PSC Ch. 3

branching extensions that detect information from neighboring neurons

extended projection from the cell body that transmits information from cell body to terminal buttons

point of release for chemical signals being sent from the neuron into the synapse

Point of chemical communication between neurons

Small gap between two neurons

"sender"

"receiver"

fatty lining around axons

increases speed of information transmission down an axon

small gaps between sections of myelin where action potentials are transmitted

Neural impulse sent down an axon that results in the release of chemicals from the terminal buttons

• Resting potential
• Action potential
•      1. Sodium channels open
•     2. Potassium channels open
•     3. Sodium channels close
•     4. Potassium channels close
•     5. Hyperpolarization
• Resting potential

Refractory period – neuron cannot fire

• Neuron is polarized
•      
•       Slightly more negatively charged inside the neuron than outside

Chemicals released from the terminal button of the presynaptic neuron to signal the postsynaptic neuron

increase action of the postsynaptic neuron

decrease action of the postsynaptic neuron

1. Neurotransmitter production in the axon

2. Once produced, neurotransmitter is stored in vesicles

3. Vesicles attach to presynaptic membrane

They open and release stored neurotransmitters into the synaptic cleft 

Result of action potential

4. Neurotransmitter binds to receptors on postsynaptic membrane

• 5. Unbound neurotransmitter activity is stopped by one of 3 methods 
•   1.)Reuptake    
•     2.)Deactivation     
•       3.) Autoreception

• After release from the vesicles at the terminal button
•    
• any neurotransmitter that does not bind to a postsynaptic receptor
•  
• is taken back up by the presynaptic terminal button

After release from the vesicles at the terminal button

any neurotransmitter that does not bind to a postsynaptic receptor

is broken down in the synapse by specific enzymes

Released neurotransmitters bind to receptors on the presynaptic neuron

Motor control of muscles

Learning and memory

Paralysis – botulism blocks ACh release, inhibits muscle movement

• Violent muscle contractions – black widow spider venom
• causes a flood of ACh to be released, causing too much muscle contraction

Over-release leads to ACh depletion, paralysis

Temporary amnesia – occurs if ACh release is blocked

Motor control of voluntary movement

Reward and motivation

Movement difficulties

Parkinson’s – too little DA production

Schizophrenic-like symptoms – too much DA production

• Mood
• Hunger
• Sleep and attentiveness

Depression – an underproduction of 5-HT is related to depressive disorders

Alertness and vigilance

Depressive mood – underproduction of NE can depress moods

Primary inhibitory neurotransmitter

Seizures – potentially linked to underproduction of GABA

Tremors – underproduction decreases muscle control

Primary excitatory neurotransmitter

Migraines – potentially linked to overproduction of Glu

 Seizures – potentially linked to overproduction of Glu

Includes the medulla, pons & midbrain

•  Important for regulating basic functions
•      Heart rate
•         Respiration
•             Vomiting

Coordinated movement & balance

Contains lobes similar to the cortex

      Each control different functions related to motor behavior

• Hypothalamus
• Thalamus
• Hippocampus
• Amygdala
•  Basal ganglia
• Nucleus accumbens

Major regulatory structure

• Motivated behaviors
•     Thirst
•     hunger
•     Aggression
•     Sexual behavior

Endocrine system control

Relay center for sensory information

Except olfaction!

Memory formation

May be subject to plasticity (the brain's natural ability to change)

Emotional association learning

Fear response

Planned movement production

 DA production here controls fluid movement

Reward

Motivating behavior

 DA neurons here are activated during pleasurable experiences

Outermost layer of the brain

Responsible for sensory integration, thought production complex behavior

4 lobes

Higher-order processing & planning

Movement

Conceptualizing spatial layouts

Touch sensation

Memory

 Auditory information processing

Specialized visual processing area

Visual information processing

Activation prepares the body for some required action

Non-vital systems deactivated

Fight-or-flight response

Activation returns the body to a resting state

Maintains homeostasis

Neurotransmitters

Released from terminal buttons

Travel short distances

Act very quickly

Hormones  

Released from endocrine glands

Travel throughout the body

Slow-acting

its chemicals released into the bloodstream from endocrine glands that act on a target tissue

Hormones bind to receptors on the target tissue and influence its actions

Produces hormones in response to a wide range of stimuli

• Feeding
• stress
• social behavior
• sexual behavior
• physical growth

Release point for hormones from CNS to periphery

• oxytoxin- uterine contractions
•              mother&infants bond
•              romantic relationship

• Vasopressin – water balance
•                    social bonds
•                    chronic stress regulation

Thyroid hormones

 Metabolism rates

Glucocorticoids (hormone)

increase blood sugar level

speed up break down of proteins

have anti-inflammatory effects

epinephrine & norepinephrine

fight or flight response

insulin

regulates glucose levels

• androgens (testes)
• estrogens (ovaries)

Development of reproductive organs (prenatal)

Secondary sex characteristics

Adult sexual behavior

the genetic make-up of an organism

determined at fertilization

observable characteristics

due to genotype and the environment

Gene is expressed if it is present

Gene is expressed only if it is present with another recessive gene

• Critical period 
•      Plasticity occurs only inside a defined developmental period.
• Experiences outside this period do not result in plasticity.

A trait is determined by multiple genes, as well as by environmental influences

intentional cell death

may be pruning of unused neural networks to make brain work efficiently