DHA is known to significantly alter many basic properties of cell membranes including their 'fluidity', elastic compressibility, permeability, and interactions with key regulatory proteins. These various properties and mechanisms of action of DHA in the nervous system including its modulatory effect on the activity ion channels are thought to underlie its role in supporting electrical signaling and ultimately brain functioning such as learning ability, memory, etc. The high levels of DHA in the brain and nervous system are actively deposited particularly during the last trimester of pregnancy and during the first two months of infancy and very early years of a child's life. A source of DHA to brain and nervous tissues is needed to replenish and maintain optimal DHA levels for functioning throughout the lifespan. It is noteworthy that in direct contrast to DHA, EPA is found in near trace amounts in the brain as is ALA regardless of the amount of ALA consumed in the diet. There is some evidence that EPA, while not a significant structural component of brain tissue, may contribute to brain functioning in health and disease by effects such as increasing blood flow and influencing hormones and the immune system which can have overall effects on brain function.