The THALAMODEL project: visiting Dr. Insausti

A couple of days ago, we went to Albacete to visit Dr. Ricardo Insausti, full professor in human anatomy and embryology at the University of Castilla - La Mancha (UCLM). Dr. Insausti is going to be an instrumental part of the THALAMODEL project. He is going to find the donors whose brains we will use to build our models; and then he is going to extract the brains and carry out their fixation with formalin.

Brain fixation is critical to study the brain ex vivo (meaning, outside a living body). If a brain sample is not fixated soon after death, it deteriorates quickly due to the blood supply. After the fixation, the brain can be preserved for a long time.

Dr. Insausti, holding a fixed human brain

 Dr. Insausti is also going to carry the histological study. Such study consists of two different phases: slicing the brain, and staining the slices. In order to slice the brain (or in our case, a block of tissue around the thalamus) into very thin sections, one first freezes the sample with dry ice and then sections it with a machine called "microtome". As opposed to thicker blocks of tissue, these thin slices can be examined under the microscope.

Rather than looking at the slices directly, one enriches their contrast first through a staining process. Different types of stains and dyes can be used to enhance different properties of the tissue. The most popular technique is arguably Nissl staining, invented by Franz Nissl in the late 19th century. After staining, the samples are mounted on slides that protect them, and can then be examined with a microscope.

Nissl-stained slice of human thalamus

Looking at mounted slides with samples of a human hippocampus

 Finally, Dr. Insausti will use the stained slices to manually trace the boundaries of the thalamic nuclei. This information will be critical for us to build the thalamic atlas which is at the core of our project. How we go from slices of the thalamus to a 3D atlas of the thalamic nuclei will be discussed in future posts.