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Biomedical subjects

Carlo Semenza

Publications and source records attributed to Carlo Semenza.

8 recordsLinked to original sources
PubMed2003

Verbal free recall in high altitude: proper names vs common names.

Exposure to extreme altitude is known to cause a general impairment of cognitive functions. In this study we investigated the effect of high altitude on the recall of supraspan lists of proper and common names. High altitude seems to have a dramatic effect on the recall of proper names, while common names are more resistant to hypoxia. This effect, however, seems to selectively concern the early items of the lists. This damage to the primacy effect in proper name recall seems permanent over time. The absence of damage in recalling names from the last serial position clearly shows how STM functions are relatively more resistant to the lack of cognitive sources caused by hypoxia.

Adult↗
PubMed2003

Transcoding zeros within complex numerals.

This paper describes a patient (LD) showing a selective syntactic deficit in the production of Arabic numerals. Unlike in previously reported cases, LD's syntactic difficulties result in deletions rather than insertions of zeros, with a reduction of the number magnitude. The pattern of errors highlighted a distinction between "lexical zeros", i.e. the zeros in tens, that are semantically derived, and "syntactic zeros" that are syntactically produced as the result of specific production rules. In LD, only syntactic zeros were affected. Furthermore, the processing of numerals with final zeros was found to be easier than the processing of numerals with internal zeros. This pattern of errors is compatible with the lexical-semantic model of Power and Dal Martello. In this model, in fact, lexical zeros originate from a numerical concept, while syntactic zeros originate from a concatenation operation, plus an overwriting operation leaving one or more intermediary zeros. Thus, lexical zeros may be easier to manipulate than syntactic zeros that merely represent a null quantity associated to a specific power of 10.

Aged↗
PubMed2003

Writing and rewriting arabic numerals: dissociated processing pathways?

The present paper describes two patients, AB and FS, whose deficit in transcoding verbal to Arabic numerals was greatly affected by the format of the input. Despite intact comprehension of written verbal numerals and otherwise intact production of Arabic numerals they both transcode inefficiently the former into the latter. Yet, their ability to write the same Arabic numerals on dictation was fully preserved. Moreover, in both patients' performance, a systematic error pattern emerged reflecting the influence of the lexico-syntactic structure of the input numerals in the transcoding processes. Current models of number transcoding may not easily account for this pattern of dissociation without postulating different code-dependent pathways for verbal to Arabic transcoding. Within a more parsimonious approach, it is tentatively suggested that spoken and written verbal codes activate with different efficiency the same transcoding algorithm.

Adult↗
PubMed2002

Patterns of phonological errors as a function of a phonological versus an articulatory locus of impairment.

We present the case of two aphasic patients: one with fluent speech, MM, and one with dysfluent speech, DB. Both patients make similar proportions of phonological errors in speech production and the errors have similar characteristics. A closer analysis, however, shows a number of differences. DB's phonological errors involve, for the most part, simplifications of syllabic structure; they affect consonants more than vowels; and, among vowels, they show effects of sonority/complexity. This error pattern may reflect articulatory difficulties. MM's errors, instead, show little effect of syllable structure, affect vowels at least as much as consonants and, and affect all different vowels to a similar extent. This pattern is consistent with a more central impairment involving the selection of the right phoneme among competing alternatives. We propose that, at this level, vowel selection may be more difficult than consonant selection because vowels belong to a smaller set of repeatedly activated units.

Aged↗
PubMedDate not supplied

Proper names and noun-to-determiner movement in aphasia: a case study.

Proper names (PN) have properties that are different from those of common names (CN) and as such underlie different syntactic rules. According to one of these rule, in many languages, PN, unlike CN, do not take the determiner. It has been suggested that this happens because PN move themselves from noun position to determiner position. The present study addressed the question of whether noun to determiner movement should be just considered a formal description or rather reflects actual processing. A single aphasia case study and a group study on Alzheimer's patients provide experimental support to the view that movement from nominal to determiner position reflects some psychological computation.

Aged↗
PubMedDate not supplied

Derivation by prefixation in Slovenian: two aphasia case studies.

The present study is concerned with two Slovenian-speaking patients who were asked to produce, in various tasks, verbs, nouns, and adjectives derived by prefixation with prepositions. Despite differences due to their specific linguistic difficulties, both patients' performance was characterized by the differential processing of prefixes and remaining components of complex words. Prepositions in prefixation were mostly preserved, and less frequently substituted, regardless of the numerous errors produced in the remaining portion of the words. These errors seem clearly determined by the morphological structure of the words and therefore appear to be authentic morphological errors. These findings contribute to the theoretical debate on mental lexical representation, speaking in favor of a morphological decomposition in processing of prefixed complex words at different processing levels.

Aphasia, Broca↗
PubMedDate not supplied

Why is "Red Cross" different from "Yellow Cross"?: a neuropsychological study of noun-adjective agreement within Italian compounds.

This study investigates the performance of two Italian nonfluent aphasic patients on noun-adjective agreement in compounds and in noun phrases. A completion, a reading, and a repetition task were administered. Results show that both patients were able to correctly inflect adjectives within compounds, but not in noun phrases. Moreover, they were sensitive to constituent order (noun-adjective vs adjective-noun) within noun phrases, but less so within compounds. These results suggest differential processing for compounds as compared to noun phrases: While the latter require standard morphosyntactic operations that are often impaired in aphasic patients, the former can be accessed as whole words at the lexical level.

Adult↗