PSY-P 346 Exam Study Guide

Trepanation - what is remarkable about prehistoric skulls

Holes being burred on top of skulls

Emphasis on heart instead of brain in ancient time

Heart was seen as source of soul/memory; located centrally, life stopped when your heart stops beating

Hippocrates

Father of modern medicine

Hippocrates’s beliefs about the brain

The belief that brain was source of sensation and intelligence

Aristotle’s belief about the brain

The belief that the brain was the radiator (cooling function)

Galen

Physician to gladiators and follower of Hippocrates

Galen’s belief of brain

The belief that cerebrum imprints memories and cerebellum controls muscles

Fluids Hypothesis

The hypothesis based on the idea that the brain has fluid filled cavities and all neuronal transduction is done by movement of fluid

Dualism - Descartes

The belief that the mind and body are separate entities - who believed this

Pineal gland

The brain structure which is most important for dualism

Galvani and discovery about frog leg muscles - Benjamin Franklin as inspiration

The hypothesis that replaced the fluids hypothesis - founded that frog leg muscles twitch when attached to wire during thunderstorms - who founded it and who inspired him

Phrenology

The idea that there were specialized areas of the brain that caused the surface of the brain to be different - not supported today (e.g. if you’re really funny, the spot in your brain for humor would be enlarged)

Localization

The idea that the brain has specialized parts

Gall’s influence on localization

Gall’s foundings from phrenology

Broca’s influence on localization

What the discovery of Broca’s area from a case study where a lesion in the left frontal lobe caused a man be unable to speak led to

Cajal’s theory on network neurons

The idea that neurons are discrete, independent cells

Golgi’s theory on network neurons

The idea that neurons are a continuous network

Molecular neuroscience

studying what the roles of molecules in brain function is

Cellular neuroscience

Studying how nerve cells operate and how they transmit information

Systems neuroscience

Studying how visual systems represent our surroundings, how motor systems keep us in balance, etc

Behavioral neuroscience

Studying what makes us alert/sleepy, effects of drugs on behavior, etc

Cognitive neuroscience

Studying what happens in the brain when we remember something

Neurons

Cells specialized for communication

Glia

cells that insulate, support, and nourish neurons

Nissl stain pros

Stains nuclei as well as Nissl bodies (rough ER); allows visualization of how neurons are arranged

Cons of Nissl stain

Only shows cell bodies, not axons or dendrites

Golgi stain pros

Provides a more complete visual of a neuron

Golgi stain cons

Only stains a small percentage of neurons - made it difficult to tell if they were all connected or not

Reticular theory - Golgi

The idea that nerve cells form a continuous network - who discovered it

Neuron doctrine - Cajal

The idea that nerve cells are discrete, independent cells - who discovered it - the winner of the battle between Cajal and Golgi

Soma

cell body

Neurites

thin tubes extended from soma

Dendrites

Receives synaptic inputs from other cells

Axon

sends nerve impulses away from soma

Ribosomes

site of protein synthesis

Smooth Endoplasmic Reticulum

Processes protein folding and Calcium regulation

Golgi apparatus

Site of ‘post-translation’ modifications

Astrocytes - Glial cell

Regulates chemical content in space around neurons + removes excess neurotransmitters

Myelinating glia, Oligodendrocytes, Schwann Cells

Insulates axons to improve efficiency of signal transfer

Synapse

Where neurons come into contact with one another

Bipolar cell

A cell body + two neurites (dendrite + axon)

Multipolar cell

Cell body + several neurites

Alzheimer’s Disease

What happens when tau clumps together to form tangles and disruptes the microtubules

Multiple Scelrosis

The disease linked to the breakdown of myelin

Salty fluids + Lipids + Proteins

Ingredients of a membrane

Salty Fluids

What must be both inside and outside of cell, made up of water and ions

Cations - sodium, potassium, calcium

Positively charged ions

Anions - Chlorine

Ions that are negatively charged

Lipid

What makes up plasma membrane, is a barrier for neurons, and keeps ions from being able to move back and forth across the membrane

Proteins

What spans the membrane, does most of the work inside the cells, controls the passage of ions via ion channels and has pumps that maintain the concentration gradients

Inside the cell

Where there is more potassium in a cell

Outside the cell

Where there is more sodium in terms of a cell

What pumps do

Maintain concentration gradients

Diffusion

Movements of ion from regions of high concentrations to low concentrations

Electrical Force

In an electrical field, the charged particles will move to their opposite charges and be repelled by like charges

Equilibrium potential

When the two forces that act on an ion (diffusion + electrical force) are in equilibrium

Current (I)

The movement of ions

Conductance (g)

The ability to flow - inverse of resistance

Voltage (V)

The difference in charge

Ohm’s law

I = g*V

-65 mV

Resting membrane potential for a healthy neuron

Nernst equation

The equation that tells us the equilibrium potential for a single ion

Goldman equation

The equation that tells us if the equilibrium potential is permeable to more than one ion

The ion that the membrane is most permeable to at rest

Potassium

Relationship between driving force and E_ion

What happens when you move away from E_ion and the driving force increases

All-or-none property of action potential

The term for the idea that action potentials are the same size and amplitude efvery time

Coding of strength of action potential

The frequency of action potentials

Hyperpolarize

When the membrane potential becomes more negative

Depolarize

When the membrane potential becomes more positive

Resting potential → graded depolarization → threshold → rising phase (sodium comes in) → overshoot → falling phase (potassium leaves) → undershoot

Phases of action potential

Absolute refractory period

The term for once an action potential is initiated, it’s impossible to trigger another one for at least 1 ms

Unidirectional aspect of an action potential

When an action potential moves, it moves down the axon in only one direction

Influences on speed of actional potential

Diameter of axon and presence of myelin (myelin facilitates flow)

Na_V channels open inward, quickly, and aren’t open very long

Characteristics of Na_V channels

K_V channels open outward, are more delayed, and stay open longer

Characteristics of K_V channels

Threshold

Na_V gates open

Falling phase

Na_V gates close

Absolute refractory period

Na_V gates are inactivated

Nodes of Ranvier

Gaps between myelin along the axon

Purpose of Nodes of Ranvier

Regenerates action potentials

Tetrodotoxin

A toxin that blocks Na_V channels

Why tetrodotoxin is toxic

This is toxic because it causes the inability to contract muscles

Otto Lowei and frog heart experiment - stimulated vagus nerve in one heart and transported fluids from Heart 1 to Heart 2 but Heart 2 even slowed down despite not being directly stimulated

What led to the discovery that neurons can communicate via chemicals

Electrical Synapse

A synpase that functions as a direct channel between neurons

Chemical synpase

A synpase that uses chemicals (neurotransmitters) to bridge the space

When electrical synapses are common

In embryonic development and in invertebrates/non-mammilian vertebrates

Peptides, amines, amino acids

Major neurotransmitters

Peptides are synthesized in the soma and transported down the axon

Synthesization and transportation of peptides to axon terminal

Amine and amino acids are synthesized locally (at synaptic terminal) and transported via being loaded into vesicles

Synthesization and transportation of amine + amino acids to axon terminal

Calcium causes vesicles to fuse with membrane and release its contents - exocytosis

How vesicles bind to membrane and what the role of Calcium is

Ligand-gated ion channels

Channels that are activated by ligands

Ionotropic Receptors

Another name for ligand-gated ion channels

Ligand

A molecule that binds (e.g. neurotransmitter)

How ligand-gated ion channels work

Channels that open or close to let ions pass when a specific chemical messenger binds to them

Excitatory Post-Synaptic Potential - depolarizes postsynaptic membrane so it’s closer to action potential threshold

When a ligand channel opens and positively charged ions enter

Inhibitory Post-Synaptic Potential - hyperpolarizes synaptic membrane so that it’s farther away from action potential threshold

When a ligand channel opens and negatively charged ions enter

Glutamate - positively charged - ionotropic receptors

Primary excitatory neurotransmitter

GABA - negatively charged - ionotropic receptors

Primary inhibitory neurotransmitter

Diffusion of excess neurotransmitter away from synapse, reuptake and recycles back into vesicles, enzymatic breakdown in synapse

How excess neurotransmitter is removed from the synapse

Ligand-gated ion channels directly open, GPCRs activate intermediate intracellular G-proteins

Difference between ligand-gated channels and G-protein coupled receptors