Brain Regions - part1 (OLI)


If you were someone who understood brain anatomy and were to look at the brain of an animal that you had never seen before, you would nevertheless be able to deduce the likely capacities of the animal because the brains of all animals are much alike in overall form. In each animal the brain is layered, and the basic structures of the brain are similar.


The Old Brain: Wired for Survival

The innermost structures of the brain—the parts nearest the spinal cord—are the oldest part of the brain, and these areas carry out the same functions they did for our distant ancestors. The “old brain” regulates basic survival functions, such as breathing, moving, resting, and feeding, and creates our experiences of emotion. Mammals, including humans, have developed further brain layers that provide more advanced functions—for instance, better memory, more sophisticated social interactions, and the ability to experience emotions. Humans have a large and highly developed outer layer known as the cerebral cortex, which makes us particularly adept at these processes.

The brain stem is the oldest and innermost region of the brain. It controls the most basic functions of life, including breathing, attention, and motor responses. The brain stem begins where the spinal cord enters the skull and forms the medulla, the area of the brain stem that controls heart rate and breathing. In many cases, the medulla alone is sufficient to maintain life—animals that have their brains severed above the medulla are still able to eat, breathe, and even move. The spherical shape above the medulla is the pons, a structure in the brain stem that helps control the movements of the body, playing a particularly important role in balance and walking. The pons is also important in sleeping, waking, dreaming, and arousal.

Running through the medulla and the pons is a long, narrow network of neurons known as the reticular formation. The job of the reticular formation is to filter out some of the stimuli that are coming into the brain from the spinal cord and to relay the remainder of the signals to other areas of the brain. The reticular formation also plays important roles in walking, eating, sexual activity, and sleeping. When electrical stimulation is applied to the reticular formation of an animal, it immediately becomes fully awake, and when the reticular formation is severed from the higher brain regions, the animal falls into a deep coma.



The brain stem is an extension of the spinal cord, including the medulla, the pons, the thalamus, and the reticular formation.


Two structures near the brain stem are also vital for basic survival functions. The thalamus is the egg-shaped structure sitting just above the brain stem that applies still more filtering to the sensory information coming from the spinal cord and through the reticular formation, and it relays some of these remaining signals to the higher brain levels. The thalamus also receives some of the higher brain’s replies, forwarding them to the medulla and the cerebellum. The thalamus is also important in sleep because it shuts off incoming signals from the senses, allowing us to rest.

The cerebellum (literally, “little brain”) consists of two wrinkled ovals behind the brain stem. It functions to coordinate voluntary movement. People who have damage to the cerebellum have difficulty walking, keeping their balance, and holding their hands steady. Consuming alcohol influences the cerebellum, which is why people who are drunk have difficulty walking in a straight line. Also, the cerebellum contributes to emotional responses, helps us discriminate between different sounds and textures, and is important in learning.


Did I get this

What is the area of the brain that controls heart rate and breathing?
medulla OR thalamus OR pons OR reticulat formation
The medulla is essential for the necessary functions of life.



What is the area of the brain that controls alertness and attention?
medulla OR thalamus OR pons OR reticulat formation
The reticular formation also plays important roles in walking, eating, sexual activity, and sleeping.



What is the egg-shaped structure above the brain stem that filters sensory information coming up from the spinal cord and relays signals to the higher brain levels?
medulla OR thalamus OR pons OR reticulat formation
The thalamus is also important in sleep because it turns off incoming signals from the senses, allowing us to rest.



What is the structure in the brain stem that helps control the movements of the body and plays a particularly important role in balance and walking?
medulla OR thalamus OR pons OR reticulat formation
The pons is also important in sleep, waking, dreaming, and arousal.


The Limbic System


Whereas the primary function of the brain stem is to regulate the most basic aspects of life, including motor functions, the limbic system is largely responsible for memory and emotions, including our responses to reward and punishment. The limbic system is a set of distinct and important brain structures located beneath and around the thalamus. Limbic system structures interact with the rest of the brain in complex ways, and they are extremely important for memory and control of emotional responses. They include the amygdala, the hypothalamus, and the hippocampus, among other structures.
This diagram shows the major parts of the limbic system,
as well as the pituitary gland, which is controlled by it.

The amygdala consists of two almond-shaped clusters (amygdala comes from the Latin word for almond) and is primarily responsible for regulating our perceptions of and reactions to aggression and fear. The amygdala has connections to other bodily systems related to fear, including the sympathetic nervous system (which we will see later is important in fear responses), facial responses (which perceive and express emotions), the processing of smells, and the release of neurotransmitters related to stress and aggression. 
In a 1939 study, Klüver and Bucy damaged the amygdala of an aggressive rhesus monkey. They found that the once angry animal immediately became passive and no longer responded to fearful situations with aggressive behavior. Electrical stimulation of the amygdala in other animals also influences aggression. In addition to helping us experience fear, the amygdala helps us learn from situations that create fear. When we experience events that are dangerous, the amygdala stimulates the brain to remember the details of the situation so that we learn to avoid it in the future.

Located just under the thalamus (hence its name), the hypothalamus is a brain structure that contains a number of small areas that perform a variety of functions. Through its many interactions with other parts of the brain, the hypothalamus helps regulate body temperature, hunger, thirst, and sex drive and responds to the satisfaction of these needs by creating feelings of pleasure.

The hippocampus consists of two “horns” that curve back from the amygdala. The hippocampus is important in storing information in long-term memory. If the hippocampus is seriously damaged on both sides of the brain, a person may be unable to store new long-term memories, living instead in a strange world where everything he or she experiences just fades away, even while older memories from the time before the damage are untouched.



Did I get this

David was hospitalized after a car accident, and due to injury to his ________, he has trouble with newer memories but still retains older memories.
hypothalamus OR hippocamus OR amygdala
Damage to the hippocampus affects the retention of newer memories, but older memories are still stored, unaffected.



What is the area of the brain that controls alertness and attention?
medulla OR thalamus OR pons OR reticulat formation
The amygdala is related to emotional expression of anger and rage, but also in humans helps us to recognize emotions in others.



What is the egg-shaped structure above the brain stem that filters sensory information coming up from the spinal cord and relays signals to the higher brain levels?
medulla OR thalamus OR pons OR reticulat formation
The hypothalamus is involved in the regulation of basic drives.

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