<p>The development of alcohol use disorder (AUD) is believed to involve functional adaptations in corticostriatal projections which regulate the reinforcing properties of ethanol (EtOH). To further our understanding of how repeated EtOH consumption impacts the corticostriatal circuit, extracellular electrophysiological recordings (local field potentials; LFPs) were gathered from the nucleus accumbens and prefrontal cortex of female and male C57BL/6J mice voluntarily consuming EtOH or water using ‘drinking-in-the-dark’ (DID) procedures. Mice were given 15 consecutive days of two-hours of access to EtOH (20% v/v), three hours into the dark cycle while LFPs were recorded. To determine the impact of repeated EtOH consumption on neural activity between these brain regions, theta phase-locking value (PLV, a measure of synchrony) was calculated. Specifically, theta PLV was calculated during active drinking periods (bouts) and average PLV during the first bout was compared to the last bout to determine within session changes in synchrony. Results indicated significantly lower PLV during the last bout than the first bout. Additionally, longer bouts predicted lower PLV during the last bout, but not the first bout when mice were consuming EtOH. These results may suggest that alcohol intoxication decreases corticostriatal synchrony over a drinking period. Results considering changes in theta power spectral density (PSD) indicated an increase in PSD when mice were given access to water during the typical EtOH access time following the 15-day EtOH drinking history. This effect was not seen when mice were drinking water prior to EtOH access and may be indicative of a successive negative contrast effect. This work identifies unique functional characteristics of corticostriatal communication associated with binge-like EtOH intake and sets the stage for identifying the biological mechanisms subserving them.</p>

To investigate the possibility that chronic diabetes mellitus was related to specific neuropsychological deficits, cognitive functioning was measured in subjects with diabetic retinopathy (without secondary disabilities), and in subjects classified as normal blind adults (also without secondary disabilities). The scores for the two groups were then compared.

The blind have generally been considered to be a homogeneous population whose deficits arise from an interaction of loss of vision, age of onset and socialization. Sequelae are posited to exist merely due to the limiting effects of blindness on experience. This is believed to affect all blind persons equally regardless of cause of blindness provided that independent secondary disabilities do not exist. This study investigated the possibility that different causes of blindness are related to specific neuropsychological deficits which cannot be explained by the mere presence of blindness. It was found that neuropsychological differences existed among specific sub-populations of blind persons. These results suggested that the cause of blindness may be a marker for specific Central Nervous System involvement.

It has been hypothesized that a disproportionate percentage of the blind population are learning disabled. In the past, norms and technology were not available to assess in a cost effective manner the blind client's neuropsychological functioning. Norms for the Wide Range Achievement Test - Revised (WRAT-R2) are now available for a blind population without any neuropsychological dysfunctioning. This study utilized the adapted WRAT-R2 and the Comprehensive Vocational Evaluation System (CVES), a neuropsychological test battery adapted for the blind, to investigate the possibility that learning disabilities are present in the adult blind population. Suspected learning disabled, blind subjects were compared with normal blind subjects. There were significant neuropsychological differences between the two groups.

Given that neurocognitive impairment is a frequent complication of HIV-1 infection in Spanish-speaking adults, the limited number of studies assessing HIV-associated neurocognitive disorders (HAND) in this population raises serious clinical concern. In addition to being appropriately translated, instruments need to be modified, normed, and validated accordingly. The purpose of the current study was to examine the diagnostic utility of the HIV Dementia Scale (HDS) and International HIV Dementia Scale (IHDS) to screen for HAND in Spanish-speaking adults living with HIV infection. Participants were classified as either HAND (N = 47) or No-HAND (N = 53) after completing a comprehensive neuropsychological evaluation. Receiver operating characteristic analyses found the HDS (AUC =.706) was more sensitive to detecting HAND than the IHDS (AUC =.600). Optimal cutoff scores were 9.5 for the HDS (PPV = 65.2%, NPV = 71.4%) and 9.0 for the IHDS (PPV = 59.4%, NPV = 59.1%). Canonical Correlation Analysis found the HDS converged with attention and executive functioning. Findings suggest that while the IHDS may not be an appropriate screening instrument with this population, the HDS retains sufficient statistical validity and clinical utility to screen for HAND in Spanish-speaking adults as a time-efficient and cost-effective measure in clinical settings with limited resources.

Neuropsychological assessment in linguistically heterogeneous populations is fraught with numerous challenges, such as lacking or inappropriate normative data or the unavailability of appropriate tests. Accommodating multilingual individuals exacerbates the issue by adding the question of which language(s) to use when assessing multilingual individuals. Different testrelated concepts may be accessible to them via different languages, as their lexicon is spread out over two or more languages. Hence, any monolingual instrument is likely to disadvantage them. The present set of three studies circumvents this question and presents evidence for an inherently multilingual English/Afrikaans/isiXhosa screening tool for intelligence, the Multilingual Vocabulary Test (MVT). I describe the instrument’s development from the pilot study to a psychometric analysis of the final, digitally administered version. For an abbreviated 13-item version, Study 3 (N = 494) shows an internal consistency of  = .59 and Study 2 (N = 101) produced significant criterion-related validity values of r = .46 and r = .52 with the KBIT-2 and Shipley-2 VIQ scores respectively. Linear regression analyses show that, while all criterion measures are biased toward E1-speakers, the MVT is largely immune to test-takers’ linguistic background. Thus, the MVT paves the way toward more fairness in cognitive assessments, in general, and provides a promising first step toward addressing one of South African neuropsychologists’ greatest needs—that of a quick and easy-to-administer, yet linguistically fair screening tool for cognitive impairment.

Researchers have found executive functioning (EF) to be important for reading and math performance but have paid less attention to their role in writing. Van Dijk and Kintsch (1983) identified three levels of writing: microstructure, macrostructure, and superstructure. The existing work on EF and writing has several limitations: researchers have primarily focused on microstructural writing in children, studied a limited range of EF, not included measures of self-reported EF to compare to laboratory-/lab-based-based measures of EF and not examined the differential contributions of multiple EF to the different levels of writing. Hence, the purpose of this study was to better understand the differential involvement of various laboratory and self-reported EF across various levels of micro- and macrostructural writing measures in emerging adult writing. Results indicated that inhibition was a significant predictor of microstructural writing, such that working carefully increases the accuracy of spelling and mechanics skills. Working memory was related to microstructural grammar and mechanics sentence formulation, potentially through processing the sentences, mentally manipulating the sentence structure, and recording the response while maintaining the sentence information in mind. Verbal fluency was related to microstructural spelling and grammar and mechanics accuracy, as well as macrostructural essay organization, possibly through the ability to efficiently retrieve knowledge critical to perform these tasks. The main analyses did not yield significant results for macrostructural theme development, likely due to methodological issues, but an exploratory analysis demonstrated that organization and problem solving skills predicted theme development, potentially through the ability to think critically about, and organize, the arguments made. Finally, lab-based EF measures were better predictors of the writing measures than the self-reported EF measure, suggesting that these two methods captured different aspects of EF, and that the lab-based predictors were more appropriate to use with lab-based outcome variables, likely due to their narrower and less environmentally-influenced constructs. The results of this study help inform the factors that contribute to writing skills, and this knowledge can be used to improve the detection of writing difficulties and to target writing interventions.

This thesis presents research aimed at elucidating neurophysiological and neuropsychological correlates of two psychiatric disorders, schizophrenia and PTSD. Although psychiatric disorders are not traditionally known for featuring cognitive deficits, research over the past three decades has revealed that deficits in many aspects of cognitive functioning are present across a wide range of disorders. Here, we aim to further our understanding of these deficits and provide evidence of the clinical utility of neurophysiological correlates of cognitive dysfunction. The cause and course of cognitive deficits in PTSD is poorly understood, and an investigation of one potential explanatory mechanism, dissociative symptomatology, is presented in the first part of this thesis. Our results suggest that dissociative symptomatology plays a role in cognitive dysfunction in PTSD, as among the clinical variables tested (including PTSD symptomatology, dissociative symptoms, depressive symptoms, and anxiety symptoms) dissociative symptoms were the only significantly correlated variables to cognitive dysfunction in a sample of combat-trauma exposed veterans with and without PTSD. In the second part of this thesis, we investigate the potential clinical utility of a neurophysiological biomarker for semantic processing deficits, the N400, in schizophrenia. Our results indicate that N400 measures are stable over a one week period and therefore may be clinically useful as a neurophysiological biomarker for semantic processing abnormalities in schizophrenia. Overall, these two studies contribute to our knowledge of cognitive deficits in psychiatric disorders and demonstrate their complexity as well as their potential to provide clinically useful tools to aid in the identification of novel treatments targeted at ameliorating cognitive deficits in schizophrenia and PTSD. / Thesis / Master of Science (MSc)

An evaluation of executive functioning is a critical component of a comprehensive assessment of higher cerebral functioning. The Tinker Toy Test (TTT) was introduced in 1982. This test allows an individual to demonstrate the extent of their executive capacities by permitting them to initiate, plan, and structure a potentially complex activity and carry it out independently in an unstructured fashion and administration is simple. This is a departure from more complex and structured tests of executive function. There is a dearth of research on the TTT and this study seeks to examine some of the psychometric properties of this instrument; i.e., working time minimum, gender effects, convergent and divergent validity, and potential intellectual correlates. Participants included 10 male and 30 female student volunteers from a large university in Central Florida. Participants had no history of neurologic disease/trauma or conditions that would affect motor functioning of the upper extremities. Participants completed a demographic questionnaire, the WASI-II, and the TTT. A two-way mixed-design ANOVA examining TTT scores as a function of work time and gender revealed a non-significant gender main effect, F(1, 21) = .09, p = .767. The work time main effect was not significant, , F(1, 21) = .324, p = .575. A significant work time x gender interaction was observed, F(1, 21) = 4.983, p = .037. Convergent validity was assessed by comparing the TTT scores with the Matrix Reasoning subtest, r(38) = .32, p = .044, and the Similarities, r(38) = .34, p = .03, subtest on the WASI-II. Divergent validity was assessed by comparing TTT scores to the Block Design subtest of the WASI-II, r(38) = .245, p = .127. No significant correlation was found between intelligence and TTT (VCI, r(38) = -.16, p = .335; PRI, r(38) = .15, p = .344; and FSIQ, r(38) = -.02, p = .928). The data supports the continued use of the 5-minute working time minimum presented by Lezak, as this temporal index was a more accurate representation of executive functioning. This study demonstrated no association between TTT scores and intellectual functioning. The findings of this study support the validity of this underutilized test of executive functioning and its inclusion in neuropsychological test batteries.

Regardless of the reason, many patients/clients do not have access to face-to-face medical, neuropsychological, or mental health consultation, assessment, or treatment (Cowain, 2001). The term Remote Neuropsychological Assessment (RNA) has been proposed by Browndyke to denote the general use of telecommunication and Internet-based technologies in neuropsychological assessment and practice (as cited in Schatz & Browndyke, 2002). RNA (Telemedicine) offers a plausible, potentially cost-effective solution to individuals in need of medical, neuropsychological, or mental health consultation, assessment, or treatment that are located in geographical areas away from the specialist (Armstrong, 2006; Berman, 2005; Cowain, 2001; Jacobsen, Sprenger, Andersson, & Krogstad, 2003). The purpose of this study was to examine if test performance for RNA administration of the Cognistat is comparable to test performance for the pencil-paper administration. A one-way repeated measures multivariate analysis of variance (MANOVA) was used to analyze the data. The main effect for administration modality was not significant, F(9, 126) = .375, p = .945. The present study demonstrated the utility of a widely used neurobehavioral screening test that provides a differentiated profile of cognitive status can now reliably be used through a video-conferencing administration. The importance of this finding is that a more comprehensive detection of deficits in multiple domains of cognitive functioning for screening purposes is now possible remotely.