2.  Neuroplastic processes related to the ability of the brain to change its functioning in response to experience  Learning ◦ How experience changes the brain  Memory ◦ How the changes are stored & later activated

3.  A patient that had a bilateral medial temporal lobectomy as a treatment for his epilepsy ◦ Removal of the medial portions of both temporal lobes; including most of the hippocampus, amygdala & nearby cortex ◦ Alleviated most of his seizures, but had a significant impact on his memory  Much of our understanding of memory comes from study of this man & the changes to his memory  No one since has had this procedure

5.  Any pathological loss of memory  Retrograde amnesia ◦ Inability to remember information from the past  Anterograde amnesia ◦ Inability to remember new information; can’t form new memories ◦ Short term memory (STM)  Storage of new info for a brief time while a person attends to it ◦ Long term memory (LTM)  Storage of new info once the person stops attending to it

6.  Most of his memory from before the surgery was intact ◦ With the exception of the 2 years prior to the surgery  His short term memory was normal  But it was virtually impossible for him to form new long term memories ◦ As soon as he stopped focusing on new information, he forgot it ◦ He was effectively frozen in time  Global amnesia ◦ Amnesia for memory presented in all sensory modalities

7.  7 tests of his long term memory 1. Digit Span + 1 Test 2. Block-Tapping Memory-Span Test 3. Mirror-Drawing Test 4. Rotary-Pursuit Test 5. Incomplete-Pictures Test 6. Pavlovian Conditioning 7. ???

8. 1. Digit Span + 1 Test ◦ Asked to repeat 5 digits that were read to him, then those 5 + a new digit, etc. ◦ Normal: 15 digits; HM: failure by 8 2. Block-Tapping Memory-Span Test ◦ Asked to tap a series of blocks on a table in the same order the experimenter did ◦ Correct at 5 blocks, incapable of 6

9. 3. Mirror-Drawing Test ◦ Trace a star shape while looking at your hand in a mirror; errors measured ◦ Repeated many times over a few days ◦ His performance improved over time, even though he had no memory of having done the task before

10. 4. Rotary-Pursuit Test ◦ Maintain contact between a stylus and a target on a rotating disc ◦ Again, improvement without him remembering the task 5. Incomplete-Pictures Test ◦ Patient must identify the object in a drawing, with it drawn to different levels of completeness ◦ Again, improvement without him remembering the task 6. Pavlovian Conditioning ◦ Eye-blink task  Tone plays before a puff of air in the eye; eventually the tone alone causes a blink  HM able to learn this, although it took longer than normal

11.  Mild retrograde amnesia ◦ Only 2 years before surgery  Extreme anterograde amnesia ◦ Short term memory was fine ◦ But long term memory was severely impaired  However, tests showed that while he could not consciously remember having done these tasks before, his improved performance on them indicates some type of memory was being formed

12.  Memory functions seem to be highly dependent on the structures of the medial temporal lobe  His differential ability to remember things showed that there were distinctly different types of memory storage ◦ His specific problem seemed to be with memory consolidation, the translation of STM to LTM  Because his performance improved but he couldn’t remember the task, it was determined there are 2 categories of LTM

13. 1. Explicit memories ◦ Things you consciously remember ◦ 2 types 1.Semantic  Memories of general facts or information 2.Episodic  Memories of events in your life (aka autobiographical memories) 2. Implicit memories ◦ Memories that are formed without conscious awareness of them ◦ Indicated by increased performance over time in tasks such as mirror drawing

14.  Korsakoff’s syndrome is a memory disorder common in chronic alcoholics  Brain damage results from thiamine deficiency  Late stages involve sensory & motor problems, extreme confusion, personality changes & potential organ failure  Amnesia similar to that of medial temporal lobe amnesia ◦ Early on, anterograde amnesia for explicit episodic memories is most prominent symptom ◦ Later, severe retrograde amnesia sets in

15.  First symptom of Alzheimer’s is the deterioration of memory  Major anterograde & retrograde deficits in explicit memory  Often have deficits in STM & some types of implicit memory (verbal & perceptual, not sensorimotor)  Acetylcholine depletion may be the cause of amnesia in Alzheimer’s