Biomedical subjects

Patricia A Carpenter

Publications and source records attributed to Patricia A Carpenter.

10 recordsLinked to original sources

PubMed2005

Verbal and spatial working memory in autism.

Verbal and spatial working memory were examined in high-functioning children, adolescents, and adults with autism compared to age and cognitive-matched controls. No deficit was found in verbal working memory in the individuals with autism using an N-back letter task and standardized measures. The distinction between the N-back task and others used previously to infer a working memory deficit in autism is that this task does not involve a complex cognitive demand. Deficits were found in spatial working memory. Understanding the basis for the dissociation between intact verbal working memory and impaired spatial working memory and the breakdown that occurs in verbal working memory as information processing demands are increased will likely provide valuable insights into the neural basis of autism.

Adolescent↗

PubMed2005

Interactions between the dorsal and the ventral pathways in mental rotation: an fMRI study.

In this fMRI study, we examined the relationship between activations in the inferotemporal region (ventral pathway) and the parietal region (dorsal pathway), as well as in the prefrontal cortex (associated with working memory), in a modified mental rotation task. We manipulated figural complexity (simple vs. complex) to affect the figure recognition process (associated with the ventral pathway) and the amount of rotation (0 degrees vs. 90 degrees), typically associated with the dorsal pathway. The pattern of activation not only showed that both streams are affected by both manipulations, but also showed an overadditive interaction. The effect of figural complexity was greater for 90 degrees rotation than for 0 degrees in multiple regions, including the ventral, dorsal, and prefrontal regions. In addition, functional connectivity analyses on the correlations across the time courses of activation between regions of interest showed increased synchronization among multiple brain areas as task demand increased. The results indicate that both the dorsal and the ventral pathways show interactive effects of object and spatial processing, and they suggest that multiple regions interact to perform mental rotation.

Adult↗

PubMed2004

Functional connectivity in an fMRI working memory task in high-functioning autism.

An fMRI study was used to measure the brain activation of a group of adults with high-functioning autism compared to a Full Scale and Verbal IQ and age-matched control group during an n-back working memory task with letters. The behavioral results showed comparable performance, but the fMRI results suggested that the normal controls might use verbal codes to perform the task, while the adults with autism might use visual codes. The control group demonstrated more activation in the left than the right parietal regions, whereas the autism group showed more right lateralized activation in the prefrontal and parietal regions. The autism group also had more activation than the control group in the posterior regions including inferior temporal and occipital regions. The analysis of functional connectivity yielded similar patterns for the two groups with different hemispheric correlations. The temporal profile of the activity in the prefrontal regions was more correlated with the left parietal regions for the control group, whereas it was more correlated with the right parietal regions for the autism group.

Adult↗

PubMed2004

Imagery in sentence comprehension: an fMRI study.

This study examined brain activation while participants read or listened to high-imagery sentences like The number eight when rotated 90 degrees looks like a pair of spectacles or low-imagery sentences, and judged them as true or false. The sentence imagery manipulation affected the activation in regions (particularly, the intraparietal sulcus) that activate in other mental imagery tasks, such as mental rotation. Both the auditory and visual presentation experiments indicated activation of the intraparietal sulcus area in the high-imagery condition, suggesting a common neural substrate for language-evoked imagery that is independent of the input modality. In addition to exhibiting greater activation levels during the processing of high-imagery sentences, the left intraparietal sulcus also showed greater functional connectivity in this condition with other cortical regions, particularly language processing regions, regardless of the input modality. The comprehension of abstract, nonimaginal information in low-imagery sentences was accompanied by additional activation in regions in the left superior and middle temporal areas associated with the retrieval and processing of semantic and world knowledge. In addition to exhibiting greater activation levels during the processing of low-imagery sentences, this left temporal region also revealed greater functional connectivity in this condition with other left hemisphere language processing regions and with prefrontal regions, regardless of the input modality. The findings indicate that sentence comprehension can activate additional cortical regions that process information that is not specifically linguistic but varies with the information content of the sentence (such as visual or abstract information). In particular, the left intraparietal sulcus area appears to be centrally involved in processing the visual imagery that a sentence can evoke, while activating in synchrony with some core language processing regions.

Adolescent↗

PubMed2003

Frontal and parietal participation in problem solving in the Tower of London: fMRI and computational modeling of planning and high-level perception.

This study triangulates executive planning and visuo-spatial reasoning in the context of the Tower of London (TOL) task by using a variety of methodological approaches. These approaches include functional magnetic resonance imaging (fMRI), functional connectivity analysis, individual difference analysis, and computational modeling. A graded fMRI paradigm compared the brain activation during the solution of problems with varying path lengths: easy (1 and 2 moves), moderate (3 and 4 moves) and difficult (5 and 6 moves). There were three central findings regarding the prefrontal cortex: (1) while both the left and right prefrontal cortices were equally involved during the solution of moderate and difficult problems, the activation on the right was differentially attenuated during the solution of the easy problems; (2) the activation observed in the right prefrontal cortex was highly correlated with individual differences in working memory (measured independently by the reading span task); and (3) different patterns of functional connectivity were observed in the left and right prefrontal cortices. Results obtained from the superior parietal region also revealed left/right differences; only the left superior parietal region revealed an effect of difficulty. These fMRI results converged upon two hypotheses: (1) the right prefrontal area may be more involved in the generation of a plan, whereas the left prefrontal area may be more involved in plan execution; and (2) the right superior parietal region is more involved in attention processes while the left homologue is more of a visuo-spatial workspace. A 4CAPS computational model of the cognitive processes and brain activation in the TOL task integrated these hypothesized mechanisms, and provided a reasonably good fit to the observed behavioral and brain activation data. The multiple research approaches presented here converge on a deepening understanding of the combination of perceptual and conceptual processes in this type of visual problem solving.

Adolescent↗

PubMed2003

Brain imaging of tongue-twister sentence comprehension: twisting the tongue and the brain.

This study used fMRI to investigate the neural basis of the tongue-twister effect in a sentence comprehension task. Participants silently read sentences equated for the syntactic structure and the lexical frequency of the constituent words, but differing in the proportion of words that shared similar initial phonemes. The manipulation affected not only the reading times and comprehension performance, but also the amount of activation seen in a number of language-related cortical areas. The effect was not restricted to cortical areas known to be involved in articulatory speech programming or rehearsal processes (the inferior frontal gyrus and anterior insula), but also extended to areas associated with other aspects of language processing (inferior parietal cortex) associated with phonological processing and storage.

Adult↗

PubMed2003

Differential effects of syntactic and semantic processing on the subregions of Broca's area.

This study attempts to specify the contribution of two subregions of Broca's area during syntactic and semantic processing of sentences by examining brain activation in a grammaticality judgment task. The processing of two types of ungrammatical sentences was examined. One type leaves the thematic interpretation generally unaffected, by violating the noun-verb agreement in number, while the other type introduces an extraneous verb, which cannot be incorporated into the developing thematic structure. Pars triangularis was more sensitive to the extra verb violation, whereas pars opercularis was more sensitive to the noun-verb agreement violation. The current study adds to the growing literature that suggests there are separable functional subregions of Broca's area, with pars triangularis more involved in thematic processing and pars opercularis more involved in syntactic processing. The posterior left temporal area was also involved in both types of processing.

Brain Mapping↗

PubMed2003

Ambiguity in the brain: what brain imaging reveals about the processing of syntactically ambiguous sentences.

Two fMRI studies investigated the time course and amplitude of brain activity in language-related areas during the processing of syntactically ambiguous sentences. In Experiment 1, higher levels of activation were found during the reading of unpreferred syntactic structures as well as more complex structures. In Experiments 2A and 2B higher levels of brain activation were found for ambiguous sentences compared with unambiguous sentences matched for syntactic complexity, even when the ambiguities were resolved in favor of the preferred syntactic construction (despite the absence of this difference in previous reading time results). Although results can be reconciled with either serial or parallel models of sentence parsing, they arguably fit better into the parallel framework. Serial models can admittedly be made consistent but only by including a parallel component. The fMRI data indicate the involvement of a parallel component in syntactic parsing that might be either a selection mechanism or a construction of multiple parses.

Adult↗

PubMed2002

The synchronization of the human cortical working memory network.

A verbal reasoning problem at the intersection of verbal working memory, problem-solving, and language comprehension was examined using event-related fMRI to distinguish differences in the differential timing of the response of the various cortical regions that compose the working memory network. Problems were developed such that the process demand as well as the timing of the manipulation of the contents of working memory (i.e., a demanding computation) was varied. Activation was observed in several regions including the dorsolateral prefrontal cortex, the inferior frontal gyrus, and the parietal lobe. Examination of the MR amplitude response revealed that the regions do not all activate simultaneously; instead, their activation time courses reveal differential responses that correspond to their theoretical processing role in the problem-solving task. The coordination of cortical area responses reveals how the various cortical regions synchronize and collaborate in order to accomplish a given cognitive function.

Adult↗

PubMed2002

An fMRI study of bilingual sentence comprehension and workload.

To examine the relation between the cortical substrates that support the comprehension of one's native language and those that support a second language, fMRI measures of cortical activation were taken as native Japanese participants, who had acquired moderate fluency in English, listened to auditory sentences in Japanese and English. In addition, to examine the impact of processing difficulty within a language, sentence difficulty was manipulated by including affirmative (easy) and negative (hard) sentences. The volume of activation was greater for English in most of the cortical regions, suggesting that more cognitive effort was required to process English. Also, a high percentage of the voxels that were activated for the Japanese condition were also activated for the English condition, with as much overlap between Japanese and English as between the processing of affirmative and negative sentences within Japanese. Negative sentences elicited greater activation than affirmative sentences primarily for English, indicating that the structural difficulty of negation has a larger impact on cortical activation if it occurs in the context of the second language, which may serve as another source of difficulty. These results suggest that a shared network of cortical regions supports the processing of both a first and a second language, such that the second language requires more computation and activity from the network.

Adult↗