Figure 1 Schematic representation of a parasagittal section of the human brain, showing the neuroanatomical projections involved in parasympathetic nervous system activation for neuroprotection. ( A ) Afferent vagus nerve pathway (represented by deep blue color ): Afferent vagus nerve neurons synapse bilaterally on the nucleus tractus solitarius (NTS) in the medulla oblongata. The NTS makes projections to various brain structures including the locus coeruleus (LC), which is the main source…
The locus coeruleus is a small, bluish part of the brainstem that releases norepinephrine, the neurotransmitter responsible for regulating heart rate, attention, memory and cognition.  It appears to be the first place affected by late onset Alzheimer’s disease.
Locus Coeruleus

Fly Me to the Moon

Locus coeruleus - Wikipedia
The Big Bang Theory - Fat Jokes About The Locus Coeruleus - Refrigerator Magnet @ #NiftyWarehouse #BigBangTheory #TV #Show #BigBangTheoryShow #BigBangTheoryTVShow #Comedy
Amygdalar Gating of Early Sensory Processing through Interactions with Locus Coeruleus | Journal of Neuroscience
Saatchi Art Artist April Zanne Johnson; Painting, "Locus Coeruleus" #art

Locus Coeruleus

‘Ground Zero’ Of Alzheimer’s: Locus Coeruleus Identified As Critical Starting…
Locus coeruleus - Wikipedia, the free encyclopedia
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A critical but vulnerable region in the brain, the locus coeruleus (pictured in blue), is subject to damage decades before symptoms of dementia appear, scientists have discovered

Scientists pinpoint exact area of the brain where Alzheimer's begins

Midbrain Activation  The periaqueductal grey and locus coeruleus conjointly act with another major half of the brain attached worry, anxiety, and panic attacks-the midbrain.

Midbrain Activation

Locus Coeruleus (location)
Ketamine blocks glutamate NMDA receptors in the brain. Increases brain-derived neurotrophic factor (BDNF, important for long-term memory and the creation of new synapses) and restores healthy mushroom-shaped spines on the dendrites of neurons in the prefrontal cortex.  It may also affect the monoamines norepinephrine (NE) and dopamine. In rats, increased the firing rate of NE neurons in the locus coeruleus and also increased spontaneous firing dopamine cells in the ventral tegmental area.
See figure: 'Neurochemical targets of methamphetamine. The picture shows the...' from publication 'The Effects of Locus Coeruleus and Norepinephrine in Methamphetamine Toxicity' on ResearchGate, the professional network for scientists.