keep forgetting Flashcards
what binds to GFP to stabilise it when visualising neurones
M13 AND Calmodulin
Ventral pathway :
‘what’ V1,V2,V4, inferior temporal cortex
Dorsal Pathway:
‘Where’ V1,V2,V3, posterior parietal
when is glutamate released
by photoreceptors when depolarised
types of channels in On cells and OFF cells
on - metabotropic GluR
off - ionotropic GluR (excitatory)
illuminate centre of ON cell
illuminate surround of ON cell
centre - activated - depolarised
Surround - deactivated - hyper polarise
illuminate centre of OFF cell
illuminate surround of OFF cell
surround - activated - depolarised
Centre - deactivated - hyper polarise
what receptors occur in olfactory in mammals and insects
mammals - GPCRs
insects - Ion channels
Drosophila olfactory pathway
Olfactory receptor neuron
Glomeruli (antennal lobe)
Local neurones
projection neurones
Mammals olfactory pathway
Olfacotry sensory neurone
Glomeruli
Granule/ perigranular
Mitral and tufted
Innate olfactory features
innate: Categories Cats Dense Dont Prefer certain odours Prefer Stereotyped Salmon
Lateral horn and Amygdala
Learned olfactory features
Learned: Discriminate Dog Sparse Still Arbitrary Ate Random Rabbit
Piriform and Mushroom Body
olfactory transduction pathway steps
Oderant Receptor Golfs Adenylyl Cyclase cAMP Na and Ca channels Cl channels Depolarisation
which tastes are metabotropic which are ionotropic
M: umami, sweet, bitter
I: salt, sour
taste transduction pathway stages
Taste buds brainstem VPM of thalamus Insula Parietal Cortex
inner hair cell resting potential
-60mV
hair cell hyper polarised potential
-65mV
OHC features
V shaped bundle, innervated by efferent fibres, preston motor protein that contract in response to Cl- movement, connected to the tectoal membrane
outer hair cell resting potential
-40mV so respond faster than IHC
stages in the auditory transduction pathway starting after hair cell depolarisation
cochlear nucleus superior olivary complex inferior and superior colliculus Medial geniculate nucleus auditory cortex
role of the Medial geniculate nucleus
memory and learning
role of the colliculus in auditory system
integration of auditory and non auditory inputs
hierarchical model
Edges Contours Parts of object Point of view View Invariant Categorisation
hubel and wiesel experiments
V1 cortex in cats
difference between simple and complex cells in in the cortex
Simple cells : layers 4 and 6 and have an elongated receptive field that responds if stimulated in the centre of the receptive field
Complex : layers 2, 3 and 5 and collect information from simple cells with the same orientation, responds if stimulated anywhere in the receptive field
disadvantages of the hierarchical model
doesn’t take feedback from higher cortical areas into account and poor scale
optic tectum ablation leads to
lose orientation reflex
difference between sound in vertical and horizontal planes
Sound elevation in the vertical plane has monaural cues, sound position in the horizontal plane has binaural cues
what do command neurones control
saccadic eye movements
neurotransmitter released by amacrine
inhibitory - GABA
neurotransmitter released by bipolar cells
excitatory - glutamate
LSO-MNTB binaural excitatory-inhibitory (EI) pathway:
Detects interaural level differences (ILDs)
detected by cells in lateral superior olive
LSO receives excitatory input from ipsilateral side and indirect inhibitory input from contralateral side.
MNTB converts excitatory input from contralateral aVCN to inhibitory, to inhibit the LSO
The position of a sound around the head is determined by the arrival of excitatory and inhibitory inputs (coincidence)
Binaural Excitatory-Excitatory (EE) Pathway:
Detects interaural timing differences (ITDs)
Requires the coincidence from both ears but both inputs are excitatory
ITDs are encoded by cells in the MSO that compare the coincidence of excitatory ipsilateral and contralateral inputs.
The overall position of a sound is encoded by the balance between the average population response of the two MSO channels.
what is habituation
Habituation is the depletion of the synaptic vesicle pool,
> 50% lower quantal release
what is sensitisation - simple bear model
Protein Kinase A (PKA) phosphorylates and inactivates K+ channels, longer depolarisation means more vesicular release
Simplified hippocampal circuit:
main input is the entorhinal cortex to dentate gyrus (perforant),
a synapse links dentate gyrus to CA3 (mossy fibres),
a synapse links CA3 to CA1 (Schaffer collaterals),
output via fornix and subiculum
LTP Mechanism:
LTP Mechanism:
Glutamate activates AMPA and NMDA receptors
AMPA depolarises the membrane and a Mg2+ block is removed from NMDA
NMDA receptor mediated by Ca2+ activates calmodulin kinase II (CaMKII)
Activation of PKA translocates to the nucleus which triggers gene expression causing increase in sensitivity of the AMPA receptor
role of cAMP in LTP
activated by PKA it then binds to CREB to regulate gene expression
what is LTD and what are the 2 types
decrease in EPSP occurs in hippocampus and cerebellum
de novo - there was no previous potentiation
Depotentiation - removal of previous LTP
difference between parallel and climbing fibres
parallel - 1 synapse on many Purkinje cells, release glutamate that binds to and activates GluR and AMPA
Climbing - many synapses with 1 purkinje cell, releases Na+ that depolarises the purkinje
role of kenyon cells
Kenyon cells receive input from multiple projection neurons and require multiple simultaneous inputs to fire (selective)
- Kenyon cells sample small regions in projection neurons, this turns a dense combinatorial code into a sparse selective code
what are the subdivision of the kenyon cell axons
Kenyon cell axons are subdivided into compartments by innervation of mushroom body output neurons (MBONs) and dopaminergic neurons (DANs)
DANs are paired with MBONs of the ‘opposite’ valence- this predicts that learning should happen by weakening synapses
FOXp mutation in the fly leads to …… why?
longer to make decisions
FOXP regulates K+ channels so if mutated more K+channels in kenyon so hyper polarised and takes longer to depolarise
name 2 channels that small molecules can pass through when fixing faulty circuits
TRPV1 and P2XR
The GAL4/UAS System used for
: Allows us to artificially express arbitrary transgenes in specific cells
GAL4 consists of…
GAL4 consists of two domains- a DNA binding domain and an activation domain
Difference between forwards and backward pairing of the Kenyon cell MBON synapse
forward pairing depresses Kenyon Cell-MBON synapses
backward pairing potentiates Kenyon Cell-MBON synapses
Kenyon cells have two different dopamine receptors…
DopR1 signals to Gs proteins
DopR1 is important for forward learning (no calcium)
DopR2 signals to Gq proteins
and DopR2 is important for backward (uses calcium)
what do Gs and Gq activate –
- Gs activates adenylyl cyclase cAMP
* Gq activates PLC which makes IP3, causing the release of Ca2+ from the ER (used in backward learning only)
difference between mushroom body and cerebellum in learning
in the insect mushroom body training reduces the “wrong” behaviour
The cerebellum mediates motor learning by partly correcting “wrong” movement’
What will the main functional consequence be if half of the number of ribbon synapses in an inner hair cell degenerate?
The cell would not be able to encode the full range of sound intensity
What is the main functional role of the inner ear oscicles?
a. They transform air compressions into liquid motion
Mice with mutated and malfunctional Cav1.3 Ca2+ channels are deaf because:-
c. There is no neurotransmitter release from the hair cells
What is the primary functional consequence of the lack of endocochlear potential?
. The driving force for K+ entry into hair cells through the transducer channels is removed
The inner hair cell resting transducer current is important because:-
. It sustains a level of afferent activity that can be reduced or increased
What is the main difference in the mechanism responsible for detecting binaural timing differences in mammals and birds
In mammals they are represented by two hemispheric channels and in birds by labelled lines
What is unique about the representation of stimulus location in the auditory system compared to that in the visual system?
he location is not represented in the topography of the receptor cells in the auditory system
What factors determine an animal’s preferred mechanism for localising sounds in the horizontal plane?
The size of the head and the mechanical limitations of the auditory system
Why has the hearing range of some mammals evolved to become extended towards the lower frequencies
The animals have become bigger and their territories have become larger
Why does visual information usually dominate in the sensation of topography?
It is a more reliable representation
How does olfaction differs from other sensory modalities
The physical characteristics of light and sound can be described quantitatively along a few dimensions, whereas odorant molecules cannot.
in the mouse olfactory bulb, blocking synaptic transmission in these neurons, prevents them from signalling to other neurons. what does this cause
] Mice would be less able to behaviourally discriminate between different odours
what technique revealed that the Drosophila mushroom body is tiled by non-overlapping compartments defined by innervation by mushroom body output neurons (MBONs) and dopaminergic neurons (DANs)
GAL4/UAS system
Why do Drosophila Kenyon cells respond so selectively to odours?
Kenyon cells require multiple inputs to fire simultaneously before they will fire.
what would be experimental evidence that a neurone is acting to accumulate sensory evidence according to the drift-diffusion model of sensory decision-making?
Its activity ramps up over time, reaching a threshold immediately before the animal makes a decision.
The inner plexiform layer (IPL) contains synapses between:
bipolar, amacrine and ganglion cells
in darkness what is happening at the cGMP channels
Most cGMP-channels in rods and cones are open
Magnocellular cells have
large and round-shaped receptive fields
what do complex cells respond too
Complex cells respond to a bar in certain orientation anywhere in the receptive field
Activation of halorhodopsin expressed in a neuron causes:
the hyperpolarisation of the neuron
attributes that make invertebrates useful model systems for the study of learning and memory
preparations from invertebrates do not require the same complexity of environmental control that equivalent preparations from mammals would do
and
the neuronal circuitry involved in regulating behaviours is often relatively simple
what is a defining feature of a Hebbian synapse
it requires co-ordinated activity in both pre- and post- synaptic terminals
what is AMPAfication
it involves the incorporation of new AMPA receptors into a synapse undergoing LTP
what may LTD result in
it may involve a reduction in the number of post-synaptic receptors.
