Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Timeline of experimental phases. Monkeys received daily injections of saline (open boxes; Phases A and D) or morphine (filled box; Phases B and C). Values shown in the lower row are the minimum number of sessions for each phase. The entire timeline was repeated for each treatment condition (i.e., dose of morphine). Other details (daily treatment doses, order of conditions, and exact treatment durations) are provided in Table 1.
