def naka_rushton_no_b(c, a, c50, n):
    """
    Naka-Rushton equation for modeling contrast-response functions. Do not fit baseline firing
    rate (b). Typical for pyramidal cells.
    
    Where: 
        c = contrast 
        a = Rmax (max firing rate)
        c50 = contrast response at 50%
        n = exponent
    """
    return (a*(c**n)/((c50**n)+(c**n)))