Download intro to psych brain and behavior

Introduction to Psychology
Brain and Behavior
Nervous System


CNS: Brain and Spinal Cord
Peripheral Nervous System:
network of nerves that carries
information to and from the nervous
system
Peripheral Nervous System

Somatic System: carries messages to
and from sense organs and skeletal
muscles

Controls voluntary behavior
Peripheral Nervous System

Autonomic Nervous System: glands
and organs; “automatic functions”

Heartbeat, digestion
Peripheral Nervous System


Sympathetic: fight or flight; prepares
for action
Parasympathetic: quiets the body;
lowers arousal
Neurons

Nerve cells in the brain


Carry messages; activate muscles and
glands
100 billion neurons in the brain
The Neuron
Fig. 3.8
Parts of the Neuron


Dendrites: receives messages from
other neurons
Soma: receives messages; sends nerve
impulse down the axon
Parts of the Neuron


Axon: thin fiber leading to the terminal
buttons; nerve impulses travel down the
axon; carries messages
Myelin sheath: fatty layer covering the
axon that helps nerve impulses move
faster
Parts of the Neuron

Synapse: the microscopic space
between the neurons over which
messages pass


Neurotransmitters travel across the axon
Ions: electrically charged molecules found inside
and outside the neuron, with + or - charges
Resting Potential

Electrical charge of an inactive neuron


-70 mv
Messages from other neurons raise or
lower the resting potential
Threshold

If the charge raises to -50 mv, the
neuron reaches its threshold

Threshold=trigger point for firing

Ready to fire
Neural Firing


An action potential (nerve impulse)
sweeps down the axon
Ion channels open and sodium ions rush in
After the action potential....



Positive ions flow back out; the neuron
becomes negatively charged again
Resting state is restored
After firing, the neuron dips below
resting level and is less willing to fire
Firing...


Firing is an all or nothing event
The neuron either fires, or doesn’t fire

It take 1/1000 of a second for a neuron to
fire; on average, they fire between 1-400
times per second
Neurotransmitters


Chemicals that alter activity in the
neurons
Neurotransmitters travel from the
terminal buttons across the synapse,
and connect to special receptors sites
on the dendrites and soma of the next
neuron
Neurotransmitters

Neurotransmitters can excite or inhibit
firing
Types of Neurotransmitters





Dopamine: too little=Parkinson’s, too
much=schizophrenia
Acetylcholine: activates muscles
Serotonin: deficiency associated with
depression/anxiety
Neuropeptides: influence memory, pain,
emotion, and mood
Endorphins: released by the pituitary glad;
lessens pain
The Brain

Right and Left hemispheres

Lateralization

Divided by the corpus callosum
Left and Right Hemispheres
Left:
Detail oriented
Speech and
language
Calculating
Understands one
word at a time, not
the big picture





Right:
Non-verbal
Face recognition
Express/detect
emotion
Understanding
speech
context/nuances of
language





The Brain’s Four Lobes
Fig. 3.7
Functions of Lobes of the Cortex
Frontal lobes
Involved in voluntary movement,
thinking, personality, and
intentionality or purpose
Occipital lobes Function in vision
Temporal lobes
Parietal lobes
Active role in hearing, language
processing, and memory
Roles in registering spatial location,
attention, and motor control
The Brain

Recent research:

Both heredity and environment shape the
brain

The role of experience and brain plasticity
Dendritic Spreading
Fig. 3.11
Pruning

Changes to the dendrites and synapses

Connections are formed and terminated
Experience and the Brain

Exposure to trauma:


Depression:


PTSD: reduced size of the hippocampus
Parts of the brain atrophy over time
Addiction:

Changes in neurotransmitters
Experience and the Brain


Mice in deprived vs. enriched
environments: differences in brain
weight, neural connections and activity
Children reared in deprived
environments have depressed brain
activity (i.e. Romanian orphans)

Can be reversed; brain plasticity/resilience
The Brain in Adolescence

Adolescent emotions —

Areas of the brain involved in emotional
regulation are still growing/changing

Poor self-control; seek rewards and pleasure

Risk taking

Lack of practical experiences; immature judgment
Alcoholism




Alcohol doesn’t “kill” neurons, but
damages the dendrites
Affects communication between
neurons
Frontal lobe and limbic system
Brain may atrophy