In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Morphological analysis of frontal forebrain sections with light microscopy revealed seizure - related damage to the hippocampal formation , thalamus , amygdala , olfactory cortex , substantia nigra and neocortex , which is typically observed with pilocarpine in doses exceeding 350 mg / kg .
### Output Text:
Morphological analysis of frontal forebrain sections with light microscopy revealed seizure - related damage to the hippocampal formation , thalamus , amygdala , olfactory cortex , substantia nigra and neocortex , which is typically observed with <span class="chemical">pilocarpine</span> in doses exceeding 350 mg / kg . 