An in vitro model to study brain tissue recovery

Brain tissue slices can be maintained within metabolically stable conditions for long periods of time (hours). This experimental setting has been productive for investigating long-term neural function in vitro. Here, we utilize this experimental approach to describe the recovery of functional connectivity in slices from the mouse hippocampus. Hippocampal slices were cut up bisecting the CA1 region (parietal cut) and each severed half placed adjacent to the other. Stimulation and recording electrodes were placed on each side of the cut; with one electrode stimulating one hemi-slice (20 V, 0.033 Hz) and the other electrode recording the evoked response from the adjacent hemi-slice. As expected, no evoked response was observed shortly after the beginning of stimulation. However, 20-40 min after the initiation of stimulation a large depolarization signal was detected. Right after that, fiber volley potentials were observed in the adjacent hemi-slice. After 1 h excitatory postsynaptic potentials (EPSP) were detected. Based on this observation, we hypothesize that recovery of functional connectivity is enhanced by constant delivery of electrical pulses at low frequency to the damaged neural tissue. The described in vitro slice system may become a very suitable experimental method to investigate strategies to enhance the recovery of neural connectivity after brain injury.