Brain

The brain is a central component of the nervous system, a network that transmits signals to and from different parts of the body, and regulates involuntary and voluntary actions. Specialised nerve cells, or neurons, and supporting non-neuronal cells, called glia, form the basic building blocks of the nervous system.
The brain and nervous system regulate a wide variety of essential functions, including:
* Thinking, attention, reasoning and feeling emotions
* Absorbing and processing sensory information such as vision, sound, and smell
* Learning new information and committing it to memory
* Sleep and dreaming
* Physical movement and posture when walking, running, sitting or standing
* Regulating body temperature, breathing, heart rate and blood pressure
The brain is a remarkably adaptive organ. Neurons and the connections between them are continually changing, which allow us to acquire new skills, retain memories, and recover from brain injury. Neuroplasticity refers to the brain and nervous system’s ability to re-model in response to new information. Being plastic, the brain can change as a result of behaviour, emotions, external stimuli and injury.
One mechanism through which this occurs is synaptic plasticity, which occurs at synapses and is crucial for forming new memories. Another is the birth of new neurons, which is known as neurogenesis.
==Anatomy==
The brain and nervous system are made of nerve cells called neurons. Neurons send electrochemical signals to one another, forming the basis of the brain’s complex, essential functions: to form memories and thoughts, to produce actions, and to interpret the world around us. The brain contains around 100 billion neurons. But neurons don’t work alone. In fact, there are as many non-neuronal cells, called glia, in the brain as there are neurons, if not more.
The key difference between neurons and glia is that neurons are ‘excitable’. This means that they produce electrical events called action potentials, which are also known as nerve impulses, or spikes. Nerve impulses are the basic currency of the brain. They allow neurons to communicate with each other, computations to be performed, and information to be processed.
When a neuron spikes it releases a neurotransmitter, a chemical that travels a tiny distance across a synapse before reaching other neurons. Any time a neuron spikes, neurotransmitters are released from hundreds of its synapses, resulting in communication with hundreds of other neurons.
Neuronal communication is exquisitely regulated as a balance between excitatory and inhibitory influences. A given neuron receives hundreds of inputs, almost exclusively on its dendrites and cell body. These inputs add and subtract in a constantly evolving pattern, depending on what the brain is thinking. This is a process called synaptic integration, which determines whether a neuron becomes active.
In order to become active, the total input must reach a threshold at which excitation outweighs inhibition enough. Only at this point will the receiving neuron spike, adding its voice to the conversation by releasing its own neurotransmitter.
==Memory==
See article on Memory
Memory is what makes us who we are—it is the process by which we store and recall experiences, facts, and information. How does memory work? How does the brain store memories, and where is the information stored?
Category:Neuroscience