BBB - Brain Regions and Structures Lesson

Learning Targets:

• Describe the roles of the hindbrain, midbrain, and forebrain in influencing behavior and mental processes.
• Identify the parts of the brainstem and describe the roles of the brainstem, thalamus, reticular formation, and cerebellum.
• Outline the components and functions of the limbic system.
• Describe the four lobes of the cerebral cortex and explain the functions of the motor cortex, somatosensory cortex, and association areas.

Courtesy of the AP psychology course and exam description, effective fall 2024. (n.d.). Links to an external site.

 

The Anatomy of the Brain

Complete the activity below to learn about the parts of the brain and their functions.

 

Understanding the Brain's Influence on Behavior and Mental Processes

The brain, our body's command center, can be divided into three main parts: the hindbrain, midbrain, and forebrain. The hindbrain houses the brainstem, which regulates vital functions like breathing, sleeping, coordination, and balance. Moving up, the midbrain bridges the hindbrain and forebrain, controlling some movements and transmitting sensory information crucial for sight and sound. Lastly, the forebrain controls intricate cognitive tasks, sensory processing, and voluntary muscle movements. As our brains evolved, we can see changes in structure and function that reflect the development of more complex behaviors and thoughts, highlighting the fascinating journey of the human brain through evolution.

The Brainstem

The brainstem is a crucial region located at the innermost part of the brain. At its base is the medulla, a slight swelling in the spinal cord as it enters the skull. The medulla is responsible for controlling essential functions like heartbeat and breathing. The pons are situated just above the medulla, crucial for coordinating movements and regulating sleep patterns. In addition to the medulla and pons, other vital areas of the brainstem include the thalamus, reticular formation, and cerebellum.

Thalamus

The thalamus, located at the top of the brainstem, acts as the brain's sensory control center, receiving information from all senses except smell. It then routes this information to the relevant brain regions for processing. Additionally, the thalamus plays a crucial role in regulating awareness, attention, motivation, and emotion. The reticular formation, another part of the brainstem, controls arousal and attention. The cerebellum, located at the back of the brainstem, is vital in coordinating movement and balance.

 Reticular Formation

Inside the brainstem between your ears lies the reticular formation. This is a nerve network which is governed by what's called the reticular activating system, extending from the spinal cord through the thalamus. As the spinal cord sensory input flows up to the thalamus, some of it travels to the reticular formation. The reticular formation also controls arousal, our state of alertness. For example, when you wake up in the morning to your alarm clock, it's the reticular formation that helps you quickly become alert and ready to start your day.

Cerebellum

The cerebellum, or "little brain," is located at the bottom or rear of our brain and looks like a little version of the brain. It controls balance, muscle tone, coordination, and fine motor skills. If you damage the cerebellum, the result can be jerky movements.

Medulla Oblongata

The medulla oblongata is a long stretch of cords located just above the spinal cord in charge of automatic functions and vital reflexes. The medulla oblongata controls blood pressure, breathing, heart rate, digestion, sneezing, coughing, and vomiting. Damage to the medulla can result in death.

Pons

The pons is the uppermost hindbrain level located just above the medulla. It acts as a bridge connecting the hindbrain with the midbrain and forebrain. Information from higher brain regions travels to the cerebellum through the pons. It involves body movements, sensations, facial expressions, and REM sleep.

Understanding the Limbic System

The limbic system is a crucial part of the brain that borders the brain stem and plays a significant role in learning, memory, and emotions. It consists of critical structures such as the hypothalamus, the hippocampus, and the amygdala. These structures are responsible for regulating emotions, drives, and memory formation. In addition to the mentioned components, the limbic system also includes the thalamus and the pituitary gland, working together to influence various behavioral and psychological functions in individuals.

The Amygdala 

One key component of the limbic system is the amygdala, a cluster of neurons in the brain that is responsible for processing emotions like fear, anger, and disgust. The amygdala also helps us remember sensory information such as smells, sights, and sounds. For example, when the amygdala is damaged, individuals may have reduced responses to fear-inducing stimuli. Despite its importance in emotions, the brain is complex and interconnected, so the amygdala is also involved in various other mental processes beyond just emotions.

The Hypothalamus

 The hypothalamus, located beneath the thalamus, is about the size of a pea. The hypothalamus contains over forty neural pathways and regulates the autonomic nervous system. Additionally, it controls essential functions such as the suprachiasmatic nucleus, which regulates sleep/wake cycles, and the pituitary gland. Some neural clusters within the hypothalamus influence hunger, while others regulate thirst, body temperature, and sexual behavior. Working together, these clusters help maintain a balanced internal state by monitoring blood chemistry and responding to signals from other brain parts. An example of the hypothalamus is when you feel thirsty, signaling the need to drink water to maintain proper hydration.

The Hippocampus

The hippocampus is situated within the temporal lobe. It processes sensory information into short-term or long-term memories or sometimes out of memory altogether. It is particularly vital for creating conscious, explicit memories, making it essential for our ability to recall facts and events. For example, individuals who undergo surgery or experience injury that affects the hippocampus may struggle with forming new memories. Additionally, as we age, the hippocampus tends to decrease in size and function, contributing to cognitive decline.

Watch the video on emotions and the limbic system below.

The Cerebral Cortex

The cerebral cortex is made up of densely packed neurons called "gray matter". These neurons work together to create neural networks. The cerebral cortex is characterized by grooves and bulges and is divided into two hemispheres connected by the corpus callosum (A thick bundle of axons that link the right and left hemispheres of the brain). It is the part of the brain that makes us humans responsible for thought, planning, perception, and consciousness.The cerebral cortex is divided up into four lobes or areas. Each has a distinct function and is divided by fissures. Any areas of the cerebral cortex not dealing with our senses or muscle movement are called association areas.

The Lobes

Click on these dialogue cards to learn more about the lobes and their functions.

Exploring Association Areas in the Brain

Association areas play a crucial role in the cerebral cortex, focusing on higher mental functions rather than primary motor or sensory tasks. These areas, present in all four brain lobes, contribute to activities such as learning, remembering, thinking, and speaking. For instance, the prefrontal cortex in the frontal lobes supports judgment, planning, social interactions, and the processing of new memories. A classic example illustrating the impact of frontal lobe damage on personality and inhibitions is the Phineas Gage case study. Additionally, the parietal lobes facilitate mathematical and spatial reasoning, while the association area on the underside of the right temporal lobe aids in facial recognition. It's important to note that our mental functions are distributed across various brain regions, with functional connectivity playing a key role. Brain scans reveal the collaboration among different areas and neural networks to support functions like memory, language, attention, and social skills.

 

 

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