Brain and behavior relationships

Neurons are the initiators of all human activity, emotion, and cognition. The neural input goes down the dendritic neuron until it reaches the axon terminal, where other neurons transport it from the synapse. Action is commenced by the firing of an action potential (i.e. nerve impulse) that causes a neuron to dash down the dendrite. Neurons communicate via chemical messages called neurotransmitters that transmit the neuron and push it along from one axon to another enticing them to cross synapses whilst doing so. Sometimes the neurotransmitters impede the neurons from crossing over the synapse by inhibiting the receiving cell. At other times they excite the neuron and receptor allowing the receptor to welcome the neuron and to facilitate its passage. Neural activity is farther enhanced and regulated by other chemicals called neuropeptides. The brain, it has recently been discovered, works according to the principle of neuroplasticity, namely, it can 'rewire' itself and modify according to experience and environment.

Neuroscientists divide the nervous system into the central nervous system (CNS) comprising the main part of the brain and the peripheral nervous system (PNS) made up of spine and brain stem. The PNS includes the somatic (voluntary) and the autonomic (instinctive) nervous systems. Most of the computing (actions, emotions, decisions) is carried out by the CNS. The PNS carried sensory information to and from the brain via the brain stem and spine. Instinctive bodily processes are regulated by the autonomic nervous system in a dual process of sympathetic branch (i.e. reactive) and parasympathetic (i.e. quelling) as exemplified in the 'fight and flight response' where fear may cause an instinctive (sympathetic) reaction, instantly after subdued by the parasympathetic rejoinder.

Neuroscientists study the brain for various reasons not least to investigate the causes and brain regions of behavior as well as to better comprehend and cure pathological disease. Brain research is conducted through various forms of imagery (e.g. CT, PET, or fMRI), through simple studies / observations, or though lesioning.

The human brain, otherwise known as the cerebral cortex, is divided into left and right hemispheres connected by the corpus colluseum. Each hemisphere is divided into four lobes: the frontal lobes, parietal lobes, temporal lobes, and occipital lobes. Each has its own skills associated with that specific areas (e.g. thinking is generally associated with the frontal cortex whilst vision with the occipital lobe; the frontal lobes are associated with motor control, speech, abstract thought, and sense of self, whilst the parietal lobes contain bodily sensations and the temporal lobes record hearing). Likewise each hemisphere has its specific expertise too with the analytical left containing speech, mathematical skills, or language and the right being largely nonverbal and holistic. None of these are exclusive to one side; rather they seem to prefer one side to the other. Observation of association of capabilities to specific neural region has partially been discovered by cutting the corpus colloseum that connects the brain thus 'splitting' the two hemispheres.

The brain can be further divided into the three regions of the forebrain (the most recent part), midbrain, and hind brain (the most primitive and oldest region). The cortex (i.e. forebrain) contains our thinking apparatus, whilst the midbrain and hindbrain (otherwise known as subcortex) regulate emotion and primal action and stimuli. These include: