The emergence of a compass information in the fly brain
The ability to navigate in a spatially extended environment is an essential
function for species ranging from insects to mammals. If many interesting
facts are known about the phenomenology of navigation, much less is understood
about the neural mechanisms that support these abilities. Recent results from
neural activity recordings in the fruit fly brain have identified a neural
population that sustains an internal representation of heading direction. These
neurons have dendrites arranged in a ring-shaped structure in the fly brain.
At any time, the recorded dendritic activity is spatially localized on this
ring with the activity bump tracking both rotations of surrounding visual
landmarks as well as the fly’s own rotational movements in the dark. Moreover,
the activity persists in the absence of external stimuli, ie in the dark or in
the absence of self-motion. This system provides an unprecedented opportunity
to test theoretical models of persistent activity and information processing in
neural networks. More precisely, I will show how one can model the dynamics of
this bump of activity and provide hypothesis on the essential feature of a
neural network that can explain the observed dynamics. With the help of
computer simulations, we explore the main properties of the network and provide
interesting predictions on the system. This study have potential applications
for other living organisms. For instance neurons having similar properties,
called head direction cells, have been characterized in mammals. However, due to
experimental limitations in those organisms, it has been very challenging to
come up with a network level understanding of the mechanisms generating those
properties.
HHMI Janelia Research Campus
Sandro Romani’s lab
19700 Helix Drive
Ashburn, Virginia 20147 (USA)
Invité par A.MALVACHE
Salle de conférence INMED, lundi 10 juillet 2017 à 11h