Date: Thu, January 18, 14:00-16:00
Place: Room Dw601, D Block, IIS, The University of Tokyo

Invited Speaker: Dr. Juan-Carlos Letelier (The University of Tokyo)

Title: THE NOTION OF SYNCHRONIZATION BETWEEN NEURONAL ASSEMBLIES: 
       An Interesting Counterexample in the Olfactory Epithelium of fishes.

Abstract:  
Neural oscillations, which appear in several areas of the nervous 
system and cover a wide frequency range, are a prominent issue in 
current neuroscience. Extracellularly recorded oscillations are 
generally thought to be a manifestation of a neural population with 
synchronized electrical activity due to coupling mechanisms. The 
vertebrate olfactory neuroepithelium exhibits beta-band oscillations, 
termed peripheral waves (PWs) in their population response to odor 
stimulation. Here we examine PWs in the channel catfish and propose 
that their properties could be explained as the superposition of 
uncoupled (i.e., asynchronous) oscillators. Our model shows that the 
intriguing random pattern of amplitude modulated PWs could be 
explained by Rayleigh fading, an interference phenomenon well-known in 
physics and recognizable using statistical methods and signal 
analysis.  We are proposing mathematical fingerprint to characterize 
neural signals generated by the addition of random phase oscillators. 
Our interpretation of PWs as arising from uncoupled oscilators could 
be generalized to other neuronal populations as it suggests that 
neural oscillations, detected in LFP recordings within a narrow 
frequency band do not necessarily originate from synchronization 
events.