AP Psychology- Biological Bases of Behavior

unit 2

Franz Gall

Franz Gall

In 1800, Franz Gall suggested that bumps of the skull represented mental abilities; his theory, though incorrect, nevertheless proposed that different mental abilities were modular

Biological psychology

Branch of psychology concerned with the links between biology and behvaior; Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists

Neural communication

Neurobiologists and other investigators understand that humans and animals operate similarly when processing information

Similarities in the brain regions are all engaged in information processing

Neurons

the messengers;About 100 billion neurons (nerve cells) in the human brain;

Neurons have many of the same features as other cells: Nucleus, Cytoplasm,

Cell membrane;

What makes neurons unique is their shape and function

Neuron Structure

cell body (the cell's life support center); dendrites (receive messages from other cells); axon (passes messages away from the cell body to other neurons, muscles, or glands); myelin sheath (covers the axon of some neurons and helps speed neural impulses, covered w/ a fatty substance); terminal branches of axon/ terminal buttons (form junctions with other cells); neural impulse (electrical signal traveling down the axon)

Glial Cells

cells that insulate and support neurons

create the myelin sheath

remove waste products

provide nourishment

prevent harmful substances from entering the brain

types: astrocytes provide nutrition to neurons

Oligodendrocytes and Schwann cells insulate neurons as myelin

Schwann cells

A Schwann cell is a type of glial cell found in the peripheral nervous system

responsible for producing the myelin sheath

Schwann cells also play a role in nerve regeneration and support the overall health and function of neurons

Types of Neuroglia

polarized membrane

a lipid membrane that has a positive electrical charge on one side and a negative charge on another side, which produces the resting potential in living cells

Depolarization

the process that carries the neural impulse through the axon, action potential is what must happen for the process to occur

Sodium Potassium pump

pumps Na+ ions out from the inside of the neuron, making them ready for another action potential; K+ ions remain inside the axon

resting potential/resting state

Neuron is not transmitting information- it is resting

Membrane Potential over time

Resting potential/state

The resting potential of a neuron is the value its membrane potential keeps as long as it is not receiving stimulation or undergoing an action potential

action potential

An action potential occurs when a neuron transmits an electrical charge down its axon, which terminates in the release of chemical signals in the form of neurotransmitters; a brief electrical charge that travels down an axon, caused by the movement of positively charged ions in and out of the membrane

synapse

a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron; this tiny gap is called the synaptic gap or cleft

neurotransmitters

small chemicals released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential, this is how neurons communicate

reuptake

neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of re-uptake; this process applies the breaks on neurotransmitter response

all-or-none response

when the depolarizing current exceeds the firing threshold/absolute threshold, a neuron will fire; if the depolarizing current fails to exceed the threshold, a neuron will not fire

intensity of an action potential remains the same throughout the length of the axon

firing threshold/absolute threshold

the level of depolarization at which a neuron fires

refractory period

after a neuron fires an action potential, it pauses for a short period to recharge itself to fire again

neurotransmitter release

1. action potential causes vesicle to open

2. neurotransmitter released into the synapse

3. locks onto the receptor molecule in postsynaptic membrane

4. neurotransmitter reuptake in vesicles

Lock and Key Machanism

neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism; neurotransmitters fit like chemical keys in chemical lock

excitatory neurotransmitters

-the key fits and ‘opens’ the receiving neuron

-activation of the receptor causes depolarization of the membrane and promotes an action potential in the receiving neuron

inhibitory neurotransmitters

-the key fits in but only stops and other keys

-activation of the receptor causes hyperpolarization and depresses the generation of action potential

acetylcholine

-excitatory

-function: motor movement (causes muscles to contract) and memory

-lack of acetylcholine: Alzheimer’s, paralysis

dopamine

-both excitatory and inhibitory

-function: motor movement, alertness, & pleasure

-lack of dopamine: Parkinson’s disease

-too much dopamine: schizophrenia

GABA

-the most common inhibitory neurotransmitters in the brain

-functions: controls a wide variety of functions

-lack of GABA: Huntington’s disease, anxiety, epilepsy, insomnia

Glutamate

-the most common excitatory neurotransmitter in the brain

-function: memory

-too much glutamate: ALS (Lou Gehrig’s Disease), migraines, seizures

endorphins

-inhibitory

-function: alleviating pain

-structurally very similar to opioids (opium, morphine, heroine, etc.)

-we’ve become addicted to endorphin-caused feelings

-lack of endorphins: chronic pain disorders

Serotonin

-inhibitory in pain pathways

-functions: sleep, mood, appetite, and sensory perception (“mood and food”)

-lack of serotonin: depression

-too much: anxiety, limits dreaming

substance p

-excitatory

-P stands for pain

-responsible for the sending of pain messages throughout our body

Norepinephrine (AKA Noradrenaline)

-excitatory

-functions: controls alertness and arousal, also functions as a hormone

-lack of Norepinephrine: can lead to depressed moods

neurotransmissions and drugs

-Drugs can affect synapses at a variety of sites and in a variety of ways

-drugs mimic NT

-increasing the number of synapses/firing

-release of NT from neurons with or without synapses/firing

-produce more/less NT than what is normal

-prevent vesicles from releasing NT

-block reuptake of NT into sending neuron

agonists

-agonists excite & mimic neurotransmitters

-structurally similar to neurotransmitters and mimics its effects on the receiving neuron

-ex) Morphine mimics the action of endorphins by stimulating receptors in brain areas involved in mood and pain sensations

antagonists

-antagonists inhibit & bloc neurotransmitters

-structure similar enough to neurotransmitter and occupies its receptor site and blocks it’s action, but not similar enough to stimulate the receptor

-curare poisoning paralyzes its victims by blocking ACh receptors involved in muscle movement

tolerance

builds with repeated use, requires increasing amount

physical dependence

intense cravings and physiological need

withdraw

painful side effects from stopping after long term usage

depressants

-alchohol (stimulates GABA)

-Barbiturates (tranquilizers)

-Benzodiazepines (anti-anxiety)

-opiates

opiates

-opium, morphine, oxycodone, heroine

-suppress pain, induce sleep, induce state of euphoria

-antagonist for endorphins; highly addictive

-leads brain to stop producing own endorphins

Hallucinogens

-LSD, mushrooms, peyote

-alter perception and create dramatic hallucinations

-disrupts transmissions of serotonin

-THC is also a hallucinogen (in marijuana)

Stimulants

-nicotine, caffeine

-MDMA- affects serotonin
-Cocaine and Amphetamines; increase dopamine and norepinephrine activities, elevated mood and energy; can lead to long-lasting damage to dopamine neurons

Reuptake Inhibitors

SSRIs: selective serotonin reuptake inhibitor

can be done with other neurotransmitters as well

Mirror Neurons

neurons that fire when you do an action, or you watch someone do an action; neural basis of ‘observational learning’ & empathy

nerves

-neural cables containing many axons

-part of the peripheral nervous system

-connect the central nervous system with muscles, glands, and sense organs

sensory (afferent neurons)

INPUT from sensory organs to the brain and spinal cord

sensory vs motor neurons mnemonic- SAME

Motor (efferent) neurons

OUTPUT from the brain and spinal cord, to the muscles and glands

sensory vs motor neurons mnemonic- SAME

effector cells

respond to stimulus at the terminal end of neuron

interneurons

carry information between other neurons only found in the brain and spinal cord

autonomic nervous system

-”involuntary”

-regulates the function of our internal organs, such as the heart, stomach, lungs, intestines

-part of the peripheral nervous system and it also controls some of the muscles within the body

-regulates involuntarily responses

ex.) we do not notice when blood vessels change size or when our heart beats faster

somatic nervous system

-”voluntary”

-regulates voluntary movements

-part of the peripheral nervous system, connects the brain to the motor neurons such as those found in the skeletal muscles

-we are in control of this system (voluntary) and we use it when we want to make our muscles move

autonomic nervous system

sympathetic vs parasympathetic

sympathetic nervous system

-”arouses”

-prepares the body for "fight or flight" responses

-It activates during times of stress or danger, increasing heart rate, dilating pupils, and releasing adrenaline

-It also inhibits non-essential functions like digestion

parasympathetic nervous system

-”calms”

-helps regulate the body's rest and digest

-responsible for conserving energy, promoting digestion, and promoting relaxation

-works in opposition to the sympathetic nervous system

central nervous sytem

the brian and spinal cord

brain

part of the CNS that plays important roles in sensation, movement, and information processing

spinal cord & spinal cord reflexes

-plays a role in body reflexes and in communication between the brain and the peripheral nervous system

-simple reflexes are controlled by interneurons in your spinal cord

endocrine system

-body’s “slow” chemical communication system

-communication is carried out by your hormones in your blood that is synthesized by a set of glands

hormones affect on behvaior

-growth of bodily structures such as muscles and bones, differences between males and females

-metabolism

-energy levels

-preparing the body for stressful situations

-mood

pituitary gland- “master gland”

-secretes many different hormones, some of which affect other glands

-controlled by the hypothalamus

-secretes hormones which control the output of hormones by other endocrine glands

-monitors hormone levels to prevent imbalances

-Human growth hormone (HGH): growth

-oxytocin: boding (released frequently by touch)

-cortisol: stress hormone

-norepinephrine is also a hormone released by adrenal glands

thyroid gland

affects metabolism, among other things

imbalance in thyroid can affect mood, weight

parathyroids

help regulate the level of calcium in the blood

Adrenal glands

-inner part, called the medulla, helps trigger the “fight or flight” response

-releases adrenaline

pancreas

regulates the level of sugar in the blood

ovary

secretes female sex hormones

testis

secretes male sex hormones

Brain lesion

Experimentally destroys brain tissue to study animal behaviors after such destruction

Autopsy

post mortem study of a brain to compare brain changes with behavior

Clinical observation

-shed light on a number of brain disorders

-alterations in brain morphology due to neurological and psychiatric diseases are now being catalogued

Electroencephalogram (EEG)

An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp

CT (computed tomography scan)

A series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body; also called CAT scan

PET (positron emission tomography) scan

A visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

MRI (magnetic resonance imaging)

Uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue; top images show ventricular enlargement in a schizophrenic patient; bottom image shows brain regions when a participant lies

fMRI (functional magnetic resonance imaging)

Can reveal brain functioning and structure by examining changes in blood flow based on different activities

brainstem

-Oldest part of the brain

-beginning where the spinal cord swells and enters the skull

-responsible for automatic survival functions

-medulla: basic life functioning and reflexes

-pons: sleep/wake cycle

Hindbrain

-brain stem

-reticular formation

-cerebellum

-thalamus

Reticular formation

Alertness/attention to incoming stimuli

cerebellum

Balance, voluntary movement, procedural learning

Thalamus

Sensory relay station except smell

The limbic system

-a doughnut-shaped system of neural structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and drives for food and sex

-includes hippocampus, amygdala, and hypothalamus

Amygdala

Consists of two almond-shaped neural clusters linked to the emotion of fear and agression

Hypothalamus

-lies below (hypo) the thalamus

-controls 4 f’s (fight, flight, feeding, and fornicating)

-body temperature

-circadian rhythms

-helps govern the endocrine system via the pituitary gland (brain region controlling the pituitary gland)

-hypothalamic centers are ventromedial and lateral

Ventromedial hypothalamus (VMH)

suppresses hunger (stimulation)

Lateral hypothalamus

increases hunger

hypothalamus & hormones

orexin increase- hypothalamus-increases hunger

ghrelin increase- stomach- increases hunger

insulin increase-pancreas-increases hunger

leptin increase-fat cells-decreases hunger

PPY increase-digestive tract-decreases hunger

Hippocampus

-structure that contributes to the formation of memories

-damage to the hippocampus has been implicated in the memory loss associated with Alzheimer’s

-case studies

frontal lobes

decision making, planning, movement

parietal lobes

include the somatosensory cortex (touch); spatial processing (location)

occipital lobes

include the visual areas which receive visual information from the opposite visual field

temporal lobes

auditory processing, facial and object recognition, olfactory cortex

motor cortex

area at the rear of the frontal lobes that controls voluntary movements

somatosensory cortex

area at the front of the parietal lobes that registers and processes body sensations, sense of touch, temperature, and pain

motor vs sensory cortex brain controls

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

-Phineas Gage

-more intelligent animals have increased “uncommitted” or association areas of the cortex

language

-aphasia: an impairment of language, usually caused by left hemisphere damage to Broca’s area (impaired speaking) or to Wernicke’s area (impaired understanding)

broca’s area

controls speech muscles via the motor cortex

wernicke’s area

interprets auditory code

the homunculus

representation of how large body parts would be if they were to scale of how much the brain controls

plasticity

the brain’s ability to modify itself after some type of injury or illness