Clinical applications of real-time FMRI neurofeedback training – premises, promises, and pitfalls

Neurofeedback training represents a form of biofeedback training with a history of over 50 years. During neurofeedback training participants aim to gain control over a feedback signal that represents the activity of a brain region or network of interest. As such, it holds promise for clinical translation as an add-on treatment for psychiatric and neurological conditions. Yet, currently available evidence for its therapeutic efficacy remains limited. Originally provided based on cortical signals measured with electroencephalography (EEG), methodological developments have allowed providing neurofeedback based on (cortical and subcortical) brain signals acquired from functional magnetic resonance imaging (fMRI). The aim of this thesis was to test the feasibility and clinical efficacy of fMRI neurofeedback (fMRI-NF) training in a psychiatric population and to develop protocols that allow translating the technique to motor rehabilitation. Specifically, this thesis summarises the clinical and neuroimaging results from a randomised controlled trial conducted in patients suffering from depression. Depression represents a leading cause of disability in adults and epidemiological data indicates that up to one third of patients remain depressed after treatment. Another focus was the development of a motor imagery-based fMRI-NF protocol in healthy participants. This work has informed a proof-of-concept study for motor rehabilitation in stroke survivors, for which the methodology was preregistered on a public platform before data collection started to increase transparency. The thesis aims to address problematic research practices that have been attributed to the replication crisis in many areas of science, including a clear separation of planned and exploratory hypotheses and the use and adaptation of alternative statistical methods. A review chapter discusses potential electrophysiological target signatures for EEG-NF to improve motor symptoms in Parkinson’s disease patients. The thesis concludes with a discussion of current premises, promises, and pitfalls in clinical applications of neurofeedback training and considerations for clinical trials development

May the power be with you: are there highly powered studies in neuroscience, and how can we get more of them?

Statistical power is essential for robust science and replicability, but a meta-analysis by Button et al. in 2013 diagnosed a "power failure" for neuroscience. In contrast, Nord et al. (J Neurosci 37: 8051-8061, 2017) re-analyzed these data and suggested that some studies feature high power. We illustrate how publication and researcher bias might have inflated power estimates, and review recently introduced techniques that can improve analysis pipelines and increase power in neuroscience studies

Statistical Speech Segmentation in Tone Languages: The Role of Lexical Tones

First Published May 9, 2017Research has demonstrated distinct roles for consonants and vowels in speech processing. For example, consonants have been shown to support lexical processes, such as the segmentation of speech based on transitional probabilities (TPs), more effectively than vowels. Theory and data so far, however, have considered only non-tone languages, that is to say, languages that lack contrastive lexical tones. In the present work, we provide a first investigation of the role of consonants and vowels in statistical speech segmentation by native speakers of Cantonese, as well as assessing how tones modulate the processing of vowels. Results show that Cantonese speakers are unable to use statistical cues carried by consonants for segmentation, but they can use cues carried by vowels. This difference becomes more evident when considering tone-bearing vowels. Additional data from speakers of Russian and Mandarin suggest that the ability of Cantonese speakers to segment streams with statistical cues carried by tone-bearing vowels extends to other tone languages, but is much reduced in speakers of non-tone languages.The research leading to these results has received funding from: the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC [grant agreement 269502, PASCAL]; the Chilean CONICYT program PIA/BASAL [grant FB0003]; the Alexander von Humboldt Foundation; and the Basque Foundation for Science (Ikerbasque)

Brain regions and functional interactions supporting early word recognition in the face of input variability

Perception and cognition in infants have been traditionally investigated using habituation paradigms, assuming that babies' memories in laboratory contexts are best constructed after numerous repetitions of the very same stimulus in the absence of interference. A crucial, yet open, question regards how babies deal with stimuli experienced in a fashion similar to everyday learning situations-namely, in the presence of interfering stimuli. To address this question, we used functional near-infrared spectroscopy to test 40 healthy newborns on their ability to encode words presented in concomitance with other words. The results evidenced a habituation-like hemodynamic response during encoding in the left-frontal region, which was associated with a progressive decrement of the functional connections between this region and the left-temporal, right-temporal, and right-parietal regions. In a recognition test phase, a characteristic neural signature of recognition recruited first the right-frontal region and subsequently the right-parietal ones. Connections originating from the right-temporal regions to these areas emerged when newborns listened to the familiar word in the test phase. These findings suggest a neural specialization at birth characterized by the lateralization of memory functions: the interplay between temporal and left-frontal regions during encoding and between temporo-parietal and right-frontal regions during recognition of speech sounds. Most critically, the results show that newborns are capable of retaining the sound of specific words despite hearing other stimuli during encoding. Thus, habituation designs that include various items may be as effective for studying early memory as repeated presentation of a single word.European Research Council under European Union 269502 CONICYT-Chile Program PIA/BASAL FB0003 "Progetto strategico NEURAT" from the University of Padua CONICYT-Chile Program PAI/Academia 7913002

Beyond reporting statistical significance: Identifying informative effect sizes to improve scientific communication.

Transparent communication of research is key to foster understanding within and beyond the scientific community. An increased focus on reporting effect sizes in addition to p value-based significance statements or Bayes Factors may improve scientific communication with the general public. Across three studies ( N = 652), we compared subjective informativeness ratings for five effect sizes, Bayes Factor, and commonly used significance statements. Results showed that Cohen's U3 was rated as most informative. For example, 440 participants (69%) found U3 more informative than Cohen's d, while 95 (15%) found d more informative than U3, with 99 participants (16%) finding both effect sizes equally informative. This effect was not moderated by level of education. We therefore suggest that in general, Cohen's U3 is used when scientific findings are communicated. However, the choice of the effect size may vary depending on what a researcher wants to highlight (e.g. differences or similarities)

Dynamic beach response to changing storminess of Unst, Shetland: implications for landing places exploited by Norse communities

We present major new findings on the stability of Norse landing places on the island of Unst, Shetland using a combination of geomorphology, OSL dating, fetch analysis and sediment transport modelling. Islanders needed reliable access to the sea, and exploited sandy beaches as safe landing places. The persistence of beaches was important for long-term continuity of settlement and could be threatened by stormy conditions. Sediment modelling undertaken on two embayments on Unst, Lunda Wick and Sandwick, reveals major differences in the ability of sandy beaches to reform in these embayments after the onset of persistent stormy conditions; sandy beaches can endure under these conditions at Sandwick, but not at Lunda Wick. OSL dating of blown sands at Lunda Wick reveals a history of sand blow events pointing to large scale depletion of beach material throughout the Little Ice Age (beginning circa 1250 CE). This correlates with known sand blows at Sandwick, but here the beach could be replenished from the nearshore environment, something that was more problematic at Lunda Wick. These findings agree with the emerging picture of increased environment pressure from blown sands on communities throughout the North Atlantic and identifies different models of related beach persistence and change