Amygdala

Character History
Anatomically, the amygdala refers to the bundle of nerve cells in the brain that control emotional associations of many kinds. Helzinger's amygdala cluster was removed in an attempt to cure him of his homicidal rage (apparently by a doctor who did not understand the difference between the amygdala and the hypothalamus). This procedure resulted in Amygdala becoming exceedingly angry and was the opposite of what the surgery was supposed to achieve. Easily led due to his childlike nature, Amygdala has been the pawn of a number of Batman villains, but when properly medicated, he can be peaceful.

Amygdala first appeared in Shadow of the Bat #3 in 1992 during the story arc of the four-parter Batman: The Last Arkham which began the new line of comics. In the issue, Amygdala was forced to attack Batman by the maddened Jeremiah Arkham. Batman subdued Amygdala, but was then forced to face more inmates.

Amygdala later appeared in Part 2 of the year-long story arc Batman: Knightfall, which also saw other characters introduced in Batman: The Last Arkham return to the comic book universe, most notably Zsasz and Jeremiah Arkham. In Knightfall, Amygdala was freed from Arkham Asylum by Bane along with numerous other inmates and was soon under the control of The Ventriloquist. Batman intercepted Ventriloquist, but was promptly attacked by Amygdala. As Ventriloquist escaped, Batman subdued Amygdala once more and the villain no longer took part in Knightfall.

He has been released into the community on numerous occasions, where he has been an ally and friend of Dick Grayson (Nightwing, the former Robin); He lived in the hero's apartment building and worked as a warden in Lockhaven Prison. When Blockbuster was in the process of breaking Nightwing down both physically and emotionally, he blew up Grayson's apartment complex with Amygdala inside. Amygdala survived, but was heavily traumatized by the death of his friends.

Powers and Abilities
Amygdala has enhanced strength and endurance.

In other media
In the animated series Justice League Unlimited, Amygdala was seen at Roulette's Meta-Brawl.

In the Elseworlds tale, Batman: Crimson Mist, Amygdala makes a cameo during the vampire Batman's assault on Arkham Asylum. He is killed and then beheaded by the vampire Batman.