Transcription
Hello and welcome to this first video of our Neuroscience training. Neuroscience is a fascinating field focusing on the organization and function of the nervous system. It's a vast domain encompassing medicine, psychology, and biology.
In this training, we will primarily focus on cognitive Neuroscience, which has immediate and concrete applications. In this first module, we will look at the nervous system. Let's start by studying its anatomy.
The nervous system controls the entire body through nerve impulses. It consists of two parts: the central nervous system and the peripheral nervous system. The role of the central nervous system is to process information. It is composed of the brain, the cerebellum, the brain stem (which includes the midbrain, the pons, and the medulla oblongata, formerly known as the bulb), and the spinal cord. The cerebellum, brain, and brain stem form a unit called the encephalon. The encephalon is housed in the skull. The spinal cord, on the other hand, is housed in the vertebral canal, the space between the vertebrae.
We usually refer to the brain to describe the whole, but in reality, the brain, which acts like the human hard drive, represents only a part of the encephalon. The encephalon has various roles, notably the management of all intentional behaviors: sleep, thought, language, project or event planning, decision making, learning, etc.
The brain itself is divided into two hemispheres: the right hemisphere, which is more intuitive and emotional with an artistic sensitivity, and the left hemisphere, which is involved with memory and symbolic thinking. The left brain is also the seat of logic and reasoning. Each hemisphere is divided into several lobes, as you can see in your PDF support: the parietal, occipital, frontal, temporal, limbic lobes, and the insular cortex.
Extending from the brain, the spinal cord is a bundle of nerve cells whose main function is to transmit nerve impulses from the cerebral cortex to the peripheral nerves and from effector organs such as the skin and muscles to the brain. The spinal cord extends almost the entire length of the vertebral column and is 1 cm in diameter. It supports the 31 pairs of spinal nerves, which themselves are part of the peripheral nervous system.
The peripheral nervous system is composed of all the cranial and spinal nerves, as well as neural ganglia. It is divided into two parts: one, the autonomic nervous system, itself composed of the parasympathetic system, which manages involuntary activities of the body at rest (digestion, heart rate, blood pressure, and respiration), and the sympathetic nervous system, which is mainly active when the body is awake or stressed; two, the somatic nervous system, which links the central nervous system to the body's environment through various types of nerve fibers, including motor and sensory fibers. There are two types of somatic nerves: the 12 cranial nerves, they are either sensory or motor; the nine spinal nerves, arranged in five major groups along the spinal cord.
Now let's discuss neurons. The neuron, the basic unit of the nervous system, emits and propagates nerve signals through proteins regulating ion channels. Neurons also secrete neurotransmitters to transmit nerve impulses. Neurons differ from other cells due to their remarkable longevity. However, they are very fragile, and an impact can have irreversible consequences. Their other specificity is the unmatched speed at which their metabolism functions, requiring a high supply of oxygen and glucose. They are constantly traversed by electrical signals.
A neuron is composed of three parts: its cell body, its axon, which acts like a tail propagating the nerve impulse to other cells, and its dendrites, which are like small branches allowing the neuron to connect with other neurons. But nerve impulses are not transmitted only by neurons. Neurotransmitters, which are the brain's chemical messengers, also play a significant role. There are four categories of classic neurotransmitters: one, monoamines, derived from an amino acid, such as serotonin, which is produced from tryptophan; two, endorphins; three, amino acids; four, other chemical substances, such as adenosine or acetylcholine.
Finally, when there is an area where information passes between two cells, it is called a synapse: either an electrical synapse, as seen with neurons, or a chemical synapse, as seen with neurotransmitters.
Let's conclude this first video with the concept of brain plasticity. Plasticity, also known as neuroplasticity, is the brain's ability to adapt to the environmental conditions it is subjected to. The more new information we receive, the more synapses we create, and the more we adapt and learn. Learn from birth. However, neuroplasticity is not only related to the increase in the neural network but also to the elimination of obsolete connections.
It is possible to easily increase brain plasticity, for example, through artistic and creative activities, but also through sports and manual activities. Neuroplasticity varies from person to person, depending on age and environment. However, it should not be believed that a secure and peaceful environment fosters this development. The brain sometimes needs to enhance its neural network to acquire additional faculties necessary for the individual's survival.
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