Midbrain Tectum Development

Midbrain Tectum Development

The “roof” or tectum of the midbrain contains paired anterior hillocks (the superior colliculi) and paired posterior hillocks (the inferior colliculi).  Joe Altman began his scientific career with an electrophysiological study of the superior colliculus after visual stimulation in cats.  He followed up those studies with anatomical investigations of the projections of the optic tract after lesions.

The following left figure is from Altman and Malis (1962), the right figure is from Altman (1962).

 


Many years later, Altman and Bayer studied the time of origin of neurons in the auditory and visual pathways as part of their comprehensive study of rat brain development.  The two papers appeared in 1981 in Experimental Brain Research, and emphasized development of the superior and inferior colliculi.  Each paper contains summary diagrams showing the relationships between neurogenetic gradients and anatomical topographic projections.  The figure below is a simplified diagram from the first paper showing how neurogenetic gradients and tonotopic order match in the inferior colliculus, medial geniculate body in the thalamus, and primary auditory cortex.


The following paper on development of the superior colliculus discusses the complex neurogenetic gradients that exist between the various layers of the superior colliculus.

 

 

File Download: