Neurophysiology Flashcards
What are dendrities
Branched extensions that receives input from other neurones
What is myelin?
Insulation of the axon making action potential non diminishing
What is an astrocyte?
A cell used to housekeep to take away excess glutamate and monitor activity in the synapse
What is back propagation?
Action potential flowing backwards into the dendrites
Where are action potentials made?
Axon hillock
Where do EPSP and IPSP travel from and to
From dendrites to the soma
What does action potential trigger?
Influx of calcium ions into presynaptic terminal causing movement of molecular machinery Ligand gated channels open and release influx of sodium
What is direct gating/Inotropic
Conformational change occurs in the shape of the receptor(channels have different sub-types)
Indirect gating/Metatropic
Use of G protein usually activated lutamate or GABA which changes the metabolic state of the cell
What are the 2 Types of synapses?
type I and type II
The difference between the synapses is the postsynaptic density
In the type I the population density is a bunch of proteins which hold the receptors
3 main receptors on Type I
AMPA receptor bind to glutamate and tend to depolarise the membrane
NMDA receptors have multiple sites and can modify easily and bind to glutamate put require a co-agonist(glycine), the receptor is ligand and voltage gated
Metabotropic receptors are g protein coupled controlling metabolism
What are the 3 classes of inotropic receptors
AMPA, NDMA and KA
What are meabotropic glutamate receptors/mGluRs?
A 7 transmembrane regions
controls brain cell function in seconds(neuromodulator) and is connected to secondary men
What is G proteins signalling
G proteins signal causing the activation of phospholipase C so that hydrolyses occurs for calcium to be released
What excitatory glutamate receptors do?
They allow passage of sodium ions and sometimes calcium ions and produce EPSP
Agonist:glutamate, AMPA and KA
Antagonist-CNQX,NBQX
NMDA glutamate receptor
Mediates slower synaptic responses because of conductance to potassium
The channel Na+, K+ and ca2+
Can cause Exocitoxicity
What is Exitotoxicity?
When the LTP and LTD is activated too much
What does magnesium ions do to NDMA receptor?
Magnesium ion Blocks pore and depolarisation happens magnesium is less attracted and allows for passage of ions
NMDA dual gating
Glutamate and depolarisation is needed to open
Also glycine is required as a co-agonist
Calcium and sodium enter the cell and potassium leaves the cell
What does GABAa do?
GABAa binds to sites between sub units makes the cell more hyper polarised
GABA effect time
GABAa is around 50-60 milliseconds
GABAb is around 500-1000msec
Name the sensory modalities
Vision smell taste touch thermal sense pain hearing retina
What is psychometric functions?
Fechner defined psychometric functions which is how big the stimulus compared to the intensity of sensation of what they feel
What are sense organs?
Sense organs are made by combining multiple different receptors
Example combination of mechanoreceptors gives fine sense of touch
What are rods?
Rods check black and white colour
What are cones?
Cones sense the amount of red, blue and green light
Types of firing pattern?
One type of firing pattern is one that fires at the start of a signal then calms down or fires at the start of a signal and adapts rapidly
First type is to tell that there is detection like someone pressure the skin(Rapidly adapting receptor)
The second type is to maintain the firing to show that pressure of the skin is still occurring(slow acting receptor)
Types of code
Rate code=Number of spikes Count code=How many spikes Temporal code=Precise spiking Phase code: Spike versus a rhythm Population code=Spikes between different neurones
What features does sensory neurones have?
receptive fields-region in the sensory periphery within which stimuli can influence the electrical activity of sensory cells.
spatial domain
many spatial overlap
How does relay neurone integrate sensory neurones?
The red receptor cell being excited causing the action potential to fire in the relay neurone which switches on the inhibitory neurones
The cognate red relay cell inhibits neighbours causing inhibitory surround
How is complex information processed in relay neurone?
Convergence of inputs(V4)- receives information through multiple neurones
What happens in the retina
The retina encodes components and the brain decodes components
What type of modulation does relay allow?
It allows top down modulation-Modulation of neural activity in neurons in lower-order sensory or motor areas based on an individual’s goals.
