Forming memories in the brain : Process of consolidation Consolidation : transforms new memories from a fragile state to a more permanent state Levels of reorganization in nervous system : Synaptic consolidation Systems consolidation

Synaptic consolidation Occurs at synapses Happens rapidly Over a period of minutes Discovered molecular processes involved in synthesizing the proteins that result in structural change at the synapse

Systems consolidation Many brain regions Gradual reorganization of cortical circuits Takes place on a longer time scale, lasting weeks, months, or even years Importance of hippocampus in consolidation H.M. lost his ability to form new memories after his hippocampus was removed

Chapter summery 17 Consolidation transforms new memories into a state in which they are more resistant to disruption. Synaptic consolidation occurs at synapses and is rapid. Systems consolidation involves the reorganization of cortical circuits and is slower

H.M. Anterograde amnesia Removal of H.M.’s hippocampus made it impossible for him to form new memories Retrograde amnesia (partially) Amnesia extended back for about 10-15 years prior to his operation He could remember events that occurred before then

Graded amnesia H.M. could remember events from his childhood, but apparently not with as much clarity and detail as a person without brain damage Graded amnesia = amnesia is most severe for events that occurred just prior to the injury and becomes less severe for earlier, more remote events

Forming memories in the brain : Fragility of new memories Graded amnesia (retrograde amnesia) Memory for recent events is more fragile than memory for remote events

Forming memories in the brain : Fragility of new memories Consolidation Transforms new memories from a fragile state, in which they can be disrupted, to a more permanent state, in which they are resistant to disruption A consolidation process must occur before memories become resistant to being disrupted

Hippocampus & consolidation Memory retrieval depends on the hippocampus during consolidation Once consolidation is complete Retrieval no longer depends on the hippocampus Example : Graded amnesia after hippocampectomy

Your memory for last new year’s Eve could include sights, sounds, smells, emotions you were feeling and thoughts you were thinking at the stroke of midnight Experience results in activity of the different cortical areas No connection in the cortex

Standard model of consolidation Incoming information activates a number of areas in the cortex. Activation is distributed across the cortex because memories typically involve many sensory and cognitive areas. Cortex communicates with hippocampus

Reactivation Hippocampus replays the neural activity associated with a memory Results in the formation of connections between the cortical areas

Standard model of consolidation Reactivation process occurs during sleep or during periods of relaxed wakefulness Reactivation process can be enhanced if a consciously rehearses a memory

Standard model of consolidation “ Consolidation occurs during sleep ” Peigneux et al.,2004 Walker & Stickgold, 2004 Finding that memory for learning is enhanced when the learning is immediately followed by a period of sleep

Standard model of consolidation cortical connections become strong enough the different sites in the cortex become directly linked hippocampus is no longer necessary

Standard model of consolidation

Chapter summery 18.1 during consolidation The standard model of consolidation proposes that during consolidation Memory retrieval depends on the hippocampus after consolidation is complete Memory retrieval involves the cortex Hippocampus is no longer involved

Standard model of consolidation Retrieval of recent memories depends on the hippocampus, and cortical connections have not yet formed (a) For retrieval of recent memories, hippocampal activation is high and cortical activation is low

Standard model of consolidation Once consolidation has occurred, cortical connections have formed, and the hippocampus is no longer needed. (b) For retrieval of remote memories, cortical activation is high, and there is no hippocampal activation.

Standard model of consolidation Recent memory : hippocampus & cortex Remote memory : cortex only

Medial temporal lobe & semantic M Recently learned memories cause activity in the MTL MTL do not activated for remote (semantic) memories. Haist 2001 , Wiltgen 2004

Mental time travel (episodic M) & MTL episodic memory Ryan et al.,2001 Participants engage in mental time travel fMRI study activity in hippocampus MTL is activated both when recent episodic memories and remote episodic memories are retrieved

Hippocampus is activated during retrieval of both recent and remote memories

Asaf Gilboa and coworkers 2004 Showing photographs of themselves engaging in various activities that were taken at times ranging from very recently, to when they were 5 years old Results : hippocampus was activated during retrieval of both recent and remote memories.

Moscovitch & Nadel 1997 Experiments that demonstrate MTL and HC activation when retrieving remote episodic memories Support the idea that the hippocampus and MTL are always important when accessing the details of episodic memories

Peter Bayley and coworkers 2005 Describe patients with damage to the MTL who were still able to remember the details of remote episodic memories Results fits the standard model

Standard model of consolidation Support evidence Haist et al.,2001 Wiltgen et al.,2004 Peter Bayley and coworkers 2005 Conflict evidence Ryan et al.,2004 Asaf Gilboa and coworkers,2004 Moscovitch et al.,2005 Nadel & Moscovitch, 1997 Recent memory : hippocampus & cortex Remote memory : cortex only

Chapter summery 18.2 There is evidence supporting the standard model of consolidation, and also evidence supporting the idea that retrieval of episodic memories always involves the hippocampus.

Emotional memory More emotionally events seem to be remembered more easily and vividly than less emotionally events Beginning or ending relationships Arousing words / Neutral words Events experienced by many people simultaneously : tsunami , 9/11 terrorist attack

Memory for emotional stimuli Kevin Lavin and Elizabeth Phelps 1998 Emotionally charged events are easier to remember Tested participants’ ability to recall Arousing words : profanity & sexually explicit words Neutral words : street , store They can recall immediately after they were presented Results : better memory for arousing words

Memory for emotional stimuli Florin Dolcos and coworkers 2005 Tested participants’ ability to recognize emotional and neutral pictures Memory test 1 year after they were initially presented Results : better memory for the emotional pictures

Memory for emotional stimuli (a) Immediately after reading a word (b) 1 years after viewing the pictures

Memory for emotional stimuli Emotional memory / Amydala Brain imaging : fMRI measured by Dolcos Amygdala activity was higher for the emotional words

Memory for emotional stimuli Emotional memory / Amygdala Neuropsychological study : Viewed a slide show about a boy and his mother in which a boy is injured halfway through the show Participants : without brain damage Enhanced memory for emotional part of story B.P. : damaged to amygdala Not enhanced

Memory for emotional stimuli Amygdala Emotion improves memory Emotion enhance the process of consolidation

Chapter summery 19 Memory for emotional stimuli is generally enhanced compared to memory for neutral stimuli. The results of brain scanning and neuropsychological experiments indicate that the amygdala is involved in emotional memory.

How do we retrieve information from LTM ? Retrieval failure occur when the information is “in there” , but we can’t get it out. Most of our failures of memory are failures of retrieval Example : you’ve studied hard for an exam but can’t come up with the answer when you’re taking the exam, only to remember it later when the exam is over.

Retrieval cues Cues that help us remember information stored in our memory Returning to a particular place stimulated memories associated with that place Location can serve as a retrieval cue

Retrieval cues : location While I was in my office at home ,I had made a mental note to be sure to take the DVD on amnesia to school for my cognitive psychology class A short while later, as I was leaving the house, I had a nagging feeling that I was forgetting something, but I couldn’t remember what it was. As soon as I got home, I remembered

Retrieval cues : location Angela’s experience When I was 8 years old, both of my grandparents passed away. Their house was sold, and that chapter of my life was closed. Since then I can remember general things about being there as a child, but not the details. One day I decided to go for a drive. I went to my grandparents’ old house and I pulled around to the alley and parked. As I sat there and stared at the house, the most amazing thing happened. I experienced a vivid recollection. All of a sudden, I was 8 years old again. I could see myself in the backyard, learning to ride a bike for the first time. I could see the inside of the house. I remembered exactly what every detail looked like. I could even remember the distinct smell. So many times I tried to remember these things, but never so vividly did I remember such detail.

Retrieval cues That are provided by returning to the location where memories were initially formed. Hearing the particular song can bring back memories for events you might not thought about for years A musty smell like the stairwell of my grandparents’ house that used to climb

Cued recall Endel Tulving and Zena Pearlstone 1966 Presented participants with a list of words to remember Free-recall group Pigeon, sparrow, chair, dresser, engineer, lawyer Cued-recall group Birds : Pigeon, sparrow Furniture : chair, dresser Professions : engineer, lawyer

Cued recall Endel Tulving and Zena Pearlstone 1966 For the memory test, Participants in the free-recall group were asked to write down as many as possible. Participants in the cued-recall group were also asked to recall the words, but were provided with the names of the categories : birds , furniture, professions

Endel Tulving and Zena Pearlstone 1966

Cued recall Endel Tulving and Zena Pearlstone 1966 Conclusion : the retrieval cues aid memory Free-recall gr. : Recall 40% Cued-recall gr. : Recall 75%

Power of retrieval cues Timo Mantyla 1986 He presented his participants with a list of 600 nouns, such as : banana , freedom , tree During learning, the participants were told to write down three words they associated with each noun Banana : yellow , bunches , edible

Power of retrieval cues Timo Mantyla 1986 When the participants took a surprise memory test, They were presented with the three words they had created and were asked to produce the original word, They were able to remember 90% of the 600 words

Power of retrieval cues Timo Mantyla 1986 Compared to another groups During learning : created cues for “banana”  own cues provided in test During learning : saw “banana” and cues created by someone else  other person’s cues provided in test Didn’t participate in learning  other person’s cues provided in test

Power of retrieval cues Timo Mantyla 1986

Power of retrieval cues Timo Mantyla 1986 Conclusions : Retrieval cues ( the 3 words ) provide extremely effective information for retrieving memories, but that the retrieval cues were more effective when they were created by the person whose memory was being tested

Chapter summery 20 Retrieving LTM is aided by retrieval cues. This has been determined by cues- recall experiments and experiments and experiments in which participants created retrieval cues that later helped them retrieve memories.

Encoding specificity Memory is better when a cue that was associated with an event is reinstated & when the event is to be remembered Encoding Retrieval

Encoding specificity D.R. Godden and Alan Baddeley’s 1975 “diving experiment” On land studying a list of words group Underwater studying a list of words group Each ½ of both groups were tested for recall on land Each ½ of both groups were tested for recall underwater

“diving experiment” The best recall occurred when encoding and retrieval occurred in the same environment

Encoding specificity Harry Grant and coworkers 1998 Studying experiment Participants read an article on psycho immunology while wearing headphones. Silent condition group Noisy condition group Half of each : short-answer test on the article under silent condition Half of each : short-answer test on the article under noisy condition

Studying experiment Participants did better when the testing condition matched the study condition

Chapter summery 21 The principle of encoding specificity states that we learn information along with its context. Godden and Baddeley’s “diving experiment” and Grant’s studying experiment illustrate the effectiveness of encoding and retrieving information under the same conditions

State-Dependent learning Internal state : mood or state of awareness Learning is associated with a particular internal state Principle : memory will be better when a person’s state during retrieval matches his or her internal state during encoding

State-Dependent learning Eric Eich and Janet Metcalfe 1989 Memory is better when a person’s mood during retrieval matches his or her mood during encoding. Asking participants to think positive thoughts while listening to “merry” music or depressing thoughts while listening to “melancholic” music Participants rated their mood while listening

State-Dependent learning Eric Eich and Janet Metcalfe 1989 When mood rating reach “very pleasant” or “very unpleasant” Encoding part of the experiment began Participants studied lists of words while in their positive or negative mood

State-Dependent learning Eric Eich and Janet Metcalfe 1989 After the study session ended Participants were told to return in 2 days The sad group stayed in the lab a little longer Snacking on cookies and chatting with the experimenter while happy music played in the background So they wouldn’t leave the laboratory in a bad mood

State-Dependent learning Eric Eich and Janet Metcalfe 1989 2 days later Participants returned The same procedure was used to put them in a positive or negative mood. When they reach the mood They were given a memory test for the words they had studied 2 days earlier

State-Dependent learning The best recall occurred when encoding and retrieval matched in same mood

Chapter summery 22 According to the principle of state-dependent learning, a person’s memory will be better when his or her internal state during retrieval matches the state during encoding. Eich’ s mood experiment supports this idea.

What memory research tells us about studying ? Ways of improving learning and memory Elaborate and generate Organize Associate Take breaks Match learning and testing conditions

Elaborate and Generate Elaboration The step that transfer the material you are reading into LTM Maintenance rehearsal : read and reread Elaborative rehearsal : better transfer to LTM

Elaborate and Generate Research has shown that students who read a text with the idea of making up questions did as well on an exam as students who read a text with the idea of answering questions later , and both groups did better than a group who did not create or answer questions

Elaborate and Generate Study technique : method of talking out loud Mahya Tavakkoli’ s method My study technique is to talk out loud and explain everything that I know. Sometimes when you read the material, you think “Yeah! I know this!” and move on. But when you get to the exam, you get struck! This is because the material is not in front of you. So by explaining everything out loud, it makes much more sense. It’s a good method to pretend that you’re the professor trying to teach a class of 500 students.

Elaborate and Generate S.W. Peterson 1992 82% of students highlight Most of them do so while they are reading the material for the first time Compared comprehension of both groups  no difference between the performance of both groups when they were tested on the material

Elaborate and Generate Elaborative processing & generation effect Making up question Answering question Recheck correction of the answer to get feedback Mahya ’s method of “pretending you are the professor” Beware of highlighting (automatic behaviour)

Organize Memory is better when the material is organized. Organization creates a framework that helps relate some information to other information Making “trees” Image Chunking makes the material more meaningful Reduce the load on your memory

Associate Elaborative processing is associating what you are learning to what you already know Prior learning creates a structure on which to hang new information Creating imaging that link two things

Take breaks Study in a number of shorter sessions rather than trying to learn everything at once Memory is better when studying the material is broken into a number of short sessions with breaks in between than when studying occurs in one long session

Take breaks The advantage for short study sessions is called Distributed versus massed practice effect It is difficult to maintain close attention to material throughout a long study session Studying after a break gives better feedback about what you actually know. Consolidation is enhanced during sleep

Sleep effect Helps consolidation Restorative effect Improves ability to concentrate and pay attention

Match learning and testing conditions Memory should be better when study (encoding) and testing (retrieval) conditions match as closely as possible. Encoding specificity State-dependence learning

Smith’s result Research has shown that people remember material better when they have learned it in a number of different locations, compared to spending the same amount of time studying in one location

Match learning and testing conditions Making up questions about the material helps encoding Answering the questions, which involves retrieval, not only provides feedback about how well you know the material but helps achieve better encoding as well This strengthened encoding then increases the likelihood that retrieval will be successful

Chapter summery 23 Five memory principles that can be applied to studying are Elaborate and generate Organize Associate Take breaks Match learning and test conditions

Are memories ever Permanent ? Memory is initially fragile, so a disrupting event that occurs shortly after a memory is formed can disrupt formation of memory Once consolidation has occurred, then the same disrupting event cannot affect the memory

Conditioning Conditioning : procedure in which pairing a neutral stimulus with a stimulus that elicits a response causes the neutral stimulus to elicit that response

Conditioning Pavlov’s experiment 1927 He presented a ringing bell ( the neutral stimulus ) to a dog Followed by presentation of food ( which causes the dog to salivate ) This pairing eventually caused the dog to salivate when it heard the bell

Conditioning Stimulus (food)  response (saliva) Stimulus + neutral stimulus (ringing bell)  response Neutral stimulus + …  response

Fear conditioning Stimulus (unpleasant)  response (avoid) Shock  freeze Stimulus (shock) + neutral stimuli (tone)  response (freeze) Neutral stimulus (tone)  response (freeze)

Fear conditioning The rat hears a tone Pairing : tone & shock The rat receives a shock to its foot The shock causes the rat to freeze in place Pairing : tone & shock The rat tested later Neutral tone causes the fear response of freezing

Fear conditioning

Fear conditioning Karim Nader ’s experiments How injection of the chemical anisomycin would affect fear conditioning Anisomycin : ATB that inhibits protein synthesis, which causes the structural changes at the synapse that are responsible for the formation of new memories

Effect on fear conditioning of injecting anisomycin Condition 1 : inject before consolidation Condition 2 : inject after consolidation Condition 3 : inject during reactivation

Figure 6. 34: The effect on fear conditioning of injecting anisomycin Figure 6.34: The effect on fear conditioning of injecting anisomycin. This is based on an experiment by Nader et al. (2000a). See text for details.

1 : Immediate presentation of anisomycin Day1 : inject anisomycin + Initial condition (tone + shock)  fear response in rat (freeze) Anisomycin disrupts protein synthesis before consolidation occur Day3 : tone condition  no rat’s memory for shock-tone pairing  rat does not freeze

2 : Later presentation of anisomycin alone Day1 : shock-tone pairing condition  fear response (freeze)  consolidation : rat learn to fear tone Day2 : inject anisomycin 24 hours after that No disruption of rat’s memory Consolidation has occurred Day3 : tone  rat freeze

3 : Later presentation of anisomycin with the tone Day1 : shock-tone pairing condition  fear response (freeze)  consolidation : rat learn to fear tone Day2 : tone  rat freeze  reactivation + inject anisomycin  eliminates the rat’s memory Day3 : tone  rat has no memory  rat does not freeze

Karim Nader ’s experiments Karim Nader injected the anisomycin under 3 different conditions : Immediate presentation of anisomycin  prevents conditioning Later presentation of anisomycin alone  has no effect (consolidation occurred) Later presentation of anisomycin with the tone  eliminates conditioning

Reconsolidation Learning  consolidation  learning  reactivation : reconsolidation  memory 1 : learning // no consolidation 2 : learning  consolidation  memory 3 : learning  consolidation  learning  reactivation // no reconsolidation  eliminates memory

Updating memory Animal returns to the location of a food source Reactivates the original memory Animal finds that the food has been moved to a new nearby location New information updates the memory Updated memory is then reconsolidation

Updating memory Reconsolidation & reactivation occur when retrieved , provide an opportunity for reinforcing or updating memories Memory becomes to being changed or disrupted every time it is retrieved Memory becomes a more dynamic and adaptable process

Chapter summery 24 Recent research on memory, based largely on fear conditioning in rats, indicates that memories can become susceptible to disruption when they are reactivated by retrieval. After reactivation these memories must be reconsolidated. This process may be a mechanism for refining and updating memories.