PSL-UCL workshop on sensory systems in complex environments

London, 25-26 June 2015

Organized by Maria Chait, Peter Neri, Pascal Mamassian, Daniel Pressnitzer, Alain de Cheveigné

Lecture theatre, UCL Ear Institute, 332 Gray's Inn Road, WC1X 8EE, London, close to St Pancras International Station (Eurostar), Map .

This workshop brings together researchers and students from UCL and PSL. It is loosely focused on sensory systems, both audition and vision, both biological and artificial, and also open to a wider scope of scientific and technological themes. The aim is to foster future exchanges and collaboration between UCL and PSL research teams.

Provisional list of participants:

Joerg Albert, Ear Institute (UCL) Karim Benchenane, ESPCI (PSL), Fred Dick, Birkbeck-UCL Centre for Neuroimaging (UCL), Alan Johnston, Department of Experimental Psychology (UCL), Christian Lorenzi, ENS (PSL), Pascal Mamassian, ENS (PSL), Pascal Martin, Institut Curie (PSL), Daniel Pressnitzer, ENS (PSL), Stuart Rosen, Hearing & Phonetic Sciences (UCL), Maneesh Sahani, Gatsby Computational Neuroscience Unit (UCL), Aman Saleem, Institute of Ophthalmology (UCL), German Sumbre, IBENS, ENS (PSL), Mickael Tanter, ESPCI (PSL).

Invited discussants:
Daniel Bendor, Department of Experimental Psychology (UCL), Jennifer Bizley, Ear Institute (UCL), Yves Boubenec, ENS (PSL), Matteo Carandini, Institute of Opthalmology (UCL), Maria Chait, Ear Institute (UCL), Alain de Cheveigné, ENS (PSL), Vincent de Gardelle, (CNRS), John Greenwood, Experimental Psychology (UCL), Ken Harris, Institute of Neurology (UCL), Nicolas Lesica, Ear Institute (UCL), Jennifer Linden, Ear Institute (UCL), Isabelle Mareschal, Biological and Chemical Sciences (Queen Mary), David McAlpine, Ear Institute (UCL), Peter Neri, ENS (PSL), D Sam Schwarzkopf, Department of Experimental Psychology (UCL), Marty Sereno, (UCL), Sam Solomon, Department of Experimental Psychology (UCL), Francois Vialatte, ESPCI (PSL), Biao Yang, Department of Civil, Environmental and Geomatic Engineering (UCL).

Invited students:
Vincent Adam, Gatsby Institute (UCL), Thomas Andrillon, ENS (PSL), Dorothée Arzounian, ENS (PSL), Huriye Atilgan, Ear Institute (UCL), Nicolas Barascud, Ear Institute (UCL), Leonardo Barbosa, ENS (PSL), Jonathan Batten (Birkbeck University), Anissa Bellahcen ENS (PSL), Charlie Déméné, ESPCI (PSL), Gioia De Franceschi, Experimental Psychology (UCL), Mario Dipoppa, Institute of Neurology (UCL), Antoine Gaume, ESPCI (PSL), Nikos Gekas, ENS (PSL), Hadrien Jean, ENS (PSL), Hi-Jee Kang, ENS (PSL), Julie Lefort, ESPCI (PSL), Francesca Mastrogiuseppe, ENS (PSL), Jane Mattley, Ear Institute (UCL), Nihaad Paraouty, ENS (PSL), Theo Petsas, Ear Institute (UCL), Emmanuel Ponsot (IRCAM), Sylvia Schröder, Institute of Opthalmology (UCL), Camille Tardieu, Ear Institute (UCL), Mélanie Tobin, Institut Curie (PSL). Stephen Town, Ear Institute (UCL), Eszter Vertes, Gatsby Institute (UCL), Sijia Zhao, Ear Institute (UCL).


Thursday 25:

8:30 COFFEE & croissants
9:10 (40') Joerg Albert
9:50 (40') Pascal Martin
10:30 (30') COFFEE
11:00 (40') Aman Saleem
11:40 (40') Karim Benchenane
12:20 (80') LUNCH
13:40 (40') Fred Dick
14:20 (40') Mickael Tanter
15:00 (30') COFFEE
15:30 (40') Christian Lorenzi
16:10 (40') Stuart Rosen

Friday 26:

9:00 COFFEE & croissants
9:30 (40') Alan Johnston
10:10 (40') Pascal Mamassian
10:50 (30') COFFEE
11:20 (40') German Sumbre
12:00 (40') Daniel Pressnitzer
12:40 (70') LUNCH
13:50 (40') Maneesh Sahani
14:30 (60') THE FUTURE
15:30 END
16:15 Ken Harris talk at FIL

Each 40' slot comprises a 20-30' minute talk and a 20-10' discussion.

Talkers, titles and abstracts:

Joerg Albert
The Drosophila Antennal Ears as Universal Tools for the Study of Sensory Biology

The antennal ears of Drosophila are a powerful model system for the molecular dissection of mechanosensation, and specifically of mechanotransduction. Some of the key principles of vertebrate ears, such as e.g. nonlinear compression and amplification, have been demonstrated for fly hearing and numerous genes have been identified that play specific roles within the auditory system. The ears of different Drosophila species differ in their spectral tuning to match differences in the spectral composition of the conspecific courtship songs. The presentation will recapitulate previous findings and highlight ongoing riddles and controversies. Particular effort will be spent on making suggestions as to how the study of the fly's ear can contribute to our general understanding of sensory organ operation, homeostasis and maintenance.

Pascal Martin
The hair-cell bundle as a mechanical antenna and amplifier for hearing.

I will review micromechanical experiments at the level of the cellular microphone of the inner ear - the hair cell - whose function is to transduce sound-evoked vibrations into electrical nervous signals. I will discuss the origin of stiffness and drag of the hair bundle, a tuft of cylindrical protrusions that protrudes from the apical surface of each hair cell, and show how these physical parameters can influence the cell's characteristic frequency of mechanosensitivity. A dynamical interplay between mechanosensitive ion channels, molecular motors, and calcium feedback results in spontaneous oscillations of the hair-cell bundle. Oscillations allow the hair cell to actively resonate with its mechanical input at the expense of nonlinear distortions with properties that are characteristic of auditory perception. Our results promote a general principle of sound detection that is based on nonlinear amplification by self-sustained "critical" oscillators in the inner ear, i.e. active dynamical systems that operate on the brink of an oscillatory instability called a Hopf bifurcation.

Karim Benchenane
Explicit memory creation during sleep: a causal role of place cells in navigation

Hippocampal place cells assemblies are believed to support the cognitive map, and their reactivations during sleep are thought to be involved in spatial memory consolidation. By triggering intracranial rewarding stimulations by place cell spikes during sleep, we induced an explicit memory trace, leading to a goal-directed behavior toward the place field. This demonstrates that place cells' activity during sleep still conveys relevant spatial information and that this activity is functionally significant for navigation.

Aman Saleem
Hippocampal representation of spatial decisions in uncertain environments

I will present recent results regarding the activity of place cells when sensory uncertainty is varied. I recorded extracellular CA1 activity while animals performed a navigation task in a virtual environment, and controlled the sensory uncertainty by varying the visual contrast at which the virtual environment was presented. We find that increasing uncertainty does not change the average firing rate or population spread of activity. However, the population of neurons make more errors at representing the environment with growing uncertainty. Further, the behavioural errors made by the animals are directly correlated with errors in the hippocampal representation.

German Sumbre
A neuronal correlate of visual motion perception in the zebrafish optic tectum

Following coherently moving visual stimuli (conditioning stimulus, CS), many organisms perceive, in the absence of physical stimuli, illusory motion in the opposite direction, an phenomenon known as the motion aftereffect (MAE). Here we use MAE as a tool to study the neuronal mechanisms underlying visual motion perception in zebrafish. Taking advantage of the zebrafish optokinetic response as an indicator of visual motion perception, we showed that zebrafish larva perceives MAE. Optogenetic blockage of eye movements during CS did not prevent the emergence of MAE. Using two-photon calcium imaging of behaving GCaMP3 larvae we found sustained rhythmic activities among direction-selective (DS) tectal neurons that were associated with the perception of MAE. Additionally, CS induced habituation of DS neurons in the CS direction in the tectum but not in the retina. Finally, an empirical mathematical model reproduced the MAE phenomenon suggesting a functional neuronal circuit capable of generating perception of visual motion.

Mickael Tanter
fUltrasound: a new neuro-imaging modality

Christian Lorenzi
Auditory processing of temporal information: Effects of age and cochlear damage

Over the last decades, a wealth of studies have demonstrated that temporal envelope and temporal fine structure play an important role in speech and music perception. We will review recent behavioral work conducted by our team, aiming to clarify the effects of cochlear damage and ageing on the auditory processing of temporal envelope and temporal fine structure cues, respectively. The results should be help designing better screening tools for ENT clinicians and audiologists, and help improving signal processing for digital hearing aids.

Stuart Rosen
Developmental aspects of perceiving speech in 'noise'

We rarely hear speech in quiet, yet much remains to be learned about how the ability to understand speech in the presence of other sounds develops through childhood. I will review a number of studies comparing children in primary school to young adults in their abilities to understand simple sentences in the presence of various kinds of maskers, mostly consisting of other speech. Perhaps the most striking result is that younger children appear to be much more affected by the presence of background speech than adults are, and this ability is not yet fully developed at the end of primary school (age 11).

Fred Dick TBA

Daniel Pressnitzer TBA

Alan Johnston
Computing global motion from local signals

The aperture problem limits the information that can be extracted from a local analysis of image motion. This means information needs to be integrated across space to compute the global motion of objects. We can study this process using Gabor arrays. We show that motion induced position shifts and motion drag is computed after global motion computation and consider a new way to combine the local velocities - the harmonic vector average. Finally I will introduce a new stimulus that shows the visual system considers more complex motion patterns than global translation before it comes to a final resolution of the aperture problem.

Pascal Mamassian
The psychophysics of visual confidence

Maneesh Sahani
Probabilistic inference in complex environments

Opportunities for UCL - PSL collaboration

This slot is to discuss opportunities for collaboration between UCL and PSL labs, and for the exchange of scientists and students across the Channel. Funding for bilateral collaboration, european projects, etc. Joint studentships and training programmes (masters, PhD, etc.). Bench fees, scholarships, travel grants. What are the converging and complementary scientific interests? And so on...

This workshop is funded by University College London and PSL Research University, ANR-11-0001-02 PSL* and ANR-10-LABX-0087.