Includes bibliographies. / Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1977. / Microfiche copy available in the Institute Archives and Barker Engineering Library. / by William Mark Rabinowitz. / Ph.D.

Alpha- and beta-tectorin (Tecta and Tectb) are major non-collagenous components of the tectorial membrane (TM). The presence of a zona pellucida (ZP) domain in both tectorins suggests that Tecta and Tectb can form hetero- or homopolymers. It is unclear, however, how these proteins assemble to form the TM matrix. The mechanisms of apical targeting, secretion and processing of the tectorins are also unexplored. I used fluorescently-tagged tectorin constructs for stable transfection into polarised epithelial MDCK cells or transient expression in mouse cochlear cultures to develop an in vitro model of TM matrix assembly. Significant amounts of matrix were not observed with stable tectorin expression in monolayer cultures of MDCK cells. In contrast, I observed substantial amounts of dense extracellular matrix on the apical surfaces of outgrowth zone cells when cochlear cultures were transiently transfected with either Tecta or Tectb. When ectopically expressed in hair cells, Tecta and Tectb locate to the distal tips of the hair bundle. To study the role of the inner-ear protein Ceacam16 in hearing, we generated a Ceacam16 functional null mouse model. The Ceacam16 gene was inactivated by targeted replacement of exons 2-5 with the bacterial lacZ gene. β-gal staining I performed reveals that Ceacam16 is expressed in the epithelial cells of the spiral limbus and inner sulcus, and in both the pillar cells and Deiter's cells. I first detected the presence of Ceacam16 in the TM at P12, four days before the defined striated-sheet matrix is observed. Transmission electron microscopy reveals a complete loss of striated-sheet matrix in Ceacam16 null mice in comparison to the wild-type. The results of this thesis suggest neonatal mouse cochlear cultures as a model for studying tectorin-based extracellular matrix production and also reveal that Ceacam16 is required for normal formation and/or maintenance of striated-sheet matrix.

The current training model for paraeducators traditionally consists of single-day workshops, emails, newsletters, in-service meetings or other similarly isolated and infrequent tips or no training at all. Such practices have caused many paraeducators and teachers to cite a lack of efficient and effective training as one of the major difficulties in their job. The purpose of the study was to establish a causal relationship between the independent variable: the direct instruction of precorrection through modeling and guided practice with bug-in-the-ear feedback and the dependent variable, the performance or nonperformance of positive behavior support strategies in the classroom. The study took place at an urban middle school located in northern Utah. The study's three participants were paraeducators who worked in a self-contained classroom for students with severe disabilities. The intervention consisted of a three-phase lesson for each of the three target skills: (a) a training phase, (b) an independent phase, and (c) a follow up phase. Data indicate a positive functional relation between the intervention and the acquisition and maintenance of the desired skills. On average, participants performed more than 90% of the steps of the desired behaviors across all phases of the intervention and maintained the skills over time in a natural setting after relatively little instruction, no additional time outside of the classroom, and with materials already available at most schools. The success of this training model and its flexible framework further suggest that its use could be expanded in multitudinous ways. As this is the first known study of its kind, there are now numerous avenues of new research possibilities both in the area of paraeducator training, but also teacher training and even training in other work industries. This is an exciting new avenue for research and the improvement of working conditions and the delivery of instruction in schools.

Introduction: Hearing loss affects over 500 million people worldwide and results from irreversible damage to inner ear hair cells. The only available treatment is cochlear implants, which may be unable to provide sensory input if neuronal connections are lost, as they are in mouse models. Thus, regeneration of hair cells offers the only permanent cure; however, such therapeutic intervention requires a detailed molecular understanding inner ear development and hair cell maintenance. During mouse development, there is a balance between proliferation and differentiation that not only determines the size of the ear, but also is needed to form a functional sensory unit. The fulcrum to this balance is N-Myc, a key transcription factor that acts as a node incorporating many upstream growth signaling pathways and funnels them to directly alter the cell cycle and at the same time inhibits differentiation. The loss of N-Myc results in major morphogenetic abnormalities, including a progressive loss of cochlear, despite their initial formation. Interestingly, N-Myc is present in inner ear hair cells after birth, long after proliferation in the inner ear ceased. In addition to N-Myc, L-Myc is co-expressed throughout development in the inner ear. This data suggests that N-Myc and L-Myc may play partially redundant roles both early during development and later in hair cells. Elucidating the relative importance of the Mycs and their interdependent roles in maintaining the balance between proliferation and differentiation may shed light on future hair cell regeneration avenues. Methods: We generated two Cre-LoxP lines, knocking out both N-Myc and L-Myc before (Pax2-Cre) and after (Atoh1-Cre) hair cell formation. We assessed the possibility of Myc redundancy through 3D reconstructions generated from confocal image stacks from E10.5-E18.5 and the effects of early Myc loss on the balance between proliferation and differentiation through a quantitative PCR study that assessed relative changes in gene expression, using the Pax2-Cre N-Myc f/f L-Myc f/f mice. We assessed organ of Corti development and functionality at P21 and four months of age in the Atoh1-Cre N-Myc f/f L-Myc f/f mice. Results: The development of the Pax2-Cre N-Myc f/f L-Myc f/f mutant ear was more severely impacted than the Pax2-Cre N-Myc f/f alone, as shown by an additional 50% reduction in size. Genes important to cell cycle maintenance were downregulated whereas differentiation transcription factors were initially downregulated but subsequently later upregulated to normal levels. In Atoh1-Cre N-Myc f/f L-Myc f/f mice, there were no defects in hair cell development. Discussion: There appears to be redundancy between N-Myc and L-Myc with N-Myc playing a more important role in inner ear formation. The late-onset defects seen in the Pax2-Cre N-Myc f/f mice appear to be a result of abnormal formation of hair cells due to the disruption in the balance between proliferation and differentiation much earlier on. This is the first time such a late-onset hair cell loss has been shown to be due to a defect sustained much earlier and is an important finding as the majority of people suffer from late-onset hearing loss. Additionally, these findings highlight the continued therapeutic importance in elucidating the molecular interactions controlling the delicate shift from a proliferating precursor to a differentiating cell.

The middle ear system is a vital component in the propagation mechanism of otoacoustic emissions. As such, investigation of the effect of variation in middle ear impedance on the measurement of emissions is warranted. Distortion product otoacoustic emissions (DPOAEs) have gained recognition as a means of gaining frequency specific information on auditory function. As the effects of changes in middle ear impedance will vary as a function of frequency, a clear definition of the relationship between middle ear impedance and DPOAE amplitude across the frequency spectrum is needed. Twenty adults (ages 20-37) with normal hearing and normal middle ear function were selected as subjects. Commercially available equipment (Virtual 330) was used to measure the DPOAEs on all subjects. The unit was modified to change canal pressure by coupling the probe to the pressure pump of a clinical acoustic immittance system. One ear from each subject was randomly selected for measurement and each subject was tested under five pressure conditions: +200, O, -200, -300, -400 daPa. The mean frequency of the fl/f2 tone pairs swept from 500 to 8000 Hz. Results indicate that changes in ear canal pressure can effect the amplitude of DPOAEs. Alteration of ear canal pressure resulted in decreased emission amplitude. This effect was found to differ as a function of eliciting frequency with the greatest reduction in amplitude with the mean of the primaries at 500 Hz. Less variation was noted across the ear canal pressures with the higher frequency stimuli. These results are consistent with previous findings reported regarding the effects of impedance changes on spontaneous and transiently evoked otoacoustic emissions.

Prior to this investigation, there appeared to be no published research data available on tympanometric configurations obtained from an older adult population. This study was designed to examine tympanograms obtained from an otologically normal, elderly population. Forty individuals, ranging in age from 59 to 83 years, participated in this study. All had a negative history of middle ear pathology and had normal tympanic membranes as determined by otologic examination. From the eighty ears tested, fifty were used in this survey. Conductance and susceptance at 220 and 660 Hz were obtained at each ear and ranges for admittance were computed from these components. Additionally, acoustic reflex thresholds were obtained from this population. The results obtained indicate that the values for the measures of conductance and susceptance are comparable to those from young adult groups. The reflex thresholds are slightly higher in the older group because their hearing thresholds are not as acute as those found in younger populations. Finally a larger percentage of the older population than might be expected was found to have evidence of healed perforations which were not discovered during otoscopic examination. The present investigation demonstrated that additional normative data are neededin order that the otoadmittance meter be fully utilized with older adult populations.

Objetivou-se por meio deste trabalho identificar a existência de expressões faciais e corporais que refletem o estado emocional de bezerros de raças leiteiras. Foram estudados 32 bezerros com idades entre 1 e 8 semanas durante quatro dias. Foram formados 8 grupos com 4 animais cada, de forma aleatória, formando grupos homogêneos entre si em idade. Cada grupo foi analisado duas vezes. Os animais foram levados a uma câmara de teste com laterais abertas e coberta com telha metálica, sobre uma área de pastagem, onde receberam a aplicação dos tratamentos \"estímulo positivo afago\" e \"estímulo negativo teste do guarda-chuva\". A expressão facial foi analisada por meio das unidades de ação facial sobrancelha, boca, narina e área da esclera ocular. A expressão corporal foi verificada por meio das variáveis posição de orelha e posição de cauda. Os animais foram avaliados durante seis tempos experimentais: ambiente natural, pré-teste, teste, pós-teste 1, pós-teste 2 e ambiente natural após teste. Ambos os estímulos provocaram redução (p < 0,05) da área de esclera ocular de 3,50 cm2 para 1,10 cm2, e da área de narina de 8,58 cm2 para 6,07 cm2. A sobrancelha levantada esteve presente durante o estímulo negativo (p > 0,05). Não foi possível identificar se as modificações nas unidades de ação facial foram decorrentes de emoções positivas ou negativas. Toda manipulação com os animais provocou alteração nas unidades faciais. O posicionamento de orelha e cauda estão relacionados a emoções positivas e negativas. A posição de orelha \"para atrás\" e a posição de cauda \"arqueada\" estão associadas a expressão de emoções positivas. A posição de orelha \"horizontal\" e a posição de cauda \"presa\", a emoções negativas. Os tipos de posições de orelha e cauda são indicadores de estado emocional positivo ou negativo em bezerros, e há um grande potencial para o uso dessas medidas para mensurá-lo. Assim, identificamos a existência de expressões faciais, com a variável sobrancelha, e corporais, com a posição de orelha \"para atrás\" e cauda \"arqueada\" que refletem estados emocionais positivos; e posição de orelha \"horizontal\" e cauda \"presa\" que refletem estados emocionais negativos em bezerros. / The purpose of this research was to identify the existence of facial and body expressions that reflects the emotional state of dairy calves. Thirty-two calves between 1 and 8 weeks of age were studied for four consecutive days. Eight groups with four animals each were formed randomly, forming homogeneous groups among themselves in age. Each group was analyzed twice. The animals were taken to a test chamber with open sides and covered with metal tile over a pasture area, where they received the application of the treatments positive \"neck stroking\" and negative \"umbrella test\" (Sandem et al. 2004). The facial expression was analyzed through the facial action units: eyebrow, mouth, nostril and eye white. Body expression was verified by the ear position and tail position variables. The animals were evaluated during six experimental times: natural environment, pre-test, test, post-test 1, post-test 2 and natural environment after the test. Both stimuli caused reduction (p < 0,05) in eye white area from 3,50 cm2 to 1,10 cm2, and area of nostril from 8,58 cm2 to 6,07 cm2. The raised eyebrow was present during the negative stimulus. It was not possible to identify if the changes in facial action units were due to positive or negative emotions. All manipulation with the animals caused a change in the facial units. The positioning of ear and tail are related to positive and negative emotions. The \"back\" ear position and the \"arched\" tail position are associated with expressing positive emotions. The \"horizontal\" ear position and the \"between hindlimbs\" tail position, to negative emotions. The types of ear and tail positions are indicators of positive or negative emotional state in calves, and there is great potential for using these measures to evaluate emotions. Thus, we identified the existence of facial expressions, with the variable eyebrow, and body expression, with the position of \"back\" ear and \"arched\" tail that reflects positive emotional states; and \"horizontal\" ear position and \"between hindlimbs\" tail reflecting negative emotional states in calves.

Abstract not available

Damage to one vestibular apparatus (unilateral vestibular deafferentation, UVD) results in severe postural and ocular motor disturbances (such as spontaneous nystagmus, SN) that recover over time in a process known as vestibular compensation. However, the underlying neurochemical mechanisms of vestibular compensation are poorly understood. While UVD affects many areas in the CNS, attention has focused upon the partially deafferented second order neurons in the vestibular nuclei complex (VNC). Several converging lines of evidence suggest that Ca�⁺-permeable ion channels (N-methyl-D-aspartate receptors and L-type voltage-gated Ca�⁺-channels) and intracellular Ca�⁺-dependent protein kinases play an important role in vestibular compensation. However, the nature of this involvement and the locus of these changes are unknown. The aim of this thesis was to investigate the role of Ca�⁺ signalling pathways in the VNC during vestibular compensation in guinea pig. These issues were investigated in three separate experiments that utilised two methodological approaches: i) in vitro assays were used to determine the nature and extent of protein phosphorylation within the VNC at various stages of compensation; and ii) ion channel blockers or cell-permeable kinase inhibitors were injected directly into the VNC immediately before UVD to determine whether or not these systems were causally involved in compensation. The results of experiment 1 (Chapter 5) showed that a bolus intra-VNC injection of an uncompetitive NMDA receptor antagonist, but not an L-type voltage-gated Ca�⁺ channel antagonist, temporarily reduced SN frequency at the earliest measurement time (6 hours post-UVD). These results suggested that the initial expression of SN required, in part, the activation of NMDA receptors in the VNC on the side of the UVD, and by inference, Ca�⁺ entry through the ion channel. The results of experiment 2 (Chapter 6) revealed that the medial VNC contains abundant Ca�⁺/calmodulin-dependent and Ca�⁺/phospholipid-dependent protein kinase activities. The same VNC tissue removed from animals at various times after UVD, showed that vestibular compensation is accompanied by specific changes in the phosphorylation of several major protein kinase C substrates. These included an unidentified 46-kDa band, and a 75-kDa band with similar characteristics to the myristoylated alanine-rich C kinase substrate (MARCKS). These results suggest that protein kinase C signalling pathways may be involved in vestibular compensation. The results of experiment 3 (Chapter 7) are consistent with these results showing that intra-VNC infusion of a protein kinase C inhibitor, but not a Ca�⁺/calmodulin-dependent protein kinase II inhibitor, significantly increased SN at the earliest measurement times (6 and 8 hours), but had no effect upon the time taken to achieve compensation or on postural compensation. These results suggest that the induction of SN compensation involves protein kinase C activity in the VNC. Taken together, these findings suggest that the mechanisms underlying the expression of SN (e.g., Ca�⁺ influx via NMDA receptors) are possibly distinct from those that initiate its compensation (e.g., PKC activation). The downstream effects of raised intracellular Ca�⁺ may involve protein kinase C-dependent phosphorylation of key intracellular proteins that initiate long-lasting changes in cellular function within the VNC.

Loss of sensory input from one vestibular labyrinth by unilateral vestibular deafferentation (UVD) results in a severe ocular motor (i.e., spontaneous nystagmus (SN)) and postural syndrome (i.e., yaw head tilt, (YHT) and roll head tilt (RHT)) which compensates over time in a behavioural recovery process known as vestibular compensation. It is generally accepted that the UVD-induced neuronal imbalance in the resting activity between the two vestibular nuclear complexes (VNCs) generates the ocular motor and postural syndrome and that the restoration of the resting activity in the ipsilateral VNC plays a causal role in the compensation of the static symptoms. γ-Aminobutyric acid (GABA) and the GABAA and GABAB receptors within the VNC are involved in normal vestibulo-ocular and --spinal pathways and it has been suggested that modification of GABAergic inhibition may be a mechanism responsible for the recovery of resting activity in the ipsilateral VNC. Behavioural, western blotting, and immunoassay techniques were used to address the role of the GABAA receptor in the VNC during vestibular compensation. The first study involved the characterization of SN, YHT, and RHT compensation in guinea pigs that had been anaesthetized with isoflurane during the UVD. These animals compensated rapidly (i.e., 30 hrs) and the time to compensate was independent of the duration of the anaesthesia. Using the 30 hrs time frame, the effects of the chronic infusion of the GABAA receptor agonist (muscimol) / antagonist (gabazine) into either the ipsilateral or the contralateral VNC on the compensation of SN, YHT, and RHT, were determined. Infusion of muscimol (250, 500, and 750 ng) into the contralateral VNC and gabazine (31.25, 62.5 and 125 ng) into the ipsilateral VNC significantly affected YHT and RHT (p < 0.05), but not their rate of compensation (p > 0.05). Interestingly, the effects of muscimol and gabazine on YHT and RHT were consistent throughout the first 30 hrs post-UVD. At 30 hrs post-UVD, the pumps were disconnected. In both experimental groups, the value and direction of the YHT and RHT returned to vehicle levels. Infusion of muscimol (62.5, 125, and 250 ng) into the ipsilateral VNC and gabazine (125, 375, and 750 ng) into the contralateral VNC had little effect on YHT and RHT, or their rate of compensation. At 30 hrs post-UVD, the pumps were disconnected. In both experimental groups, the value and direction of the YHT and RHT returned to vehicle levels. These results suggest that the ipsilateral gabazine and contralateral muscimol infusions were modifying the expression of the symptoms without altering the mechanism of compensation. Furthermore, the mechanism responsible for vestibular compensation can cope with the both the GABAA receptor-mediated and the UVD-induced decrease in resting activity. Results from the western blotting study indicated that compensation of SN, YHT, and RHT is not associated with changes in the protein levels of the GABAA receptor α₁, β₂, or γ₂ subunits. Compensation of SN, YHT, and RHT is associated with an elevation in cortisol salivary levels. Overall, the results suggest that the GABAA receptors are involved in the expression of YHT and RHT, but not in the mechanism that is responsible for their compensation.