23 March 2012
Presentation type: Project
None
Presentation type: Science
Petra Vetter, PhD, Centre for Cognitive Neuroimaging (CCNi), Institute of Neuroscience and Psychology, University of Glasgow
" Contextual and multi-sensory influences on early visual cortex activity"
Traditionally, early visual cortex has been thought to be mainly involved in the processing of simple visual features. Here I will present results from two fMRI studies showing that activity patterns in early visual cortex contain information from sounds, imagery and emotional context. Using multivariate pattern classification techniques, we decoded natural sounds and imagery content from the activity patterns of early visual cortex in the absence of any visual stimulation. In the second study, we decoded auditorily presented emotional context in early visual cortex while subjects viewed an emotionally ambiguous visual display of interacting point light walkers. Both studies demonstrate that early visual cortex is affected by contextual information in a content-specific manner via cortical feedback from multi-sensory and higher level brain areas. The results suggest that early visual cortex may be able to integrate contextual information, possibly for the purpose of prediction, and may do more than basic visual feature detection.
30 March 2012
Presentation type: Project
None
Presentation type: Science
Tim Vogels
" Inhibitory plasticity balances excitation and inhibition in sensory pathways and memory networks"
The balance of excitatory and inhibitory membrane currents recorded in neurons during stimulated and spontaneously active network states has been the focus of many recent experimental and theoretical studies. The function of such balance states has been hypothesized to enable fast, stable and diverse network responses, to amplify the response to certain stimuli, or to allow the establishment of functional network architectures by means of dynamically controlling this balance in distinct groups of cells. Despite the recent interest in these phenomena, no mechanism has been brought forward that would allow the establishment of such balanced networks.
Using networks of integrate and fire neurons, we show that spike timing-dependent plasticity rules that act on inhibitory synapses can succeed in establishing globally balanced networks. Additionally, we show that in a feedforward architecture, the same learning rules establish a detailed balance in each cell. We show that the mechanism we put forward provides an explanation for the sparse firing patterns observed in response to natural stimuli and fits well with a recently observed interaction of excitatory and inhibitory receptive field plasticity. The introduction of inhibitory plasticity in suitable recurrent networks provides a homeostatic mechanism that leads to asynchronous irregular network states. Further, it can accommodate synaptic memories with activity patterns that become indiscernible from the background state, but can be re-activated by external stimuli. Our results suggest an essential role of inhibitory plasticity in the formation and maintenance of functional cortical circuitry.
6 April 2012
Easter holidays
13 April 2012
SPM course
20 April 2012
Polona Pozeg: CANCELLED
27 April 2012
Presentation type: Science
Narly Golestani
" Neural bases of language learning and expertise"
In previous work on language and the brain in adults, we have shown that there are large normative individuals differences in
foreign speech sound learning, and that such individual differences are accompanied by both functional and structural brain differences. Evidence for structural differences is especially striking since brain structure can be assumed to be relatively more
stable than brain function, which it can be expected to change after only very short periods of training / learning. This leads to the question of the relative influences of pre-existing, possibly ‘innate’ brain structural differences between individuals which might predict domain-specific language capacities, and of experience-dependent plasticity following systematic differences in learning. In a recent brain imaging study, we found complimentary evidence for both experience-dependent structural plasticity in phonetics experts, and aspects of brain anatomy that likely pre-date the expertise training. We also present preliminary longitudinal evidence for experience-dependent plasticity in a different group of language experts: simultaneous language interpreters in training. Our results suggest that both pre-existing, possibly innate factors and environment influences (learning) play a role in brain structure and in specific language-
related skills, with different relative contributions in different brain areas. More generally, innate factors and the environment likely interact in that the environment itself is partly selected based on genetically influenced preferences
04 May 2012
Presentation type: Project 15:30 - 16:00
no presentation
Presentation type: Science 16:00 - 16:30
Jürgen Dukart, LREN, CHUV
"Dissociating memory networks in early Alzheimer’s disease and Frontotemporal lobar degeneration - A combined investigation of regional hypometabolism and atrophy"
In our study we dissociate neural correlates of memory disorders in Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD). Using a whole brain approach, we compute correlations between test performance and FDG-PET and MRI data separately in each dementia group. We find that indistinguishable clinical performance in memory tests in AD and FTLD is associated with different neural correlates in both dementia syndromes.
11 May 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: Science 16:00 - 16:30
Marzia De Lucia
"Global mismatch negativity does not require awareness of stimulus regularity"
Auditory evoked potentials (AEPs) are informative of intact brain functions in comatose patients. One marker is provided by the differerential AEPs responses to standard and rare sounds in a mismatch negativity (MMN) paradigm. MMN induced by the repetition of groups of sounds (global MMN) has been reported only when subjects were aware of the regularity (Bekinschtein et al. 2009). Here I challenge this evidence by showing evidence of global MMN on postanoxic comatose patients who underwent therapeutic hypothermia.
18 May 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: tba 16:00 - 16:30
tba
"tba"
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25 May 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: Science 16:00 - 16:30
Joseph Ghika
"Paleoneurology: neurodegenerative age-related diseases rely on the interaction of epigenetics and brain areas recently developed by Homo sapiens"
Paleoneurology gives the key for understanding the mechanisms underlying the neurodegeneration of recently evolved human brain regions including the focal, asymmetrical or systemic character of neurodegeneration, the pathologic heterogeneity/overlap of syndromic presentations associating gait, hand, language, cognition, mood and behavior disorders.
1 June 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: Science 16:00 - 16:30
Wietske van der Zwaag
"The hand representation in the human cerebellum overlaps with the digit representations"
The human cerebellum contains a relatively little studied, double homunculus. Within these homunculi, body parts are known to show overlap at millimeter resolutions. I will present the results of a study where we mapped the layout of individual digits and the hand using fMRI and evaluated the overlap between these representations.
8 June 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: Science 16:00 - 16:30
Corrado Corradi-Dell'Acqua
"tba"
tba
15 June 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: tba 16:00 - 16:30
tba
"tba"
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22 June 2012
Presentation type: Project 15:30 - 16:00
tba
Presentation type: Science 16:00 - 16:30
Giorgio Innocenti
"Different connectivity of cortical areas in primates"
tba
29 June 2012
Presentation type: Project 15:30 - 16:00
no project presentation this week
Presentation type: Science 16:00 - 16:30
Dr Jonas Richiardi
"Taking fMRI functional connectivity graphs beyond group statistics" Whole-brain connectivity information is becoming increasingly popular with neuroimagers, and for good reasons: it provides complementary information to statistical activation maps, and enables fundamental insights into the network organization of the brain in terms of information flow, resilience, efficiency, or modularity. Furthermore, it is now gaining importance for clinical applications.
“Connectivity-based decoding in multiple sclerosis" The methods-oriented first part of the talk will focus on an emerging technique we recently proposed, connectivity-based decoding. After a whole-brain regional functional connectivity graph has been established, the problem can be cast as a weighted graph classification task. We will show that the graphs of interest form a restricted class of graphs whose properties encourage the use of modern graph embedding methods. We will present several vector space representations of graphs that are suitable for the class of graphs of interest, and discuss the application of machine learning to such embeddings, enabling predictive inference at the single subject level rather than group-level inference. The applications-oriented second part of the talk will present results using the technique, in particular a recently completed study of multiple sclerosis (MS), where we show good sensitivity to MS and are able to predict disease status of single subjects from resting-state connectivity alterations. We will also present a new type of summary plot representing discriminative connectivity alterations in two dimensions.
6 July 2012
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Presentation type: Project 15:30 - 16:00
no project presentation this week
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Presentation type: Science 16:00 - 16:30
Sandra Da Costa
"Tuning in to sound: frequency-selective attentional filter in human primary auditory cortex"
Cocktail parties, busy streets, and other noisy environments pose a difficult challenge to the auditory system: how to focus attention on
selected sounds while ignoring others? [1] Neurons of primary auditory cortex, which are sharply tuned to sound frequency, could help solve this problem by filtering selected sound information based on frequency-content. To investigate whether this occurs, we used high-resolution fMRI at 7 Tesla to map the fine-scale frequency-tuning (1.5 mm isotropic resolution) of primary auditory areas A1 and R in six human participants. Then in a selective attention experiment, participants heard low (250 Hz) and high (4000 Hz) frequency streams of tones presented at the same time and were instructed to focus attention onto one stream vs. the other, switching back and forth every 30s. Attention to low frequency tones enhanced neural responses within low frequency-tuned voxels relative to high, and when attention switched the pattern quickly reversed. Thus, like a radio, human primary auditory cortex is able to tune into attended frequency channels and can switch channels on demand.
14 September 2012
Presentation type: Project
Avinash Ramynead, Laboratory of Neurology and Imaging of Cognition, CMU Geneva
"The impact of unfinished business on subsequent ruminations during wakefulness and sleep"
This study investigates the spontaneous reactivation of neuronal activity associated with unfinished tasks (in this case, unfinished video games). Participants have been asked to complete two tasks whose neural activity is easily distinguishable. We used a combined fMRI + EEG approach to investigate whether an unfinished task results in its spontaneous brain reactivation during wakefulness and different stages of sleep. EEG was used to determine in which stages of sleep the participants were going through while in the scanner. The next step is to score sleep and to do further contrast analysis. Classifiers are currently being trained in parallel at the EPFL to identify specific patterns of activations..
Presentation type: Science
cancelled
21 September 2012
Presentation type: Project
Valerie Beaud, LREN, DNC-CHUV, Lausanne
"Continuum and components of motivational disorders"
Motivational disorders include, on a continuum, several syndromes in particular apathy, avolition and auto-activation deficit. These disorders are based on emotional, behavioural and cognitive components. The objective of this study is to determine wich areas of the circuit connecting the CPF to GDB can cause these specific syndromes, in reference to these three components.
Presentation type: Science (hosted by Ferath Kherif)
Domenica Bueti, FENL, CHUV, Lausanne
"Learning about Time: Plastic Changes and Interindividual Brain Differences"
In this MRI work we studied brain plasticity during time learning. We show that in humans learning to discriminate visual time intervals in the millisecond range is associated with functional and structural changes in sensory and motor brain regions. These brain changes predict and correlate with individual learning abilities.
28 September 2012
Presentation type: Project
Sara Lorio, LREN, DNC-CHUV, Lausanne
"T2 mapping in the human brain at ultra-high field" - S. Lorio, B. Draganski, J. Marques
Presentation type: Science (hosted by Bogdan Draganski)
Antoine Lutti, Wellcome Trust Centre for Neuroimaging, UCL London, UK
"Multi-parameter quantitative mapping – towards in-vivo histology"
Standard anatomical brain imaging using MRI (e.g. T1-weighted imaging) offers good tissue contrast and is commonly used for macroscopic morphological studies such as Voxel Based Morphometry (VBM). However, image intensity and contrast in standard anatomical scans contain mixed contributions from several MR parameters and are strongly affected by receive and transmit RF inhomogeneities.
Quantitative mapping measures the MR parameters that govern the image intensity and contrast. The quantitative estimates are bias-free and allow for direct and quantitative comparisons between tissue types. Quantitative mapping facilitates longitudinal and multi-centre studies and provides a powerful insight into tissue microarchitecture.
I will present a set of MR ‘multi-parameter mapping’ scanning protocols allowing for the efficient and robust mapping of multiple MR parameters (Magnetization Transfer, T1, T2* and Proton Density). High-resolution (1mm/800um) whole-brain mapping can be achieved in a total acquisition time of 20-30 mins. I will demonstrate the robustness of the method and illustrate how the quantitative maps can be used to gain an insight into brain tissue properties and biophysical processes. Examples will include myelin mapping for in-vivo histology and ageing of brain tissues. I will end this talk by presenting some recent results from the development of 3D EPI pulse sequences for fMRI which offer promising prospects in terms of data quality and acquisition speed.
5 October 2012
Presentation type: Project
Valerie Zufferey, LREN, DNC-CHUV, Lausanne
"Cortico-hippocampal-striatal systems interaction during dynamic probabilistic learning" - V. Zufferey, S. Adaszewski, F. Kherif
Presentation type: Science (hosted by Maria Knyazeva)
Sara L. Gonzalez Andino, Electrical Neuroimaging Group, Department of Clinical Neurosciences, University of Geneva
"The mammalian brain seen as an evolution shaped metamaterial"
Experience and learning lead to plasticity induced changes in both, the functional organization of neuronal circuits and the brain's physical architecture, i.e., its anatomy. Structural changes in human tissue often co-exist with cognitive impairments and disturbances of the electromagnetic brain activity. The prevalent view, which basically attributes the emergent cognitive abilities of mammal’s to the numerous neuronal networks composing their brains and their connectivity, fails to relate the macroscopic architecture of neural tissue to its cognitive function or to explain why cognitive deficits and electromagnetic fields disturbances ensue from architectural alterations.
In this talk – oriented to a neurobiological audience - we will first introduce metamaterials to illustrate the tight links between function and structure appearing in non-living matter. From a metamaterial perspective, the idea of artificially reproducing cognition by simply interconnecting cells (e.g., BlueBrain) is unlikely to succeed as it ignores architectural factors contributing to emergence. We think that metamaterials might be a successful path to artificially implement cognition and memory.
12 October 2012
Presentation type: Project
No project presentation
Presentation type: Science (hosted by Ferath Kherif)
Jonas Richiardi, EPFL & HUG Geneva
Connectivity-based decoding in multiple sclerosis
We will present results using our recently proposed connectivity decoding technique, in particular a recently completed study of multiple sclerosis (MS), where we show good sensitivity to MS and are able to predict disease status of single subjects from resting-state connectivity alterations. We will also present a new type of summary plot representing discriminative connectivity alterations in two dimensions.
19 October 2012
Presentation type: Project
tba
"tba"
tba.
Presentation type: Science (hosted by Micah Murray)
Jérémie Lefebvre, Department of Basic Neuroscience - University Geneva
"Additive noise in delayed recurrent systems"
Delayed feedback is a key feature of neural microcircuits and plays a crucial role in sensory processing. Subject to stimulation, recurrent network oftentimes undergo rhythmic activity or other types of transitions, that have been shown to be relevant to coding. Yet, how the dynamics in such circuit architectures are impacted by temporal fluctuations is not clear. I will show several examples where such dynamic transitions occur and expose the impact of additive noise on the stability of activity patterns.
26 October 2012
Presentation type: Project
tba
"tba"
tba.
Presentation type: Science (hosted by Jürgen Dukart)
Arseny Sokolov, Neurology, DNC-CHUV, Lausanne
"Cerebellar involvement in action observation: Lesion findings, underlying effective and structural connectivity"
The cortical network for action observation has been extensively studied but the role of other brain structures remains unclear. Lesion data revealing engagement of the left lateral cerebellum are in agreement with fMRI findings. Dynamic causal modelling and diffusion tensor imaging provide novel insights on cerebro-cerebellar connectivity.
2 November 2012
Presentation type: Project
no Project presentation
Presentation type: Distinguished speaker series (hosted by Bogdan Draganski)
Prof. Jean-Philippe Thiran, EPFL, Signal Processing lab (LTS5) & UNIL-CHUV, Dept of Radiology
"Image segmentation by fusion of multiple atlases : review and some contributions"
In this talk we will present the state-of-the-art in atlas-based segmentation of medical images by fusion of labels from multiple atlases. We will then show how those methods can be naturally improved by adding more prior knowledge on the smoothness thanks to the Markov Random Fields theory. Finally, we will propose two new fusion schemes. All those methods will be illustrated and compared in the framework of the segmentation of lymph nodes in head&neck radiotherapy planning.
Joint work with S. Gorthi (EPFL), Dr M. Bach Cuadra (UNIL) and Prof. A.A. Allal (Hopital Fribourgeois - radioltherapy).
9 November 2012 **** Note: starting at 3:30pm
Presentation type: Project
no Project presentation
Presentation type: Distinguished speaker series (hosted by Bogdan Draganski)
Serge Vulliemoz, Neurologie HUG, Geneva
"Mapping epileptic networks in the human brain"
Epilepsy is one of the most frequent chronic neurological disorder. A better understanding of neuronal networks involved in epileptic activity affecting the human brain would allow to enhance our understanding of this condition. In some patients with pharmaco-resistant epilepsy who are candidates for epilepsy surgery, the precise localisation of important nodes of the network and their connections is critical for the success of the procedure. I will describe the mapping of epileptic networks in the brain using electric source localisation based on high density EEG as well as simultaneous EEG and functional MRI. Moreover, the opportunity to record intracranial EEG and follow-up after brain surgery in selected patients offers unique possibilities for validating new imaging techniques that benefit to other area of neuroimaging research.
16 November 2012
Presentation type: Project
no Project presentation
Presentation type: Science
Vitali Chicherov, Laboratory of psychophysics, Brain Mind Institute, EPFL
"Global aspects of low-level vision: the EEG study of crowding"
Traditional models of visual processing assume that information flows from low- to high-level visual areas undergoing increasingly complex processing and, finally, reaching consciousness. In the spirit of this view, crowding, the failure of object recognition due to flanking elements, is traditionally explained by detrimental effects of flankers at the low-level stage. Here, I will show that global aspects of the stimulus, e. g. perceptual grouping of the target and flankers, plays a crucial role in crowding. Using high density EEG, I will show that the P1 wave reflects stimulus layout whereas the N1 wave reflects crowding. These results indicate that crowding emerges in time consuming, recurrent processing.
30 November 2012
Presentation type: Project
no Project presentation this week
Presentation type: Clinical neuroscience meets basic neuroscience (hosted by Bogdan Draganski)
Lorenz Hirt, Service Neurologie, DNC-CHUV, Lausanne
"Rodent models to study stroke"
Our lab is using in vitro and in vivo stroke models to investigate several neuroprotective molecules. I will present some of our work on the c-Jun N-terminal kinase inhibitor D-JNKI1 and the metabolite L-lactate as well as some data on endogenous tolerance. Finally, I will show some recent data on potential stroke biomarkers and their use in stroke analysis.
7 December 2012
Presentation type: Project
Antonia Thelen & Micah Murray
"Hot spots of auditory-visual integration"
Anatomical studies have revealed the existence of monosynaptic projections between low-level auditory and visual cortical regions in animals. Whether these findings extend to humans remains an open issue. Also, the functionality and behavioral relevance of the information they relay between primary sensory areas, is unknown.
The aim of the project is to tap into such auditory-visual interactions, through high-density EEG recordings and psychophysical investigations.
Presentation type: Distinguished speaker series (hosted by Bogdan Draganski)
Gregoire Courtine, Centre for neuroprostethics and Brain Mind Institute, EPFL, Lausanne
"Inspiring New Thinking to Restore Function after Spinal Cord Injury"
Functional restoration after paralyzing spinal cord injury (SCI) has been interpreted as the need to promote long-distance regeneration of severed fibers to their original targets. A radically new and more immediate approach may instead capitalize on the remarkable capacity of spared neuronal systems to reorganize through use-dependent mechanisms. Here, I will introduce a combinatorial training paradigm that fully exploits this therapeutic concept. This neurorehabilitation program combines an electrochemical neuroprosthesis and a robotic postural interface that restored cortical control over complex locomotor movements through the extensive remodeling of spared supraspinal and intraspinal pathways in rats with a paralyzing SCI. I will discuss the implication of these findings for the design of strategies to return function in severely paralyzed patients.
tba
14 December 2012
Project presentation
Youri Messen-Jaschin
"Optical illusion arts meets science"
Clinical neuroscience meets basic neuroscience (hosted by Bogdan Draganski)
David Benninger, Service Neurologie, DNC-CHUV, Lausanne
"Non-invasive Brain Stimulation for Parkinson's Disease"
Transcranial magnetic stimulation (TMS) has advanced our knowledge of pathophysiology and demonstrated therapeutic potential in Parkinson’s disease (PD). Current concepts and ongoing research will be discussed.
