Memory is a vital biological function without which life is not possible. The information is stored in brain by coordinated action of neuronal networks. Neurodegenerative diseases more prominently affect brain functions, particularly learning and memory processing that lead to memory dysfunction and dementia which disturbs cognitive and intellectual functioning of brain due to neuronal damage. In addition to the structural changes, there are marked alterations in neurotransmitter systems occur inside the brain which are responsible for alteration in behavior of animals. So, behavioral disturbances cannot be assigned to alterations in any single neurotransmitter as it is the result of complexity of brain neuronal circuitry, the interactions among different neurotransmitters, and the varied effects of these neurotransmitters at different synapses. The neurotransmitter abnormalities induced alterations in animal’s behavior form the basis for pharmacological intervention. The utmost important behavioral disorder focused in this thesis is the dementia particularly the Alzheimer’s disease (AD) and senescence-related dementia, in which the person’s ability to memorize declines due to compromised neuronal transmission. Till today, effective cure or therapy for treating dementia is lacking, or if available, then providing only a short-term symptomatic relief and is associated with several adverse effects, so identification of safe, simple, effective and inexpensive drugs to treat or prevent memory disturbances and cognitive deficits is the major goal of neuroscientists nowadays. Although multiple neurotransmitters are implicated in cognitive processing but the aminergic (glutamate, GABA) and cholinergic (acetylcholine) neurotransmitters have more powerful influence on cognitive function than the monoaminergic transmitters (dopamine, serotonin and norepinephrine). Evidence showed the significant role of associative processes in cognitive processing based on glutamatemediated neurotransmission and displayed the involvement of inter-neuronal interactions and connections, for memory formation, among cholinergic, glutamatergic, and GABAergic systems. Thus, the objective of current thesis is to explore the role of aminergic (glutamate, GABA) and cholinergic (acetylcholine) neurotransmitters in learning and memory processing and formation and in development of neurocognitive disorders associated dementia. In addition, the impact of dietary supplementation of aminergic (glutamate, GABA) and cholinergic (choline) neural precursors were also investigated, on cognitive and motor skills of adult rats and in treating memory dysfunctions and dementia associated with AD and aging at both behavioral and mechanistic (oxidative and neurochemical) level. Basically, current dissertation is contributing small part in the progress of developing and designing anti-dementia therapies via targeting cholinergic, glutamatergic and GABAergic systems. The cognition enhancing strategies addressed here are repetition (repeated training or learning trials) and dietary intervention of neural precursors of ACh (choline), Glu and GABA. First, the alterations in cholinergic, glutamatergic and GABAergic neurotransmission were determined along with monitoring changes in monoaminergic and oxidative systems during repetitive training or learning trial exposure on spatial and emotional memory-specific behavioral tasks. It is found that compared to extensive repetitive exposure, limited exposure is more beneficial in improving memory acquisition, short-term retention and long-term consolidation via inducing positive alterations in neurotransmitter levels and redox profile of brain. Second, effect of multiple dementia-inducing conditions [i.e. pharmacological (Scopolamine-induced and corticosterone-induced), Environmental (Aluminum-induced and Noise-stressinduced) and physiological (natural aging)] in rats were monitored on cholinergic, aminergic and monoaminergic neurotransmitters to select a specific, effective and appropriate dementia model which can be used in further therapeutic experiments. It is demonstrated that scopolamine-induced dementia model is a better rodent dementia model to explore novel therapeutic strategies targeting more specifically the underlying pathogenic mechanisms in AD. Brain function specially the cognitive performance has been evidenced to be modulated by nutritional consumption via altering the neurochemical systems. The beneficial impact of dietary amino acid neural precursors like tryptophan, tyrosine, phenylalanine and methionine is widely studied for improving neurological functioning but the effect of dietary intervention of neural precursors or neurotransmitters like choline, glutamate and GABA are less likely studied so this thesis is further aimed to assess the potential role of chronic dietary intervention of choline, Glu and GABA in improving cognitive (across three cognitive domains spatial, recognition, and associative memory) and psychomotor skills and in prevention of cognitive deficits and neurochemical disturbances observed in dementia associated with AD and aging. Chronic dietary intervention is selected due to the reason that nutritional intervention is reported to show their best effect upon long-term administration instead of acute. Findings showed that among the glutamate family (inter-related) amino acids/compounds (glutamine, glutamate and GABA), the chronic dietary supplementation of glutamate has a most beneficial impact on memory and motor performance of adult rats as well as on oxidative and neurochemical status of brain and hippocampus (memory-specific region). The chronic supplementation of choline (ACh precursor) is also found to be effective in enhancing cognitive and locomotor function by modulating neurochemical and oxidative systems. So, choline and glutamate supplements can be suggested as an effective and beneficial strategy to treat and prevent dementia. Keeping in view the coordinated and facilitated interplay of cholinergic and glutamatergic neurotransmission in memory processing and cognition, it can be hypothesized that supplementation of choline and glutamate combination might be more influential in enhancing memory and cognitive performance. Results obtained further have strengthened our hypothesis as, a profound improvement in cognitive function and locomotor performance was observed following administration of combination of choline and glutamate both at behavioral and mechanistic level (improved neurochemical and redox profile of brain) in healthy adult rats. Furthermore, in the last section of this dissertation the impact of combined supplementation of choline and glutamate was demonstrated in preventing memory dysfunctions i.e. dementia associated with AD and aging. Findings revealed the positive potential of choline and glutamate combination in preventing and treating behavioral, neurochemical and oxidative disturbances that were observed in AD-like dementia (in scopolamine-induced dementia model) and in age-related dementia (in senescent rats). In addition, the observed therapeutic potential of choline and glutamate combination is better than the already available anti-dementia combination therapy (memantine and donepezil) which is till now considered as a rational approach to treat dementia and AD but providing symptomatic relief only and also associated with several adverse effects. Moreover, during designing this therapeutic strategy, all factors (maximally as much as possible) regarding drug proposal are considered to propose a simple, safer, effective and inexpensive therapeutic strategy to treat memory dysfunction and dementia. In this thesis the use of drugs can be a re-proposition and cheaper than available anti-dementia drugs. The supplements were administered orally at doses equivalent to adequate human intake levels (calculated accordingly) for chronic period with less adverse effects that is safer and simple for dietary intervention. Their therapeutic potential is higher than the already available anti-dementia drug regimen (memantine and donepezil) suggesting its effectiveness in preventing dementia related cognitive and neurological disturbances. Thus, chronic supplementation of choline and glutamate combination can be suggested as an effective anti-dementia therapeutic strategy to prevent and suppress AD- and age-related cognitive decline by improving redox status and cholinergic, glutamatergic and GABAergic neurotransmission." xml:lang="en_US