Memory - 2

2 types of short-term memory

sensory and working memory

Sensory Memory is

info. from senses automatically stays in the system for a while before disappearing

each senses has its own

memory store (info. from ears is stored separately from info. from nose, eyes, etc)

Sensory Memory last for

a short period (seconds or less)

Sensory Memory is

automatic, all input enters whether you try to remember it or not

There are 2 conditions to the experiment that help explain duration + automatic characteristics of sensory memory

whole report and partial report

whole report is when

Flashes a grid of letters → letters gone → participant needs to recall them → about 35% of letters reported

partial report is when

Flashes a grid of letters → as soon as letters are gone → the experimenter immediately plays a tone indicating which row the participant should recall (got conditioned before) → participants recall → more than 35% of the letters in the row were reported.

the tone act as

a retrieval cue, allowing participants to tap into their sensory memory before it disappeared

the tone help participant direct their attention to

the indicated row of letters in sensory memory (not the screen)

This experiment proves that sensory memory is short cuz

if tone comes too late we can’t use it to search sensory memory for the letter

This experiment proves that sensory memory is automatic cuz

Participants did not know in advance which row they would need to recall. The fact that they could recall almost any cued row when the tone was immediate suggests that they had stored the entire display in memory for a brief moment without consciously selecting or processing specific information (you’re just looking)

Working Memory is

memory of what’s going on right now

Working Memory allows you to

keep in mind your current context

Working memory is a type of

explicit memory (involves conscious recollection)

Working memory lasts much more briefly than

long-term explicit memory

Working memory lasts a bit longer

sensory memory, about a minute

Patient like H.M. (Clive Wearing) also

can’t form new memories but he’s aware of ‘island in time‘ which is the time period stored in his working memory

So for Wearing, as soon as smth leaves his working memory

he forgets about it (can’t form long-term explicit memory)

Capacity of Long-Term Explicit Memory

large (no obvious limit)

Capacity of Working Memory

Small (has limited capacity)

Digit span test

measure how good someone’s working memory is

Digit span test proves that working memory..

has a limited capacity, around 5-9 digits

Relation to behavior of Long-term explicit memory is

weak - info. store here not relate to current behavior

Relation to behavior of Working memory is

Strong - very important for current behavior bc allow you to keep in mind of your current context (if you don’t have this you’ll not know what you’re doing rn)

Most critical Brain Area in Long-term explicit memory is

Medial Temporal lobe, hippocampus (a part of <-)

Most critical Brain Area in Working Memory is

Frontal Cortex

Types of events in the Brain: Long-term explicit memory

Long-term explicit memory is stored in the strengths of synaptic connections

Long-term memories are stored in the strengths of synaptic connections in these networks, regardless

of whether there’s any firing going on rn (about the connection not number of firing of AP)

AP arriving down Neuron A has little impact on the firing of Neuron B →

Synaptic connection weak

AP arriving down Neuron A has large impact on the firing of Neuron B →

Synaptic connection strong

Strength of connections is

critical for long-term memory storage

EX of storing of Long-term explicit memory

A day at the beach

• When you spend a day at the beach, different sensory brain areas process various aspects of the experience (hearing, seeing, and feeling)

• All these sensory experiences are integrated through neural connections, forming a long-term memory of the event.

• Over time, these connections strengthen, allowing the brain to store the experience in long-term memory

• Later, when you recall your day at the beach, the same patterns of neural firing are reactivated in the brain, reconstructing the memory.

if the memory is recalled often,

the connection are further reinforced

The standard model of long-term memory consolidation help explain how

Medial Temporal Lobe (Hippocampus) plays a role in storing long-term memory [cuz we said this brain area is important for long-term mem. ]

The standard model of long-term memory consolidation says that the medial temporal cortex, specifically the hippocampus,

Gradually over time, help strengthen the synapses that form the long-term memory by reactivating the neural network

Events that occur during consolidation: 1) The synaptic connection between

the cortex network (different sensory brain areas process various aspects of the experience) and hippocampus are initially strong

Events that occur during consolidation: 2) As time passes,

The hippocampus makes the same cortical network (the 3 areas) fire AP together repeatedly in the reactivation process (this is when you remember the original event)

Events that occur during consolidation: 3) Over time, synaptic connections between neurons in the

Cortical network (the 3 areas) are formed and become stronger (these strengthened connections are the long-term memory).

Eventually

The connections between the hippocampus and the 3 areas in the cortex are weak and eventually vanish

1st Symptom of H.M. and Clive Wearing: can’t form new memories is called

Anterograde amnesia

The damage to medial temporal lobe destroyed

the ability to consolidate (strengthened) new memories to long-term memories

2nd Symptom of H.M. and Clive Wearing: sometimes have trouble remembering events that happened shorty (3 years) before the lesion often called

Temporally Graded Retrograde Amnesia

Temporally Graded Retrograde Amnesia is when

memory loss is not uniform across all past experience (more recent memories closer to the time of brain damage are more affected than the older memories)

even tho the memory happened before the damage occurred, consolidation

Had not been completed yet (hippocampus has to reactivate the cortical network repeatedly for the memory to become long-term), so the memory was not yet safe without hippocampus