Biomedical Engineering Reference
In-Depth Information
Stimulation of two forepaws
a
SEP
b I
left only
R Paw Stim.
L Paw Stim
200
190
ISI
a
180
170
b
160
ISI
75 msec
0
50
100
150
200
200
ISI
0
msec
x
x
190
180
170
L Paw Stim
R Paw Stim
160
0
50
100
150
200
40 msec
200
40
msec
190
180
170
160
12.5 msec
0
50
100
150
200
200
75
msec
N1
190
180
170
I
I
0
50
100
150
200
Image Number
Fig. 11.1. (
a
) Somatosensory evoked potential (SEP) and (
b
) BOLD signal; two activation signals in a timecourse indicate
separate trials for verifying reproducibility. Single forepaw electrical stimulation (1 mA, 300 usec pulse, 1 Hz 4 s) in Rat.
Cross-hemisphere Interaction
1.5
1.0
0.5
0.0
-150
-100
-50
0
50
100
150
ISI msec
Detecting fast temporal phenomena by fMRI
Fig. 11.2. Cross-Hemisphere interaction. SEP and BOLD responses with the two-
forepaw stimulation. The symbols (
) are those of SEP measurements only, and filled
circle symbols are those of MRI measurements without EEG electrodes. Open square
symbols are SEP, and filled square symbols are BOLD respons. Paradigm I is flicker pat-
tern, flashed once. Paradigm II is a moving pattern in which two bars were jumped with
the speed of 4 degrees per 50 ms. Paradigm III is a repeated moving pattern of paradigm
II with 200-ms ISI. One event consisted of 4 repetitions with 1.5 s lap-time.
