Researchers discovered that the limbic system in the human brain has its counterpart in the fish’s telencephalon. Both are involved in pain perception.
The limbic system in humans becomes active when we feel pain or fear. The limbic system is made up of the amygdala, which processes and filters emotions, and the hippocampus, which is involved in memory.
The limbic system equivalent was difficult for researchers to identify in fish. The human embryo develops so that it lies deep in the brain. However, in fish, the embryo develops so that it is on the surface instead.
HUMAN LIMBIC SYSTEM HIGHLY ACTIVE WHEN PEOPLE FEEL PAIN
"A Spanish research team¹ was even able to identify an area of the goldfish brain that appears to serve a function similar to the limbic system², the region of the human brain that becomes highly active when people experience fear or pain. As with mammals, these cerebral receptors in fish consist of a number of anatomical structures: incoming signals to the amygdala are processed by an emotional filter, while the hippocampus is for memory, but also plays a key role in spatial orientation."
FISH EQUIVALENT OF LIMBIC SYSTEM
FOUND ON OUTSIDE OF BRAIN
"Researchers have long searched in vain for these two regions - apparently because they were looking in the wrong place. It turns out that as a fish matures from an embryo to a full-grown adult, its brain architecture is turned inside out: While the human amygdala and hippocampus lie deep below the cerebral hemispheres of humans, the comparable structures of a fully developed fish are located directly on the surface of the endbrain³."