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Pattern Component Modeling: A Flexible Approach For Understanding The Representational Structure Of Brain Activity Patterns, Jörn Diedrichsen, Atsushi Yokoi, Spencer A. Arbuckle

Brain and Mind Institute Researchers' Publications

Representational models specify how complex patterns of neural activity relate to visual stimuli, motor actions, or abstract thoughts. Here we review pattern component modeling (PCM), a practical Bayesian approach for evaluating such models. Similar to encoding models, PCM evaluates the ability of models to predict novel brain activity patterns. In contrast to encoding models, however, the activity of individual voxels across conditions (activity profiles) are not directly fitted. Rather, PCM integrates over all possible activity profiles and computes the marginal likelihood of the data under the activity profile distribution specified by the representational model. By using an analytical expression for …

Object Processing In The Medial Temporal Lobe: Influence Of Object Domain, Anna Blumenthal

Electronic Thesis and Dissertation Repository

We live in a rich visual world, surrounded by many different kinds of objects. While we may not often reflect on it, our ability to recognize what an object is, detect whether an object is familiar or novel, and bring to mind our general knowledge about an object, are all essential components of adaptive behavior. In this dissertation, I investigate the neural basis of object representations, focusing on medial temporal lobe (MTL) structures, namely, perirhinal cortex, parahippocampal cortex, and hippocampus. I use what type of thing an object is, or more specifically, the broader category (e.g., “face” or “house”) or …

The Role Of Human Primary Motor Cortex In The Production Of Skilled Finger Sequences, Atsushi Yokoi, Spencer A. Arbuckle, Jörn Diedrichsen

Brain and Mind Institute Researchers' Publications

Human primary motor cortex (M1) is essential for producing dexterous hand movements. Although distinct subpopulations of neurons are activated during single-finger movements, it remains unknown whetherM1also represents sequences of multiple finger movements. Using novel multivariate functional magnetic resonance imaging (fMRI) analysis techniques and combining evidence from both 3T and 7T fMRI data, we found that after 5 d of intense practice, premotor and parietal areas encoded the different movement sequences. There was little or no evidence for a sequence representation in M1. Instead, activity patterns in M1 could be fully explained by a linear combination of patterns for the constituent …

Evaluating Cognitive Impairment, Imaging And Blood Biomarkers In A Pre-Clinical Model Of Concussion, Brainscan, Western University, Arthur Brown, Marco Prado, Rob Bartha, Ravi Menon, Mark Daley

Project Summaries

The foundational milestone for the research, that we are addressing in this project, is to demonstrate that cognitive impairments in mouse models and humans are similar by using touchscreen technology. We will also be applying fMRI and MRS analyses to mouse models since they are analogous to that used in human studies - it will help us establish relevant endpoints for the studies as part of understanding the underlying characteristics, pathways and effects of concussion.

Imaging Fetal Brain Connectivity In High Risk Pregnancy, Brainscan, Western University, Sandrine De Ribaupierre, Barbara De Vrijer, Charles Mckenzie, Roy Eagleson, Simon Levin, Jacqueline Olgivie

Project Summaries

Our hypothesis is that differences in the regional connectivity within the fetal brain (the structural and functional connections between regions of the brain) can be observed with fetal fMRI as early as in the second trimester of pregnancy.

If we can detect differences in an at-risk fetal brain and associate that with plancental and maternal data, we could recommend interventions, such as diet or medication changes, and then monitor the impact of treatment on the fetal brain.

Development Of Fmri Compatible Reversible Deactivation To Examine Cerebral Networks, Brainscan , Western University, Stephen Lomber, Blake Butler, Stefan Everling, Blaine Chronik

Project Summaries

This study will permit us, for the first time, to examine the effects of deactivation of one cortical site on large-scale neural networks. It will permit neural networks to be functionally disassembled and the consequences of 'reversible' lesions, strokes or tumors to be assessed and modeled before they occur.

Relating Functional And Structural Signatures Of Parkinson’S Disease To Changes In Dopamine Signalling: A Pet/Fmri Study, Brainscan . Western University, Penny Macdonald, Udunna Anazodo, Justin Hicks, Frank Prato, Alain Dagher

Project Summaries

Cognitive impairments in early Parkinson's disease are known to be linked to complex changes in the dopamine system within the brain. For example, dopamine-producing neurons in one key region of the brain are significantly degenerated, but those in another are spared. Dopamine-replacement therapy (DRT) has been pursued and it has produced significant improvements in certain cognitive functions - unfortunately it also produced significant impairments in others.

The Impact Of Violent Gaming On The Brain As A Function Of Individual Differences In Trait Empathy, Brainscan , Western University, Derek Mitchell, Elizabeth Finger, Richard Neufeld

Project Summaries

In this project, we will uncover any existing interaction between violent media and the capacity for empathic reactions (known as trait empathy) at a neural level, as the foundational milestone for the kind of large-scale study discussed above.

The level of trait empathy varies by individual - we will explore whether exposure to violent media exacerbates the difficulties that those with low trait empathy already show in relating to the emotions of others

Assessing Listening With Engaging, Real-World Auditory Signals, Brainscan , Western University, Björn Herrmann, Ingrid Johnsrude 6612111

Project Summaries

Our project will develop and evaluate a novel way (using functional imaging, fMRI, and electrophysiology, EEG) to assess this cognitive impact of hearing loss with engaging, real‐world auditory stimuli. We will try to assess listening effort in more realistic listening situations among healthy listeners, comparing detected effort in degraded and clear acoustic conditions.

Using EEG, we will then develop measures that are sensitive to the cognitive demands imposed by degraded speech, using these features to assess hearing function with engaging narratives in natural listening conditions.

Ommaba: The Open Multimodal Music And Auditory Brain Archive, Brainscan , Western University, Jessica Grahn, Jorn Diedrichsen, Joe Gati, Molly Henry, Robert Zatorre, Jean-Baptiste Poline, Bratislav Misic, Estrid Jakobsen, Mor Regev, Marcel Farrés Franch, Virginia Penhune, Emily Coffey

Project Summaries

We will create a specific neuroimaging database focused on the auditory domain. It will allow researchers to ask questions about the neural circuitry underlying auditory behaviour in the healthy brain and to understand the sources of individual variability. We will include detailed information about experiential factors, such as musicianship and bilingualism that are not documented in any existing databases, so that it will be possible to investigate plasticity-related effects. It will also provide baseline data for clinical studies.

Development Of Virtual Gaming Environments For Functional Magnetic Resonance Imaging, Brainscan, Western University, Jody Culham, Ingrid Johnsrude, Julio Martinez-Trujillo

Project Summaries

The goal of this project is to develop, validate and test three aspects of a 3D video game environment for neuroscience.

Developing Behavioural Testing And Mr Imaging To Evaluate Cognitive Impairment In Models Of Cns Autoimmunity, Brainscan, Western University, Steven Kerfoot, Sarah Morrow, Ravi Menon, Flavio Beraldo

Project Summaries

This project will investigate cognition and cognitive fatigue in models of CNS autoimmunity. We will use automated touchscreens and fMRI to measure deficits in higher order brain functions.

We have two critical milestones in this project:

• to use touchscreen testing protocols to determine if mouse models demonstrate the same kinds of attention, working memory and cognitive fatigue deficits observed in MS, and
• to use fMRI to measure higher-order defects in the autoimmune models and identify any changes present that might be associated with cognitive dysfunction and the findings from human studies.

Disruption To Functional Networks In Neonates With Perinatal Brain Injury Predicts Motor Skills At 8 Months, Annika C Linke, Conor Wild, Leire Zubiaurre-Elorza, Charlotte Herzmann, Hester Duffy, Victor K Han, David S C Lee, Rhodri Cusack

Paediatrics Publications

Objective: Functional connectivity magnetic resonance imaging (fcMRI) of neonates with perinatal brain injury could improve prediction of motor impairment before symptoms manifest, and establish how early brain organization relates to subsequent development. This cohort study is the first to describe and quantitatively assess functional brain networks and their relation to later motor skills in neonates with a diverse range of perinatal brain injuries.

Methods: Infants (

Results: Disruption to connectivity of the somatomotor and frontoparietal executive networks predicted motor impairment at 4 and 8 months. This disruption in functional connectivity was not found to be driven by differences between clinical …

Persistent Post-Concussion Brain Changes In Adolescent Hockey Players, Brainscan, Western University, Kathryn Y. Manning, Amy Schranz, Robert Bartha, Gregory A. Dekaban, Christy Barreira, Arthur Brown, Lisa Fischer, Kevin Asem, Timothy J. Doherty, Douglas D. Fraser, Jeff Holmes, Ravi S. Menon

Research Summaries

Changes continue to occur in a concussed brain even after standard clinical tests have returned to normal. Damage in the very long fibre tracks in the brain of concussed players can be detected up to three months after the concussion and after the individuals have been approved for return to athletics. It is also possible to detect ‘hyper-connectivity’ in the brain, suggesting the brain is still trying to compensate for the concussion.

The Prefrontal Cortex And Obesity: A Health Neuroscience Perspective, Brainscan, Western University, Cassandra J. Lowe, Amy C. Reichelt, Peter A. Hall

Research Summaries

The level of activity within an individual’s prefrontal cortex seems to be critical to dietary self-control and the likelihood of overconsumption and obesity. Lower activity can make individuals more vulnerable to the appeal of calorie-rich foods. Sustained overconsumption and obesity can cause changes in the prefrontal cortex that further discourage dietary self-regulation, creating a reciprocal relationship that reinforces the poor dietary choices and encourages overconsumption.