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. 2019 Jul 7;40(6):1274–1289. doi: 10.1177/0271678X19861604

Figure 1.

Figure 1.

(a) Shows the experimental set-up. An open cranial window was implanted in the area of the cerebellar foliae V and VIa.85 The subdural DC/AC-ECoG was recorded with an Ag/AgCl electrode, the intracerebellar DC/AC-ECoG and [K+]o with a K+-sensitive microelectrode and rCBF as well as IOS with a laser-Dopper flow probe (LDF). (b) Gives the full experiment 1 in which the increase of [K+]ACSF from 3 to 250 mM for 1 h induced a long-lasting depolarizing event superimposed with 34 SDs. In response to the increase in [K+]ACSF, the intracerebellar DC potential showed a negative drift with incomplete recovery after washout, whereas the subdural DC potential displayed a positive drift followed by a negative drift after washout. The positive DC drift at the subdural Ag/AgCl electrode was an electrochemical artefact due to the decrease in [Cl−]ACSF which we replaced with acetate. The superimposed SDs were characterized by a transient negative DC shift at both the intracerebellar and the subdural electrode as well as increases in [K+]o, IOS and rCBF. Note that SD-induced depression of spontaneous activity was not visible. (c) Two of 23 SDs of a cluster under [K+]ACSF at 250 mM are shown (taken from experiment 2). Similar to experiment 1, the SDs are characterized by a negative DC shift at both electrodes and transient increases in rCBF and IOS. Negative DC shifts and IOS change started at different time points indicating that the SDs propagated in the tissue. In contrast to experiment 1, [K+]o did not show significant increases during the SDs in experiment 2. This difference was most likely due to different positions of the electrode tips between different experiments in relationship to the cerebellar cortex layers and the white matter. Similar to experiment 1, SD-induced depression of activity was not seen in experiment 2, either. Note that the IOS increase corresponds with the negative DC shift rather than with the rCBF signal, indicating that it reflects changes in optical features of the parenchyma rather than changes of the cerebellar blood volume.

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