Neuroscience and Neurobiology Commons^™

Reaching For The Light: The Prioritization Of Conspicuous Visual Stimuli For Reflexive Target-Directed Reaching, Daniel K. Wood

Electronic Thesis and Dissertation Repository

The degree to which something stands out against the background of its environment communicates important information. The phenomenon of camouflage is a testament of the degree to which visual salience and probability of survival tend to overlap. Salient stimuli often elicit fast, reflexive movements in order to catch prey or avoid a predator. The overarching goal of the work presented in this thesis is to investigate how the physical salience of visual stimuli influence the programming and execution of reaching movements. I approached this question by recording kinematics and muscle responses during reaching movements. Broadly, this thesis investigates the effect …

Testing The Template Hypothesis Of Vocal Learning In Songbirds., Adriana Diez

Electronic Thesis and Dissertation Repository

The auditory forebrain regions NCM and CMM of songbirds are associated with perception and complex auditory processing. Expression of the immediate-early gene ZENK varies in response to different sounds. Two hypotheses are proposed for this. First, ZENK may reflect access to a representation of song memories. Second, ZENK may reflect attention. I tested these hypotheses by measuring ZENK in response to tutored heterospecific or isolate songs compared to non-tutored wild-type song. Young zebra finch females were exposed to different tutoring conditions and later exposed to different playbacks, and the expression of ZENK in CMM and NCM measured. ZENK responses varied …

Cognitive Roles Of Anterior And Posterior Pedunculopontine Tegmentum Subregions, Jordan C. Robinson

Electronic Thesis and Dissertation Repository

The pedunculopontine tegmentum (PPT) is part of the mesopontine cholinergic system with distinct anterior and posterior subdivisions. With fast sensory input and descending connections to brainstem locomotor centers, we predict posterior PPT (pPPT) mediates prepulse inhibition of acoustic startle reflex, a form of sensorimotor gating that affects attentional processes. Similar to pPPT cholinergic projections to ventral tegmental area, we predict anterior PPT cholinergic input to substantia nigra regulates dopamine release in striatum, which is important for reinforcement learning. We lesioned the PPT bilaterally in male Sprague Dawley rats with ibotenic acid. Posterior cholinergic cell loss was significantly correlated with prepulse …

Exploring The Neural Basis Of Top-Down Guided Action In Macaque Monkeys, Jessica M. Phillips

Electronic Thesis and Dissertation Repository

To thoroughly characterize any brain mechanism requires an appropriate animal model for invasive studies. An invaluable model system used toward a comprehension of cognitive neurophysiology is the macaque monkey. It is important to delineate similarities and limitations for this model in relation to the human brain and cognition. In this thesis, we have thus conducted three experiments to investigate putative generalizations between monkeys and humans regarding the neural processes associated with top-down action control in monkeys.

Our daily behaviour is largely comprised of automatic routine actions. The frequent repetition of certain behaviours in response to particular contexts can give rise …