portion of a
chromosome to a ribosome.

enzyme
◦ A molecule that controls a chemical reaction
reaction, combining two
substances or breaking a substance into two parts.

non-coding RNA (ncRNA)
◦ A form of RNA that does not encode for protein, but has
functions of its own.

y p
cytoplasm
◦ The viscous, semiliquid substance contained in the interior of
a cell.
Neurobiology of Cognition
COGS 17

mitochondrion
◦ An organelle that is responsible for extracting energy from
nutrients.

adenosine triphosphate (ATP)
◦ A molecule of prime importance to cellular energy metabolism; its
breakdown liberates energy.

endoplasmic reticulum
◦ Parallel layers of membrane found within the cytoplasm of a cell.
Rough endoplasmic reticulum contains ribosomes and is involved
with production of proteins that are secreted by the cell. Smooth
endoplasmic reticulum is the site of synthesis of lipids and provides
channels for the segregation of molecules involved in various
cellular processes.

Golgi apparatus
◦ A complex of parallel membranes in the cytoplasm that wraps the
products of a secretory cell.
Neurobiology of Cognition
COGS 17
43
COGS17 ‐ 01‐The Nervous System

9/24/2009
exocytosis
◦ The secretion of a substance by a cell through means of
vesicles; the process by which neurotransmitters are
secreted.

lysosome
◦ An organelle surrounded by membrane; contains enzymes
that break down waste products.

cytoskeleton
◦ Formed of microtubules and other protein fibers, linked to
each other and forming a cohesive mass that gives a cell its
shape.

microtubule
◦ A long strand of bundles of protein filaments arranged
around a hollow core; part of the cytoskeleton and involved
in transporting substances from place to place within that
cell.
Neurobiology of Cognition
COGS 17

Glial cells
◦ One-tenth the size of neurons
◦ Ten times as numerous as neurons

Types
yp of Glial cells
◦ Astrocytes—provide physical support to
neurons, nourishment and other functions.
 New evidence suggests that astrocytes also
integrate neuronal messages and release
neurotransmitters that affect the sensitivity of
synapses.
Cells of the Nervous System: Glial cells
44
COGS17 ‐ 01‐The Nervous System

9/24/2009
Types of Glial cells (cont.)
◦ Microglial cells—remove debris
◦ Oligodendrocytes
Oligodendrocytes—produce
produce myelin which
covers the axons of neurons in CNS
◦ Schwann cells—produce myelin which covers
the axons of neurons in PNS


Multiple sclerosis—destroys
oligodendrocytes
axoplasmic transport
◦ An active process by which substances are propelled along
microtubules that run the length of the axon.

anterograde
◦ In a direction along an axon from the cell body toward the
terminal buttons.

retrograde
◦ In a direction along an axon from the terminal buttons
toward the cell body.

glia
li
◦ The supporting cells of the central nervous system.
Neurobiology of Cognition
COGS 17
45
COGS17 ‐ 01‐The Nervous System

9/24/2009
astrocyte
◦ A glial cell that provides support for neurons of the central
nervous system, provides nutrients and other substances,
and regulates the chemical composition of the extracellular
fluid.

phagocytosis
h
◦ The process by which cells engulf and digest other cells or
debris caused by cellular degeneration.

oligodendrocyte
◦ A type of glial cell in the central nervous system that forms
myelin sheaths.

myelin sheath
◦ A sheath that surrounds axons and insulated them,
preventing messages from spreading between adjacent
axons.
Neurobiology of Cognition
COGS 17

node of Ranvier
◦ A naked portion of a myelinated axon, between adjacent
oligodendroglia or Schwann cells.

microglia
c og a
◦ The smallest of glial cells; act as phagocytes and protect the
brain from invading microorganisms.

Schwann cell
◦ A cell in the peripheral nervous system that is wrapped
around myelinated axon, providing one segment of its myelin
sheath.
Neurobiology of Cognition
COGS 17
46
COGS17 ‐ 01‐The Nervous System
9/24/2009
Skull—outer bony covering that encases
the brain
 Vertebral Column—outer bony covering
that encases the spinal cord
 Meninges

◦ Dura matter
◦ Arachnoid matter
◦ Pia mater

Ventricular system
y
The Protective Features of the CNS

blood-brain barrier
◦ A semipermeable barrier between the blood and
the brain produced by the cells in the walls of the
brain’s capillaries.

area postrema
◦ A region of the medulla where the blood-brain
barrier is weak; poisons can be detected there and
g
can initiate vomiting.
Neurobiology of Cognition
COGS 17
47