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Open Access Publications from the University of California
Cover page of Invariant Representations of Mass in the Human Brain and Its Effects on Inferences on Physical Collisions

Invariant Representations of Mass in the Human Brain and Its Effects on Inferences on Physical Collisions

(2021)

From the moment they are born, infants begin to build an internal model of their physical world. This understanding of physical laws, commonly referred to as intuitive physics, develops over time, enabling individuals to successfully explore and interact with their surroundings. However, the cognitive mechanisms through which humans acquire this understanding of physical quantities, such as mass, are unknown. This paper discusses current understanding of a distinct but foundational part of the intuitive physics engine, mass representation. Current research has localized mass representation to dorsal frontoparietal, ventral-temporal, and dorsal premotor areas of the cortex. However, upon thorough literary analysis, the regions primarily responsible in this process have been narrowed down to the frontal and parietal regions. The extent to which these brain regions are responsible seems to be task dependent, opening avenues for further research to investigate the regions activated during other tasks involving different physical characteristics.

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Cover page of Significant Group-Level Brain Activity during Trail-Making Test Performance

Significant Group-Level Brain Activity during Trail-Making Test Performance

(2021)

The trail-making test (TMT) is a neuropsychological test that is often used to identify cognitive impairment and dementia. This paper replicates a study that utilized the TMT and an fMRI to determine differences in brain activity across 36 healthy participants between the ages of 52 and 85 years old. Two TMTs were given, three trials of TMT-A and three trials of TMT-B, and data was collected on the speed and accuracy of which the participants completed each of the six trials. The replication is focused specifically on determining if there are neuroanatomical regions of the brain that show significantly different activity during the TMT-A and TMT-B, as well as if there was positive or negative activation in those areas. Significant group-level activation in brain regions during the TMT-A versus TMT-B was found using Python, and activation in those significant clusters during both tests was compared using a t-test. The replication yielded different t-statistics compared to the original study as slightly different significant clusters were analyzed. The hypothesis was that overall, both trail-making tests would show positive activation in regions of the brain involved with spatial learning, coordination, and memory retrieval when compared to group-level activation of the control condition. Moreover, since TMT-A and TMT-B require different cognitive skills, it was hypothesized that the TMT-B would show increased activation compared to TMT-A in regions of the brain dealing with task-switching and memory retrieval.

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Cover page of Distinct Representations of Subtraction and Multiplication in the Neural Systems for Numerosity and Language - A replication study

Distinct Representations of Subtraction and Multiplication in the Neural Systems for Numerosity and Language - A replication study

(2021)

A core paradox within cognitive science is the emergence of cultural functions, such as writing systems and arithmetic, that develop across time spans far too short for our neural systems to evolve to support them. Previous work has addressed this question with the neural recycling hypothesis, proposing that these newer functions are mapped onto pre-existing interconnected regions of the brain, called neural circuits. We replicated results from a study exploring the specific functions that have been recycled to allow for symbolic subtraction and multiplication. Original findings suggested that numerosity circuitry, typically responsible for comparing the size or quantity of two groups, is employed for subtraction and verbal processing circuitry for multiplication. We reviewed the collected fMRI data to construct a model of the brain with the region responsible for numerosity localized. We confirmed that the region localized by the numerosity task corresponded to the right intraparietal sulcus (IPS). Future research should focus on the corollary of the neural circuitry hypothesis—that later-evolving processes are subject to the restrictions of the circuitry they recycle. In particular, analyzing data obtained from incorrect answers to tasks would help confirm that recycling underlies the correlations we see between the neural activity of certain tasks.

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Cover page of Exploration of Subthreshold Beta-Amyloid Levels and Effects on Longitudinal Cognitive Function

Exploration of Subthreshold Beta-Amyloid Levels and Effects on Longitudinal Cognitive Function

(2021)

While there have been previous studies linking beta-amyloid accumulation in the positive range and cognitive decline, there has yet to be substantial research focusing on the significance of beta-amyloid accumulation in the negative range. The present study aims to replicate the findings of the original paper by Landau et al. 2018 which investigated potential associations between subthreshold levels of beta-amyloid accumulation and decreased executive or memory function. Utilizing data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI), longitudinal beta-amyloid accumulation from florbetapir-18 PET scan measurements in cognitively normal individuals and mild cognitively impaired was compared with longitudinal executive and memory function measurements. These findings will provide implications as to whether beta-amyloid accumulation in healthy, cognitively normal individuals may be an earlier indicator of cognitive decline.

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Cover page of All in a Day’s Laugh: A Replication and Extension of the Stress-Buffering Model of Positive Affect

All in a Day’s Laugh: A Replication and Extension of the Stress-Buffering Model of Positive Affect

(2021)

Positive affect, which is known to evoke pleasurable enegagement with one's environment, has well-established potential to reduce the negative effects of stress (Fredrickson, 1998). Although there are various facets of postive affect, we principally examined the alleviating effect of laughter--a common operational defintion of positive affect--on mental and physiological stress responses (Herring et al., 2011). We did so by conducting a replication and extension of a study published by Zander-Schellenberg et al. (2020), who affiirmed the stress-buffering effect of laughter frequency in daily life. In our replication, we attempted to reproduce the findings of the original study, conducted a residual analysis of the statistical models used, and assessed laughter-stress interplay across individual participants. In our extension, we assessed the cumulative stress-buffering effect of laughter frequency in daily life by determining whether the original findings apply to populations of varying daily aggregate laughter frequencies. Our replication results are consistent with the original findings, suggesting that laughter indeed attentuates negative consequences of stress. Interestingly, our extension results only showed this stress-buffering effect at play on days characterized by low daily aggregate laughter frequency. Possible implications of these results are discussed.

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Cover page of A Reversal of Roles: Effects of Visual Attention on Emotion. A replication of Attention drives emotion: Voluntary visual attention increases perceived emotional intensity.

A Reversal of Roles: Effects of Visual Attention on Emotion. A replication of Attention drives emotion: Voluntary visual attention increases perceived emotional intensity.

(2021)

Extant research has continually indicated that emotion moderates attention such that attention can be caught, maintained, and/or intensified towards a given emotional object (Mrkva, Westfall, & Van Boven, 2019). However, sparse research has investigated the reverse— whether attention can intensify emotion. To examine the bidirectionality of the relationship between emotional intensity and voluntary attention, we conducted a replication of the Mrkva et al. study on visual attention and emotional intensity. We hypothesized that participants would perceive target images as more emotionally intense than control images, and that their post-search ratings of emotional intensity for each target image would be higher than their pre-search ratings. Each participant was instructed to search for a specific image in a randomized sequence with varying emotional valence in separate trials per participant (Mrkva et al., 2019). Our primary outcome measures were the participants’ self-reported intensity of their emotional reaction to each image as well as their perception of the inherent emotional intensity of each image. Additionally, our secondary measures included ratings of the extent to which participants liked each image and how distinct they perceived the images to be. Our results ultimately supported our hypothesis, suggesting that directed attention towards an image enhances its perceived emotional intensity and distinctiveness. Examining whether attention can affect emotions poses practical significance, as it will allow us to better explore and understand how the objects that we pay attention to can impact our emotions in day-to-day life.

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Cover page of ‘Fairness Informs Social Decision Making in Infancy’ - Replication

‘Fairness Informs Social Decision Making in Infancy’ - Replication

(2021)

Fairness plays a significant role in children’s decision making and also carries meaningful social implications. In this study, our objective is to examine whether sensitivity to fairness develops before infants explicitly show fairness preferences. To further understand this, we replicated Lucca and Pospisil’s (2018) research to test whether infants (13- and 17- month-old infants) prefer to engage with individuals that exhibit fair or unfair behavior. In their study, infants were presented with a novel experimental paradigm in conjunction with video stimuli. Their results suggest that after infants witnessed an individual distribute goods to third parties equally and unequally, infants, both 13 month olds and 17 month olds,  actively chose to engage with individuals who distributed goods equally. Given their data, we completed statistical analyses and data manipulation techniques to identify any patterns about inclination towards fair or unfair actors. The Exact Binomial Statistical Test revealed statistical significance in data pertaining to both 13- and 17-month-olds between age and infant’s decision to socially engage with fair actors. Taken together, these findings are consistent with Lucca and Pospisil’s (2018) research. Infants demonstrate the expectation of fair distribution and prefer to interact with fair actors. This is important, as it gives greater insight into the timeline of fairness development over early years of life and may help explain behavior patterns seen during this age.

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Cover page of Evaluating the Effects of Fatigue-Induction on Mice’s Cognitive Behavior

Evaluating the Effects of Fatigue-Induction on Mice’s Cognitive Behavior

(2021)

Characterized as one of the most commonly distressing symptoms of cancer treatment, cancer-related fatigue (CRF) is reported to be more severe and persistent than “normal” fatigue. CRF has been shown to manifest in higher intensities and longer durations among cancer patients, impair mood and functional abilities, and, most relevantly, correlate with impairments in cognitive functioning, leading to impairments in other areas such as recognition memory and explicit memory. Despite its prevalence, CRF continues to be underreported and untreated due to a lack of information about the biological mechanisms underlying this symptom and its correlated impairments in cognitive systems. In order to uncover these mechanisms, the study conducted by Wolff, et. al. (2020) observed pelvic irradiation’s produced fatigue, and how it affects performance during various cognitive tasks, such as spontaneous altercations and reversal learning, as well as changes in whole-brain levels of mature and proBDNF. However, due to the possible behavioral confounds of the original study’s assessment of cognitive mechanisms and the inconclusive BDNF results presented, we aim to design a new list of cognitive tasks to more effectively assess cognitive impairments manifested after fatigue-induced pelvic irradiation. We hope that this new battery of cognitive tasks can aid future research attempting to specify the underlying cognitive mechanisms responsible for the cognitive impairments seen in cancer-related fatigue.

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Cover page of Experiential Stress and Physiological Stress: Implication of Coherence. A Replication and Extension Study

Experiential Stress and Physiological Stress: Implication of Coherence. A Replication and Extension Study

(2021)

The physiological response to stress and an individual’s subjective perception of stress are two systems vital to enabling adaptive responses to dangerous stimuli and maintaining individual well-being. When the body’s biological stress response and psychological interpretations of stress become misaligned, referred to as a low stress-heart rate coherence, detriments to health can occur (Sommerfeldt et al., 2019). Objective measures of physical stress, such as interleukin-6 and C-reactive protein, pro-inflammatory biomarkers of stress, and heart rate were analyzed in association with self-reported stress, measures of well-being, anxiety, and depression in a pool of Midlife participants from the United States. The present study utilized this data to replicate analyses performed by the original paper, “Individual Differences in the Association Between Subjective Stress and Heart Rate Are Related to Psychological and Physical Well-Being”. Preliminary findings from this effort indicate inconsistencies between standard statistical values due to missing data, however still illustrate a significant association between stress-heart rate coherence and wellbeing. We additionally attempted to explore the data further by running all statistical analyses for just white participants, hypothesizing that greater stress-heart rate coherence might be limited to this overrepresented demographic. We could not confirm nor deny the prediction, as we did not have access to full data to run analyses with minority data. In any case, all analyses yielded positive associations between individual well-being and stress heart-rate coherence, although further studies with more representative samples are imperative in understanding the generalizability and mechanisms for coherence.

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