Final Review Flashcards
Mechanisms for maintaining a voltage across a neuron’s membrane
Selective Permeability: lipid bilayer that separates the extracellular from intracellular space allows some substances to pass through, but not others
Active ion transport: specialized pumps within the lipid bilayer that pump ions in and out of the cell
Action potentials
produced by voltage gated ion channels
propagated down the axon, from the soma toward the synapse
When a presynaptic neuron fires an action potential, it causes a postsynaptic potential in the postsynaptic neuron.
Axon hillock
Cone shaped region where the axon emerges from the soma. Contains a high density of voltage gated channels
EPSPs and IPSPs
At the Summation at the Axon Hillock, EPSPs add in mV, while IPSPs reduce
Synapses
briefly translate electrical action potentials into chemical signals, then back into electrical signals.
When an AP arrives at the Synapse, it activates voltage gated calcium (Ca2+) channels, which allow calcium levels to increase in the presynaptic terminal, which causes vesicles to fuse with the membrane of the presynaptic terminal, releasing neurotransmitter into the synaptic cleft.
Synaptic Vesicles
small bags filled with neurotransmitters, just waiting in the presynaptic terminal for an action potential to arrive.
Ionotropic receptors
fancy ion channels. Neurotransmitter molecules bind directly onto ionotropic receptors. This causes a conformational change – the receptor changes its shape, which allows ions to pass through.
Different ionotropic receptors allow different ions to enter the postsynaptic neuron. Those that allow cations to enter are excitatory synapses and produce EPSPs. Those that allow anions to enter are inhibitory synapses and Produce IPSPs
Metabotropic receptors
indirectly allow ions to enter the postsynaptic neuron. Neurotransmitter molecules bind directly onto metabotropic receptors too. But these receptors do not allow ions in. Instead, they activate G proteins (also called second messengers), that bind to ion channels from the inside, allowins ions to enter the postsynaptic neuron.
G proteins
Talk to other machinery inside cell to facilitate synaptic plasticity.
Can be activated by metabotropic receptors to bind to ion channels from the inside allowing ions to enter the postsynaptic neuron.
Drugs and Neurotransmitter Receptors
Neurotransmitters are endogenous, produced from within, agonists of neurotransmitter receptors.
Drugs that mimic or potentiate the actions of a transmitter are called exogenous agonists.
A partial agonist only partially activates a receptor.
Drugs that reduce the normal action of a neurotransmitter are called agonists
Psychedelics (Hallucinogens)
Hallucinogens act on serotonin receptors.
LSD (acid) is a serotonin receptor agonist
Psilocybin (magic mushrooms) are agonists for serotonin receptors and bind particularly in the prefrontal cortex
MDMA (ecstasy) increases extracelullar levels of serotonin (+ dopamine and norepinephrin) in part by blocking their reuptake. This leaves more transmitter in the synaptic cleft to bind to postsynaptic receptors.
Psychedelics (Dissociatives)
Dissociatives act on glutamate receptors
Ketamine: inhibits NMDA glutamate receptors by occupying the Ca2+ channel
Dextramethorphan (cough syrup) is metabolized to DXO, which is an NMDA receptor antagonist
Sensations are routed into the brain
Labeled lines: Nerve fibers that carry information about each sensory modality are segregated from one another, keeping sensory information about different modalities separate until they reach the brain.
Eventually combined together in the brain in a concept called binding.
There can even be labeled lines within a particular sensory modality, for different types of tough (light, stretch, pain, etc.)
Spatial Receptive Fields
Often have center-surround organization, which have three regions. They are most responsive to stimuli in the center. They are suppressed by stimuli in a ring around the center. And they are unaffected by stimuli outside the surround.
Attention alters neural responses
ERPs (which are measures of neural activity) made over primary visual cortex are different when a subject views the exact same image, depending on whether or not they are attending to it.
