The Limbic System

The Limbic System

The Limbic System is a complex group of interconnected structures deep within the brain that is primarily involved in emotion, motivation, memory, and certain survival behaviors (like feeding, reproduction, and fight-or-flight responses).2

It is often referred to as the emotional nervous system because of its profound influence on how we feel and react to the world.³

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🧠 Major Components and Functions

While the exact components can vary slightly depending on the source, the core structures of the limbic system and their primary functions are:

Structure	Shape/Location	Primary Role
Amygdala	Almond-shaped, near the hippocampus	Processes emotions, especially fear and anger. Essential for forming memories tied to strong emotions (emotional valence).
Hippocampus	Seahorse-shaped structure	Crucial for forming new long-term memories (memory consolidation) and spatial memory (navigation).
Hypothalamus	Sits below the thalamus	Regulates the Autonomic Nervous System (heart rate, blood pressure, body temperature) and the endocrine system (hormone release). Involved in hunger, thirst, sex drive, and the body's response to stress.
Cingulate Gyrus	Arch-shaped structure above the corpus callosum	Involved in emotion formation, pain processing, learning, and linking behavioral outcomes to motivation.

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📍 Location and Context

The limbic system structures are located on the border ("limbus" is Latin for border) between the older, subcortical areas (like the brainstem) and the newer, sophisticated cerebral cortex.⁴

It is considered an evolutionarily ancient part of the brain, involved in the basic instincts necessary for survival.⁵ It works in conjunction with other parts of the brain, particularly the prefrontal cortex, which provides the executive control necessary to regulate and modulate the emotional impulses generated by the limbic system.

OTHER SOURCES

The brain parts that you do not often see in drawings is found deep within the brain. This brain part is called the limbic system and is involved in emotions and basic drives. Some refer to the limbic system as the lower brain, not only because of where it is located, but because it handles the things about us that are a bit less civilized.

 For example, the amygdala and nucleus accumbens are important for processing fear and reward. They are also involved in drug, alcohol and other addictions. The cingulate gyrus runs the day to day activities of the body that we do not directly control, like heart rate and blood pressure.

One interesting part of the limbic system that actually resides in the parietal cortex is called the hippocampus. The hippocampus is the brain part that forms memories. You have one of these on each side of the brain. 

If one hippocampus is injured, say by a stroke, the other one will still allow your brain to make memories. However, if both hippocampi are removed, as was once done through surgery, then you cannot form new memories! 

This horrible thing happened to a person that underwent surgery to prevent almost continuous, life-ruining seizures. 

After the surgery, it was found that the person could only remember things that happened prior to the surgery and could not make new memories. 

Each day, in fact each new moment was a confusing, perpetual question of How did I get here?

 Needless to say this surgery never happens anymore but this terribly unfortunate occurrence demonstrates the importance of the hippocampus in memory.

Diagram of Brain...

Diagram-of-brain-frontal-lobe

DIAGRAM OF BRAIN : CEREBELLUM

DIAGRAM OF BRAIN : CEREBELLUM

Diagram of the Brain: Cerebellum

The human brain is divided into several major regions, each responsible for specific functions. One of these important regions is the Cerebellum, located at the lower back part of the brain, just beneath the Occipital Lobe and behind the Brainstem.

The Cerebellum is often referred to as the “little brain” because of its rounded, wrinkled structure that resembles a smaller version of the main brain. It plays a vital role in movement coordination, balance, posture, and motor learning.

In a typical brain diagram:

• The Frontal Lobe is at the front, controlling decision-making, movement, and personality.

• The Parietal Lobe is at the top-middle, handling touch, pressure, and spatial awareness.

• The Temporal Lobe is on the side, involved in hearing, memory, and speech.

• The Occipital Lobe is at the back, responsible for vision.

• The Cerebellum, highlighted near the lower rear of the brain, appears as a distinct section with horizontal grooves.

It is connected to the brainstem and ensures that all physical movements are smooth and precise. Damage to the cerebellum can lead to loss of balance, uncoordinated movement, or difficulty walking.

DIAGRAM OF BRAIN : CEREBELLUM Video

DIAGRAM OF BRAIN (Temporal Lobe)

DIAGRAM OF BRAIN: TEMPORAL LOBE

Temporal Lobe Overview

• Location: Lower middle part of the brain, beneath the lateral sulcus (Sylvian fissure), roughly behind the temples.

• Function:

  • Auditory processing – interprets sounds and language.

  • Memory formation – houses the hippocampus.

  • Emotion processing – connected with the limbic system.

  • Understanding language (Wernicke’s area in the left hemisphere).

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Simple Diagram of the Brain Showing the Temporal Lobe

Top View (simplified):

       Frontal Lobe
       ┌───────────┐
       │           │
       │ Frontal   │
       │           │
       └─────┬─────┘
             │
     Parietal │
       Lobe   │
 ┌───────────┴───────────┐
 │                       │
 │     Temporal Lobe     │  <- beneath lateral sulcus
 │   (auditory & memory)│
 └───────────┬───────────┘
             │
        Occipital Lobe

Side View of Brain (simplified):

      [Frontal Lobe]
           ____
          /    \
         |      |
         |      | 
         |______|
         |      |
         |      |  
         |Temporal| <- Temporal Lobe (side/lower brain)
         | Lobe  |
         \______/
         |      |
         |Occipital|
         |  Lobe   |
         \______/

Tip: The temporal lobe sits below the parietal and frontal lobes, near your ears, which is why it’s heavily involved in hearing.

Temporal Lobe - There are two temporal lobes, one on each side of the brain located at about the level of the ears. These lobes allow a person to tell one smell from another and one sound from another. They also help in sorting new information and are believed to be responsible for short-term memory.

Brain Right Lobe - Mainly involved in visual memory (i.e., memory for pictures and faces).

Brain Left Lobe - Mainly involved in verbal memory (i.e., memory for words and names).

Diagram of Brain

diagramofbrain-/thalamus.

DIAGRAM OF BRAIN (Parietal Lobe)

DIAGRAM OF BRAIN : PARIETAL LOBE

Parietal Lobe Overview

• Location: Upper middle part of the brain, behind the frontal lobe and above the occipital lobe.

• Function:

  • Processes sensory information (touch, pressure, temperature, pain).

  • Spatial awareness and navigation.

  • Hand-eye coordination and manipulation of objects.

  • Understanding language and mathematics (in some areas, like the left hemisphere).

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Simple Diagram of the Brain Showing the Parietal Lobe

         Frontal Lobe
       ┌───────────────┐
       │               │
       │   Frontal     │
       │               │
       └──────┬────────┘
              │
   Parietal   │
   Lobe       │
 ┌────────────┴───────────┐
 │                        │
 │   Sensory Processing   │
 │                        │
 └────────────┬───────────┘
              │
         Occipital Lobe

Or if visualized on a side-view of the brain:

Side View of Brain:

      [Frontal Lobe]
           ____
          /    \
         |      |
         |      |  <- Parietal Lobe (top-middle)
         |______|
         |      |
         |      |  <- Occipital Lobe (back)
         \______/ 

Tip: On an actual brain, the central sulcus separates the frontal lobe (motor functions) from the parietal lobe (sensory functions).

Parietal Lobe - One of the two parietal lobes of the brain located behind the frontal lobe at the top of the brain.

Parietal Lobe, Right - Damage to this area can cause visuo-spatial deficits (e.g., the patient may have difficulty finding their way around new, or even familiar, places).

Parietal Lobe, Left - Damage to this area may disrupt a patient's ability to understand spoken and/or written language.

The parietal lobes contain the primary sensory cortex which controls sensation (touch, pressure). Behind the primary sensory cortex is a large association area that controls fine sensation (judgment of texture, weight, size, shape)

Diagram of Brain Video
diagram-of-brain-cerebellum.

DIAGRAM OF BRAIN (Occipital Lobe)

The occipital lobe is the smallest of the four lobes of the brain, located at the back of the skull, and is primarily responsible for visual processing. It receives visual information from the eyes and processes it to allow us to see, recognize objects, and understand spatial relationships. 

Key Functions of the Occipital Lobe:

Visual Processing:

The occipital lobe is the main area for visual processing, including color, form, and motion. 

Visual Perception:

It allows us to perceive and interpret what we see, including recognizing objects, faces, and places. 

Spatial Awareness:

It helps us understand the location of objects in our environment and our own position in space. 

Coordination with other lobes:

The occipital lobe works with other brain areas, like the parietal and temporal lobes, to enhance visual experiences and integrate visual information with other senses. 

Memory and Learning:

It plays a role in visual memory and learning, including recognizing familiar objects and scenes. 

Potential Issues from Occipital Lobe Damage:

Visual Deficits: Damage can lead to various visual impairments, such as blurred vision, color blindness, and difficulty recognizing objects or faces. 

Spatial Disorientation: Difficulty locating objects or navigating the environment. 

Reading and Writing Problems: Inability to recognize or process written words. 

Visual Hallucinations: Experiencing visual sensations that are not actually present. 

Epilepsy: Seizures can originate in the occipital lobe. 

Location and Structure:

The occipital lobe sits at the back of the head, beneath the parietal and temporal lobes. 

It is separated from the parietal lobe by the parietooccipital sulcus. 

The occipital lobe contains the primary visual cortex (V1), which receives initial visual input, and secondary visual areas, which further process visual information. 

DIAGRAM OF BRAIN

The occipital lobe is the smallest of the four brain lobes, situated at the rear of the skull, and is chiefly responsible for visual processing. It receives visual data from the eyes and processes it, enabling us to see, identify objects, and comprehend spatial relationships.

Key Functions of the Occipital Lobe:

Visual Processing:

The occipital lobe serves as the primary region for visual processing, encompassing color, shape, and movement.

Visual Perception:

It enables us to perceive and interpret visual stimuli, including the recognition of objects, faces, and locations.

Spatial Awareness:

It assists in understanding the positioning of objects within our surroundings and our own location in space.

Coordination with Other Lobes:

The occipital lobe collaborates with other brain regions, such as the parietal and temporal lobes, to enhance visual experiences and integrate visual data with other sensory inputs.

Memory and Learning:

It contributes to visual memory and learning, including the recognition of familiar objects and scenes.

Potential Issues from Occipital Lobe Damage:

Visual Deficits: Damage may result in various visual impairments, including blurred vision, color blindness, and challenges in recognizing objects or faces.

Spatial Disorientation: Difficulty in locating objects or navigating through the environment.

Reading and Writing Problems: Inability to recognize or process written text.

Visual Hallucinations: Experiencing visual sensations that do not actually exist.

Epilepsy: Seizures may originate in the occipital lobe.

Location and Structure:

The occipital lobe is positioned at the back of the head, beneath the parietal and temporal lobes.

It is separated from the parietal lobe by the parietooccipital sulcus.

The occipital lobe houses the primary visual cortex (V1), which receives the initial visual input, along with secondary visual areas that further process visual information.

DIAGRAM OF BRAIN (Frontal Lobe)

DIAGRAM OF BRAIN: FRONTAL LOBE

Comprehensive Functions and Anatomy of the Frontal Lobe

The Frontal Lobe is the largest and most anterior region of the cerebral cortex, often described as the brain's executive control center. It integrates complex cognitive processes and coordinates our actions with our intentions.

1. Motor Control Centers

The back strip of the frontal lobe, located just in front of the central sulcus, is dedicated to controlling voluntary movement.

• Primary Motor Cortex (M1): Located in the Precentral Gyrus, this area is the source of the main motor commands that travel down to the spinal cord (via the corticospinal tract). It is organized somatotopically, meaning there is a complete but distorted map of the body (the motor homunculus) where different body parts are controlled by specific cortical areas.

• Premotor Cortex (PMC): Involved in the planning and orientation of movement, especially movements guided by external stimuli. It helps select appropriate movements based on visual or sensory information.

• Supplementary Motor Area (SMA): Critical for planning sequences of movements (like playing a musical instrument) and coordinating movements that involve both sides of the body (e.g., clapping). It is crucial for movements initiated internally, based on an individual's will.

2. Executive Functions and Cognition

The anterior portion of the frontal lobe is known as the Prefrontal Cortex (PFC), responsible for higher-order cognitive abilities that govern behavior.

Function	Description
Planning & Goal-Setting	Formulating strategies, anticipating consequences, and creating step-by-step plans to achieve a goal.
Working Memory	Holding and manipulating short-term information necessary for tasks like mental math or following multi-step directions.
Inhibition & Impulse Control	Suppressing inappropriate or irrelevant thoughts and actions, allowing for focused and goal-directed behavior.
Cognitive Flexibility	The ability to switch between different concepts, tasks, or rules based on context.
Attention & Concentration	Maintaining focus on a task and filtering out distractions.

3. Language Production

• Broca's Area: Located in the lower portion of the left frontal lobe (for most people), this region is essential for the production of speech. Damage to this area results in expressive aphasia, where a person knows what they want to say but struggles to form words and sentences.

4. Personality, Emotion, and Judgment

The frontal lobe is instrumental in shaping personality and regulating emotional and social behavior.

• Personality: It integrates information to determine our unique temperament, disposition, and emotional stability.

• Social and Moral Reasoning: It allows us to understand social rules, make ethical judgments, and monitor the appropriateness of our own behavior in a social context.

In summary, the frontal lobe functions as the brain's conductor, coordinating a vast orchestra of thoughts, emotions, and movements to execute complex, intentional, and socially appropriate behavior.

The frontal lobe, positioned at the forefront of the brain just behind the forehead, is the largest among the four brain lobes and is integral to numerous higher-level cognitive functions, personality traits, and voluntary movements. It is frequently regarded as the brain's command center for behavior and emotions.

Key Functions of the Frontal Lobe:

Cognitive Functions:

The frontal lobe is crucial for activities such as working memory, reasoning, judgment, planning, and problem-solving.

Movement:

It governs voluntary movements through the primary motor cortex and also contributes to the planning and coordination of movements via the premotor cortex.

Language:

It contains Broca's area, which is essential for the production of speech.

Social and Emotional Behavior:

The frontal lobe plays a role in the regulation of emotions, social interactions, and decision-making. It aids in impulse control, managing social behavior, and comprehending the consequences of actions.

Personality:

Injury to the frontal lobe can result in notable alterations in personality, including apathy, impulsivity, and diminished social skills.

Location:

The frontal lobe is located at the front of the brain, directly behind the forehead. It is separated from the parietal lobe by the central sulcus and from the temporal lobe by the lateral sulcus.

Clinical Significance:

Frontal Lobe Syndrome:

Injury to the frontal lobe can lead to various cognitive and behavioral deficits, collectively referred to as frontal lobe syndrome. Symptoms may encompass apathy, impulsivity, impaired judgment, and personality changes.

Frontal Lobe Seizures:

These seizures may present with a range of symptoms, including head and eye movements, difficulties in speech, and atypical body movements.

Frontal Headaches:

Headaches in the forehead or temple area can sometimes be linked to frontal lobe problems, although numerous other causes may exist.

In conclusion, the frontal lobe is a crucial brain region responsible for a broad spectrum of higher-level cognitive, behavioral, and motor functions. Damage to this area can result in significant impairments in these areas. 

Frontal Lobe - Front part of the brain; involved in planning, organizing, problem solving, selective attention, personality and a variety of "higher cognitive functions" including behavior and emotions.


The anterior (front) portion of the frontal lobe is called the prefrontal cortex. It is very important for the "higher cognitive functions" and the determination of the personality.

The posterior (back) of the frontal lobe consists of the premotor and motor areas. Nerve cells that produce movement are located in the motor areas. The premotor areas serve to modify movements.

The frontal lobe is divided from the parietal lobe by the central culcus.
Diagram of Brain.

diagram-of-brain.

HOW THE BRAIN CONTROL MOVEMENT

HOW THE BRAIN CONTROL MOVEMENT

The brain controls movement through a complex, hierarchical system involving multiple regions that The brain controls voluntary movement through a precisely organized, hierarchical system that begins with intent and ends with the contraction of specific muscles. This is primarily executed via the motor pathways (descending tracts) involving several key brain regions.

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🧠 Key Brain Regions for Movement

Movement is not controlled by a single area, but by a network of structures that coordinate planning, initiation, execution, and correction.

1. Cerebral Cortex (The Planner and Initiator):

   • Premotor Cortex and Supplementary Motor Area: These areas in the frontal lobe are involved in the planning and sequencing of complex movements (e.g., deciding the steps to pick up a cup).

   • Primary Motor Cortex (M1): Located in the frontal lobe's precentral gyrus, this is where the final, specific commands to initiate a voluntary movement are generated. It operates a motor homunculus, a map where different parts of the cortex control specific body parts (the hands and face take up the most space).

2. Cerebellum (The Coordinator and Corrector):

   • The cerebellum is essential for coordination, balance, and fine-tuning movement. It constantly compares the intended movement from the cortex with the actual movement reported by the body's sensory feedback, correcting any errors in real-time.

3. Basal Ganglia (The Regulator):

   • A group of deep structures that act as a gate, regulating the initiation and suppression of movements. They select the appropriate motor program and inhibit unwanted movements, which is why damage here (as in Parkinson's disease) leads to tremors and difficulty initiating movement.

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⚡ The Motor Pathway (The Command Line)

The signal to move travels from the cortex down the primary descending pathway, the Corticospinal Tract, using two main types of neurons:

1. Upper Motor Neuron (UMN)

• Origin: The cell body of the UMN is located in the Primary Motor Cortex.

• Decussation (The Crossover): The axon of the UMN travels down through the brainstem. In the medulla oblongata, the majority of the fibers cross over (decussate) to the opposite side of the central nervous system.

• Descent: The pathway continues down the spinal cord on the side opposite to its origin (the contralateral side). This is why the left side of your brain controls the right side of your body, and vice-versa.

2. Lower Motor Neuron (LMN)

• Synapse: The UMN axon synapses with the LMN cell body in the ventral horn of the spinal cord (or in the brainstem for face/neck movements).

• Action: The LMN axon then leaves the spinal cord and travels through peripheral nerves to the skeletal muscle, where it releases neurotransmitters (acetylcholine) at the neuromuscular junction, causing the muscle to contract.

Diagram of Brain

The area of the brain that controls movement is in a very narrow strip that goes from near the top of the head right down along where your ear is located. 

It's called the motor strip. If I injure that area, I'll have problems controlling half of my body. If I have a stroke in the left hemisphere of my brain, the right side of the body will stop working. 

If I have an injury to my right hemisphere in this area, the left side of my body stops working (remember, we have two brains). This is why one half of the face may droop when a person has had a stroke. Diagram of Brain

MOVEMENT VIDEO :

GETTING INFORMATION IN AND OUT OF THE BRAIN

GETTING INFORMATION IN AND OUT OF THE BRAIN

Getting information into and out of the brain relies on the Central Nervous System (CNS) and the Peripheral Nervous System (PNS) working together via specialized neural pathways.

The flow of information is categorized into two main directions:

1. Input (Afferent/Sensory): Information coming into the CNS (brain and spinal cord).

2. Output (Efferent/Motor): Information going out of the CNS to the body's effectors (muscles and glands).

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👂 Input: Sensory (Afferent) Pathways

Sensory information from the environment (e.g., sight, touch, pain) travels toward the brain via sensory neurons.

• Peripheral Receptors: Specialized sensory receptors in the skin, eyes, ears, and internal organs detect stimuli (e.g., pressure, light, chemical signals).

• Transmission: This detection generates an electrical impulse (action potential) in a sensory neuron.

• Ascending Tracts: The impulse travels along the nerve fibers (axons) through peripheral nerves and then enters the spinal cord or brainstem. Once inside the spinal cord, it travels toward the brain in organized bundles called ascending tracts.

  • Body Below the Neck: Information ascends through the spinal cord. Major pathways, like the Spinothalamic Tract (for pain and temperature) and the Dorsal Column System (for fine touch and proprioception), carry the signal.

  • Head and Neck: Information is carried directly to the brainstem via the Cranial Nerves (e.g., the Optic Nerve for vision, the Vestibulocochlear Nerve for hearing/balance).

• Processing Centers: The sensory signal is typically relayed in the thalamus (the brain's major relay center) before reaching its final destination in the cerebral cortex (e.g., the Somatosensory Cortex in the parietal lobe for touch, the Visual Cortex in the occipital lobe for sight).

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💪 Output: Motor (Efferent) Pathways

Instructions for movement and gland function travel away from the brain to the body's muscles and glands via motor neurons.

• Initiation: Voluntary movement instructions are typically initiated in the cerebral cortex, mainly the Primary Motor Cortex in the frontal lobe.

• Descending Tracts: The instructions travel down from the cortex as electrical impulses along upper motor neurons through the brainstem and into the spinal cord in bundles called descending tracts. The most famous of these is the Corticospinal Tract, which controls voluntary, skilled movements of the limbs.

• Relay in Spinal Cord: In the spinal cord, the upper motor neuron synapses (communicates) with a lower motor neuron.

• Final Destination: The lower motor neuron's axon exits the spinal cord and travels through peripheral nerves to connect directly with the muscle fiber or gland, causing it to contract or secrete.

This constant, rapid flow of input (sensory) and output (motor) allows the brain to perceive the environment, process the information, and execute appropriate and timely responses.

How does information come into the brain? 

A lot of information comes in through the spinal cord at the base of the brain. Think of a spinal cord as a thick phone cable with thousands of phone lines. If you cut that spinal cord, you won't be able to move or feel anything in your body. Information goes OUT from the brain to make body parts (arms and legs) do their job. 

There is also a great deal of INCOMING information (hot, cold, pain, joint sensation, etc.). Vision and hearing do not go through the spinal cord but go directly into the brain. That’s why people can be completely paralyzed (unable to move their arms and legs) but still see and hear with no problems.

Information enters from the spinal cord and comes up the middle of the brain. It branches out like a tree and goes to the surface of the brain. The surface of the brain is gray due to the color of the cell bodies (that's why it's called the gray matter). The wires or axons have a coating on them that's colored white (called white matter).

GETTING INFORMATION IN AND OUT OF THE BRAIN VIDEO :