memory systems Flashcards

Question

hippocampus and the delayed nonmatching task (DNMS)

Answer 1

surgical removal of both amygdala and hippocampus do not result in DNMS deficit will still perform the task well neither structure is directly involved in DNMS memory - instead, subsequent animal and human research showed that damage to the rhinal cortex caused memory impairment for the DNMS

Answer 2

a traditional unitary view of hippocampus function is that all its structures are involved in the production of declarative memories DNMS performance does not rely on episodic memory hippocampus is important for episodic recollection, but the adjacent cortex is important for familiarity

Answer 3

young children with MDL damage after ischemic stroke: - develop normal language and social skills, with fully normal levels of vocabulary and other forms of semantic memory familiarity information does not require episodic context - rats with hippocampal damage still learn to recognize objects, but do not retain information about the learning context

Answer 4

has three properties 1. it supports the conscious recollection of contextual spatiotemporal information for later retrieval - intentional initiation of retrieval-intentional search for a memory - conscious awareness of remembering (a member trace being successfully activated) - does not require either to be active 2. It automatically captures episodic and incidental information about single episodes of our lives - does not require the intention to encode or consolidate the memory - incidental info, no intention, stuff you do not need to know 3. it includes information about the spatial and temporal context that is protected from interference by other memory traces - the stability-plasticity dilemma ie/ can we distinguish between classes or dinner with the same people every night the brain supports episodic memory through a hierarchy and a loop remembering emerges when a retrieved memory trace info about the time, place or context of an experience. Once we remember this it becomes easier to remember things

Answer 5

hippocampus is embedded in neural systems and therefore can interact with other brain regions - has unique intrinsic organization and synaptic connection episodic experiences are first transduced by sense receptors and then processed hierarchially until they reach the hippocampus hippocampus can receive info from many areas because it sits on top uni and polymodal cortical areas support perception processes perirhinal and parahippocampal areas support associative recall entorhinal cortex supports spatiotemporal event context located in medial temporal lobes level of information increases throughout the hierarchy info highly processes before in reaches the hippocampus, becomes amodal ( neurons do not know if people are receiving auditory, visual or somatosensory

Answer 6

hippocampus is insensitive to certain sense ie/ it does not know if it is smell or sound the hippocampal loop supports sequential indexing integrated (amodal) event infromation information is the most compressed and abrstact in the hippocampus anterograde amnesia result from damage to the hippocampus

Answer 7

accounts for three aspects of the relationship between memory and the brain 1. the role of the hippocampus in episodic engram formation (provides map to cortical areas that contain our experiences) has info about pattern activity represented by strengthening of synapses between neocortex and hippocampal neurons and strengthening neurons 2. the nature of the engram 3. the role of the hippocampus in memory retrieval the theory posits that the hippocampus does not store memories, but rather pointers (indices) to memories that are stored in the neocortex assumes individual features that make up a specific episode establish a memory trace by activating patterns of neocortical activity, which then project to the hippocampus

Answer 8

A. the hippocampus and neocortex at rest (sleep?) B. experience represented in cortex is processed through the memory hierarchy C. A subset of the experience (engram) us conjoined with a hippocampal index neuron (s) D. retrieval cues activate the index in the hippocampus. ie/ what you are doing on new years E. the index helps to reactivate the of the stored engram

Answer 9

the index itself has no episodic memory content - the hippocampus is amodal

Answer 10

the ability for the index to restore an entire memory from a single cue activate replay of entire experience. possible because synapses represent patterns in neocortex (has been strengthened) neurons in the neocortex project back to the same hippocampal place that projected to it

Answer 11

a retrieval cue might activate multiple indices, but most activated one will activate only the engram it is associated with memories have overlap - if youenter overlap you are not going to know which engram you entered) - ampount of activation determines which is activated which one gets selected creates different indices from similar patterns cause convergence on different neurons

Answer 12

animal experiments provide a few research advantages - fear conditioning is a simple form of learning that is easily controlled in rodents - systematic damage to brain structures can be performed precisely one observation from fear conditioning studies is that animals who are pre-exposed to a context are more readily fear conditioned to it - context pre exposure facilitation based on immediate shock effect rat placed into locked chamber and shocked within 6 secs later will show no fear to conditioning chamber however if allowed to explore chamber before, it will show fear to that context - rat acquired a representation of the context so not preexposed to a shock

Answer 13

index theory explains the CPFE as resulting from pattern completion of the shock from the context cue if this is true, rat should be fear conditionable to a context they were pre exposed to but no necessarily shocked in it also implies that hippocampal damage will prevents CPFE preexposure created false memory

Answer 14

rats also have preference for exploration of novelty A. when a rat has experience for cubes in context A and cylinder in context B B. they prefer to spend time with the cylinder in context A and the cube in context B rats with hippocampal damage will treat explored objects familiar regardless of context - failure of pattern separation - more readily generalize fear conditioning between contexts rats with hippocampal damage can not remember objects they previously explored keep actively exploring our environments if they have prior exposure to these object then hippocampal damage does not matter because there is a familiarity

Answer 15

A. DOX prevents expression of ChR2 in infused DG neurons B. DOX off rats develop an index for "context A" C. DOX-on (no new ChR2) rats shocked in context B and blue light applied D. Rats tested in context A or C E. Rats with light applied to froze more in context A - false memory success

Answer 16

A. CA1 neurons injected with ArchT (neuron silencer) B. DOX-off rats express ArchT are are fear conditioned C. Application of green light activates ArchT, silencing CA1 neurons D. and inhibiting their fear

Answer 17

production of neurons in the cortex - many distributed cortical neurons are parts of engrams - H2B-GFP TetTag mouse expresses green fluorescent protein when DOX is off A. DOX-on, no GFP expression B. DOX-off, many neurons in the brain express GFP C. DOX-on, retrieval activates c-Fos (immediate early gene) D. Co-expression of GFP and c-Fos reflects engram neurons and were found in many regions optogenically silencing index neurons in CA1 caused a reduction in co-labelled neurons in several cortical areas - therefore, the retrieval memories is influenced by the dynamics of hippocampal index neurons

memory systems Flashcards

(41 cards)