Is the term ‘hallucination’ as it is used within the context of generative AI merely a metaphor? An investigation how hallucinations arise in the human perceptual system and in modern generative AI
Research master thesis | Psychology (research) (MSc)
open access
2024-08-31T00:00:00Z
Prior studies have shown ambiguous results concerning the question if and how cognitive performance and neurophysiological markers change under the influence of weightlessness. Additional research...Show morePrior studies have shown ambiguous results concerning the question if and how cognitive performance and neurophysiological markers change under the influence of weightlessness. Additional research is necessary to confirm effects and shed light on experimental and interindividual differences and those related to various mechanisms underlying cognitive processes. This study aimed to assess the influence of microgravity on the neurocognitive marker P3 during parabolic flight. METHODS: Participants were trained to perform a brain-computer interface (BCI) task, which included a visual oddball paradigm task. Nine participants performed this task during parabolic flight. Statistic analyses assessed the amplitude and latency of the P3 event-related potential (ERP). RESULTS: Results revealed no significant differences for P3 Amplitude nor Latency in the 0G condition versus the 1G condition. The amplitude for oddball stimuli was significantly higher than the amplitude for standard stimuli in both 1G and 0G. CONCLUSION: There needs to be greater consensus and understanding concerning the effects of microgravity on cognitive performance and ERPs. The data presented here does not verify that short bouts of microgravity could enhance nor diminish neuro-behavioral performance. It does confirm that the visual-based oddball paradigm is feasible in microgravity conditions.Show less
Multiple Sclerosis (MS) is a chronic disease of the central nervous system that affects an estimate of 2.8 million people worldwide. Fatigue, impairments in processing speed, and depression are...Show moreMultiple Sclerosis (MS) is a chronic disease of the central nervous system that affects an estimate of 2.8 million people worldwide. Fatigue, impairments in processing speed, and depression are common symptoms reported by People with MS (PwMS). However, the relationship between these symptoms is not well understood. This study aimed to investigate this relationship and examine the (in)stability of fatigue levels over time in PwMS. The study utilized a longitudinal, retrospective cohort design and included participants diagnosed with MS (n= 141) who attended a specialized clinic in Overpelt, Belgium. Seventy-three percent of the sample was female, with a mean age of 51.88 (SD ±13.46). The average disease duration was of 16.94 years (SD ± 8.86), and a majority of the sample had the relapsing-remitting type of MS (RRMS) (n= 43). The median of disease severity, as measured by the EDSS, was of 3.50 (IQR – 3.5). The study hypothesized that fatigue levels would increase over time and that depression would moderate the relationship between fatigue and processing speed. Fatigue levels did not significantly change over time (p = 0.055). A significant relationship was found between fatigue and processing speed impairment (p < 0.05). However, depression did not significantly moderate this relationship (p = 0.215). These findings show that cognitive symptoms may influence each other in MS. Future research should look into the relationship of mood disorders, such as anxiety and depression, and cognitive impairment in PwMS.Show less
Background. Pediatric brain tumor patients are known to experience cognitive problems. It is important to recognize that pediatric cancer patients and their families face significant distress from...Show moreBackground. Pediatric brain tumor patients are known to experience cognitive problems. It is important to recognize that pediatric cancer patients and their families face significant distress from the moment of diagnosis. The early screening and treatment of stress symptoms may help to reduce cognitive problems and improve the quality of life for pediatric brain tumor survivors. The main aim for this thesis was to evaluate whether there is an association between medical (traumatic) stress and cognition, within the first year of diagnosis in pediatric brain tumor patients. It was hypothesized that on average, cognitive performance and stress would improve and that patients with persistent stress or increased medical (traumatic) stress would experience more cognitive difficulties. Method. The longitudinal study included 74 pediatric brain tumor patients. Stress was measured with a questionnaire and cognition was measured with neuropsychological assessments on the cognitive domains of attention, executive functioning, processing speed, and memory. Patients participated at two time points, shortly after diagnosis and one year after diagnosis. One-sample t-tests were used to compare the z-scores of the cognitive domains at both time points. Paired t-tests were used to examine stress and cognition over one year. To examine an association a linear mixed model was performed, predictors included stress and time since diagnosis. Results. On average, medical (traumatic) stress improved over one year, with a subgroup of patients experiencing increased and/or persistent stress throughout the year. The cognitive domain of attention was mostly impaired with no improvement over one year. Executive functioning and processing were mostly impaired at the beginning of diagnosis, with improvements over one year. Memory was not impaired. Moreover, there was no association found between medical (traumatic) stress and cognition. Conclusion. This study showed that it is important to test for cognitive performance and medical (traumatic) stress shortly after diagnosis and over the course of one year. New insights from early testing could benefit clinical implications and interventions to improve the quality of life. For future research, objective measures of medical (traumatic) stress and a healthy matched control group should be added.Show less
Vascular reactivity is defined as the ability of arteries to dilate or constrict as a reaction to changes in metabolite concentrations and is nowadays measured by the BOLD-response rather than with...Show moreVascular reactivity is defined as the ability of arteries to dilate or constrict as a reaction to changes in metabolite concentrations and is nowadays measured by the BOLD-response rather than with transcranial doppler ultrasound. Previous studies have shown that vascular reactivity is related to small vessel disease and cognition. However, it is unclear whether cognition remains associated with vascular reactivity when measured by the BOLD-response and whether these associations are (in)dependent of classic small vessel disease markers. Therefore, in this cross-sectional observational study we examined the associations between the BOLD-response and cognition and the (in)dependence of the significant associations from five classic small vessel disease markers. Our first hypothesis was that vascular reactivity is also associated with cognition when measured by the BOLD-response. Secondly, we hypothesized that the significant associations between vascular reactivity and cognition were dependent on microbleeds and perivascular spaces in the centrum semiovale. The latter hypothesis was based on studies into cerebral amyloid angiopathy, a specific small vessel disease, that is associated with lower vascular reactivity, cognitive deterioration, and the presence of microbleeds and perivascular spaces in the centrum semiovale. We determined vascular reactivity by measuring the peak time, baseline time, and amplitude of the BOLD-response in the occipital cortex after a visual stimulus. Composite z-scores for global cognitive functioning, memory, executive functioning, psychomotor speed, and language were calculated from cognitive tests obtained during a neuropsychological assessment. The five small vessel disease markers were assessed via MRI-scans. Results of bootstrapping analyses showed that only the BOLD-amplitude was associated with global cognitive functioning, memory, executive functioning, and language. These associations were mostly independent of small vessel diseases markers. Based on these findings, we suggest that vascular reactivity measured by the BOLD-amplitude might be an early relatively independent predictor of cognition decline, what might enable early detection and as a consequence early intervention. All in all, our findings underline the role of vascular aspects in cognition, although the causality of the associations is yet unclear and future research into the underlying processes of vascular reactivity and the BOLD-response is of great importance to further clarify our findings.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Patients with Duchenne muscular dystrophy (DMD) lack the full-length dystrophin protein. In muscle this protein contributes to membrane integrity. It is also found in the brain, but its function...Show morePatients with Duchenne muscular dystrophy (DMD) lack the full-length dystrophin protein. In muscle this protein contributes to membrane integrity. It is also found in the brain, but its function there is unclear. Patients with DMD experience a number of cognitive and behavioral problems, and MRI studies have shown reduced gray matter and total brain volume. The current study aimed to assess whether these MRI findings are progressive and whether neural correlates of psychological problems in DMD are similar to those in healthy controls. Previously-acquired pediatric data was combined with newly-acquired data from adult DMD patients and age- and sex-matched healthy controls. Subjects underwent a magnetic resonance imaging scan and a neuropsychological evaluation. Linear mixed models were used to assess the effect of age and DMD on the ratio of gray matter to cerebrospinal fluid volume (GMV:CSFV) and total brain volume corrected for intracranial volume (TBV:ICV). An independent-samples t-test and a voxel-based morphometry analysis were used to compare gray matter volume in patients with psychological problems to patients without such problems, to identify global or local gray matter reductions in patients with psychological problems. Patients with DMD had reduced GMV:CSFV and TBV:ICV compared to healthy controls (b=-0.43, p<0.001; b=-0.02, p<0.001 respectively). Both GMV:CSFV and TBV:ICV linearly decreased in both groups (b=-0.09, p<0.001; b=-0.003, p<0.001 respectively), but this was not different between-groups (p>0.05). No global (p>0.05) or localized gray matter volume reductions were found in patients with DMD with psychological problems compared to patients without such problems. In both patients and healthy controls gray matter was displaced by cerebrospinal fluid over time, suggesting this process is not a pathological mechanism in DMD. Patients with DMD did have a lower GMV:CSFV and TBV:ICV ratio, suggesting this is a diseased mechanism. No global or local GM reductions were found in patients with DMD with psychological problems compared to patients without such problems.Show less
Brain metastases are the spread of primary cancer elsewhere in the body to the brain, that are typically treated with a technique called stereotactic radiotherapy. Whereas the short-term changes...Show moreBrain metastases are the spread of primary cancer elsewhere in the body to the brain, that are typically treated with a technique called stereotactic radiotherapy. Whereas the short-term changes within cognition after stereotactic radiotherapy are widely studied, the long-term effects are still relatively unknown. This longitudinalstudy aimed to assess the late effects of stereotactic radiotherapy on cognitive functioning in patients with brain metastases, emphasizing cognitive decline. In addition, this study compared different methodological approaches to measure cognitive changes and examined possible risk factors of cognitive decline. Forty-two brain metastasis patients completed a validated neuropsychological test battery assessing their cognitive functioning at baseline and nine-months follow-up. The battery yielded ten cognitive outcomes, and we defined cognitive decline as impairment on ≥2 outcomes. We used three approaches to calculate the cognitive decline, namely a Reliable Change Index not correcting for practice effects (RCI), a RCI correcting for practice effects (RCI+PE), change and Z-scores. We tested the three measures of cognitive decline for significant differences, providing insight into the sensitivity of the approaches to measure cognition over time. Lastly, we did determine whether age, the baseline level of cognitive functioning, volume and number of brain metastases were predictive of cognitive decline using a binary logistic regression. Our results revealed a cognitive decline in 31% of brain metastasis patients (p < .001). Most decline was found in verbal memory. In addition, the percentage of patients who showed cognitive decline as measured with the RCI+PE was significantly higher than found with a change in Z-scores (p = .014). No significant predictors of cognitive decline were found (p = .213). In addition to the known immediate cognitive effects (< 6 months after treatment), we demonstrated that a significant proportion of patients with brain metastases still shows cognitive decline nine months after stereotactic radiotherapy. Consequently, clinical decision-making about treatment options and psycho-education should include those late effects. Furthermore, we found that the RCI+PE can significantly detect more cognitive decline than the difference in Z-scores, providing a recommendation for future research to use an RCI+PE as a measure of change in cognition over time.Show less
Considering the many children around the world that live in financially scarce conditions, it is of importance to know the consequences with regard to cognition. Life history theory suggests people...Show moreConsidering the many children around the world that live in financially scarce conditions, it is of importance to know the consequences with regard to cognition. Life history theory suggests people growing up in these scarce circumstances might develop different ways of adapting to this environment. This study looks at the influence of childhood financial scarcity on cognitive performance, when a current mindset of financial scarcity is activated. Specifically, this research is focused on determining performance on inhibition and cognitive switching tasks for people with different scarcity backgrounds and mindsets. In order to test this, people were questioned about their childhood. Then, half of the participants was instructed to recall a scarcity-related memory, while others recalled a neutral memory. Finally participants were presented with a cognitive task, which measured either inhibition or cognitive switching. It was expected that in a current scarcity mindset, people that had a scarcity background would perform lower on inhibition, but higher on switching. According to the results, neither childhood scarcity, current scarcity mindset, nor the combination of the two, were significant predictors of performance on the cognitive tasks. On these grounds, further research is needed to determine the relation between scarcity and cognition.Show less
Children who are born with perinatal asphyxia (PA) in the Netherlands, have been treated with therapeutic hypothermia (TH) since 2018. So far, little is known about the cognitive outcome of these...Show moreChildren who are born with perinatal asphyxia (PA) in the Netherlands, have been treated with therapeutic hypothermia (TH) since 2018. So far, little is known about the cognitive outcome of these children. This study explores a possible interaction effect between birthweight and TH on Total IQ and Processing Speed in children 10 years of age known with PA. Some of the children treated with TH were also cognitive assessed at the age of 5 year. For these children, we looked at the course of cognitive development between 5 and 10 years of age. Fifty children were assessed at the age of 10 years with the Wechsler intelligence scale (WISC-III-NL). Fifteen of these children were also assessed at the age of 5 years with the Wechsler Preschool and Primary Scale of intelligence (WPPSI-III-NL). There was no interaction effect found between TH and birthweight on Total IQ and processing speed scores assessed at the age of 10 years. Furthermore, there were no significant differences found between Total IQ and processing speed scores assessed at 5 and 10 years of age. Since this was only exploratory research more research is needed to draw more reliable conclusions.Show less
The menstrual cycle has been demonstrated to have wide-ranging effects on cognition and emotions. Specific mood syndromes are associated with particular phases of the menstrual cycle, and the...Show moreThe menstrual cycle has been demonstrated to have wide-ranging effects on cognition and emotions. Specific mood syndromes are associated with particular phases of the menstrual cycle, and the prevalence of mood disorders is higher in women. We aimed to investigate, whether the luteal phase of the menstrual cycle has a negative effect on anxiety levels, through temporarily increased attention to negative emotional stimuli, referred to as attentional bias (AB). We collected data on 194 healthy participants using online surveys and an emotional dot-probe task (eDPT), with pictorial stimuli of emotional facial expressions (angry, fearful, happy, and neutral). We aimed to investigate whether different groups of participants (follicular phase women (N = 30), luteal phase women (N = 24), oral contraceptive using women (N = 75), and men (N = 65)) would exhibit ABs in the eDPT. We hypothesized that luteal phase women would show larger AB for emotional stimuli, and, specifically, angry and fearful stimuli. Further, we expected that differences in state anxiety levels between the groups would account for differences in AB. Our results did not support our hypotheses. We found a significant AB for emotional faces over neutral faces, and different average response times depending on the specific emotion in a given trial. However, the magnitude of these effects was the same for follicular phase women, luteal phase women, OC users, and men. Further, these results were unaffected by state anxiety levels of the participants. From these results, we could conclude that there simply is no difference in AB for emotional stimuli between the chosen groups of participants, using the eDPT. Alternatively, methodological constraints might have contributed to these null findings.Show less
In this study the effects of using blue-light filter glasses on sleep quality and vigilance is investigated in 60 young adults, in order to gain more insight in blue-light filter glasses as an...Show moreIn this study the effects of using blue-light filter glasses on sleep quality and vigilance is investigated in 60 young adults, in order to gain more insight in blue-light filter glasses as an effective aid for poor sleep quality. Blue-light filter glasses were expected to have a positive effect on sleep quality and vigilance performance. This was a single-blind controlled study in which the participants reported their sleep quality on the PSQI and KSS and their vigilance performance was measured with the Psychomotor Vigilance Task. After two weeks of intervention, wearing blue-light filter glasses in the experimental condition and listening to music in the control condition, follow-up measures were registered. Measures of total sleep quality and sleep latency increased and vigilance reaction times decreased over time in the analysis of variances with repeated measures. These changes could not be explained by the use of blue-light filter glasses or the relation between vigilance and sleep quality. The expected positive relation between sleep quality and cognitive performance was not supported by these findings. In conclusion, this study does not provide convincing support for blue-light filter glasses as an effective aid for poor sleep quality. Among others, including objective measures and treatments with longer periods of time are recommended for future research.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Introduction Frontotemporal dementia (FTD) is a young-onset neurodegenerative disorder with treatments still being in development. For trials testing such treatments, sensitive instruments to...Show moreIntroduction Frontotemporal dementia (FTD) is a young-onset neurodegenerative disorder with treatments still being in development. For trials testing such treatments, sensitive instruments to assess treatment effects are essential. This exploratory study aimed to identify such instruments by investigating gene-specific, presymptomatic cognitive decline and the underlying neural mechanisms of this decline. Methods We examined longitudinal cognitive decline using mixed effects models with natural cubic splines in six different domains for carriers of genetic mutations in GRN (n=46), MAPT (n=22), C9orf72 (n=29), and healthy controls (n=84). A voxel-based morphometry analysis was used to correlate cognitive decline to grey matter volume decline for the three mutation carrier groups. Results MAPT and C9orf72 mutation carriers showed a steeper decline on language (χ2(6) = 21.78, p = .001) and memory (χ2(6) = 18.42, p = .005) compared to GRN mutation carriers and controls. Decline in executive functions was associated with larger grey matter volume decline in the left superior and right middle frontal gyrus for C9orf72 mutation carriers and decline in language was associated with larger grey matter volume decline in the right anterior insula for MAPT mutation carriers. Discussion This study provides evidence of gene-specific cognitive decline in presymptomatic genetic mutation carriers of FTD. The findings highlight the importance of both neuropsychological and neuroimaging assessment which can be used as sensitive diagnostic biomarkers to identify and track disease progression in genetic FTD.Show less
Background: Schizophrenia (SZ) and Bipolar disorder (BD) are severe mental disorders with a substantial genetic component. Cognitive dysfunction is a core feature of SZ and BD, and cognitive...Show moreBackground: Schizophrenia (SZ) and Bipolar disorder (BD) are severe mental disorders with a substantial genetic component. Cognitive dysfunction is a core feature of SZ and BD, and cognitive problems also occur in the offspring of SZ and BD patients. It is unclear how mood symptoms relate to cognition in this offspring group. This study examined the influence of the degree of mood symptoms, and therefore a more negative mood, on cognition in this high-risk offspring group by looking at mood symptoms as a continuous measure. As a follow-up, the effect of mood symptoms on cognition was examined again after four years. Methods: 134 SZ and BD offspring, and 49 controls performed the KSADS- PL (The Schedule for Affective Disorders and Schizophrenia for School-Age Children Present and Lifetime Version) and the ANT (Amsterdam Neuropsychological Tasks) at baseline (T1) and after approximately four years (T2). To examine if mood symptoms, age, sex, group (offspring or control), and the number of errors could predict cognitive scores on sustained attention, inhibition, and attentional flexibility, multiple linear regressions were performed. Results: At T1, sustained attention was the only cognitive domain that was associated with mood symptoms (B= .05, p= .001), indicating that more mood symptoms were related to worse sustained attention. Lower inhibition and attentional flexibility scores were predicted by age. At T2, sustained attention was significantly predicted by mood symptoms at T1 (B= .05, p= .001), indicating that more mood symptoms at T1 were associated with worse sustained attention after four years. Inhibition scores at T2 were not predicted by mood at T1, sex or age. At T2, attentional flexibility was predicted by age and sex. Group status (offspring or control) did not predict cognition. Conclusions: More mood symptoms are related to worse sustained attention in offspring and controls at baseline and after 4 years. Indicating that more mood symptoms in both the offspring and the control group caused lower sustained attention, rather than a genetic predisposition. Attentional flexibility and inhibition scores were not affected by mood symptoms at T1 and T2, but by age. Focusing on mood symptoms and their influence on cognition in high-risk offspring could help to refine and create screening and preventive methods and treatments.Show less
Objective: Multiple sclerosis (MS) is the most common neurodegenerative disease among young adults, of which 40-70% of the patients suffer from cognitive impairment. Currently, there is no...Show moreObjective: Multiple sclerosis (MS) is the most common neurodegenerative disease among young adults, of which 40-70% of the patients suffer from cognitive impairment. Currently, there is no biomarker predicting the cognitive status of MS patients. This study performed a principal component analysis in order to find a disease pattern that can aid in the differentiation of cognitive impairment in MS. Methods: A principal component analysis (PCA) was performed to create a disease pattern based on differences in whole-brain voxel intensities of conventional MRI sequences (T1, T2, and T2- FLAIR) and magnetization transfer (MT)-based MRI of 15 cognitively preserved MS patients (MSCP), 15 impaired patients (MS-CI) and 15 controls. A leave-one-out approach was used to validate the disease patterns between different cognitive performance statuses. Results: None of the conventional MRI sequences nor MT-based MRI were able to find a significant disease pattern for separating MS patients on cognitive status. The frontal cortex, periventricular zone, longitudinal fasciculus, thalamus and brainstem were more severely affected in cognitive impaired MS patients, although significance was not reached. Conclusion: Although the brain patterns created with both conventional MRI sequences and MTbased MRI sequences for evaluating cognitive performance in MS were not significant, the PCA is still a promising technique, when a larger sample size can be included.Show less
