Browsing by Author "Campbell, Ransom W."
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- Acquired German Accent: A Functional Neural Systems Approach to Foreign Accent SyndromeHarrison, Patti Kelly; Klineburger, Philip C.; Campbell, Ransom W.; Harrison, David W. (2016-01-27)First described by French neurologist Pierre Marie in 1907, foreign accent syndrome (FAS) is a rare speech disorder in which individuals take on, what is perceived by observers, to be a distinct accent differing in many respects from the individual’s native accent. FAS has been of great interest in the neuropsychological literature because its unique features have challenged our understanding of the neural systems underlying the production of speech, shedding light on neural structures that had previously not been regarded as integral to speech production. In the approximately 60 reported cases of FAS, nearly all have involved a stroke or traumatic brain injury resulting in relatively small lesions (in comparison with one resulting in expressive aphasia) of the language dominant hemisphere in the prerolandic motor cortex, insular cortex, the frontal motor association cortex, and/or the striatum of the language dominant hemisphere (Blumstein & Kurowski, 2006). Several FAS cases with neuroimaging data have also shown lesions of the frontoparietal regions, right hemisphere, basal ganglia, and the right cerebellum (Marien, Verhoeven, Engelborghs, Rooker, Pickut, & De Deyn, 2006).
- Dynamic Fluctuations in Emotion and Space Representation: A Functional Cerebral Systems Approach to Right Hemisphere DysfunctionCampbell, Ransom W. (Virginia Tech, 2019-06-07)This study proposed an experimental test of theoretical models related to emotion and space representation in the brain. Previous research has established that emotion is represented, processed, expressed, and regulated largely by the right hemisphere. Furthermore, there is evidence from experimental paradigms and clinical case reports to suggest that the same hemisphere plays a dominant role in the processing of external space. A conceptual difficulty of clinical and neural network overlap arises when right hemisphere disorders of emotion are compared with those of spatial representation. The current experiment tested some of these hypotheses about emotion regulation and spatial representation in the right hemisphere using nonclinical subjects under a cortical stress paradigm designed to mimic the conditions of cortical duress. An additional goal was an extension of a previous study that examined emotional influence on spatial orientation. Results did not support our initial hypotheses. Subsequent analyses did provide some evidentiary support for some theories related to emotion and brain function. Additionally, patterns of subject performance were observed that support traditionally held theories of differential hemispheric function with regard to emotion and spatial behavior. These findings are discussed within the context of theories of emotion, spatial function, and disorders secondary to right hemisphere damage.
- Frontal lobe regulation of blood glucose levels: support for the limited capacity model in hostile violence-prone men.Walters, Robert P.; Harrison, Patti Kelly; Campbell, Ransom W.; Harrison, David W. (2016-12)Hostile men have reliably displayed an exaggerated sympathetic stress response across multiple experimental settings, with cardiovascular reactivity for blood pressure and heart rate concurrent with lateralized right frontal lobe stress (Trajanoski et al., in Diabetes Care 19(12):1412-1415, 1996; see Heilman et al., in J Neurol Neurosurg Psychiatry 38(1):69-72, 1975). The current experiment examined frontal lobe regulatory control of glucose in high and low hostile men with concurrent left frontal lobe (Control Oral Word Association Test [verbal]) or right frontal lobe (Ruff Figural Fluency Test [nonverbal]) stress. A significant interaction was found for Group × Condition, F (1,22) = 4.16, p ≤ .05 with glucose levels (mg/dl) of high hostile men significantly elevated as a function of the right frontal stressor (M = 101.37, SD = 13.75) when compared to the verbal stressor (M = 95.79, SD = 11.20). Glucose levels in the low hostile group remained stable for both types of stress. High hostile men made significantly more errors on the right frontal but not the left frontal stressor (M = 17.18, SD = 19.88) when compared to the low hostile men (M = 5.81, SD = 4.33). These findings support our existing frontal capacity model of hostility (Iribarren et al., in J Am Med Assoc 17(19):2546-2551, 2000; McCrimmon et al., in Physiol Behav 67(1):35-39, 1999; Brunner et al., in Diabetes Care 21(4):585-590, 1998), extending the role of the right frontal lobe to regulatory control over glucose mobilization.
- Frontal lobe regulatory control mechanisms: Evidence for diminished frontal eye field capacity in hostile violence-prone men.Harrison, Patti Kelly; Campbell, Ransom W.; Smith, Andrew J.; Mitchell, Gina A.; Walters, Robert P.; Harrison, David W. (2016-02-03)Background: The experiment was designed to test the relationship between self-reported hostility and the capacity of frontal eye field regulatory control over visual smooth pursuit eye movements. Previous research has demonstrated a relationship between hostility, violence-prone aggression, and poorly regulated sympathetic control including traditional measures of cardiovascular risk. Capacity Theory (see Harrison, 2015) specifically predicts diminished reflex regulation, dystonia, or spasticity with conditions which exceed the capacity of the frontal systems involved in the response. For visual smooth pursuit eye movements, the frontal eye fields regulate/inhibit ipsilateral visuomotor reflexes under directional control of the superior colliculi and pontine region. Moreover, directional eye movements reflecting intentional direction of visual smooth pursuit derive from premotor regions at each dorsolateral frontal eye field and with directional intent toward the contralateral hemispace (e.g., right frontal eye field directs intentional eye movements toward the left hemispace and inhibits saccadic movements toward the right hemispace). Material/Methods: We tested a total number of 48 college-age men evenly divided between two groups, twenty-four low-hostiles and twenty-four high-hostiles. All subjects were acquired from the undergraduate Psychology pool and the project was approved by the Human Subjects Committee and the Institutional Review Board. In order to continue in the experiment, subjects had to have scored within either the low (0-19) or high (29-50) range of self-reported hostility onthe Cook-Medley Hostility Scale (CMHS). Due to their relatively heightened cerebral lateralization, only men were used to ensure as much homogeneity as possible within the experiment, so as to draw conclusions based solely on independent variable differences. Hostile men were compared with low hostile men using the electrooculogram (EOG). Smooth pursuit errors were identified in the EOG record as phasic errors in the analogue record. Results: Hostile men produced significantly more smooth pursuit irregularities in comparison with low hostiles, consistent with the predictions of Capacity Theory, supporting the contention of diminished frontal eye field integrity in hostile, violence-prone men. Conclusions: These findings sit collectively among a systematic line of research with accumulating evidence implicating capacity limitations for frontal lobe regulatory control in hostile, violence-prone individuals. The broader research implication is suggestive for remediation and preventative techniques for the amelioration of confrontative and/or coercive stress using these brain systems. Moreover, the theory specifically is predictive of heightened sensitivity for the sensory and emotional analyzers residing at the other end of the longitudinal tracts and within posterior brain regions. Emotional sensitivity reflecting coercive threat analysis, feelings of external control by others, and sensitivity to the emotional array presented by others’ facial expressions, tone of voice, and by innuendo may ultimately be a social disability. This effect may be propagated further in any social interaction where others may evaluate the hostile, violence-prone individual as insensitive and callous, perhaps.
- Hallucinations and hemispatial neglect following right middle cerebral artery cerebrovascular accident: Left gaze bias with left sensory hemineglect syndromeHarrison, David H.; DeVore, Benjamin B.; Campbell, Ransom W.; Harrison, Patti Kelly (2017-12-12)Lesions within the right middle cerebral artery distribution commonly result in one or another variant of left hemineglect syndrome with sensory or attention deficits derived from damage within the posterior branches serving occipital, temporal, and parietal brain regions. Motor or intentional deficits within left hemispace have been commonly derived from damage within the anterior branches of the right middle cerebral artery.
- Spreading activation in emotional memory networks and the cumulative effect of somatic markers.Foster, Paul S.; Hubbard, Tyler; Campbell, Ransom W.; Poole, Jonathan; Pridmore, Michael; Bell, Chris; Harrison, David W. (2016-07-15)
- Spreading activation in emotional memory networks and the cumulative effect of somatic markers.Foster, Paul S.; Hubbard, Tyler; Campbell, Ransom W.; Poole, Jonathan; Pridmore, Michael; Bell, Chris; Harrison, David W. (2016-07-15)