<p> Animal studies have shown that the tonotopic organization of the auditory cortex is not statically fixed, but can be remodeled by experience. The purpose of this study was to investigate whether or not frequency discrimination training can induce changes in the cortical representation of a selected frequency in humans. Six human subjects were trained for approximately 3 weeks to detect a change in pitch between two tones (40Hz amplitude modulated) using a standard frequency of 2040 Hz. Each subject was tested on his/her discriminative ability before and after training using three different standards (2040Hz, 1840Hz, and 2240Hz). EEG data were recorded both before and after training and changes in transient and steady-state responses were investigated. Behaviourally, every subject improved at the discrimination task using the trained frequency. However, only three subjects demonstrated transfer to both untrained frequencies. In the EEG data, the P2-Nl amplitude increased in five of the six subjects and the Nllatency decreased in all six for the 2040Hz set. These two findings were statistically significant (p<0.05) for the group. There were no statistically significant findings for the side frequencies. The change in the 40 Hz steady-state response was also not significant, increasing in three subjects and decreasing in the other three. These findings indicate that changes are expressed in the secondary auditory cortex. These findings may also be applicable to the treatment of tinnitus. </p> / Thesis / Master of Science (MSc)

Two experiments were designed to evaluate human sensitivity to elasticity. Elastic objects bend when a force is applied to them. Observers saw two computer-generated bending rods (defined by the motions of 50 dots) on any given trial and were required to judge which rod was more flexible. Elasticity difference thresholds were calculated for each observer for each of three bending conditions. The rods bent in a plane that was either frontoparallel or oriented 42.5 or 85 degrees from frontoparallel. The results showed that observers could precisely discriminate between bending rods of different elasticities, independent of whether the bendings occurred in the frontoparallel plane or in depth. To rule out the possibility that the ability to judge bending motion was based on the ability to judge 2-dimensional (2-D) speed a second experiment was conducted to obtain difference thresholds for 2-D speed. The observers' speed discrimination thresholds were not positively correlated with their elasticity discrimination thresholds, which suggests that the observers' ability to judge bending motion was not based on their capability to discriminate differences in speed.

Phonological processing, the ability to recognize and manipulate the sounds of one's native language, is an essential linguistic skill. Deficits in this skill may lead to decreased social, educational, and financial success (Kraus & White-Schwoch, 2019). Additionally, phonological disorders have been shown to be highly variable and individualized (Bellon-Harn & Cradeur-Pampolina, 2016) and therefore difficult to treat effectively. A better understanding of the neural underpinnings of phonological processing, including the underlying skill of phonemic discrimination, could lead to the development of more individualized and effective intervention. Several studies, some using quantitative electroencephalography (qEEG) and others using functional magnetic resonance imaging (fMRI), have been conducted to investigate these neural underpinnings. When considering the relative strengths and weaknesses of qEEG and fMRI, the scientific community has traditionally believed qEEG to be excellent at determining when brain activity occurs (temporal resolution), but to have limited abilities in determining where it occurs (spatial resolution). On the other hand, the reverse is believed to be true for fMRI. However, the spatial resolution of qEEG has improved over recent decades and some studies have reached levels of specificity comparable to fMRI. This thesis provides an abbreviated meta-analysis determining the accuracy and consistency of source references, or areas where brain activation is determined to originate from, in qEEG studies evaluating phonemic discrimination. Nineteen experiments were analyzed using the Comprehensive Meta-Analysis software. A study's event rate was defined as the number of times an anatomical area was coded as a source reference, divided by the participants in the study. Results show that each of these experiments had relatively low event rates, culminating into a summary event rate of 0.240. This indicates that qEEG does not provide source references that are as accurate or consistent as fMRI. This meta-analysis concludes that although there is research suggesting qEEG may have developed to be comparable to fMRI in spatial resolution, this is not supported in the analysis of qEEG studies focused on phonemic discrimination.

AN ABSTRACT OF THE THESIS OF Ousmane Sawadogo, for the Master of Arts degree in Applied Linguistics and TESOL, presented on May 4, 2015, at Southern Illinois University Carbondale. TITLE: PERCEPTION OF /q/ IN THE ARABIC /q/-/k/ CONTRAST BY NATIVE SPEAKERS OF AMERICAN ENGLISH: A DISCRIMINATION TASK MAJOR PROFESSOR: Dr. Soo Jung Chang Studies on speech perception have suggested that non-native sound perception is influenced by the listener’s native language. Non-native sound contrast perception depends on a given sound’s similarity or dissimilarity to the listener’s equivalent native language sound. The Perceptual Assimilation Model (PAM) posits that it is difficult to distinguish non-native sounds when they are perceived as very similar to native sounds and are thus assimilated to a native sound category, but identification is easier when the non-native is sound is dissimilar to a native sound (Best, 1994a). The present study investigated whether native speakers of American English would display very good discrimination of /q/ in the Arabic /q/-/k/ contrast as predicted by the PAM. The Speech Learning Model (SLM) posits that non-native perception is position-sensitive and hypothesizes that the listener’s perception of non-native sounds would vary from one position to another (Flege, 1995). The current study also aimed to investigate whether the discrimination of the Arabic /q/-/k/ contrast would be position-sensitive. The current study also investigated the effect of the vocalic context on the discrimination of /q/. Participants consisted of 22 (6 male and 16 female) native speakers of American English who were students or faculty members at Southern Illinois University. Their ages ranged between 19 and over 50. The data were collected through an online AXB discrimination task survey. Target sounds were represented in 108 pseudowords so that the sounds could be contrasted in minimal pairs. The environments were word-initially followed by /i/, /u/, and /a/; word-medially, between two instances of /i/, two instances of /u/, and two instances of /a/; and word-finally, preceded by /i/, /u/, and /a/. Two pseudoword pairs were selected for each contrast. Four AXB combinations (AAB, ABB, BAA, and BBA) were generated for each of the nine contrasts, which resulted in a total of 36 stimuli. The participants were requested to click on a button to listen to the recordings of these word pairs and check the right answer. The findings were consistent with predictions made by PAM that native speakers of American English would have a very good discrimination of /q/ in the Arabic /q/-/k/ contrast. The results suggested that the uncategorized versus categorized (UC) type could also be of excellent discriminability. SLM was not totally supported because the differences were not statistically significant. However, the data indicated that some positions resulted in better discrimination scores than other positions and that certain vowels likewise resulted in better vocalic discrimination scores. Keywords: Discrimination task, non-native sound perception, Arabic /q/-/k/ contrast, position-sensitive, context-sensitive, vocalic context, UC type assimilation, Speech Leaning Model (SLM), Perceptual Assimilation Model (PAM).

Chez les rongeurs, la mémoire procédurale est préservée alors que la mémoire « déclarative » est profondément altérée au cours du vieillissement normal ou pathologique.L’injection d’un agoniste partiel des récepteurs 5-HT4 (SL 65.0155. 0.01mg/kg) permet aux rongeurs de récupérer leurs facultés dans une tâche de discrimination olfactive, le labyrinthe olfactif par exemple.L’activation des récepteurs 5-HT4 par un agoniste pourrait être utilisée pour lutter contre les dysfonctionnements mnésiques rencontrés dans certaines pathologies neurodégénératives telle que la maladie d’Alzheimer. L’injection d’un agoniste partiel des récepteurs 5-HT4 (SL 65.0155. 0.01mg/kg) permet aux rongeurs de récupérer leurs facultés dans une tâche de discrimination olfactive, le labyrinthe olfactif par exemple.L’activation des récepteurs 5-HT4 par un agoniste pourrait être utilisée pour lutter contre les dysfonctionnements nésiques rencontrés dans certaines pathologies neurodégénératives telle que la maladie d’Alzheimer. / In normal aging or pathological brain diseases in rodents procedural memory is spared while reference memory is deeply impaired.Injection of a partial selective 5-HT4 agonist (SL65.0155. 0.01mg/kg) enabled complete recovery of association learning performance in an olfactory associative discrimination task, the olfactory tubing maze for exemple.Activation of 5-HT4 receptors by a selective agonist could be useful for the symptomatic treatment of memory dysfunctions related to pathological aging such as Alzheimer’disease.

<p>  </p> <p><em>Syngap1+/-</em> is a mouse mode for intellectual disability and autism spectrum disorder where haploinsufficiency of the <em>Syngap1</em> gene and therefore downregulation of SynGAP1 leads to early maturation of synapses within the brain within post-natal days fourteen and sixteen instead of at the normal developmental schedule of post-natal day thirty. This early-shifted timeline falls directly before the visual critical where binocular matching between inputs from the two eyes occurs, and during a period where neurons become selective to specific orientations. High-level visual and cognitive issues observed in autism spectrum disorder patients might follow from deficits in basic sensory processing development, but it is not yet understand how <em>Syngap1</em> haploinsufficiency affects visual development and visual processing. Therefore, to characterize visual processing within the <em>Syngap1+/-</em> mouse model of autism spectrum disorder, acute electrophysiological recordings were performed within the monocular and binocular regions of the mouse visual cortex (V1). Responses to a series of visual stimuli were analyzed to measure and compare receptive field size, orientation selectivity, and binocularity between <em>Syngap1+/-</em> mice and littermate controls. In order to understand how potential deficits in physiology could translate into visual perception, a behavioral training protocol was implemented which isolated visual acuity in mice. In accordance with known developmental timelines in the visual cortex, it was found that the receptive field sizes of V1 neurons in <em>Syngap1+/-</em> mice were unchanged from wild type controls. However, these same neurons had wider tuning curves and lower firing rates than neurons in littermate controls. Ocular dominance was unaltered between <em>Syngap1+/-</em> and wild type mice, but this was possibly due to low sample sizes of neurons from the binocular regions of V1. At the behavioral level, lower visual acuities were discovered in <em>Syngap1+/-</em> mice with a size degree difference compared to littermate controls – a minor but significant difference. These results indicate a reduction in SynGAP1 expression has a perceivable effect on V1 development and function at both physiological and behavioral levels.</p>

No / Auditory signals have been shown to exert a marked influence on visual perception in a wide range of tasks. However, the mechanisms of these interactions are, at present, poorly understood. Here we present a series of experiments where a temporal cue within the auditory domain can significantly affect the localisation of a moving visual target. To investigate the mechanism of this interaction, we first modulated the spatial positional uncertainty of the visual target by varying its size. When visual positional uncertainty was low (small target size), auditory signals had little or no influence on perceived visual location. However, with increasing visual uncertainty (larger target sizes), auditory signals exerted a significantly greater influence on perceived visual location. We then altered the temporal profile of the auditory signal by modulating the spread of its Gaussian temporal envelope. Introducing this temporal uncertainty to the auditory signal greatly reduced its effect on visual localisation judgements. These findings support the view that the relative uncertainty in individual sensory domains governs the perceptual outcome of multisensory integration.

This thesis focuses on various factors affecting effectiveness of aposematic signals against avian predators. Adult, wild-caught as well as hand-reared juvenile great tits (Parus major) were used as predators in the experiments. The thesis consists of the following four studies. In the first study, we compared the reactions of great tits from two geographically distant populations toward aposematic firebugs (Pyrrhocoris apterus) and their non-aposematic artificially made colour variant. The birds from the Bohemian population mostly avoided aposematic firebugs and attacked non-aposematic variant. Finnish birds, which lacked experience with firebugs from their natural environment, were less hesitant to attack both firebug colour forms. Although the Bohemian birds avoided the aposematic prey variant, they were not more neophobic than Finnish birds. We conclude that the geographic differences in reactions of the birds to aposematic prey can be explained by a different population-specific experience of the birds with local aposematic prey communities. In the second study, we compared effectiveness of two chemical defence strategies in leaf beetle larvae (Chrysomela lapponica) against great tits. The birds avoided larvae devoid of external secretions after the first attack, which indicates the presence...

This study examines the perception of Mandarin lexical tones by native speakers of Greek who are naïve to Mandarin. Being able to discriminate between Mandarin lexical tones is essential for effective and accurate communication in the language. While there is an increasing number of research studying the perception of Mandarin tone by speakers from various backgrounds, the Greek language has not received much attention. By employing an AXB discrimination task, this study tested the perception of Mandarin tone pairs T1-T2, T1-T4, and T2-T3 by native speakers of Greek. Due to their acoustic similarity, these three pairs are often found to be the most confusing tone contrasts for non-native listeners of Mandarin. Greek speakers (NG) had the highest accuracy for T1-T2 (0.88), and similar accuracy rates for T1-T4 (0.83) and T2-T3 (0.82). Subsequently, the Greek speakers were divided into two groups based on their experience with learning or playing a musical instrument, as this is a factor that has been shown to affect tone perception. Compared to non-musicians (NG1), the group of musicians (NG2) had higher accuracy rates for T1-T2 and T1-T4, and a similar accuracy rate for T2-T3. For NG1, from easiest to hardest, the accuracy rates were: T1-T2(0.93)&gt;T1-T4(0.92)&gt;T2-T3(0.82). For NG2, the accuracy rates were: T2-T3(0.82)≥T1-T2(0.82)&gt;T1-T4(0.74). These findings could improve our understanding in regard to the factors that can affect the perception of Mandarin lexical tone by native Greek speakers, which might contribute to language pedagogy. / 本论文旨在研究以零基础普通话希腊语母语人士对普通话声调范畴的感 知能力。为了进行有效和准确的研究，本文实施了普通话发音辨别实验。虽 然声调范畴感知能力的研究越来越多，但以希腊语母语者为研究对象的研究 并不多见。通过 AXB 发音辨别测试，本论文调查了希腊语为母语的人士对普 通话 T1-T2、T1-T4、T2-T3 三组声调组合的辨识感知。由于声音的相似性， 这三对声调组合对非普通话母语的听众经常被发现是最容易被混淆的。结果 发现，讲希腊语的人士（NG）对这三组声调组合辨识的准确度为：T1-T2 （0.88）是最高的，T1-T4（0.83）和 T2-T3（0.82）是相似的。有研究认为 音乐训练可以影响对声调的感知，所以接着实验参与者根据学习或演奏乐器 的经验又被分成两组。与非音乐背景人群（NG1）相比，有音乐背景人群 （NG2）T1-T2 和 T1-T4 的准确率更高，但对 T2-T3 组合的结果是一样的。若 从最简单到最难排序，有音乐背景人群（NG1）的准确度是：T1-T2 （0.93）&gt;T1-T4（0.92）&gt;T2-T3（0.82）。而无音乐背景人群（NG2），准 确度是：T2-T3（0.82）≥T1-T2（0.82）&gt;T1-T4（0.74）。这些发现可以帮 助理解以希腊语为母语的人对普通话声调感知困难的根源，所以对语言教学 法的相关讨论会有所贡献。