hippocampus

Question 1

what are the parahippocampal and perirhinal

Answer 1

connections between association cortices and hippocampus

Question 2

removal of medial temporal lobe (both sides) results in what

Answer 2

severe anteriograde amnesia - like clive wearing

Question 3

hippocampus roles

Answer 3

declarative/ explicit memory formation

tells u where u are in the world aka spatial memory / learning

often lost in early alzheimers

active site of neurogenesis

pattern completion

pattern separation

Question 4

what is pattern completion

Answer 4

recognising something from a partial representation

unique to each of us. e.g. donald trump we see, emotional memory we think about apprentice vs news vs debates etc

Question 5

what is pattern separation

Answer 5

learning to distinguish between similar things e.g. diff types of chocolate

Question 6

how do neuronal signals travel along vs between neurons

Answer 6

along = electric AP

between = chemical NS

Question 7

what are excitatory neurotransmitters

Answer 7

inc probability of target neuron firing action potentials

Question 8

what are inhibitory neurotransmitters

Answer 8

dec probability of target neuron firing action potentials

Question 9

how many neurons approx in our brain

Answer 9

86 billion

Question 10

what is a code / what does it dictate

Answer 10

neurons fire code representing dog etc

code causes neurons to fire

code dictates how often neurons fire

code dictates how long they fire for

code dictates where they project to

code dictates how many other neurons they are connected to

code dictates numbers and types of neurotransmitter receptors

etc

Question 11

what is hippocampal indexing

Answer 11

the basis for retrieval - for pattern completion and pattern separation

Question 12

5 most important subregions of hippocampus

Answer 12

subiculum

ca1

ca2

ca3 (most important)

ca4

Question 13

neurocortical association areas send info to perirhinal cortices. this goes to entorhinal cortex then where

Answer 13

hippocampis - esp CA3 for pattern matching thne goes out to cortices then frontal cortex to decide what to do

Question 14

role of subiculum

Answer 14

communicates with subcortical areas/ limbic system - emotional memory

dictates how we feel about memories

Question 15

process of hippocampal indexing

Answer 15

pattern of neuronal activity from cortex activates a specific group of neurons in CA3 - aka partial representation sent to hippocampus

in hippocampus CA3 dictates best possible match , full representation made / full code activated

this sent back to cortex

Question 16

what is synaptic plasticity

Answer 16

cellular basis for learning and memory

Question 17

intracellular conc of na+ at rest

Answer 17

15

Question 18

intracellular conc of K+ at rest

Answer 18

100

Question 19

intracellular conc of ca2+ at rest

Answer 19

0.0002

Question 20

intracellular conc of cl- at rest

Answer 20

13

Question 21

intracellular conc of A- at rest

Answer 21

385

Question 22

extracellular conc of Na+ at rest

Answer 22

150

Question 23

extracellular conc of K+ at rest

Answer 23

5

Question 24

extracellular conc of Ca2+ at rest

Answer 24

2

Question 25

extracellular conc of cl- at rest

Answer 25

150

Question 26

extracellular conc of A- at rest

Answer 26

0

Question 27

what occurs in excitatory neurons

Answer 27

ligand gated channel ligand = neurotransmitter when ligand binds, conformational change in channel, sodium can flood down into neuron down conc gradient thus, elect diff between outside and inside is reduced when this happens enough, threshold triggered thus voltage gated sodium channels open causes action potentials to fire

Question 28

what is long term potentiation - ampa and nmda receptors

Answer 28

freq firing of AP strengthens synapse presynaptic axon terminal - glutamate postsynaptic dendrite - ampa receptors glutamate binds to ampa, allows na+ to flood in through receptors, triggers action potential ndma receptors on postsynaptic dendrite - glutamate binds to these when no more ampa receptors allows calcium ions to flood in causes inc ampa receptors on postsynaptoc dendrite thus, more action potentials fired - strengthened synapse, this is a long lasting change and occurs anywhere in brain

Question 29

where specifically does long term potentiation occur

Answer 29

synapse between ca3 and ca1

Question 30

ca3 other name

Answer 30

schaffer collaterals

Question 31

ca1 other name

Answer 31

pyramidal cells

Question 32

what is long term depression

Answer 32

connections between neurons become weaker lower intensity, less freq of ap firing dec expression or insertion of post synaptic ampa receptors, dec presynaptic glutamate release

Question 33

how does code go to memory

Answer 33

idk one theory is code is a pattern of firing of a specific group of neurons in a specific hippocampal region - ca3 firing pattern activates memory recreates representation in association cortices

Question 34

excessive or exogenous glutamate can cause what

Answer 34

exitotoxicity serizures as systemic nmda and ampa activation

Question 35

med for stroke/ alzheimers

Answer 35

memantine/ ebixa blocks nmda-r

Question 36

2 types of spatial representation

Answer 36

allocentric egocentric

Question 37

what is allocentric representation

Answer 37

non egocentric map of the environment object to object/ place to place occurs in hippocampus

Question 38

what is egocentric representation

Answer 38

where i am in environment me to place/object mostly posterior parietal cortex and prefrontal cortex, a little bit hippocampus

Question 39

what are place cells

Answer 39

neurons that fire when ur in a particular place pyramidal neurons activated by allocentric environmental cues mostly visual but can include other senses also activated by replays of cues aka thinking about memories of what u did in a place place cells encodes a place field, which can be change some spatially oriented

Question 40

how does hippocampus achieve allocentric representation

Answer 40

place cells

Question 41

other than place cells, what other neurons are navigational - 4

Answer 41

head position cells border cells reward place neurons grid cells

Question 42

where are head position cells

Answer 42

subiculum - on the way to hippocampus

Question 43

what are head position cells

Answer 43

navigational - fire when head is oriented to specific direction duh

Question 44

what are border cells

Answer 44

place cells specifically activated by barriers

Question 45

what are reward place neurons

Answer 45

learn about specific place where a reward is - not value of rewards (value happens in orbitofronal cortex)

Question 46

what are grid cells

Answer 46

tells place cells wya hexagonal map the more u learn about place directions, more hexagons maybe how we measure distance? path integration - where u are relative to where u were speed, direction, distance that has been travelled - in bats, happens in 3d since they fly

Question 47

where are grid cells

Answer 47

entorhinal cortex in hippocampus