Transcript STORAGE: RETAINING INFORMATION

STORAGE: RETAINING
INFORMATION
*Fun Facts*
*The current world record for memorizing digits of
pi is held by Chao Lu of China, who memorized
67,890 digits!
*Dominic O’Brien of Great Britain memorized 54
decks of cards, totaling 2,808 cards - a world
record!
*Ben Pridmore of Great Britain, memorized 96
historical dates in 5 minutes. He also set the
world record of memorizing a single shuffled
deck of cards in 26 seconds.
Sensory Memory
• Iconic Memory: a momentary sensory memory of
visual stimuli; a photographic or picture-image
memory lasting no more than a few tenths of a
second; we all have a fleeting photographic memory
*for a few tenths of a second, our eyes register an
exact representation of a scene & we can recall any
part of it in amazing detail…but it clears quickly from
our visual screen as new images are coming in…
• Echoic Memory: a momentary sensory memory of
auditory stimuli; if attention is elsewhere, sounds &
words can still be recalled within 3 or 4 seconds
*ie: attention strays in class to the weekend, teacher
asks “What did I just say?” you can recover the
teacher’s last few words for about 3-4sec.
Working/Short-Term Memory
What are the duration & capacity of short-term
& of long-term memory?
• Short term memory is limited not only in
duration but also in capacity, typically storing
about seven bits of info (+/- 2)
• George Miller (1956) enshrined this recall
capacity as the Magical Number Seven, plus
or minus two
• Both kids & adults have short-term recall for
roughly as many words as they can speak in 2s
* At any given moment, we can consciously
process only a very limited amount of info.
Long-Term Memory
• Even though our capacity for storing long-term
memories is limitless, memory is not a recording of
events.
• Stored memories are interfered with by attention
issues, prior knowledge & memory decay…BUT old
memories are not replaced by new memories!
*Psychologist Rajan Mahadevan could repeat 50
random digits backward; given a block of 10 digits
from the first 30,000 or so digits of pi, Rajan, after a
few moments of mental searching would pick up the
series from there…firing #s like a machine gun.
-He says it is not a genetic gift, anyone could learn to
do it…{his dad memorized Shakespeare’s complete
works!!! }
• http://www.youtube.com/watch?v=Yp9qFSjJZk
• http://www.youtube.com/watch?v=TRD40
Sidevs
How does the brain store our
memories?
• Psychologist Karl Lashley (1950) demonstrated
that memories do not reside in single, specific
locations.
-He trained rats to find way out of maze then
cut out pieces of cortexes & retested their
memory
-No matter which small brain section he
removed, rats retained at least a partial memory
of how to navigate maze
…Storing Memories (cont’d)
• Synaptic Changes:
-Contemporary memory researchers have
searched for a memory trace – the quest to
understand the physical basis of memory – for
how info becomes incarnated in matter – has
sparked study of the synaptic meeting places
where neurons communicate with one another
via their NT messengers.
-We do know that experience modifies brain’s
neural networks; increased activity = new
neural connections forming or strengthened
…cont’d
•
So far…the only evidence to confirm a physical basis for
memory is long-term potentiation (LTP): an increase in a
synapse’s firing potential after brief, rapid stimulation.
-In experiments, rapidly stimulating certain memory-circuit
connections has increased their sensitivity for hours or even
weeks…
*Evidence that LTP is a physical basis for memory:
1. Drugs that block LTP interfere with learning(Lynch & Stabuli,
1991)
2. Mutant mice engineered to lack an enzyme needed
for LTP can’t learn their way out of a maze (Silva et al., 1992)
3. Rats given drug that enhances LTP will learn a maze
with ½ the usual number of mistakes (Service, 1994)
4. Injecting rats with a chemical that blocks the
preservation of LTP erases recent learning (Pastalkova et al.,
2006)
So What?
• Memory-biology explorers have helped to develop &
test memory-boosting drugs; target market =
Alzheimer’s patients, mild cognitive impairment that
becomes Alzheimer’s, and others who’d like to stop
progression of age-related memory loss.
• One approach…developing drugs that boost
production of protein CREB which might lead to
increased production of proteins that help reshape
synapses & consolidate STM into LTM. {sea slugs,
mice & fruit flies w/ enhanced CREB have shown
enhanced memories}
• Another approach…developing drugs that boost
glutamate, a NT that enhances synaptic
communication (LTP).
Stress Hormones & Memory
• When excited/stressed, emotion-triggered
stress hormones make more glucose energy
available to fuel brain activity, signaling the
brain that something important has happened.
• The amygdala (two emotion-processing clusters
in limbic Sx) boosts activity & avail. Proteins in
the brain’s memory forming areas
• Result? Arousal can sear certain events into
brain. “Stronger emotional experiences make
for stronger, more reliable memories)
• Flashbulb Memory: a clear memory of an emotionally
significant moment/event.
-i.e.:first kiss, whereabouts when learning of friend’s
death, 9/11…
-It’s as if your brain says, “Capture this!”
-Usually extremely accurate…unless people relive,
rehearse & discuss the memory & then misinformation
can seep into them.
-Limits to stress-enhanced remembering: when
prolonged (abuse/combat) stress acts corrodes neural
connections & shrinks the hippocampus (vital for
laying down new memories).
-Sudden stress hormones may also block older
memories…mind goes blank when making class
presentation
Ok…now your turn…
Turn to your text pg. 271. Start reading at
Storing Implicit & Explicit Memories &
STOP after you’ve read to the middle of
pg.274.
Take READING NOTES!!!!
{amnesia, H.M., implicit/explicit memory,
hippocampus, cerebellum}