AP Psych Nervous System, Neurons, Neurotransmitters, Brain Plasticity and Scans

The Neuron

What is A?

Dendrites - receives incoming information

The Neuron

What is B?

Nucleus - don’t forget cell body/soma is what it is in

The Neuron

What is C?

Axon - carries neural impulse away from cell body

The Neuron

What is D?

Myelin Sheath - insulates axon and helps neural impulses travel faster

The Neuron

What is E?

The Nodes of Ranvier - allows the action potential to “jump” from node to node

The Neuron

What is F?

Axon terminals - releases neurotransmitters toward the next neuron the presynaptic ending

Synapse - the complete functional connection between two cells including axon terminal, synaptic cleft, and postsynaptic membrane

The synaptic gap/cleft is what neurons communicate through

Neural firing

Called an action potential - has an all-or-nothing response (neuron either fires or does not), dendrites receive neurotransmitter from another neuron across the synapse, reaches its threshold then fires based on all-or-nothing response

How do neurons communicate?

By electrical pulses and chemical signals, communicate through synapse

Acetylcholine (ACh)

Function in motor movement, learning and memory

Released when the nervous system needs to communicate with muscles or support certain brain functions

Example of ACh

ACh - move and remember

Deciding to shoot a basketball, the ACh helps send the message to move muscles and also plays a role in remembering how to shoot.

Excessive ACh

Muscle overactivity such as twitching or spasms

Lack of ACh

Linked to Alzheimer’s disease

Dopamine

Function in motor movement, attention, motivation, reward, emotion, and learning

Can be released when brain is processing rewarding/motivating experiences

Example of Dopamine

Smelling your favorite food and getting excited to eat it

Excessive Dopamine

Associated with psychosis/schizophrenia symptoms

Lack of Dopamine

Lack of movement problems; associated with Parkinson’s disease

Serotonin

Function in mood controls, sleep, hunger, and arousal

Neurons release it to help regulate these processes

Example of Serotonin

Your body is preparing for sleep at night

Excessive Serotonin

Contributes to serotonin syndrome - can cause agitation, confusion, etc.

Lack of Serotonin

Associated with depression and mood problems

Norepinephrine

Function in alertness and arousal

Helps the body and brain become alert and ready to respond, especially during important/stressful situations

Excessive Norepinephrine

Anxiety, increased alertness, and stress responses

Lack of Norepinephrine

Depressed mood, low energy, poor attention

GABA

Major inhibitory neurotransmitter

Released to reduce or slow neural activity when neurons need to be less active

Example of GABA

Trying to relax after a stressful day

Excessive GABA

Excessive slowing/sedation

Lack of GABA

Anxiety and seizures due to neurons becoming overly active

Glutamate

Major excitatory neurotransmitter

Important for learning, memory, and sending signals between neurons

Example of Glutamate

Learning a new concept for AP Psych

Excessive Glutamate

Overstimulation and damage to neurons

Lack of Glutamate

Interferes with learning and memory

Endorphines

Function in pain control and pleasure sensation

Helps reduce perception of pain and can contribute to feelings of pleasure/well-being

Released in response to things such as pain or strenuous activity

Example of Endorphins

Exercising and noticing discomfort seems less noticeable afterward

Excessive Endorphins

Stronger pain reduction

Lack of Endorphins

Increased sensitivity to pain

Agonist

Mimics neurotransmitter

Antagonist

Block neurotransmitter

CNS

Brain and spinal cord communicate through a series of electrochemical signals, process sensory information and direct the body’s responses

PNS

The nerves outside the CNS that carry sensory information to the CNS and relay motor commands out to the body

Sensory Neurons (Afferent Neurons)

Take information from the senses to the brain

Inter Neurons

Take messages from Sensory Neurons to other parts of the brain or to Motor Neurons

Motor Neurons (Efferent Neurons)

Take information from brain to the rest of the body

Somatic Neurons

Enable voluntary muscle movement through motor neurons, sensory neurons relay signals to the brain from sensory receptors (sent through CNS)

Autonomic Neurons

Uncontrollable (automatic functions of digesting, heart beating, etc.)

Sympathetic nervous system - arouses and expends energy (fight or flight)

Parasympathetic nervous system - slows heartbeat, lowers blood sugar, calms system afterwards

Endocrine System

Compromised of hormone-producing organs - have one of the largest impacts on long-term development, mood, and behavior

Major endocrine organs - thryoid, pancreas, adrenal glands, testes/ovaries, pituitary gland

Hormones

Chemicals created and released by organs that travel throughout bloodstream and impact feelings, perception, development, sexuality

Chemical receptors react to hormones based on how much of hormones are present signaling cellular growth, change, and brain activity

Thyroid

Located in neck, controls hormones that boost/reduce metabolism (consumption of energy)

Pancreas

Located in the abdomen behind stomach, releases insulin to manage glucose levels and energy use

Adrenal glands

Above kidneys, release adrenaline in fight or flight situations

Testes/ovaries

Releases testosterone and estrogen - sex hormones that impact sexual behavior, muscle, body fat, aggression

Pituitary gland

“Master gland”, regulates general hormone production, including growth hormone, sex hormones, etc.

Plasticity

Brain’s ability to change/adapt by developing new/alternative neural pathways from existing neurons

In some circumstances the brain can ______ neurons in response to damage by _____________________________________

reorganize, redirecting or training new neurons to maintain the path

Neural damage in the brain that causes the inhibition of limb use can be

reprogrammed to work properly after long-term use

Plasticity is ________ to neurons that have ___________ such as vision and audition, but not regions with entirely different purposes, such as frontal lobe neurons and sensory neurons

limited, similar functions

Neurogenesis

Process where the brain can slowly create small amounts of new neurons

When are neurons most plastic?

When we are young because they become more rigid and fixed as we age

ACh in the brain _______ the brain for _______, signaling to its neurnos that coming information must realign function

primes, change

One can do this by attempting to learn a new physical skill and repeatedly making mistakes

Repeated mistakes release large amount of ________; after 30 minutes a repeated failure opens the window for ______________

Acetylcholine (ACh), 60 minutes of plasticity - 60 min window is where you will perform desired behavior or skill to adapt

EEG

Electroencephalogram detects brain waves through their electrical output, used mainly in sleep research, looked at for function

CAT Scan

Computerized Axial Tomography 3d X-Ray of the brain, good for tumor locating, is used to look at structure

MRI

Magnetic Resonance Imaging a more detailed picture of brain using magnetic field to knock electrons off axis, takes many still pictures and turns images into a movie like production, looked at for structure

PET Scan

Positron Emission Tomography measures how much of a chemical the brain is using (usually glucose consumption), looked at for function

fMRI

Functional MRI, combination of PET and MRI, looked at for functional

Glial cells

cells in nervous system that support, nourish, and protect neurons, can also play a role in learning, thinking, and memory

Threshold

the level of stimulation required to trigger a neural impulse

Refractory Period

a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until axon returns to its resting state.

What is a neurotransmitter?

A chemical messenger that carries signals from one nerve cell to another

What is a receptor?

A protein on a cell that receives a specific neurotransmitter, it detects signals and triggers a response chemically

What happens when a neurotransmitter is released into the synapse

Molecules diffuse across the space to bind with specific receptors on the postsynaptic cell, altering its electrical state before being cleared from the synapse

Depressants

Slow down body functions

Stimulants

Arouse body functions

Hallucinogens

Distort perceptions or evoke sensation without sensory input

Alcohol, barbiturates, opiates (heroin and morphine)

Examples of depressants

Amphetamines (meth) and cocaine

Examples of stimulants

LSD (acid) and THC

Examples of hallucinogens

Neurotransmitters involved with heroin

Endorphins

What does heroin do to the neuron?

Mimics natural opiate receptor and turns off dopamine inhibition, dopamine is allowed to flood the synapse producing immediate feeling of sedation and well-being, it decreases the activity of the neurotransmitter

overall effect is it acts as a depressant, slowing the nervous system

Neurotransmitters involved with ecstasy

Serotonin

What does ecstasy do to the neuron?

Mimics serotonin and is taken up by serotonin transmitters, causes it to do its job backwards, excess serotonin gets trapped in synaptic cleft resulting in continuous binding, it increases neurotransmitter activity

overall effects serotonin pathways and responsibilities

Neurotransmitters involved with marijuana

GABA and Glutamate

What does marijuana do to the neuron

mimics anandamide and binds to cannabinoid receptors, inhibition turns off and dopamine is allowed to squirt into the synapse, allows GABA and glutamate to be released, takes longer to break down

overall effects short term memory, movement, speed, and calmness

Neurotransmitters involved with meth

dopamine

What does meth do to dopamine

meth mimics dopamine and enters dopamine vesicles, forcing dopamine molecules out and into synapse, excess dopamine is trapped and binds continuously, meth blocks recycling of dopamine, dopamine activity increases

overall effect meth is highly addictive as it works on the brain’s reward pathway

Neurotransmitters involved with alcohol

GABA - alcohol makes it more inhibitory, and Glutamate - alcohol prevents it from exciting cell

Alcohol causes ____ inhibitory activity

More

Neurotransmitters involved with cocaine

Dopamine

What does cocaine do to dopamine transporters?

Blocks transporters, causing dopamine to bind continuously, dopamine gets trapped in synaptic cleft, dopamine activity increases

overall effect is that cocaine concentrates on reward pathway

Neurotransmitters involved with LSD

Serotonin receptors, involved in perception and cognition

What does LSD do at serotonin receptors?

LSD binds to serotonin receptors, sometimes LSD inhibits receptors or LSD will excite receptors, alters brain signaling pathways

overall effects overactivity of serotonin, complex sensory effects, and altered perception

Which drugs affects dopamine

Meth and cocaine

Which drug affects GABA and glutamate

Alcohol

Which drug acts on serotonin receptors?

LSD

Which drug causes dopamine to remain in the synapse by interfering with dopamine transporters?

Cocaine

Which drug causes dopamine transporters to reverse their normal action

Meth

Opiates

Heroin and morphine - addiction comes fast, withdrawal symptoms bad