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: We visualize , for the first time , the profile of structural deficits in the human brain associated with chronic methamphetamine ( MA ) abuse .
### Output Text:
We visualize , for the first time , the profile of structural deficits in the human brain associated with chronic <span class="chemical">methamphetamine</span> ( <span class="chemical">MA</span> ) abuse . 