What’s the point of neurotransmitters, and why not just have a long neuron?

Tim Chiswell has an interesting answer, but it doesn’t technically address this question.

Neurotransmitters likely evolved because of long neurons, not in spite of them. A long neuron is a useful tool, but it’s just a cellular extension that doesn’t do much by itself. It is the neurotransmitters that actually communicate information from that long neuron to its downstream targets (i.e. the dendrites of other neurons).

There are several reasons why you can’t just have a “direct” connection between two cells, including poor conduction, lack of signal regulation, and (as Tim talked about) just plain inefficiency.

Neurotransmitters are short distance communication molecules—they don’t work over distances much longer than a few Nano-meters, because neurons and glia clean them up very quickly.

Hormones, on the other hand, can circulate through the bloodstream and effect many targets throughout a wide area. But they are entirely uncontrolled. You couldn’t signal to a specific cell with a hormone.

Therefore, neurotransmitters evolved to facilitate long-distance communication through very short-distance, precision signalling.

Neurotransmitter release happens at synapses, which are tiny tiny gaps between axons and dendrites.

Any neurotransmitter that leaks out beyond the synaptic cleft gets recycled back into cells.

Long story short, neurotransmitters exist because of the extreme length of axons.

Reference: Ben Callif

Why is Einstein's brain still kept in the museum?

When Albert Einstein was born, his head was unusually large compared to other normal children. At that time, medical science was not much developed so the reason for the aforementioned big head remains unknown.

The circumstances with Einstein were such that he was considered an abnormal child as similar Hritik Roshan in Hindi Movie named Koi Mil Gya. Einstein was a very shy child and he did not speak a single word even at age four. At age nine, Mr. Einstein started speaking properly.

It is a world known that Einstein was counted among stupid children in school life. Especially Einstein's teachers did not like him at all, because he used to fail in every subject other than mathematics and science. And even the teacher's scold did not have any effect on him. Wow, I am not only who ignore teacher’s scold

Once, his mathematics professor called him a lazy dog. It is said that in childhood he was also weak in mathematics and the teacher refused to teach him mathematics. Then his mother started teaching him at home and there was such interest in mathematics that he became a great mathematician.

Now Back to the Question

After Einstein's death, the pathologist Dr. Thomas Stoltz Harvey took his brain apart from his skull without the consent of his family. (It was unbelievable at that time)

Despite the hospital's request he did not return it and kept it for around 20 years. After 20 years, and with the permission of Hans Albert ( Einstein's son), he started studying over Einstein’s brain. Readers definitely would be Surprise to know that Einstein's brain was sent to different scientists by making 200 pieces of the brain. (200 piece of an Einstein's brain, isn't it amazing)

Pathologist Dr. Thomas was also fired from the hospital for this madness. But doctors' efforts didn't get wasted. In the same study, they found that Einstein had an extraordinary cell structure in the mind as a comparison to the brains of ordinary people. That is why Einstein's brain was very extraordinary. Einstein's eyes are kept in a box.

Again you will be surprised to know that Einstein's eyes are also kept safe.

Mutar Museum (Museum in Philadelphia) is one of the only places in the world where you can see Albert Einstein's brain fragments. Brain section, stained with 20 μm thick and cassyle violet, is preserved in the glass slide on display in the main museum gallery.

As we are reading Einstein, better to know some other random facts.

Einstein was supposedly slow to talk

Einstein's peculiar habits were never to wear socks. For Einstein, socks were a pain because they often used to get holes in them.

Einstein loved to smoke

Einstein was asked to become the President of Zionist Israel in 1952 but he declined the offer.

Einstein loved sailing and violin.

Einstein later regretted his involvement in the development of the atomic bomb by sharing theory of a uranium fission bomb and his famous formula, E=mc² to U.S. President Franklin D. Roosevelt.

Reference: Ashish Pandey

What actually happens to an impulse after reaching the brain?

The photons of the light which fall on the object are reflected by it and are incident on the retina. The retina senses the frequency and wavelengths of these photons. The retina can sense the wavelength between 400–700 Nano-meters.

Just to give a quick comparison, if electromagnetic waves belonging to various ranges of wavelength are compared to the distance from Kanyakumari to Leh in the Himalayas, the range that is perceived by the human retina (400–700 nm) is equivalent to the size of a room. We can now imagine how insignificant little of the existing universe we actually perceive!

The rods and cones are stimulated by photons and a chemical signal is released. The chemical signal is converted into an electrical signal which becomes a brain wave inside the brain. The brain wave is indeed an electrical wave created by the action of neurons.

A million dollar question is, who reads these brain waves, how they are read, and what is the reason behind this reading.

Nobody knows the answer.

Similarly, the electrical signals generated by the neurons after sound input will also become waves in the brain.

All five sensory inputs become electrical signals and they become waves in the brain. Of course, there are filters on their way to their final destinations.

The function of the brain is to create electrical waves by the neurons of the brain. Different patterns of electrical waves are created and the neurons group together to generate particular types of waves. They are also stored as memories. Whenever a new pattern of wave is generated, it is immediately cross matched with the memorized bits of information and the actual meaning of that input is deciphered.

It all depends on what type of waves we have stored as memory. Any fresh input is observed and understood with the bias of previous existing memory. It is like wearing red glass spectacles and looking at the world!

We actually do not know what this external world really looks like! Our brain works on its matching proficiency and describes the external world according to its memorized data. The external world looks different for a nocturnal bat, a cat, a dog, or any other animal. The world is read differently by different animals depending upon the design of their brain!

Reference: RN Sreenathan

What are some of the most unusual brains?

The brain of Kim Peek, the real-life 'savant' on whom Dustin Hoffman's character in the film Rain Man is based, was truly an unusual one.

Peek was born in with macrocephaly (large cranium), damage to the cerebellum (related to motor skills), and agenesis of the corpus callosum, a condition in which the bundle of nerves that connects the two hemispheres of the brain is missing, secondary connectors such as the commissure and the hippocampal commissure were also missing.

His brain was studied by NASA scientists in the hope of explaining his outstanding mental capacities. Peek is called a "mega-savant" because he was a genius in about 15 different subjects, from history and literature and geography to numbers, sports, music and dates.

He could speed through a book in about an hour and remember almost everything he had read, memorizing vast amounts of information. Peek read by scanning the left page with his left eye, then the right page with his right eye, a skill neuroscientists believe is related to the lack of hemisphere connection. According to an article in The Times newspaper, he could accurately recall the contents of at least 12,000 books. He apparently had developed language areas in both hemispheres. Among his most impressive feats was his ability to provide traveling directions between any two cities in the world.

Peek did not walk until he was four years old and had difficulty with other ordinary motor skills, presumably due to his damaged cerebellum, which normally coordinates motor activities. Despite his phenomenal memory and arithmetic abilities, his IQ was only 87.

Agenesis of the corpus callosum is a fairly rare neurological condition. Individuals without an intact corpus callosum sometimes experience linguistic and social impairments. It’s generally believed that the left hemisphere is responsible for linguistic understanding, and the right hemisphere provides the emotional context and subtlety. The main linguistic and social problems stem from difficulties understanding non-literal language, including idioms, proverbs, irony, sarcasm, subtle jokes and conversational implicatures.

Sometimes a split-brain surgery is performed on epilepsy patients to prevent the spread of seizures. In these patients, the right hemisphere, which controls the left hand and foot, acts independently of the left hemisphere and the person’s ability to make rational decisions. This can give rise to a kind of split personality, in which the left hemisphere gives orders that reflect the person’s rational goals, whereas the right hemisphere issues conflicting demands that reveal hidden desires. These fascinating stories are recounted in Michael Gazzaniga and Oliver Sacks’s numerous books.

Reference: Huyen Nguyen

What is deep brain stimulation for Parkinson's Disease?

Deep brain stimulation is a surgical technique to treat the symptoms of Parkinson’s disease such as tremor, rigidity, stiffness, slowed movement and difficulty in walking. The procedure is performed on those who have not benefited from medications.

The deep brain stimulation system has three components:

• The lead, also known as an electrode that is inserted inside the skull through a small opening and is implanted in the targeted area of the brain.
• The extension is a wire that connects the lead to the neurostimulator. It is passed under the skin of the head, neck and shoulder.
• The neurostimulator is implanted under the skin of the collarbone. Other places where it is implanted are lower chest and under the skin over the abdomen.

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What is the procedure of deep brain stimulation

•  A  medical device known as neurostimulator is used. The device is battery operated and is similar to a pacemaker. The size of the stimulator is similar to that of a stopwatch.
•   The device is implanted in the brain to deliver electrical stimulation to targeted areas that control movement and blocks the abnormal nerve signals that cause Parkinson’s disease symptoms.
•  MRI and CT Scans are performed to locate the exact place in the brain from where the electric nerve signals generate the PD symptoms.
•  Microelectrode recordings are also used by some surgeons to identify with precision the targeted location in the brain that has to be stimulated.
•  Generally there are three common target locations in the brain:
•  Thalamus
•   Subthalmic nucleus
•   A portion of the Globus Pallidus
• After the implant is placed, electrical impulses are sent from the neurostimulator through the extension wire, into the brain that blocks the abnormal electrical signals of the brain.

Reference: Nitish Chitkara

Which type of neuron is absent in the peripheral nervous system?

The peripheral nervous system contains afferent sensory neurons that propagate action potentials to the CNS via electrochemical junctures called synapses, using Neuro transmitters as chemical messengers.

The peripheral nervous system also contains efferent motor neurones that propagate action potentials away from the CNS towards effectors (skeletal muscle, smooth muscle, cardiac muscle, and glands) to stimulate them and induce a response. Skeletal muscles are stimulated via the somatic nervous system, whereas cardiac muscle, smooth muscle and glands are stimulated via the autonomic nervous system. The somatic and autonomic nervous system are the two subdivisions of the peripheral nervous system.

The peripheral nervous system does not contain relay neurones, which reside in the central nervous system (brain, spinal cord, and retina) and transfer electrical information that has entered from the sensory neurons of the dorsal root ganglia to the motor neurones of the ventral route ganglia so that the effectors can be stimulated.

The peripheral nervous system also contains the various dogiel cells (multipolar neurones) and supporting cells (similar to astrocytes in the brain) of the enteric nervous system.

Reference: Charlie Phaure

What are the main major symptoms of brain tumors?

Tumors in any part of the brain may cause the pressure inside the skull (known as intracranial pressure) to rise. This can be caused by growth of the tumor itself, swelling in the brain, or blockage of the flow of cerebrospinal fluid (CSF). Increased pressure can lead to general symptoms such as:

1. Headache
2. Nausea
3. Vomiting
4.  Blurred vision
5.   Balance problems
6.   Personality or behaviour changes
7.   Seizures
8.   Drowsiness or even coma

Headaches that tend to get worse over time are a common symptom of brain tumors, occurring in about half of patients. (Of course, most headaches are not caused by tumors.)

As many as half of people with brain tumors will have seizures at some point. The type of seizure may depend on where the tumor is. Sometimes this is the first sign of a brain tumor, but fewer than 1 in 10 first seizures are caused by brain tumors.

Symptoms of tumors in different parts of the central nervous system

Brain and spinal cord tumors often cause problems with the specific functions of the region they develop in. But these symptoms can be caused by any disease in that particular location — they do not always mean a person has a brain or spinal cord tumor.

1.          Tumors in the parts of the cerebrum (the large, outer part of the brain) that control movement or sensation can cause weakness or numbness of part of the body, often on just one side.
2.         Tumors in or near the parts of the cerebrum responsible for language can cause problems with speech or even understanding words.
3.     Tumors in the front part of the cerebrum can sometimes affect thinking, personality, and language.
4.          Tumors in an area of the brain called the basal ganglia typically cause abnormal movements and an abnormal positioning of the body.
5.          If the tumor is in the cerebellum, which controls coordination, a person might have trouble with walking or other everyday functions, even eating.
6.         Tumors in the back part of the cerebrum, or around the pituitary gland, the optic nerve, or certain other cranial nerves can cause vision problems.
7.          Tumors in or near other cranial nerves might lead to loss of hearing, balance problems, weakness of some facial muscles, or trouble swallowing.
8.          Spinal cord tumors can cause numbness, weakness, or lack of coordination in the arms and/or legs (usually on both sides of the body), as well as bladder or bowel problems.
9.          The brain also controls functions of some other organs, including hormone production, so brain tumors can also cause many other symptoms that aren’t listed here.

Having one or more of the symptoms above does not mean that you definitely have a brain or spinal cord tumor. All of these symptoms can have other causes. Still, if you have any of these symptoms, especially if they don’t go away or get worse over time, see your doctor so that the cause can be found and treated, if needed.

Reference: Jonser Emmash