Retrograde Amnesia: Is Memory Gone For Good Or Just Hiding Out? Gretchen Hanson Gotthard, Ph.D. Randolph-Macon Woman’s College Lynchburg, VA

Hypothetical Memory Processes Forgetting Forgetting Amnesia Amnesia EncodingStorageRetrieval

What Causes Amnesia? Transient Agents: Transient Agents:  Electroconvulsive Shock (ECS)  Hypothermia  Hyperthermia  Concussive Head Injury Permanent Agents: Permanent Agents:  Stroke  Brain Tumor  Brain Lesion

Two Types of Amnesia 1. Anterograde Amnesia:  new information  “Memento” and H.M. 2. Retrograde Amnesia:  old information  Trevor Reece Jones Retrograde AmnesiaAnterograde Amnesia

Temporal Gradient of Retrograde Amnesia Normal Memory Normal Memory  Recent better than Remote Amnesia Amnesia  Remote better than Recent

Consolidation Theory Müller and Pilzecker (1900) Müller and Pilzecker (1900)  Storage of information is disrupted.  Permanent loss of memory. EncodingStorageRetrieval X

Evidence for Consolidation Theory Duncan (1949) Duncan (1949)  Passive avoidance  ECS or No ECS (varying delays)  Tested 24 hours later

Results

Retrieval Failure Theory Spear and Riccio (1994) and others… Spear and Riccio (1994) and others…  Retrieval is disrupted  Temporary loss of memory EncodingStorageRetrieval X

Evidence for Retrieval Failure Theory Delayed Onset of Retrograde Amnesia Delayed Onset of Retrograde Amnesia  Geller and Jarvik (1968)  Passive avoidance  ECS or No ECS (immediately after training)  Tested 1, 2, 6, and 24 hours later

Results

More Delayed Onset of Retrograde Amnesia Lynch and Yarnell (1973) Lynch and Yarnell (1973)  Football players  Questioned players immediately and at delays  Experimental Group  Control Group

Results

More Evidence for Retrieval Failure Reminder Treatment Effects Reminder Treatment Effects  Hinderliter, Webster, and Riccio (1975)  Passive avoidance  Hypothermia (immediately after training)  Reminder or no reminder (prior to testing)

Results Hypo/ No Remind Hypo/ Remind No Hypo

How do reminder treatments work? “Two Bump” Theory “Two Bump” Theory  Washington Post Story (early 1990’s)  Levy (1987) State Dependent Retention State Dependent Retention

More Reminder Treatment Effects Hanson, Bunsey, and Riccio (2002) Hanson, Bunsey, and Riccio (2002)  Two odor discriminations (Bunsey Digging Task)

Surgery Lesions to either: Lesions to either: 1. Hippocampal Formation (HF)  Episodic Memory (Events) 2. Parahippocampal Region (PR)  Semantic Memory (Facts) Parahippocampal Region

Hippocampal Formation: Episodic Memory (events)

Parahippocampal Region: Semantic Memory (facts)

Testing Two probe trials (no FL in cups) Two probe trials (no FL in cups) First probe trial: reminder treatment for second probe trial First probe trial: reminder treatment for second probe trial

Results: Latency to Dig

Results: Choice

So Is Memory Gone For Good, Or Just Hiding Out? It’s probably “Just Hiding Out”: It’s probably “Just Hiding Out”:  Consolidation Theory: memories should be immediately and permanently gone However…  Delayed Onset of Amnesia  Reminder Treatment Effects Retrieval Failure Theory provides a better explanation. Retrieval Failure Theory provides a better explanation.

Current Research: Sand Maze Sand Maze: appetitive version of Morris Water Maze Sand Maze: appetitive version of Morris Water Maze Hippocampal Formation: important for spatial learning and memory Hippocampal Formation: important for spatial learning and memory WIN-2 study: synthetic cannabinoids and state dependent retention WIN-2 study: synthetic cannabinoids and state dependent retention  Ashley Smith