Chapter 2
Neuroscience and
Behavior
Neural Communication
• Biological/neuroscience
Psychology
–branch of psychology concerned
with the links between biology
and behavior
–Want a better understanding of
sleep and dreams, depression and
schizophrenia, hunger, sex, stress
and disease
Neural Communication
• Neuron
– a nerve cell
– the basic building block of the nervous system
• Dendrite
– the bushy, branching extensions of a neuron that
receive messages and conduct impulses toward
the cell body
– Brings in info
• Axon
– the extension of a neuron, ending in
branching terminal fibers, through which
messages are sent to other neurons or to
muscles or glands
• Myelin [MY-uh-lin] Sheath
– a layer of fatty cells that encase the fibers
of many neurons
– Speeds up neutral impulses
– MS
Neural Communication
• Action Potential
– a neural impulse; a brief electrical charge
(Ion) that travels down an axon
– Outside the Axon= positive ions
– Inside the Axon= negative ions
– Even positive and negative= resting potential,
which acts like a gate .
– Depolarization= unfreezes or ungates the
axon allowing the message to go through
– Refractory period= resting period, when extra
atoms are pushed out
– Some signals excite and some inhibit
• Threshold
– the level of stimulation required to trigger
a neural impulse
– All or nothing
Neural Network
Neural Communication
• Synapse
– junction between the axon tip of the sending
neuron and the dendrite or cell body of the
receiving neuron
– tiny gap at this junction is called the synaptic gap
or cleft
• Neurotransmitters
– chemical messengers that cross the synaptic gaps
between neurons
– Excite or inhibit
– Lock and key
– Reuptake
•
•
Neurotransmitters
• Each pathway uses different neurotransmitters,
each neurotransmitter has a different function
• Acetylcholine ( ACH)
- muscle contraction, learning and memory
– Alzheimer's
• Endorphins– “morphine within”
– natural, opiatelike neurotransmitters
– linked to pain control and to pleasure
• Dopamine- alertness and movement
– Parkinson's
– schizophrenia
Neurotransmitters
• Serotonin- mood, hunger,sleep and arousal
• depression
• Norepinephrine- controls alertness and
arousal
• Gamma-aminobutryic acid (GABA)inhibitory neurotransmitter
• Glutamate- A major excitatory neruo.,
memory
– Migraines
– Seizures
Dopamine pathways
How Drugs Effect
Neurotransmitters
• Many drugs mimic the
neurotransmitter
–Agonists excite
–Antagonists inhibit
Neurotransmitter
molecule
Receptor site on
receiving neuron
Receiving cell
membrane
Agonist mimics
neurotransmitter
Antagonist
blocks
neurotransmitte
The Nervous
System
The Nervous System
Nervous
system
Central
(brain and
spinal cord)
Peripheral
Autonomic (controls
self-regulated action of
internal organs and glands )
Skeletal (controls
voluntary movements of
skeletal muscles )
Sympathetic
(arousing )
Parasympathetic
(calming )
The Nervous System
• The Nervous System
–Body’s communication system
–2 parts- Central and Peripheral
–The Nervous System uses 3
types of neurons
• 1. Sensory
• 2. Interneurons
• 3. Motor neurons
Central Nervous System
•
Peripheral Nervous System
•
•
The Peripheral System
2 components
–1. Somatic Nervous Systemcontrols our skeletal muscles
–2.Autonomic Nervous Systemglands,muscles of our internal organs
–Heartbeat, digestion, hormones
–1. Sympathetic Nervous Systemdefense actions ( increases heartbeat,
muscles contract…..)
–2. Parasympathetic- it conserves energy
Central Nervous System ( CNS)
• Spinal Cord and Brain
• Spinal Cord connects peripheral
system to the brain
• Reflexes
Brain
Sensory neuron
(incoming information)
Interneuron
Motor neuron
(outgoing
information)
Muscle
Skin
receptors
Spinal cord
The Brain
Tools of Discovery
• Manipulating the brain –
• Lesions
• electromagnetic charges
• chemical and magnetic stimulation
• Clinical Observations
- looking at damaged brains
• Recording Electrical Activity EEG (
electroencephslogram)
• an amplified recording of the waves of
electrical activity that sweep across the
brain’s surface
EEG
Tools of Discovery
• Neuroimaging– CT ( Computed tomography) Scan• X- Ray photographs
– PET ( Positron emission tomography) Scan
• Looks at sugar glucose to determine brain
activity
– “HOT SPOTS”
– MRI- ( Magnetic Resonance Imaging)
• generated images that distinguish among
different types of soft tissue; allows us to see
structures within the brain.
PET Scan
PET Scan
MRI
The Brain
Lower Level Brain Structure
•
Lower Brain
Lower Brain• performs life saving operations
freeing the higher brain regions to
think, dream, memorize..
• We are unaware of most of its
functions
Lower Level Brain Structure
The Brainstem
1. Brainstem-
• where spinal cord enters the skull
• Crossover point for nerves
• responsible for automatic survival functions
2. Medulla- Heartbeat and breathing
Lower Level Brain Structure
The
Brainstem
3. Reticular Formation• Filter and relay station
• Controls arousal
4. Thalamus-
• Sensory input
station,except smell
• Receives higher brains
replies
• Controls electrical
cycles. Slows during
sleep;speeds up while
awake
Lower Level Brain Structure
The Brainstem
• 5. The Cerebellum
• Coordinates voluntary movements
–Balancing, walking……….
• Nonverbal voluntary movement
• 6. Pons
– Regulates sleep
The Limbic System
•
The Limbic System
–associated with emotions such as
fear and aggression and drives
such as those for food and sex
–includes the hippocampus,
amygdala, and hypothalamus.
The Limbic System
• 1. Hippocampus• Processes memory
• Forms new memories
• 2. Amygdala• Aggression and fear
The Limbic System
• 3. Hypothalamus-
– Controls pituitary gland (hormones)
– directs several maintenance activities
• eating
• drinking
• body temperature
– Triggers autonomic nervous system
– Pleasure Center
– Reward Deficiency Syndromealcoholism, binge drinking, drug abuse
Psychosurgery?
• What is psychosurgery?
The Cerebral Cortex
• Thin layer covering your cerebral
hemispheres- wrinkly thing
• Neural cells
• Controls body and info
• The bigger the better
The Cerebral Cortex
Structure and Functions
1. Each hemisphere is divided up into 4
lobes
•
•
•
•
Frontal
Occipital
Temporal
Parietal
2. Glial Cells- -
• neural nannies
• Support the 22 billion nerve cells
The Cerebral Cortex
1. Frontal Lobe- speaking, muscle
movement, making plans, judgments
• Motor Cortex- outgoing messages
to the body
The Cerebral Cortex
2.Parietal Lobe- sensory cortex
• Sensory Cortex-registers and
processes body sensations
• Receives info from skin receptors
• More sensitive= bigger area
3.Occipital Lobe- receives visual from
opposite sides
The Cerebral Cortex
4.Temporal Lobes- receive auditory
simulation from opposite sides
• Don’t need real sounds
Functional
MRI scan of
the visual
cortex
activated by
light shown
in the
subject’s
eyes`
Visual
cortex
Auditory
cortex
The Cerebral Cortex
• Association Areas-
areas of the
cerebral cortex that
are not involved in
primary motor or
sensory functions
involved in higher
mental functions
such as learning,
remembering,
thinking, and
speaking
Association Areas
• Aphasia
– impairment of language, usually caused by left
hemisphere damage either to Broca’s area (impairing
speaking) or to Wernicke’s area (impairing
understanding)
• Broca’s Area
– an area of the left frontal lobe that directs the muscle
movements involved in speech
• Wernicke’s Area
– an area of the left temporal lobe involved in language
comprehension
• Angular Gyrus-auditory sounds
The Cerebral Cortex
Brain activity when hearing,
seeing, and speaking words
Brain Reorganization
• Plasticity- neural tissue can
reorganize in response to
damage
• Orgasm in foot
• Most plastic when young
Our Divided Brain
Corpus callosum
• Corpus Callosum
– largest bundle of
neural fibers
– connects the two
brain hemispheres
– carries messages
between the
hemispheres
Split Brain
• a condition in which the two
hemispheres of the brain are
isolated by cutting the connecting
fibers (mainly those of the corpus
callosum) between them
• “alien hand syndrome”
Hemispheric Differences
• Specialization
• Each hemisphere has its own
specialties
• Most people are stronger in one
hemisphere
• Left- logical, verbal, sequential
• Right- emotional, expressive, better
at spatial relations
Handedness
• 90% right handed
Percentage of 14%
left-handedness
12
The percentage of
lefties sharply
declines with age
10
8
6
4
2
0
10
20
30
40
50
Age in years
60
70
80
90
Neural and Hormonal Systems
• Endocrine System
– the body’s “slow”
chemical
communication
system
– a set of glands that
secrete hormones into
the bloodstream
Endocrine System
• Hormones
– chemical messengers, mostly those
manufactured by the endocrine
glands, that are produced in one
tissue and affect another
– Growth, reproduction, metabolism,
mood………
Endocrine System
• Adrenal Glands
– a pair of endocrine glands just above
the kidneys
– secrete the hormones epinephrine
(adrenaline) and norepinephrine
(noradrenaline), which help to arouse
the body in times of stress
– Increases heart beat, blood pressure,
blood sugar….. Gives us energy
Endocrine System
• Pituitary Gland
– under the influence of the
hypothalamus, the pituitary regulates
growth and controls other endocrine
glands
– Master gland
Other Hormones /Glands
1. Pineal Gland• Produces melatonin
• regulates circadian rhythms
• Seasonal Affective disorder
2. Thyroid• Maintains metabolic activities
• Lack of thyronixe= mental
retardation in children
3. Pancreasreleases insulin and glucagon which
regulates blood sugar
Other Hormones /Glands
• 4. Gonads-
–Testis and Ovaries
–Release estrogen and
testosterone