No description available.

Participants with Down syndrome (DS) as well as typically developing peers matched for mental and chronological age completed a 3-step movement sequence in response to visual (lights), verbal (spoken word), meaningful auditory (music), and non-meaningful auditory (tones) instructions. Results indicate that participants with DS demonstrated slower reaction time in the visual condition but were more consistent in their movement time and made fewer errors suggesting they adopted a strategy in which they traded speed for accuracy. Further, they were slowest, most variable, and made the most errors in the non-meaningful auditory condition indicating that the amount of meaning associated with the method of instruction is an important determinant of motor performance. These results support the assertion that motor performance for persons with DS is determined in part by the unique pattern of cerebral lateralization for this population while at the same time demonstrating the importance of task and stimulus familiarity.

The influence of levels of hostility on the lateralized tasks of verbal and nonverbal fluency, and the concurrent cerebral regulation of autonomic nervous system functioning was examined. Forty-eight right-handed males were recruited for participation with half classified as low-hostile and the other half as high-hostile. Previous research has shown that high-hostile males, at rest, have greater right hemisphere arousal relative to low-hostile males. It was predicted that this heightened, at rest, arousal would lead to reduced capacity to perform right hemisphere lateralized proximal tasks simultaneously. Two commonly used neuropsychological tests sensitive to left and right anterior cerebral systems are the Controlled Oral Word Association Test and the Ruff Figural Fluency Test (RFFT) respectively. Nonverbal fluency, verbal fluency, and perseverative errors were assessed using these measures. Cardiovascular measures of systolic and diastolic blood pressure, and heart rate were assessed using oscillometric technique with a digital blood pressure meter. A dual-task methodology was used to evaluate these anterior and posterior cerebral systems simultaneously. Since cardiovascular regulation and nonverbal fluency are both right-frontal tasks, it was predicted that high hostile men would evidence increased interference on cardiovascular regulation concurrent with the nonverbal fluency task in comparison with low hostile men. It was also predicted that high-hostile males would display more perseverative errors than low- hostile males on the nonverbal fluency task as a function of regulatory interference. The results supported a capacity-limited prediction in high-hostile males. High-hostile males evidenced significantly heightened systolic blood pressure responses during the nonverbal fluency task in comparison with low hostile males. Further, high-hostile males displayed more perseverative errors in nonverbal fluency than did the low-hostile males. No differences were found in the overall fluency scores (verbal or nonverbal). These results partially support the expectation that differences exist between high and low hostile males for right frontal functioning. Moreover, these differences manifest in multiple domains of associated right frontal functioning. These findings extend the evidence for the proposed anterior-posterior inhibition model of hostility. / Master of Science

The relationship of current manual preference (phenotypic handedness) and family history of handedness (genotypic handedness) to memory for imageable stimuli was studied. The purpose of the study was to test the hypothesis that genotypic handedness was related to lessened cerebral lateralization of Paivio's (1969) dual memory systems. The structure of memory was not at issue, but the mediation of storage and retrieval in memory has been explained with reference to verbal or imaginal processes. Verbal mediation theories and supporting data were reviewed along with imaginal theories and supporting data for these latter theories. Paivio's (1969) dual coding and processing theory was considered a conceptual bridge between the competing positions.

Behavioral and physiological correlates of hostility, such as cardiovascular lability and increased risk of cardiovascular disease, are vital when considering the possible health risks associated with high levels of hostility (Henry & Meehan, 1981; Matthew & Haynes, 1986; Johnson, 1990; Heller, 1993; Heilman, Bowers, & Valenstein, 1993; Demaree & Harrison, 1997; Demaree Harrison, & Rhodes, 2000; and Shenal & Harrison, 2001). By examining this issue through a functional cerebral systems approach, one is better able to conceptualize changes that occur when men with extreme hostility levels (e.g. high and low) carry out emotional regulation tasks. High and low hostile groups have been shown to differ in their auditory, visual, somatosensory, and motor processes. Moreover, they differ in lateralized cerebral functions within these modalities where high hostiles have shown a right cerebral/ negative affective bias while low hostiles have shown a left cerebral/ positive affective bias in perception and in motor functions to stress. Right cerebral activation in high hostiles has occurred with heightened reactivity and persistence in sympathetic tone and with cardiovascular changes in heart rate, blood pressure, and Galvanic skin response. In the present experiment, this systematic line of research (Harrison & Gorelczenko, 1990; Herridge & Harrison. 1996; Demaree & Harrison, 1997; Herridge, Harrison, & Demaree, 1997; Demaree, Higgins, Williamson, and Harrison, 2002; Williamson & Harrison, in press) was extended to the investigation of the premotor frontal eye fields using rapid directional eye movements toward the contralateral hemisphere. It was predicted that high hostiles would evidence right frontal deficits in lateral eye movements (LEM) resulting in decreased LEM toward and within the left hemispace. Moreover, concurrent processing of lateralized eye movements and regulation over cardiovascular responding was predicted to yield sympathetic dysregulation on leftward LEM (lLEM) and potentially parasympathetic dysregulation on rightward LEM (rLEM). Leftward LEM appeared to result in more fatigue effects than rightward LEM. However, the primary behavioral hypothesis was not supported. Moreover, the directional relationship predicted between left side LEM and sympathetic tone was not found. Instead, LEM in either direction occurred with corresponding reduction in sympathetic blood pressure. Diametrically opposite results were found for the non- directional cold pressor stressor. High hostiles were found to be more reactive in their cardiovascular response to stress than the low hostiles. / Master of Science / [The Beck Depression Inventory, p. 62-66, was removed March 22, 2010 GMc]

No description available.

Cerebral lateralization was once thought to be unique to humans, but is now known to be widespread among the vertebrates. Lateralization appears to confer cognitive advantages upon those that possess it. Despite the taxonomic ubiquity and described advantages of lateralization, substantial individual variation exists in all species. Individual variation in cerebral lateralization may be tied to individual variation in behaviour and the selective forces that act to maintain variation in behaviour may also act to maintain variation in lateralization. Sex differences may also be an important source of variation in lateralization, as differences between males and females are often observed. Here, I present three papers that collectively deal with the interrelationships between sex, behaviour and cerebral lateralization in the convict cichlid. My results illustrate that lateralization is related to personality-like characteristics in the convict cichlid, and that there are important differences between the sexes in their pattern of lateralization.