The Nervous System: A Basic Overview

The human body is an extremely complex organism comprising of various organ systems that work together to enable survival and optimal functioning. Each system has a specific role and organs which enable that role. The nervous system coordinates the activity of all these other systems in the body and includes the brain, spinal cord as well as all the nerves connected throughout the body.

THE BRAIN

The brain is the most complex organ in the entire world, remaining largely mysterious despite ongoing efforts to comprehend it. It controls every aspect of our body, with different regions specialising in distinct functions, yet transcends these individual areas, emerging as something far greater than the sum of its parts. The brain communicates through a vast network of 86 billion neurons via electrical and chemical signals, sending brain waves across multiple dimensions: top-down, anterior-posterior, and right-left.

Communication

Neurons communicate through electrical impulses, or action potentials, generated by the movement of ions (sodium, potassium, calcium) across their membranes. This electrical charge (action potential) travels down the axon toward the synapse. When it reaches the end of the neuron, it triggers the release of chemicals (neurotransmitters).

Neurotransmitters

There are 100's of neurotransmitters (brain chemicals) but the most common ones are:

Acetylcholine: Learning, memory, attention, muscle contraction.
Dopamine: Reward, motivation, pleasure, motor control.
Serotonin: Mood, sleep, appetite, digestion, emotional regulation.
GABA: Relaxation, inhibitory control, prevents overstimulation.
Glutamate: Learning, memory, excitatory signaling.
Norepinephrine: Fight-or-flight response, arousal, attention, energy.
Epinephrine: Stress response, increases heart rate and energy.
Endorphins: Pain relief, euphoria.

With the most common neuropeptide that usually gets lumped with the transmitters:

Oxytocin: Bonding, trust, social connection.

These chemicals jump across the synapse and bind to receptors on the dendrites of the next neuron, passing along the signal. When many neurons fire together in patterns, their electrical activity combines and creates brain waves, which can be measured as overall rhythms of brain activity.

Brain Waves

Gamma Waves (40 - 100 Hz): Gamma Brain Waves are the fastest brainwaves (high frequency) and the most recently discovered brain wave state, relate to simultaneous processing of information from different brain areas. These are involved in higher processing tasks as well as cognitive functioning. This is important for learning, memory and information processing.

Beta Waves (12 – 40 Hz): Beta Brain Waves are associated with normal waking consciousness and a heightened state of alertness, logic and critical reasoning. Having the right amount of beta allows us to focus on our task whether at school, work or sports performance. However, exposing too much beta waves also results in too much stress. Stress produces stress chemicals like Cortisol which is really harmful to our body if it’s too much.

Alpha Waves (8 – 12 Hz): Alpha Brain Waves are dominant during quietly flowing thoughts, while you are in deep relaxation, or when you are slipping into a lovely daydream or during light meditation. Alpha is the frequency between our conscious thinking and subconscious mind. This is the Flow State Zone.

Theta Waves (4 – 8 Hz): Theta Brain Waves occur most often in sleep but are also dominant during deep meditation. In theta, we are in a dream; vivid imagery, intuition and information beyond normal consciousness awareness. It helps us improve our intuition, creativity, and makes us feel more natural. This is also the Flow State Zone.

Delta Waves (0 – 4 Hz): Delta Brain Waves are the slowest but loudest brainwaves (low frequency). It is experienced in a deep, dreamless sleep and in very deep, transcendental meditation. These are also found most often in infants as well as young children. Deep sleep is important for the healing process – as it’s linked with deep healing and regeneration.

Brain Dimensions and Areas

1. Top-Down:

Human/Cognitive Processes (Neocortex): Located in the outermost layer of the brain, responsible for higher-order cognitive functions such as reasoning, language, and conscious thought.
Mammalian/Emotional Processes (Limbic System): Situated beneath the neocortex, involved in emotions, memory, and motivation.
Reptilian/Survival Processes (Brainstem and Basal Ganglia): Located at the base of the brain, responsible for basic survival functions, including heartbeat, breathing, and reflexes.

2. Anterior - Posterior

Anterior (Front) - Cognitive Processes (Prefrontal Cortex): Involved in decision-making, planning, reasoning, and executive control.
Middle - Motor Processes (Motor Cortex): Responsible for planning and executing voluntary movements.
Posterior (Back) - Sensory Processes: Involved in processing and interpreting sensory information from the environment.

3. Right-Left (Lateralisation):

The brain is divided into two hemispheres, connected by the corpus callosum. Each hemisphere has specialised functions but works together to process cognitive, emotional, and motor information. The left hemisphere typically focuses on logic, language, and analytical tasks, while the right hemisphere is more involved with creativity, spatial awareness, and emotional processing.

The brain's neocortex contains four lobes (with two additional deeper lobes), each with distinct functions linked to a specific sense. It also houses motor and sensory processing areas, which include detailed representations of the body, often referred to as homunculi. These homunculi offer a fascinating map of how the brain organizes and prioritizes different body parts, placing special emphasis on regions that require fine motor skills and sensory precision.

Frontal Lobe

Location: At the front of the brain, behind the forehead.
Function: Involved in a range of complex cognitive functions:
- Decision-making: Assessing options and making judgments.
- Planning: Developing strategies and organizing actions.
- Reasoning: Logical thinking and problem-solving.
- Motor Control: Initiating and coordinating voluntary movements through the primary motor cortex.
- Executive Functions: Managing attention, inhibiting inappropriate behaviors, and regulating emotions.
- Social Behavior: Controlling social behaviors, understanding cues, and empathy.
- Personality Expression: Shaping personality traits and individuality.

Temporal Lobe (Hearing)

Location: On the sides of the brain near the temples.
Function: Responsible for auditory processing, memory, and language comprehension.

Occipital Lobe (Sight)

Location: At the back of the brain.
Function: Primarily responsible for visual processing and interpreting visual information.

Parietal Lobe (Touch)

Location: Behind the frontal lobe, at the top of the brain.
Function: Involved in sensory processing, spatial awareness, and integrating sensory information.

Primary motor cortex (Precentral Gyrus):

Location: In the frontal lobe, immediately anterior to the central sulcus.
Represents different parts of the body in terms of motor control. The size of each area reflects the precision and complexity of movements (e.g., larger areas for hands and face).

Primary Somatosensory Cortex (Postcentral Gyrus):

location: In the parietal lobe, immediately posterior to the central sulcus
Represents the sensory input from the body. Similar to the motor homunculus, larger areas correspond to regions with greater sensory acuity (e.g., lips and fingertips).

Limbic System (Limbic Lobe) (Smell)

Location: On both sides of the thalamus, including the hippocampus, amygdala, and cingulate gyrus.
Function: Crucial for emotions, memory, and motivation.

Insular cortex (Insula lobe) (Taste)

Location: Deep within the lateral sulcus, between the frontal and temporal lobes.
Function: Involved in processing emotions, self-awareness, and interoception (sensing internal bodily states). Disgust sensitivity both physical and social disgust

Basal Ganglia

Location: Deep within the cerebral hemispheres.
Function: Involved in motor control, reward processing, and cognitive functions, specifically in initiating and modulating voluntary movements.

Corpus Callosum

Location: A bundle of nerve fibers connecting the left and right hemispheres.
Function: Facilitates communication between the hemispheres and helps coordinate their functions.

Diencephalon

Location: Between the brainstem and cerebrum, consisting of the Thalamus, Hypothalamus, Epithalamus, and Subthalamus.
Function: Relays sensory information, regulates homeostasis, controls hormone secretion, and coordinates physiological processes essential for health.

Cerebellum (Proprioception)

Location: At the back of the brain, beneath the cerebrum.
Function: Coordinates voluntary movements, maintains balance, and supports motor learning.

Brain Stem

Location: At the base of the brain, connecting the cerebrum to the spinal cord (comprised of the Medulla, Pons, and Midbrain).
Function: Controls vital functions for survival, such as heart rate, breathing, and blood pressure regulation.

I found it fascinating how areas like the insula not only focus on physical sensations but also on the social dimensions of the same feelings or responses. It highlights the interconnectedness of social relationships and the physical world for humans. I believe this also occurs with the cerebellum, which is crucial not just for physical balance but also for maintaining psychological equilibrium between the brain's hemispheres.

Brain Hemispheres

This is table I have created to conceptualise the two hemispheres that I have found extremely useful.

Duality	Left Hemisphere / Yang / Masculine / Mind	Right Hemisphere / Yin / Feminine / Soul
General	Known / Order / Individual / External / IQ	Unknown / Chaos / Collective / Internal / EQ
Biochemical	Testosterone & Dopamine	Estrogen & Serotonin
Response	Sympathetic State (Readiness)	Parasympathetic state (Calm)
Operation	Conscious/Somatic Nervous System	Unconscious/Autonomic Nervous System
Awareness	Prey/Aim (Positive emotion)	Predator/Threat (Negative emotion)
Perception	Logical/Detailed “Parts”	Creative/Big Picture “Whole”
Attention	Objective/Material “Tool Based”	Tranjective/Spiritual “Purpose Based”
Action	Thinking/Intention “Decision Based”	Feeling/Intuition “Pattern Based”
Communication	Verbal & Literal	Non-Verbal & Figurative
Philosophy	Western	Eastern
Body control	Right side body control (Fine motor skills)	Left side body control (Gross motor skills)

Duality

This row explores the fundamental duality in brain function, contrasting the left hemisphere (Yang/Masculine/Mind) and right hemisphere (Yin/Feminine/Soul) through general traits.

General

Left Hemisphere: Represents the world of order and the known, dealing with structured, predictable environments. It excels in organizing, categorizing, and imposing systems to manage complexity. It prioritizes the individual perspective, focusing on self-contained entities and external realities. Associated with IQ, it thrives in solving specific, measurable problems with clear solutions, like mathematical equations or logical puzzles.
Right Hemisphere: Embodies the unknown and chaos, perceiving the world as a dynamic and interconnected whole. It is attuned to collective experiences, understanding the shared emotional and spiritual dimensions of human existence. With a focus on the internal, it processes intuition, feelings, and abstract concepts, which are hallmarks of emotional intelligence (EQ).

Biochemical

Left Hemisphere: Influenced by testosterone, promoting competitiveness, assertiveness, and focus on achieving goals. It works with dopamine, the neurotransmitter of reward, which reinforces motivation and drives action toward desired outcomes. This combination fuels ambition, exploration, and external engagement.

Right Hemisphere: Influenced by estrogen, fostering empathy, connection, and nurturing behaviors. Coupled with serotonin, which helps regulate mood and promote contentment, it creates a foundation for emotional well-being and internal harmony.

Response

Left Hemisphere: Associated with the sympathetic state, the left hemisphere prepares the body for action, focusing on readiness and external challenges. It supports the body’s fight-or-flight response.

Right Hemisphere: Associated with the parasympathetic state, the right hemisphere supports relaxation and recovery. It facilitates the body’s rest-and-digest function and fosters a state of calm.

Operation

Left Hemisphere: Functions primarily through the conscious somatic nervous system, focusing on voluntary actions and movements.

Right Hemisphere: Functions mainly through the unconscious autonomic nervous system, focusing on involuntary processes that maintain internal balance and bodily functions.

Awareness

Left Hemisphere: Attuned to prey/aim awareness, promoting positive emotions like drive, ambition, and goal-setting, linked to testosterone. It helps maintain focus on external objectives and pushes toward accomplishments.

Right Hemisphere: Aligned with predator/threat awareness, processing negative emotions such as fear, anxiety, and stress. The right hemisphere is sensitive to environmental cues and emotional resonance, ensuring awareness of potential threats or disruptions.

Perception

Left Hemisphere: Focused on logical, detailed processing, breaking down complex information into smaller, more manageable parts. This hemisphere excels in analyzing facts and working through step-by-step tasks.

Right Hemisphere: Processes information in a holistic, creative way, integrating various elements to perceive the bigger picture. It looks at the context rather than individual details, focusing on patterns and relationships.

Attention

Left Hemisphere: Directed toward material, tool-based tasks that are outcome-driven. The left hemisphere thrives in situations that require precision, analytics, and focus on measurable goals.

Right Hemisphere: Guided by transjective (beyond the objective and subjective) and spiritual focus, it emphasizes a sense of purpose and connection. The right hemisphere directs attention to broader, intangible aspects of experience, considering meaning, intuition, and holistic principles.

Action

Left Hemisphere: Driven by thinking and intention, it processes information logically and sequentially to make decision-based actions. This approach emphasizes planning, analysis, and calculated outcomes. It is quick to learn new systems and methods but slow to execute, ensuring precision and control.

Right Hemisphere: Oriented toward feeling and intuition, the right hemisphere uses pattern recognition and contextual cues to guide action. It makes decisions based on emotional resonance or instinct, rather than structured logic. This hemisphere is slower to learn due to the need for more intricate connections, it is quicker to act, favoring spontaneity and adaptability.

Communication

Left Hemisphere: Prefers verbal and literal communication, relying on explicit language and clear terms to convey ideas. This is essential for logical argumentation and factual discourse.

Right Hemisphere: Relies on non-verbal and figurative communication, including tone, body language, metaphors, and symbols. This is crucial for expressing emotions, understanding implicit meanings, and connecting with others on a deeper level.

Philosophy

Left Hemisphere: Resonates with current Western philosophy, prioritizing logic, individualism, and the pursuit of knowledge and progress. It seeks to control and optimize the external world.

Right Hemisphere: Aligns with current Eastern philosophy, which emphasizes harmony, interconnectedness, and the balance of opposites. It seeks to adapt to and flow with the natural order

Body Control

Left Hemisphere: Controls the right side of the body, specializing in fine motor skills like writing, precise movements, and detailed tasks.

Right Hemisphere: Controls the left side of the body, focusing on gross motor skills used in broader, fluid movements like dancing, sports, or spatial navigation.

THE NERVOUS SYSTEM

The key functions of the nervous system include:

1. Sensory Input: Gathering information from external stimuli (such as sight, sound, touch) and internal conditions (like temperature, stomach pain, and heart rate) and past interpretations.

2. Processing, Evaluation, and Decisions: Analysing the sensory information received in the present and past to interpret its meaning and significance to make a rational decision.

3. Motor Output: Initiating appropriate responses through voluntary or involuntary actions to maintain homeostasis, ensure safety, and enable interaction with the environment.

The different subsystems within the nervous system handle specific tasks, external & internal sensory information, voluntary & involuntary actions, and safety & survival response that is decided by the CNS (central nervous system), the brain. This is displayed by the diagram below

Central Nervous System (CNS): The Future

The CNS represents executive function and future-oriented thinking, primarily housed in the prefrontal cortex, which governs decision-making, problem-solving, and long-term planning. It acts as the top-tier controller, evaluating real-time sensory inputs from the limbic system (past) and brainstem (present) to make informed, strategic decisions. The CNS also sends motor outputs to execute those decisions, synthesizing inputs to facilitate adaptive responses.

Limbic System: The Past

The limbic system serves as the emotional and memory hub, processing past experiences to inform current decisions. Composed of structures like the amygdala, hippocampus, and cingulate gyrus, it relays emotional and introspective data to the CNS (prefrontal cortex) and brainstem. This emotional context influences the balance between sympathetic and parasympathetic activation and integrates past emotional states with present reactions, shaping the emotional responses that guide decision-making.

Peripheral Nervous System (PNS): The Present

The PNS includes all neural structures outside the CNS and limbic system, with the Thalamus as its central hub. It facilitates real-time interaction with the environment by processing and relaying sensory and motor information between the limbic system and CNS, operating both consciously and unconsciously. The PNS regulates goal-directed (aim) and protective (threat) responses through sympathetic and parasympathetic states, functioning along a dynamic spectrum. Additionally, it governs the somatic and autonomic nervous systems, ensuring seamless coordination between voluntary and involuntary actions.

Sympathetic State - Activation (State of Readiness):
- Engaged when the body perceives a challenge or stress.
- Prepares the body for action: increased heart rate, heightened alertness, redirected blood flow.
Parasympathetic State - Relaxation (State of Calm):
- Engaged when the body perceives safety and calm.
- Supports recovery: reduced heart rate, digestion, energy conservation, preparing the body for future action via CNS feedback.

Somatic Nervous System: Voluntary, Conscious, Exteroceptive

The somatic nervous system governs conscious motor control and the processing of external sensory information. It manages the voluntary movement of skeletal muscles and sensations from the skin, as well as regions involved in movement, such as the face and neck. Through communication with the brainstem via the spinal cord, sensory data is relayed to the thalamus for further processing and coordination. This system enables deliberate actions and a heightened perception of the external environment, making it essential for voluntary interaction with the world.

Autonomic Nervous System: Involuntary, Unconscious, Interoceptive

The autonomic nervous system regulates involuntary processes and the functions of internal organs. It oversees critical operations such as digestion, heart rate, respiratory rate, and hormonal balance, connecting with the brain's central hub (thalamus) via pathways like the Vagus nerve. This system plays a vital role in maintaining homeostasis by balancing internal bodily systems to respond effectively to both internal needs and external environmental changes.

CONCLUSION

The human nervous system is a highly intricate network that orchestrates the functions of all other systems within the body. At its core, the brain serves as the central control unit, integrating sensory input, processing information, and making decisions to guide appropriate responses. Its complexity is amplified by the dynamic interplay between different regions and hemispheres, each contributing unique strengths. The left hemisphere, associated with logic, detail, and conscious control, operates in harmony with the right hemisphere, which processes emotions, intuition, and the broader context. Together, they form a cohesive system, constantly working in unison.

These dualities are reflected in the balance between sympathetic and parasympathetic states, enabling adaptability in the face of environmental challenges or moments of peace. This integrated system ensures homeostasis, survival, and optimal functioning, relying on the cooperative efforts of the central and peripheral nervous systems to maintain harmony between internal processes and external demands.

The nervous system’s ability to integrate and respond to both past experiences and present circumstances is essential to human behavior, cognition, and physical action. It guides us toward the best possible outcomes for both survival and well-being, adapting dynamically to the demands of life. Over time, these adaptations shape and reflect who we are in our unique personalities.

Note: Please keep in mind that the diagrams and explanations provided in this post are conceptual tools designed to simplify complex ideas. While they aim to offer a practical understanding of these topics, they may not always align with established scientific facts. Future posts will explore practical applications based on these concepts.

MICHAEL FARAH