McDonald, Robert

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https://opus.uleth.ca/handle/10133/4740

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Browsing McDonald, Robert by Subject "Hippocampus"

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    Barriers to developing a valid rodent model of Alzheimer's disease: from behavioral analysis to etiological mechanisms
    (Frontiers Media, 2015) Gidyk, Darryl C.; Deibel, Scott H.; Hong, Nancy S.; McDonald, Robert J.
    Sporadic Alzheimer’s disease (AD) is the most prevalent form of age-related dementia. As such, great effort has been put forth to investigate the etiology, progression, and underlying mechanisms of the disease. Countless studies have been conducted, however, the details of this disease remain largely unknown. Rodent models provide opportunities to investigate certain aspects of AD that cannot be studied in humans. These animal models vary from study to study and have provided some insight, but no real advancements in the prevention or treatment of the disease. In this Hypothesis and Theory paper, we discuss what we perceive as barriers to impactful discovery in rodent AD research and we offer potential solutions for moving forward. Although no single model of AD is capable of providing the solution to the growing epidemic of the disease, we encourage a comprehensive approach that acknowledges the complex etiology of AD with the goal of enhancing the bidirectional translatability from bench to bedside and vice versa.
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    Context, emotion, and the strategic pursuit of goals: interactions among multiple brain systems controlling motivated behavior
    (Frontiers Media, 2012) Gruber, Aaron J.; McDonald, Robert J.
    Motivated behavior exhibits properties that change with experience and partially dissociate among a number of brain structures. Here, we review evidence from rodent experiments demonstrating that multiple brain systems acquire information in parallel and either cooperate or compete for behavioral control. We propose a conceptual model of systems interaction wherein a ventral emotional memory network involving ventral striatum (VS), amygdala, ventral hippocampus, and ventromedial prefrontal cortex triages behavioral responding to stimuli according to their associated affective outcomes. This system engages autonomic and postural responding (avoiding, ignoring, approaching) in accordance with associated stimulus valence (negative, neutral, positive), but does not engage particular operant responses. Rather, this emotional system suppresses or invigorates actions that are selected through competition between goal-directed control involving dorsomedial striatum (DMS) and habitual control involving dorsolateral striatum (DLS). The hippocampus provides contextual specificityto the emotional system, and provides an information rich input to the goal-directed system for navigation and discriminations involving ambiguous contexts, complex sensory configurations, or temporal ordering. The rapid acquisition and high capacity for episodic associations in the emotional system may unburden the more complex goal-directed system and reduce interference in the habit system from processing contingencies of neutral stimuli. Interactions among these systems likely involve inhibitory mechanisms and neuromodulation in the striatum to form a dominant response strategy. Innate traits, training methods, and task demands contribute to the nature of these interactions, which can include incidental learning in non-dominant systems. Addition of these features to reinforcement learning models of decision-makingmay better aligntheoretical predictions with behavioral and neural correlates in animals.