Chapter 3 - Neuroscience & Behavior

psychology vs neurology

psychology studies thought and behavior
neurology studies the development and function of the nervous system

neurons

basic functional unit of the nervous system, generates electrical signals that allow them to transmit information

types of neurons

sensory, motor, interneuron

sensory neuron

A neuron that picks up stimuli from the internal or external environment and sends it to the CNS

interneuron

relay information to motor neurons, only in CNS

motor neuron

a neuron that sends an impulse to a muscle or gland, causing the muscle or gland to react

glia

cells in the nervous system that support neurons by cleaning out plaque and toxins in the brain during sleep

dendrite

branches off the cell body, receives incoming signals from other neurons

soma/cell body

contains nucleus

axon and axon terminal

send impulses away from the cell body to other neurons, glands, or muscles

myelin sheath

layer of fatty tissue encasing the axon, allows faster transmission of signals as the signal hops from node to node

two steps of sending a signal

1. along the cell (action potential)
2. between cells (neurotransmitters)

first step of sending a signal (along the cell)

A neuron before a signal is received will be at resting potential, meaning that the inside of the neuron will have a negative charge (around -70 mV) compared to the outside of the neuron. When a signal is received, the cell will begin to depolarize (lose charge) and once a threshold is reached (usually around -55 mV) the action potential is fired. This is an all or none response, so the neuron will fire at the same strength every time once the threshold is reached. After firing (action potential), the neuron will enter a refractory period where it cannot fire until it restores its resting potential.

multiple sclerosis (MS)

damage to the myelin sheath disrupts the signaling of the neuron - messages from the brain and spinal cord may be delayed and have trouble reaching their destination

symptoms of multiple sclerosis

stiffness, balance issues, muscle weakness

myasthenia gravis (MG)

antibodies destroy communication between nerves and muscles, causing weakness in skeletal muscles

what type of binding occurs in the synapse with neurotransmitters?

lock and key - specific neurotransmitters bind to specific receptors

what are the two types of signals?

excitatory and inhibitory

excitatory signals

neurotransmitters cause the postsynaptic cell to depolarize (increases likelihood of an action potential firing)

inhibitory signals

neurotransmitters cause the postsynaptic cell to hyperpolarize (decreases likelihood of an action potential firing)

what happens to neurotransmitters left in the synapse?

reuptake, enzyme deactivation, diffusion

reuptake of neurotransmitters

neurotransmitters are absorbed back into the presynaptic neuron

enzyme deactivation of neurotransmitters

enzymes destroy the neurotransmitters in the synapse

diffusion of neurotransmitters

neurotransmitters passively drift out of the synaptic gap

adrenaline

fight or flight neurotransmitter

noradrenaline

concentration neurotransmitter

dopamine

pleasure neurotransmitter

serotonin

mood neurotransmitter

GABA

calming neurotransmitter

acetylcholine

learning neurotransmitter

glutamate

memory neurotransmitter

endorphins

euphoria neurotransmitter

types of neurotransmitter mimics

agonists and antagonists (agonists mimic and antagonists oppose neurotransmitters)

agonists

mimics the action of a neurotransmitter to increase production or release of a neurotransmitter by blocking reuptake

antagonists

opposes the action of a neurotransmitter to decrease a neurotransmitter's action by blocking production or release of it

two major divisions of the nervous system

peripheral and central

two major divisions of the peripheral nervous system

autonomic (controls organs and glands) and somatic

two major divisions of the autonomic nervous system

sympathetic (fight or flight) and parasympathetic (rest and digest)

two major divisions of the somatic nervous system

sensory input and motor output (controls voluntary movement)

spinal cord

a highway for signals that sends the brain's commands and relays the body's messages

reflex arc

a direct connection between a sensory neuron and a motor neuron that allows a rapid response to a stimulus, often without conscious brain involvement (ie blinking)

cerebral cortex

the outermost layer of the brain responsible for our most complicated processes

frontal lobe

responsible for planning, judgement, memory, reasoning, abstract thinking, movement

prefrontal cortex

executive function (SOAP: sequencing, organization, abstraction, planning), emotional regulation, decision making

motor cortex

controls voluntary movements

parietal lobe

responsible for processing information about touch

somatosensory cortex

associated with the ability to perceive touch and pressure

area on the cortex

the more area on the cortex, the more sensitivity in the corresponding part of the body

occipital lobe

responsible for processing visual information

temporal lobe

responsible for processing auditory information

cerebrum

area of the brain responsible for all voluntary activities of the body

Wernicke's area

language comprehension

Broca's area

speech production

brain lateralization

specialization of function in each hemisphere

corpus callosum

a broad band of nerve fibers joining the two hemispheres of the brain

structure of the brain

hindbrain, midbrain, forebrain

hindbrain

responsible for basic functions

midbrain

coordinates movement and receives sensory information

structures of the hindbrain

medulla/oblongata, reticular formation, cerebellum, pons

medulla/oblongata

controls heart rate, circulation, and breathing

reticular formation

region of the pons that regulates levels of consciousness and arousal

cerebellum

controls motor coordination and balance

pons

bridge between cerebellum and brain that maintains circadian ryhthm

structures in the forebrain

cerebral cortex (divided into occipital, parietal, temporal, and frontal lobe), subcortical structures (thalamus, limbic system, pituitary gland)

limbic system

processes and manages emotions, behaviors, memories, autonomic nervous system, etc

parts of the limbic system

thalamus, hypothalamus, amygdala, hippocampus, pituitary gland

thalamus

sensory control center for all senses except smell, sends sensory information elsewhere

hypothalamus

maintains homeostasis, directs pituitary gland

amygdala

activated for strong emotional responses to stimuli

hippocampus

memory

pituitary gland

master gland of the endocrine hormonal system, directs other glands

contralateral

each hemisphere receives information from the opposite side of the body

transcranial magnetic stimulation (TMS)

the use of strong magnets to briefly interrupt normal brain activity/ deactivate part of the brain

endocrine system

set of glands that secrete chemical messengers (hormones) into the bloodstream

Urbach-Wiethe disease

a disease in which the amygdala and adjacent areas are calcified, leading to an inability to feel fear

brain plasticity/neuroplasticity

ability of the brain to modify itself or create new connections to allow for development or let the function of a damaged part of the brain transfer to a different part

examples of neuroplasticity

long term potentiation/LTP (pathways that are used more frequently become stronger) and neurogenesis (creation of new neurons)

lesioning

removal or destruction of part of the brain

lesion studies

examine how injuries to different parts of the brain impact function

neuroimaging

the use of various techniques to create pictures of the structure and function of the living brain

two types of neuroimaging

structural (CT/MRI) and functional (fMRI)

structural neuroimaging

provides pictures of soft tissue, shows tumors, lesions, etc

CT/CAT scan

a series of x-ray photographs taken from different angles and combined by computer into a composite representation of the brain

advantages of CT scans

fast, cost-effective

disadvantages of CT scans

some radiation, less precise visuals

MRI scan

uses radio waves and a very strong magnetic field to produce images of the soft tissue

advantages of MRI scans

very detailed, no exposure to radiation

disadvantages of MRI scans

longer, more expensive

fMRI/functional MRI

measures changes in oxygen levels through blood flow as brain areas activate and deactivate, showing brain activity

advantages of fMRI

maps brain activity

disadvantages of fMRI

longer, more expensive

EEG (not a brain scan)

records electrical patterns in the brain

advantages of EEG

portable, can be used on infants, accurate at recording fast changes in neural activity

disadvantages of EEG

100 pages of activity are evaluated, no image of the brain is produced