Figure 2From: Learning in a simple biological system: a pilot study of classical conditioning of human macrophages in vitroIL-6 secretion over successive pairings. Macrophage cultures from group 2, having received UCS at pairing and control medium at evocation, were kept in culture for an additional 10 days, undergoing pairing every second day. Solid lines represent means of IL-6 levels ± standard errors, while dashed lines represent IL-6 levels of individual cell cultures. IL-6 was measured after each UCS stimulation, and habituation was seen from the fourth pairing and onwards.Back to article page