Neuroscience & Behavior

Neurons

Neurons

Basic functional units of the nervous system

Generate electrical signals called action potentials, which allow them to quickly transmit information over long distances

Glial cells (glia)

Maintain homeostasis, support, nourish and protect neurons by cleaning out plaque & toxins in the brain during sleep (waste management)

Cell body (soma)

The cell's life support center, contains nucleus

Axon hillock

Cone shaped region of an axon where it joins the cell body

Site of summation- controls the firing of the neuron. If the signal exceeds a certain threshold, the action potential will be triggered

Nodes of Ranvier

Gaps in the myelin sheath along the axons; they contain sodium and potassium ion channels, allowing the action potential to travel quickly down the axon by jumping from one node to the next

Dendrites

Receive messages from other cells

Axon

Passes messages away from the cell body to other neurons, muscles, or glands

Neural impulse

Electrical signal traveling down the axon

Myelin sheath

Covers the axon of some neurons and helps speed neural impulses

Terminal branches of axon

Form junctions with other cells

Terminal buttons

End of axon, filled with neurotransmitters that are sent across the synapse

Sensory (afferent) neurons

Neurons that carry incoming information from the sensory receptors to the brain and spinal cord

Interneurons

Only in the central nervous system (brain, spinal cord), relays information to motor neurons

Motor (efferent) neurons

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

Resting potential

Neuron at rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron (-70mV)

Action potential

Na+ in (depolarization) --> difference between inside and outside becomes positive --> K+ out (repolarization) --> hyperpolarization (extra negative) --> back to resting state

Refractory period

After a neuron fires. Neuron cannot fire because it is resetting itself to its original resting potential state.

Excitatory neurotransmitters

Cause the postsynaptic cell to depolarize, increasing the likelihood of an action potential (endorphins)

Inhibitory neurotransmitters

Cause the postsynaptic cell to hyperpolarize, decreasing the likelihood of an action potential (GABA)

Reuptake

Neurotransmitters are absorbed back into the presynaptic neuron

Acetylcholine (ACh)

Enables voluntary muscle control and memory

Deficit: Alzheimer's

Dopamine

Influences movement, attention/alertness, rewards/pleasure (related to addictions)

Excess: Schizophrenia

Deficit: Parkinson's disease

Serotonin

Mood regulation

Deficit: anxiety disorders like OCD, eating disorders

Epinephrine

"Fight or flight" response (increased heart rate, circulation, respiration)

Alertness/arousal

Norepinephrine

Slows down appetite and digestion during fight or flight

Excess: mania

GABA

Major inhibitory neurotransmitter - inhibits excitation/anxiety

Endorphins

Pain relief and feelings of pleasure, stress reduction, "natural opiates"

Glutamate

Major excitatory neurotransmitter; involved in memory, cognition, mood regulation

Agonist

A chemical that mimics the action of a neurotransmitter (excitatory)

Increases production/release of neurotransmitter or blocks reuptake in the synapse

Antagonist

A chemical that opposes the action of a neurotransmitter (inhibitory)

Decreases a neurotransmitter's action by blocking production or release

Hindbrain

Basic functions: includes the brain stem connects the brain to the spinal cord and coordinates many vital functions, such as breathing and heartbeat (pons, cerebellum, medulla)

Midbrain

Arousal, movement, orientation, motivation: Controls many important functions such as the visual and auditory systems as well as eye movement. Relay station for central nervous system (forebrain --> spinal cord)

Forebrain

Complex functions: cerebral cortex allows higher mental function, 4 lobes with association areas that interpret information registered from the cortex

Frontal lobe

Planning, judgment, memory, reasoning, abstract thinking, movement

Parietal lobe

Information about touch (sensory cortex)

Occipital lobe

Visual processing (visual cortex)

Temporal lobe

Hearing (auditory cortex) and language

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 is associated with the ability to perceive touch & pressure

Cerebellum

Movement, balance, fine motor skills, coordination

Brainstem

Top of spinal cord, consists of medulla and pons

Spinal cord

Consists of nerves that carry incoming and outgoing messages between the brain and the rest of the body

Broca's area

Production of speech (frontal lobe)

Wernicke's area

Comprehension of speech (temporal lobe)

Limbic system

Group of forebrain structures involved in motivation, emotion, learning, + memory

Amygdala: emotional memory- fear, aggression, strong emotional response

Hippocampus: formation of explicit memories

Hypothalamus: controls hormone release by pituitary gland, maintains homeostasis, hunger, thirst, temperature

Corpus callosum

Axon fibers connects two hemispheres

Thalamus

Relays sensory information to the cerebral cortex (except smell)

Pons

A brain structure that relays information from the cerebellum to the rest of the brain- sleep/wake cycle

Medulla

Automatic functions: breathing and heart rate

Reticular formation

Plays an important role in controlling arousal- mediating the overall level of consciousness (alertness/unconsciousness)

Prefrontal cortex

Part of frontal lobe responsible for executive function, emotional regulation, decision making - last part to develop

Divisions of the nervous system

Central and Peripheral

Somatic and Autonomic

Sympathetic and Parasympathetic

Peripheral nervous system

The sensory and motor neurons that connect the central nervous system to the rest of the body

Somatic nervous system

Transmits sensory information & controls voluntary movement, muscular reflex arc

Autonomic nervous system

Self-regulating involuntary and automatic body functions (blood flow, heartbeat, digestion, breathing)

Sympathetic = fight or flight (arousal) (alert & ready for action)

Parasympathetic = rest and digest (calming)

TMS (transcranial magnetic stimulation)

Short electromagnetic pulses are administered through a coil. Causes small electrical currents that stimulate nerve cells in the targeted brain region. Has been used study motor cortex or in extreme cases treat depression by stimulating nerve cells.

Brain lateralization

Inclination for certain cognitive processes (language, formulating memories, and body movement) to be specialized to one hemisphere of the brain

Ex: Broca's and Wernicke's area both on left hemisphere (language control)

Michael Gazzaniga

Split-brain research; understanding of functional lateralization in the brain; how the cerebral hemispheres communicate

Phineas Gage

Railroad worker who survived a severe brain injury to the frontal lobe that dramatically changed his personality and behavior; case played a role in the development of the understanding of the localization of brain function

Neuroimaging

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

Structural neuroimaging

Show anatomy--pictures of soft tissue. Reveals tumors, lesions, etc.

CT/CAT scan: fast and cost-effective but offers less precise visualization

MRI: very detailed and no exposure to radioactivity but longer and expensive

Functional neuroimaging

PET scan: shows where glucose is present (hot spots)

- Helpful to study cause of seizures but expensive and radioactive

fMRI: creates activation maps through increase of blood flow to show mental processes

- Maps brain activity but long and expensive

EEG

Non-invasive, records electrical patterns in the brain.

Helps diagnose conditions such as seizures, epilepsy, head injuries, dizziness, headaches, brain tumors and sleeping problems

Not an image/brain scan

Endocrine system

Networks of glands that produce & secrete hormones.

Gland --> Hormone Released Into Bloodstream --> Effect

Hormones offer a slower message than neurotransmitters but offer a longer-lasting impact

- Fight or flight response controlled by hypothalamus

- Sympathetic Nervous System stimulates the adrenal glands triggering adrenaline (epinephrine) and noradrenaline

Pituitary gland

Controlled by the hypothalamus, which tells your pituitary gland to start or stop making hormones