Enzymes-Reactions Model is used to study: dynamics, bifurcation, and chaos of the acetylcholine neurocycle (ACNC). The effects of feed choline concentrations, Acetylcholinesterase (AChE) activity as bifurcation parameters are studied. It was found that feed choline concentrations are important and have direct effect on ACNC through certain important range of parameters. Detailed bifurcation analysis is carried out in order to uncover important features of the system, such as static/dynamic bifurcation and chaos. These findings are related to the real phenomena occurring in the neurons, like periodic stimulation of neural cells and non-regular functioning of acetylcholine receptors. Results are compared to the results of physiological experiments and other published models. As there is strong evidence that cholinergic brain diseases like Alzheimer's disease (AD) and Parkinson's disease (PD) are related to the concentration of acetylcholine, the present findings are useful for uncovering some of the characteristics of this illnesses/remediation.