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. Author manuscript; available in PMC: 2009 Jan 1.
Published in final edited form as: Neurosci Biobehav Rev. 2007 May 18;32(1):20–39. doi: 10.1016/j.neubiorev.2007.04.019

Figure 1.

Figure 1

Meal analysis of two representative rats living in operant chambers. The one maintained on Daily Intermittent Sucrose and Chow (black lines) had an increased intake of sugar compared with one given Ad libitum Sucrose and Chow (grey lines). Hour 0 is 4 h into the dark phase. Each lever press delivers 0.1 mL of 10% sucrose. A sugar meal is defined as ending when the rat does not press for 2 min. Both rats consume several meals of about equal size on day 1 (top panel). Note that the rat with sugar available 24 h also drinks during the inactive (light) phase. By day 21 (bottom panel), the rat with sucrose and chow available for only 12 h consumes an initial “binge” of sucrose (indicated by the first arrow), followed by fewer, but larger meals, than the rat with sucrose and chow ad libitum. Sugar-bingeing rats are the ones that show signs of dependency in a battery of tests.