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Biomedical subjects

D M Corey

Publications and source records attributed to D M Corey.

10 recordsLinked to original sources
PubMed2004

Aberrant auditory processing and atypical planum temporale in developmental stuttering.

OBJECTIVE: To learn if people with persistent developmental stuttering and atypical anatomy of their auditory temporal cortex have, when compared to control subjects, changes in fluency induced with delayed auditory feedback (DAF). BACKGROUND: DAF improves fluency in many individuals who stutter, and induces dysfluency in some normal people. The planum temporale (PT), a portion of auditory temporal cortex, is anatomically atypical in some adults who stutter and atypical anatomy might induce aberrant function. Thus, the people who demonstrate the paradoxical response to DAF might be those who have atypical anatomy. METHODS: Experimental subjects were adults with developmental stuttering (n = 14) and control subjects (n = 14) matched for age, sex, education, and handedness. Volumetric MRI scans of all subjects were obtained and the PT was measured in the right and left hemispheres. Based on these scans, subjects were classified as typical (leftward PT asymmetry) or atypical (rightward PT asymmetry). Prose passages were read at baseline, with non-altered feedback (NAF), and with DAF, and fluency was measured in these three conditions. RESULTS: At baseline the adults with developmental stuttering were significantly more dysfluent than controls (p < 0.0005). Controls' fluency did not significantly change with DAF, but DAF improved fluency in adults with developmental stuttering (p < 0.0005). In the stutter group enhanced fluency was associated with atypical (rightward) PT asymmetry, and the presence of typical (leftward) PT asymmetry was not associated with any significant change in fluency. The individuals with atypical PT asymmetry also had more severe stuttering at baseline compared to the experimental subjects with typical PT anatomy. CONCLUSIONS: In adults with persistent developmental stuttering and atypical PT anatomy, fluency is improved with DAF. These experimental subjects who showed improvement had more severe stuttering at baseline. Anomalous PT anatomy may be a neural risk for developmental stuttering in some individuals. Although a number of explanations are tenable, it may be that atypical rightward PT asymmetry may alter speech feedback, and treatment with DAF might allow these people to compensate.

Adult↗
PubMed2003

Atypical cerebral laterality in adults with persistent developmental stuttering.

BACKGROUND: Two of the most consistent anatomic asymmetries found in the human brain are a larger right than left prefrontal and left than right occipital lobe. Reduced or reversed asymmetries of these regions are considered markers of atypical cerebral laterality, and atypical cerebral laterality has been proposed to increase neural risk for developmental stuttering. OBJECTIVE: S: To learn if atypical prefrontal and occipital lobe asymmetries are more common in adults who stutter vs fluent control subjects and to determine whether lobar size or asymmetry patterns are associated with stuttering severity or language abilities. METHODS: Adults with persistent developmental stuttering (n = 16) and matched control subjects (n = 16) had language and stuttering assessments. Subjects were also studied with volumetric MRI scans. Total hemisphere, prefrontal, and occipital lobe regions were measured, and volumes were calculated proportionally to hemisphere volume. RESULTS: Hemisphere and total brain volumes did not differ between the groups. Control subjects had the expected larger right than left prefrontal and larger left than right occipital lobe volume. In contrast, the adults who stutter did not have these asymmetries. Stuttering severity was not associated with specific anatomic configurations, whereas language-processing deficits in adults who stutter were associated with prefrontal and occipital volume reduction. CONCLUSIONS: Developmental stuttering is associated with atypical prefrontal and occipital lobe asymmetries. In addition, deficits in language processing were associated with some anatomic measures in the adults who stutter.

Adult↗
PubMed2001

Anomalous anatomy of speech-language areas in adults with persistent developmental stuttering.

OBJECTIVE: The major aim of this study was to determine whether adults with persistent developmental stuttering (PDS) have anomalous anatomy in cortical speech-language areas. The major postulate was that anomalous cerebral dominance, reflected by anomalous cortical anatomy in various regions, may put an individual at increased risk for the development of stuttering. METHODS: Adults with PDS (n = 16) and controls (n = 16) matched for age, sex, hand preference, and education were studied. Volumetric MRI scans were completed. Frontal (pars triangularis, pars opercularis) and temporo-parietal areas (planum temporale, posterior ascending ramus) were measured in the left and right hemispheres and interhemispheric asymmetries were computed. Gyral variants were assessed within these perisylvian cortical speech-language areas. RESULTS: The right and left planum temporale were significantly larger in the adults with PDS (p = 0.045), and the magnitude of the planar asymmetry was reduced (p = 0.003). Some gyral variants were unique to the adults with PDS, including a second diagonal sulcus and extra gyri along the superior bank of the sylvian fossa. In addition, anatomic subgroups emerged based on sex and hand preference. Overall, the adults with PDS had significantly more gyral variants (mean = 4.19) than controls (mean = 1.31, p < 0.0005). CONCLUSIONS: These results provide strong evidence that adults with PDS have anomalous anatomy in perisylvian speech and language areas. No one anatomic feature distinguished the groups, but multiple loci within a widely distributed neural network differed between groups. These results provide the first evidence that anatomic anomalies within perisylvian speech-language areas may put an individual at risk for the development of stuttering.

Adult↗
PubMed2001

Dual-task performance in right- and left-handed adults: a finger-tapping and foot-tapping study.

The dual-task paradigm has been used extensively to study laterality, with concurrent verbalization interfering with right finger-tapping in right handers. Only a few studies have used this paradigm to study interference patterns in left handers and have found inconsistent results. The dual-task paradigm has not been used to study interference effects with concurrent verbalization and foot-tapping. The objective of this study was to use this paradigm to assess whether verbal interference produces different effects on finger- and foot-tapping rate for right handers as compared to left handers. 12 right-handed and 12 left-handed men were studied, each with uncrossed hand and foot dominance, i.e., all individuals were either right handed and right footed or left handed and left footed. Subjects performed finger- and foot-tapping tasks with and without verbal interference. A significant relationship was found between handedness and finger- and foot-tapping rate; individuals with a stronger right-hand preference tended to tap at a higher rate on the right side and vice-versa. Analogous relationships were not found when participants were tapping and speaking concurrently. With verbal interference, both right and left handers had a significant asymmetric effect with a decremental response in right finger-tapping rate and a facilitative effect on left finger-tapping rate. In contrast, there was a bilateral decremental response in foot-tapping with verbal interference in both right and left handers. The implications of these findings are discussed with reference to cerebral laterality of language systems and to the differential organization and integration of the motor representations of the hand and the foot.

Adult↗
PubMed2000

Reduced nerve growth factor in Rett syndrome postmortem brain tissue.

To determine whether reduced nerve growth factor (NGF) and/or its high affinity receptor, trkA, play a role in the pathophysiology of Rett syndrome (RS), we used immunohistochemistry in paraffin-embedded human autopsy brain tissue, to quantify NGF and trkA levels within the frontal cortex of 9 RS females and 10 female controls of similar age. The results showed a significant reduction of NGF expression in RS patients (p < 0.001). Specifically, all RS brains exhibited NGF levels at or below the minimum level observed in controls. In 3 RS brains there was no NGF detected. TrkA expression was also reduced in the RS group (p = 0.035). Interestingly, the expression of NGF in the RS group was significantly related to the presence of cortical astrogliosis (r = 0.91) as indicated by immunostaining for glial fibrillary acidic protein (GFAP). This suggests that while the signals for NGF production during injury remain intact, the critical developmental signals required for early NGF production are impaired.

Adult↗
PubMedDate not supplied

Right and left handedness defined: a multivariate approach using hand preference and hand performance measures.

OBJECTIVE: The major aim of this study was to determine whether a combination of hand preference inventories and hand performance measures identifies distinct handedness groups. If distinct groups are identified, then these subgroupings can be used in future studies to learn more about the neurobiology of these distinct handedness groups. BACKGROUND: Although most individuals classify themselves as right- or left-handed, it is not entirely clear whether handedness should be determined based on preference inventories, hand performance tasks, or a combination of these measures. Given that hand preference is linked in part to hemispheric specialization of language, it is important to clearly define hand preference groups if lateralized differences between right- and left-handers are to be explored. Healthy adult right- and left-handers were examined from a multivariate perspective in an attempt to determine whether handedness subgroups exist within performance data. METHOD: Hand preference of 62 right- and left-handed male and female adults was assessed using items from Briggs and Nebes' and Oldfield's handedness inventories. Individuals were assigned to right- and left-hand preference groups, both by visually inspecting the distribution of preference scores and via cluster analysis. Asymmetries in performance of unimanual motor tasks (grooved pegboard, finger-tapping, and grip strength) were then examined using a multivariate approach. RESULTS: Sixteen items from the two-handedness inventories were used to determine preference-based handedness groups. Two non-overlapping groups, right- and left-hand preference, were identified. Writing hand was highly correlated with hand-preference group, as only three individuals in the entire sample wrote with the non-preferred hand. The expected unimodal distributions of performance asymmetry scores, known as laterality quotients (LQs), were seen. However, when those LQs were viewed from a multivariate perspective, distinct performance-based groups emerged. In more than 90% of the observed cases, the performance-based groups corresponded to preference-based groups. No sex differences were found; the relationship between preference and performance measures was not significantly different for men and women. CONCLUSIONS: Writing hand was highly correlated with scores from a hand preference inventory. In contrast, the use of a single hand performance measure, finger tapping or pegboard, did not always correctly classify an individual as right- or left-handed. However, when both of these hand performance measures were used together. individuals were correctly classified as right- or left-handed. Using this approach, two approximately non-overlapping groups, right- and left-handers, emerged. Thus, handedness is probably not a one-dimensional trait or behavior, and must be defined using multiple measures that assess different aspects of hand preference and performance. The implications for hemispheric specialization of language and neural asymmetry research are discussed.

Adult↗