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Lecture

HMB200H1 Lecture Notes - Place Cell, Head Direction Cells, Thalamus


Department
Human Biology
Course Code
HMB200H1
Professor
John Yeomans

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Lecture'23:'Memory'Systems'
Memory!
Memories!are!what!make!human!experiences!meaningful.!
Mental!diseases!are!disordered!emotional!memories.!
Life!experiences!are!coded!in!episodes:!episodic!memory!
Dementias!are!global!losses!in!memory.!
Aging:!dementia;!Alzheimer’s!!!long!term!major!loses!in!memory!
When!cortical!systems!are!disrupted,!we!cannot!reconstruct!memories!of!our!lives!!
Dementia:!aging!related!losses!of!memory!that!are!widespread!loses!due!to!widespread!forebrain!or!
cortical!damage!
Amnesias!are!more!specific!losses!
Memory!loss!after!injury:!retrograde!amnesia!
Loss!of!memory!after!injury:!anterograde!amnesia!!
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Types!of!Memory!
Reflexes,!fear/anxiety,!habits,!speech,!spatial,!life!episodes,!etc.,!all!learned!and!remembered!in!separate!brain!
areasParallel!systems.!
Declarative!vs.!NonKdeclarative.!Explicit!(“conscious”)!vs.!Implicit!(“unconscious”)!
Declarative!memories:!life!experiences!(facts!and!figures!of!events!in!our!lives)!!!we!are!aware!of!and!
think!about!=!part!of!conscious!experience!(Explicit!–!can!talk!about!=!aware!of!it)!
Undeclarative!memories:!also!called!procedural!memories!(reflex!memories,!habit!memories,!
performances!of!skills)!!!things!we!are!less!aware!of!(implicit)!
There!are!procedural!memories!that!are!explicit!or!implicit!
ShortKterm!(e.g.!working)!vs.!LongKterm.!
All!learned!and!remembered!in!separate!brain!areas:!parallel!systems!
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Types!of!long!Term!Memory!
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Declarative:!
" Frontal!Lobe:!Life!History!and!Plans!
o Episodic!memories:!facts!and!verbal!thoughts!
" Stored!in!frontal!lobe!(dorsal!lateral!cortex!for!episodic!memories)!!
" places!+!faces!=!series!of!events!of!our!life!story!
" life!history!is!organized!in!preKfrontal!area!(life!history!is!constructed!here)!
" more!associated!with!left!hemisphere!and!temporal!lobe!
o Semantic:!associated!with!speech!areas!of!left!cortex!
" Left!Speech!Cortex:!Semantic!memories!
" front!lobe!and!pre!frontal!lobe!for!planning!
" Can!be!many!forms!(faces,!objects)!
Procedural!
o striatum!and!basal!ganglion!–!important!for!remembering!where!to!go!OR!performing!specific!tasks!
o striatum!important!in!compulsive!acts!(OCD)!–!performing!repeatedly!!
" !involve!habit!memories!and!performances!that!involve!basal!ganglia!
" habit!learning!
o cerebellum!is!important!in!reflex!learning!
" Cerebellum:!Reflex!Delay!Conditioning!

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" performance!of!motor!movements!
" modifications!of!movements!in!reflex!learning!=!Pavlovian!learning!
o Hippocampus!and!Temporal!Lobe:!Formation!of!Experiences!and!Emotions!
" Hippocampus!involved!in!different!types!of!conditioning!than!cerebellum!
" Cerebellum:!important!for!learning!motor!reflexes!when!things!are!happening!
" Hippocampus:!important!for!learning!associations!of!things!that!are!separated!in!time!(trace'
conditioning)!
Simple!changes!in!procedure!can!change!the!memory!from!being!a!cerebellar!memory!
(implicit)!to!a!hippocampal!memory!(explicit)!
o Temporal!lobe:!important!for!identifying!faces!
" Identifying!faces!(object!memory)!gets!converted!into!emotional!memory!–!occurs!in!left!temporal!
association!cortex!
Hippocampus!is!important!in!converting!this!into!emotional!memories!
But!hippocampus!and!medial!temporal!lobe!is!also!important!for!events!(series!of!events!
needed!to!create!experiences!–!for!spatial!experiences)!
o Medial!temporal!lobe!and!hippocampus:!memories!are!transported!from!sensory!
events!!!conscious!experiences!!!long!term!permanent!memories!
" Faces!and!events!can!lead!to!emotions!
o Parietal!Lobe:!Predicted!Movements!
" Converting!of!hand!and!eye!experiences!into!spatial!memories!
" Prediction!of!where!things!are!going!
" Parietal!lobe!is!the!movement!area!of!the!brain!that!predicts!where!things!are!going!(by!visual!
events,!putting!them!together!in!time!and!space!–!involves!memory!of!where!things!are!going)!
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Retrograde!Amnesia!
Head!injury!(concussion)!!result!in!loss!of!consciousness!!!transient!amnesia.!
Memories!recover!in!reverse!order!(i.e.,!older!memories!first).!
Memories!are!fine!until!you!get!close!to!the!event!
As!you!get!closer!and!closer!to!the!event!–!memories!go!blank!
Amnesia!occurs!for!events!before!the!trauma!and!after!the!trauma!
If!you!go!unconscious,!you!will!not!remember!what!happens!after!(anterograde!amnesia)!
Not!awake,!so!of!course!you!wont!remember!
Memories!come!back!in!the!right!order!(1!hour!before…then!30!minutes!before!the!accident)!
Memories!come!back!in!the!order!that!they!are!restored!
Memories!come!back!in!the!reversed!order:!Older!memories!come!back!first,!then!memories!closer!to!
injury!comes!back!last!
Memories!are!different!as!a!function!of!age!
Older!memories!are!less!vulnerable;!new!memories!most!vulnerable!
As!memories!are!formed,!they!become!less!vulnerable,!and!not!as!easily!disrupted!
New!memories:!come!back!last,!most!damaged,!hardest!to!recover!
New!memories!are!most!vulnerable!to!cortical!disruption!(electroconvulsive!shock!or!concussion).!
Electrocompulsive!shock!–!disrupt!memories!in!the!brain!in!an!organized!way!for!a!second!
Time!of!memory!is!closely!controlled!to!time!of!shock!
Memories!change!(vulnerable!initially,!as!they!mature,!they!become!more!and!more!stable!and!less!
vulnerable!to!injury!!!memories!are!hardening!(consolidation)!
Consolidation!Theory:!Memories!change!from!less!stable!to!more!stable!form.!
Fixed!!!permanent!form!
Hippocampus!converting!memories!from!an!electrical!form!(easily!injured)!into!a!more!stable!form!
(involving!hippocampalKelectricalKchemical!changes,!which!converts!the!memory!over!time!to!a!more!fixed!
more,!eventually!into!a!permanent!form)!
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Anterograde!Amnesia!and!HPC!
Anterograde!amnesia:!unable!to!remember!after!the!trauma,!and!also!sometimes,!inability!to!form!new!memories!
H.M.!has!severe!epileptic!seizures!(temporal!lobe!seizure!that!spreads!from!one!temporal!lobe!to!the!other)!
Removed!medial'temporal'lobe!(included!hippocampus,!entorhinal!cortex!(spatial!memories,!olfactory!
memories),!and!amygdala!AND!areas!coming!into!the!hippocampus)!!!whole!hippocampal!and!
parahippocampal!complex!regions!lost!
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