11 Jan 2023

Why is a raven like a writing-desk (1)

(Paragraphs without sources are the author’s unsupported opinions.)

There are no known receptors for alcohol in the brain. Therefore, alcohol must react in some way with receptors for neurotransmitters. It appears that dopamine, serotonin, endogenous opioids and GABA are the —neurotransmitters most associated with activation of alcohol reward centres in the CNS of rats. 1

Acute alcohol consumption enhances the release of serotonin, GABA and taurine. It decreases neuronal excitability in rats. However, chronic alcohol consumption decreases serotonin release. In the rat, systemic administration of alcohol increases extracellular concentrations of dopamine in the nucleus accumbens region of the brain. It appears that dopamine must be released into the nucleus accumbens before the rewarding properties of alcohol can be activated. Dopamine receptor antagonists reduce lever pressing for alcohol and alcohol drinking in non-deprived rats. 1

Nucleus accumbens is a neural interface between motivation and action, playing a key role on feeding, sexual and reward behaviors. 2

GABA is the most widely distributed inhibitory neurotransmitter in the CNS. At the molecular level, GABA increases chloride ion flux in synaptic neurosomal preparations. This increase in ion flux is potentiated by alcohol, as well as by benzodiazepines and barbiturates. It has been reported that GABA is involved in regulating the inhibition of presynaptic and postsynaptic neuronal activity. The excitatory effects produced by small doses of alcohol are caused by inhibition of the GABA system, and that the sedative effects produced by large doses of alcohol are caused by activation of this system. 1

Approximately 90% of the serotonin is produced by bacteria in the intestinal tract. It is also produced in the CNS, specifically in the raphe nuclei (brainstem), Merkel cells (light tactile sensation), pulmonary neuroendocrine cells (lungs) and taste receptor cells. Serotonin is stored in thrombocytes and it is released during agitation and vasoconstriction. 1

Pulmonary neuroendocrine cells or K cells produce serotonin. They are solitary or clustered airway epithelial cells. These cells are the source of several types of lung cancer such as small cell carcinoma of the lung. 3

Walter White presumably had a non-small cell lung cancer, precisely adenocarcinoma at stage 3A. He underwent neoadjuvant radiotherapy and chemotherapy followed by a lobectomy.
Stage 3 lung cancer is inoperable by definition because of spread to the nodes. At that point operation only adds morbidity without any benefit to mortality. Neoadjuvant chemo-rt is an attempt to decrease disease burden to only the primary tumor which can then be resected.
The purpose of surgery in cancer therapy is to remove all bulky disease and then use adjuvant chemo-rt if appropriate to treat residual microscopic disease. At stage 3, that gets thrown out the window because the cancer has spread. At that point you have to ask what’s the benefit of a surgery. You won’t be able to remove all the bulky disease, and chemo-rt is more effective at treating residual or micrometastatic disease than at treating a large tumor. 4

Adenocarcinoma is a type of cancerous tumor defined as neoplasia of the epithelial tissue of glandular origin or characteristics. Neoplasia is a type of abnormal and excessive tissue growth. Epithelium is a thin, continuous, protective layer of compactly packed cells with little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. Nearly 40% of lung cancers are adenocarcinomas. Among non-smokers, adenocarcinoma is the most common lung cancer. 5

Incidence of adenocarcinoma of the lung compared to other lung cancer types

Serotonin is produced by pathogenic amoebae Entamoeba histolytica. Its effect on the human gut is diarrhea. Histolysis means disintegration and dissolution of organic tissues. 6

Naegleria fowleri is a free-living, bacteria-eating amoebae that can be pathogenic, causing a fulminant brain infection7. 16 cases occurring between 1962 and 1965 in northern Bohemia had a common source in an indoor swimmingpool 8.

Neurotransmitter is a chemical substance released by the neuron to send signals to the next neuron, while the neuromodulator is a chemical substance released by the neuron to alter the effectiveness of the signal transmission. Neuromodulator is capable of changing the effect of impulse transmission on neurons without disturbing the rate of the transmission. It happens through the control of neurotransmitters synthesis and release. 9

Hormones, neuromodulators and neurotransmitters are re-purposed molecules which were originally created either as a waste product of an organism, or by an antigen.

Natural selection is a statistical phenomenon by which an information which copies itself becomes more populous with time. An information which copies more efficiently will outnumber other information.

Evolution is an epiphenomenon whereby information increase the number of constituent parts or their relationships to increase fitness. Not every set of rules which enables information to be copied favours evolution.

The more potential energy is stored in a molecule and the less stable it is without succumbing to random energy state fluctuations, the more likely is that molecule to be exploited by natural selection.

A mosquito. In a 3 dimensional space it follows a gradient with respect to light, temperature and humidity.

Faces. We recognize a face in objects which share so little with an actual human face. This ability of our cortex to detect faces has a major influence on our experience. The system which favours our pattern matching of faces is an evolutionary advantage. However, it is in some sense arbitrary. Yet, it dominates human conscious experience.

Attention is a mechanism by which a certain area of the brain locks its access to resources. A focused area performs more thorough calculation.