Endocrine System and Brain Functions Overview

Endocrine System Another part of human biology relevant to psychology is the endocrine system. This is a system of glands that secrete hormones that affect many different biological processes in our bodies. The endocrine system is controlled in the brain by the hypothalamus (discussed more below). The endocrine system is complex, but a few elements of the entire process are especially relevant to psychologists. Table 4.2 includes the basic functions of some of humans’ important hormones. Table 4.2 Basic Functions of Important Hormones in Humans Hormone Adrenaline Leptin Ghrelin Melatonin Function Activated during the fight-or-flight response in stressful situations. Speeds up bodily processes. Involved in weight regulation. Suppresses hunger (food may be perceived as less appetizing). Motivates eating/increases hunger (food may be perceived as more appetizing). Triggers sleep and wakefulness responses in the brain. Oxytocin Promotes good feelings such as trust and bonding. Adrenal Glands The adrenal glands produce adrenaline (also known as epinephrine), which signals the rest of the body to prepare for fight or flight. This response was mentioned earlier in connection with the autonomic nervous system—the part of our nervous system that controls involuntary responses, such as heart rate and blood pressure. Ovaries and Testes Ovaries and testes produce our sex hormones, estrogen for females and testosterone for males. Research shows that levels of these hormones may partially explain gender differences demonstrated in certain experiments and situations. The Brain Possibly the most relevant part of biology to psychologists is the brain. As far as we can tell, the brain controls most of human thought and behavior. Researchers know quite a bit about brain anatomy and function, but many mysteries remain about how the brain functions. Studying how the brain works is challenging because we cannot simply observe brain function the way we might observe a heart beating. To our eyes, a brain thinking looks exactly like a brain not thinking. Researchers are discovering many new details about how the brain works by using experimentation and technology. However, we still have a long way to go before we really understand how the brain controls our thoughts and behavior. Ways of Studying the Brain As mentioned previously, the first challenge of brain research is creating a way of detecting brain function. The following describes some of the methods researchers use. Accidents In 1848, a railroad worker named Phineas Gage was involved in an accident that damaged the front part of his brain. Gage’s doctor took notes documenting the brain damage and how Gage’s behavior and personality changed after the accident. Accidents like this give researchers clues about brain function. Gage became highly emotional and impulsive after the accident. Researchers concluded that the parts of the brain damaged in the accident are somehow involved in emotional control. Phineas Gage Lesions Lesioning is the removal or destruction of part of the brain. This, of course, is never done purely for experimental purposes. Sometimes doctors decide that the best treatment for a certain condition involves surgery that will destroy or incapacitate part of the brain. For example, a person may develop a brain tumor that cannot be removed without removing part of the surrounding brain. When these types of surgeries are performed, doctors closely monitor the patient’s subsequent behavior for changes. Any time brain tissue is removed (lesioning), researchers can examine behavior changes and try to infer the function of that part of the brain. A famous historical example of lesioning is the frontal lobotomy. In the past, this surgery was used (many historians say overused) to control mentally ill patients who had no other treatment options. Researchers knew that lesioning part of the frontal lobe would make the patients calm and relieve some serious symptoms. Drug treatments have now replaced frontal lobotomies. Electroencephalogram An electroencephalogram (EEG) detects brain waves. Researchers can examine what type of waves the brain produces during different stages of consciousness and use this information to generalize about brain function. The EEG is widely used in sleep research to identify the different stages of sleep and dreaming. Computerized Axial Tomography A computerized axial tomography (CAT or CT) scan is a sophisticated X ray. The CAT scan uses several X ray cameras that rotate around the brain and combine all the pictures into a detailed three-dimensional picture of the brain’s structure. Note that the CAT scan can show only the structure of the brain, not the functions or the activity of different brain structures. A doctor could use a CAT scan to look for a tumor in the brain but would not get any information about how active different parts of the brain are. Magnetic Resonance Imaging Magnetic resonance imaging (MRI) is similar to a CAT scan in a way: both scans give you pictures of the brain. The MRI, however, uses different technology to create more detailed images. An MRI uses magnetic fields to measure the density and location of brain material. Since the MRI does not use X rays like the CAT scan does, the patient is not exposed to carcinogenic radiation. Like the CAT scan, the MRI gives doctors information about only the structure of the brain, not the function. Positron Emission Tomography A positron emission tomography (PET) scan lets researchers see what areas of the brain are most active during certain tasks. A PET scan measures how much of a certain chemical (e.g., glucose) parts of the brain are using. The more glucose used, the higher the activity. High levels of activity are indicated by warm colors like oranges and reds, while cool colors like blue and green show low activity levels. Different types of scans are used for different chemicals such as neurotransmitters, drugs, and oxygen flow. Functional MRI Functional MRI (fMRI) is a technology that combines elements of the MRI and PET scans. An fMRI scan can show details of brain structure with information about blood flow in the brain, tying brain structure to brain activity during cognitive tasks. Brain Structure and Function All the different methods of studying the brain give researchers different types of information about brain structure and function. The brain is the most complicated organ in the body. (In some ways, it is the most complex object we know of.) Because of this complexity, we need to divide the brain into separate categories to keep track of the information. Researchers have categorized hundreds of different parts and functions of different parts of the brain. When you study the brain, think about three separate major categories or sections: hindbrain, midbrain, and forebrain. Some evolutionary psychologists organize these categories into two major divisions: the “old brain” (hindbrain and midbrain) and the “new brain” (forebrain). Hindbrain The hindbrain consists of structures located on top of the spinal cord. The hindbrain is our life support system; it controls the basic biological functions that keep us alive. Some of the important specific structures within the hindbrain are the medulla, pons, and cerebellum. (Refer to Figure 4.3 for the locations of these structures.) Figure 4.3 The brain TIP Some of the descriptions of brain function may seem vague or redundant when you read about the functions of other structures. Remember that some of the ways in which the brain works are still being investigated and that the functions are just summarized here for our purposes. Keep the areas and general functions in mind instead of spending your time trying to figure out exact specific functions and locations. Medulla The medulla is involved in the control of our blood pressure, heart rate, and breathing. It is also known as the medulla oblongata and is located above the spinal cord. Pons The pons (located just above the medulla and toward the front) connects the hindbrain with the midbrain and forebrain. It is also involved in the control of facial expressions. Cerebellum The cerebellum (located on the bottom rear of the brain) looks like a smaller version of our brain stuck onto the underside of our brain. Cerebellum means “little brain.” The cerebellum coordinates some habitual muscle movements, such as tracking a target with our eyes or moving our fingers when playing the saxophone. Midbrain The midbrain is located just above the structures in the hindbrain but still below areas categorized as the forebrain. It is very small in humans, but this area of the brain controls some very important functions. In general, your midbrain coordinates simple movements with sensory information. For example, if you turn your head right now, your midbrain coordinates with muscles in your eyes to keep them focused on this text. Different parts of the midbrain are important in various muscle coordinations. For purposes of the AP test, though, you should remember that this area is between the hindbrain and the forebrain and that it integrates some types of sensory information and muscle movements. One specific structure in the midbrain you should be familiar with is the reticular formation. It is a netlike collection of cells throughout the midbrain that controls general body arousal and the ability to focus our attention. If the reticular formation does not function, we fall into a deep coma. Forebrain The various areas of the forebrain are very important to psychologists (and to students taking the AP Psychology test). Areas of the forebrain control what we think of as thought and reason. Notice in Figure 4.3 how large the forebrain is in comparison with the other areas. The size of our forebrain makes humans human, and most psychological researchers concentrate their efforts on this area of the brain. Specific areas of interest to us in the forebrain are the thalamus, hypothalamus, amygdala, and hippocampus. (The amygdala and hippocampus are not illustrated in Figure 4.3.) Thalamus The thalamus is located on top of the brain stem. It is responsible for receiving the sensory signals coming up the spinal cord and sending them to the appropriate areas in the rest of the forebrain. (See the specific areas listed in the section “Areas of the Cerebral Cortex” for examples of where some of these messages end up.) Hypothalamus The hypothalamus is a small structure right under the thalamus. The small size of the hypothalamus doesn’t mean that it is not important. The hypothalamus controls several metabolic functions, including body temperature, sexual arousal (libido), hunger, thirst, and the endocrine system. If you consider yourself a morning person or a night person, the hypothalamus might be involved since it controls our biological rhythms. TIP These parts of the brain (thalamus, hypothalamus, amygdala, and hippocampus) are grouped together and called the limbic system because they all deal with aspects of emotion and memory. When you study the parts of the brain, grouping structures together according to function should help you remember them. Amygdala and Hippocampus There are two armlike structures surrounding the thalamus. These are called the hippocampus. Structures near the end of each hippocampal arm are called the amygdala. The amygdala is vital to our experiences of emotion, and the hippocampus is vital to our memory system. Memories are not permanently stored in this area of the brain, however. Memories are processed through this area and then sent to other locations in the cerebral cortex for permanent storage. Researchers now know that memories must pass through this area first in order to be encoded because individuals with brain damage in this area are unable to retain new information. Cerebral Cortex When most people think of the human brain, they think of and picture the cerebral cortex. The gray, wrinkled surface of the brain is actually a thin (0.039-inch [1 mm]) layer of densely packed neurons. This layer covers the rest of the brain, including most of the structures we have described. When we are born, our cerebral cortex is full of neurons (more than we have now, actually), but the neurons are not yet well connected. As we develop and learn, the dendrites of the neurons in the cerebral cortex grow and connect with other neurons. This process, called pruning, forms the complex neural web you now have in your brain. The surface of the cerebral cortex is wrinkled (the wrinkles are called fissures) to increase the available surface area of the brain. The more wrinkles there are, the more surface area that is contained within our skull. If our cerebral cortex were not wrinkled, our skull would have to be 3 square feet (0.3 sq m) to hold all those neural connections! Hemispheres The cerebral cortex is divided into two hemispheres: left and right. The hemispheres look like mirror images of one another, but their similar appearance masks profound differences in function. The left hemisphere gets sensory messages and controls the motor functions of the right half of the body. The right hemisphere gets sensory messages and controls the motor functions of the left half of the body. (The idea that each side of the brain controls the opposite side of the body is called contralateral hemispheric organization.) Researchers are currently investigating other differences between the hemispheres, such as the possibility that the left hemisphere may be more active during logic and sequential tasks and the right during spatial and creative tasks. However, these generalizations need to be researched further before conclusions are drawn. This specialization of function in each hemisphere is called hemispheric specialization, or brain lateralization. Most of this research in differences between the hemispheres is done by examining split-brain patients—patients whose corpus callosum (the nerve bundle that connects the two hemispheres, see Figure 4.3) has been cut to treat severe epilepsy. The operation was pioneered by neuropsychologists Roger Sperry (1913–1994) and Michael Gazzaniga (1939–present). Split-brain patients also cannot orally report information presented only to the right hemisphere since the spoken language centers of the brain are usually located in the left hemisphere. Areas of the Cerebral Cortex When you study the cerebral cortex, think of it as a collection of different areas and specific cortices. Think of the cerebral cortex as eight different lobes, four on each hemisphere: frontal, parietal, temporal, and occipital. Some of the major functions of these parts of the brain that are relevant to the AP test are mentioned here. Any area of the cerebral cortex that is not associated with receiving sensory information or controlling muscle movements is labeled as an association area. Although specific functions are not known for each association area, these areas are very active in various human thoughts and behaviors. For example, association areas are thought to be responsible for complex, sophisticated thoughts like judgment and humor. Frontal Lobes The frontal lobes are large areas of the cerebral cortex located at the top front part of the brain behind the eyes (see Figure 4.4). The anterior or front of the frontal lobe is called the prefrontal cortex and is thought to play a critical role in directing thought processes. It is said to act as the brain’s central executive and is believed to be important in predicting consequences, pursuing goals, maintaining emotional control, and engaging in abstract thought. The story of Phineas Gage mentioned previously exemplifies some of the functions of the prefrontal cortex. Phineas Gage’s limbic system was separated from his frontal lobes in an accident. Doctors reported that he lost control of his emotions and became impulsive and animalistic. Figure 4.4 The lobes of the cerebral cortex In most people, the frontal lobe in the left hemisphere contains one of the two special areas responsible for language processing. (Some left-handed people’s language centers are in the right hemisphere.) Broca’s area (named for Paul Broca, 1824–1880) is in the frontal lobe and is responsible for controlling the muscles involved in producing speech. Damage to this area can result in the loss of this ability (a type of aphasia). (The other area is Wernicke’s area [named for Carl Wernicke, 1848–1905] and is located in the temporal lobe—see that section for more information.) A thin vertical strip at the back of the frontal lobe (farthest from the eyes, see Figure 4.4) is called the motor cortex. This part of the cerebral cortex sends signals to our muscles, controlling our voluntary movements. The top of the body is controlled by the neurons at the bottom of this cortex (by the ears), progressing down the body as you go up the cortex. So the top of the motor cortex controls the feet and toes of the body. Parietal Lobes The parietal lobes are located behind the frontal lobe but still on the top of the brain (see Figure 4.4). The parietal lobes contain the somatosensory cortex (also known as the sensory cortex), which is located right behind the motor cortex in the frontal lobe. The sensory cortex is a thin vertical strip that receives incoming touch sensations from the rest of our body. The sensory cortex is organized similarly to the motor cortex. The top of the sensory cortex receives sensations from the bottom of the body, progressing down the cortex to the bottom, which processes signals from our face and head. One fascinating phenomenon that involves the somatosensory cortex is phantom limb syndrome: if an individual loses a part of their body, like an arm or hand, the person may still perceive sensations from that lost limb because part of their somatosensory cortex is still “mapped” to the missing body part. Occipital Lobes Our occipital lobes are at the very back of our brain, farthest from our eyes. This is somewhat counterintuitive since one of the major functions of this lobe is to interpret messages from our eyes in our visual cortex. Impulses from the retinas in our eyes are sent to the visual cortex to be interpreted. Impulses from the right half of each retina are processed in the visual cortex in the right occipital lobe. Impulses from the left part of each retina are sent to the visual cortex in our left occipital lobe. TIP The term occipital looks like the word optical to some students. Thinking about this might help you remember the primary function of the occipital lobe! Temporal Lobes The temporal lobes process sound sensed by our ears. Sound waves are processed by the ears, turned into neural impulses, and interpreted in our auditory cortices. The auditory cortices are not lateralized like the visual cortices are. Sound received by the left ear is processed in the auditory cortices in both hemispheres. The second language area is located in the temporal lobe. (The first was Broca’s area in the frontal lobe.) Wernicke’s area is involved with linguistic processing via both written and spoken speech. Damage to this area would affect our ability to understand language. Our speech might sound fluent but lack the proper syntax and grammatical structure needed for meaningful communication. Brain Plasticity Researchers know some of the functions of different areas of the cerebral cortex, but they have also discovered that the brain is somewhat plastic or flexible. Although these cortices and lobes usually perform the functions already mentioned, other parts of the brain can adapt themselves to perform different functions if needed. You already know that the cerebral cortex is made up of a complex network of neurons connected by dendrites that grow to make new connections. Since dendrites grow throughout our lives, if one part of the brain is damaged, dendrites might be able to make new connections in another part of the brain that would be able to take over the functions usually performed by the damaged part of the brain. Dendrites grow most quickly in younger children. Researchers know that younger brains are more plastic and are more likely to compensate for damage.

Functional MRI
Functional MRI (fMRI) is a technology that combines elements of the MRI and PET scans. An fMRI scan can show details of brain structure with information about blood flow in the brain, tying brain structure to brain activity during cognitive tasks.
Brain Structure and Function
All the different methods of studying the brain give researchers different types of information about brain structure and function. The brain is the most complicated organ in the body. (In some ways, it is the most complex object we know of.) Because of this complexity, we need to divide the brain into separate categories to keep track of the information. Researchers have categorized hundreds of different parts and functions of different parts of the brain. When you study the brain, think about three separate major categories or sections: hindbrain, midbrain, and forebrain. Some evolutionary psychologists organize these categories into two major divisions: the “old brain” (hindbrain and midbrain) and the “new brain” (forebrain).
Hindbrain
The hindbrain consists of structures located on top of the spinal cord. The hindbrain is our life support system; it controls the basic biological functions that keep us alive. Some of the important specific structures within the hindbrain are the medulla, pons, and cerebellum. (Refer to Figure 4.3 for the locations of these structures.)
 
 Figure 4.3 The brain TIP
Some of the descriptions of brain function may seem vague or redundant when you read about the functions of other structures. Remember that some of the ways in which the brain works are still being investigated and that the functions are just summarized here for our purposes. Keep the areas and general functions in mind instead of spending your time trying to figure out exact specific functions and locations.
Medulla
The medulla is involved in the control of our blood pressure, heart rate, and breathing. It is also known as the medulla oblongata and is located above the spinal cord.
Pons
The pons (located just above the medulla and toward the front) connects the hindbrain with the midbrain and forebrain. It is also involved in the control of facial expressions.
Cerebellum
   
The cerebellum (located on the bottom rear of the brain) looks like a smaller version of our brain stuck onto the underside of our brain. Cerebellum means “little brain.” The cerebellum coordinates some habitual muscle movements, such as tracking a target with our eyes or moving our fingers when playing the saxophone.
Midbrain
The midbrain is located just above the structures in the hindbrain but still below areas categorized as the forebrain. It is very small in humans, but this area of the brain controls some very important functions. In general, your midbrain coordinates simple movements with sensory information. For example, if you turn your head right now, your midbrain coordinates with muscles in your eyes to keep them focused on this text. Different parts of the midbrain are important in various muscle coordinations. For purposes of the AP test, though, you should remember that this area is between the hindbrain and the forebrain and that it integrates some types of sensory information and muscle movements. One specific structure in the midbrain you should be familiar with is the reticular formation. It is a netlike collection of cells throughout the midbrain that controls general body arousal and the ability to focus our attention. If the reticular formation does not function, we fall into a deep coma.
Forebrain
The various areas of the forebrain are very important to psychologists (and to students taking the AP Psychology test). Areas of the forebrain control what we think of as thought and reason. Notice in Figure 4.3 how large the forebrain is in comparison with the other areas. The size of our forebrain makes humans human, and most psychological researchers concentrate their efforts on this area of the brain. Specific areas of interest to us in the forebrain are the thalamus, hypothalamus, amygdala, and hippocampus. (The amygdala and hippocampus are not illustrated in Figure 4.3.)
Thalamus
The thalamus is located on top of the brain stem. It is responsible for receiving the sensory signals coming up the spinal cord and sending them to the appropriate areas in the rest of the forebrain. (See the specific areas listed in the section “Areas of the Cerebral Cortex” for examples of where some of these messages end up.)
  
Hypothalamus
The hypothalamus is a small structure right under the thalamus. The small size of the hypothalamus doesn’t mean that it is not important. The hypothalamus controls several metabolic functions, including body temperature, sexual arousal (libido), hunger, thirst, and the endocrine system. If you consider yourself a morning person or a night person, the hypothalamus might be involved since it controls our biological rhythms.
TIP
These parts of the brain (thalamus, hypothalamus, amygdala, and hippocampus) are grouped together and called the limbic system because they all deal with aspects of emotion and memory. When you study the parts of the brain, grouping structures together according to function should help you remember them.
Amygdala and Hippocampus
There are two armlike structures surrounding the thalamus. These are called the hippocampus. Structures near the end of each hippocampal arm are called the amygdala. The amygdala is vital to our experiences of emotion, and the hippocampus is vital to our memory system. Memories are not permanently stored in this area of the brain, however. Memories are processed through this area and then sent to other locations in the cerebral cortex for permanent storage. Researchers now know that memories must pass through this area first in order to be encoded because individuals with brain damage in this area are unable to retain new information.
Cerebral Cortex
When most people think of the human brain, they think of and picture the cerebral cortex. The gray, wrinkled surface of the brain is actually a thin (0.039-inch [1 mm]) layer of densely packed neurons. This layer covers the rest of the brain, including most of the structures we have described. When we are born, our cerebral cortex is full of neurons (more than we have now, actually), but the neurons are not yet well connected. As we develop and learn, the dendrites of the neurons in the cerebral cortex grow and connect with other neurons. This process, called pruning, forms the complex neural web you now have in your brain. The surface of the cerebral cortex is wrinkled (the wrinkles are called fissures) to increase the available surface area of the brain. The more wrinkles there are, the more surface area that is
   
contained within our skull. If our cerebral cortex were not wrinkled, our skull would have to be 3 square feet (0.3 sq m) to hold all those neural connections!
Hemispheres
The cerebral cortex is divided into two hemispheres: left and right. The hemispheres look like mirror images of one another, but their similar appearance masks profound differences in function. The left hemisphere gets sensory messages and controls the motor functions of the right half of the body. The right hemisphere gets sensory messages and controls the motor functions of the left half of the body. (The idea that each side of the brain controls the opposite side of the body is called contralateral hemispheric organization.) Researchers are currently investigating other differences between the hemispheres, such as the possibility that the left hemisphere may be more active during logic and sequential tasks and the right during spatial and creative tasks. However, these generalizations need to be researched further before conclusions are drawn. This specialization of function in each hemisphere is called hemispheric specialization, or brain lateralization. Most of this research in differences between the hemispheres is done by examining split-brain patients—patients whose corpus callosum (the nerve bundle that connects the two hemispheres, see Figure 4.3) has been cut to treat severe epilepsy. The operation was pioneered by neuropsychologists Roger Sperry (1913–1994) and Michael Gazzaniga (1939–present). Split-brain patients also cannot orally report information presented only to the right hemisphere since the spoken language centers of the brain are usually located in the left hemisphere.
Areas of the Cerebral Cortex
When you study the cerebral cortex, think of it as a collection of different areas and specific cortices. Think of the cerebral cortex as eight different lobes, four on each hemisphere: frontal, parietal, temporal, and occipital. Some of the major functions of these parts of the brain that are relevant to the AP test are mentioned here. Any area of the cerebral cortex that is not associated with receiving sensory information or controlling muscle movements is labeled as an association area. Although specific functions are not known for each association area, these areas are very active in various human thoughts and behaviors. For example, association areas are thought to be responsible for complex, sophisticated thoughts like judgment
 
and humor.
Frontal Lobes
The frontal lobes are large areas of the cerebral cortex located at the top
front part of the brain behind the eyes (see Figure 4.4). The anterior or front of the frontal lobe is called the prefrontal cortex and is thought to play a critical role in directing thought processes. It is said to act as the brain’s central executive and is believed to be important in predicting consequences, pursuing goals, maintaining emotional control, and engaging in abstract thought. The story of Phineas Gage mentioned previously exemplifies some of the functions of the prefrontal cortex. Phineas Gage’s limbic system was separated from his frontal lobes in an accident. Doctors reported that he lost control of his emotions and became impulsive and animalistic.
Figure 4.4 The lobes of the cerebral cortex
In most people, the frontal lobe in the left hemisphere contains one of the
  
 two special areas responsible for language processing. (Some left-handed people’s language centers are in the right hemisphere.) Broca’s area (named for Paul Broca, 1824–1880) is in the frontal lobe and is responsible for controlling the muscles involved in producing speech. Damage to this area can result in the loss of this ability (a type of aphasia). (The other area is Wernicke’s area [named for Carl Wernicke, 1848–1905] and is located in the temporal lobe—see that section for more information.)
A thin vertical strip at the back of the frontal lobe (farthest from the eyes, see Figure 4.4) is called the motor cortex. This part of the cerebral cortex sends signals to our muscles, controlling our voluntary movements. The top of the body is controlled by the neurons at the bottom of this cortex (by the ears), progressing down the body as you go up the cortex. So the top of the motor cortex controls the feet and toes of the body.
Parietal Lobes
The parietal lobes are located behind the frontal lobe but still on the top of
the brain (see Figure 4.4). The parietal lobes contain the somatosensory cortex (also known as the sensory cortex), which is located right behind the motor cortex in the frontal lobe. The sensory cortex is a thin vertical strip that receives incoming touch sensations from the rest of our body. The sensory cortex is organized similarly to the motor cortex. The top of the sensory cortex receives sensations from the bottom of the body, progressing down the cortex to the bottom, which processes signals from our face and head. One fascinating phenomenon that involves the somatosensory cortex is phantom limb syndrome: if an individual loses a part of their body, like an arm or hand, the person may still perceive sensations from that lost limb because part of their somatosensory cortex is still “mapped” to the missing body part.
Occipital Lobes
Our occipital lobes are at the very back of our brain, farthest from our eyes. This is somewhat counterintuitive since one of the major functions of this lobe is to interpret messages from our eyes in our visual cortex. Impulses from the retinas in our eyes are sent to the visual cortex to be interpreted. Impulses from the right half of each retina are processed in the visual cortex in the right occipital lobe. Impulses from the left part of each retina are sent to the visual cortex in our left occipital lobe.
TIP
    
  The term occipital looks like the word optical to some students. Thinking about this might help you remember the primary function of the occipital lobe!
Temporal Lobes
The temporal lobes process sound sensed by our ears. Sound waves are processed by the ears, turned into neural impulses, and interpreted in our auditory cortices. The auditory cortices are not lateralized like the visual cortices are. Sound received by the left ear is processed in the auditory cortices in both hemispheres. The second language area is located in the temporal lobe. (The first was Broca’s area in the frontal lobe.) Wernicke’s area is involved with linguistic processing via both written and spoken speech. Damage to this area would affect our ability to understand language. Our speech might sound fluent but lack the proper syntax and grammatical structure needed for meaningful communication.
Brain Plasticity
Researchers know some of the functions of different areas of the cerebral cortex, but they have also discovered that the brain is somewhat plastic or flexible. Although these cortices and lobes usually perform the functions already mentioned, other parts of the brain can adapt themselves to perform different functions if needed. You already know that the cerebral cortex is made up of a complex network of neurons connected by dendrites that grow to make new connections. Since dendrites grow throughout our lives, if one part of the brain is damaged, dendrites might be able to make new connections in another part of the brain that would be able to take over the functions usually performed by the damaged part of the brain. Dendrites grow most quickly in younger children. Researchers know that younger brains are more plastic and are more likely to compensate for damage.

Transcript for:Endocrine System and Brain Functions Overview

Transcript for:
Endocrine System and Brain Functions Overview