you said that you prepared brain slices, but what exactly are they?

Question: you said that you prepared brain slices, but what exactly are they?
- Keywords:
  brain,
  slice
Asked by fatlouietwin to Simon on 14 Jun 2011. This question was also asked by fatlouie21, gail07.
- Simon Bennett answered on 14 Jun 2011:
  
  Hello,
  
  I cut out the hippocampus from the rats brains and then use a machine to cut them into very thin slices (400 micrometer or 0.4 of mm) so that I can get to the cells using my fine glass electrode.
  
  Let me know if you want any more information.
  
  Thanks.

Question: you said that you prepared brain slices, but what exactly are they?