NEUR 414 1st Edition Exam 1 Study Guide Chapter 1 5 Neural Systems understanding of memory Henry Gustav Molaison HM around 1950 s he had a bad part of the brain and they wanted to map his brian out and then take out the damaged part surgical removal of bilateral medial temporal lobe Hippocampus surgery did work when talking about seizures wasn t able to form new memories lost memories for about 10 years before surgery normal short term memory interesting party though introduction of a distraction he forgets everything that he just did cannot hold on to memories and convert them to long term memory what was removed hippocampus amygdala entorhinal cortex suffered from retrograde and anterograde amnesia seemed to not be able to form any new memories Mirror tracing task requires for a person to trace in between two lines the only visual cue you have is a mirror reflection of their hand initially everyone would do bad but with more practice normal people would get better HM over time he got better as well excepted on day 1 for him to get better over that day b c of his good short term memory day 2 performance was better day 3 it was even better why was the task so easy for him he had no clue told her that he thought the task was going to be hard but somehow he did well no idea he d done the task before yet was able to perform the task well loss for facts not procedures HUGE Scoville and Milner 1957 paper separated out patients and grouped them into 3 groups no memory defect moderate and severe all medial temporal lobe good portions Two types of declarative memory Semantic memory meanings understandings facts and language Episodic memory memory of autobiographical events Patient K C unable to form any new memories had a shrunken hippocampus could not remember any personal instances in his life could remember general facts but nothing personal about himself episodic memory was gone what causes this Unitary view all memory goes through the hippocampus Separatist view only episodic memories require the hippocampus How are episodic memories stored how is the hippocampus dealing with this episodic memories indexing theory little plates represent where memories are stored little plate represents the hippocampus idea is when you form a memory there are little nodes that get stored in the neocortext and then hippo forms an index spot that joins them together idea is that when you want to remember that memory activates the indexing spot then back activates the memories associated with it idea that hippo is the indexing spot for memory problems didn t seem to make sense with HM they think he lost his entire hippo and shouldn t be able to do this standard model of systems consolidation WRONG builds off of indexing theory if you do things over and over then the nodes become hardwired in the cortex ex learning your name first you needed hippo as a baby to learn your name and then after awhile you knew it and didn t need the hippocampus anymore advantage long term memories eventually become independent of the hippo explanation given to why HM has some memories but not others and studies were done with electrical shock therapy noticed that patients lost recent memories old were more stable must be something different about new memories compared to old think they old are stored somewhere else not in hippocampus problem didn t fit with all human data much more severe memory loss than what was expected didn t fit the animal literature Pattern Completion if you have a small aspect of a memory it will often activate multiple large aspects of the memory where pattern completion thrives Pattern Separation how do you separate the memories form this class from the last class where the index theory breaks down if two memories share nodes then a memory would form in cortex that are joined meaning that both memories are activated and every memory eventually trigged and activated is standard model cannot deal with pattern separation Multiple trace theory memories never become hippo ind multiple index spots are formed and the spots on the cortex overlap every single time you form a memory with these new aspects if forms a new index spot in the hippo the memories that are the most stable would be the memories that have multiple indexing spots associated with them problem memory is finite you would run out of room this theory kind of explains HM 10 years memories that have few to memories that have multiple