Introduction to Psychology Brain and Behavior. Nervous System CNS: Brain and Spinal Cord Peripheral...
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Transcript of Introduction to Psychology Brain and Behavior. Nervous System CNS: Brain and Spinal Cord Peripheral...
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
Occipital lobes
Temporal lobes
Involved in voluntary movement, thinking, personality, and intentionality or purpose
Function in vision
Active role in hearing, language processing, and memory
Parietal lobesRoles 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:
PTSD: reduced size of the hippocampus
Depression: 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