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: This study focuses on behavioral syndromes that may used as models for Parkinson ' s disease , or tardive dyskinesia , and its response after glutamatergic blockage .
### Output Text:
This study focuses on behavioral syndromes that may used as models for Parkinson ' s disease , or tardive dyskinesia , and its response after glutamatergic blockage . 