PS4529/30 Applications of Cognitive Neuroscience

1. PS4529/30Applicationsof CognitiveNeuroscience

2. MTL MTL MTL MTL Consensus View of Long-Term Memory ENCODINGRETRIEVAL Seeing Word Hearing Word

3. A Specific Example • The constructive memory framework (CMF) • Schacter, DL, Norman, KA, and Koutstaal, W. (1998). The cognitive neuroscience of constructive memory. Annual Review of Psychology, 49, 289-318. • Invokes multiple brain regions • Some involved in encoding and retrieval • Some involved in either encoding or retrieval • Comprising multiple functions that must interact dynamically with one another

4. CMF Neuroanatomy • The hippocampal formation • ‘Indexing’ of episodes: exactly how is unknown • Necessary both for encoding and retrieval • Damage leads to dense retrograde and anterograde amnesia • The frontal lobes • Strategic control over memory: exactly how is again unknown! • Damage leads to confabulations, delusions, heightened false memory, source amnesia • The entire ‘association’ neocortex • Representation of experienced content • Damage should lead to loss of specific content of prior episodes

5. CMF Retrieval Functions • Retrieval ‘focus’ • Access to the records of attended information via a retrieval cue (by hippocampal pattern completion) • Inhibition of irrelevant information • Re-activation of episodic content (held in the neocortex) • Monitoring/evaluating retrieval products (prefrontally mediated)

7. Conway’s SMS Model The Self Memory System (SMS) has two principle components:- • 1. Autobiographical knowledge base • organised specifically to support our sense of self • 2. The (working) Self • comprises a goal hierarchy, and various other internal mechanisms

8. ‘Self’ Autobiographical Knowledge Base Self-related semantic knowledge Abstracted from specific experiences Episodic Memory tied to specific experiences (e.g. the CMF) Encoding Consolidation Retrieval

9. Take a peek inside yourself… Self Goal Hierarchy Episodic Memory (CMF) Autobiographical Knowledge Base Conceptual Self semantic knowledge Key point: the SMS system is ‘goal-driven’

10. The SMS greatly extends the CMF • Conway: “all daily experiences are destined to be forgotten” • Unless they support longer-term goals • In the short term, accurate memories are vital • Where did I leave my keys • In the long-term, coherence (between goals) is vital • The ‘Husband-Hermit’ or ‘Saint-Sinner’ dilemma

11. SMS Goals • Short term (e.g. daily) • Take the car for a service… • Find the keys… • Post the letter… Overriding principle: accuracy! • Long-term • Get a job • Learn how to drive • Buy a house • Become a solitary religious hermit • Be a loving husband • Overriding principle: coherence Potential for conflict! But: there is an accuracy-coherence trade-off!

12. How is the trade-off achieved? Goal Hierarchy Eat and drink (everyday) Keep warm (everyday) Have a conversation (most days) Watch TV (particular times) Find the car keys (in 5 minutes) Avoid tripping up (when I walk) Post the letter (sometime today) Dentist appointment (this week) Revise (next month) Obtain graduation ball tickets (next few months) Find a less annoying partner (yesterday!) Get a 2:1 (next couple of years) Loose weight (before going on holiday) • The goal hierarchy maintains a stable and coherent set of short and long term goals

13. The SMS: key points • New memories are not formed ‘automatically’ from our experiences • But, experiences are always encoded (e.g. as per the CMF). • An ABM is formed (and retrieved) only when the (working) self interacts with the autobiographical knowledge base • Such interactions are entirely goal-driven • Hence, specific experiences will be forgotten unless they relevant to a goal - within the goal hierarchy • Stable self-image emerges from the coherence imposed by the goal hierarchy, perhaps at the expense of accuracy

14. ‘Self’ Is this: (1) A scientifically acceptable and (2) A forensically useful model? Autobiographical Knowledge Base Self-related semantic knowledge Abstracted from specific experiences Episodic Memory tied to specific experiences (e.g. the CMF) Encoding Consolidation Retrieval

15. Can ERPs reveal exactly what is happening in the brain while people remember their past?

16. Stimuli Time 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 ‘selective attention’ Retrieval Perception/attention Ecphory/inhibition Monitoring Patterncompletion/ Binding cueonset Constructive Memory Framework

17. Time - 0 1 2 3 4 5 6 7 8 9 Focussed Search Retrieve / Inhibit Monitor Stimuli Retrieval failure Retrieval success!!

18. ERP correlates of retrieval from long-term memory

19. Stimuli Time 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 F-N400 Familiarity? Implicit Memory? LP effect Ecphory? RF effect Monitoring? Donaldson, Allan and Wilding (2003) Mecklinger (2000) Rugg and Wilding (2000)

20. Content only (versus failure) Content and Context LP effect magnitude X content relation

21. Using ERPs to investigate the notion of encoding-retrieval overlap1. By manipulating the content of what is encoded and retrieved.2. By manipulating the timing of encoding and retrieval, to make them coincide.

22. 1. Manipulating Content • Operationally define different classes of study episode • Record EEG when instances of each class of episode are recollected • Form ERPs to each class of recollected episode • Contrast the magnitude and topography of ERPs for each class of recollected episode

23. Encoding Retrieval MTL MTL Encoding and Retrieval in vivo… Encoding Retrieval MTL MTL Olfactory (Gottfried et al, 2004) and within ‘sensory domain’ too (Woodruff et al., 2005) TIME Visual Auditory

24. Do ERPs revealmodality specific retrieval processes? • Subjects SAW and HEARD words at study • Performed a word-stem (e.g. MOT__) cued recall task • ERPs were formed to stems completed with • Studied SEEN items • Studied HEARD items • Unstudied NEW items • ERP retrieval effects for each sensory modality:- • SEEN – NEW difference • HEARD – NEW difference Allan, Robb and Rugg (2000), Neuropsychologia, 38 1188-1205.

25. No!ERPs are insensitive todifferences in modality at retrieval Recall visual episode Recall auditory episode As retrieval begins… As retrieval ends…

26. ERP Modality Experiment: Conclusions • Multiple retrieval processes, active at different times • Onset ~ 0.5s after retrieval cue! • Retrieval of ‘visual’ and ‘auditory’ episodes involves common processes. No evidence for modality specific retrieval processes. • ERPs reflect a ‘core component’ of retrieval? • Changes in neocortical activity driven by the Hippocampus during early stages of retrieval (prior to modality specific activations)? • Or: attention to retrieval products?

27. Perceptual Records Perceptual Records Semantic Records Semantic Records Context Context Binding Binding Encoding Storage Retrieval Attentional Control Consolidation Mechanisms Attentional Control Episodic Memory Mechanisms

28. 2. Can we simultaneously encode and retrieve? Gain precise control over the relative timing of events experienced in different modalities. Stress the system by forcing it to handle very rapidly changing inputs, to reveal what the temporal limits are. Examine resulting performance behaviourally And use high temporal resolution neurophysiological data to expose the underlying functional states Allan and Allen (2005), Journal of Neuroscience, 25, 8122-9130.

29. Does encoding temporarily stop when retrieval occurs?

30. 3-Phase Dual-task Paradigm E E E Phase 1 R R Phase 2 E E Phase 3 Key Auditory Visual R R R E == encode (animacy task) +/- 200msec period of stimulus onset asynchrony (SOA) jitter, in 10 time bins (41 – 194msec) R == retrieve (old/new recognition)

31. Stimulus-Onset Asynchrony (SOA) Encode time-line begins controlled ‘jitter’ Time WILD Retrieve time-line begins Expt. 1 SOA range: 50-200msec Expt. 2 SOA range: 50-2000msec

32. Dual-task Performance (Expt. 1)

33. Effect of ‘ignoring’ retrieval cues Retrieval under full attention Retrieval under distracted attention LP effect minimal/absent under DA, replaced by F-N400 but no reliable topographic differences (Allan and Allen, 2005)

34. Conclusions Encoding stabilised at a temporal gap of ~600msec (see Expt. 2), i.e. just as the ERP effect begins. retrieval cue processing is complete. neocortical trace reactivation has commenced. so ‘automatic’ encoding of experience can begin again? Retrieval shows a subtle alteration towards reliance on familiarity Mode-shifting between encoding and retrieval in human memory is relatively sluggish The LP effect may reflect the attention paid to retrieval products, not the representational nature of those products

35. Next week -Do these ERP effects objectively indicate the presence / absence of an episodic memory?