AB 19:97-109 (2013)  -  DOI: https://doi.org/10.3354/ab00525

FEATURE ARTICLE
Distribution of glutamic acid decarboxylase immunoreactivity within the brain of oval squid Sepioteuthis lessoniana 

Shiori Kobayashi1, Chitoshi Takayama2, Yuzuru Ikeda1,*

1Department of Marine and Environmental Sciences, Graduate School of Engineering and Science, and 2Department of Molecular Anatomy, Graduate School of Medicine, University of the Ryukyus, Okinawa 903-0213, Japan
*Corresponding author. Email:

ABSTRACT: Coleoid cephalopods (squid, cuttlefish, and octopus) have the largest and most complex brains of all invertebrates and show behavioral abilities similar to those of vertebrates. Among the coleoids, the oval squid Sepioteuthis lessoniana forms well-structured schools that are indicative of sociality. These behaviors are reflected in aspects of the well-developed brain. In this study, we focused on the role of the cephalopod brain in complex behavior. In order to reveal the network of γ-aminobutyric acid (GABA) in coleoids, we examined the immunohistochemical localization of glutamic acid decarboxylase (GAD), which is the synthetic enzyme of GABA, in the brain of young S. lessoniana. We found that GABAergic neurons and their axons were distributed throughout the brain. GABA neurons were abundantly localized in the inferior frontal lobe, which is involved in controlling arm motions, and in the subesophageal masses, which are lower and intermediate centers of action. GABAergic fibers were abundantly localized in the tract that runs from the superior frontal lobe to the vertical lobe. These results suggested the involvement of GABA in both cognitive behaviors (such as learning and memory) and in movement.


KEY WORDS: Glutamic acid decarboxylase · Neurotransmitter · Brain · Oval squid · GABA · γ‑aminobutyric acid


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Cite this article as: Kobayashi S, Takayama C, Ikeda Y (2013) Distribution of glutamic acid decarboxylase immunoreactivity within the brain of oval squid Sepioteuthis lessoniana . Aquat Biol 19:97-109. https://doi.org/10.3354/ab00525

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