code: def dspmt(t, peak_delay=6, under_delay=16, peak_disp=1, under_disp=1,
            p_u_ratio=6):
      
      t = np.asarray(t)
      aryRsp1 = spmt(t, peak_delay=peak_delay, under_delay=under_delay,
                     peak_disp=peak_disp, under_disp=under_disp,
                     p_u_ratio=p_u_ratio)
      aryRsp2 = spmt(t-1, peak_delay=peak_delay, under_delay=under_delay,
                     peak_disp=peak_disp, under_disp=under_disp,
                     p_u_ratio=p_u_ratio)
  
      return aryRsp1 - aryRsp2
docs: SPM canonical HRF derivative, HRF derivative values for time values `t`
  
      Parameters
      ----------
      t : array-like
          vector of times at which to sample HRF
  
      Returns
      -------
      hrf : array
          vector length ``len(t)`` of samples from HRF at times `t`
  
      Notes
      -----
      [1] This is the canonical HRF derivative function as used in SPM.
      [2] It is the numerical difference of the HRF sampled at time `t` minus the
      values sampled at time `t` -1
  
      References:
      -----
      [1] http://nipy.org/
      [2] https://github.com/fabianp/hrf_estimation