It is an excellent example of the way that the various regions of the brain are highly specialized. Interestingly, each of our various body parts has a unique portion of the primary motor cortex devoted to it.
Each individual finger has about as much dedicated brain space as your entire leg. Your lips, in turn, require about as much dedicated brain processing as all of your fingers and your hand combined! Figure 5. Spatial relationships in the body are mirrored in the organization of the somatosensory cortex. Because the cerebral cortex in general, and the frontal lobe in particular, are associated with such sophisticated functions as planning and being self-aware they are often thought of as a higher, less primal portion of the brain.
Indeed, other animals such as rats and kangaroos while they do have frontal regions of their brain do not have the same level of development in the cerebral cortices.
The closer an animal is to humans on the evolutionary tree—think chimpanzees and gorillas, the more developed is this portion of their brain. It contains the somatosensory cortex , which is essential for processing sensory information from across the body, such as touch, temperature, and pain. The somatosensory cortex is organized topographically, which means that spatial relationships that exist in the body are generally maintained on the surface of the somatosensory cortex.
For example, the portion of the cortex that processes sensory information from the hand is adjacent to the portion that processes information from the wrist. Figure 6. The types of deficits are very different, however, depending on which area is affected. The auditory cortex , the main area responsible for processing auditory information, is located within the temporal lobe. The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information.
You will learn much more about how visual information is processed in the occipital lobe when you study sensation and perception. Consider the following advice from Joseph LeDoux, a professor of neuroscience and psychology at New York University, as you learn about the specific parts of the brain:. Be suspicious of any statement that says a brain area is a center responsible for some function. The cerebrum is divided into two hemispheres — the right hemisphere and the left hemisphere.
Bridging the two hemispheres is a bundle of fibers called the corpus callosum. The two hemispheres communicate with one another across the corpus callosum. Covering the outermost layer of the cerebrum is a sheet of tissue called the cerebral cortex. Because of its gray color, the cerebral cortex is often referred to as gray matter.
The wrinkled appearance of the human brain also can be attributed to characteristics of the cerebral cortex. More than two-thirds of this layer is folded into grooves. The function of the cerebral cortex can be understood by dividing it somewhat arbitrarily into zones, much like the geographical arrangement of continents. The frontal lobe is responsible for initiating and coordinating motor movements; higher cognitive skills, such as problem solving, thinking, planning, and organizing; and for many aspects of personality and emotional makeup.
The parietal lobe is involved with sensory processes, attention, and language. Damage to the right side of the parietal lobe can result in difficulty navigating spaces, even familiar ones. The temporal lobe helps process auditory information and integrate information from the other senses. Neuroscientists also believe that the temporal lobe has a role to play in short-term memory through its hippocampal formation, and in learned emotional responses through its amygdala.
All of these structures make up the forebrain. Other key parts of the forebrain include the basal ganglia, which are cerebral nuclei deep in the cerebral cortex; the thalamus; and the hypothalamus. These neighboring areas are mostly buried within the lateral sulcus as well, but may extend out to the superior temporal gyrus. The demarcations of the auditory cortex in general, however, are imprecise. The auditory cortex plays a critical role in our ability to perceive sound. It is thought to be integral to our perception of the fundamental aspects of an auditory stimulus, like the pitch of the sound.
But it is also important in various other aspects of sound processing, like determining where in space a sound originates from as well as identifying what might be producing the sound. The auditory cortex is also thought to be involved in higher-level auditory processing, such as recognizing aspects of sound that are specific to speech.
Damage to the auditory cortex can disrupt various facets of auditory perception. For example, damage e. The auditory cortex primarily receives auditory information from a nucleus in the thalamus called the medial geniculate nucleus , which is where all incoming information about hearing is sent before it is processed by the cerebral cortex.
Cells in the primary region of the auditory cortex and in some parts of the non-primary regions as well are arranged so they form what is known as a tonotopic map. What this means is that different areas of the auditory cortex are involved in processing different sound frequencies. Frequency , when referring to sound waves, is related to pitch.
High frequency sound waves lead to high-pitched sounds. The tonotopic arrangement of the primary auditory cortex is similar to what is seen in the cochlea , where sound processing begins. Thus, it can be said that the core of the auditory cortex contains a map of the cochlea, with each point in the cochlea corresponding to a strip of cells in the auditory cortex.
This type of arrangement is similar to what is seen in other sensory cortices e.
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