PubMed Health⌕ Search

Biomedical subjects

Carlo Semenza

Publications and source records attributed to Carlo Semenza.

At least 19 recordsLinked to original sources
PubMed2006

A dedicated neural mechanism for vowel selection: a case of relative vowel deficit sparing the number lexicon.

We report the case of an Italian speaker (GBC), with classical Wernicke's aphasia following a vascular lesion in the posterior middle temporal region. GBC exhibited a selective deficit in spoken language production affecting vowels more than consonants. In reading from a newspaper, GBC substituted vowels for other vowels from the Italian inventory at a rate of 7/1 compared to consonants. No effects of frequency or grammatical class were found. Vowel errors could also not be accounted for by morphological or known phonological processes. Production of number words, in contrast, was free from phonological errors. While GBC has intact representations of Italian vowels and consonants, his data argue for a separate selection mechanism for vowels that is dissociable from that used for consonants. This case provides neuropsychological evidence for models of word production that distinguish between the abstract phonological properties of a word (e.g., sequencing of phonemic slots, or "CV skeleton") and a separate representation for the specific sounds (melody).

Aphasia, Wernicke↗
PubMed2006

Is math lateralised on the same side as language? Right hemisphere aphasia and mathematical abilities.

The main purpose of the present study was to learn how mathematical abilities are located and develop in the brain with respect to language. Mathematical abilities were assessed in six right-handed patients affected by aphasia following a lesion to their non-dominant hemisphere (crossed aphasia) and in two left-handed aphasics with a right-sided lesion. Acalculia, although in different degrees, was found in all cases. The type of acalculia depended on the type of aphasia, following patterns that have been previously observed in the most common aphasias resulting from left hemisphere lesions. No sign of right hemisphere or spatial acalculia (acalculia in left lateralised right-handed subjects) was detected. These results suggest that, as a rule, language and calculation share the same hemisphere. A primitive computational mechanism capable of recursion may be the precursor of both functions.

Aphasia↗
PubMed2006

Acalculia from a right hemisphere lesion dealing with "where" in multiplication procedures.

The present study describes in detail, for the first time, a case of failure with multiplication procedures in a right hemisphere damaged patient (PN). A careful, step-by-step, error analysis made possible to show that an important portion of PN's errors could be better explained as spatial in nature and specifically related to the demands of a multi-digit multiplication. These errors can be distinguished from other types of errors, including those, expected after a right hemisphere lesion, determined by a generic inability to deal with spatial material, or from other deficits, like neglect, affecting cognitive capacities across the board. The best explanation for PN's problems is that he might have difficulties in relying on a visuo-spatial store containing a layout representation specific to multiplication. As a consequence, while knowing what, when and how to carry out the various steps, PN does not know where. What he may thus lack is a spatial schema of multiplication. Such schema is thought to help normal calculators in overcoming working memory demands of complex calculation by representing the information of where exactly each sub-step should be placed.

Adult↗
PubMed2006

How Berlusconi keeps his face: a neuropsychological study in a case of semantic dementia.

A patient (V.Z.) is described as being affected by progressive bilateral atrophy of the mesial temporal lobes resulting in semantic dementia. Vis-a-vis virtually nil recognition of even the most familiar faces (including those of her closest relatives) as well as of objects and animals, V.Z. could nevertheless consistently recognize and name the face of Silvio Berlusconi, the mass media tycoon and current Italian Prime Minister. The experimental investigation led to the conclusion that Mr Berlusconi's face was seen as an icon rather than as a face. This telling effect of Mr Berlusconi's pervasive propaganda constitutes an unprecedented case in the neuropsychological literature.

Aged↗
PubMed2006

Retrieval pathways for common and proper names.

Paradigmatic cases of proper name anomia and proper name selective sparing are reviewed from relevant neuropsychological literature. Available evidence supports the existence of functionally and anatomically distinct retrieval pathways for the categories of proper and common names. An information processing model whose main feature lies in the relative independence within the semantic-conceptual system of information concerning individual entities may account for most of the observed phenomena. Localization studies seem to indicate that a complex neural network sustains various tasks implied in proper name processing. A dedicated module dealing with proper name retrieval is probably there, but its location within the left hemisphere is not at present fully understood. The proper name specific retrieval process is shown, in keeping with current philosophical and linguistic theories, to be intrinsically fragile and source-consuming.

Anomia↗
PubMed2006

Finger-digit compatibility in Arabic numeral processing.

Finger-digit response compatibility was tested by asking participants to identify Arabic digits by pressing 1 of 10 keys with all 10 fingers. The direction of the finger-digit mapping was varied by manipulating the global direction of the hand-digit mapping as well as the direction of the finger-digit mapping within each hand (in each case, from small to large digits, or the reverse). The hypothesis of a left-to-right mental number line predicted that a complete left-to-right mapping should be easier whereas the hypothesis of a representation based on finger counting predicted that a counting-congruent mapping should be easier. The results show that when all 10 fingers are used to answer, a mapping congruent with the prototypical finger-counting strategy reported by the participants leads to better performance than does a mapping congruent with a left-to-right oriented mental number line, both in palm-down and palm-up postures of the hands, and they demonstrate that finger-counting strategies influence the way that numerical information is mentally represented and processed.

Adult↗
PubMed2005

Mental representation of prepositional compounds: evidence from Italian agrammatic patients.

The processing of Prepositional compounds (typical Neo-latin noun--noun modifications where a head noun is modified by a prepositional phrase, e.g., mulino a vento, windmill) was preliminarily studied with a group of six agrammatic aphasic patients, and, in more detail, with a further agrammatic patient (MB). Omission was the most frequent error type in naming, whereas in the other tasks (repetition, reading, writing, and completion) errors were mostly substitutions of the target preposition. This happened even with fully lexicalized compound forms, i.e., those forms where the linking preposition is syntactically and semantically opaque. These findings are interpreted in terms of a dual-route theory of lexical access to morphologically complex words.

Adolescent↗
PubMed2004

Deficient arithmetic fact retrieval--storage or access problem? A case study.

This paper aims at clarifying the nature of fact retrieval difficulties in an 18-year-old young man (MO) who exhibited a puzzling pattern of developmental dyscalculia. Contrasting performance on explicit (production and verification tasks) and implicit (priming) tasks we observed poor overt retrieval of addition and multiplication facts, classical interference effects in verification tasks and inconsistency of error patterns. Hence, MO's performance pattern is suggestive of the existence of a partly stored network of facts (reflecting imperfect storage), but is also compatible with an access deficit according to Warrington and Cipolotti's [Brain 119 (1996) 611] criteria for distinguishing access and storage deficits in dysphasic patients. Furthermore, while MO displayed interference effects in verification tasks, he did not show automatic access to arithmetic facts in implicit tasks. Finally, similar to the findings of Roussel, Fayol, and Barrouillet [European Journal of Cognitive Psychology 14(1) (2002) 61] on normal subjects, MO's performance pattern is suggestive of the existence of differential processing mechanisms for addition and multiplication facts. We propose a unifying mechanism, namely a deficit of the central executive of working memory (WM), that accounts both for the constitution of a fuzzy network of fact representations, and for an access deficit modulated by attentional demands as required in explicit/implicit task paradigms. Overall, our results clearly provide evidence that even in (a developmental) case of a non-perfect network of memory representations (e.g. [Journal of Experimental Psychology: General 117 (1988) 258]), interference effects might be observed. Future studies thus need to be cautious before concluding that interference effects prove the existence of a well-established associative memory network of arithmetic facts.

Adolescent↗
PubMed2004

Inductive reasoning and implicit memory: evidence from intact and impaired memory systems.

In this study, we modified a classic problem solving task, number series completion, in order to explore the contribution of implicit memory to inductive reasoning. Participants were required to complete number series sharing the same underlying algorithm (e.g., +2), differing in both constituent elements (e.g., 2468 versus 57911) and correct answers (e.g., 10 versus 13). In Experiment 1, reliable priming effects emerged, whether primes and targets were separated by four or ten fillers. Experiment 2 provided direct evidence that the observed facilitation arises at central stages of problem solving, namely the identification of the algorithm and its subsequent extrapolation. The observation of analogous priming effects in a severely amnesic patient strongly supports the hypothesis that the facilitation in number series completion was largely determined by implicit memory processes. These findings demonstrate that the influence of implicit processes extends to higher level cognitive domain such as induction reasoning.

Adult↗
PubMed2004

Hemispheric differences in dichaptic scanning of verbal and spatial material by adult males and females.

An experimental design based on the combination of dichaptic presentation associated to the Posner's paradigm was adopted to investigate laterality effects for verbal and spatial non-linguistic stimuli in male and female adult normal subjects. In a grapheme similarity judgment task based on "Name Identity" a right hand/left hemisphere advantage was found. Conversely, laterality effects were neither observed when the task involved "Perceptually Identical" or "Different" letter pairs. In a further experiment, the same methodology was adopted to verify hemispheric effects with spatial non-linguistic material, and a significant advantage for the left hand/right hemisphere was observed. Contrary to many previous studies, no gender or gender x task effects have been detected in both experiments. The present results suggest the existence, also in the tactile domain, of a direct link between input type and the linguistic or non-linguistic processing to which the two hemispheres are devoted. The overall pattern of data seriously hampers Witelson's original hypothesis that letter stimuli presented in the tactile modality are primarily processed as spatial stimuli, and are therefore dependent on the right hemisphere functioning.

Adult↗
PubMed2003

He can tell which master craftsman blew a Venetian vase, but he can not name the Pope: a patient with a selective difficulty in naming faces.

A patient with damage to the left fronto-temporal region could not name faces, although his recognition and semantic knowledge of people were found to be intact. At variance with described anomics for persons' names, this patient was able to retrieve on definition names of people whose faces he could not name. When, instead, objects were to be named with a person's name, as in the case of manufacturers of Murano glass, the patient, a Murano glass master, was perfect. That is, he could tell which master craftsman in the famous Venini glass-works in Venice had blown a vase, but he could not identify the Pope from a picture. Naming faces is therefore shown to be independent of naming objects.

Humans↗
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

Updating and inhibition processes in working memory: a comparison between Alzheimer's type dementia and frontal lobe focal damage.

A large debate has recently focused on the componential nature of the working-memory system (), as evidenced by functional-imaging studies and by using more sophisticated experimental paradigms. The present work aims at further disentangling the role and effects of central executive (CE) and of phonological loop (PL). It is suggested that maintaining active verbal information mostly relates to an intact PL, while the inhibition of interfering information preponderantly involves the CE. To distinguish these effects, two groups of brain damaged patients were administered with an updating task. Frontal lobe patients showed major difficulties in inhibiting interfering information, an ability requiring an involvement of the CE component. In contrast, Alzheimer's dementia patients evidenced a relative impairment in maintaining relevant information, requiring the intervention of the PL.

Adult↗
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↗
PubMed2003

Singing: a selective deficit in the retrieval of musical intervals.

A case of dissociation between discrimination and retrieval of musical information in a patient with a lesion of the right hemisphere is described. This patient has lost the ability to correctly retrieve a musical interval when required to sing. This occurs in the presence of unimpaired interval discrimination and correct retrieval of temporal patterns and melodic contour (direction).

Auditory Perception↗