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COURSE NOTES: Introductory Psychology

Psych101 graphic

Chapter 2:

Neuroscience and Behavior

Notes for Psychology 101: based on Myers's text, Exploring Psychology, with supplements and modifications by the instructor, Prof. Cloninger.

denotes a term that you should know how to define, and to recognize and give examples.

denotes an important person. You should remember this person's name and what (s)he has done.

denotes an important research finding.

denotes an issue that you should be able to discuss or explain.

Brain function and malfunction has many implications:

learning & learning disabilities
mental disorders
addiction
consciousness
etc...

Possibly including:

deja vu
the experience of having an invisible double of your own self!

Biological psychology studies the links between biology and behavior

Philosophers discuss the "mind-body problem."

phrenology: Franz Gall's theory that "bumps on the skull could reveal our mental abilities and our character traits" (Myers, 2005, p. 37)

Did you know?

All multicellular animals except one kind have a nervous system in one form or another, as a system for regulating body functions and coordinating responses to the environment.
Sponges do not have a nervous system.
(I didn't even know that sponges were animals!)

Nervous system

peripheral

central

Neurons

the basic cell of the nervous system
sensory (incoming)
motor (outgoing)
interneurons (CNS; between sensory & motor)

reflex

one well-known reflex [graphic of a knee-jerk reflex]

Generating a neural impulse

dendrite (incoming)

cell body

axon (outgoing)

Myelin sheath

on axon
speeds nerve impulse

Action potential

threshold

rapid depolarization (negative charge inside cell becomes neutral, even briefly positive)
all-or-none (like a light switch, not a dimmer switch!)
sodium ions flow into cell

Needless to say, neural impulses don't create a permanent change in the neuron. There is "repolarization", as potassium ions flow out of the cell. Later, sodium and potassium are "pumped" back to their original positions.

This permits the neuron to fire again. Some can fire as many as 800 impulses per second!!!

myelin sheath

covers many neurons
speeds nerve impulse
formed by fatty support cells (glial cells) wrapped around neuron
gaps (nodes of Ranvier)
makes brain areas look white (instead of gray)
Some researchers believe that improper myelinization during development produces learning disorders.

Neurotransmitters

chemical messengers
in synapse (space between neurons)
acetylcholine (ACh), in motor neurons (& more)
endorphins (endogenous morphine): opiate-like; control pain
Neurotransmitters carry a neuron's message to another neuron, or sometimes to a gland (which secretes a hormone) or muscle cell (which contracts).

Neurotransmitters have either of 2 effects:

excitatory
- increases likelihood next cell will fire
- cause sodium to enter the cell
inhibitory
- decreases likelihood next cell will fire
- cases chloride to enter the cell

Medicines and drugs affect neurotransmitters

agonist: substitutes for neurotransmitter
antagonist: blocks neurotransmitter

neural pathways use specific neurotransmitters (see Myers, 2005, p. 40 for photos)

acetylcholine

messages from neurons to muscle tissue
blocked by antagonist curare
South American Indians use this on hunting arrows as a tranquilizer

dopamine

increased by drugs that treat Parkinson's disease ("palsy")
decreased by drugs that treat schizophrenia

serotonin

depression
suicide
murder
impulsive disorders
sleep disorders
addictions
pain
associative learning

norepinephrine

arousal
alertness
abnormally high in maternally deprived monkeys who are stressed or given amphetamine drugs

Divisions of the Nervous system

Central

brain
spinal cord

Peripheral

somatic (sensory & motor)
autonomic (self-regulating)
- sympathetic (arousing)
- parasympathetic (calming)

Brain

The cerebral cortex is larger among "higher" animals. [graphic image]

Lower-Level Brain Structures

The Brainstem

old brain

central core

medulla (near spinal cord): heartbeat and breathing; left-right crossover

reticular formation (arousal, attention)

The Thalamus

thalamus (sensory switchboard)

The Cerebellum

cerebellum: coordinates movement; some learning & memory

The Limbic System

emotion, motivation, and memory
amygdala: influences aggression and fear

hypothalamus: influences hunger, thirst, body temperature, and sexual behavior

affects pituitary, endocrine system
emotion and reward

Brain measurement

EEG

brain waves
electrical waves
outside of scalp
rough indicator of activity in various areas
wake/sleep
brain damage
biofeedback
most primitive technique

CT scan

"computerized tomography"
x-ray series
3-dimensional picture of brain

MRI

"magnetic resonance imaging"
shows structures
magnetic field aligns hydrogen atoms in brain
turning off magnetic field makes the atoms bounce back to their normal condition, which produces magnetic signals, displayed on a computer
"functional MRI" shows moment to moment changes

PET scan

"positron emission tomography"
activity
glucose consumption of cells
radioactive glucose injection

Brain imaging shows distinctive structure and/or function for:

autism
Down syndrome
schizophrenia
Tourette's syndrome
dyslexia
attention deficit hyperactivity disorder
depression

Cerebral Cortex

"covering"
thin surface, folded (convoluted)
neurons and glial cells
largely consists of association areas
lobes of the cerebral hemisphere: frontal, parietal, occipital, temporal

frontal lobes

speaking
muscle movements
plans
judgments
case: Phineas Gage
motor cortex: voluntary movements
where? forehead
contains Broca's area, permitting speech
abstract functioning, including planning, inhibiting behavior, and "personality"
damaged in historic case of Phineas Gage

parietal lobes

sensory cortex
incoming information from eyes, ears, and other sensory organs
where? top rear
incoming neural messages to the motor cortex can give "phantom limb" sensations

occipital lobes

visual areas
where? back of head

temporal lobes

auditory areas
where? above ears
facial recognition area
contains Wernicke's area (word comprehension)

association areas

most of cortex
frontal lobe: planning
language
Broca's area: speaking ( in frontal lobe)
Wernicke's area: word comprehension ( in temporal lobe)

Brain Reorganization

plasticity
development to recover from damage
compensation for lost brain areas or lost senses
cannot replace neurons [but research continues!]
characteristic of young brains
treatment possibilities?

Oliver Sacks, on brain-damaged patients:
"While one may be horrified by the ravages of developmental disorder or disease, one may sometimes see them as creative too--for if they destroy particular paths, particular ways of doing things, they may force the nervous system into making other paths and ways, force on it an unexpected growth and evolution. This other side of development or disease is something I see, potentially, in almost every patient." (Sacks, 1995, p. xvi)

Our Divided Brains ("split brain")

lesion between two cerebral hemispheres
corpus callosum
split-brain
left/right crossover
left hemisphere: language (including sign language)
right hemisphere: music and art

[graphic]: HE|ART (right/left hemisphere)

stimulus: "heart"
verbal report, left hemisphere: sees "art"
pointing (left hand) right hemisphere: points to "he"
(Of course, this wouldn't happen in a person with a normal corpus callosum, since both left and right hemispheres would get all information.)

dissociated functions in patients with split brains (Myers, 2005, pp. 60-61)

e.g., recognizing objects verbally (left hemisphere) vs. by touch (right hemisphere, left hand)

specialization in intact adults and babies

left hemisphere: literal language; baby language (right side of mouth)