Supra‐normal age‐linked retrograde amnesia: Lessons from an older amnesic (H.M.)

Abstract

MacKay and James (2001) demonstrated greater-than-normal retrograde amnesia (RA) for lexical-semantic information in amnesic H.M., a deficit that worsened with aging or represented supranormal age-linked RA (SARA). The present experiments extend these earlier observations to new types of information. Experiment 1 participants (H.M. and carefully matched memory-normal controls) named pictures on the Boston Naming Test and H.M. correctly named reliably fewer pictures with low frequency names, he produced unusual naming errors, and he benefited reliably less than the controls from phonological cues to the target word. Experiment 2 participants recalled irregularly-spelled aspects of familiar words in a two-choice recognition memory task and H.M. chose the correct spelling reliably less often than the controls. Experiment 3 participants read low frequency words aloud at age 73 and H.M. produced reliably more reading errors than the controls. Results of all three experiments indicate supranormal RA (SRA) for information once familiar to H.M. and comparisons with earlier studies using similar or identical stimuli indicated that H.M.'s SRA has worsened with aging from 1980 to 1999. In short, H.M. exhibits SARA for phonological and orthographic information, consistent with the MacKay and James results and with interactions between aging and amnesia predicted under binding theory.

Compensating for Language Deficits in Amnesia II: H.M.’s Spared versus Impaired Encoding Categories

“…The functions and effects of H.M.’s word-, phrase-, and proposition-level free associations were therefore similar: All three (a) enabled H.M. to use his intact retrieval processes to offset his inability to create readily understood phrases and sentences that were novel, coherent, and grammatical (see also [5,11,13,22,24,31,32]) and (b) had undesirable side effects, as the redundancy in “the price of it and price of thing what it is” illustrates (see also [2]).…”

“…produced no more minor retrieval errors involving phrases, words, or phonological units than the controls in Study 2C (see also [20,32]). These results suggest that H.M.’s mechanisms for retrieving and sequencing phrases in sentences, words in phrases, and phonological units in syllables are intact, consistent with (a) his undamaged frontal cortex (see [72]), and (b) extensive evidence indicating that retrieval mechanisms are localized in frontal areas, e.g., Chang et al [73], where extremely localized high gamma (HG, 70–200 Hz) activity in the prefrontal cortex immediately preceded and apparently determined response-related retrieval of specific target phonemes (for additional evidence consistent with a frontal locus for retrieval mechanisms, see [74]).…”

Compensating for Language Deficits in Amnesia I: H.M.’s Spared Retrieval Categories

“…Forming coherent plans for producing novel phrases and sentences has been problematic for H.M. in a wide range of tasks; see, e.g., [3,5,8,9,10,64,65], and [2] (as analyzed in [6]).…”

“…Under this hypothesis, H.M. overused and for three reasons: (a) to compensate for his inability to construct sentence-level plans that were novel, accurate, and grammatical [3,5,6,9,10,11,65,68]; (b) to conjoin familiar propositions into multi-proposition sentences; and (c) to satisfy the instruction to describe TLC pictures using a single grammatical sentence.…”

“…First, such errors are representative rather than exceptional aspects of H.M.’s speech: In well controlled experiments, H.M. has produced: (a) reliably more uncorrected word and phrase omissions than memory-normal controls, as in examples (2)–(4) from MacKay, James, Hadley, and Fogler [3]; (b) reliably more sequencing errors (transpositions, anticipations, and preservations of words and phrases) than memory-normal controls [3], and (c) reliably more neologisms in word reading [4], naming objects on the Boston Naming Test [5] and other tasks [6]. …”