to the development of a homunculus for the motor and sensory cortices, which is a diagram showing the brain's connections to different areas of the body. An example is the cortical homunculus of the primary motor cortex and the somatosensory cortex, which are separated by the central sulcus. The diagram starts in the longitudinal fissure and continues out laterally from the center of the brain, representing the general pattern from lower extremities and genitals in the fissure up to the hands and face on outer edges of the brain. Motor Mapping Functional testing of movement during cortical stimulation includes looking for active movement and inhibition of movement. When the precentral gyrus of the frontal lobe is stimulated, specific muscles in the body will contract based on the location of the brain that receives the electric signal. Stimulation on one side of the brain will cause a contraction on the contralateral, or opposite, side of the body. More recent studies using CSM have shown that the motor cortex is more complex than the arrangement pictured traditional homunculus, and that motor responses occur in the frontal lobe further away from the narrow strip next to the central sulcus. Areas of the cortex that inhibit movement upon stimulation have been found in some cases to be supplemental and not vital to motor function. These areas have been removed without compromising a patient's ability to move post-operation. Language Mapping During stimulation various language tasks are used to check brain function such as reading sentences, auditory comprehension, and spontaneous speech such as naming objects. Cortical stimulation in language areas of the brain typically tests for the inhibition of some language capability, rather than a defined motor or sensory response. This can make language mapping require more complex language-related tasks to be assessed during testing, in order to determine if the site that is stimulated is essential to a certain language ability. Language mapping is normally done in the left hemisphere of the brain where most language areas are located, such as Broca's and Wernicke's areas. Cortical stimulation mapping has also identified a language area in the basal temporal cortex that was previously unknown. Cortical stimulation mapping in patients with epilepsy has shown that critical language areas of the brain vary greatly in patients, highlighting the need to perform accurate mapping prior to surgeries in language areas. Traditional landmarks such as Broca's and Wernicke's areas cannot