simtb_balloon_model

 simtb_balloon_model()  - Nonlinear balloon model to generate TCs

 Usage:
  >> [tc] = simtb_balloon_model(eTC, P, x);

 INPUTS:
 eTC          = [nT x 1] event vector
 TR           = repetition time (in seconds)
 P (OPTIONAL) = vector of parameters for the BOLD generation model 

 OUTPUTS:
 tc   =  [nT x 1] component time course

 see also: simtb_TCsource()
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 SEE:
 Friston, A Mechelli, R Turner, CJ Price, 2000. Nonlinear responses in fMRI:
 the Balloon model, Volterra kernels, and other hemodynamics. Neuroimage.

 Buxton, R.B. and Wong, E.C. and Frank, L.R. 1998. Dynamics of blood flow
 and oxygenation changes during brain activation: the balloon model. Magnetic Resonance in Medicine.
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 hemodynamic model

 INPUTS:
   eTC    - input (neuronal activity)                    (eTC)
   P      - free parameter vector
   P(1) - signal decay                                   d(ds/TR)/ds)
   P(2) - autoregulation                                 d(ds/TR)/df)
   P(3) - transit time                                   (t0)
   P(4) - exponent for Fout(v)                           (alpha)
   P(5) - resting oxygen extraction                      (E0)
   P(6) - echo time   (seconds)                          (TE)
   P(7) - input efficacies                               d(ds/TR)/du)

   TR - repeat time (sec)                                (TR)

 OUTPUTS:
 tc      - output BOLD signal