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HDR varies across regions (plumbing or neuronal?). Can FMR adaptation be at least partially due to hemodynamics?. R. M. Birn, Z. Saad, P. A. Bandettini, Spatial heterogeneity of the nonlinear dynamics in the fMRI BOLD response. NeuroImage , 14 : 817-826, (2001).
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HDR varies across regions (plumbing or neuronal?)
Can FMR adaptation be at least partially due to hemodynamics?
R. M. Birn, Z. Saad, P. A. Bandettini, Spatial heterogeneity of the nonlinear dynamics in the fMRI BOLD response. NeuroImage, 14: 817-826, (2001). R.M. Birn, P. A. Bandettini, The effect of stimulus duty cycle and "off" duration on BOLD response linearity. NeuroImage, 27, 70-82 (2005) A. S. Tuan, R. M. Birn, P. A. Bandettini, G. M. Boynton, Differential MEG and fMRI responses to visual stimulation onset rate (in preparation)
R. M. Birn, (2001) NeuroImage, 14: 817-826. Increases: linearity Logothetis et al. (2001) Nature, 412, 150-157. R.M. Birn, et al. Neuroimage 14, 817-26, 2001 P. A. Bandettini et al, (2001) Nature Neuroscience, 4: 864-866.
8 f (SD) 6 4 0 10 20 30 40 0 10 20 30 40 2 0 1 2 3 4 5 Stimulus Duration -2 60 8 f (SD) 40 6 4 20 2 0 2 4 6 8 10 0 1 2 3 4 5 Stimulus Duration nonlinearity -2 Nonlinearity – visual task R.M. Birn, et al. Neuroimage 14, 817-26, 2001
0 10 20 30 40 0 10 20 30 40 Nonlinearity – motor task 8 f (SD) 6 4 2 0 1 2 3 4 5 Stimulus Duration 40 8 f (SD) 6 20 4 2 0 5 10 15 20 25 nonlinearity 0 1 2 3 4 5 Stimulus Duration R.M. Birn, et al. Neuroimage 14, 817-26, 2001
Reproducibility Visual task Motor task Nonlinearity1 Nonlinearity1 Nonlinearity2 Nonlinearity2 Experiment 1 Experiment 2 Experiment 1 Experiment 2 R.M. Birn, et al. Neuroimage 14, 817-26, 2001
0 2 4 8 12 16 20 2000ms 1000ms Signal 500ms 250ms 0 5 10 15 time (s) 10 Amplitude (%) 5 0 0 1 2 3 4 5 Stimulus Duration (s) Estimated neuronal input Contrast Reversing Checkerboard Estimated Neuronal Activity
100 Signal 50 time (s) 0 0 1 2 3 3200ms 1600ms 800ms 400ms 200ms 100ms 50ms Measured Amplitudes 3 2 Amplitude (%) 1 0 0 1 2 3 Stimulus Duration (s) 0 2 4 6 8 10 12 14 Estimated neuronal input Static Grating Estimated Neuronal Activity time(s)
Decreases: linearity R.M. Birn, P. A. Bandettini. NeuroImage,
Increases: duty cycle R.M. Birn, P. A. Bandettini, The effect of stimulus duty cycle and "off" duration on BOLD response linearity. NeuroImage, 27, 70-82 (2005)
Model – Neuronal effects refractory period OFF response adaptation
refractory period OFF response adaptation c d e f 0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 2 2 2 2 Amplitude Amplitude Amplitude Amplitude 1 1 1 1 0 0 0 0 0 0.5 1 0 0.5 1 0 0.5 1 0 0.5 1 Duty Cycle Duty Cycle Duty Cycle Duty Cycle Simulation results – Neuronal effects Adaptation Adaptation + refractory Adaptation + refractory + OFF response Linear 2 1 1 1 1
BOLD response amplitude and linearity to different stimulus OFF periods Amplitude Linearity 0 1.5 linear measured -2 1 Relative Amplitude (measured / linear) % Signal Change measured linear -4 0.5 -6 0 0 5 10 15 20 0 5 10 15 20 Stimulus OFF Duration (s) Stimulus OFF duration (s)
20% 20% 20% Amplitude: 50% ON Amplitude: 25% ON Amplitude: 75% ON 10% 10% 10% slope = 1.33 slope = 0.90 slope = 0.58 0 0 0 0 10% 20% 0 10% 20% 0 10% 20% Amplitude: Blocked Amplitude: Blocked Amplitude: Blocked BOLD response to different stimulus duty cycles
Nonlinearity of oxygen extraction, E(f) 1.4 1.2 Linear prediction 1 E(f) / E0 Actual change Linear prediction 0.8 Actual change 0.6 0.4 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 Flow Small flow decrease Small flow increase
t Estimate Neuronal Input from BOLD fMRI Contrast-reversing Checkerboard estimated neuronal input measured response 20 s 1 s 2 s 0.5 s stimulus duration R.M. Birn, et al. Proc ISMRM 2002
BOLD response to neuronal transients Stimulus Steady-state neurons a = initial slope BOLD Response amplitude Neurons responding to change b = final slope Stimulus Duration a Population response b
CR-Checkerboard vs. Static Grating 10 Contrast-Reversing Checkerboard 5 Amplitude (%) Static Grating 0 0 1 2 3 4 5 Stimulus Duration (s)
measured linear time (s) Different stimulus “OFF” periods R.M. Birn, et al. Proc. ISMRM, 2001. BOLD Response Signal Stimulus timing 2 s 3 s 4 s 8 s 16 s Brief stimulus OFF periods produce smaller decreases than expected
Varying “ON” and “OFF” periods R.M. Birn, et al. Proc. OHBM 2001. • Rapid event-related design with varying ISI 8% ON 25% ON 50% ON 75% ON
8% ON Measured Blocked Response 8% ON 25% ON 50% ON 25% ON Signal 50% ON 75% ON 75% ON Signal 0 10 20 30 40 0 5 15 10 time (s) time (s) Varying “ON” and “OFF” periods R.M. Birn, et al. Proc. OHBM 2001. Estimated Impulse Response Predicted Responses to 20 s stimulation