In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

neurons talk each other through, Context: The brain is an organ that serves as 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 a brain; diffuse or localised nerve nets are present instead. The brain is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain is the most complex organ in a vertebrate's body. In a typical human, the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons, 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.
axons

What needs to decrease before pituitary growth hormone can increase in the blood?, Context: In addition to the negative consequences of sleep deprivation, sleep and the intertwined circadian system have been shown to have strong regulatory effects on immunological functions affecting both the innate and the adaptive immunity. First, during the early slow-wave-sleep stage, a sudden drop in blood levels of cortisol, epinephrine, and norepinephrine induce increased blood levels of the hormones leptin, pituitary growth hormone, and prolactin. These signals induce a pro-inflammatory state through the production of the pro-inflammatory cytokines interleukin-1, interleukin-12, TNF-alpha and IFN-gamma. These cytokines then stimulate immune functions such as immune cells activation, proliferation, and differentiation. It is during this time that undifferentiated, or less differentiated, like naïve and central memory T cells, peak (i.e. during a time of a slowly evolving adaptive immune response). In addition to these effects, the milieu of hormones produced at this time (leptin, pituitary growth hormone, and prolactin) support the interactions between APCs and T-cells, a shift of the Th1/Th2 cytokine balance towards one that supports Th1, an increase in overall Th cell proliferation, and naïve T cell migration to lymph nodes. This milieu is also thought to support the formation of long-lasting immune memory through the initiation of Th1 immune responses.
cortisol, epinephrine, and norepinephrine

What might have happened to purposely impose separation?, Context: Somali people in the Horn of Africa are divided among different countries (Somalia, Djibouti, Ethiopia, and northeastern Kenya) that were artificially and some might say arbitrarily partitioned by the former imperial powers. Pan-Somalism is an ideology that advocates the unification of all ethnic Somalis once part of Somali empires such as the Ajuran Empire, the Adal Sultanate, the Gobroon Dynasty and the Dervish State under one flag and one nation. The Siad Barre regime actively promoted Pan-Somalism, which eventually led to the Ogaden War between Somalia on one side, and Ethiopia, Cuba and the Soviet Union on the other.
Somali people in the Horn of Africa are divided among different countries (Somalia, Djibouti, Ethiopia, and northeastern Kenya) that were artificially and some might say arbitrarily partitioned by the former imperial powers