Matching Items (3)
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- All Subjects: Fluid Intelligence
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Description
Sensory gating is a process by which the nervous system preferentially admits stimuli that are important for the organism while filtering out those that may be meaningless. An optimal sensory gate cannot be static or inflexible, but rather plastic and informed by past experiences. Learning enables sensory gates to recognize stimuli that are emotionally salient and potentially predictive of positive or negative outcomes essential to survival. Olfaction is the only sensory modality in mammals where sensory inputs bypass conventional thalamic gating before entering higher emotional or cognitive brain regions. Thus, olfactory bulb circuits may have a heavier burden of sensory gating compared to other primary sensory circuits. How do the primary synapses in an olfactory system "learn"' in order to optimally gate or filter sensory stimuli? I hypothesize that centrifugal neuromodulator serotonin serves as a signaling mechanism by which primary olfactory circuits can experience learning informed sensory gating. To test my hypothesis, I conditioned genetically-modified mice using reward or fear olfactory-cued learning paradigms and used pharmacological, electrophysiological, immunohistochemical, and optical imaging approaches to assay changes in serotonin signaling or functional changes in primary olfactory circuits. My results indicate serotonin is a key mediator in the acquisition of olfactory fear memories through the activation of its type 2A receptors in the olfactory bulb. Functionally within the first synaptic relay of olfactory glomeruli, serotonin type 2A receptor activation decreases excitatory glutamatergic drive of olfactory sensory neurons through both presynaptic and postsynaptic mechanisms. I propose that serotonergic signaling decreases excitatory drive, thereby disconnecting olfactory sensory neurons from odor responses once information is learned and its behavioral significance is consolidated. I found that learning induced chronic changes in the density of serotonin fibers and receptors, which persisted in glomeruli encoding the conditioning odor. Such persistent changes could represent a sensory gate stabilized by memory. I hypothesize this ensures that the glomerulus encoding meaningful odors are much more sensitive to future serotonin signaling as such arousal cues arrive from centrifugal pathways originating in the dorsal raphe nucleus. The results advocate that a simple associative memory trace can be formed at primary sensory synapses to facilitate optimal sensory gating in mammalian olfaction.
ContributorsLi, Monica (Author) / Tyler, William J (Thesis advisor) / Smith, Brian H. (Thesis advisor) / Duch, Carsten (Committee member) / Neisewander, Janet (Committee member) / Vu, Eric (Committee member) / Arizona State University (Publisher)
Created2012
Description
Previous research has yielded an equivocal answer as to whether speaking aloud while performing intelligence tasks improves, impairs, or has no effect on performance. Some studies show that it impairs performance while others show it aids performance. In the studies in which speaking aloud has been shown to help, only children and older adults benefitted. The present study investigated whether college-aged students benefit from speaking aloud while performing a fluid intelligence test. Subjects performed a battery of working memory and intelligence tasks silently. Once they had completed each task, the participants took them again, though this time they spoke aloud while completing the tests. Results showed that subjects did insignificantly worse on the working memory tests when speaking aloud. However, subjects performed significantly better on the measures of fluid intelligence while speaking aloud as opposed to doing them silently. At an individual differences level, low working memory capacity participants benefited more from speaking aloud than the high working memory ones. Finally, we found a positive correlation between working memory scores and fluid intelligence scores, offering further evidence that the two constructs are related, yet different.
ContributorsRice, Z. Douglas (Author) / Brewer, Gene (Thesis director) / Duch, Carsten (Committee member) / Ball, Hunter (Committee member) / Barrett, The Honors College (Contributor) / College of Liberal Arts and Sciences (Contributor)
Created2012-12
Description
Working memory capacity and fluid intelligence are important predictors of performance in educational settings. Thus, understanding the processes underlying the relation between working memory capacity and fluid intelligence is important. Three large scale individual differences experiments were conducted to determine the mechanisms underlying the relation between working memory capacity and fluid intelligence. Experiments 1 and 2 were designed to assess whether individual differences in strategic behavior contribute to the variance shared between working memory capacity and fluid intelligence. In Experiment 3, competing theories for describing the underlying processes (cognitive vs. strategy) were evaluated in a comprehensive examination of potential underlying mechanisms. These data help inform existing theories about the mechanisms underlying the relation between WMC and gF. However, these data also indicate that the current theoretical model of the shared variance between WMC and gF would need to be revised to account for the data in Experiment 3. Possible sources of misfit are considered in the discussion along with a consideration of the theoretical implications of observing those relations in the Experiment 3 data.
ContributorsWingert, Kimberly Marie (Author) / Brewer, Gene A. (Thesis advisor) / McNamara, Danielle (Thesis advisor) / McClure, Samuel (Committee member) / Redick, Thomas (Committee member) / Arizona State University (Publisher)
Created2018