Differences in visual attention processing: An event-related potential comparative analysis within psychotic disorders

>Magister Scientiae - MScINTRODUCTION: Sustained attention is known to be dysfunctional in psychotic disorders. Sustained attention is the ability to remain focused on a specific time-locked stimulus within a task. We aimed to determine whether there are specific group differences between CON and three psychotic disorders: SCZ, MPD and BPD, then to determine differences between these psychotic disorders. This included differences in behavioural performance and prominent electrophysiological event-related potential (ERP) wave components during cueing and target processing of a visual sustained attention task. Further we aimed to characterize ERP waveform component relationships across and within these groups for demographics, substance use, behavioural performance, and clinical variables, the last limited to the psychotic groups. Lastly, we investigated the effects of prescribed medications on ERP wave components within the psychotic groups. METHODOLOGY: 103 participants (29 schizophrenia (SCZ), 28 bipolar disorder with a history of psychosis (BPD), 21 methamphetamine-induced psychotic disorder (MPD), and 30 controls (CON)) underwent electroencephalography (EEG) record while completing a visual continuous performance task. Participants were presented with 60 trials with three consecutive S’s, the presentation of the third S required a behavioural response. Prominent ERP waveform components were extracted from cues and target stimulus. Group differences were determined by ANOVA with Bonferroni post-hoc correction or multivariate Kruskal-Wallis test dependent on data distribution. Relationships between ERP wave components were determined appropriate with Spearman’s Rank order correlation analyses. RESULTS: (1) MPD reported higher use of substances compared to CON, SCZ and BPD. SCZ behavioural performance was poorer compared to CON which was shown by their longer response times, reduced accuracy and increased errors of omission. Clinically, MPD was found to have a shorter duration of illness compared to SCZ. Then SCZ was found to have more positive symptoms compared to BPD whereas BPD had more negative symptoms compared to SCZ. For the first cue, wave component differences were found only over the left hemisphere, for P100 amplitude over the frontal cortex, P300 amplitude over the central cortex, and N170 amplitude over the parietal cortex. For the presentation of the second cue, differences noted for all groups were localised to the frontal and central brain regions, for P100 and N170 ERP waveforms. For the target stimulus wave component differences were found over the prefrontal, frontal and parietal brain regions, within CON, SCZ, BPD and MPD. (2) For the first cue, education positively correlated with the N170 left parietal amplitude in CON and P300 right parietal amplitude in MPD. During the second cue, the left parietal N170 latency in SCZ correlated positively with education and the left central P300 latency correlated negatively with education in MPD. The age on the day of testing correlated positively with the target left frontal P300 latency in MPD. For the first cue, substance use positively correlated with the left and right parietal P300 latency and negatively for the right parietal P100 amplitude in SCZ. In MPD, a negative correlation was noted across left and right prefrontal N170 and P300 amplitudes, and positive correlation for the left prefrontal P300 latency in MPD. For the target stimulus, correlations were evident for the left and right parietal N70, N170 amplitudes, P300 latency, the right parietal P100 amplitude and left central P300 latency in SCZ. For the first cue, in SCZ PANSS total score correlated positively with left and right central P300 amplitudes and the left parietal P300 amplitude. For the second cue; in MPD, the PANSS negative symptom score, positively correlated with the P100 and N170 left parietal amplitude, left and right parietal P150 amplitude, left central and right parietal P300 amplitude. For the target, the Hamilton depression rating scale correlated positively with the left and right frontal P300 amplitude in MPD and then negatively with the right parietal P300 amplitude in SCZ. Behavioural performance in CON, positively correlated with the left parietal N70, P100, P150 and N170 amplitude the number of correct responses, and left central N170 amplitude. While the number of impulsive responses correlated negatively with the left parietal N70, P100, P150 and N170 and the left central N170 amplitude of CON. For the second cue, behavioural performance was related to the fronto-parietal relationship across all groups. For the target stimulus, impulsive responses positively correlated with the left parietal N70 latency in SCZ. Overall response time negatively correlated with the right parietal P300 latency for SCZ. (3) Medication was found to affect ERP wave components during the sustained visual attention task. For the first cue FGA’s increased the left central P100 amplitude in both SCZ and BPD and decreased the left parietal P100 amplitude in SCZ only. The use of antipsychotics increased the right parietal N70 and left central P100 amplitudes in BPD, specifically the right prefrontal N170 amplitude was increased with the use of SGA’s. Then clozapine use increased the left frontal P100 amplitude in SCZ. For the second cue, SGA’s decreased the right parietal P150 amplitude in SCZ but in MPD the right parietal P150 amplitude was increased with haloperidol use, and FGA. SGA’s increased the left parietal P300 latency in BPD and sodium valproate decreased the left prefrontal P300 latency. For the target stimulus, SGA’s decreased the right parietal P100, P150 and left parietal P150 amplitudes and increased the left central P300 latency in BPD. CONCLUSION: (1) sustained attentional performance is poorer in SCZ. Our study adds to previous studies showing attention processing deficits in SCZ, are evident during cueing of a sustained attention tasks; (2) substance use was found to slow cognitive processing, education improved executive function and information processing, and symptom severity was associated with dysfunction of prefrontal and frontal cortices; (3) antipsychotic medication was related to improved processing of salient information. These data support the current literature and provide novel insights to the attentional processing deficits during cueing in the psychotic disorders

Differences in visual attention processing: An event-related potential comparative analysis within psychotic disorders

>Magister Scientiae - MScIntroduction: Sustained attention is known to be dysfunctional in psychotic disorders. Sustained attention is the ability to remain focused on a specific time-locked stimulus within a task. We aimed to determine whether there are specific group differences between CON and three psychotic disorders: SCZ, MPD and BPD, then to determine differences between these psychotic disorders. This included differences in behavioural performance and prominent electrophysiological event-related potential (ERP) wave components during cueing and target processing of a visual sustained attention task. Further we aimed to characterize ERP waveform component relationships across and within these groups for demographics, substance use, behavioural performance, and clinical variables, the last limited to the psychotic groups. Lastly, we investigated the effects of prescribed medications on ERP wave components within the psychotic groups. Methodology: 103 participants (29 schizophrenia (SCZ), 28 bipolar disorder with a history of psychosis (BPD), 21 methamphetamine-induced psychotic disorder (MPD), and 30 controls (CON)) underwent electroencephalography (EEG) record while completing a visual continuous performance task. Participants were presented with 60 trials with three consecutive S’s, the presentation of the third S required a behavioural response. Prominent ERP waveform components were extracted from cues and target stimulus. Group differences were determined by ANOVA with Bonferroni post-hoc correction or multivariate Kruskal-Wallis test dependent on data distribution. Relationships between ERP wave components were determined appropriate with Spearman’s Rank order correlation analyses

Investigating cortical arousal and cognition in schizophrenia and methamphetamine-induced psychotic disorder: an electroencephalography and cytokine study

Introduction: Schizophrenia (SCZ) and methamphetamine-induced psychotic disorder (MPD), are psychotic disorders characterized by positive symptoms (e.g., hallucinations and delusions), negative symptoms (e.g., social withdrawal, apathy), and impaired cognitive function. Despite the overlap in the clinical presentation of SCZ and MPD, no studies have compared electroencephalography (EEG) and inflammation across these two conditions. This study aimed to investigate key differences in brain electrical activity on EEG between SCZ and MPD by investigating; (1) relative frequency (alpha, theta, beta and delta) at rest; (2) cognitive performance and relative frequency activity during the continuous performance task (CPT) and cued target detection task (CTD); (3) differences in the P300 event-related potential waveform (ERP), a measure of attention, during the CPT and CTD; (4) cognitive performance and relative frequency and ERP (N170, P300) during the STROOP task, a measure of working memory and executive function; (5) the associations of (neuro) inflammatory markers with relative frequency and the P300 ERP waveform. Methods: 104 South African individuals, between the ages of 20 and 45 years, participated in this study: 69 outpatients (38 with SCZ (8 females/30 males), 31 with MPD (7 females/24 males)), and 35 healthy controls (CON: 15 females/20 males). All participants underwent a Structured Clinical Interview for Diagnostic Systematic Manual-IV (SCID-DSM-IV), with modifications to include changes made in DSM-5. EEG band frequency oscillations were recorded during baseline conditions: resting eyes open and resting eyes closed, and cognitive tasks (CPT, CTD and the Stroop task). Blood was drawn via venepuncture and serum was used for the analysis of cytokines (interleukin (IL) -1β IL-8, IL-10, IL-12p70, tumour necrosis factor-alpha and interferon-gamma (IFN-γ)) concentrations. Statistical analysis included assessment of normality using the Shapiro- Wilk test, with univariate one-way analysis of variance (ANOVA) of parametric data, and multiple independent Kruskal-Wallis ANOVA for non-parametric data (p

Unsettling Colonial Structures in Education through Community-Centered Praxis

In the context of settler colonialism in the US, mainstream education practices function as ongoing enactors of colonial processes. Decolonizing pedagogy seeks to challenge these dominant practices by centering place, Indigenous epistemologies, and rehumanizing values. In this paper, we discuss how faculty and students used community-based experiential learning projects (CBEL) to challenge these dominant and normative educational structures. By integrating an anti-racist and anti-colonial lens, CBEL projects themselves can work to dismantle power structures, build community, and promote experiential learning in a variety of educational spaces. The student projects presented here seek to unsettle colonial educational frameworks of white supremacy and white privilege by promoting counter-hegemonic critical thinking skills and incorporating culturally sustaining work with college faculty/students, outdoor educators, K-12 teacher preparation, and Indigenous communities

Unsettling Colonial Structures in Education through Community-Centered Praxis

In the context of settler colonialism in the US, mainstream education practices function as ongoing enactors of colonial processes. Decolonizing pedagogy seeks to challenge these dominant practices by centering place, Indigenous epistemologies, and rehumanizing values. In this paper, we discuss how faculty and students used community-based experiential learning projects (CBEL) to challenge these dominant and normative educational structures. By integrating an anti-racist and anti-colonial lens, CBEL projects themselves can work to dismantle power structures, build community, and promote experiential learning in a variety of educational spaces. The student projects presented here seek to unsettle colonial educational frameworks of white supremacy and white privilege by promoting counter-hegemonic critical thinking skills and incorporating culturally sustaining work with college faculty/students, outdoor educators, K-12 teacher preparation, and Indigenous communities

Generalizability of the guidance hypothesis to a brief acquisitions phase

Three experiments were conducted to Investigate the generality of the guidance hypothesis to a brief practice (acquisition) session. Three research paradigms were studied consistent with those outlined by Schmidt (in press). Schmidt has been vocal in advocating the notion that frequent knowledge of results (KR) degrades learning. In experiment 1 the relative frequency of KR was investigated by employing four frequency conditions with a 5-trial acquisition phase. Summary-KR was studied in Experiment 2, utilizing three different summary lengths with a 15-trial acquisition phase. Finally, the trials-delay procedure was considered in Experiment 3. There were four varieties of delay, each having a total of five KR statements. In all three experiments the task involved a limb movement from left key to right key, performed in a criterion time of 500 milliseconds. All three experiments employed an immediate retention test (10 minutes later) and a delayed retention test (2 days later) to determine if the experimental conditions affected learning

Characterising the fluctuation of microRNA expression throughout a full menstrual cycle

When processing a crime scene, obtaining a DNA profile that can identify an individual is extremely important. However, the identification of the body fluid that the sample was obtained from could provide key information of the events that occurred. microRNA (miRNA) expression analysis is a technique that has the potential to differentiate body fluids. The presence and expression of body fluid specific miRNA would provide a fast and effective tool for progressing crime scene investigation, especially alleged sexual assault cases. Forensic case work lacks methods for identifying vaginal material, venous blood, menstrual blood and aspermatozoic seminal fluid within samples. A large screening study followed by a 31 day study on five female volunteers was performed utilising RT-qPCR on a large panel of body fluid markers. Screening showed a selection of markers were suitable to differentiate each body fluid, in some cases however, expression fluctuated when analysed over a 31 day period. The data shows that hsa-miR-412 may be suitable for identifying menstrual blood, expression from markers hsa-miR-124 and hsa-miR-205 varied significantly over the 31 day period and between individuals and therefore were less suitable for body fluid identification. The data supports the use of miRNA markers for the identification of certain body fluids such as menstrual and venous blood; however markers for the identification of body fluids such as vaginal material and saliva require further investigation

The Library Derived 4554W Peptide Inhibits Primary Nucleation of α-Synuclein

Aggregation of alpha-Synuclein (aS) is widely regarded as a key factor in neuronal cell death, leading to a wide range of synucleinopathies that includes Parkinson’s Disease. Development of therapeutics has therefore focused on inhibiting aggregation of aS into toxic forms. One such inhibitor, based on the preNAC region aS45-54 (4554W), was identified using an intracellular peptide library screen, and subsequently shown to both inhibit formation of aS aggregates while simultaneously lowering toxicity. Subsequent efforts have sought to determine the mode of 4554W action. In particular, and consistent with the fact that both target and peptide are co-produced during library screening, we find that the peptide inhibits primary nucleation of aS, but does not modulate downstream secondary nucleation or elongation events. These findings hold significant promise towards mechanistic understanding and development of molecules that can module the first steps in aS aggregation towards novel treatments for Parkinson’s disease and related synucleinopathies

A Preliminary Examination of Power Relationships’ Influence on Reducing the Digitally Marginalized Student Population in Jamaica.

The Digital Divide has historically been viewed as the separation of people from technology based primarily on socio-economic issues and other demographic vulnerabilities. More recent studies have expanded research into investigating the impact of other societal structures such as the power of the government on equitable distribution of Information & Communication Technologies (ICTs) and other resources to the digitally marginalized population. While many strides have been made, educating children in the post-Covid era has made resolving the Divide a more pressing issue for students living in developing countries like Jamaica, where pre-pandemic, technology in education was still in its infancy. Using the Grounded Theory methodology, this research introduces preliminary findings demonstrating four power-relationships that have the power to and the power over effectively bridging the Divide and amongst the youngest of the digitally marginalized population and its effect on state-sponsored initiatives such as the OYOD