Laboratory
2
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| Introduction |
In this laboratory, you will continue your inspection and identification of the brain's external landmarks. Before you start removing the meninges, review the arteries and nerve roots that you discovered in the last session since some of these landmarks may be lost. At the end of the session, remember to return the brain and all stray pieces of tissue to the bag to insure proper disposal at the end of the course. Be sure that the brain is covered with water while being stored in the bucket. During this laboratory session, you will focus your attention on identification of cortical gyri and sulci. The discussion will go beyond simple identification since we will begin to relate structure with function. Strange as it may seem, linking the structural heterogeneity of the brain with localization of function was a foregin concept prior to the nineteenth century. While we may now laugh at the prinicples of phrenology that were popularized by Sir Francis Gall and his student Johann Spurzheim, they highlighted two ideas that are still important today: one, we can associate specific functions with different parts of the brain; and two, enhanced use of specific neural functions can lead to enhanced synpatic connectivity and complexity in those areas of the brain that serve that function. This so-called plasticity can be reflected in increased volume and convolution of the the specific cortical areas we are looking at in this exercise (that's one reason why no two brains will ever look the same!). To illustrate the point, once you have removed the meninges (and figured out where the lateral fissue and insular cortex are located!), gently insert your index fingers into the left and right lateral fissures until they touch the insular cortex. You will probably find that you can insert your finger further on one side that the other - why? Nevertheless, we must never make the mistake of the phrenologists and attempt to make simplistic correlations between structure and function. Modern anatomical, physiological and functional imaging studies clearly indicate that function is the product of multiple systems in the brain working in concert to interpret and respond to physical and mental stimuli. The images on the following pages are designed to help you find your bearings when trying to identify specific structures and are not meant to exhaust what you may be able to discover on your specimens. Carefully follow the lab manual to make sure you find everything you need to in this laboratory session. |
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