Figure 6.

The rate of change in the real (a) and imaginary (b) parts of brain impedance after hemorrhagic and ischemic stroke in the low (10 Hz–1 kHz; reference frequency: 10 Hz), intermediate (1–100 kHz; reference frequency: 1 kHz) and high frequency (100 kHz–1 MHz; reference frequency: 100 kHz) ranges, as obtained from $\Delta \mathit{Z}=\Delta {\mathit{Z}}_{\mathit{r}\mathit{e}\mathit{a}\mathit{l}}+\mathit{j}\Delta {\mathit{Z}}_{\mathit{i}\mathit{m}\mathit{a}\mathit{g}}={\mathit{Z}}_{\mathit{a}\mathit{f}\mathit{t}\mathit{e}\mathit{r}}-{\mathit{Z}}_{\mathit{b}\mathit{e}\mathit{f}\mathit{o}\mathit{r}\mathit{e}}$, where ${\mathit{Z}}_{\mathit{b}\mathit{e}\mathit{f}\mathit{o}\mathit{r}\mathit{e}}$ and ${\mathit{Z}}_{\mathit{a}\mathit{f}\mathit{t}\mathit{e}\mathit{r}}$ represent brain electrical impedance before and after stroke, respectively.