chapter 12 - learning , memory and intelligence Flashcards
What happens when you have a life without memory ?
Life without memory means no sense of existing across
time.
• Your memory is almost synonymous with your sense of
self
for example, if you lost your ability to to form long-lasting memories. You remember what just happened but nothing earlier. It’s as if you awakened from a long sleep only a second
ago. So you write on a sheet of paper, “Just now, for the first time, I have suddenly become conscious!” A little later, you
forget this experience, too. As far as you can tell, you have just now emerged into consciousness after a long sleeplike period.
You look at this sheet of paper on which you wrote about becoming conscious, but you don’t remember writing it. How odd! You must have written it when in fact you were not con-
scious! Irritated, you cross off that statement and write anew,
“NOW I am for the first time conscious!” And a minute later,
you cross that one off and write it again. Eventually, someone
finds this sheet of paper on which you have repeatedly written and crossed out statements about suddenly feeling conscious
for the first time.
classical conditioning
Pioneered by Ivan Pavlov – Pairing two stimuli changes the response to one of them § Conditioned stimulus Unconditioned stimulus Unconditioned response Conditioned response
book:
stimulus (CS), which initially elicits no
response of note, and then presents the unconditioned stimulus (UCS), which automatically elicits the unconditioned
response (UCR). After some pairings of the CS and the UCS (perhaps just one or two, perhaps many), the individual begins making a new, learned response to the CS, called a conditioned response (CR).
In his original experiments, Pavlov
presented a dog with a sound (CS) followed by meat (UCS),which stimulated the dog to salivate (UCR). After many such pairings, the sound alone (CS) stimulated the dog to salivate(CR). In that case and many others, the CR resembles the UCR, but in some cases, it does not. For example, if a rat ex-
periences a CS paired with shock, the shock elicits screamingand jumping, but the CS elicits a freezing response.
I
instrumental conditioning
instrumental conditioning
– Also known as operant conditioning
– Individual’s response is followed by reinforcer or punishment
– Reinforcers
§ Events that increase the probability that the response will occur again
– Punishment
§ Events that decrease the probability that the response willoccur again
book: For example, when a rat enters one arm of amaze and finds Froot Loops cereal (a potent reinforcer for a rat), its probability of entering that arm again increases. If it
receives a shock instead, the probability decreases.
pic on slide 5
and 6
Pavlov Proposal to Explain Learning
able to map where the condition stimulus, unconditioned response and unconditioned stimulus are in the brain
Engram
Engram = A physical representation of what had been learned
– Example: a connection between two brain areas would be an example of an engram
– Hypothesis: a knife cut between the two brain areas
should abolish the newly learned response
§ Hypothesis disproven
book:
Lashley reasoned that if learning depends on new or
strengthened connections between two brain areas, a knife cut
somewhere in the brain should interrupt that connection and
abolish the learned response.
Lashley experiement for the engram
what are his principles about the n.s
part of engram
Lashley’s experiments showed that learning and memory do not rely on a single cortical area
book:
He trained rats on mazes and
a brightness discrimination task and then made deep cuts in varying locations in their cerebral cortices (Lashley, 1929, 1950)
(Figure 13.3). However, no knife cut significantly impaired the rats’ performances. Evidently, the types of learning that he studied did not depend on connections across the cortex.
ppw:
learning and memory apparently did not rely on a single cortical area.
• Lashley’s principles about the nervous system
– Equipotentiality: all parts of the cortex contribute equally to
complex functioning behaviors (e.g., learning) – Mass action: the cortex works as a whole, and more cortex is better
pic slide 10
Lashley’s Faulty Assumptions
Eventually, researchers discovered that Lashley’s conclusions reflected two unnecessary assumptions:
-The cerebral cortex is the best or only place to search for an engram
• Studying one example of learning is equivalent to studying any other one
The Modern Search for the Engram
his research
Richard F. Thompson and colleagues
– Suggested that the classical conditioning engram is located in the cerebellum, not the cortex
• Lateral interpositus nucleus (LIP) identified as central for learning
– Responses increase as learning proceeds
• However, a change in a brain area does not necessarily mean that learning took place in that area
booK:
Richard F. Thompson and his colleagues used a simpler task than Lashley’s and sought the engram of memory not in the cerebral cortex but in the cerebellum.
Thompson and colleagues studied classical conditioning of eyelid responses in rabbits. They presented first a tone (CS) and then a puff of air (UCS) to the cornea of the rabbit’s eye. At first, a rabbit blinked at the airpuff but not at the tone. After repeated pairings, classical conditioning occurred and the rabbit blinked at the tone also. Investigators recorded the activity in various brain cells to determine which ones changed their responses during learning.
Thompson identified one nucleus of the cerebellum, the lateral interpositus nucleus (LIP), as essential for learning. At the start of training, those cells showed little response
to the tone, but as learning proceeded, their responses increased
If the investigators temporarily suppressed that nucleus of an untrained rabbit, by injecting a drug into it,
and then presented the CSs and UCSs, the rabbit showed no responses during the training. Then they waited for the LIP
to recover and continued training. At that point, the rabbit began to learn, but it learned at the same speed as animals that
had received no previous training. Evidently, while the LIP was suppressed, the training had no effect.
In the next experiments, investigators suppressed activity in the red nucleus, a midbrain motor area that receives input from the cerebellum. When the red nucleus was suppressed, the rabbits again showed no responses during training. However, as soon as the red nucleus had recovered from the cooling or drugs, the rabbits showed strong learned responses to the tone. In other words, suppressing the red nucleus temporarily prevented the response but did
not prevent learning.
Thomson conclusion about the research for engram
Thomson concluded from experiments in rabbits that learning occurred in the LIP
– Later research identified cells and neurotransmitters
responsible for changes in the LIP
• PET scans on young adults led to the discovery that the cerebellum is critical for classical conditioning
– But only if the delay between onset of CS and UCS is short
pic slide 14
book:
According to PET scans on young
adults, when pairing a stimulus with an airpuff produces a conditioned eye blink, activity increases in the cerebellum, red nucleus, and several other areas .
People who have damage in the cerebellum have weaker conditioned eye blinks, and the blinks are less accurately timed relative to the onset of the airpuff
what are the Types of Memory
Hebb (1949) differentiated between two types of memory:
– Short-term memory: memory of events that have just occurred
– Long-term memory: memory of events from times further back
Differences Between Short- and Long-Term Memory (1 of 2)
Short-term memory has a limited capacity, but long-term memory does not
• Short-term memory fades quickly without rehearsal,
while long-term memories persist
• Long-term memories can be stimulated with a cue/ hint
– Short-term memories cannot
researchers propose that all information enter where ?
Researchers propose all information enters short term storage where it stayed until the brain had time to consolidates it into long-term memory
Later research weakened the distinction between short-
and long-term memory
what is weakened /
– Not all rehearsed short-term memories become long-term
memories
– Time needed for consolidation varies
For example, most of the research demonstrating rapid loss of unrehearsed short-term memories dealt with meaningless materials, such as a series of letters or numbers. You hold onto many memories for hours or days without constant rehearsal such as where you plan to meet someone for lunch, where you parked your car, or when is your next dentist’s appointment.
what kind of memory forms quickly ?
and how does it form quickly?
Emotionally significant memories form quickly
– Locus Coeruleus increases release of norepinephrine
– Emotion causes release of epinephrine & cortisol to activate amygdala and hippocampus
—enhances consolidation of recent experiences
working memory
who proposed it ?
what is it ?
Working memory
– Proposed by Baddeley & Hitch as an alternative to shortterm memory
– Emphasis on temporary storage of information to actively
attend to it and work on it for a period of time
book:
to emphasize that temporary storage
is not a station on the route to long-term memory but the way we store information while we are working with it.
working memory - common test for it ?
where does it store the info ?
Common test of working memory is the delayed response task
– Requires responding to something you heard or saw a short while ago
• Research points to the prefrontal cortex for the storage of this information
– Damage impairs performance
– Manner of impairment can be very precise
book:
For example, imagine that a light shines
above one of several doors. The light goes off , you wait a few seconds, and now you have to go to the door where you saw
the light. The delay can be increased or decreased to test your limits. This task can be modified for use with nonhumans as
well as humans. During the delay, the learner has to store a representation of the stimulus, and much research points to the prefrontal cortex as the primary location for this storage
Amnesia
Amnesia is simply defines as memory loss
• Different kinds of brain damage result in different types
of amnesia
what are the Two common types related to amnesia:
• Two common types related to disorders:
– Korsakoff’s syndrome – Alzheimer’s disease
Korsakoff’s Syndrome
Brain damage caused by prolonged thiamine (vitamin
B1) deficiency
– Impedes brain’s ability to metabolize glucose
– Leads to a loss of or shrinkage of neurons in the brain
• Often due to chronic alcoholism
• Distinctive symptom: confabulation (taking guesses to fill in gaps in memory)
– Also apathy, confusion, and memory loss
Alzheimer’s Disease
Associated with a gradually progressive loss of memory,
often occurring in old age
– Affects 50 percent of people over 85 and 5 percent of
people 65–74
– Early onset seems to be influenced by genes
§ 99 percent of cases are late onset
– About half of all patients with late onset have no known
relative with the disease
• No drug is currently effective
check image on slide 23
Alzheimer’s Disease and Proteins
Alzheimer’s disease is associated with an accumulation
and clumping of the following brain proteins:
– Amyloid beta protein
§ Creates plaques from damaged axons and dendrites
§ Produces widespread atrophy of the cerebral cortex,
hippocampus and other areas – An abnormal form of the tau protein
§ Creates tangles § Part of the intracellular support system of neurons
check image 26 and 25
Infant Amnesia
Early childhood amnesia —not a disorder like the
previous two
• Universal experience—we don’t remember much from
our first few years of life
– Children do form memories—the question is why they
forget them
– Hypotheses:
§ Learning language and complex reasoning abilities don’t
develop until the child is older § Changes in the hippocampus and growth of new neuron
The Hippocampus and the Striatum
Different areas of the hippocampus are active during
memory formation and later recall • Damage results in amnesia —and much of what we have
learned about memory has been from patients with
localized brain damage
Memory Loss After Damage to the Hippocampus
Person called H.M. is a famous case study in psychology
– Hippocampus was removed to prevent epileptic seizures
• Afterwards, H.M. had great difficulty forming new long-
term memories
– Short-term/working memory remained intact
• Suggested that the hippocampus is vital for the
formation of new long-term memories
pic slide 30
Anterograde and Retrograde Amnesia
Two major types of amnesia
– Anterograde amnesia: loss of ability to form new memory
after the brain damage
– Retrograde amnesia: loss of memory of events prior to the
occurrence of the brain damage
• H.M. showed both types of amnesia after the surgery
Intact Working Memory
H.M.’s short-term or working memory remained intact
– Was able to remember a number after 15 minutes without distraction
– When distracted, memory was gone in seconds
