<P> Emotions are generally defined as two - step multicomponent processes involving elicitation, followed by psychological feelings, appraisal, expression, autonomic responses, and action tendencies . Attempts to localize basic emotions to certain brain regions have been controversial, with some research finding no evidence for specific locations corresponding to emotions, and instead circuitry involved in general emotional processes . The amygdala, orbitofrontal cortex, mid and anterior insula cortex and lateral prefrontal cortex, appeared to be involved in generating the emotions, while weaker evidence was found for the ventral tegmental area, ventral pallidum and nucleus accumbens in incentive salience . Others, however, have found evidence of activation of specific regions, such as the basal ganglia in happiness, the subcallosal cingulate cortex in sadness, and amygdala in fear . </P> <P> The brain is responsible for cognition . The brain gives rise to countless cognitive processes that constitute cognition as a whole; however, higher cognitive function is derived from the set of executive functions, which are a group of cognitive processes that allow the cognitive control of behavior: selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals . Executive functions include the ability to filter information and tune out irrelevant stimuli with attentional control and cognitive inhibition, the ability to process and manipulate information held in working memory, the ability to think about multiple concepts simultaneously and switch tasks with cognitive flexibility, the ability to inhibit impulses and prepotent responses with inhibitory control, and the ability to determine the relevance of information or appropriateness of an action . Higher order executive functions require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence (i.e., reasoning and problem solving). </P> <P> The prefrontal cortex plays a significant role in mediating executive functions . Neuroimaging during neuropsychological tests of executive function, such as the stroop test and working memory tests, have found that cortical maturation of the prefrontal cortex correlates with executive function in children . Planning involves activation of the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex, angular prefrontal cortex, right prefrontal cortex, and supramarginal gyrus . Working memory manipulation involves the DLPFC, inferior frontal gyrus, and areas of the parietal cortex . Inhibitory control involves multiple areas of the prefrontal cortex as well as the caudate nucleus and subthalamic nucleus . Task shifting doesn't involve specific regions of the brain, but instead involves multiple regions of the prefrontal cortex and parietal lobe . </P> <P> Brain activity is made possible by the interconnections of neurons that are linked together to reach their targets . A neuron consists of a cell body, axon, and dendrites . Dendrites are often extensive branches that receive information in the form of signals from the axon terminals of other neurons . The signals received may cause the neuron to initiate an action potential (an electrochemical signal or nerve impulse) which is sent along its axon to the axon terminal, to connect with the dendrites or with the cell body of another neuron . An action potential is initiated at the initial segment of an axon, which contains a complex of proteins . When an action potential, reaches the axon terminal it triggers the release of a neurotransmitter at a synapse that propagates a signal that acts on the target cell . These chemical neurotransmitters include dopamine, serotonin, GABA, glutamate, and acetylcholine . GABA is the major inhibitory neurotransmitter in the brain, and glutamate is the major excitatory neurotransmitter . Neurons link at synapses to form pathways and elaborate neural networks, and the activity between them is driven by the process of neurotransmission . </P>

The largest and most recently developed part of the brain is the