 In this video I will identify the major structures of the brain and describe their functions and I will describe the structure and function of the five lobes of the cerebral cortex. In this image of the human brain we can see there are numerous folds on the surface of the brain. The large region of the brain responsible for conscious perception, higher cognitive functions like language and voluntary control over movement is this cerebrum in the grey matter we can see in the outermost layer of the cerebrum is the cerebral cortex. This grey matter contains neurons that are organized into six layers and then deep to the cerebral cortex is white matter of the cerebrum that contains axons connecting one region of the brain to another region of the brain. In this illustration we see a comparison of the cerebral cortex in humans to other mammals like cats, rats, chimpanzees and dolphins. You'll notice that the cerebral cortex of the human and dolphin brains are very wrinkly with a large surface area folded into numerous gyri. In contrast the rat and cat brain are relatively smooth because they have a much smaller surface area of cerebral cortex. The cerebral cortex contains the control centers that are responsible for carrying out many of our higher cognitive functions. Through human evolution the cerebral cortex has greatly expanded to enable us to have a wider range of functional capacities. We can see that the chimpanzee our closest relative here has a less wrinkled brain than the human brain. We can also see that the dolphin has a very large cerebral cortex and it's thought that this is because they have a very complex environment. They are navigating a complex social world and they have a very complex behavior similar to humans. We have a complex repertoire of behaviors and we navigate this complex social world that requires us to have a large amount of cerebral cortex surface area. While the cerebral cortex is the most superficial layer of grey matter in the cerebrum, deep to the cerebral cortex is the white matter of the cerebrum. The corpus callosum is a large tract of white matter that connects the left cerebral hemisphere and the right cerebral hemisphere. Deep to the white matter of the cerebrum are the basal nuclei. The striatum and globus pallidus are basal nuclei that are involved in processing commands and regulating motivation. Deep to the cerebrum is a region of the brain known as the diencephalon. The diencephalon includes the thalamus and the hypothalamus. A major function of the thalamus is to relay sensory information to the cerebral cortex. A major function of the hypothalamus is to control the autonomic nervous system and the endocrine system. We can see the pituitary gland is located just inferior to the hypothalamus and the hypothalamus will control the secretion of hormones from the pituitary gland. The brainstem is located just inferior to the diencephalon and there are three major regions of the brainstem, the midbrain, the pons and the medulla oblongata. The midbrain is the most superior region of the brainstem. The midbrain contains tracts of white matter that relay information to the diencephalon and cerebrum from the more inferior regions of the central nervous system. The midbrain also contains nuclei that function as control centers for simple reflexes. The pons is the middle region of the brainstem and the pons contains important control centers that are involved in regulating the respiratory drive to regulate breathing. The pons also connects to another region of the brain known as the cerebellum and will be involved in regulating involuntary control over motor commands. Inferior to the pons, the medulla oblongata connects the brain to the spinal cord and the medulla oblongata contains several important control centers that regulate vital reflexes. For example, the medulla oblongata contains a cardiovascular control center that's involved in regulating the heart. The medulla oblongata also contains a respiratory control center that, together with the nuclei of the pons, regulate the respiratory drive to control breathing. There's also a deglutition center that's regulating swallowing and there's a control center in the medulla oblongata responsible for coordinating vomiting as a reflex. Similarly, coughing is another reflex coordinated by a control center in the medulla oblongata. The cerebellum is a region of the brain located just posterior to the brainstem. The cerebellum has an extremely folded surface with numerous small ridges known as folia. The cerebellum contains an extraordinarily high density of neurons, although the volume of the cerebellum is approximately 10% of the volume of the brain, the cerebellum does contain the majority of neurons in the brain. The functions of the cerebellum include involuntary unconscious coordination of motor commands. These functions are important for maintaining posture and balance, but are also important for fine-tuning skilled movements. The cerebellum is involved in a type of learning that will store error signals from past motor commands and use those to fine-tune and correct motor commands that will make in the future. Here we see an illustration of the major lobes of the cerebral cortex. In each hemisphere of the cerebrum there are 5 lobes of the cerebral cortex and 4 out of 5 can be seen from the surface and are shown in this illustration. The frontal lobe is the most anterior of the lobes of the cerebrum. A major function of the frontal lobe is the control of motor commands. The precentral gyrus is a region of the frontal lobe that contains primary motor cortex where the neurons in the precentral gyrus will send commands to our skeletal muscles to stimulate contraction as a way of regulating the brain. The precentral gyrus is named precentral because it is just anterior to the central sulcus. The central sulcus divides the frontal lobe from the parietal lobe. The parietal lobe is shown in the purple color in the illustration here. The parietal lobe is just posterior to the frontal lobe on the superior region of the cerebrum. A major function of the parietal lobe is processing somatosensory information, that is, sensory information that is coming from the skin, commonly known as touch. The postcentral gyrus is the location of primary somatosensory cortex, the first region of the cerebral cortex that is involved in processing sensory information coming from the somatosensory receptors of the skin. The most posterior region of the cerebral cortex, shown in the green color in the illustration here, is known as the occipital lobe. One of the major functions of the occipital lobe is processing visual information. Primary visual cortex is found in the occipital lobe, and that is the first region of the cerebral cortex that is involved in processing visual information coming from the eyes. The temporal lobes are shown in blue in the illustration here. The temporal lobes are found just inferior to the frontal and parietal lobes. The lateral sulcus separates the temporal lobes from the frontal and parietal lobes. The temporal lobes are important for processing auditory sensory information, as well as olfactory sensory information. The auditory is hearing and olfactory is the sense of smell. The temporal lobe is also important for processing and storing memories and emotions. Here we have a view of the brain that has been sliced through the coronal plane. So this is a coronal section of the brain that will allow us to see deep to the frontal and temporal lobes. The region of the cerebrum known as the insula or the insular lobe of the cerebral cortex. The functions of the insular lobe include processes important for emotions, as well as the processing of the sense of taste, also known as gustation. Much of our understanding of the functions of the brain have come from damage to the brain. A hemorrhagic stroke is damage to blood vessels in the brain that causes bleeding in the brain that will destroy neurons and disrupt functions that were being carried out by the cells in that region of the brain. And so by studying patients that have had damage to the brain, such as a stroke, we can see what functions have been lost and infer that the regions of the brain that were damaged were somehow involved in those functions. Studying patients that had developed language impairments following damage to the brain has led to the classic model of the language network. These patients tended to have damage in the left hemisphere of the cerebral cortex. In two specific regions of the brain, a region of the left temporal lobe, now known as Wernicke's area, was associated with impairments of language comprehension. Patients that had damage in a region of the left frontal lobe, now known as Broca's area, had impairments in speech production. This has led to an understanding of the language network in the brain, which is usually found in the left hemisphere, and involves a general interpretation area of the brain, including Wernicke's area in the left temporal lobe, and a speech production area located in the left frontal lobe, including Broca's area. Further evidence that the language network is located in the left hemisphere of the cerebrum comes from experiments with split brain patients that have had the corpus callosum severed, disconnecting the left hemisphere of the cerebrum from the right hemisphere of the cerebrum. In these experiments, patients are shown a visual stimulus on a screen, and that stimulus is displayed into just one half of their visual field. Information displayed in the right half of the visual field will be processed by the left half of the brain, and information displayed in the left half of the visual field will be processed by the right half of the brain. When patients are shown an image in the right half of the visual field, a split brain patient is able to verbally identify what they see. However, when a split brain patient is shown an image in the left half of the visual field, they report that they see nothing. However, then, if they are asked to use their left hand to draw what they've seen, they're able to correctly draw a representation of the image that they were shown. This demonstrates that it is the left hemisphere of the brain that's responsible for producing verbal language, and the right hemisphere of the brain which is processing the left half of the visual field is not able to send out information through verbal language, but is still able to communicate by controlling the left hand. Another approach for learning about the functions of the brain is functional imaging. Functional magnetic resonance imaging is a technique that measures increases in blood flow in regions of the brain that are associated with increased signaling. This image is taken from a patient that's observing a visual stimulus, and we can see increased blood flow to regions of the visual sensory pathway in the thalamus and the occipital lobe.