UNIT 2

glutamate

a major excitatory neurotransmitter involved in memory
oversupply can overestimate the brain, producing migraines or seizures (which is why people avoid MSG in food)

endorphins

natural, opiate-like neurotransmitters linked to pain control and pleasure
"morphine within"

why can't we take artificial opiates all the time if they lesson pain and boost mood, like our natural endorphins do for us?

the brain may stop producing its own natural opiates
when the drug is withdrawn, the brain then may be deprived of any form of opiate, causing intense discomfort

excitatory signals

GO

inhibitory signals

STOP

neuron

a nerve cell
basic building block of the nervous system
contains cell body and branching fibers

soma

cell body

dendrites

a neuron's bushy, branching extensions that receive messages and conduct impulses toward the cell body

axon

the neuron extension that passes messages through its branches to other neurons or to muscles or glands
terminal branches of axon form junctions with other cells

"dendrites listen, axon speak"

dendrites receive messages, and axon (terminals) sends/passes the message

myelin sheath

a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next
insulation
lack of myelin sheath causes multiple sclerosis (MS)

action potential

a neural impulse; a brief electrical charge that travels down an axon
response to stimulation by signals from our senses or when triggered by chemical signals from neighboring neurons
when excitatory signals exceed the number of inhibitory signals

how does a neuron firing allow axons to be compared to a line of falling dominoes?

when a neuron fires, the first section of the axon opens its gates, and positively charged ions flood through the cell membrane, which depolarizes that axon section, causing another axon channel to open, and then another, etc. like falling dominoes

refractory period

a period of inactivity after a neuron has fired
neuron pumps positively charged sodium ions back outside to fire again

threshold

the level of stimulation required to trigger a neural impulse

all-or-none response

a neuron's reaction of either firing (with a full-strength response) or not firing at all

synapse

the 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/cleft
less than 1 millionth of an inch wide

neurotransmitters

chemical messages that cross the synaptic gaps between neurons
binds to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse

reuptake

a neurotransmitter's reabsorption by the sending neuron

reuptake inhibitors

block neurotransmitters from returning to the sending neuron

acetylcholine (ACh)

enables muscle action, learning, and memory
- with Alzheimer's, ACh-producing neurons deteriorate

dopamine

influences movement, learning, attention, and emotion
- oversupply linked to schizophrenia
- undersupply linked to tremors and decreased mobility in PD

serotonin

affects mood, hunger, sleep, and arousal
- undersupply linked to depression
- some antidepressant drugs raise serotonin levels

norepinephrine

helps control alertness and arousal
undersupply can depress mood

GABA (gamma-aminobutyric acid)

a major inhibitory neurotransmitter
undersupply linked to seizures, tremors, and insomnia

agonist

a molecule that, by binding to a receptor site, stimulates a response
mimics neurotransmitters
ex. some opiate drugs produce a temporary 'high' by amplifying normal sensations of arousal or pleasure

antagonists

a molecule that, by binding to a receptor site, inhibits or blocks a response
ex. Botulin, a poison that can form in improperly canned food, causes paralysis by blocking ACh release

Franz Gall

one of the first people that tried to figure out the locations of the brain and where those biological processes/functions occurred

phrenology

studying bumps on the skull
could reveal a person's mental abilities and character traits

localization of function

the idea that various brain regions have particular functions

nervous system

body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems

sensory neurons (afferent neurons)

neurons that carry incoming information from the sensory receptors to the brain and spinal cord for processing

motor neurons (efferent neurons)

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

interneurons

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs

peripheral nervous system

sensory and motor neurons that connect the CNS to the rest of the body
gathers information

autonomic NS

part of PNS that controls the glands and muscles of internal organs
may be consciously overridden, but usually operates on its own

somatic NS

division of PNS that controls the body's skeletal muscles
"skeletal nervous system"s

sympathetic NS

arouses and expends energy in stressful situations

parasympathetic N

calms body and conserves energy
works with sympathetic NS to keep us in a steady internal state

central nervous system

brain and spinal cord

nerves

bundled axons that form neural 'cables' connecting the CNS with muscles, glands, and sense organs

what are neural 'networks' in our brain?

work groups of neurons that cluster
allows short, fast connections

what is the purpose of our spinal cord?

connects the PNS and the brain
governs our reflexes

simple reflex

spinal cord has the ability to affect reflexes without involvement of the brain

endocrine system

the body's 'slow' chemical communication system
set of glands that secrete hormones into the bloodstream
main purpose: to allow for communication

reflexes

simple, automatic response to a sensory stimulus
ex. knee-jerk response

hormones

chemical messengers that are manufactured by the endocrine glands
travel through the bloodstream and affect other tissues

adrenal glands

pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress
inner part helps trigger fight/flight response

pituitary gland

most influential endocrine gland
under the influence of the hypothalamus, the pituitary gland regulates growth and controls other endocrine glands
pea-sized structure located in the brain, next to the hypothalamus

hypothalamus

important link in command chain that governs bodily maintenance
some neural clusters in hypothalamus regulate thirst, body temp, and sex drive
tunes into blood chemistry and any incoming orders from other brain parts as it monitors the state of your body - controls pituitary gland

thyroid gland

affects metabolism

testis

secretes male sex hormones

parathyroids

help regulate the level of calcium in the blood

pancreas

regulates level of sugar in blood

ovary

secretes female sex hormones

neural network communication

the more connections you make between information, the better you will remember
the more you use information, the stronger the connections become

lesion

tissue destruction
naturally or experimentally caused destruction of brain tissue

EEG (electroencephalogram)

an amplified recording of the waves of electrical activity sweeping across the brain's surface
waves measured by electrodes placed on the scalp

CT scan (computed tomography scan)

a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice of the brain's structure
can reveal brain damage

PET scan (positron emission tomography)

a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task
detects 'hot spots' of cellular activity

MR (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue
shows brain anatomy

fMRI (functional magnetic resonance imaging)

a technique for revealing blood flow, and, therefore brain activity by comparing successive MRI scans
shows brain function and structure

brainstem

oldest part and central core of the brain
begins where spinal cord swells as it enters the skull
responsible for automatic survival functions
crossover point where most nerves to/from each side of the brain connect with the body's opposite side

medulla

base of brainstem
controls heartbeat and breathing

pons

sits just above the medulla
helps coordinate movements

thalamus

brain's sensory control center
located on top of brainstem
directs messages to sensory receiving axons in cortex and transmits replies to cerebellum and medulla

reticular formation

nerve network that travels through the brainstem and thalamus and plays an important role in controlling arousal

cerebellum

“little brain" at the rear of brainstem
functions include: processing sensory input, coordinating movement output/balance, and enabling nonverbal learning/money

nucleus accumbens

reward center

amygdala

two lima-bean-sized neural clusters in the limbic system
linked to emotion (aggression, fear)

Phineas Gage

American railroad foreman known for having survived a traumatic brain injury caused by an iron rod that shot through his skull and obliterated the greater part of the left frontal lobe of his brain. He became a man of bad and rude ways, disrespectful to colleagues, and unable to accept advice.

• extreme case that taught us more about frontal cortex and personality

hippocampus

processes conscious memories
converts short-term memories and into long-term memories
4 Fs: fight, flight, food, sexual functioning
reward/pleasure center

limbic system

neural system located below the cerebral hemisphere, associated with emotions and drives

cerebral cortex

the intricate fabric of interconnected neural cells covering the cerebral hemispheres
the body's ultimate control and information-processing center
"brain's thinking crown"

cerebrum

largest division of the brain, divided into 2 hemisphere, each divided into 4 lobes

• occipital

• frontal

• temporal

• parietal

the larger cortex of mammals offers increase capabilities for learning and thinking, enabling them to be more adaptable

!!!

glial cells

cells in the nervous system that support, nourish, and protect neurons
may play a role in learning and thinking
"glue cells"
makes up cerebral cortex

frontal lobes

behind forehead
involved in speaking and muscle movements and in making plans and judgments

prefrontal cortex

judgment, planning, processing of new memories

parietal lobes

top of head and toward the rear
receives sensory input for touch and body position

occipital lobes

back of head
includes areas that receive information from the visual fields

temporal lobes

above ears
includes auditory areas, each receiving information primarily from the opposite ear

motor cortex

area at the rear of the frontal lobes that controls voluntary movements
sends messages out to the body

why do some body parts get a larger portion of our brain's cortex devoted to them than others?

the brain devotes more tissues to sensitive areas and to areas requiring precise control (fingers, mouth > upper arm)

somatosensory cortex

area at the front of the parietal lobes that registers and processes body touch and movement sensations
receives sensory input

association areas

areas of the cerebral cortex that are not involved in primary motor or sensory functions - rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking

more complex animals have increased association areas of the cortex, which are responsible for interpreting, integrating, and acting on sensory information and linking it with stored memories

!!!

Broca's area

area of brain dedicated to speaking

Wernicke's area

area of brain dedicated to understanding

plasticity

the brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience
ability to modify itself after damage

neurogenesis

the formation of new neurons
usually in attempts for the brain to mend itself

lateralization

our brain's look-alike

left and right hemispheres serve different functions

corpus callosum

the large band of neural (axon) fibers connecting the two brain hemispheres and carrying messages between them

split brain

a condition resulting from surgery that isolates the brain's two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them

left brain

controls language processing and speech
contains Broca's (speech) and Wernicke's (understanding) areas

right brain

excels in making inferences
helps us modulate our speech
helps orchestrate our sense of self

consciousness

our awareness of ourselves and our environment
aware, explicit, deliberate

cognitive neuroscience

the interdisciplinary study of the brain activity linked with cognition (includes perception, thinking, memory, and language)
science concerned with study of biological processes and seeing where consciousness comes into play with these processes

dual processing

the principle that information is often simultaneously processed on separate conscious and unconscious traces

unconscious/subconscious

unaware, implicit, automatic