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: Memory retrieval of experiences acquired prior to cocaine administration was impaired and negatively correlated with NFkappaB activity in the frontal cortex .
### Output Text:
Memory retrieval of experiences acquired prior to <span class="chemical">cocaine</span> administration was impaired and negatively correlated with NFkappaB activity in the frontal cortex . 