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: Electrophysiological recordings showed that microinjection of neurotensin induced excitation of pallidal neurons in the presence of systemic haloperidol administration .
### Output Text:
Electrophysiological recordings showed that microinjection of <span class="chemical">neurotensin</span> induced excitation of pallidal neurons in the presence of systemic <span class="chemical">haloperidol</span> administration . 