Memory Storage

Storage: Retaining Information At the heart of memory is storage. Three stores of memory are shown below: Sensory Memory Working Memory Long-term Memory 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 Sensory Memory Working Memory Long-term Memory 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 & 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? RED The bottom stripe? RED How 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? Right What, if anything, does she have on her feet? Sandals Who is on the front of a $20 bill? Jackson What is on the back? White House Who 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 Changes LTM 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.Tonietal.,Nature,402,Nov Courtesy ofDominiqueMullerBoth Photos:From N.Tonietal.,Nature,402,Nov Courtesy ofDominiqueMuller

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 1 st 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