Decoding auditory EEG responses in healthy and clinical populations: A comparative study.

BACKGROUND: Analyses of brain responses to external stimuli are typically based on the means computed across conditions. However in many cognitive and clinical applications, taking into account their variability across trials has turned out to be statistically more sensitive than comparing their means. NEW METHOD: In this study we present a novel implementation of a single-trial topographic analysis (STTA) for discriminating auditory evoked potentials at predefined time-windows. This analysis has been previously introduced for extracting spatio-temporal features at the level of the whole neural response. Adapting the STTA on specific time windows is an essential step for comparing its performance to other time-window based algorithms. RESULTS: We analyzed responses to standard vs. deviant sounds and showed that the new implementation of the STTA gives above-chance decoding results in all subjects (in comparison to 7 out of 11 with the original method). In comatose patients, the improvement of the decoding performance was even more pronounced than in healthy controls and doubled the number of significant results. COMPARISON WITH EXISTING METHOD(S): We compared the results obtained with the new STTA to those based on a logistic regression in healthy controls and patients. We showed that the first of these two comparisons provided a better performance of the logistic regression; however only the new STTA provided significant results in comatose patients at group level. CONCLUSIONS: Our results provide quantitative evidence that a systematic investigation of the accuracy of established methods in normal and clinical population is an essential step for optimizing decoding performance.

Representation of Sound Objects within Early-Stage Auditory Areas: A Repetition Effect Study Using 7T fMRI.

Environmental sounds are highly complex stimuli whose recognition depends on the interaction of top-down and bottom-up processes in the brain. Their semantic representations were shown to yield repetition suppression effects, i. e. a decrease in activity during exposure to a sound that is perceived as belonging to the same source as a preceding sound. Making use of the high spatial resolution of 7T fMRI we have investigated the representations of sound objects within early-stage auditory areas on the supratemporal plane. The primary auditory cortex was identified by means of tonotopic mapping and the non-primary areas by comparison with previous histological studies. Repeated presentations of different exemplars of the same sound source, as compared to the presentation of different sound sources, yielded significant repetition suppression effects within a subset of early-stage areas. This effect was found within the right hemisphere in primary areas A1 and R as well as two non-primary areas on the antero-medial part of the planum temporale, and within the left hemisphere in A1 and a non-primary area on the medial part of Heschl's gyrus. Thus, several, but not all early-stage auditory areas encode the meaning of environmental sounds.

Neural detection of complex sound sequences in the absence of consciousness.

The neural response to a violation of sequences of identical sounds is a typical example of the brain's sensitivity to auditory regularities. Previous literature interprets this effect as a pre-attentive and unconscious processing of sensory stimuli. By contrast, a violation to auditory global regularities, i.e. based on repeating groups of sounds, is typically detectable when subjects can consciously perceive them. Here, we challenge the notion that global detection implies consciousness by testing the neural response to global violations in a group of 24 patients with post-anoxic coma (three females, age range 45-87 years), treated with mild therapeutic hypothermia and sedation. By applying a decoding analysis to electroencephalographic responses to standard versus deviant sound sequences, we found above-chance decoding performance in 10 of 24 patients (Wilcoxon signed-rank test, P < 0.001), despite five of them being mildly hypothermic, sedated and unarousable. Furthermore, consistently with previous findings based on the mismatch negativity the progression of this decoding performance was informative of patients' chances of awakening (78% predictive of awakening). Our results show for the first time that detection of global regularities at neural level exists despite a deeply unconscious state.

Bulk silica-based luminescent materials by sol-gel processing of non-conventional precursors

The sol-gel synthesis of bulk silica-based luminescent materials using innocuous hexaethoxydisilane and hexamethoxydisilane monomers, followed by one hour thermal annealing in an inert atmosphere at 950oC-1150oC, is reported. As-synthesized hexamethoxydisilane-derived samples exhibit an intense blue photoluminescence band, whereas thermally treated ones emit stronger photoluminescence radiation peaking below 600 nm. For hexaethoxydisilane-based material, annealed at or above 1000oC, a less intense photoluminescence band, peaking between 780 nm and 850 nm that is attributed to nanocrystalline silicon is observed. Mixtures of both precursors lead to composed spectra, thus envisaging the possibility of obtaining pre-designed spectral behaviors by varying the mixture composition.

Preferred Spatial Frequencies for Human Face Processing Are Associated with Optimal Class Discrimination in the Machine

Psychophysical studies suggest that humans preferentially use a narrow band of low spatial frequencies for face recognition. Here we asked whether artificial face recognition systems have an improved recognition performance at the same spatial frequencies as humans. To this end, we estimated recognition performance over a large database of face images by computing three discriminability measures: Fisher Linear Discriminant Analysis, Non-Parametric Discriminant Analysis, and Mutual Information. In order to address frequency dependence, discriminabilities were measured as a function of (filtered) image size. All three measures revealed a maximum at the same image sizes, where the spatial frequency content corresponds to the psychophysical found frequencies. Our results therefore support the notion that the critical band of spatial frequencies for face recognition in humans and machines follows from inherent properties of face images, and that the use of these frequencies is associated with optimal face recognition performance.

On-Line Analytical Processing of Inventory Turnover

Operatiivisen tiedon tuottaminen loppukäyttäjille analyyttistä tarkastelua silmällä pitäen aiheuttaa ongelmia useille yrityksille. Diplomityö pyrkii ratkaisemaan ko. ongelman Teleste Oyj:ssä. Työ on jaettu kolmeen pääkappaleeseen. Kappale 2 selkiyttää On-Line Analytical Processing (OLAP)- käsitteen. Kappale 3 esittelee muutamia OLAP-tuotteiden valmistajia ja heidän arkkitehtuurejaan sekä tyypillisten sovellusalueiden lisäksi huomioon otettavia asioita OLAP käyttöönoton yhteydessä. Kappale 4, tuo esille varsinaisen ratkaisun. Teknisellä arkkitehtuurilla on merkittävä asema ratkaisun rakenteen kannalta. Tässä on sovellettu Microsoft:n tietovarasto kehysrakennetta. Kappaleen 4 edetessä, tapahtumakäsittelytieto muutetaan informaatioksi ja edelleen loppukäyttäjien tiedoksi. Loppukäyttäjät varustetaan tehokkaalla ja tosiaikaisella analysointityökalulla moniulotteisessa ympäristössä. Vaikka kiertonopeus otetaan työssä sovellusesimerkiksi, työ ei pyri löytämään optimaalista tasoa Telesten varastoille. Siitä huolimatta eräitä parannusehdotuksia mainitaan.

Paper Surface Image Processing for Roughness Quality Measurement

Diplomityössä on käsitelty paperin pinnankarkeuden mittausta, joka on keskeisimpiä ongelmia paperimateriaalien tutkimuksessa. Paperiteollisuudessa käytettävät mittausmenetelmät sisältävät monia haittapuolia kuten esimerkiksi epätarkkuus ja yhteensopimattomuus sileiden papereiden mittauksissa, sekä suuret vaatimukset laboratorio-olosuhteille ja menetelmien hitaus. Työssä on tutkittu optiseen sirontaan perustuvia menetelmiä pinnankarkeuden määrittämisessä. Konenäköä ja kuvan-käsittelytekniikoita tutkittiin karkeilla paperipinnoilla. Tutkimuksessa käytetyt algoritmit on tehty Matlab® ohjelmalle. Saadut tulokset osoittavat mahdollisuuden pinnankarkeuden mittaamiseen kuvauksen avulla. Parhaimman tuloksen perinteisen ja kuvausmenetelmän välillä antoi fraktaaliulottuvuuteen perustuva menetelmä.

Level Set Methods in Image Processing

This thesis gives an overview of the use of the level set methods in the field of image science. The similar fast marching method is discussed for comparison, also the narrow band and the particle level set methods are introduced. The level set method is a numerical scheme for representing, deforming and recovering structures in an arbitrary dimensions. It approximates and tracks the moving interfaces, dynamic curves and surfaces. The level set method does not define how and why some boundary is advancing the way it is but simply represents and tracks the boundary. The principal idea of the level set method is to represent the N dimensional boundary in the N+l dimensions. This gives the generality to represent even the complex boundaries. The level set methods can be powerful tools to represent dynamic boundaries, but they can require lot of computing power. Specially the basic level set method have considerable computational burden. This burden can be alleviated with more sophisticated versions of the level set algorithm like the narrow band level set method or with the programmable hardware implementation. Also the parallel approach can be used in suitable applications. It is concluded that these methods can be used in a quite broad range of image applications, like computer vision and graphics, scientific visualization and also to solve problems in computational physics. Level set methods and methods derived and inspired by it will be in the front line of image processing also in the future.

APP processing and b-amyloid deposition in sporadic Creutzfeldt-Jakob patients is dependent on Dab1.

Alzheimer"s disease and prion pathologies (e.g., Creutzfeldt-Jakob disease (CJD)) display profound neural lesions associated with aberrant protein processing and extracellular amyloid deposits. Dab1 has been implicated in the regulation of Amyloid Precursor Protein (APP), but a direct link between human prion diseases and Dab1/APP interactions has not been published. Here we examined this putative relationship in seventeen cases of sporadic CJD (sCJD) post mortem. Biochemical analyses of brain tissue revealed two groups, which also correlated with PrPsc types 1 and 2. One group, with PrPsc type 1 showed increased Dab1 phosphorylation, and lower CTF production with an absence of A deposition. The second sCJD group, which carried PrPsc type 2, showed lower levels of Dab1 phosphorylation and CTF production, and A deposition. Thus, the present observations suggest a correlation between Dab1-phosphorylation, A deposition and PrPsc type in sCJD.

Potential of antioxidant extracts produced by aqueous processing ofrenewable resources for the formulation of cosmetics

The performance of natural extracts obtained from underutilized and residual vegetal and macroalgal biomass processed with food-grade green solvents was compared with that of commercial antioxidants. Selected extracts were obtained from two terrestrial sources: winery byproducts concentrate (WBC) and chestnut burs hydrothermally fractionated extract (CBAE), and from two underutilized seaweeds: Sargassum muticum extracts, either extracted with ethanol (SmEE) or after alginate extraction and hydrothermal fractionation (SmAE) and from Ulva lactuca processed by mild acid extraction and membrane concentration (UlAE). These extracts showed in vitro antioxidant properties comparable to commercial antioxidants and were safe for topical use based on the absence of skin-irritant effects at 0.1% on reconstructed human tissues. The stability of several cosmetic model emulsions was assessed during accelerated oxidation assays. The incorporation of natural extracts produced from renewable underutilized resources at 0.4-0.5% in an oil-in-water emulsions reduced lipid oxidation during storage.

Investigation of interface between Multimedia IP Network and Call Processing Server in 3G IP Telephony Core Network

The thesis presents an overview of third generation of IP telephony. The architecture of 3G IP Telephony and its components are described. The main goal of the thesis is to investigate the interface between the Call Processing Server and Multimedia IP Networks. The interface functionality, proposed protocol stack and a general description are presented in the thesis. To provide useful services, 3G IP Telephony requires a set of control protocols for connection establishment, capabilities exchange and conference control. The Session Initiation Protocol (SIP) and the H.323 are two protocols that meet these needs. In the thesis these two protocols are investigated and compared in terms of Complexity, Extensibility, Scalability, Services, Resource Utilization and Management.

How environmental sounds become meaningful

The term "sound object" describes an auditory experience that is associated with an acoustic event produced by a sound source. In natural settings, a sound produced by a living being or an object provides information about the identity and the location of the sound source. Sound's identity is orocessed alono the ventral "What" pathway which consists of regions within the superior and middle temporal cortices as well as the inferior frontal gyrus. This work concerns the creation of individual auditory object representations in narrow semantic categories and their plasticity using electrical imaging. Discrimination of sounds from broad category has been shown to occur along a temporal hierarchy and in different brain regions along the ventral "What" pathway. However, sounds belonging to the same semantic category, such as faces or voices, were shown to be discriminated in specific brain areas and are thought to represent a special class of stimuli. I have investigated how cortical representations of a narrow category, here birdsongs, is modulated by training novices to recognized songs of individual bird species. Dynamic analysis of distributed source estimations revealed differential sound object representations within the auditory ventral "What" pathway as a function of the level of expertise newly acquired. Correct recognition of trained items induces a sharpening within a left-lateralized semantic network starting around 200ms, whereas untrained items' processing occurs later in lower-level and memory-related regions. With another category of sounds belonging to the same category, here heartbeats, I investigated the cortical representations of correct and incorrect recognition of sounds. Source estimations revealed differential representations partially overlapping with regions involved in the semantic network that is activated when participants became experts in the task. Incorrect recognition also induces a higher activation when compared to correct recognition in regions processing lower-level features. The discrimination of heartbeat sounds is a difficult task and requires a continuous listening. I investigated whether the repetition effects are modulated by participants' behavioral performance. Dynamic source estimations revealed repetition suppression in areas located outside of the semantic network. Therefore, individual environmental sounds become meaningful with training. Their representations mainly involve a left-lateralized network of brain regions that are tuned with expertise, as well as other brain areas, not related to semantic processing, and occurring in early stages of semantic processing. -- Le terme objet sonore" décrit une expérience auditive associée à un événement acoustique produit par une source sonore. Dans l'environnement, un son produit par un être vivant ou un objet fournit des informations concernant l'identité et la localisation de la source sonore. Les informations concernant l'identité d'un son sont traitée le long de la voie ventrale di "Quoi". Cette voie est composée de regions situées dans le cortex temporal et frontal. L'objet de ce travail est d'étudier quels sont les neuro-mecanismes impliqués dans la représentation de nouveaux objets sonores appartenant à une meme catégorie sémantique ainsi que les phénomènes de plasticité à l'aide de l'imagerie électrique. Il a été montré que la discrimination de sons appartenant à différentes catégories sémantiques survient dans différentes aires situées le long la voie «Quoi» et suit une hiérarchie temporelle II a également été montré que la discrimination de sons appartenant à la même catégorie sémantique tels que les visages ou les voix, survient dans des aires spécifiques et représenteraient des stimuli particuliers. J'ai étudié comment les représentations corticales de sons appartenant à une même catégorie sémantique, dans ce cas des chants d'oiseaux, sont modifiées suite à un entraînement Pour ce faire, des sujets novices ont été entraînés à reconnaître des chants d'oiseaux spécifiques L'analyse des estimations des sources neuronales au cours du temps a montré que les representations des objets sonores activent de manière différente des régions situées le long de la vo,e ventrale en fonction du niveau d'expertise acquis grâce à l'entraînement. La reconnaissance des chants pour lesquels les sujets ont été entraînés implique un réseau sémantique principalement situé dans l'hémisphère gauche activé autour de 200ms. Au contraire, la reconnaissance des chants pour lesquels les sujets n'ont pas été entraînés survient plus tardivement dans des régions de plus bas niveau. J'ai ensuite étudié les mécanismes impliqués dans la reconnaissance et non reconnaissance de sons appartenant à une autre catégorie, .es battements de coeur. L'analyse des sources neuronales a montre que certaines régions du réseau sémantique lié à l'expertise acquise sont recrutées de maniere différente en fonction de la reconnaissance ou non reconnaissance du son La non reconnaissance des sons recrute des régions de plus bas niveau. La discrimination des bruits cardiaques est une tâche difficile et nécessite une écoute continue du son. J'ai étudié l'influence des réponses comportementales sur les effets de répétitions. L'analyse des sources neuronales a montré que la reconnaissance ou non reconnaissance des sons induisent des effets de repétition différents dans des régions situées en dehors des aires du réseau sémantique. Ainsi, les sons acquièrent un sens grâce à l'entraînement. Leur représentation corticale implique principalement un réseau d'aires cérébrales situé dans l'hémisphère gauche, dont l'activité est optimisée avec l'acquisition d'un certain niveau d'expertise, ainsi que d'autres régions qui ne sont pas liée au traitement de l'information sémantique. L'activité de ce réseau sémantique survient plus rapidemement que la prédiction par le modèle de la hiérarchie temporelle.

Potential Acquisition Candidates for a Supplier of Wood Processing Machinery

Diplomityön tavoitteena oli sopivimman yritysostokohteen valitseminen useiden kilpailijoiden joukosta puunkäsittelykoneiden toimittajalle. Ensin esiteltiin Suomen metsäteollisuus sekä sen osaamistarpeista noussut metsäklusteri pääosin kohdeyrityksen näkökulmasta. Seuraavaksi annettiin kuva yrityksen tuotteista, kilpailijoista ja asiakkaista. Yritysostoprosessi kuvattiin sekä esille tuotiin yleiset motiivit ja kriittiset menestystekijät. Lisäksi kuvattiin kilpailijoiden ja liiketoimintaympäristön analysointi yrityksen menestyksen edellytyksenä. Puuntyöstökoneiden markkinat segmentoitiin ja analysoitiin vuodesta 1990 aina tähän päivään asti, jotta löydettäisiin kehityskelpoiset osa-alueet eli alueet, joissa yrityksen markkinaosuutta voitaisiin kasvattaa. Kandidaattien ominaisuuksia verrattiin yritysoston motiiveihin. Yritysten tuotteet sekä maantieteellinen sijainti pisteytettiin, jotta sopivimmat yritykset nousisivat esille. Kolme yritystä valittiin syvällisempään tarkasteluun. Yritysten tuotteita, taloudellista asemaa ja globaalia verkostoa vertailtiin keskenään muiden tekijöiden, kuten maailmantalouden ohessa. Taloudellisesti vakaa ja teknisesti monipuolinen yritys kohtasi yritysoston motiivit parhaiten. Kohteen positiivisia puolia olivat sijainti, tuotteet ja palvelut. Lisäksi, yritys sopii ostajan strategiaan sekä auttaa kohtaamaan asiakkaiden nykyiset ja tulevat tarpeet.