Final answer:
A stereotactic instrument or frame is used to precisely position electrodes in the brain for neuroscience research or neurosurgical interventions.
Step-by-step explanation:
The apparatus that helps researchers precisely position electrodes into the brain is called a stereotactic instrument or frame. This technical equipment is essential for procedures that require accurate placement of electrodes, such as deep brain stimulation (DBS), during neuroscience research or neurosurgical interventions. The stereotactic instrument allows for precise targeting within the brain's three-dimensional space and is used in conjunction with various imaging techniques to guide the procedure.