Fezf2-positive fork cell-like neurons in the mouse insular cortex.

Area of Science:

• Neuroscience
• Cell Biology
• Comparative Anatomy

Background:

• Fork cells and von Economo neurons are distinctive neuronal types found in the insular and anterior cingulate cortices of higher animals, including humans and great apes.
• These neurons possess unique morphologies (non-pyramidal, bipolar/spindle-shaped) and are implicated in higher brain functions.
• Their presence in evolved species suggests specialized roles, but investigation in experimental animals is limited.

Purpose of the Study:

• To investigate the existence of neurons equivalent to human fork cells and von Economo neurons in the mouse insular cortex.
• To examine the morphology and molecular characteristics of Fezf2-positive neurons in mice, as Fezf2 is highly expressed in these distinctive human neurons.

Main Methods:

• Detailed morphological analysis of Fezf2-positive neurons in the mouse insular cortex.
• Electron microscopy to examine neuronal ultrastructure and cell interactions.
• Immunohistochemical analysis to detect the localization of specific molecules (neuromedin B, gastrin releasing peptide).

Main Results:

• While von Economo-like neurons were not identified, Fezf2-positive neurons with a fork cell-like morphology (two apical dendrites) were discovered in the mouse insular cortex.
• Electron microscopy revealed these neurons interact with other cells, termed 'holding neurons', rather than embracing capillaries.
• Key molecules like neuromedin B and gastrin releasing peptide, found in human fork/von Economo cells, were also localized in these mouse insular neurons.

Conclusions:

• The study identified Fezf2-positive neurons in the mouse insular cortex that share morphological and molecular similarities with human fork cells.
• These findings suggest the presence of a functional equivalent of the fork cell in mice, providing a model for studying these specialized neurons.
• This discovery facilitates further experimental investigation into the roles of these unique neurons in higher brain functions.