Bilateral medial temporal lobe damage does not affect lexical or grammatical processing: Evidence from amnesic patient H.M.

Abstract

In the most extensive investigation to date of language in global amnesia, we acquired data from experimental measures and examined longitudinal data from standardized tests, to determine whether language function was preserved in the amnesic patient H.M. The experimental measures indicated that H.M. performed normally on tests of lexical memory and grammatical function, relative to age- and education-matched control participants. Longitudinal data from four Wechsler subtests (Information, Comprehension, Similarities, and Vocabulary), that H.M. had taken 20 times between 1953 (preoperatively) and 2000, indicated consistent performance across time, and provided no evidence of a lexical memory decrement. We conclude that medial temporal lobe structures are not critical for retention and use of already acquired lexical information or for grammatical processing. They are, however, required for acquisition of lexical information, as evidenced in previous studies revealing H.M.'s profound impairment at learning new words.

Puzzling Thoughts for H. M.: Can New Semantic Information Be Anchored to Old Semantic Memories?

“…On measures of word retrieval, he scored 0.49 -1.65 standard deviations below the means of healthy volunteers, with the exception of the fluency test, on which he scored 2.54 standard deviations below the means of healthy volunteers. This result is consistent with the findings in two other reports (Kensinger et al, 2001;Schmolck, Kensinger, Corkin, & Squire, 2002).…”

“…Following a large bilateral MTL excision, he exhibited massive anterograde amnesia (Scoville, 1954(Scoville, , 1968Scoville, Dunsmore, Liberson, Henry, & Pepe, 1953). He has displayed normal memory for semantic knowledge acquired before 1953 (Kensinger, Ullman, & Corkin, 2001), but he has been profoundly impaired in the acquisition of new semantic knowledge (Gabrieli et al, 1988;Postle & Corkin, 1998).…”

Five down, Absquatulated: Crossword puzzle clues to how the mind works

“…is well known to students of amnesia as a muchstudied individual who had normal memory for events preceding 1953 but severe amnesia for events that occurred after that time (Gabrieli, Cohen, & Corkin, 1988;Kensinger, Ullman, & Corkin, 2001). The cause of the amnesia was surgical resection of medial temporal lobe structures to control otherwise uncontrollable epileptic seizures.…”

Modelling Memory and Learning Consistently from Psychology to Physiology

“…His priming memory was retained (Gabrieli et al 1990). In addition, his ability to access episodic memories for 11 years prior to his surgery was also impaired (Sagar et al 1985), but his semantic memory for word meanings learned in the same 11-year period was retained (Kensinger et al 2001), demonstrating a dissociation between episodic and semantic memory.…”

“…To trigger the recall, subjects are given a word (Robinson 1976) or group of words (Crovitz and Schiffman 1974). Such experiments are often used to measure the past time period for which episodic memory retrieval has been degraded and the degree of degradation (Kensinger et al 2001). 327…”