Aging and natural death: loss of consciousness?
It is well known that old animals and humans tend to be less aware or conscious (Cheng et al. , 2020). The ability to learn, and form new memory are significantly reduced. At the synaptic level, it has been reported that hippocampal late-phase LTP is impaired in old animals that performed poorly in memory tests. In those animals that show normal memory performance, late-phase LTP is normal (Bach et al. , 1999). This finding suggests the importance of synaptic LTP in age-related memory loss. Recently, it has also been reported that synaptic tagging in the ACC is reduced in middle-aged animals (Zhou et al. , 2023). Similarly, synaptic plasticity is less robust in the aged animals’ cortex. It is quite possible that these reduced synaptic LTP and tagging will contribute to altered consciousness levels in orders. It will be very important to investigate the last moments of natural death by aging if the loss of consciousness is due to the failure of synaptic transmission and plasticity in the brain. Natural death due to aging may be related to changes in consciousness or shutdown of the consciousness network. It remains to be explored if deep brain stimulation and/or novel chemicals that increase synaptic activity/plasticity may prolong life before natural death.