The blastoporal organiser of a sea anemone

amygdala. Both conditioned stimuli and emotional faces produce strong amygdala activation when presented unconsciously, emphasizing the importance of the amygdala as an implicit information processor and its role in unconscious memory. Findings regarding the human amygdala are mainly at the level of the whole region rather than nuclei (Figure 6). Structural and/or functional changes in the amygdala are associated with a wide variety of psychiatric conditions in humans. These include various anxiety disorders (PTSD, phobia and panic), depression, schizophrenia, and autism, to name a few. This does not mean that amygdala causes these disorders. It simply means that in people who have these disorders alterations occur in the amygdala. Because each of these disorders involves fear and anxiety to some extent, the involvement of the amygdala in some of these disorders may be related to the increased anxiety in these patients. Conclusion Not so long ago the amygdala was a neglected area of the brain, attracting much less scientific interest than other regions such as the neocortex, hippocampus, or cerebellum. In recent years, though, scientists have turned their attention to the amygdala, revealing its structural organization, physiological mechanisms, and functions, both in animals and humans. Recent studies have also implicated the amygdala in a variety of psychiatric disorders. In spite of this progress much remains unknown, especially about behavioral functions. However, the broad base of knowledge obtained in recent years provides a firm foundation upon which to build on in future work. Fear and anxiety: animal models and human cognitive psychophysiology. (1997). Organization of intra-amygdaloid circuitries in the rat: an emerging framework for understanding functions of the amygdala. In 1924 Hilde Mangold and Hans Spemann transplanted the dorsal blastopore lip of an amphibian embryo to a host embryo's ventral side. This experiment revealed that the dorsal blastopore lip can act as an 'organiser' to induce a secondary body axis [1]. The organiser experiment has fueled research in vertebrate developmental biology until today [2,3]. While an organiser might have been present in the chordate ancestor [4], it is not clear how widespread the principle of the blastoporal organiser is and what its evolutionary roots are. Here, we examined the organising activity of different parts of embryos of the sea anemone Nematostella vectensis, a representative of the basal animal phylum Cnidaria, which has retained many ancestral traits. We show by transplantation of small parts of the gastrula embryo that the blastopore lip …