## End

a. Run the simulation and find the stop-band range of frequencies for the model neural notch filter. Describe what happens for high frequencies.

b. Investigate the effect of noise on the neural notch filter performance. 4.10. This problem investigate the effect of delays in the behavior of the reciprocally inhibited pair of neurons having common excitation shown in text Figure 4.5-2. Delays are added to u3 and u4 in the Simnon program, RECIPIN3.t. That is, the lines, u3 = y3*Do3/tau u4 = y4*Do4/tau are placed with u3 = (Do3/tau) *DELAY (y3 , D3) u4 = (Do4/tau)*DELAY(y4, D4).

a. Use the listed parameters of the program, RECIPIN3.t, in Section 4.5.1 with D3 = D4 = 4 ms to examine the behavior of the model at different input frequencies (vary Ea = A). Does the system generate bursts? Are they in phase? Vary D3 = D4 from 0 to 4 ms, and observe the results.

b. Let Ea = A = 1.5. Investigate the effect of asymmetric delays on the generation of patterned firing on N1 and N2. Specifically, what happens when D3 = 0, D4 = 4, and vice versa?

4.11. In this problem, an RPFM leaky integrator SGL is given a short refractory period by causing each output pulse to raise the firing threshold exponentially. The Simnon program is

CONTINUOUS SYSTEM HP411 "02/01/00. Use Euler integration with delT

STATE v phi

DER dv dphi

" RPFM SGL WITH EXPONENTIAL REFRACTORY PERIOD:

dv = -c*v + c*Vin - z w = IF v > phir THEN 1 ELSE 0 s = DELAY (w, dT) x = w - s y = IF x > 0 THEN x ELSE 0" RPFM output, z = y*phir/dT

dphi = -a*phi + a*Do*z " Refractory increase in firing threshold.

Firing threshold, mV.

SGL generator potential, mV.

" Offset y for plotting

" PARAMETERS: phio: 10 " mV. c:0.2 " r/ms. a: 0.5 " r/ms.

Vo Kr dT Do 