 
Summary: VOLUME 86, NUMBER 10 P H Y S I C A L R E V I E W L E T T E R S 5 MARCH 2001
Effects of Synaptic Noise and Filtering on the Frequency Response of Spiking Neurons
Nicolas Brunel,1
Frances S. Chance,2
Nicolas Fourcaud,1
and L. F. Abbott2
1
LPS, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France
2
Volen Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454
(Received 15 September 2000)
Noise can have a significant impact on the response dynamics of a nonlinear system. For neurons, the
primary source of noise comes from background synaptic input activity. If this is approximated as white
noise, the amplitude of the modulation of the firing rate in response to an input current oscillating at
frequency v decreases as 1
p
v and lags the input by 45±
in phase. However, if filtering due to realistic
synaptic dynamics is included, the firing rate is modulated by a finite amount even in the limit v ! `
and the phase lag is eliminated. Thus, through its effect on noise inputs, realistic synaptic dynamics can
