Scientific Understanding of Consciousness
Death of H.M.
H.M., a brain surgery patient who had been studied for decades, died 2 Dec 2008 at age 82. These ongoing studies established the distinction between declarative (explicit) memory and procedural (implicit) memory. Henry Gustav Molaison suffered a bicycle accident at age 9 and developed progressively intractable epilepsy, until at age 27 in 1953 he underwent an experimental operation removing his hippocampus on both sides. His epilepsy was relieved, but he could no longer form new declarative memories. He could remember past events and knowledge that had been consolidated prior to his operation. He could form new procedural memories, but he had no declarative memory of his learning experiences in forming the new procedural memories.
H.M.ís amnesia is characterized by: (1) intact perceptual, motor, and cognitive functions, (2) intact immediate memory, (3) severe and global anterograde amnesia, (4) temporally graded retrograde amnesia, (5) spared remote memory. (Howard Eichenbaum, The Cognitive Neuroscience of Memory, 102)
Iíll include a link to my copy of the New York Times H.M. obit.
HMís Science Research Follow-Up
Suzanne Corkin, Ph.D., directs the Behavioral Neuroscience Laboratory in MIT's Department of Brain and Cognitive Sciences. (Corkin; MIT Cognitive Sciences, 161)
Suzanne Corkin studied amnesic patient HM from 1962 through his death on 2 December 2008. (Corkin; MIT Cognitive Sciences, 166)
In 1935 HM was knocked down by a bicycle. His minor seizures began a year later at age 10. His major seizures began at age 16.† His operation occurred at age 27.† Removal was restricted to the medial part of the left and right temporal lobes, including the hippocampus.† The operation did not cure HM's seizure disorder.† His seizures were reduced in frequency, but for the rest of his life he took anticonvulsant medication and had seizures. (Corkin; MIT Cognitive Sciences, 167)
HM's sense-of-self included knowledge of his ancestors, preoperative personal semantic knowledge, memories of his childhood. (Corkin; MIT Cognitive Sciences, 167)
HM from time-to-time had meager conscious recollections of information encountered postoperatively.† For example, he knew he had a memory impairment. (Corkin; MIT Cognitive Sciences, 167)
Link to ó Patient H.M. A Story of Memory
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