Psychology (Functional Area: Brain, Behaviour & Cognitive Sciences)

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Open Access
Comparing The Kinematics Of Grasping Vs. Placing In Humans
(2025-04-10) Por Davoody, Niousha; Crawford, John Douglas
While many studies have examined reach-to-grasp movements, the placement component remains less explored. Grasping and placing tasks share some common characteristics, such as precise localization and orientation of the hand, but differ in cognitive intent and sensory feedback, with grasping relying more on visual input and placing on somatosensory feedback relative to surroundings. This study employs a within-subjects 2x2x2 design, examining the effects of Task (grasp vs. place), Object Orientation (clockwise vs. counterclockwise), and Target Location (left vs. right) in right-handed participants performing in near-total darkness. Each participant completed 160 randomized trials across eight conditions, tracking hand and eye movements via an OptiTrack system and eye tracker. Results revealed significant main effects for Task, Location, and Orientation, along with notable interactions. Contrary to the hypothesis, placing tasks were faster than grasping tasks and exhibited higher orientation errors. This result contradicts the expectation that placement would require more precise alignment, suggesting that the simplified placement task used in this study may rely more on visual feedback, which was absent, compared to grasping. Movements toward the right showed faster velocities and fewer errors, reflecting hemispheric motor advantages, while clockwise orientations were associated with lower orientation errors compared to counterclockwise orientations. Interaction effects between Location and Orientation influenced certain variables, highlighting the role of spatial and alignment demands in motor control. These findings suggest that while grasping and placing tasks share overlapping motor control processes, they also engage distinct mechanisms under specific spatial conditions.
Open Access
Effects Of Tool Use And Perturbation During Motor Adaptation On Hand Localization In Immersive Virtual Reality
(2025-04-10) Khan, Maryum; Henriques, Denise
Our brain has a remarkable capacity for learning movements and adapting them to accomplish a motor goal. In many adaptation studies, participants move in a 2D plane while their hand is represented by a cursor. When visual feedback of hand position is misaligned, people can quickly compensate for this perturbation, show persistent reach aftereffects, and even misestimate the location of the unseen hand in the direction of previous visual training. However, it is unknown how well this generalizes to real-world settings or to the tools we use every day. Immersive virtual reality was used to test if end-effector shifts are also observed in more naturalistic virtual reality environments and if they extend to tools as end effectors. In the Hand Experiment, previous work from our lab was replicated where we found shifts in end-effector localization after adapting reach movements to a 30° and 60° visuomotor rotation of the hand, showing a similar magnitude of both shifts in where people indicate their perceived/felt hand and reach aftereffects following training to the perturbation in the VR environment. In the Pen Experiment, this paradigm was extended to investigate how well people can adapt when aiming with a common tool, like a pen, and whether the tool location is also recalibrated. The extent that the unseen location of hand-held tool, as well as the hand (in separate trials) recalibrates with adaptation was measured. Our results provide insight into the adaptative processes involved when learning to wield tools in more complicated, realistic environments.
Open Access
Sex-Related Differences In Visuomotor Skills, Cognition, And Emotionality Following Concussive Injury
(2025-04-10) Marks, CeAnn Alexia; Sergio, Lauren
Sex-related differences are commonly overlooked in most biomedical fields including concussion research. Much of the current concussion literature focuses on the analyses of males or a combined approach, lacking the separation of sexes for analytical purposes. Methods: Data were collected from 299 university athletes with varying concussion histories. Kinematic visuomotor measures and emotional symptoms were assessed through a basic visuomotor task and SCAT self-report measures. Results: Visuomotor performance varied substantially with concussion history and sex, with multiple concussions being linked to better performance. Emotionality results revealed females with 2 or more concussions have higher odds of being irritable, while 21-22-year-old females have lower odds of being nervous/anxious compared to their younger counterparts. No significant emotionality results were discovered for males. Conclusion: This study underscores distinctive recovery metrics between sexes in emotional and visuomotor domains following concussive injury. Findings suggest the need for tailored diagnostics and treatment for athletes following injury.
Open Access
Brain Responses To Symmetries In Naturalistic Novel Three-Dimensional Objects
(2025-04-10) Ragavaloo, Shenoa; Kohler, Peter
Human brains are sensitive to symmetry, especially vertical reflection, which is present in human faces and many other biological forms. However, symmetries in most visual scenes are rotated relative to the observer’s viewing location, failing to produce symmetry in the retinal image. We investigated the differences between perspective-distorted symmetry, and images that produce symmetry on the retina, and measured the association between responses to symmetry and autism spectrum disorder (ASD). We found that perspective-distorted symmetry with cues to 3D shape elicited responses, and both image-level and perspective distorted 3D symmetry elicited stronger responses than 2D symmetry. 3D image-level symmetry created stronger responses than 3D perspective-distorted symmetry. Lastly, there was no association between responses to symmetry and ASD. We conclude that symmetry processing occurs in the absence of a symmetry-related task, even for perspective-distorted symmetry. Additionally, there may not be any association between conditions that affect global processing and symmetry processing.
Open Access
Role(s) Of Pannexin1A/B In The Physiology Of The Zebrafish Visual System
(2025-04-10) Houshangi-Tabrizi, Sarah; Zoidl, Georg R.
Panx1 proteins are glycosylated integral membrane channels with unique conduction properties, functioning as an ATP channel and non-selective ion channel in different physiological pathways. In zebrafish, the mammalian Panx1 ohnologues, Panx1a and Panx1b, have distinct tissue expression patterns. We previously demonstrated that in the retina, Panx1a is localized in the horizontal cell layer and the ON/OFF ganglion cell layer, while Panx1b protein is present in the horizontal cell layer, ganglion cell layer, and in the end-feet of the Muller glia astrocytes. Here we investigated the optic flow response in the Panx1a-/- and Panx1b-/- 6dpf larvae utilizing molecular, systems, and behavioral assays. The RNA-seq analysis revealed broad regulation of genes involved in axon guidance, retinal axon guidance, astrocytes, axons, dendrites, and synapse, confirmed by RT-qPCR in the 3dpf and 6dpf Panx1a-/- and Panx1b-/-. We demonstrate that Panx1a-/- and Panx1b-/- display an inability to make a leftward and rightward directional motion in low light contrast conditions when exposed to the left and right moving gratings. We also show how the strategic localization of Panx1a and Panx1b in the habenula region modulates visually guided behavior. Lastly, Panx1a-/- and Panx1b-/- demonstrate the inability to generate functional saccades and display ocular motor deficiencies linked to potential neurological disorders. These findings suggest that Panx1 modulates the axonal growth in axon guidance pathfinding and together are interconnected to the habenula region, leading to synaptic plasticity of the retinal neural circuitry, and regulating visually guided locomotion in the zebrafish larvae.
Open Access
Realism and Features Supporting Lightness Constancy in Virtual Scenes
(2025-04-10) Patel, Khushbu Yogeshbhai; Murray, Richard F.
Lighting and surface properties play an important role in visual perception. Our visual system decodes two-dimensional retinal images to discern potential three-dimensional scenes. A particular challenge in the context of achromatic lights and surfaces is lightness constancy — the ability to maintain a consistent perception of an object’s reflectance despite varying illumination conditions. Although humans are generally adept at maintaining lightness constancy, it is not perfect. This dissertation examines lightness constancy within both real-world and virtual environments, including flat-panel displays and virtual reality (VR). Chapter 2 evaluates lightness constancy through an asymmetric lightness matching task across a shadow boundary, using physical surfaces, a flat-panel display, and an immersive VR environment. While the VR condition exhibited realistic levels of lightness constancy, participants showed significantly lower levels of constancy in flat-panel display compared to the physical environment. Notably, participant variability was more pronounced in both virtual environments. In Chapter 3 the study extends to lightness matching across various 3D orientations using both physical surfaces and in VR. The findings reveal that lightness constancy is significantly weaker in VR compared to physical environments. Building on Chapter 3, Chapter 4 further evaluates lightness constancy using the same task, but incorporates more realistic and accurate rendering techniques, along with realistic materials, in VR. Contrary to expectations, the results show no notable improvement in lightness constancy, underscoring the persistent challenges in achieving realism for tasks evaluating lightness across 3D orientations in VR. Despite robust 3D shape, lighting, and depth cues available in VR, constancy is significantly worse in VR and our understanding of lightness perception fails to explain why. This discrepancy highlights a gap in our knowledge, pointing to potentially overlooked factors critical for accurate lightness perception, such as fine material details or subtle surface textures. In conclusion, the findings in this dissertation suggest that VR is a reasonable proxy for real-world scenarios in tasks when lightness is judged across a shadow boundary, but current technology falls short in replicating realistic lightness constancy when image luminance varies from one location to another due to differences in 3D orientation relative to a light source.
Open Access
Examining Eye Movements In Response To Repeated Exposure To Building Stimuli
(2025-04-10) Yerkeyev, Maxym Sergiyovy; Freud, Erez
Research has consistently indicated a strong connection between eye movements and memory processes. This thesis explores this relationship by examining how repeated exposure to AI-generated images of buildings influences eye movements and memory. Twenty-four participants viewed 120 building images across four levels of repetition (novel, once, three, and five times), while their eye movements were recorded, and their memory assessed. The results showed significant repetition effects on both eye movements and memory. Eye movement measures revealed a decrease in fixation count and saccadic amplitude, and an increase in fixation duration, with increased repetitions. Memory measures revealed improved recognition and confidence, with increased repetitions. These repetition effects align with previous studies on faces and scenes, suggesting that the effects supersede differences in how specific object categories are processed. Overall, this thesis demonstrates that memory and oculomotor systems are associated in processing buildings, just as they are in processing faces and scenes.
Open Access
Factors in Perceptual Shape Completion
(2025-04-10) Chosang, Tenzin; Elder, James H.
Humans rely on bounding contours to segment scenes and recognize objects in our 3D world, despite the challenge of occlusions that partially block objects in the visual field. Our ability to perceptually complete these occluded contours, filling in missing fragments, plays a crucial role in object recognition. Previous research has assessed local and global methods for shape completion based on their objective accuracy, but not in relation to human perceptual completion. In this thesis, observers viewed partially erased bounding contours, simulating occlusion, and adjusted the position of a dot along a virtual line where the contour would likely continue. The missing intervals ranged from 10% to 50% of the total shape. Analysis of objective error and bias revealed that humans use more than local cues in shape completion, indicating a complex integration of information to perceptually restore missing contours.
Open Access
The Perception Of Falling Objects
(2024-11-07) Phan, Mai Huong; Harris, Laurence
Aristotle believed that objects fell at a constant velocity, which raised the possibility that people's visual perception of falling motion might be biased away from acceleration towards constant velocity. I tested this idea by requiring participants to judge whether a ball moving in a simulated naturalistic setting appeared to accelerate or decelerate, as a function of its motion direction and the amount of acceleration/deceleration. I found that the point of subjective constant velocity (PSCV) differed between up and down but not between left and right motion directions, which indicated that more acceleration was needed for a downward-falling object to appear at constant velocity than for an upward “falling” object. I found no significant differences in sensitivity to acceleration for the different motion directions. My results support the idea that Aristotle's belief may in part be due to a bias that reduces the perceived magnitude of acceleration for falling objects.
Open Access
The Contribution of Cortical Feature Processing to Oculomotor Target Selection
(2024-03-16) Kehoe, Devin William Heinze; Murray, Richard; Fallah, Mazyar
We effortlessly move our eyes to objects with specific features and avoid objects with other features. This feature-guided target selection behavior has been studied extensively in experimental psychology and systems neuroscience. By now, the visual and cognitive factors that mediate target selection and the neural signatures of target selection in oculomotor substrates are clear. For example, neural activation encoding targets and distractors gradually divergences over time therefore signalling stimulus identity, while visual/cognitive factors like bottom-up salience or top-down priority modulate the precise time of this divergence. But despite the extensive research on oculomotor target selection, little research has examined how neural activation in oculomotor substrates encoding potential eye movements vectors is reweighted to indicate stimulus identity. Meanwhile, a parallel branch of systems neuroscience has thoroughly examined the function and anatomy of the visual processing pipeline distributed throughout the neocortex of mammals. Heretofore, however, there has been little if any attempt to characterize the relationship between cortical visual feature processing and oculomotor vector encoding during feature-guided target selection. This dissertation presents a series of behavioral experiments that provide several insights into this relationship. In these experiments, I measure the perturbation of target-directed saccades elicited by competitive remote distractors as a function of (1) the feature-space distance between targets and distractors and/or (2) distractor processing time. Given the close correspondence between saccade perturbation metrics and the underlying physiology of the oculomotor system, this methodology offers a non-invasive analog to examining the time course of oculomotor distractor activation during feature-guided target selection. In one set of experiments, I observed that distractor activation encodes the feature-space distance between targets and distractors in a manner consistent with attentional pruning of visual features observed in cortical feature representations during feature-based attentional deployment. In another set of experiments, I observed that the pattern of visual onset response latencies across distractor features mimics the pattern robustly observed between the cortical modules specialized for processing the respective features. These results indicate a close representational and temporal parity between feature encoding in oculomotor and (cortical) perceptual systems. I therefore propose a broad theory of oculomotor feature encoding whereby eye movement vectors in oculomotor substrates are dynamically and continuously reweighted by the feature-dependent network of cortical modules in the perceptual system necessary for representing the relevant feature set of the potential eye movement target.
Open Access
Examining the Effects of Real-World Experience on Lab-Based Scene Memory
(2023-12-08) Orlando, Maria Sara; Rosenbaum, Shayna
Boundary extension (BE) is as an error in scene memory, such that participants retrieve details beyond the given boundaries of a scene image. Boundary contraction (BC) is the opposite effect, whereby participants retrieve less context within the boundaries of a given scene image. Some research supports the view that BE reflects (re)construction of the scene from an internal representation that was formed, whereas other research supports the view that BE (and BC) emerge from image-based properties. This study tested the influence of familiarity on scene recognition through the comparison of lab-based encoding of images of pre-experimentally familiar (real-world) places with images of unfamiliar places. There was a tendency for BC across both image conditions, with evidence of maintained, and an instance of greater, BC for familiar than unfamiliar scene images. Importantly, the lack of evidence for increased BE with greater familiarity favours an image-based theoretical account of BE and BC.
Open Access
Modelling the Effects of Demographics and Lifestyle on Cognitive Performance
(2023-12-08) Park, Sarah Victoria Sanhua; Henriques, Denise
Human cognitive performance is ultimately the result of many factors. Previous inquiries note the contributions of demographic and lifestyle cognitive performance. I used a series of structural equation models and dimensionality reduction methods to identify how demographic and lifestyle measures simultaneously contribute to cognitive performance: a theory-driven model using combined measures of cognitive performance and latent variable structure; and a data- driven model using principal components analysis. Participants (N = 1141, Mage = 23.13 years) completed a battery of tasks and questionnaires measuring cognitive performance and collecting demographic and lifestyle measures. Overall, both models provided evidence that the inclusion of lifestyle measures over and above demographic measures accounted for and predicted cognitive performance. Further, the two models give rise to complementary but distinct insights into the basic components of cognitive performance. This work provides a methodology and evidence for accounting for difference in cognitive performance with demographic and lifestyle measures.
Open Access
Investigating neuromodulation with theta burst stimulation to primary visual cortex and subsequent effects on resting state networks: A multi-echo fMRI study
(2023-12-08) Cohan, Remy; Steeves, Jennifer
Theta burst stimulation (TBS) is a type of rTMS protocol which has the advantage of a shorter delivery time over traditional rTMS. When applied to motor cortex, intermittent TBS (iTBS) has been shown to yield excitatory aftereffects, whereas continuous TBS (cTBS) may lead to inhibitory aftereffects, both lasting from minutes to hours. The majority of TBS research has targeted motor and non-motor frontal areas of the brain, and to date very few studies have examined its efficacy at visual areas. In a sham-controlled study we investigated the immediate poststimulation and short-term (1 h post-stimulation) effects of iTBS and cTBS to V1.
Open Access
Examining Cognitive-Motor Integration, Persistent Symptoms, and Brain Function in Individuals with Concussion
(2023-12-08) Ozzoude, Miracle Ebelechukwu; Sergio, Lauren E.
In everyday life we interact with our environment in an indirect way, where there is a mapping between the viewed goal of our action and the required movement (e.g., using a computer mouse). Such tasks require cognitive-motor integration (CMI), where rules dictate the relationship between perception and action. The underlying CMI control networks that rely on intact frontal, parietal, and subcortical brain region connectivity may be compromised following concussion, resulting in an impaired ability to engage in complex movements. Here we investigate whether such relationships also exist in working-aged adults with persistent post-concussion symptoms (PPCS). Methods: Twenty-two individuals (5 males) performed two visuomotor tasks: one requiring direct (standard) interaction with visual targets, and one comprising a plane-change and feedback reversal (non-standard interaction) between viewed target and required hand motion (CMI). PPCS and dizziness were related to brain network function via resting state functional connectivity (RSFC) in six networks and structural integrity via cortical thickness in CMI-related brain regions and white matter tracts via diffusion tensor imaging. Results: We observed that lower cortical thickness in the inferior and superior parietal cortices were associated with dizziness and impaired non-standard visuomotor performance, respectively. Furthermore, higher PPCS severity was associated with hyperconnectivity within the visual, sensorimotor control, frontoparietal control, and dorsal attention networks, whilst hyperconnectivity within the salience ventral attention network was associated with higher non-standard visuomotor performance. Lastly, we found that lower white matter tract integrity in several long associative, projection, and commissural tracts were associated with lower visuomotor performance, PPCS severity, and dizziness. Conclusions: These findings characterise the impact of PPCS on the structure and function underlying impaired visuomotor performance, and suggest that CMI may be a non-invasive, easily accessible tool for brain network function assessment in those affected by concussion.
Open Access
Did The Pandemic Lockdowns Affect The Welfare of The Sumatran Orangutans (Pongo abelii) At The Toronto Zoo?
(2023-12-08) Gading, Ezekiel Franco; MacDonald, Suzanne
The COVID-19 pandemic led to unprecedented lockdowns with rippling impacts on the lives of humans and animals alike. Fortunately, these lockdowns also presented the opportunity to study the relationship of visitor presence with the welfare of zoo-housed animals as natural experiments. The reduction of visitor counts to zero for several consecutive months allowed researchers to study visitor effects on welfare measures and address the confounding variables associated with the time of the day. The purpose of this thesis was to study how the welfare measures of the Toronto Zoo Sumatran orangutans (Pongo abelii) changed when visitors were reintroduced after the lockdowns were lifted. I compared behavioural and physiological measures of stress between the lockdown and visitor introduction phases. Specifically, I studied changes in aversive behaviour by measuring the equality of physical enclosure space use, as well as changes in behavioural indicators of arousal (self-directed behaviours, agonistic behaviours, and object-directed displacement) and a physiological indicator of arousal (fecal consistency) as visitors were reintroduced to the orangutan pavilion. I found that the orangutans did not change their space use when visitors were introduced. In fact, the orangutans hid less when visitors were introduced than during the lockdown. This suggests that visitor presence was not aversive to these orangutans. Foraging and inactivity levels did not change across the phases of the study. Behavioural indicators of arousal also did not change when visitors were introduced. Fecal consistency did not change across the study. However, the presence of conspecifics and keepers strongly affected the behaviours of the orangutans. The results are congruent with studies that found that the pandemic lockdown measures did not negatively affect the welfare of a variety of species.
Open Access
Factors Impacting the Time Course of Visuomotor Reach Adaptation
(2023-08-04) Ruttle, Jennifer Elizabeth; Henriques, Denise
Reaching with altered visual feedback leads to adaptation of internal motor plans, which result in aftereffects, deviated reaching without visual feedback, and proprioceptive recalibration, a shift in perceived hand location (Cressman & Henriques, 2010). However, the rate or speed by which these implicit motor and sensory changes emerge and how this timecourse may be affected by the quality of the feedback during training has yet to be investigated. In a series of experiments, I looked at the speed and size of implicit changes, specifically reach aftereffects and shifts in felt hand position, how fast they emerge and how they vary as a function of the quality of error signals and certainty of the rotation during training. In the first experiment, participants had full access to error signals during training with altered visual feedback of their hand, and during this training, reach aftereffects, and active and passive hand localizations were measured after every single reach-training trial. This gave us a baseline of how fast these implicit components shifted during ‘classic’ training. Shifts in felt hand position reached saturation within one trial and reach aftereffects also reached saturation within three trials of visuomotor rotation training which is much faster than previously believed. In the second experiment we reduced error signal information during training by removing the hand cursor until the reach movement was complete or by constraining hand movements along a channel, so the cursor always went straight to the target. The goal was to investigate if and to what extent these error signals affected the timecourse of proprioceptive recalibration. Despite this reduction, we could not detect a decrease in the rate or size of shifts in felt hand position, indicating the robustness and invariance of these visually-induced changes in proprioceptive estimates. In the third and final experiment, we reduced certainty in the rotation by changing it every 12 trials and still measured estimates of felt hand position on a trial-by-trial basis. We once again found shifts in felt hand position in the expected size and direction that peaked just as fast as the previous experiments, indicating that proprioceptive recalibration is a consistent aspect of reach adaptation to altered visual feedback. The rapid speed by which saturation is attained may also suggest that shifts in proprioceptive recalibration may be a driving factor in reach adaptation, as it saturates far earlier than adaptation does.
Open Access
Visuomotor Learning and Proprioception Across Development
(2023-03-28) Clayton, Holly Ann; Henriques, Denise
Being able to adapt our motor repertoire to novel contexts is crucial for completing even the simplest daily tasks. This can be examined in visuomotor adaptation paradigms where the motor system is challenged to compensate for changes in vision, such as learning to reach to targets on a screen with a misaligned hand-cursor, which our brains do through trial-and-error. A motor command is sent to the arm and a prediction of the outcome is sent back into the brain. This prediction is compared with sensory feedback from proprioceptors and is thought to generate one of the error signals that drives motor learning. This begs the question of whether adaptation processes might differ across development if proprioception is less reliable, as proprioceptive impairments have been found to occur alongside normal aging (children and older adults differ from young adults) and in several neurological disorders. Proprioception is suspected to be impaired in Ehlers-Danlos syndrome (EDS), a group of inherited connective tissue diseases where the most common symptoms are joint hypermobility and chronic pain. In Chapter 2 I explored sensitivity of hand proprioception in EDS as a function of disease severity. In Chapter 3 I further explored proprioceptive sensitivity in EDS by comparing patients’ estimates of hand position to those of controls, and changes in their estimates after participants underwent visuomotor adaptation. Finally, in Chapter 4, I examined whether visuomotor adaptation differs across the lifespan, by looking at several characteristics of learning and comparing them across groups of children, young adults, and older adults that I tested in familiar settings. Together, these findings provide further insight into how the sensorimotor system functions under special developmental circumstances, such as with connective tissue disease, or during early/late stages of life.
Open Access
Differentiating Visual Search Efficiencies for Symmetry Type and Texture Regularity
(2023-03-28) Moreau, Rachel Carmen Earleen; Kohler, Peter
Symmetry is believed to be a fundamental gestalt that aides in our day-to-day ability to interact with the visual world. The goal of this thesis was to investigate the differential processing of types of symmetry when embedded in texture or when viewed as individual objects. Across four experiments, I used the behavioural paradigm of the visual search task to measure processing efficiency across types of symmetry and texture regularity. I used stimuli called “wallpaper groups” which allowed for manipulations of symmetry type while holding constant low and midlevel visual cues. My results indicated that reflection symmetry was processed more efficiently than rotation symmetry and when these symmetries are embedded in a regular texture, they are processed more efficiently than not. The results of this research extend previous findings across behavioural psychology and visual neuroscience.
Open Access
Sex and Sexual Orientation Differences in Perceptual and Cognitive Processing
(2023-03-28) Andrinopoulos, Katerina Deanna; Steeves, Jennifer
Sex differences have been found in some visual perception and cognitive abilities, and male and female brains have been shown to have differences in functional activation. These abilities include mental rotation, face recognition and face detection. One way to measure mental rotation is by using the mental rotation task (MRT), with males outperforming females (Voyer, 2011). Face perception tasks show differences favouring females (McBain et al., 2009; Brewster et al., 2012). Same-sex attracted males tend to perform at the level of females in face recognition ability (Brewster et al., 2012). This thesis seeks to further examine the effect sexual orientation has on these visual and perceptual abilities that have previously shown sex differences. A male advantage was found for mental rotation ability, with heterosexual males outperforming heterosexual females. Within the same-sex attracted groups, this difference was not found, with same-sex attracted females performing at the level of same-sex attracted males.
Open Access
Effects of the Brain Derived Neurotrophic Factor Val66met Polymorphism on the Structural and Functional Architecture of the Human Brain
(2022-12-14) Alba Suarez, Vicente Alejandro; Stevens, Dale
Brain Derived Neurotrophic Factor (BDNF) is an important neurotrophin enabling synaptogenesis at the dendrites of neurons. Several studies have implicated the Val66Met single nucleotide polymorphism of the BDNF gene as a factor affecting cortical thickness and resting-state functional connectivity (RSFC) of the human brain. In this thesis, I investigated the effects of Val66Met on cortical thickness and RSFC among individual cortical regions and at the level of large-scale functional networks in all genotype groups (Val/Val, Val/Met, Met/Met, and Met carriers). Cutting-edge techniques were used to individually localize anatomical and functional brain regions in a large sample of healthy young adults from the Human Connectome Project. A comprehensive series of analyses revealed no significant group differences in cortical thickness or RSFC across the brain. These results suggest that, contrary to previous reports, the Met allele does not confer differences in structural or functional integrity of the healthy young adult brain.