Neuroscience and Neurobiology Commons^™

The Sensory Properties Of The Fast Visuomotor System, Rebecca Kozak

Electronic Thesis and Dissertation Repository

The brain has a remarkable capacity to rapidly transform vision into action, which allows us to initiate reaches towards targets within fractions of a second. Despite being fundamental to our interaction with a dynamic environment, these fast visuomotor transformations and their underlying neural substrates are poorly understood. This gap in the literature is further exacerbated by the unreliable presence of rapid visuomotor responses on the upper limb, likely due to the use of less optimal stimuli and paradigms. My thesis explores the stimulus properties which best evoke short latency reaction times and electromyographic responses during visually guided reaching, their application …

Motor Unit Firing Rate Control Of Agonist Skeletal Muscle During Voluntary Isometric And Shortening Contractions With Limb Movement, Eric A. Kirk

Electronic Thesis and Dissertation Repository

Voluntary movements throughout mammalian lifespan require skeletal muscle contractions that are controlled by time- and recruitment-dependent firing rate patterns. Single motor unit (MU) activity reflects the final efferent neural drive to the muscle, yet the underlying neural control of movement at the MU level is not well understood. Using intramuscular electromyography single MU recordings, relationships between voluntary contraction kinematics and MU firing rates were evaluated in vivo, in groups of young and older adult participants.

The purpose of study one was to characterize how MU firing rates are differently scaled among muscles relative to voluntary contraction intensity. Across 12 …

Assessment Of Intrinsic Hand Neuromuscular Physiology, Philemon Tsang

Electronic Thesis and Dissertation Repository

Alterations to the peripheral nervous system and neuromuscular physiology may impact hand function in a typical or clinical population, such as individuals with ulnar neuropathy. The mechanisms that influence these positive and negative changes are still not well understood. The three studies within my thesis aim to validate the reliability of decomposition-based quantitative electromyography (DQEMG) measurements and explore the changes in intrinsic hand neuromuscular physiology in a typical aging population and individuals recovering from a surgical intervention for severe ulnar neuropathy.

The purpose of the first study was to determine the test-retest reliability of near-fibre (NF) jiggle, a measure of …

Improving Stimulus Realism: The Effect Of Visual Dimension On Affective Responding, Shannon Compton

Electronic Thesis and Dissertation Repository

For decades researchers have used 2D stimuli under the assumption that they accurately represent real objects. This assumption has been challenged by recent vision and neuroeconomics research which has found that 2D images can evoke different neural and behavioural responses than real objects. The current study continues this line of research in the field of affective cognitive neuroscience; a field where small effect sizes are common and rapid habituation to affective stimuli used in the lab often occurs. The present study uses realistic 2D and 3D emotional images to determine the impact of visual dimension on affective responding. Subjective ratings …

Examining Motor Unit Stability Of First Dorsal Interosseous (Fdi) And Biceps Brachii (Bb) Muscles In Healthy And Older Adults Using Decomposition-Based Quantitative Electromyography (Dqemg), Igor Angelovski

Electronic Thesis and Dissertation Repository

Aging of the human neuromuscular system is associated with gradual decline in motor unit (MU) number leading to denervation of muscle fibers and subsequent compensatory reinnervation from surviving MUs. Lower limb muscles exhibit age-related increased MU instability (measured electrophysiologically), however not much is known regarding MU stability of aging upper limb muscles. The purpose of this study was to examine agerelated MU loss in upper limb muscles (first dorsal interosseous [FDI] and biceps brachii [BB]) and the impact on MU stability in younger and older healthy subjects using electrophysiological near fiber analysis from decomposition-based quantitative electromyography (DQEMG). FDI and BB …

Spatial And State-Dependent Effects Of Transcranial Magnetic Stimulation Of Prefrontal Cortex In Non-Human Primates, Chao Gu

Electronic Thesis and Dissertation Repository

The indirect effects of transcranial magnetic stimulation (TMS) within a distributed neural network are still largely unknown. Here we propose to use the non-human primate (NHP) oculomotor system as an animal model for investigating the effects of TMS. Across three animals, single pulses of TMS to the prefrontal cortex (PFC), including the frontal eye fields (FEF), reliably evoked a contralateral head turning synergy, similar to what is seen following intracortical microstimulation. Furthermore, double pulses of TMS paired with the memory-guided saccade paradigm only evoked neck muscle activity preceding contralateral saccades, showing similar state-dependency as previously observed in human TMS studies. …

When Faces "Feel" Familiar: The Role Of Affective Signals In Face Recognition, Lauren E. Dunphy

Electronic Thesis and Dissertation Repository

Previous research has suggested that there may be an increase in positive affect and autonomic arousal in response to seeing a familiar face. These studies rarely distinguish between faces for which there is only a “feeling” of familiarity, and faces for which this feeling is accompanied by the retrieval of semantic knowledge about the individual. In the current study we aimed to make that distinction. Participants made recognition judgments on famous and non-famous faces while galvanic skin responses (GSR), zygomatic muscle activity, and heart rate (HR) were recorded. We found increases in GSR (autonomic arousal), and zygomatic muscle activity (positive …