Psych 330H Exam 1

Neurons

nerve cells that are the basic functional unit of the nervous system

synapses

junctions where neurons communicate with one another

axons

long fibers that transmit signals away from the neuron's cell body to other neurons or muscles

dendrites

branch-like structures that receive signals from other neurons and relay them to the cell body

Phineas Gage

injured left frontal lobe and prefrontal cortex, causing a change in his personality

frontal lobe is important for behavior and personality

functional localization (different brain areas contribute to different functions)

prefrontal cortex is connected with higher order behavior

perceptual illusions and psychophysics

perception is constructed:

• color blindness taught us about cones

• red, green, and blue cones (Maxwell)

• motion perception (rotating snakes illusion)

• impressionists made images feel alive (van Gogh)

• competition in the brain (stroop effect)

dissection and anatomy

physical organization of the nervous system:

• connection between brain and sensation

• physical connections are important for perception

• blood is circulated (important for survival; circle of willis)

• the brain is shockingly complex

golgi stain and microscopy

reveal individual neurons and their structure:

• the neuron doctrine (nervous system contains discrete cells that interact)

• we no longer believe the reticular theory (everything in the brain is a single net-like structure)

• visualizing a single cell in a dense forest of cells

electrical stimulation

functions can be evoked by activating brain tissue:

• muscles twitch when struck by an electrical spark; electrical patterns and signals from tissues like nerves and muscles (Luigi Galvani)

• changes in sodium and potassium conductance general electrical signals (squid experiment) (calcium stimulates movement)

behavioral experiments

systematic changes in behavior:

• Pavlov's dogs revealed how associations are learned

• unconditioned stimulus (food)

• unconditioned response (salivating)

• neutral stimulus (whistle)

• conditioned stimulus (bell after learning)

• conditioned response (salivating to bell)

• mice have empathy

electrophysiology/EEG

relationship of activity in the nervous system:

• orientation tuning of single neurons (primary visual cortex)

• electrical brain activity (electrodes measure the summed activity of many neurons) (timing)

MRI/fMRI

structure and activity in the living brain:

• reveals face-selective activity (million neurons)

• measures brain structure

• measure brain activity and function (location)

what is optogenetics

manipulate identified cells and circuits:

• reveals a hypothalamic circuit for aggression (locus in the brain)

correlation studies

measure the relationship between changes in brain or body measures and behaviors (ex: brain size to test scores)

somatic intervention

involves altering a structure or function within the brain or body to observe changes in behavior

• independent variable is factor being manipulated (ex: brain region or chemical)

• dependent variable is resulting behavior or change in response to manipulation

behavioral intervention

involves changing behavior to observe its effects on brain structure or function

• behavior is independent variable

• body's physical response or brain changes is dependent variable

neuroplastisity

the brain's capacity to change in response to environmental factors and experiences. this ability allows for learning and adaptation over time

levels of neuroscience analysis

spans various levels, from examining social interactions down to studying the structure of the underlying molecular mechanisms

neuron doctrine

• the brain and nervous system are made up of individual, discrete cells (neurons)

• each neuron is a distinct unit that receives, processes, and transmits information

• communication between neurons happens at synapses

• ramon y cajal

blood brain barrier

• wraps around blood vessels

• control what goes in/out cells

• selective transport of various nutrients, ions, organic anions, and macromolecules (glucose, water, amino acids) that are crucial to neural function

• allow nutrients in, keep toxins out

• selective permeability barrier separates circulating blood from CSF

• allows the passage of water, some gases, and lipid-soluble molecules by passive diffusion

• CNS

astrocytes

• maintain blood brain barrier

• physical structuring of the brain

• fuel neurons during periods of high energy use

• regulation of ion concentration in extracellular space

• modulation of synaptic transmission (forms bubble for communication)

• transmitter uptake and release

• neuron energy source

• star shaped

• CNS

microglia

• immune molecules (fight infection)

• scavenging: clean up foreign and damaged material

• phagocytosis: engulf cellular debris

• extracellular signaling: maintain homeostasis/inflammation and apoptosis

• antigen presentation

• cytotoxicity: immune protection

• synaptic remodeling during development and repair****

• CNS

oligodendrocytes

• myelin wraps axons

• myelination causes neural activity to hop rapidly between each node

• insulation: myelin insulates axons, preventing electrical impulses from dissipating

• increased speed of signal transmission: myelin allows for faster transmission of electrical signals by enabling Aps to jump (saltatory conduction)

• protection and support: myelin provides structural support to neurons and protexts axons from physical damage

• energy efficiency: myelination reduces the metabolic energy required for neurons to transmit signals by limiting the number of ion exchanges needed to propagate action potentials

• brain and spinal cord

• CNS

schwann cells

• 1 glia for 1 axon

• markers for axon regrowth after damage

• myelin

• PNS

input zone

• receives information from other cells via dendrites

• passive

integration zone

• Located in the cell body (soma), where incoming signals are combined

  and processed

  • energy active (conduction)

conduction zone

• The axon transmits electrical impulses away from the cell body

  • think of wires, rapid conduction

output zone

• Axon terminals communicate the neuron’s activity to other cells

multipolar neuron

• function: integrates many synaptic inputs and drives muscle

• relationship: many dendrites allow it to combine signals from many sources before sending one output to a muscle

• 1 long axon

• ex: spinal motor neuron

bipolar neuron

• function: relays visual information from photoreceptors to retinal ganglion cells

• relationship: simple input-to-output pathway that fits the layered organization of the retina

• 2 main extensions from the cell body; one dendrite receives info, 1 axon sends info onward

• ex: retinal cell

unipolar neuron

• function: conveys touch, pain, or temperature information from the body to the spinal cord

• relationship: one single fiber lets sensory signals travel rapidly from the periphery to the CNS with less interruption

• receptive pole and output pole

• ex: touch sensory neurons in the dorsal root ganglion with 1 branch carrying sensory info from the skin and the other carrying it into the spinal cord

presynaptic membrane

• located on the axon terminal of the sending neuron

postsynaptic membrane

• located on the dendrite or cell body of the receiving neuron

synaptic cleft

• the gap between the presynaptic and postsynaptic membranes

synaptic vesicles

• small spheres in the presynaptic axon terminals that contain neurotransmitters

why are glia essential for brain functions?

• myelination (speed and reliability of communication)

• immune response

• development (synapse refinement)

• cell signaling (glutamate homeostatsis)

stroke

• a medical condition caused by the rupture or blockage of blood vessels in the brain,

  leading to an insufficient blood supply

motor neurons

stimulates muscles or glands

sensory neurons

Respond to environmental stimuli, such as light, odor, or touch

interneurons

Act as relay/integration neurons, receiving input from other neurons and

sending signals to other neurons

axon hillock

The cone-shaped area of the cell body where the axon originates

axonal transport

The process of moving materials (such as proteins and organelles) along the

axon

nodes of ranvier

Gaps between sections of the myelin sheath that expose parts of the axon,

aiding in the rapid conduction of electrical signals

enteric nervous system

controls GI system

cranial nerves

Connect directly to the brain (sensory, motor, both)

• nerves (olfactory)

• optic (vision)

• vestibulocochlear (balance and hearing)

spinal nerves

Also called somatic nerves, they connect to the spinal cord

autonomic nervous system

Regulates glands and internal organs

telencephalon (cerebral hemispheres)

forebrain

• cerebral cortex

• limbic system

• basal ganglia

cerebral cortex

supports perception, thought, language, memory, voluntary action

• frontal lobe

• parietal lobe

• occipital lobe

• temporal lobe

limbic system

coordinates emotion, motivation, memory, behavior

cerebral cortex (neocortex)

he outermost layer of the cerebral hemispheres, characterized by

six distinct layers

• layer IV = input (sensory) (primary visual cortex)

• layer II/III = cortex talks to cortex (intercommunication) (association areas/cognition) (prefrontal association cortex)

• layer V = output to the body/subcortex (motor centers) (primary motor cortex)

limbic system

coordinates emotion, motivation, memory, behavior

basal ganglia

selects and refines actions, especially movement and learned behaviors

diencephlaon

forebrain

• thalamus

• hypothalamus

mesencephalon

midbrain

rhombencephalon

hindbrain

• metencephalon (cerebellum, pons)

• myelencephalon (medulla)

neuron at rest

maintains a balance of electrochemical forces, which allows it to be ready to transmit signals when needed

resting membrane potential

The electrical potential difference between the inside and outside of a neuron at rest is typically between –50 to –80 millivolts (mV), indicating that the interior of the neuron is more negatively charged compared to the outside

sodium-potassium pump

• 2 K+ into the cell (potassium gradient pushes out of the cells)

• 3 Na+ out of the cell (sodium gradient pushes in to the cells)

• net change in resting membrane potential = -1 in the cell (a little negative)

• uses a lot of ATP to maintain ion graidents (active transport)

symporter

• Ca2+ out

• Na+ in

• passive transport

• pump establishes it

• K+ and Na+ are the driving gradients for the symporters

• generating resting potential

leak channels

always open

• K+ channels are far more leaky

• diffusion gradient (stronger)

• K+ goes out

• Na+, Ca2+, Cl- go in

• more negative membrane potential

gated channels

can be controlled

• chemically (dendrites and soma)

• voltage (axon)

potassium equilibrium

Potassium ions (K+) move in and out of the neuron until the forces of diffusion and electrostatic pressure balance out, creating the resting membrane potential of around –60 mV

depolarization

A change in the membrane potential making the inside of the neuron less negative (closer to zero)

• more positive charge inside the cell

• excitatory

• more neural activity

hyperpolarization

A change in the membrane potential making the inside of the neuron even more negative relative to the outside

• inhibitory

• suppressing neural activity

action potential

A rapid and large change in the membrane potential that propagates along the axon, transmitting signals from one part of the neuron to another

• All-or-none principle: either occurs fully or not at all, regardless of

  stimulus strength

• Unidirectional Travel: travel in one direction along the axon due to the

  refractory state of the membrane after depolarization

• Increased Frequency with Stimulus Strength: Stronger stimuli result in more frequent

  , not larger ones

• Refractory Period: The time after when the neuron is less likely to fire

  again

• Absolute Refractory Period: No can be generated

• Relative Refractory Period: Only a very strong stimulus can trigger

regeneration of action potentials

regenerated along the axon as each adjacent section is depolarized, triggering a new action potential in the next section

spatial summation

The combination of multiple signals arriving from different locations on the neuron.

temporal summation

The combination of signals arriving at different times, but closely enough that their effects accumulate

postsynaptic potentials

Temporary changes in the membrane potential of the postsynaptic neuron, resulting from the action of neurotransmitters

excitatory postsynaptic potential (EPSP)

Causes local depolarization, pushing the cell closer to firing an action potential

inhibitory postsynaptic potential (IPSP)

Causes local hyperpolarization, making it less likely for the neuron to fire