EXAM 3 TEST OBJECTIVES: CIRCUITSThe organization of these ‘test objectives’ is slightly different from what I prepared for Exams 1 and 2. If you can answer these questions, you’ll do well on the test! The Content of Memory: Memory Systems and the Hippocampus (lecture and Chapter 12)1. What is the ‘multiple memory systems’ perspective, and why was the patient ‘H.M.’ important for the realization that memory systems differ by content? a. Multiple memory systems: a theory that different kinds of information are acquired and stored in different parts of the brainb. Some of HM’s memory systems were intact and others were severely damagedi. Had anterograde amnesia: could not acquire some new types of memoriesii. Had short-term but no long-term memoryiii. Disconnect from most of his personal, past experiencesiv. Could learn and remember skill of mirror tracing and rotary pursuit task, but not the training experiences that established skills2. Can you describe the extent of H.M.’s brain damage – what memory systems were spared and which were lost?a. Removal of medial temporal lobesi. Amygdala and hippocampus (entorhinal cortex)ii. Perihinal and parahippocampal cortices were intact3. Who is Brenda Milner? What was her initial diagnosis of H.M.’s memory deficit, and how was this diagnosis updated in later years?a. Milner: HM had severe anterograde amnesiab. Today: removal of temporal lobes disrupted episodic memory system (supports our ability to consciously recollect and report of facts and events we experience)4. Can you describe the extrinsic (inputs, outputs) connectivity of the hippocampus? What does the pattern of inputs and outputs suggest about the function of the hippocampus?a. See 25. Animal Studies: Why was the delayed nonmatching-to-sample (DNMS) task developed? Can you describe the basic DNMS procedure?a. DNMS task developed to determine what brain regions contributed to HM’s memory lossb. Basic DNMS procedurei. Monkey is shown 3D objectii. Later he is presented with a choice between sample and new object (choice component)iii. If monkey chooses new object, he is rewardediv. IMPORTANT1. New objects must be used on each trial2. Experimenter can vary time between sample and choice trial6. What regions of the brain are most critical for correct performance on the DNMS task?a. Damage to rhinal cortex (in medial temporal lobe) impairs performance7. Why are monkeys with damage to just the hippocampus not impaired on the DNMS task? Can you describe the difference between the familiarity-based memory and recollection-based memory?a. These monkeys with hippocampal damage were using the familiarity memory process to make their correct choice and this did not depend on the episodic memory system that supports recollectionb. Familiarity based memoryi. Recognition with recallii. Eg: recognizing a person as familiar without being able to recall information on the place and time you met themc. Recollection based memoryi. Eg: remembering the details about where and when you met personii. Recognition with recallThe Hippocampus Index and Episodic Memory (lecture and Chapter 13)1. What are the basic properties of the episodic memory system?a. Conscious recollection and contextual information storage (conscious)b. Automatic capture of episodic and incidental information (unconscious)c. Single episode capture with protection from interference (unconscious)2. In particular, which properties appear to involve unconscious processes and which involve conscious properties?a. See 1 3. What is pattern completion? What is pattern separation?a. Pattern completion: process by which the memory of an entire experience can be activated or replayed when we encounter a portion of the experience that originally establishes the memory tracei. Possible because synapses on neurons in the hippocampus that represent the patterns of activity in the neocortex have been strengthened and because neurons in the hippocampus project back to the same neocortical regions that project to itii. Most fundamental process provided by the indexb. Pattern separation: process in the hippocampus that keeps representations of similar experiences segregated4. Describe the indexing theory of how the hippocampus supports episodic memory, both in terms of encoding, storage, and retrieval.a. Indexing theory: theory that assumes that the hippocampus stores an index to cortical patterns of neural activity that were generated by an episodei. Relationship with episodic memory1. Conscious recollection and awareness emerge when pattern completion processes activate a representation of the entire event sufficiently to replay memory2. Automatic or incidental storage emerges because synapses that support the memory are automatically strengthened since the experience generates new patterns of neural activity in the neocortex that project on the hippocampus3. Episodic nature of memory due to single experiences, each generating unique patterns of activity on neocortex that is captured by hippocampus4. Interference among similar memories is reduced because hippocampus supports pattern separation 5. What does indexing theory implicitly predict about the locus of conscious experience in the brain?a. The hippocampus automatically captures information that does not have to be consciously recalled to influence behavior6. What problem associated with cortical memory storage is solved by indexing theory?a. Associative connectivity problem: there may not be enough [potential] connections in neurons of neocortex to supportive rapid changes needed to associate patterns of activation across neocortex, but two regions in hippocampus (denate gyrus and CA3) have high internal connectivity and modifiable synapsesb. Interference problem: many of the episodes that make up our daily experiences occur in similar situations. In the neocortex, two similar experiences could be integrated into a common representation.7. What evidence supports the idea that rodents acquire a representation of contexts they explore and that this depends on the hippocampus?a. Context preexposure paradigmi. If rat is placed into cage and shocked immediately, they show little-no fear of conditioned chamberii. If rat is allowed to explore conditioned chamber for a few minutes the day before it receives the shock, it will show substantial fear of chamber1. Demonstrates that rat acquired representation of the context when it explored it during the preexposure phaseb.