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: The plasticity of primary motor cortex ( M1 ) in patients with Parkinson ' s disease ( PD ) and levodopa - induced dyskinesias ( LIDs ) is severely impaired .
### Output Text:
The plasticity of primary motor cortex ( M1 ) in patients with Parkinson ' s disease ( PD ) and <span class="chemical">levodopa</span> - induced dyskinesias ( LIDs ) is severely impaired . 