NeuroExplorer

Paul Broca is one of the most influential neuroscientists best known for his patient, Tan. Well, his name wasn't really Tan. His name was Louis Victor Leborgne, and his incredibly unusual neurological disorder settled a debate about the location of language capabilities in the brain. In 1861, Leborgne approached Broca at the Bicetre Hospital to receive surgery for a leg infection. Leborgne had suffered from several medical conditions prior to his surgery; he had epilepsy at a young age and subsequently lost his ability to produce fluent speech. It was Leborgne's language disorder that really caught Broca's attention. Leborgne could think properly, but whenever he tried to communicate with Broca and verbalize his thoughts, all that came out of his mouth was the meaningless word "tan." For this reason, many scholars of neuroscience simply refer to Leborgne as "Tan". Broca realized that he could learn about our language capabilities by studying Leborg...

Take a look at the image above. This is the chemical structure of caffeine, a widely consumed chemical that you are probably familiar with (it's in your coffee). Scientists use this as a shorthand depiction of chemical structures. While this image may be confusing at first, it's actually very simple to understand once you know the rules! And there are only two! The first rule is carbon at the corners . What does this mean? Well, at every corner where you do not see a letter (an atom), there is an implied carbon. This shorthand notation allows us to show the structure without writing in each single carbon. There is also an implied carbon at the end of every line. Using this rule, let's place carbons at the corners and the ends of the lines. Now that we have the carbons in place, let's move to the next rule: hydrogens bonded to carbons are implied.   To understand this rule, we must first understand the bonding properties of carbon. Carbon likes to make fou...

Let's zoom into the synapse that makes neurotransmission possible. Action potentials travel in the direction from the dendrite to the axon. Therefore, in order to transmit signals from one neuron to another, the signal must leave the axon of one neuron and cross the synaptic cleft to reach the receiving dendrite of another neuron. The neuron that delivers the signal is known as the presynaptic neuron , as shown in the image below. The neuron receiving the signal is known as the postsynaptic neuron . The gap between both neurons is the synaptic cleft. Now, don't confuse the terms "synapse" and "synaptic cleft". The synapse includes the presynaptic neuron, the postsynaptic neuron, and the gap in between. The gap is known as the synaptic cleft . Electrical signals travel as action potentials through the axon. When they reach the axon terminal , which is the very end of the axon, neurotransmitters are released into the synaptic cleft. The neurotran...

As we learned about in the blog post about the  Brain Box , the brain is protected by the skull, meninges, and cerebrospinal fluid (CSF). The meninges, which sit below the skull and vertebral column, is a series of three membranes that surround the brain and spinal cord. Its function is to protect and support the brain and spinal cord and contain cerebrospinal fluid (CSF). The three layers of the meninges (from outermost to innermost) are the dura mater, arachnoid mater and pia mater. The dura mater  is a thick, tough layer that adheres to the skull on one side and the arachnoid mater on the other. It is an extra protective layer that attaches the brain to the skull and the spinal cord to the vertebral column. Beneath the dura mater is the arachnoid mater. The arachnoid mater  is named after its appearance that resembles a cobweb. It is made of strands of connective tissue, known as arachnoid trabeculae , that suspend the brain in place. Between the arachno...

The ventricles are cavities throughout the brain that produce and distribute cerebrospinal fluid. Cerebrospinal fluid (CSF) is a clear, colorless fluid that suspends the brain and protects it from strain. Check out this blog post to learn more about cerebrospinal fluid. The ventricles are lined with the choroid plexus , a membrane made of ependymal cells (a glial cell) that secrete CSF. There are four ventricles in the human brain. There are two C-shaped lateral ventricles ; one in each of the hemispheres. The lateral ventricles connect to the third ventricle via an opening known as the interventricular foramen . The third ventricle , which resembles a misshapen donut, is located along the midline of the diencephalon. It connects to the fourth ventricle via the cerebral aqueduct. The fourth ventricle is located between the cerebellum and brainstem. It has three openings that allow the CSF to enter the subarachnoid space (remember the meninges). Therefore, the CSF leaves the ...

Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less. — Marie Curie Physicist

We are just an advanced breed of monkeys on a minor planet of a very average star. But we can understand the Universe. That makes us something very special. — Stephen Hawking Physicist

Cells require many substances to ensure proper function — nutrients, oxygen, and more. But how does the cell acquire these substances? In other words, how are these substances transported? There are two main ways particles can be transported: active and passive transport. What is the difference? Well, to understand these two terms, we must first understand the ideas of particle concentrations and concentration gradients. The concentration of particles is simply the number of particles in that area. A gradient is uneven distribution, or concentration, of particles. Now, back to transport. Passive transport is the movement of particles without  energy. Particles move from a high to low concentration  along the concentration gradient. Active transport, however, is the movement of particles with  energy. The particles move from a low to high concentration   against the concentration gradient. Why does active transport require energy? Well, the cell prefers to be in...

To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge. — Nicolaus Copernicus Astronomer

As neuronal signals are constantly fired by the brain, they produce rhythmic electrical patterns known as brain waves that can be detected through a monitoring method known as electroencephalography (EEG). Electroencephalography is a noninvasive process during which electrodes (small metal conductors) placed on the scalp detect the brain waves. The EEG machine then amplifies and records the signals in a wave pattern. The human brain produces four types of brain waves that each create distinguishable shapes on EEG readings: alpha waves, beta waves, theta waves and delta waves. Alpha and beta waves are produced by the awake brain. Alpha waves, with frequencies of 8 to 13 Hz, originate mainly in the parietal and occipital lobes of the brain when the eyes are closed and the brain is relaxed. Beta waves are faster, with frequencies of 14 to 30 Hz, and originate in the frontal and parietal lobes when you are processing a sensory input or focusing on a task. Theta and delta waves are prod...

Imagination will often carry us to worlds that never were. But without it we go nowhere. — Carl Sagan Astronomer  

The eyes are your windows to the external world. You are surrounded by different types of energy and molecules that must be translated into perceptions through a network of cells, fibers and electrical signals. Let's take a journey through the eye. In order to understand how vision works, we must first understand what light is. Light is an electromagnetic (EM) wave made of oscillating electric and magnetic fields. EM waves are able to travel without a medium, which is why light is able to travel to Earth through the vacuum of space. However, it is only a sliver of the entire electromagnetic spectrum (pictured below). The light that we are familiar with is visible light. However, there are also radio waves, microwaves, infrared light, ultraviolet light, X-rays and gamma rays  —  and all of them are invisible to us! This is because the human eye can only detect wavelengths from 400 to 700 nanometers (visible light). Visible light itself has a range of wavelengths that deter...

The human nervous system is a complex and fascinating structure whose capabilities are far-reaching. How surprising is it that we know so much more about stars billions of light years away than our own brains? Why is the brain so mysterious? Well, studying the brain is a significant challenge. First of all, we cannot simply open the skull and observe the living brain, for obvious reasons. Second, the brain's many functions are at the molecular level, making them impossible to observe, even with the world's most powerful microscopes. According to the World Health Organization,  "N eurological disorders, ranging from epilepsy to Alzheimer disease, from stroke to headache, affect up to one billion people worldwide. An estimated 6.8 million people die every year as a result of neurological disorders."  Therefore, understanding the human brain is crucial.

The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. — Albert Einstein Physicist

Happiness can be found, even in the darkest of times, if one only remembers to turn on the light. — J.K. Rowling Author  

When you picture the brain, what do you see? Most of the brain is the cerebrum, which controls higher functions like thinking and speaking. The cerebrum is split down the middle by the longitudinal fissure (the red line in the picture) into the left and right hemispheres. These two halves are able to communicate through a bridge of nerve fibers known as the corpus callosum. Each half of the cerebrum is divided into four lobes: the frontal lobe, the temporal lobe, the parietal lobe and the occipital lobe. Therefore, the brain has eight lobes all together. Each lobe is associated with different functions. The top layer of the brain's wrinkly surface is the cortex. The cortex not only covers the surface of the brain but also the space between the hemispheres. The part of the cortex that covers the cerebrum is known as the cerebral cortex. The cortex is gray matter, which consists of unmyelinated axons, dendrites, cell bodies and glial cells. However, the gray matter act...

Let's take a look at a cell. One thing that you will find common among all cells is the cell membrane - whether it's an animal cell, a plant cell or a bacterial cell. While this layer may only be ten nanometers thick, it has an intricate molecular structure designed for efficient transport of material into and out of the cell. This property is known as selective permeability , the control of the passage of materials across the cell membrane. The cell membrane is designed in a way that substances having certain properties are unable to enter or leave the cell (this movement across the cell boundary is known as transport ). The fluid mosaic model  describes how substances, mainly cholesterol, phospholipids and proteins, slide freely in the membrane. First, let's start with the phospholipid bilayer . A phospholipid a complex lipid with a "head" and a "tail". The head is made of one polar/hydrophilic phosphate group and a glycerol molecule. The ta...

Life is like riding a bicycle. To keep your balance you must keep moving. —  Albert Einstein Physicist

The 3-pound mass of jelly sitting in between our ears is extremely  delicate. It lacks cartilage or bone to hold it together, and it isn't made of muscle tissue. To ensure its safety, the brain is enclosed within a thick, bony structure - the skull . Throughout your life, you will bump your head several times, but your brain will stay unharmed; the skull's purpose is to protect the brain. The cranium is the part of the skull enclosing the brain, but not including the face or jaws. The cranium is comprised of eight flat bones connected at sutures (immovable joints). These plate-like bones grow over time. A baby's skull is extremely fragile; you can even feel the sutures on a baby's head. The soft spot at the top of the head is where the sutures all meet. Eventually, this spot closes over and the cranium is sealed shut. In addition to the cranium, the fourteen facial bones also make up the skull. If you were to remove the skull (and doctors are able to do this...

On September 13th of 1848, railroad worker Phineas Gage was working on a railroad construction project, tamping gunpowder into a blasting hole with an iron rod. Unfortunately, the gunpowder exploded, shooting the rod skyward. It penetrated Gage's left cheek, ripped into his brain, and exited through the back of his skull! Surprisingly, Gage walked away, fully conscious, and described what happened to the doctor. The accident left him blind in the left eye. But that wasn't the only consequence; people began to describe Gage as irritated and aggressive. He was no longer mild-mannered and soft-spoken; his personality had completely changed. Phineas later moved from the United States and died after a series of seizures at age 36. Phineas' odd case is a great yet extreme example of how functions of the brain are localized, and how this manifests itself through psychological behaviors. Today, Phineas Gage's skull and the tamping iron are on display at the Warr...

The cell theory is a universally accepted principle of biology that sets the relationships between cell and livings things. The cell theory is composed of three basic principles that were established by three 19th-century German scientists – Matthias Schleiden, Theodor Schwann and Rudolph Virchow. The first principle of the cell theory is that all life is made of cells . All living organisms in the six kingdoms of life are made of cells. However, not all cells are alike. There are two categories of cells - prokaryotic and eukaryotic. Prokaryotic cells are simpler and lack a membrane-bound nucleus. In contrast, eukaryotes are larger and highly complex with a defined nucleus and several membrane-bound organelles. The second principle of the cell theory is that the cell is the basic unit of life . Some simpler organisms may by unicellular, meaning they only have one cell. However, these unicellular organisms still have remarkably complex structures – inside each cell are atoms...

Neurons can transmit signals at astonishing speeds - some signals can travel as fast at 268 miles per hour! How are neurons capable of such speeds? Well, their axons, which transmit signals to other neurons, have a special covering known as the myelin sheath. Myelin, a lipid-rich substance, insulates the axon and increases the speed of signal transmission. As an action potential travels down the axon, some ions may cross the membrane and exit the cell. However, the presence of myelin prevents this escape. In the peripheral nervous system, myelin is found in the membranes of Schwann cells, a type of glial cell. Each Schwann cell forms one unit of myelin. In the central nervous system, oligodendrocytes, another type of glial cell, tightly wrap around the axon to form several layers of insulation. Each process of an oligodendrocyte can form one segment of myelin for several different cells. Myelin is not the only special feature of neurons that accelerates signal speeds. There are...

You may be familiar with the branched out structure of the neuron - multiple, short dendrites and one long axon. But did you know that there are actually other neuron structures that differ in the number of processes? Processes are the project parts of an organic structure - in the case of the neuron, they are the dendrites and the axon. You are probably most familiar with the multipolar neuron , which has at least three processes extending from the soma - one axon and two or more dendrites. Multipolar neurons are the most abundant type of neurons and are usually motor neurons and interneurons. But did you know there are two other structures? Take a look at the picture below: The bipolar neurons  have two processes - one axon and one dendrite - that extend from opposite sides of the cell body. Bipolar neurons are rare and are only found in sensory organs - for example, the retina of the eye. Unipolar neurons  are sensory neurons that have one process extending from the...

Neurons are highly specialized cells that respond to stimuli and transmit electrical and chemical signals to parts of the body. Their structure makes their function tremendously efficient. Take a look at the image below: Notice the branched out processes (projections). These processes, known as dendrites, receive electrical signals and transmit these signals down to the soma (cell body) and then the axon. Remember, electrical signals always travel from the dendrite end to the axon end . The soma contains organelles common to any other cell: the DNA-containing nucleus, cytoplasm, mitochondria, ribosomes, the endoplasmic reticulum, the Golgi Apparatus - just to name a few. Once the electrical signal is carried across the soma, it travels along the axon, a long fiber-like extension that transmits these impulses away from the cell body to other cells. The axon is covered in the myelin sheath, a special insulating envelope that increases the speed of signal transmissio...

Did you know that there are actually three types of neurons - each corresponding to the three major functions of the nervous system? These major functions are sensory input, integration and motor output. What's the difference? The sensory input is carried out by sensory (afferent) neurons that detect a stimuli. Signals are then sent to the brain and spinal cord to be processed in the second stage known as integration. Integration is carried out by interneurons in the brain and spinal cord that interpret the messages from sensory neurons. After processing the input, interneurons relay the message to body parts, where a response is produced at the effector organ in the third and final stage known as the motor output. The motor output is carried out by motor (efferent) neurons that receive messages from interneurons and then activate certain body parts to respond to the stimuli. Afferent? Efferent? They sound so similar! A trick to remember the difference between the two is to loo...

When you hear the term "brain cells", what first comes to mind? Neurons, of course! Well, turns out there are so many other types of cells in your nervous system that have critical roles. Which ones, you ask? NEUROGLIA! The little heroes of the nervous system! Of course, neurons play a crucial role in the nervous system. But the functions carried out by the nervous system could not  be achieved without neuroglia. The glial cells provide support, nutrition insulation and help with signal transmission. In the central nervous system, the four main types of glial cells are the astrocytes, microglia, ependymal cells and oligodendrocytes. Astrocytes  come from Greek for "star cell", given the name for its star-shaped appearance underneath a microscope. Astrocytes form the cellular glial scars , control the release of ions, form the blood-brain barrier and clear out neurotransmitters from the synapses. Microglia  ("small glue") are specialized macrophages...

The Nervous System Central Nervous System (CNS) consists of the brain and spinal cord the main control center Peripheral Nervous System (PNS) consists of the nerves branching off from the brain and spinal cord allows the CNS to communicate with the rest of the body consists of the sensory division and the motor division Peripheral Nervous System Sensory Division also known as the afferent division picks up sensory stimuli transmits signals from the body to the brain Motor Division also known as the efferent division sends directions from the brain to effector organs and glands transmits signals from the brain to the body consists of the somatic and autonomic nervous system Motor Division Somatic Nervous System voluntary ⇒ skeletal muscle movement Autonomic Nervous System involuntary ⇒ internal organs example: heartbeat, lungs, stomach consists of the sympathetic and parasympathetic nervous system Autonomic Nervous System Sympathe...

The human brain possesses amazing capabilities that make it the most amazing and powerful organ in the body. That is, when it's functioning properly. When it's not the effects can be devastating. Take a look at the diagram below (1) : The brain on the left side is normal, and the brain on the right has severe Alzheimer's (a neurodegenerative disease). Notice how the brain shrinks . The small seahorse-shaped hippocampus in the medial temporal lobe is crippled, thus losing the ability to store memories. But... how does this all happen? It all starts in the wrinkled cerebral cortex, where action potentials travel across the synapses of the billions of neurons in the brain. Chemical neurotransmitters jump across these synapses and carry the signals to other neurons (pictured below)(2) . The brain is functioning properly. However, in patients with Alzheimer's disease, proteins known as Beta-Amyloid begin to clump together and important Tau proteins begin to fall ap...

Welcome to my blog! My goal is to share my excitement for the brain with you! I hope that, within time, you share this same fascination with me and realize that the human nervous system is a complex and fascinating structure whose capabilities are far-reaching. We still have only uncovered very little of the brain's secrets! I hope that, as we progress through this blog, we will  uncover more secrets about our fascinating nervous system that makes us who we are. Enjoy!

Hello! This is the beginning of my journey in neuroscience. Buckle up and enjoy!