 A second hypothesis has been generated based on data that suggest GAL is involved in protecting the hippocampus from excitotoxic damage and the neurons in the cholinergic basal forebrain from amyloid toxicity.Galanin participates in cognitive performance and has been shown to weaken learning and cognition.Noradrenaline and serotonin, two neurotransmitters involved in depression, are both co-expressed and modulated by galanin, suggesting that galanin plays a role in the regulation of depression.