Biomedical subjects

Juliana V Baldo

Publications and source records attributed to Juliana V Baldo.

8 recordsLinked to original sources

PubMed2006

Neural correlates of arithmetic and language comprehension: a common substrate?

There is debate as to the relationship between mathematical ability and language. Some research has suggested that common processes underlie arithmetic and grammar while other research has suggested that these are distinct processes. The current study aimed to address this issue in a large group of 68 left hemisphere stroke patients who were all tested on analogous arithmetic and language comprehension measures. The behavioral data revealed a significant correlation between performance on the comprehension and arithmetic measures, although a subset of patients showed a dissociation in performance on the two tasks. To determine the brain regions critical for performance on each measure, patients' lesions were analyzed using Voxel-based Lesion Symptom Mapping. Arithmetic was associated with a small number of foci, with the most significant region located in the left inferior parietal lobule (Brodmann areas 39 and 40). Comprehension was associated with a larger number of brain regions, most extensively in the left middle and superior temporal gyri. There was also overlap between the arithmetic and comprehension maps in a number of regions, such as the inferior frontal gyrus. Our findings suggest that arithmetic and language comprehension are mediated by partially overlapping brain networks. These findings are discussed in light of previous work on the neural basis of arithmetic ability and its relationship to language.

Adult↗

PubMed2006

Role of frontal versus temporal cortex in verbal fluency as revealed by voxel-based lesion symptom mapping.

Category and letter fluency tasks have been used to demonstrate psychological and neurological dissociations between semantic and phonological aspects of word retrieval. Some previous neuroimaging and lesion studies have suggested that category fluency (semantic-based word retrieval) is mediated primarily by temporal cortex, while letter fluency (letter-based word retrieval) is mediated primarily by frontal cortex. Other studies have suggested that both letter and category fluency are mediated by frontal cortex. We tested these hypotheses using voxel-based lesion symptom mapping (VLSM) in a group of 48 left-hemisphere stroke patients. VLSM maps revealed that category and letter fluency deficits correlate with lesions in temporal and frontal cortices, respectively. Other regions, including parietal cortex, were significantly implicated in both tasks. Our findings are therefore consistent with the hypothesis that temporal cortex subserves word retrieval constrained by semantics, whereas frontal regions are more critical for strategic word retrieval constrained by phonology.

Adult↗

PubMed2006

The role of inferior parietal and inferior frontal cortex in working memory.

Verbal working memory involves two major components: a phonological store that holds auditory-verbal information very briefly and an articulatory rehearsal process that allows that information to be refreshed and thus held longer in short-term memory (A. Baddeley, 1996, 2000; A. Baddeley & G. Hitch, 1974). In the current study, the authors tested two groups of patients who were chosen on the basis of their relatively focal lesions in the inferior parietal (IP) cortex or inferior frontal (IF) cortex. Patients were tested on a series of tasks that have been previously shown to tap phonological storage (span, auditory rhyming, and repetition) and articulatory rehearsal (visual rhyming and a 2-back task). As predicted, IP patients were disproportionately impaired on the span, rhyming, and repetition tasks and thus demonstrated a phonological storage deficit. IF patients, however, did not show impairment on these storage tasks but did exhibit impairment on the visual rhyming task, which requires articulatory rehearsal. These findings lend further support to the working memory model and provide evidence of the roles of IP and IF cortex in separable working memory processes.

Adult↗

PubMed2005

Is problem solving dependent on language?

There has been a long-standing debate in the fields of philosophy and cognitive science surrounding the relationship of language to cognition, but the exact nature of this relationship is still unclear (Sokolov, 1968/1972). In the current study, we explored the role of language in one aspect of cognition, namely problem solving, by administering the Wisconsin Card Sorting Test (WCST) to stroke patients with varying degrees of language impairment (Experiment 1) and to normal participants under conditions of articulatory suppression (Experiment 2). In Experiment 1, there was a significant correlation between performance on the WCST and language measures such as comprehension and naming. Demonstrating the specificity of this result, we also found a significant relationship between language performance and another test of problem solving, the Raven's Colored Progressive Matrices, but no relationship between language and a test of visuospatial functioning. In Experiment 2, normal participants were significantly impaired on the WCST under conditions of articulatory suppression, relative to a baseline condition. Together, these findings suggest that language plays a role in complex problem solving, possibly through covert language processes.

Adult↗

PubMed2004

Is it bigger than a breadbox? Performance of patients with prefrontal lesions on a new executive function test.

Executive deficits of problem solving and concept formation have been associated with frontal lobe dysfunction. Here we describe a new clinical test of concept formation based on the parlor game, Twenty Questions. The Twenty Questions Test requires examinees to ask the fewest number of yes/no questions possible in order to identify a target item from an array of 30 line drawings. The items belong to a number of categories and subcategories that exist in a hierarchical, semantic structure. Patients with focal prefrontal lesions asked significantly more questions than controls in their attempt to guess the target items and sometimes exhausted the 20-question limit. Qualitative analyses revealed that patients tended to use ineffective categorization strategies, for example, relying exclusively on questions that referred to single items. Taken together with previous findings, we conclude that prefrontal cortex supports the on-line organization and conceptualization of category exemplars in concept-formation tasks.

Adult↗

PubMed2002

New semantic and serial clustering indices for the California Verbal Learning Test-Second Edition: background, rationale, and formulae.

The original California Verbal Learning Test (CVLT) employed a semantic clustering index that used the words recalled during a given trial as the baseline for calculating expected values of chance clustering (recall-based expectancy). Although commonly used in cognitive psychology, clustering indices that use recall-based calculations of expectancy are implied by the assumption that organizational processes do not occur until after words are retrieved from memory. This assumption contradicts the generally held assumptions among neuropsychologists that (1) organization is an antecedent to recall, and (2) increases in the use of organizational strategies will result in better recall performance. After reviewing a brief history of clustering metrics, we used Monte Carlo simulations, informative examples, and patient data to examine clustering indices that use the word list as a baseline for calculating expectancy and propose these list-based expectancy measures as a refinement of the clustering indices used on the original CVLT. These indices are used on the recently published CVLT-II.

Cluster Analysis↗

PubMed2002

Memory performance on the California Verbal Learning Test-II: findings from patients with focal frontal lesions.

Numerous studies have suggested that frontal cortex plays a strategic, rather than an absolute, role in memory performance. Typically, frontal patients are reported to have impaired recall but normal recognition memory. A recent meta-analysis, however, has questioned this conclusion. To further investigate the role of frontal cortex in long-term memory, patients with focal frontal lesions and age- and education-matched controls were tested on a new version of the California Verbal Learning Test (CVLT-II). Frontal patients exhibited a number of deficits on this test, including overall poorer recall, an increased tendency to make intrusions, reduced semantic clustering, and impaired yes/no recognition performance. Further analysis of the error rates in the yes/no recognition task revealed that frontal patients were most likely to mistakenly endorse 2 types of distractors: semantically related words and words from an interference list. These findings are discussed with respect to the role of frontal dysfunction in false recollections and poor source memory, as well as the distinction between the roles of frontal and temporal cortex in long-term memory.

Aged↗

PubMed2002

Neuropsychological performance of patients following mold exposure.

UNLABELLED: This study investigated the effects of mold exposure (ME) on human cognition by analyzing neuropsychological data from patients who were exposed to mold in their homes or workplaces. Compared to normative data, ME patients were impaired (<10th percentile) on a number of cognitive measures, with the most consistent deficits in visuospatial learning, visuospatial memory, verbal learning, and psychomotor speed. We also examined emotional functioning and found that a number of ME patients showed evidence of both Axis I and Axis II pathology. Interestingly, there was a significant correlation among patients' scores on the Beck Depression Inventory-Second Edition and the number of neuropsychological tests falling within the impaired range. Given the limited understanding of ME and its effect on the human central nervous system, we provide a working model that attempts to capture the complex interactions of impaired cognition, psychosocial stressors, poor physical health, and emotional functioning in patients following ME. KEYWORDS: mold exposure, mild traumatic brain injury, toxic exposure

Adult↗