McNair Research Journal - University of St. Thomas

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The University of St. Thomas McNair Research Journal Fall 2009 Volume 1 Table of Contents Letter from the McNair Scholars Program Director i Acknowledgements and McNair Program Staff ii Clemon J. Dabney, III 1 How Early Exposure to Light Changes Retinal Input to the Subcortical Visual System in the Albino Rat Aquanette Early 6 Systematic Labeling of African American Students: The influence of teacher’s perceptions on students expectations Reginald Evans 9 The Importance of Satire Ransom Fobanjong 12 Educating All Students: Culturally Responsive Teaching Christen J. Glass 18 Does Year in School Influence the Relationship Between Socioeconomic Status and Depression for College Students? Fushcia-Ann Hoover 23 A Comparison of Corn-Based Ethanol with Cellulosic Ethanol as Replacements for Petroleum-Based Fuels, A Review Paul L. Maitland-McKinley 28 Establishing a Definitive Model for Inflammatory Hypernociception in C57B1/6 Chinwe Obi 36 Nursing Student’s Reported Thinking During Medication Administration Maria Ortiz 43 Bridging the Gaps: Homeless Youth Services Aubrey Strenger 47 A Study of Mother-Son Relationships, Romantic Relationships, and Interpersonal Trust Mai Cha Vang 52 Trauma and Resilience: What we can learn from Naruto Amy S. Westmoreland 60 A Qualitative Analysis of Asian-American Attitudes Towards Interracial Romantic Relationships McNair Scholars Journal Publishing Agreement/Supplement Document 64
Humanities & Social Sciences How Early Exposure to Light Changes Retinal Input to the Subcortical Visual System in the Albino Rat Clemon J. Dabney III, Dr. J. Roxanne Prichard University of St. Thomas - Department of Psychology Abstract We observed the variation in retinofugal projections and c-FOS responses to light in retinorecipient nuclei of light-dark-reared (LD) and light-reared (LL) rats for 3 months; we also tested the affects of going from the LL group to the light-dark-reared (LLLD) group and from the LD group to a light-reared environment (LDLL) for 3 months; and compared them with the rats that had been in the LL or LD group for the whole experiment. The LD, LL, LDLL, LLLD groups were exposed to an hour of light then 18 hours of darkness. The rats were injected with anterograde tracer cholera-toxin (CT ) into the rats and quantified the density as well as the distribution of CT –stain in select regions of the subcortical visual system. Our research observed that LL had a significant increase in CT -stain in the ventral lateral geniculate nucleus (VLGN) and an increase in CT -stain that was approaching statistical significance in ventral lateral hypothalamus (VLH) and intergeniculate leaflet (IGL). These differences were decreased but not eliminated in the distribution of stain in the IGL and density of VLH when a switch to the LD happened at 3 months of age. The differences were increased by a switch to LD at 3 months in the VLGN group. The implications of this research study could play a critical role in understanding the development of the sensory nervous system. For most animals, their capacity to respond to differences in light is essential for their continued survival. Light is the external stimulus that cues the twenty-four hour circadian rhythm to the light-dark cycle; it activates seasonal and regulatory changes in both physiology and behavior. Light also acts to stimulate instantaneous changes in behavior; light can affect changes in vigilance. For example, darkness can promote sleep in diurnal creatures, whereas the opposite is true for nocturnal creatures. When the rat wakes up, when it eats and its motor activity are all inhibited by light (Borbely, Huston, & Waser, 1975). Changes in light stimuli as well as temperature can prompt seasonal adaptations in both behavior and physiology (Palchykova, Deboer, & Tobler, 2003). Early in an animal’s development photic stimuli has a significant influence on the timing of rapid eye movement (REM) sleep (Prichard, Fahy, Obermeyer, Behan & Benca, 2004). Sleep is essential for survival; it is a state that places an animal at an increased risk for predation, thus establishes significance to the timing of sleep. The amount of non-rapid eye movement (NREM) sleep, and REM sleep in each twenty-four hour day, as well as the amount of time spent awake is governed by homeostatic mechanisms. Franken’s research team found that sleep deprivation causes an enhanced EEG slow-wave activity and a reduced number of awakenings as well as an overall increase in the period of time spent asleep (Franken, Dijk, Tobler, & Borbely, 1991). The actual amount of time which an animal spends awake or asleep is determined by exchanges between the circadian rhythms, the sleep homeostat, and stimuli from the animal’s environment, which includes acute changes in light (Mrosovsky, Foster, & Salmon, 1999). There are separate anatomical systems which process visual stimuli. The primary visual system receives neuronal stimuli from the geniculocortical pathway. The geniculocortical pathway mediates the conscious visual perception of the primary visual system. The other the subcortical visual system mediates the unconscious responses to photic stimuli (Morin & Blanchard, 1999). There are two means discovered to date by which the subcortical visual system receives retinal input. One involves the rod-cone ospin system. This rod-cone ospin system includes specialized rod and University of St. Thomas McNair Research Journal Clemon J. Dabney III Early Light Exposure cone photoreceptor cells; these photoreceptor cells absorb light through rhodopsin and cone-opsins, light sensitive membrane proteins which deduce light energy into an electrochemical signal that is ultimately transmitted by neuronal cells to the visual cortex (Garriga & Manyosa, 2002). The other way in which the subcortical visual system receives retinal input is from a specific type of photosensitive melanopsin-containing retinal ganglion cell (Berson, 2003). The hypothalamic suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) are within the subcortical visual system and entrain the circadian responses to light. (Harrington, 1997; Moore & Eichler, 1976). The subcortical visual system entrains the circadian and acute responses to light as well as acute changes in behavioral state; the superior collicullus (SC) mediates compensatory and reflexive movements of the eyes, as well as the neck and head, and the pretectum (PT) mediates pupil dilation and constriction. The PT experiences an acute change in sleep patterns in response to light and dark stimuli in albino rats and is mediated by the subcortical visual system, and is regulated independently from cortical vision and circadian rhythms. The PT may regulate REM sleep in response to photic stimulus (Miller, Miller, Obermeyer, Behan, & Benca, 1999). The neurons of the olivary pretectal nuclei (OPN) receive photic stimuli and mediate the pupillary light reflex (Gamlin, Zhang & Clark, 1995). The IGL and ventral lateral geniculate nucleus (VLGN) seem to be very important in both photic and nonphotic phase shifting. The IGL and VLGN provide a mechanism for entrainment of circadian rhythms to a light-dark cycle. When the IGL and VLGN are ablated, a change in the phase shift responses to light pulses as well as responses of circadian rhythms to continuous light is observed (Harrington, 1997). The primary visual system needs early photic stimulation in order to function properly. This can be observed in the 1963 Wiesel and Hubel experiment, when kittens were deprived of sensory input to the eyes for the first three months of life there is a lack of photic stimuli to the primary visual system and thus a change in physiology, behavior and morphology. The lack of stimuli in the kittens led to extremely defective vision, in which visual placing and following reactions were not present, and it appeared that the kittens lacked the ability to perceive form (Wiesel & Hubel, 1963). This research as well as another research study led by the pair led to the findings that there is a critical period in the development of the primary visual cortex where, without proper stimuli, the process of synaptic refinement in the brain will not occur properly and the cat will have a significant reduction in visual acuity due to the visual stimuli deprivation. This observation is further seen in Hubel and Wiesel’s 1969 experiment that found that if an eye is closed for six days in the fourth and fifth week since birth the percentage of cells that the visually deprived eye can manipulate drops from 85 to 7% (Hubel & Wiesel, 1969). The early light environment of an animal has an affect on its later development. Canal-Corretger research study showed that differences in early lighting conditions have an effect on the circadian rhythm in rats; the lighting condition in which a rat was born and reared had a crucial impact on the future acute responses to light stimuli. Rats reared under constant bright light became arrhythmic and showed longer phases shifts; rats reared in constant darkness had shorter circadian rhythm phase shifts and were more responsive to photic stimuli. This may mean that the development of the circadian rhythm depends on the environmental stimuli as well as that the circadian system’s need to be developed before it can be influenced and manipulated by external stimuli like that of light (Canal-Corretger, Vilaplana, Cambras, & Noguera, 2001). 1
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