Exam 3 Flashcards
Sensory Memory
milliseconds to seconds
Iconic memory, echoic memory
Short-Term Memory/Working Memory
seconds to minutes
REHERSAL
Long-Term Memory
days to years
not really about a passage of time: when falls below level of consciousness
RETRIEVAL
Global Amnesia
profound forgetfulness
Regardless of modality of information (names, faces, places, odors and music all forgotten)
Regardless of how information is presented (visual, auditory, olfactory)
Amnesiac syndrome: impaired declarative but spared nondeclarative
amnedia tends to spare nondeclarative memory
Retrograde Amnesia
inability to remember prior memories
Anterograde Amnesia
inability to form new memories
Patient H.M.
severe epilepsy; seizures starting at age 15
bilateral removal of MTLs (hippocampus, but posterior hippocampus still present)
William Scoville
Anterograde amnesia – since lesion
Suggests encoding deficit
Retrograde amnesia – prior to lesion
Suggests consolidation deficit
temporally graded retrograde amnesia
Memory consolidation takes time
This is because the neural pathways of newer memories are not as strong as older ones that have been strengthened by years of retrieval and CONSOLIDATION
Episodic Memory
Events (declarative/explicit)
Semantic Memory
Facts (declarative/explicit)
Procedural Memory
Skills (non-declarative/implicit)
Medial Temporal Lobe
Monkeys!!!
Hebbian Learning
“When an Axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased”
- found in hippocampus
- the cellular basis of learning involves strengthening of a synapse that is repeatedly active when the post synaptic neuron fires
- repeated activation causes A’s efficiency, as one of the cells firing B, to increase
- synapses that are active at the same time that the post synaptic neuron fires are strengthened over time
Mechanisms of LTM
Long-term potentiation (LTP)
Hippocampus
NMDA/ AMPA receptors
LTP
long-term potentiation
(LTP) is a persistent strengthening of synapses based on recent patterns of activation
long-term increase in excitability of a neuron to a particular synaptic input caused by repeated high-frequency stimulation to that input
- Repeatedly stimulate a single pathway in hippocampus slices.
- Afterwards, new stimulation caused greater excitatory post-synaptic potential
- This is long-lasting…And Hebb was right!
- It works because of NMDA receptors!
Hippocampus
Hebbian learning/LTP occurs here
Iconic v. Echoic Memory
Unlike visual memory, in which our eyes can scan the stimuli over and over, the auditory stimuli cannot be scanned over and over.
Overall, echoic memories are stored for slightly longer period
While seeing something or touching something is a repeatable and reoccuring event (speaking in terms of short intervals), hearing is a single occuring event. It was probably an evolutionary benefit to keep and process the auditory input better.
last longer than iconic memory because what you have in the basilar membrane vibrating in your cochlea. As a result, it continues to have some kind of sensation and causes action potentials
Types of Memory
Sensory Memory (mil-sec)
Short-Term/W Memory (sec-min)
Long-Term Memory (days-yrs)
Types of Long-Term Memory
Declarative (explicit m)
Non-declarative (implicit m)
Declarative (explicit)
Semantic (facts)
Episodic (events)
Non-Declarative (implicit)
Procedural (motor skills, ex: riding bike)
Perceptual
Classical Conditioning
Nonassociative Learning (habituation sensitization
Perceptual Memory
Perceptual memory, that is the ability to interpret
incoming stimuli by recognizing individuals, by
categorizing them, and by noting relationships
between such individuals and categories, is ubiquitous
among animal species, as is the learning of these
facilities
Animals of all sorts can identify food sources, potential
mates, potential predators, etc. Pigeons have been taught to
categorize using such concepts as tree, fish, and human,
some well outside of their evolutionary background
(Herrnstein 1984). Honey bees have been taught to identify
human letters independently of size, color, position or font
Findings of Brenda Miller
IQ better than pre-op (112)
Fewer seizures
Memory System
See paper
Amnesia Timeline
See paper
H.M. Memory Timeline
See paper
H.M Types of Memory Deficits
DECLARATIVE: lost and impaired
EPISODIC: complete loss (couldn’t remember new people/events)
SEMANTIC: impaired, but some left in tact (rock’n’roll)
NONDECLARATIVE: spared
WORKING: intact
- normal digit span (could count, remember #s, but constant rehersal needed otherwise forgotten upon interruption)
PROCEDURAL MEMORY: intact
- mirror tracing, pursuit rotor tracing, Implicitly familiar w testing equipment, ant amnesiacs can still learn piano pieces
- HM could do priming conceptual task (fish card fill-in)
- Tower of Hanoi (improved, procedural learning, does not remember doing so though)
Temporally Graded Retrograde Amnesia
Memory consolidation takes time!
Occurs because the neural pathways of newer memories are not as strong as older ones that have been strengthened by years of retrieval and CONSOLIDATION
hippocampal memory trace
but cortical reinstatement
Memory in the Brain
Hippocampal activation greater during successful remembering (compared to unsuccessful attempts to remember)
Cortical activity patterns are reinstated in appropriate parts of cortex
Bliss & Lomo
stimulate CA3 –> output measured in CA1
- Repeatedly stimulate a single pathway in hippocampus slices.
- Afterwards, new stimulation caused greater excitatory post-synaptic potential
- This is long-lasting…And Hebb was right!
- It works because of NMDA receptors!
NMDA’s role
- LTP is dependent on NMDA receptors
- Mg=agonist that has block on NMDA receptor
- Opens upon high-frequency stimulation , allowing Ca to flow in; activation of NMDA receptors triggers LTP
Agonist/Antagonist
agonist: molecule that occupies receptor and activates
antagonist: molecule that occupies receptor and blocks
- Mg, AP5
NMDA and AMPA
- Both glutamate receptors
- Binding by glutamate should open channel, but not when Mg in place
- Receptor opens upon high-fq stimulation (Mg block removed, allowing Ca to flow in)
- Ca influx generates series of intracellular chemical cascades
- when these cascades reach the post-synaptic terminal, this activity results in LTP