Cognitive Auditory Evoked Potentials in Investigation of Hearing Discrimination

Preattentive perception of occasional deviating stimuli in the stream of standard stimuli can be recorded with cognitive event-related potential (ERP) mismatch negativity (MMN). The earlier detection of stimuli at the auditory cortex can be examined with N1 and P2 ERPs. The MMN recording does not require co-operation, it correlates with perceptual threshold, and even complex sounds can be used as stimuli. The aim of this study was to examine different aspects that should be considered when measuring discrimination of hearing with ERPs. The MMN was found to be stimulusintensity- dependent. As the intensity of sine wave stimuli was increased from 40 to 80 dB HL, MMN mean amplitudes increased. The effect of stimulus frequency on the MMN was studied so that the pitch difference would be equal in each stimulus block according to the psychophysiological mel scale or the difference limen of frequency (DLF). However, the blocks differed from each other. The contralateral white noise masking (50 dB EML) was found to attenuate the MMN amplitude when the right ear was stimulated. The N1 amplitude was attenuated and, in contrast, P2 amplitude was not affected by contralateral white noise masking. The perception and production of vowels by four postlingually deafened patients with a cochlear implant were studied. The MMN response could be elicited in the patient with the best vowel perception abilities. The results of the studies show that concerning the MMN recordings, the stimulus parameters and recording procedure design have a great influence on the results.

Central auditory processing and the acquisition of phonology in 2-year-old children with recurrent acute otitis media

Middle ear infections (acute otitis media, AOM) are among the most common infectious diseases in childhood, their incidence being greatest at the age of 6–12 months. Approximately 10–30% of children undergo repetitive periods of AOM, referred to as recurrent acute otitis media (RAOM). Middle ear fluid during an AOM episode causes, on average, 20–30 dB of hearing loss lasting from a few days to as much as a couple of months. It is well known that even a mild permanent hearing loss has an effect on language development but so far there is no consensus regarding the consequences of RAOM on childhood language acquisition. The results of studies on middle ear infections and language development have been partly discrepant and the exact effects of RAOM on the developing central auditory nervous system are as yet unknown. This thesis aims to examine central auditory processing and speech production among 2-year-old children with RAOM. Event-related potentials (ERPs) extracted from electroencephalography can be used to objectively investigate the functioning of the central auditory nervous system. For the first time this thesis has utilized auditory ERPs to study sound encoding and preattentive auditory discrimination of speech stimuli, and neural mechanisms of involuntary auditory attention in children with RAOM. Furthermore, the level of phonological development was studied by investigating the number and the quality of consonants produced by these children. Acquisition of consonant phonemes, which are harder to hear than vowels, is a good indicator of the ability to form accurate memory representations of ambient language and has not been studied previously in Finnish-speaking children with RAOM. The results showed that the cortical sound encoding was intact but the preattentive auditory discrimination of multiple speech sound features was atypical in those children with RAOM. Furthermore, their neural mechanisms of auditory attention differed from those of their peers, thus indicating that children with RAOM are atypically sensitive to novel but meaningless sounds. The children with RAOM also produced fewer consonants than their controls. Noticeably, they had a delay in the acquisition of word-medial consonants and the Finnish phoneme /s/, which is acoustically challenging to perceive compared to the other Finnish phonemes. The findings indicate the immaturity of central auditory processing in the children with RAOM, and this might also emerge in speech production. This thesis also showed that the effects of RAOM on central auditory processing are long-lasting because the children had healthy ears at the time of the study. An effective neural network for speech sound processing is a basic requisite of language acquisition, and RAOM in early childhood should be considered as a risk factor for language development.

Synchronous Digital Hierarchy implementation to a Radio Transmission Node

Kiristyville markkinoille on aina tuotava jotain uutta tarjottavaa ja SDH-kortti on yksi sellainen tuote jonka Nokia Networks julkistaa osaksi uutta Nokia Flexihub Nodea. Tavoitteena on suunnitella VC-12kanavoitu STM-1 kortti yhdistämään ylemmän tason tietoliikenneverkko suuren kapasiteetin radioon. Ennen kuin markkinoilla on valmis tuote, on sen takana valtaisa määrä työtä. Erilaisia dokumentteja on pitänyt tuottaa ja sopimuksia tehdä. Esimerkiksi vaatimusmäärittelyt on oltava selvät, jotta tiedetään mitä tuotteelta halutaan. Tätä ennen on kuitenkin pitänyt ymmärtää miten SDHtoimii ja miten otsikkotavuja käsitellään. Myös erilaiset piirivalinnat aiheuttavat miettimistä, sillä markkinoilla on runsaasti valmiita piirejä SDH signaalinkäsittelyyn. Varma tiedonsiirto on tärkeää puhelinoperaattorille ja siksi joudutaan miettimään varmennuksia ja niiden toteuttamista. Myös synkronointi on tärkeä osa SDH järjestelmää ja sen toteuttaminen hyvin on tärkeää. Hälytykset on otettava huomioon ja mietittävä, miten niiden käsittely saadaan hoidettua järkevästi, ilman että mikään järjestelmän osa ruuhkautuu kohtuuttomasti. Tässä Diplomityössä on tutustuttu SDH-järjestelmään, otsikkotavujen käsittelyyn ja vaatimusmäärittelyihin.

Kiinteistön ohjaus- ja valvontajärjestelmän toteutus mobiiliympäristöön

Ohjelmistoprojektin läpivienti vaatii suunnittelua ja yhteisiä tapaamisia toimittajan ja asiakkaan kesken. Ohjelmistotuotannon prosessit ovat määrittely, suunnittelu, toteutus, testaus ja käyttöönotto. Tärkeimmät dokumentit ovat projektisuunnitelma, toiminnallinen määrittely ja tekninen määrittely. Ongelmia projektin läpiviennissä voi tulla silloin, jos toimittaja ja asiakas eivät ymmärrä toisiaan. Tässä työssä tehdään SMSviestejä käsittelevä mobiilisovellus ja siihen liittyvät projektisuunnitelma sekä määrittelydokumentit. Mobiilisovellus ohjelmoidaan J2ME:llä, joka on sulautettujen järjestelmien ohjelmointiin suunniteltu Java-kieli. Sovellus tukee toisen asteen opiskelijoille suunnattuja mobiiliohjelmointi opintoja. Opintojakso kuuluu Pohjois- Karjalan ammattiopiston järjestämään turvallisuusalan koulutukseen. Sovelluksella voidaan lähettää ohjausviestejä OUMAN EH-60 -ohjaus- ja valvontayksikköön. Yksikön avulla voi ohjata ja valvoa esimerkiksi kiinteistön lämmönsäätöä, vesivahinkoja, oven lukitusta jne. Tässä työssä tehtävällä sovelluksella demonstroidaan kesämökin ohjausta. Langaton tiedonsiirto tulee tulevaisuudessa lisääntymään kiinteistöjen ohjaus- ja valvontajärjestelmänä. Hätä- ja valvontaviestit lähetetään automaattisesti kiinteistön omistajalle, hoivapalveluyrittäjälle, talohuoltoon tai hätäkeskukseen. Kiinteistön omistaja voi omalla matkapuhelimellaan ajasta ja paikasta riippumattavalvoa ja ohjata kiinteistöään reaaliaikaisesti. Pohjois-Karjalan ammattiopisto haluaa olla kehittämässä ja toteuttamassa turvallisuusalan koulutusta nyt ja tulevaisuudessa.

Sekoitusprosessin laadunvalvonnan suunnittelu

Nokian Renkaat Oyj:ssä on suuntaus päivittäin valmistettavien kumisekoitusten määrien lisäämiseen. Sekoitusmäärien kasvaessa myös laadunvalvontamittauksien kapasiteettia pitää nostaa tai vaihtoehtoisesti vähentää näytteiden tutkimiseen kuluvaa aikaa tai tutkittavien näytteiden määrää. On mietitty, voitaisiinko näytteenottopaikkaa vaihtamalla saada edustavampi näyte. Aikaistamalla näytteenottopaikkaa näytteet saataisiin tutkittua aikaisemmin ja siten sekoitukset saataisiin käyttöön entistä nopeammin. Teoriaosassa käsitellään kumisekoitusprosessia ja tutustutaan käytettävään prosessilaitteistoon ja prosessin eri vaiheisiin. Lisäksi tutustutaan prosessin ohjaukseen, prosessimittauksiin, prosessin säätöihin ja hälytyksiin. Työssä käsitellään myös laatuun vaikuttavia tekijöitä ja perehdytään käytössä oleviin laadunvalvontamittauksiin ja näytteiden analysointiin. Kokeellisessa osassa tutkitaan, mikä olisi paras näytteenottokohta, mietitään mittausten ja mittausajan vähentämisen vaikutuksia sekä sitä, miten näytteet tulisi merkitä. Lisäksi kokeellisessa osassa tehdään neuroverkkomalli viskositeetin ennustamiseksi.

Voimalaitoksen toiminnallinen suunnittelu

Diplomityön tavoitteena oli antaa kuva vastapainevoimalaitoksen automaation toiminnallisesta suunnittelusta ja soveltaa teoriaa suunnittelemalla toiminnallisuus vesihöyrypiirin tärkeimmille osuuksille. Työssä on esitelty tyypillinen EPCM-voimalaitosprojekti, joka toteutetaan ulkopuolisen avustajan kanssa tehdyllä yhteistyöllä. Projektin koostuu laitoksen suunnittelu-, rakennus-, asennus- sekä käyttöönottovaiheista. Huomioitavia asioita ovat mm. projektin budjetti sekä aikataulu. Valvonnalla on suuri merkitys projektin onnistumiseen. Lisäksi työssä esitellään vastapainevoimalaitoksen vesihöyrypiirin prosessi, pääsäädöt sekä automaatiojärjestelmä. Vesihöyrypiirillä tarkoitetaan syöttövesi-, höyry- ja kaukolämpöjärjestelmää. Pääsäädöillä pyritään saamaan tuotanto vastaamaan kulutusta. Voimalaitoksen painopiste on kaukolämmön tuottaminen. Automaatiojärjestelmän toiminnoilla tarkoitetaan järjestelmän suorittamia ohjauksia, säätöjä sekä hälytyksiä. Toiminnallisessa suunnittelussa tehdään toimilaitteille niin yksittäisohjaukset, säädöt kuin hälytysluettelot. Työssä tehty toiminnallinen suunnittelu keskittyy erityisesti toimilaitteiden säätöpiireihin. Säätöpiirit koostuvat tärkeimmistä prosessiin liittyvistä komponenteista ja säätömerkeistä. Toiminnallisen suunnittelun dokumentaatioita käytetään automaatiojärjestelmän sovellusohjelmoinnin pohjana.

Antenatal inflammation and brain pathology in preterm infants

Chorioamnionitis is known to be an important risk factor underlying preterm delivery, and it has also been suggested to associate with brain lesions and deviant neurological development in both preterm and term infants. Cytokines are believed to be the link causing the deleterious effects of inflammation to the nervous system. Their genetic regulation has also been suggested to play a role, as interleukin (IL)-6 -174 and -572 genotypes, which partly regulate IL-6 synthesis responses, have been connected with deviant neurological development in preterm infants. We evaluated the association of histological chorioamnionitis with brain lesions, regional brain volumes, and the functioning of the auditory pathway in very low birth weight/very low gestational age (VLBW/VLGA) infants. In addition, we investigated the association between IL-6 -174 and -572 genotypes and histological chorioamnionitis, neonatal infections, and brain lesions and regional brain volumes in VLBW/VLGA infants. This study is a part of a larger multidisciplinary project PIPARI (Development and Functioning of Very Low Birth Weight Infants from Infancy to School Age), in which the survivors of a 6-year cohort of VLBW/VLGA infants (n=274) are being followed until school age in Turku University Central Hospital, Finland. Placental samples were collected in the delivery room, and were analyzed for histological inflammatory findings. Blood samples from the infants were collected and DNA was genotyped for IL-6-174 and -572 polymorphisms (GG/GC/CC). Brain ultrasound examinations were performed repeatedly in the neonatal intensive care unit and at term age, and were analysed for structural brain lesions. Brain magnetic resonance imaging was performed at term age, and was analysed for regional brain volumes. In addition, diffusion tensor imaging was performed at term, and was used to analyse fractional anisotrophy and the apparent diffusion coefficient of inferior colliculus. The brainstem auditory evoked potential recordings were carried out according to the routine clinical procedure at median age of 30 days after term age. In our study, we found that histological chorioamnionitis was not an independent risk factor for brain lesions, reduced regional brain volumes or abnormal functioning of the auditory pathway in VLBW/VLGA infants. In addition, we found that IL-6 -174 GG and -572 GC genotypes were associated with a higher incidence of histological chorioamnionitis, and that -174 CC genotype associated with higher incidence of septicaemia. The analysed IL-6 genotypes were not associated with other brain lesions, but a reduced volume of basal ganglia and thalami was associated with IL-6 -174 CC and -572 GG genotypes. In conclusion, our findings suggest that histological chorioamnionitis is not an independent risk factor for the brain development of VLBW/VLGA infants, or that the risk caused by inflammation does not exceed the risks attributed to other underlying pathologies behind preterm deliveries. In addition, our findings give reason to propose that IL-6 promoter genotypes have a role in the defence against serious infections and in the brain development of VLBW/VLGA infants.

MS-potilaiden kognitiiviset häiriöt ja PASAT-testissä suoriutuminen

Eija Rosti-Otajärven väitöskirja Cognitive deficits and the Paced Auditory Serial Addition Test performance among patients with multiple sclerosis (Helsingin yliopisto 2009).

"Dov'è la sinistra?" Hemispatial neglect in stroke

As long as the incidence of stroke continues to grow, patients with large right hemisphere lesions suffering from hemispatial neglect will require neuropsychological evaluation and rehabilitation. The inability to process information especially that coming from the left side accompanied by the magnetic orientation to the ipsilesional side represents a real challenge for rehabilitation. This dissertation is concerned with crucial aspects in the clinical neuropsychological practice of hemispatial neglect. In studying the convergence of the visual and behavioural test batteries in the assessment of neglect, nine of the seventeen patients, who completed both the conventional subtests of the Behavioural Inattention Test and the Catherine Bergego Scale assessments, showed a similar severity of neglect and thus good convergence in both tests. However, patients with neglect and hemianopia had poorer scores in the line bisection test and they displayed stronger neglect in behaviour than patients with pure neglect. The second study examined, whether arm activation, modified from the Constraint Induced Movement Therapy, could be applied as neglect rehabilitation alone without any visual training. Twelve acute- or subacute patients were randomized into two rehabilitation groups: arm activation training or traditional voluntary visual scanning training. Neglect was ameliorated significantly or almost significantly in both training groups due to rehabilitation with the effect being maintained for at least six months. In studying the reflections of hemispatial neglect on visual memory, the associations of severity of neglect and visual memory performances were explored. The performances of acute and subacute patients with hemispatial neglect were compared with the performances of matched healthy control subjects. As hypothesized, encoding from the left side and immediate recall of visual material were significantly compromised in patients with neglect. Another mechanism of neglect affecting visual memory processes is observed in delayed visual reproduction. Delayed recall demands that the individual must make a match helped by a cue or it requires a search for relevant material from long-term memory storage. In the case of representational neglect, the search may succeed but the left side of the recollected memory still fails to open. Visual and auditory evoked potentials were measured in 21 patients with hemispatial neglect. Stimuli coming from the left or right were processed differently in both sensory modalities in acute and subacute patients as compared with the chronic patients. The differences equalized during the course of recovery. Recovery from hemispatial neglect was strongly associated with early rehabilitation and with the severity of neglect. Extinction was common in patients with neglect and it did not ameliorate with the recovery of neglect. The presence of pusher symptom hampered amelioration of visual neglect in acute and subacute stroke patients, whereas depression did not have any significant effect in the early phases after the stroke. However, depression had an unfavourable effect on recovery in the chronic phase. In conclusion, the combination of neglect and hemianopia may explain part of the residual behavioural neglect that is no longer evident in visual testing. Further research is needed in order to determine which specific rehabilitation procedures would be most beneficial in patients suffering the combination of neglect and hemianopia. Arm activation should be included in the rehabilitation programs of neglect; this is a useful technique for patients who need bedside treatment in the acute phase. With respect to the deficit in visual memory in association with neglect, the possible mechanisms of lateralized deficit in delayed recall need to be further examined and clarified. Intensive treatment induced recovery in both severe and moderate visual neglect long after the first two to first three months after the stroke.

“IT’S ALL RIGHT”. Multimodal rightward spatial bias modified by age and praxis

The general goal of the present work was to study whether spatial perceptual asymmetry initially observed in linguistic dichotic listening studies is related to the linguistic nature of the stimuli and/or is modality-specific, as well as to investigate whether the spatial perceptual/attentional asymmetry changes as a function of age and sensory deficit via praxis. Several dichotic listening studies with linguistic stimuli have shown that the inherent perceptual right ear advantage (REA), which presumably results from the left lateralized linguistic functions (bottom-up processes), can be modified with executive functions (top-down control). Executive functions mature slowly during childhood, are well developed in adulthood, and decline as a function of ageing. In Study I, the purpose was to investigate with a cross-sectional experiment from a lifespan perspective the age-related changes in top-down control of REA for linguistic stimuli in dichotic listening with a forced-attention paradigm (DL). In Study II, the aim was to determine whether the REA is linguistic-stimulus-specific or not, and whether the lifespan changes in perceptual asymmetry observed in dichotic listening would exist also in auditory spatial attention tasks that put load on attentional control. In Study III, using visual spatial attention tasks, mimicking the auditory tasks applied in Study II, it was investigated whether or not the stimulus-non-specific rightward spatial bias found in auditory modality is a multimodal phenomenon. Finally, as it has been suggested that the absence of visual input in blind participants leads to improved auditory spatial perceptual and cognitive skills, the aim in Study IV was to determine, whether blindness modifies the ear advantage in DL. Altogether 180-190 right-handed participants between 5 and 79 years of age were studied in Studies I to III, and in Study IV the performance of 14 blind individuals was compared with that of 129 normally sighted individuals. The results showed that only rightward spatial bias was observed in tasks with intensive attentional load, independent of the type of stimuli (linguistic vs. non-linguistic) or the modality (auditory vs. visual). This multimodal rightward spatial bias probably results from a complex interaction of asymmetrical perceptual, attentional, and/or motor mechanisms. Most importantly, the strength of the rightward spatial bias changed as a function of age and augmented praxis due to sensory deficit. The efficiency of the performance in spatial attention tasks and the ability to overcome the rightward spatial bias increased during childhood, was at its best in young adulthood, and decreased as a function of ageing. Between the ages of 5 and 11 years probably at first develops movement and impulse control, followed by the gradual development of abilities to inhibit distractions and disengage attention. The errors especially in bilateral stimulus conditions suggest that a mild phenomenon resembling extinction can be observed throughout the lifespan, but especially the ability to distribute attention to multiple targets simultaneously decreases in the course of ageing. Blindness enhances the processing of auditory bilateral linguistic stimuli, the ability to overcome a stimulus-driven laterality effect related to speech sound perception, and the ability to direct attention to an appropriate spatial location. It was concluded that the ability to voluntarily suppress and inhibit the multimodal rightward spatial bias changes as a function of age and praxis due to sensory deficit and probably reflects the developmental level of executive functions.

Skill Development in Music Reading. The Eye-Movement Approach

This dissertation examined skill development in music reading by focusing on the visual processing of music notation in different music-reading tasks. Each of the three experiments of this dissertation addressed one of the three types of music reading: (i) sight-reading, i.e. reading and performing completely unknown music, (ii) rehearsed reading, during which the performer is already familiar with the music being played, and (iii) silent reading with no performance requirements. The use of the eye-tracking methodology allowed the recording of the readers’ eye movements from the time of music reading with extreme precision. Due to the lack of coherence in the smallish amount of prior studies on eye movements in music reading, the dissertation also had a heavy methodological emphasis. The present dissertation thus aimed to promote two major issues: (1) it investigated the eye-movement indicators of skill and skill development in sight-reading, rehearsed reading and silent reading, and (2) developed and tested suitable methods that can be used by future studies on the topic. Experiment I focused on the eye-movement behaviour of adults during their first steps of learning to read music notation. The longitudinal experiment spanned a nine-month long music-training period, during which 49 participants (university students taking part in a compulsory music course) sight-read and performed a series of simple melodies in three measurement sessions. Participants with no musical background were entitled as “novices”, whereas “amateurs” had had musical training prior to the experiment. The main issue of interest was the changes in the novices’ eye movements and performances across the measurements while the amateurs offered a point of reference for the assessment of the novices’ development. The experiment showed that the novices tended to sight-read in a more stepwise fashion than the amateurs, the latter group manifesting more back-and-forth eye movements. The novices’ skill development was reflected by the faster identification of note symbols involved in larger melodic intervals. Across the measurements, the novices also began to show sensitivity to the melodies’ metrical structure, which the amateurs demonstrated from the very beginning. The stimulus melodies consisted of quarter notes, making the effects of meter and larger melodic intervals distinguishable from effects caused by, say, different rhythmic patterns. Experiment II explored the eye movements of 40 experienced musicians (music education students and music performance students) during temporally controlled rehearsed reading. This cross-sectional experiment focused on the eye-movement effects of one-bar-long melodic alterations placed within a familiar melody. The synchronizing of the performance and eye-movement recordings enabled the investigation of the eye-hand span, i.e., the temporal gap between a performed note and the point of gaze. The eye-hand span was typically found to remain around one second. Music performance students demonstrated increased professing efficiency by their shorter average fixation durations as well as in the two examined eye-hand span measures: these participants used larger eye-hand spans more frequently and inspected more of the musical score during the performance of one metrical beat than students of music education. Although all participants produced performances almost indistinguishable in terms of their auditory characteristics, the altered bars indeed affected the reading of the score: the general effects of expertise in terms of the two eye- hand span measures, demonstrated by the music performance students, disappeared in the face of the melodic alterations. Experiment III was a longitudinal experiment designed to examine the differences between adult novice and amateur musicians’ silent reading of music notation, as well as the changes the 49 participants manifested during a nine-month long music course. From a methodological perspective, an opening to research on eye movements in music reading was the inclusion of a verbal protocol in the research design: after viewing the musical image, the readers were asked to describe what they had seen. A two-way categorization for verbal descriptions was developed in order to assess the quality of extracted musical information. More extensive musical background was related to shorter average fixation duration, more linear scanning of the musical image, and more sophisticated verbal descriptions of the music in question. No apparent effects of skill development were observed for the novice music readers alone, but all participants improved their verbal descriptions towards the last measurement. Apart from the background-related differences between groups of participants, combining verbal and eye-movement data in a cluster analysis identified three styles of silent reading. The finding demonstrated individual differences in how the freely defined silent-reading task was approached. This dissertation is among the first presentations of a series of experiments systematically addressing the visual processing of music notation in various types of music-reading tasks and focusing especially on the eye-movement indicators of developing music-reading skill. Overall, the experiments demonstrate that the music-reading processes are affected not only by “top-down” factors, such as musical background, but also by the “bottom-up” effects of specific features of music notation, such as pitch heights, metrical division, rhythmic patterns and unexpected melodic events. From a methodological perspective, the experiments emphasize the importance of systematic stimulus design, temporal control during performance tasks, and the development of complementary methods, for easing the interpretation of the eye-movement data. To conclude, this dissertation suggests that advances in comprehending the cognitive aspects of music reading, the nature of expertise in this musical task, and the development of educational tools can be attained through the systematic application of the eye-tracking methodology also in this specific domain.

Tilintarkastajan kurinpidollinen vastuu

Tutkielman tavoitteena oli tutkia, millaista on tilintarkastajan kurinpidollinen vastuu ja kuinka tällainen vastuu voi realisoitua käytännössä. Alkuosa käsittelee tilintarkastusjärjestelmää teoreettiselta kannalta, vastaavasti jälkimmäisessä osassa on tutkittu tilintarkastajille langetettuja sanktioita ja niiden määriä. Näiden perusteella on pyritty tekemään johtopäätöksiä rangaistuskäytännöistä ja niiden mahdollisista muutoksista. Tutkimuksen tulokset osoittavat, että tilintarkastusjärjestelmä on juuri nyt voimakkaan muutoksen alaisena. Vuoden 2007 lakiuudistuksen jälkeen kansainvälistyminen ja EU:n tasoiset säännökset tullevat muokkaamaan tilintarkastusjärjestelmää entisestään. Kaiken kaikkiaan säännökset ovat tilintarkastajilla kuitenkin melko hyvin hallinnassa, sillä keskimäärin 5-10 tapauksessa vuosittain tutkitaan tilintarkastajan toimintaa, mutta vain muutama johtaa kurinpidollisiin toimenpiteisiin.

Novel word learning ability in chronic post-stroke aphasia : variability and modality effects

Novel word learning has been rarely studied in people with aphasia (PWA), although it can provide a relatively pure measure of their learning potential, and thereby contribute to the development of effective aphasia treatment methods. The main aim of the present thesis was to explore the capacity of PWA for associative learning of word–referent pairings and cognitive-linguistic factors related to it. More specifically, the thesis examined learning and long-term maintenance of the learned pairings, the role of lexical-semantic abilities in learning as well as acquisition of phonological versus semantic information in associative novel word learning. Furthermore, the effect of modality on associative novel word learning and the neural underpinnings of successful learning were explored. The learning experiments utilized the Ancient Farming Equipment (AFE) paradigm that employs drawings of unfamiliar referents and their unfamiliar names. Case studies of Finnishand English-speaking people with chronic aphasia (n = 6) were conducted in the investigation. The learning results of PWA were compared to those of healthy control participants, and active production of the novel words and their semantic definitions was used as learning outcome measures. PWA learned novel word–novel referent pairings, but the variation between individuals was very wide, from more modest outcomes (Studies I–II) up to levels on a par with healthy individuals (Studies III–IV). In incidental learning of semantic definitions, none of the PWA reached the performance level of the healthy control participants. Some PWA maintained part of the learning outcomes up to months post-training, and one individual showed full maintenance of the novel words at six months post-training (Study IV). Intact lexical-semantic processing skills promoted learning in PWA (Studies I–II) but poor phonological short-term memory capacities did not rule out novel word learning. In two PWA with successful learning and long-term maintenance of novel word–novel referent pairings, learning relied on orthographic input while auditory input led to significantly inferior learning outcomes (Studies III–IV). In one of these individuals, this previously undetected modalityspecific learning ability was successfully translated into training with familiar but inaccessible everyday words (Study IV). Functional magnetic resonance imaging revealed that this individual had a disconnected dorsal speech processing pathway in the left hemisphere, but a right-hemispheric neural network mediated successful novel word learning via reading. Finally, the results of Study III suggested that the cognitive-linguistic profile may not always predict the optimal learning channel for an individual with aphasia. Small-scale learning probes seem therefore useful in revealing functional learning channels in post-stroke aphasia.

Musiikillisen asiantuntijuuden vaikutus äänten havainto-oppimiseen

Miia Seppäsen psykologian väitöskirja Auditory perceptual learning in musicians and non-musicians - Event-related potential studies on rapid plasticity (Helsingin yliopisto 2013).

Trophic cascades in boreal landscapes: top predator protection on tree seedlings and forest grouse

Changes in the abundance of top predators have brought about notable, cascading effects in ecosystems around the world. In this thesis, I examined several potential trophic cascades in boreal ecosystems, and their separate interspecific interactions. The main aim of the thesis was to investigate whether predators in the boreal forests have direct or indirect cascading effects on the lower trophic levels. First, I compared the browsing effects of different mammalian herbivores by excluding varying combinations of voles, hares and cervids from accessing the seedlings of silver birch (Betula pendula), Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Additionally, I studied the effect of simulated predation risk on vole browsing by using auditory cues of owls. Moving upwards on the trophic levels, I examined the intraguild interactions between the golden eagle (Aquila chrysaetos), and its mesopredator prey, the red fox (Vulpes vulpes) and the pine marten (Martes martes). To look at an entire potential trophic cascade, I further studied the combined impacts of eagles and mesopredators on the black grouse (Tetrao tetrix) and the hazel grouse (Tetrastes bonasia), predicting that the shared forest grouse prey would benefit from eagle presence. From the tree species studied, birch appears to be the most palatable one for the mammalian herbivores. I observed growth reductions in the presences of cervids and low survival associated with hares and voles, which suggests that they all weaken regeneration in birch stands. Furthermore, the simulated owl predation risk appeared to reduce vole browsing on birches in late summer, although the preferred grass forage is then old and less palatable. Browsing by voles and hares had a negative effect on the condition and survival of Scots pine, but in contrast, the impact of mammalian herbivores on spruce was found to be small, at least when more preferred food is available. I observed that the presence of golden eagles had a negative effect on the abundance of adult black grouse but a positive, protective effect on the proportion of juveniles in both black grouse and hazel grouse. Yet, this positive effect was not dependent on the abundance foxes or martens, nor did eagles seem to effectively decrease the abundance of these mesopredators. Conversely, the protection effect on grouse could arise from fear effects and also be mediated by other mesopredators. The results of this thesis provide important new information about trophic interactions in the boreal food webs. They highlight how different groups of mammalian herbivores vary in their effects on the growth and condition of different tree seedlings. Lowered cervid abundances could improve birch regeneration, which indirectly supports the idea that the key predators of cervids could cause cascading effects also in Fennoscandian forests. Owls seem to reduce vole browsing through an intimidation effect, which is a novel result of the cascading effects of owl vocalisation and could even have applications for protecting birch seedlings. In the third cascade examined in this thesis, I found the golden eagle to have a protective effect on the reproducing forest grouse, but it remains unclear through which smaller predators this effect is mediated. Overall, the results of this thesis further support the idea that there are cascading effects in the forests of Northern Europe, and that they are triggered by both direct and non‐lethal effects of predation.