Modifica di Complex Systems (sezione)

===Brainstem and Mastication===
[[File:Segmentazione Trigeminale.jpg|left|thumb|500px|'''Figure 2:''' Segmentation of Trigeminal Nervous System]]
The brainstem district is a relay area that connects the upper centres of the brain, the cerebellum, and the spinal cord, and provides the main sensory and motor innervation of the face, head, and neck through the cranial nerves.

This plays a determining role in regulation of respiration, locomotion, posture, balance, excitement (including intestinal control, bladder, blood pressure, and heart rate). It is responsible for regulating numerous reflexes, including swallowing, coughing, and vomiting. The brainstem is controlled by higher Cerebral Centers from cortical and subcortical regions, including the Basal Ganglia Nuclei and Diencephal, as well as feedback loops from the cerebellum and spinal cord. Neuromodulation can be achieved by the ‘classical’ mode of glutammatergic neurotransmitters and GABA (gamma-amino butyric acid) through a primary excitation and inhibition of the ‘anatomical network’, but can also be achieved through the use of transmitters acting on G-proteins. These neuromodulators include the monoamine (serotonine, noradrenaline, and dopamine) acetylcholine, as also glutamate and GABA. In addition, not only do neuropeptides and purines act as neuromodulators: so do other chemical mediators too, like Growth Factors which might have similar actions.<ref>{{Cite book 
 | autore = Mascaro MB
 | autore2 = Prosdócimi FC
 | autore3 = Bittencourt JC
 | autore4 = Elias CF
 | titolo = Forebrain projections to brainstem nuclei involved in the control of mandibular movements in rats
 | url = https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0722.2009.00686.x
 | volume = 
 | opera = Eur J Oral Sci
 | anno = 2009
 | editore = 
 | città = São Paulo, Brazil
 | ISBN = 
 | PMID = 20121930
 | PMCID = 
 | DOI = 10.1111/j.1600-0722.2009.00686.x
 | oaf = <!-- qualsiasi valore -->
 | LCCN = 
 | OCLC = 
 }}</ref>

The neural network described above does not end with the only correlation between trigeminal somatosensory centres and other motor areas but also strays into the amigdaloidei processes through a correlation with the trigeminal brainstem area. The amygdala becomes active from fear, playing an important role in the emotional response to life-threatening situations. When lab rats feel threatened, they respond by biting ferociously. The force of the bite is regulated by the motor nuclei of the trigeminal system and trigeminal brainstem Me5.The Me5 transmits proprioceptive signals from the Masticatory muscles and parodontal ligaments to trigeminal nuclei and motors. Central Amygdaloid Nucleus (ACe) projections send connections to the trigeminal motor nucleus and reticular premotor formation and directly to the Me5.

To confirm this, in a study conducted among mice, the neurons in the Central Amigdaloide nucleus (ACe) were marked after the injection of a retrograde tracer(Fast Blue), in the caudal nucleus of the Me5, indicating that the Amigdaloians send direct projections to the Me5, and suggest that the amygdala regulates the strength of the bite by modifying the neuronal activity in the Me5 through a neural facilitation.<ref>{{Cite book 
 | autore = Shirasu M
 | autore2 = Takahashi T
 | autore3 = Yamamoto T
 | autore4 = Itoh K
 | autore5 = Sato S
 | autore6 = Nakamura H
 | titolo = Direct projections from the central amygdaloid nucleus to the mesencephalic trigeminal nucleus in rats
 | url = https://pubmed.ncbi.nlm.nih.gov/21640334/
 | volume = 
 | opera = Brain Res
 | anno = 2011
 | editore = 
 | città = 
 | ISBN = 
 | PMID = 21640334
 | PMCID = 
 | DOI = 10.1016/j.brainres.2011.05.026 
 | oaf = <!-- qualsiasi valore -->
 | LCCN = 
 | OCLC = 
 }}</ref>

Modifying occlusal ratios can alter oral somatosensory functions and the rehabilitative treatments of the Masticatory system should restore somatosensory functions. However, it is unclear why some patients fail to adapt to the masticatory restoration, and sensomotor disorders remain. At first, they would seem to be structural changes, not just functional ones. The primary motor cortex of the face is involved in the generation and control of facial gold movements and sensory inputs or altered motor functions, which can lead to neuroplastic changes in the M1 cortical area.<ref name="MFCF" /><ref>{{Cite book 
 | autore = Avivi-Arber L
 | autore2 = Lee JC
 | autore3 = Sessle BJ
 | titolo = Dental Occlusal Changes Induce Motor Cortex Neuroplasticity
 | url = https://journals.sagepub.com/doi/10.1177/0022034515602478
 | volume = 
 | opera = J Dent Res
 | anno = 2015
 | editore = International & American Associations for Dental Research
 | città = Toronto, Canada
 | ISBN = 
 | PMID = 26310722
 | PMCID = 
 | DOI = 10.1177/0022034515602478
 | oaf = <!-- qualsiasi valore -->
 | LCCN = 
 | OCLC = 
 }}</ref>