PSY 250 Lecture Notes - Lecture 50: Thiamine, Entorhinal Cortex, Apolipoprotein E
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Chapter 12 Learning and Memory Book Notes
A. Introduction Information
a. Henry Molaison’s life was changed at the age of 7
b. He was knocked down by a bicycle and was unconscious by 5 minutes
c. 3 years later, he started having minor seizures and his 1st major seizure was on his 16th birthday
d. Had a normal life other than 2 year break from high school because made fun of because of his
seizures
e. Was eventually having 10 small seizures a day and at least 1 major seizure a week
f. Medications unable to help, so decided to have an experimental operation
g. A surgeon removed much of both of his temporal lobes, where the seizure activity was originating
h. With medication and the surgery, minor seizures were manageable and major seizures were only 1
a year
i. He moved home and helped his parents and eventually got a job in a rehab facility
j. IQ not affected
k. He was still able to recall personal and public events and remember songs from his earlier life, he
had difficulty learning and retaining new information
B. Learning as the Storage of Memories
a. Without the ability to make a more or less permanent record, you could not learn a skill and
experience would not help shape who you are
b. Amnesia: The Failure of Storage and Retrieval
i. Anterograde Amnesia: an impairment in forming new memories (Henry Molaison’s
symptoms)
ii. Retrograde Amnesia: the inability to remember events prior to impairment (Henry’s
surgery caused this)
iii. HM’s retrograde amnesia extended from the time of the surgery back to the age of 16
1. Had few memories from that period
2. Did not remember the end of WWII or his own graduation
3. When he returned for his 35th high school graduation, he didn’t recognize any
of his classmates
a. It is typical of patients who have brain damage similar to HM’s
iv. HM’s surgery destroyed the hippocampus, hippocampal formation, and amygdala
v. It is impossible to tell (after the surgery) which structures are responsible for the memory
functions that were lost
vi. Hippocampus has many parts that contribute to memory
1. CA1 provides the primary output from the hippocampus to other brain areas;
damage in that part of both hippocampi results in moderate anterograde amnesia
and only minimal retrograde amnesia
2. If damage includes the rest of the hippocampus, anterograde amnesia is severe
3. Damage to the entire hippocampal formation results in retrograde amnesia
extending back 15 years of more
4. More extensive retrograde impairment occurs with broader damage or
deterioration
c. Mechanisms of Consolidation and Retrieval
i. Consolidation: process in which the brain forms a permanent representation of a memory
ii. Retrieval: the process of accessing stored memories
iii. Until your memories are consolidated, they are fragile (can be forgotten)
iv. New memories may be disrupted just by engaging in another activity, and even older
memories are vulnerable to intense experiences such as emotional trauma of
electroconvulsive shock treatment
v. Memory is divided into two stages (short-term and long-term memory)
vi. Hippocampus and prefrontal area are involved during learning and retrieval
d. Where Memories are Stored
i. Hippocampal area is not the permanent storage site for memories
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ii. Hippocampus stores information temporarily in the hippocampal formation; then, over
time, a more permanent memory is consolidated elsewhere in the brain
iii. Short-term memory depends on the hippocampus, and long-term memory requires the
cortex and an interaction over time between the two
iv. We speculated that memories might be stored in the temporal lobes, and more recent
research has supported that idea, with memories for sounds activating auditory areas and
memories for pictures evoking activity in the occipital region
v. All memories are not stored in a single area, nor is each memory distributed throughout
the brain
vi. Different memories are located in different cortical areas
vii. Place Cells: cells in the hippocampus that increase their firing rate when the individual is
in a specific location in the environment
viii. Each cell has a place field, and together these cells form a map of the environment
ix. The fields are dependent on spatial cues in the environment (visual, tactile, and olfactory)
x. Place cells do more than indicate an individual’s current location
xi. fMRI has confirmed that humans have place cells; their activity is so precise that the
investigators could determine the subject’s “location” in a computer-generated virtual
environment
e. Two Kinds of Learning
i. Researchers found that HM could readily learn some kinds of tasks (mirror drawing), but
the next day, he did not remember learning it
ii. Declarative Memory: the memory process that records memories of facts, people, and
events that the person can verbalize, or declare
1. Example: you can remember being in class today, where you sat, who was there,
and what was discussed
2. Includes subtypes
a. Episodic Memory (events)
b. Semantic Memory (facts)
c. Autobiographical Memory (information about oneself)
d. Spatial Memory (location of the individual and of objects in space)
3. Declarative memory is informational (what)
iii. Nondeclarative Memory: nonstatable memories that result from procedural or skills
learning, emotional learning, and simple conditioning
1. Examples
a. Learning mirror tracing
b. Learning how to ride a bicycle
c. Learning how to solve the Tower of Hanoi problem
2. Nondeclarative memory is more concerned with the control of behavior (how)
iv. The main reason to distinguish between the two types of learning is that they have
different origins in the brain, and studying them can tell us something about how the
brain carries out its tasks
v. Amygdala has a significant role in nondeclarative emotional learning
vi. Bechara and his colleagues studied a patient with damage to both amygdalas and another
with damage to both hippocampi
1. Attempted to condition an emotional response in patients by sounding a loud
boat horn when a blue slide was presented but not when the slide was another
color
2. Patient with amygdala damage reacted emotionally to the loud noise, indicated
by increased skin conductance responses and could also tell the researchers
which slide was followed by the loud noise, but blue slide never evoked a skin
conductance increase (conditioning was absent)
3. Patient with hippocampal damage showed an emotional response and
conditioning, but could not tell the researchers which color the sound was paired
with
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4. This neural distinction between declarative learning and nondeclarative
emotional learning may well explain how an emotional experience can have a
long-lasting effect on a person’s behavior even though the person doesn’t
remember the experience
f. Working Memory
i. Brain stores a lot of information, but information just stored is useless
ii. Information must be available
iii. Working Memory: a memory function that provides a temporary “register” form
information while it is being used
1. Holds a phone number you just looked up or that you recall from memory while
you dial the number
2. Holds information retrieved from long-term memory while it is integrated with
other information for use in problem solving and decision making
3. Without this, we couldn’t do long division, plan a chess move, or even carry a
conversation
iv. Has a very limited capacity
v. Prefrontal damage impairs humans’ ability to remember a stimulus during a delay
vi. Prefrontal area plays the major role in working memory
vii. Many researchers believe that the primary role of the prefrontal cortex in learning is as a
central executive
1. Manages certain kinds of behavioral strategies and decision making and
coordinates activity in the brain areas involved in the perception and response
functions of a task, all the while directing the neural traffic in working memory
C. Brain Changes in Learning
a. Learning is a form of neural plasticity that changes behavior by remodeling neural connections
b. Long-Term Potentiation
i. Hebb Rule: principle stating that if an axon of the presynaptic neuron is active while the
postsynaptic neuron is firing, the synapse between them will be strengthened
1. Saw this in action during the development of the nervous system, when synaptic
strengthening helped determine which neurons would survive; some of the
plasticity is retained in the mature individual
ii. Long-Term Potentiation (LTP): an increase in synaptic strength that occurs when
presynaptic neurons and postsynaptic neurons are active simultaneously
1. The best candidate for explaining the neural changes that occur during learning
2. Usually induced in the lab by stimulating the presynaptic neurons with pulses of
high-frequency electricity for a few seconds
3. Temporal summation of these high-frequency stimuli ensures that the
postsynaptic neurons will fire along with the presynaptic neurons
4. Can last for hours in tissue cultures and months in lab animals
5. Studied mostly in hippocampus, but it also occurs in several other areas (visual,
auditory, and motor cortex)
6. Appears to be a characteristic of much of neural tissue (areas most likely to be
involved in learning)
iii. Long-Term Depression (LTD): weakening of a synapse when stimulation of presynaptic
neurons is insufficient to activate the postsynaptic neurons
1. Usually produced by a low-frequency stimulus
2. Believed to be the mechanism the brain uses to modify memories and to clear
old memories to make room for new information
iv. Associative Long-Term Potentiation: strengthening of a weak synapse when it and a
strong synapse on the same postsynaptic neuron are active simultaneously
1. Usually studied in isolated brain tissue with artificially created weak and strong
synapses, but it has important behavioral implications
2. The basis of classical conditioning
c. How LTP Happens
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