Learned taste aversion induced by cortical spreading depression

Male albino rats were cannulated and placed on a 24 hr water deprivation schedule. The animals were allowed 10 min access to water in a large animal cage for 5 days. On the sixth day of deprivation the animals were randomly divided into 6 groups and given either 12 percent KCl, 25 percent KCl, or Ringers solution applied unilaterally or bilaterally to the cortex immediately after access to 8 percent sucrose. On the seventh day of deprivation, each rat was placed in a two-choice situation with the sucrose solution and water. Only the unilateral and bilateral 12 percent KCl groups developed an aversion to the sucrose. These results indicate that CSD has aversive as well as amnesic properties, there exists a gradient of amnesia, dependent on concentration, and that the cortex is not necessary for learning a taste aversion.