Week 1: Biological Perspective of
Learning and Behavior
Learning: A biological process whereby a
relatively permanent change in behavior
occurs as a result of experience.
Behavior: adaptive in a sense that they
are the product of our biology and can be
shaped by our experience
Biological Perspective: The study of Laarning and Behavior from the
perspective of neuroanatomy and physiology.
The Neuron
Types of Neurons
Sensory(or
afferent)
neurons: send
information
from sensory
receptors (e.g.,
in skin, eyes,
nose, tongue,
ears) TOWARD
the central
nervous system.
Motor (or
efferent)
neurons: send
information
AWAY from the
central nervous
system to
muscles or
glands
Interneurons:
send
information
between
sensory
neurons and
motor neurons.
Most
interneurons
are located in
the central
nervous
system.
Anatomy of a Neuron:
Axon: Take information away from cell body
Dendrites: Bring information to the cell body
Nucleus - contains genetic material
(chromosomes) including information for cell
development and synthesis of proteins
necessary for cell maintenance and survival.
Covered by a membrane.
Nucleolus - produces ribosomes necessary
for translation of genetic information into
proteins
Nissl Bodies - groups of ribosomes used for
protein synthesis.
Endoplasmic reticulum (ER) - system of
tubes for transport of materials within
cytoplasm. Can have ribosomes (rough ER)
or no ribosomes (smooth ER). With
ribosomes, the ER is important for protein
synthesis.
Golgi Apparatus - membrane-bound
structure important in packaging peptides
and proteins (including neurotransmitters)
into vesicles
Microfilaments/Neurotubules - system of
transport for materials within a neuron and
may be used for structural support.
Mitochondria - produce energy to fuel cellular
activities.
Function of a Neuron
Action Potential
An action potential occurs when a
neuron sends information down an
axon, away from the cell body.
Neuroscientists use other words,
such as a "spike" or an "impulse" for
the action potential. The action
potential is an explosion of electrical
activity that is created by a
depolarizing current. This means that
some event (a stimulus) causes the
resting potential to move toward 0
mV. When the depolarization reaches
about -55 mV a neuron will fire an
action potential. This is the threshold.
If the neuron does not reach this
critical threshold level, then no action
potential will fire.
Neurons send
messages
electrochemically. This
means that chemicals
cause an electrical
signal. Chemicals in the
body are
"electrically-charged" --
when they have an
electrical charge, they
are called ions. The
important ions in the
nervous system are
sodium and potassium
(both have 1 positive
charge, +), calcium (has
2 positive charges, ++)
and chloride (has a
negative charge, -).
There are also some
negatively charged
protein molecules
Resting Potential
When a neuron is not
sending a signal, it is "at
rest." When a neuron is at
rest, the inside of the neuron
is negative relative to the
outside. Although the
concentrations of the
different ions attempt to
balance out on both sides of
the membrane, they cannot
because the cell membrane
allows only some ions to pass
through channels (ion
channels). At rest, potassium
ions (K+) can cross through
the membrane easily. Also at
rest, chloride ions (Cl-)and
sodium ions (Na+) have a
more difficult time crossing.
The negatively charged
protein molecules (A-) inside
the neuron cannot cross the
membrane.
In addition to these selective
ion channels, there is a
pump that uses energy to
move three sodium ions out
of the neuron for every two
potassium ions it puts in.
Finally, when all these forces
balance out, and the
difference in the voltage
between the inside and
outside of the neuron is
measured, you have the
resting potential. At rest,
there are relatively more
sodium ions outside the
neuron and more potassium
ions inside that neuron.
Rate of firing:
Also, when the
threshold level is
reached, an
action potential
of a fixed sized
will always
fire...for any
given neuron,
the size of the
action potential
is always the
same. There are
no big or small
action potentials
in one nerve cell
- all action
potentials are
the same size.
Therefore, the
neuron either
does not reach
the threshold or
a full action
potential is fired
- this is the "ALL
OR NONE"
principle.
The Brain
Amygdala: neutral centers in the
limbic system linked to emotion
Hippocampus: a structure in the
limbic system linked to memory
Corpus callosum: axon fibers
connecting two cerebral
hemispheres
Thalamus: relays messages between
lower brain centers and cerebral cortex
Hypothalamus: controls maintenance functions such as
eating; helps govern endocrine system; linked to emotion
and reward.
Pituitary: master endocrine gland
Reticular formation: helps control
arousal.
Medulla: controls heartbeat and breathing.
Spinal Cord: Pathway for neural fibers traveling to
and from brain; controls simple reflexes.
Cerebellum: coordinates voluntary movement and
balance.
Cerebral cortex: ultimate control and information processing center.
The
Synaptic
Self
Joseph
LeDoux Is
your
psychology
the product
of neural
connections?
That is, are
your
experiences
and
memories
just neural
connections?
If so, does
that change
our
experiences
with each
other or with
God?
Evolution
Evolution as the mechanism of
change in the brain as well as the
capacity to learn
Learning provide successful foraging
and thus, reproductive fitness
Remember, this happens at the level
of the gene and thus, influences
neuroanatomy and physiology
Preparedness/ Contra-preparedness:
Classically Conditioned fear of snakes, not
bunnies (Mineka, Davidson, Cook, & Keir,
1984)
Charles Darwin
(1859) – Origin of
Species Five Facts
and Three Inferences
Fact: Populations
grow exponentially
Fact: Populations
ultimately stabilize
Fact: Populations live
in areas with limited
resource
Inference:
Competition for
limited resources
Fact: Individuals are
unique
Fact: Uniqueness is
heritable
Inference:
Differential survival
rates or Natural
Selection
Inference: Natural Selection over
successive generations results in
Evolution