The human brain has an estimated storage capacity of 256 exabytes (or 256 billion gigs), the equivalent of 1.2 billion average PC hard drives, enough CDs to make a stack which would reach beyond the moon and 15 libraries for every person on the planet.
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have one, even if diffuse neural tissue is present. It is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell.
The brain of a vertebrate is the most complex organ of its body. In a typical human the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons,[1] each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.Physiologically, the function of the brain is to exert centralized control over the other organs of the body.
The brain acts on the rest of the body both by generating patterns of muscle activity and by driving secretion of chemicals called hormones. This centralized control allows rapid and coordinated responses to changes in the environment. Some basic types of responsiveness such as reflexes can be mediated by the spinal cord or peripheral ganglia, but sophisticated purposeful control of behavior based on complex sensory inputrequires the information-integrating capabilities of a centralized brain.
From a philosophical point of view, what makes the brain special in comparison to other organs is that it forms the physical structure that generates the mind. As Hippocrates put it: "Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations."[2] Through much of history, the mind was thought to be separate from the brain. Even for present-day neuroscience, the mechanisms by which brain activity gives rise to consciousness and thought remain very challenging to understand: despite rapid scientific progress, much about how the brain works remains a mystery. The operations of individual brain cells are now understood in considerable detail, but the way they cooperate in ensembles of millions has been very difficult to decipher. The most promisingapproaches treat the brain as a biological computer, very different in mechanism from electronic computers, but similar in the sense that it acquires information from the surrounding world, stores it, and processes it in a variety of ways.
This article compares the properties of brains across the entire range of animal species, with the greatest attention to vertebrates. It deals with the human brain in so far as it shares the properties of other brains.
The ways in which the human brain differs from other brains are covered in the human brain article. Several topics that might be covered here are instead covered there because much more can be said about them in a human context. The most important is brain disease and the effects of brain damage, covered in the human brain article because the most common diseases of the human brain either do not show up in other species, or else manifest themselves in different ways.
Among the changes that occur in the body when children hit puberty, there is a slightly reduced communication time between neurons. "If you don't get rid of the noise or less useful information, it is a problem," said Tsien. While each neuron averages 3,000 synapses, their continuous exposure to large quantities of information and experiences demands that the brain erase some of the old information to make room for new. This is probably why we lose the ability to speak a foreign language perfectly after the onset of sexual maturity.
The body is made up of billions of cells. In the nervous system these cells are called neurons. They are specialized to carry mess ages to the brain, and they connect to ot her neurons through branch - like structures called dendrites.Every time you learn something new-a new word, how to ride a bike or play the flute-your neurons develop new connections to other neurons. In fact, your brain eventually will form trillions of connections-that's more connections than there are stars in the entire universe!
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have one, even if diffuse neural tissue is present. It is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell.
The brain of a vertebrate is the most complex organ of its body. In a typical human the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons,[1] each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.Physiologically, the function of the brain is to exert centralized control over the other organs of the body.
The brain acts on the rest of the body both by generating patterns of muscle activity and by driving secretion of chemicals called hormones. This centralized control allows rapid and coordinated responses to changes in the environment. Some basic types of responsiveness such as reflexes can be mediated by the spinal cord or peripheral ganglia, but sophisticated purposeful control of behavior based on complex sensory inputrequires the information-integrating capabilities of a centralized brain.
From a philosophical point of view, what makes the brain special in comparison to other organs is that it forms the physical structure that generates the mind. As Hippocrates put it: "Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations."[2] Through much of history, the mind was thought to be separate from the brain. Even for present-day neuroscience, the mechanisms by which brain activity gives rise to consciousness and thought remain very challenging to understand: despite rapid scientific progress, much about how the brain works remains a mystery. The operations of individual brain cells are now understood in considerable detail, but the way they cooperate in ensembles of millions has been very difficult to decipher. The most promisingapproaches treat the brain as a biological computer, very different in mechanism from electronic computers, but similar in the sense that it acquires information from the surrounding world, stores it, and processes it in a variety of ways.
This article compares the properties of brains across the entire range of animal species, with the greatest attention to vertebrates. It deals with the human brain in so far as it shares the properties of other brains.
The ways in which the human brain differs from other brains are covered in the human brain article. Several topics that might be covered here are instead covered there because much more can be said about them in a human context. The most important is brain disease and the effects of brain damage, covered in the human brain article because the most common diseases of the human brain either do not show up in other species, or else manifest themselves in different ways.
Among the changes that occur in the body when children hit puberty, there is a slightly reduced communication time between neurons. "If you don't get rid of the noise or less useful information, it is a problem," said Tsien. While each neuron averages 3,000 synapses, their continuous exposure to large quantities of information and experiences demands that the brain erase some of the old information to make room for new. This is probably why we lose the ability to speak a foreign language perfectly after the onset of sexual maturity.
The body is made up of billions of cells. In the nervous system these cells are called neurons. They are specialized to carry mess ages to the brain, and they connect to ot her neurons through branch - like structures called dendrites.Every time you learn something new-a new word, how to ride a bike or play the flute-your neurons develop new connections to other neurons. In fact, your brain eventually will form trillions of connections-that's more connections than there are stars in the entire universe!
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