Describe the procedures that are made possible by the use of stereotaxic surgery. Explain why this type of surgery provides more information than studying human cases or "nature's experiments."

Question

What will be an ideal response?

Answer 1

Stereotaxic surgery makes it possible for scientists to place an instrument at a precise location in the brain. Sometimes this is done to insert an electrode to record from or stimulate electrical activity in cells within a particular brain area. Electrodes can also be inserted to selectively damage a brain area, and later investigation can be done to determine the effects of that brain damage. Surgical instruments for ablation procedures can also be targeted to examine the effects of damaging a particular brain region. A cannula can be inserted into a specific brain area and then be used to deliver chemicals such as drugs or neurotransmitters to that particular region. Microdialysis can be performed, in which a cannula can be targeted to a specific brain area and chemicals can be taken up from that area for analysis. The brain can also be stimulated through optogenetic techniques, in which a stereotaxic instrument can be used to target specific brain cells for creation of light-sensitive channels. All of these approaches are more specific than "natural experiments" or human cases because the brain areas involved can be selectively targeted, and in "natural experiment," damage is rarely restricted to one brain area. In addition, these techniques allow for measurement of brain and behavior characteristics before any changes are made to the brain.