spatial

Question 1

HM describe what happened to him

Answer 1

• don had intractible epilepsy
• surgeon Scoville removed about 7-8cm of the medial temporal lobe
• extracted all of that material by suction
• damaged amygdala, erihinal cortex, postrhinal cortex but primarily taking out the hippocampus

Question 2

Scoville and Milner paper (1950’s)

what did they argue

Answer 2

• the more the hippocampus was damaged, the more amnesic the patient
• concluded the hippocampus is the cause of amnesia
• thus the hippocampus MUST be a memory structure because if you remove it you get amnesia

important to note the extent of the lesion was wrong

Question 3

if we remove the hippocampus what type of memory is fucked?

Answer 3

episodic memory in particular

HM couldn’t form new autobiographical memory after the event

lived the rest of his life as a dense amnesic

Question 4

if the hippocampus is involved with (episodic) memory what happens if you put in electrodes and recode from them?

Answer 4

shockingly, discovered place cells.

different cells code different parts of the environment

cells form a cognitive map of the environment

Question 5

why is it so shocking that electrodes recorded in the hippocampus produced place cells

Answer 5

because we thought the hippocampus was a memory structure? now its a spatial structure? argggh whats the truth?

how do place cells relate to episodic memory?

Question 6

how do place cells help us form episodic memory?

Question 7

place cells in rat hippocampus vs episodic memory of human hippocampus - how can we explain the differences?

Just a different structure in rats vs humans ?

Answer 7

nope!

• much of the neuroanatomy from rats, monkeys and humans have preserved the regions - H structure just flipped 180 degrees with evolution
• place cells are also found in monkeys (Ludvig et al., 2004) and humans (Ekstrom et al., 2003; Miller et al., 2003)

evidence suggests that navigational and episodic functions are consistent across spiecies

Question 8

limitation of patient studies in humans - electrodes recording the hippocampal place cells

Answer 8

your recording form a dysfunctional area (its about to be taken out)

Question 9

place cells in rat hippocampus vs episodic memory of human hippocampus - how can we explain the differences?

Hippocampus is not a single structure - one part does episodic and one part does spatial memory

argue for this case

Answer 9

Well the hippocampus does contain many different structures. See changes in anaotmical structure itself, but also changes in anatomical connectivity

• e.g., DG - receives lots of input then only outputs to CA3. this is the input structure to the hippocampus
• subiculum hippocampal output - receives a lot of information from CA1 with modest output.
• basically, everything the hippocampus backs out to the cortex is via the subiculum

Thus maybe different types of input affect the function of a sub-region…

Question 10

Describe the trisynaptic pathway

Answer 10

Question 11

place cells in rat hippocampus vs episodic memory of human hippocampus - how can we explain the differences?

Hippocampus is not a single structure - one part does episodic and one part does spatial memory

argue against this point

Answer 11

there is no strict divide between one structure doing place cells and another structure doing episodic memory. we see place cells throughout.

also, we don’t see a lesion affecting episodic processes vs another lesion inducing episodic impairment

• patient RB - through loss of oxygen in surgery - lost only the cells of CA1 (bc those cells are very dense in glutamate receptors, these are highly energy requiring, if you remove oxygen those cells die before anything else)
• but this guy still had amnesia - so can damage small part of H and still get amnesia
• althought here does appear to be anatomical division, doesnt explain the place cell vs episodic memory debate

Question 12

Why should we strive away from episodic and semantic labels on things?

Answer 12

as a cognitive neuropsychologist, your aim is to put cognitive function onto biological units. Try to break the world down into cognitive functions. and this cognitive function should map onto a biological structure.

That mapping should reflect the computation of that region

so in doing this computation you achive these cognitive ability

terms like episodic and semantic memory are very arbitrary concepts - difficult to map these onto a structure. were too fixated. on things like episodic and semantic memory as terms which are very difficult to map onto biological processes

generic terms bad - reflect multiple component computations. yet were trying to define them ono a single region of brain

Question 13

reconciling episodic and spatial navigation in the hippocmapus

Relational processing and memory space

Answer 13

what do both episodic and semantic memory have in common?

• all objects are related to something - this glass is on the table
• there is a relationship with time, “yesterday” or “just after we went to the beach
• in building relationships between items and spaces in time we form an event memory

similarly with navigation

• walk from part b along this line to point B then along this line to point C
• allows you to learn a geometric relationship between those things
• can say this is starting point and this is the end - can only work that out because you’ve formed a relationship between the different points

Eichenbaum argues that both navigation and episodic memory share this feature - you try to relate things to one another. need to bring the relationship between things together to achieve either of these goals

Question 14

eichenbaum quote reconciling link between episodic memory and spatial functions in the hippocmpaus

Answer 14

rather than thinking about navigation in a spatial world think about how your brain is full of memories. the hippocampus is helping you relate between things you can navigate your memories

if asked what you had for breakfast this morning vs what did you have for breakfast yesterday morning you can answer both of those by forming relationships between the information you need to know: breakfast + this morning; breakfast + yesterday morning ( a different relationship)

so basically you navigate memory space rather than navigating geometric space

Question 15

evidence support for relational processing?

Answer 15

Wood et al (2000)

• found not all place cells just represent space
• not just a map of where you are
• it can also be a map of where you are in relation to what your doing

deign

• figure of 8
• rat told travel up line go left, then travel up and go right - do this repeatedly

found

• place cells exist that represented all areas of the maze
• cells representing the middle of the maze - which n travel down in both circumstances
• found that some cells (blue ones) oNLY fire when your in that space and about to turn left
• other ones (red ones) only fire when you are in this space and about to turn right

no longer cells that represent only spatial information. now represents information about where you are and its relationship with what you’re going to do

Question 16

how did wood et al (2000) study support the relational processing theory?

Answer 16

because if these cells are actually not interested in where. you are but the relationship between things

and space comes out because its easy to see

but actually if it’s interested in other types of relations as well i.e., what you are about to do then we can understand the hippocampus as a structure relating things together

Question 17

does the relational processing theory (Eichenbaum) also account for the issue of time?

Answer 17

Eichenbaum (2013)

• argued he was showing hippocampal place cells also represent time

design

• animal ran around track
• here animal sees object, dalay period, then knows it will get an odor

results

• during the delay
• when the animal is thinking oh i’m going to get odor 1, during the 10-second delay, we see a cell fires at the first second then switches off, then another cell fires the second seecond then switches off and so on

so he argues just as place cells mark a space in an environment, we have time cells that mark different time in environment

Question 18

when it comes to episodic memory - most people would argue that time is a critical part of episodic memory. why?

Answer 18

• firstly bc you can locate a memory in time - e.g., what you have for breakfast today vs yday vs last sunday
• secondly, when you remember an event - most of us have an internal visual image of the event as you experienced it, you know you arent hallucinating. you know its a past memory.
• what edward tolling called “a sense of pastness”

Question 19

did Eichenbaums odor study acc find time cells?

Answer 19

yes

• so you might argue oh its just computing space - but he did another study where the animal was on a treadmill and you still see these cells fire so not doing space but time

yes

• argues against precession because in that you can vary the length of the delay
• find some cells at the start are fairly consistent so regardless of whether its a short or long delay the same start cells switch on and off
• however, cells near the end of the delay have a much longer firing
• the shorter the firing range of a cell the more discrimintory your abiltiy is - fewer cells on at a time, so you know when these few cells are active were at this half a second period
• but near the end - last 4 seconds lot of cells are active. difficult to determine whether youre at second 4 or second 8
• no matter how many times you do this study your disciminatory ability is better early one than later on
• argues phase perception isn’t what’s going on because you would expect that firing to be fairly standard throughout the delay
• you wouldn’t expect it to be delay-dependent - shorter at the start and longer firing at the end

yes

• in his study 2014
• found if you extend the delay it alters the behaviour of the start and end firing rates
• so instead of thinking in absolute time - 1 second 2 second, 3 seconds etc thikn of it in relational terms - shortly after the onset, shortly before the offset - makes more sense
• those are relational terms of time
• purple lines - its expecting this to end

so

• “time” - many different types of time
• problem when you call something a time cell, what sort of time is it actually measuring?
• all of this makes more sense in a relational time manner
• okay its started now, now im still going on this treadmil, okay still going getting a bit bored, okay now its nearing the end woo

Question 20

what do we need to consider when using IEG’s to look at

Answer 20

• well there’s always gonna be bare cells firing - so your control group needs to be VERY good. like with fMRI
• need to ensure you are comparing it with something comparable so you aren’t making mistakes in the reduction
• also need time for these genes to express themselves - so you need the animal to do something then wait a bit
• then you need to kill the animal - as you cannot image this through the skull - get slices and inspect them
• gives you a kind of spatial detail that yuo dont get with fMRI as were looking at individual cells that were active during tha time

so its a powerful technique with some limitatinos

Question 21

immediate early genes (IEG) what are these?

Answer 21

• when cells fire, a cascade of proteins that occur
• genes switch on - produce proteins in order to carry out the function of that cell when it fires (to return, to recycle proteins, to release NT’s)
• there are immediate early genes that switch on as soon as cell fires
• basically, genes that activate rly quickly to say right. this cell is now active, and starts those protein cascades
• if you attach a dye to those genes when they switch on, means you get a snapshot in that cell.
• so could look at a whole slice of brain, the cells that are dyed mark the genes are active
• and the genes are active in the cells that have just fired

Question 22

Wan et al (1999) - 1st part when shown the novel and familiar

Answer 22

study design

• paired imaging
• rat’s eyes are on the side of their head
• rat puts nose in hole and each eye is exposed to a different screen
• one hemisphere processes one image e.g., familiar picture and the other processes another e.g., novel picture
• compare activation in the same structure in each hemisphere
• subtract activation from one hemisphere from activation in another hemisphere - the difference you are looking at here is the difference between novelty and familiarity
• very clever design, animal can act as its own control

results

• activity in the hippocampus does not distinguish between novel and familiar objects

Question 23

what is postrhinal in the rat called in monkey/humans?

Answer 23

parahippocampal gyrus

Question 24

what happens in the hippocampus when you look at a picture?

Answer 24

fuck all - activity in hippocampus is same when you look at novel vs familiar pictures

other areas however e.g., perirhinal cortex care about seeing novel pics vs familiar

adds weight to the Angleton and brown perspective that semantic memory relies on structures outside of the hippocampus. it’s evidence like this. that object memory recognition isn’t hippocampal - occurs in areas like. theperihinal cortex

Question 25

Wan et al (1999) - 2nd part when shown items in novel and familiar locations in space

Answer 25

* now what's novel or familiar is not just the picture - it's the relationship between picture and location * NOW the hippocampus cares * 2 subregions of h - DG and subiculum - activate MORE with familiar arrangement of items compared to novel arrangment of items * CA1 -opposite - likes novel arrangements more than familiar so same structures that previously didn't care about the objects, care about the same object's relational positions in space. strong evidence support for Eichenbaums relational processing claim. shows H doesn't care about things, but relationships between things

Question 26

dumbed down - what's the relational process hypothesis saying?

Answer 26

all the hippocampus is doing is relating something to something else whats when you lost your hippocampus you cant navigate and cant form episodic memories because they are all about relating something to something else

Question 27

Scene construction theory Hassabis and Maguire (2007, 2009)

Answer 27

Hippocampus = the ability to build spatially coherent scenes * when remembering a memory you have a spatially coherent scene - not like a room where. the geometry of the room is weird, warping and disturbed * when giving directions to somethere - you form a scene in your minds eye that allows you to guide someone to that location

Question 28

What things led to the idea of hippocampus doing spatially coherent scenes

Answer 28

* Gaffan's 1994 - scene memory hypothesis * eccot - spontaneous cognition memory in ray

Question 29

Gaffan's 1994 - scene memory hypothesis

Answer 29

Argued that when you remember an event you remember the whole scene. scenes allow you to discriminate one event from the other. Discriminating breakfast from today vs yesterday is not done through time alone, but the fact that the WHOLE SCENE is different - different people, different things happening etc.

Question 30

how did Gaffan test scene memory hypothesis?

Answer 30

Gaffan (1994) * presented monkey touch screen * two foreground objects “X" and “O” in very specific locations * background of different colours/objects * animal learns that one of these two objects if they touch it they get a food reward * each of the two stimuli (each problem) is against a consistent scene, so X in THIS SCENE against THIS BACKGROUND will always be in top left Gaffan believed that would allow the animals to remember these problems… and he was right By the 2nd trial, animal got down to 20% error. and almost all of those errors were from things previously got wrong - animal made similar error. never made error when it was something they got right. by trial 8 n perfect.

Question 31

what does Gaffman's scene memory show?

Answer 31

* Showed that scene memory enables RAPID learning. didn't have to look at the scenes over and over to learn them. * episodic memory is spontaneous and quickly encoded. You have 1 experience with which you learn it. In the scene, the animal learns the objects much more quickly than if you told it to learn the objects alone. In fact he showed this, got them to do. the EXACT same task but just not in specific locations/not against a background scene - and animslas were much slower.

Question 32

Gaffman scene study - how did he show performance was hippocampal-dependent?

Answer 32

* Lesioned the fornix - disrupt hippocampal functioning * significantly slowed down how fast the animal learned this skill So putting objects in specific locations in specific scenes allows for rapid learning and that rapid learning is hippocampal-dependent

Question 33

how can a lesion of the fornix affect the hippocapus?

Answer 33

* fornix lesion is a lesion of white matter coming out of the fornix into the thalamus * you lesion the white matter you disrupt activity of the hippocampus * effective disruption of hippocampal function

Question 34

Which animals display scene memory dependent on the hippocampus?

Answer 34

* monkeys * rats * humans also shown dependent on the hippocampus as * amnesic n show impairments in scene memory * animal models of AD show severe impairments in scene memory

Question 35

can Gaffmans sene memory task be given to all animals?

Answer 35

episodic memory is a conscious thing that we have. But it doesn't have to be conscious otherwise animals like rats wouldn't have it The Gaffan task only explores scene memory in conscious animals - need a way to test it on rats.

Question 36

exploring scene memory in a rat spontaneous recognition memory - Eacott and Norman (2004)

Answer 36

rat is in an arena - square arena with 2 objects in it * first - animals like novelty * Vagely interacts with and encodes both objects * used rats preference for novelty to explore scene memory task/ episodic memory task design * different arenas - grey or a grid arena * the same two objects in each aren a, a cyclinder or a cube * after a delay, test phase - rat enters new arean a * but somethign is novel - seen the items, seen this background, what it hasn't seen is this object in this location. results * animal prefers the novel things - the cube in the right on a grey background * means they have a memory for what they have scene, where they seen it and what context it was in * basically an operationalisation for episodic memory - (basically a where which when memory) i have a problem with this - doesn't Gaffan say that the construction of the entire scene is what allows us to distinguish one scene from the other? but here only the novel item and location is “novel?” shouldnt the inclusion of a new item change this into an entirely different scene, shouldnt the animal be stimulated by it all?

Question 37

rat interacts with items then shown a novel one and interacts with that more how does a rat preferring novel items show they have memory?

Answer 37

Because if it recognises this is new then it has remembered the other, old and familiar items. indirect measure of memory

Question 38

what did spontenous object memory allow (2 thngs)

Answer 38

* us to investigate episodic memory without caring about conscious experience * allows you to study episodic memory in very young children as they cat use language to explain things - so you kinda treat the children as rats - language and episodc memory - hypothesised develop around the ages of 4 - but a child of 18 months can complete this task * to explore episodic memory without caring about time

Question 39

why do people NOT think episodic memory does time

Answer 39

we're really bad at time - when remembering an event we work out when it happened by some non episodic mechanism. so I cant remember I went to sunny beach in 2014 but I only know that because was during the summer holidays after sixth form my understanding of when something happened is based on non-time information. kinda like the spontaneous recognition memory study as the animal knows this object is novel because it wasn't there in either trial and wasn't against this background in either trial. you compare it to other stuff and through that extract the thing you are looking for.

Question 40

Spontaneous object recognition (where-what-which task) how does a hippocmpal lesion affect this?

Answer 40

fornix lesions showed this task was hippocmpaal dependent. * 0 is chance and 1 is perfect peformance * animals with no lesion (sham) = good at task * lesion of perihinal cortex (pe) = good at task * lesion of postrinal cortex (po) = good at task * disruption of hippocmapus through = CANT do task

Question 41

interestingly both the what which and when task + the scene memory task were shownt o be hippocampal dependent

Answer 41

but i guess in both they did what where and which

Question 42

the what where which task. -could just argue that the reason the hippocampus is invlved is bc H does spatial and theres a spatial element to this task. argue against this

Answer 42

* instead of making rat do what where which * they do what where task * completely fine doing this despite hippocampal lesion

Question 43

how did the what where-which-task and what-where task (Eacott and Norman 2004) disprove Eichenbaum's theory of hippocampus doing relational processing.

Answer 43

both the what-where-which and what-where tasks a * because while the what-where-which task was hippocampal dependent * the what-where didnt depend. onthe hippocampus

Question 44

very interesting - Alzheimers animal model how did they show the hippocampus doesn't give a fuck about time?

Answer 44

The what were which task - shown to depend on the hippocmapus previously what-where task doesnt depend. onhippocmapus * rats * what-where-which * which is either determined by context vs time * alzheimers mice are only impaired when the which is determined by context there are other ways of solving time

Question 45

Maguire and Mullay quote on scene memory

Answer 45

Question 46

any evidence to support this?

Answer 46

Question 47

how can we test SCT in humans? understand amnesia using SCT

Answer 47

* so we know that episodic memory and spatial navigation depend on the hippocmapus * if SCT is true then amnesic n should be impaired in any skill htta requires sccene construction * so we can test other things that require scene construction and see if these skills are also impaired in amnesic n

Question 48

how is the scene in the minds eye of an amnesic patient

Answer 48

somewhat disturbed - "squished"

Question 49

can amnesic n imagine scenes?

Answer 49

no Hassabis et al., (2007)

Question 50

spatial coherence of the imagined scene in amnesic n how do we test performance objectively

Answer 50

**spatial coherence index** - (this only part of it - full experiential index captures full range of information) * ask n to judge how spatially coherent the scene feels * can you move around it? hows the geometry is it squashed/disturbed in controls - very spatially coherent image * however for amneiscs - get a negative coherent index * means they are describing things that aren't spatially feasible * however… 2 amnesics show good spatial coherence. * interesting…?

Question 51

patient 1 and Jon really good at the scene construction task - scored highly on the spatial coherence index doesnt this disprove the SCT theory?

Answer 51

we can explain these two outliers * both had only half their hippocampus damaged * so, while half a hippocampus isn't enough to stop n being amnesic is it enough to have them spatially construct scenes Mullally et al., 2014 * neuroimaging while they imagined hypothetical events * told to imagien things, tone sound told them to open eyes and stop * then they rate how difficult it was PO1 and jon results * the remaining bit LEFT and RIGHT hippocampus was active during the task * so whats left is able to support some construction of scenes jon * remaining LEFT hippocampus was being used * also activated the retrosplenial cortex more than P01 and controls * regions that we wouldn't normally use * is this compensatory activation for the lack of R hippocampal activation?

Question 52

what did we learn from Mullaly eta l., 2014 study of jon and PO1?

Answer 52

they can use the remaining structures to do scene construction but its not normal * Jboth can do this but jon , whos using additional structures says he finds the task very effortful, that the scenes arent instant pictures, and whiles he capable doing it he doesnt. dothis normally * so his internal picture ight be the same but it certainly isnt constructed in the same way we constuct the scenes

Question 53

is SCT right?

Answer 53

well SCT would predict that amnesics should struggle with other, scene-based tasks, and that is what we find true so… can add this to other evidence support for the theory

Question 54

what other ways have people investigated scene construction in patients? boundary extension effects

Answer 54

* asked to draw image * controls draw it zoomed out 60% of its true size * amnesic patients consistently draw an accurate depiction

Question 55

how does the boundary extension effect task support SCT

Answer 55

That task showed a really weird thing where amnesics have an advantage in memory loss. Thus hippocampal amnesic cannot be defined by memory loss but instead has to be something underlying some computational mechanism like scene constructuion that can explain it

Question 56

how does SCT explain the boundary extension study?

Answer 56

* normal people take the image and extend the boundary * how have we extended the boundary * because the hippocampus creates a scene that exists beyond the one we have scene * if you don't have a hippocampus and cant construct scenes you are unable to extend the boundary * so all you can remember is what you saw - perform better than someone who naturally extends the boundary

Question 57

why is SCT better than “episodic” or “spatial memory” terms

Answer 57

explains the computational mechanism of the structure * explains how h does both episodic and semantic memory * can make predictions about what we'd expect impaired from amnesic n * explains how we can get paradoxical better memory in amnesic patients - which we couldn't explain if we labelled the hippocampus a memory structure

Question 58

Gaffan's paper “against memory systems” what was the paper about

Answer 58

* the idea that maybe trying to think about memory and trying to find which system does semantic, which system does procedural memory, which system does episodic etc * we're thinking about it the wrong way * because. we aren't talking about a single computational process * the paper argues all brain cells are capable of plastic responses * plastic responses are remembering * so if the cells in V1 represent. a corner, then those cells are capable of remembering a corner - you don't say this cell remembered this corner then sends that information somewhere else for it to be remembered * where you perceive is where you remember because the computation that's being done is the perceptual computation * so argues what the hippocampus is doing is the perceptual computation around scenes * measns scenes are remembered in the hippocampus - because scenes are constructed in the hippocampus

Question 59

the boundary extension effect - where amnesic have better memory than controls - is it true if n just see pictures

Answer 59

yes! Mullaly et al., 2012 * n see picture * then see second picture asked if it's a) same b) closer up or c) further away * controls confidently (and inaccurately) say its closer more often while experimental patients always say

Question 60

extension how can we explain the boundary effect

Answer 60

* when viewing close up scenes we automatically extrapolate beyond the physical edges of a scene * e.g., with a cat, understand the tail extends and behind that tail extension theres more grass prob beyind * hippocapmus understands and does the computations for this * so you construct boundaries using your understanding of how the world exists * v cool - the BE effect (the extended scene) is what you acc remember. Compare memory against the picture you constructed, not the one you seen its the extrapolating additional details beyond the boundaries of the scene that patients might not do

Question 61

Chadwick et al., 2013 - what did this study show

Answer 61

the boundary extension effect is hippocampal dependent * if you are about to make a BE error then the hippocampus is active at the time of ENCODING * not happening in the reconstruction of the memory - but at encoding * when first seeing it - you immediately construct the zoomed out image in your head

Question 62

what computations have people argued unite the function of hte hippocmapus that satisfy both episodic and spatial functions

Answer 62

* Eichenbuam and Cohen 2014 - the computation occuring is the relationship between things * Maguire and Mullaly 2013 - the computation occuringg is to construct the spatially coherent scene of a memory/navigation