flashbulb memories. These are instances in which memories of powerful emotional events are more highly detailed and enduring than regular memories (e.g. September 11 attacks, assassination of JFK). These memories have been linked to increased activation in the amygdala. Recent studies of patients with damage to the amygdala suggest that it is involved in memory for general knowledge, and not for specific information. Other structures involved The regions of the diencephalon have shown brain activation when a remote memory is being recovered and the occipital lobe, ventral temporal lobe, and fusiform gyrus all play a role in memory formation. Lesion studies Lesion studies are commonly used in cognitive neuroscience research. Lesions can occur naturally through trauma or disease, or they can be surgically induced by researchers. In the study of declarative memory, the hippocampus and the amygdala are two structures frequently examined using this technique. Hippocampal lesion studies The Morris water navigation task tests spatial learning in rats. In this test rats learn to escape from a pool by swimming toward a platform submerged just below the surface of the water. Visual cues that surround the pool (e.g. a chair or window) help the rat to locate the platform on subsequent trials. The rats' use of specific events, cues, and places are all forms of declarative memory. Two groups of rats are observed: a control group with no lesions and an experimental group with hippocampal lesions. In this task created by Morris, rats are placed in the pool at the same position for 12 trials. Each trial is timed and the path taken by the rats is recorded. Rats with hippocampal lesions successfully learn to find the platform. If the starting point is moved, the rats with hippocampal lesions typically fail to locate the platform. The control rats, however, are able to find the platform using the cues acquired during the learning trials. This demonstrates the involvement of the hippocampus in declarative memory. The Odor-odor Recognition Task, devised by Bunsey and Eichenbaum, involves a social encounter between two rats (a subject and a demonstrator). The demonstrator, after eating a specific type of food, interacts with the subject rat, who then smells the food odor on the other's breath. The experimenters then present the subject rat with a decision between two food options; the food previously eaten by the demonstrator, and a novel food. The researchers found that when there was