Neuroscience and Neurobiology Commons^™

Characterizing The Spatial Distribution Of Inhibitory Interneurons Across Early Sensory And Association Areas In Callithrix Jacchus, Nika Khajehdehi

Electronic Thesis and Dissertation Repository

The prefrontal cortex (PFC) is one of the cortical areas responsible for complex cognitive abilities, a function that is believed to arise from increased persistent activity within its microcircuits. Activity within microcircuits is regulated by parvalbumin-containing (PV), calbindin-containing (CB), and calretinin-containing (CR) inhibitory interneurons (INs). It remains unclear how the distribution of activity-regulating INs differs across cortical areas such that persistent activity increases specifically within association areas, allowing for their complex functions. This thesis aims to address this gap by characterizing the spatial distributions and differences in relative proportions of INs across early sensory areas and association areas of the …

Neural Dynamics Of Target Processing In Attentional Blink, Mansoure Jahanian

Electronic Thesis and Dissertation Repository

The attentional blink (AB) phenomenon refers to the failure to report the second target (T2) if it appears 200-500 ms after the first target (T1) in a stream of rapidly presented images. The present study aimed to investigate the neural representations of target processing under conditions where AB does or does not occur. We recorded EEG and behavioral data while participants viewed a rapid sequence of natural object images embedded with two face targets presented at two lag conditions: lag 3 (targets were 252 ms apart) and lag 7 (targets were 588 ms apart). Consistent with AB, our behavioral results …

The Impact Of Emotional Information On Task Performance In Unimodal Vs. Cross-Modal Paradigms, Emma K. Stewart

Electronic Thesis and Dissertation Repository

Emotional stimuli can disrupt or enhance task performance, and this may depend on the sensory modality involved. In unimodal paradigms (e.g. visual task-irrelevant stimuli during a visual task) emotional stimuli frequently produce distraction effects; it is unclear how emotion affects task performance in cross-modal paradigms (e.g. auditory stimuli during a visual task). This project explored task performance as a function of sensory modality and emotional valence. In Study 1, participants (N=50) completed a visual task in the presence of task-irrelevant negative and neutral images and sounds. Response times and accuracy were disrupted in the presence of visual but not auditory …

Using Meditation To Improve Measures Of Attention In Older Adults, Sabrina Ford

Electronic Thesis and Dissertation Repository

Age-related cognitive decline greatly impacts quality of life for older adults. Previous research has indicated that meditation may act as a neuroprotective factor to prevent age-related cognitive decline. This thesis sought to replicate previous findings and investigate if a four-week meditation intervention would improve sustained attention. Participants 60 years and older (n=27, 17 female) were recruited and assigned to a focused-attention (FA) meditation or relaxation group which met for four weeks, three times a week. Resting-state EEG was used to collect individual alpha peak frequency (iAPF) and frontal alpha asymmetry (FAA). The Sustained Attention to Response Task (SART) was also …

Relationship Among Neurogenic Orthostatic Hypotension, Cerebral Hemodynamics, And Cognitive Functioning, Lindsay Robinson

Electronic Thesis and Dissertation Repository

Neurogenic orthostatic hypotension (NOH) is characterized by a drop in systolic blood pressure ≥20mmHg or diastolic blood pressure ≥10mmHg within three minutes of upright posture. A large drop in blood pressure can trigger cerebral hypoperfusion, which has been linked to deficits in cognitive function. The current thesis aimed to measure cerebral hemodynamics and cognitive function in 20 NOH patients and 20 controls in the supine and head-up tilt (HUT) positions. Information processing speed (IPS) was assessed using the Symbol-Digit Modalities Test and attention was measured using the Stroop Test. NOH patients had significantly slower IPS in both the supine(p

Assessing Cognition In A Mouse Model Of Alzheimer’S Disease, Justin B. Mels

Electronic Thesis and Dissertation Repository

A major challenge in behavioural testing of Alzheimer’s disease (AD) mouse models is a low degree of standardization and translatability of tasks to humans. Bussey-Saksida touchscreen systems employ numerous tasks allowing for assessment of advanced cognitive function in mice using paradigms similar to those used in humans. This system can be used to assess cognitive deficits in dementia.

Our study focused on testing visual discrimination, cognitive flexibility and attention of the APP/PS1 familial AD mouse model longitudinally to assess behavioural changes related to cognitive decline. Surprisingly, APP/PS1 mice did not demonstrate impairments in the 5-Choice Serial Reaction Time Task, which …

Decoding Mental States After Severe Brain Injury, Raechelle M. Gibson

Electronic Thesis and Dissertation Repository

Some patients with disorders of consciousness retain sensory and cognitive abilities that are not apparent from their outward behaviour. It is crucial to identify and characterise these covert abilities for diagnosis, prognosis, and medical ethics. This thesis uses neuroimaging techniques to investigate cognitive preservation and awareness in patients who are behaviourally non-responsive due to acquired brain injuries. In the first chapter, a large sample of healthy volunteers, including experienced athletes and musicians, imagined actions of varying complexity and familiarity. Motor imagery involving certain complex, familiar actions correlated with a more robust sensorimotor rhythm. In the second chapter, several patients with …

Cognitive And Non-Cognitive Dysfunction In A Mouse Model Of Alzheimer's Disease, Wai-Jane V. Lee

Electronic Thesis and Dissertation Repository

Sensitive and translational tasks that efficiently and accurately assess cognitive function during pre-clinical trials would be useful in developing novel treatments for Alzheimer's disease (AD) patients. The Bussey-Saksida touchscreens employ various tasks similar to those used in humans to effectively evaluate high-level cognitive and executive functions in mice. This face validity provides the best chance of successful cognitive translation across species.

In our study, donepezil had minor effects on the performance of 5xFAD mice in the 5-CSRTT, a touchscreen task evaluating attention. Additionally, 5xFAD mice do not demonstrate impairments in the PVD task, which assesses visual discrimination/ cognitive flexibility. However, …

Pearls And Perils Of Pupillometry Using A Webcam, Mason Kadem, Rhodri Cusack

Undergraduate Honors Posters

Current methods to measure infants’ cognitive repertoire (i.e., collection of cognitive abilities) are limited. Previous testing paradigms required acquisition of non-age contextualized responses, and relied on measures that involved acquisition of other functions (e.g., language, motor). In addition to response limitations, cognitive functions may be difficult to observe in infants due to the difficulty in infant recruitment. Online testing has increased infant recruitment efforts and physiological responses have bypassed the motor, behavioural and linguistic limitations of infants. Recently, it has been shown that heart rate measures can be acquired through a webcam. Another feasible and reliable physiological measure is pupillometery, …

The Effects Of Concurrent Cognitive Load On The Processing Of Clear And Degraded Speech, Harrison Ritz

Electronic Thesis and Dissertation Repository

A previous study has found that perceiving degraded speech requires attention, with compromised behavioral and neurological measures of speech processing for degraded speech, but not clear speech, when participants are distracted (Wild et al., 2012b). We extended these findings by examining behavioral and neural correlates of speech perception under different levels of cognitive load using multiple object tracking. We also investigated the role of attention in perceiving degraded speech that was as intelligible as clear speech, in order to separate perceptual outcomes (i.e., intelligibility) from the requisite processing demands. We found that the speech perception system is heterogeneous in its …