Memory Storage

Storage: Retaining Information

At the heart of memory is storage. Three stores of memory are shown below:

SensoryMemory

WorkingMemory

Long-termMemory

Encoding

RetrievalEncoding

Events

Retrieval

This is the “Three box Information

Processing Model”- it shows the 3

stages of information processing w/

the stages of memory intertwined

Long-Term Memory

SensoryMemory

WorkingMemory

Long-termMemory

Encoding

RetrievalEncoding

Events

Retrieval

Long-Term Memory

Unlimited capacity store. Estimates on capacity range from 1000 billion to 1,000,000 billion bits of

information (Landauer, 1986).

The story of Rajan Mahadevan…recited the first 31, 811 digits of pi (the ratio between

the diameter and circumference of a circle)which begins 3.14159 & continues on indefinitely

How well have you encoded/stored information?

Which letters of the alphabet do NOT appear on a “standard” telephone key pad?Q and Z

What is color of the top stripe of the American flag? REDThe bottom stripe? REDHow many red stripes & white stripes does it have? 7 RED 6 WHITE

How many sides does a wooden pencil have?6

How well have you encoded?In what hand does the Statue of Liberty hold her torch?RightWhat, if anything, does she have on her feet?Sandals

Who is on the front of a $20 bill?JacksonWhat is on the back?White HouseWho is on the front of a $5 bill? Back?Lincoln – Lincoln Memorial

Storing Memories in the Brain

1.Wilder Penfield (1967) through electrical stimulation of the brain concluded that old memories were etched in the brain.

2.Loftus and Loftus (1980) reviewed Penfield's data and showed that only a handful of brain stimulated patients reported flashbacks.

3.Lashley (1950) using rats, suggested that even after removing parts of the brain the animals retained partial memory of the maze.

Memory Trace●The search for the engram, the

biological basis of LTM, has taken 2 approaches…

*Looks on the level of synapses and biochemical changes that are believed to represent the physical memory trace in nerve cells

*Looking for neural circuitry used by memory in the brain

Synaptic ChangesLTM forming at the synapse as fragile

chemical traces that gradually consolidate into more permanent synaptic

changes over time(we leave chemical “bread crumbs” in the synapse…more we use, stronger

the memory “trail”)

This explains why a blow to the head or an electric shock to the brain can cause loss of recent

memories that have not yet consolidated.

Both Photos: From N. Toni et al., Nature, 402, Nov. 25 1999. Courtesy of Dominique Muller

Neural Circuitry●Research began by looking at

individuals who had parts of the brain removed in “botched” operations

●H.M. had surgery for epileptic seizures… his hippocampus and amygdala on both sides of the brain were removed

●Since the surgery in 1953, H.M. has been unable to create new memories of the events in his life, although his memories for events prior to the operation remains normal

Brain structures involved in memory

Brain structures●Hippocampus – aids in the initial encoding of

info●Cerebral cortex – memories are changed into

relatively permanent memories●Amygdala – strengthens memories that have

strong emotional associations●These emotional connections act as an aid

for access and retrieval●The amygdala is probably what is

responsible for the persistent and troubling memories associated with PTSD

Where are memories stored?●Memories do not exist in ONE place in the

brain, but reside all over the brain

●It depends upon the nature of the material being learned…information storage appears to be linked to the sites in the brain where the processing of that information occurs

●So if it is visual information, the memory would be stored in the visual cortex…

Stress Hormones & Memory

Heightened emotions (stress related or otherwise)

make for stronger memories…”stress” seems

to boost activity in the brain’s memory-forming

areas.

Continued, lengthy stress can disrupt memory.

Implicit Memories●Memories that you are not

consciously aware of…yet these memories can affect your behavior

●EX: the 1st time you meet someone, you instantly dislike them…implicit memory is at work because they unconsciously remind your of your worst enemy

Explicit Memories●Intentional or conscious

recollection of information…you are deliberately trying to remember something

●EX: when someone asks you about your summer vacation, you consciously attempt to remember

●EX: remembering information when you are taking a test

Procedural Memory●Memory for skills and

habits…most procedural memories are implicit, as you don’t have to think about “how to” after you have learned the info

●EX: walking, riding a bike, driving

Declarative Memory

●Memory for factual information like names, faces, dates, etc…usually are explicit memories and require conscious mental effort

●EX: recalling the directions for driving to a specific location

2 Types of Declarative Memory●Semantic – memory for

language, facts, general knowledge and concepts… the “I know that…” facts (much of what you learn in school)

●Episodic – memory for the biographical details of our individual lives…the “I remember when…” memories

●Stores temporal coding (time tags) to identify WHEN and context coding to indicate WHERE