Linking discoveries of two ‘mini-neural computers’ in the brain
October 27, 2013 | James Kohl
First ‘mini-neural computer’ discovered
Excerpt: “…GnRH neurons elaborate a previously uncharacterized neuronal projection that functions simultaneously as an axon and dendrite. This structure, termed a “dendron,” greatly expands the dynamic control of GnRH secretion into the pituitary portal system to regulate fertility.”
My comment: In mammals, the dynamic control of GnRH secretion involves the nutrient-dependent molecular mechanisms involved in self-assembly of the brain and its self-organization. The plasticity of self-organization is a function of feedback loops that link nutrient uptake and the metabolism of nutrients to species-specific pheromones which enable self vs non-self recognition in species from microbes to man. The epigenetic effects of pheromones on GnRH in mammals mimic the epigenetic effects of glucose (associated with food odors) on GnRH in mammals.
Second ‘mini-neural computer’ discovered
Excerpt 1: “As the mice viewed visual stimuli on a computer screen, the researchers saw an unusual pattern of electrical signals – bursts of spikes – in the dendrite.
Smith’s team then found that the dendritic spikes occurred selectively, depending on the visual stimulus, indicating that the dendrites processed information about what the animal was seeing.”
Excerpt 2: “All the data pointed to the same conclusion,” Smith said. “The dendrites are not passive integrators of sensory-driven input; they seem to be a computational unit as well.”
My comment: Earlier this year researchers reported that Olfaction spontaneously highlights visual saliency map. Clearly, what the “animal was seeing” (above) had already been paired with the epigenetic effects of olfactory/pheromonal input on GnRH-secreting ‘dendrons’ during the development of its behavioral response. In the dendron-dendritic pairing that links sensory input to the behavioral response, the role of visual input and dendrites is always secondary since only olfactory/pheromonal input on the GnRH ‘dendrons’ directly effects genes in hormone-secreting nerve cells of tissue in the mammalian brain.
Thus, the computations in dendrites driven by visual input (October 2013) may be added to the computations made in “dendrons” (July 2013) in the context of gonadotropin releasing hormone (GnRH)-controlled fertility, which is nutrient dependent and pheromone-controlled in mammals such as mice, and also in microbes such as yeasts (See: Signaling Crosstalk: Integrating Nutrient Availability and Sex). This links nutrient-dependent pheromone-controlled reproduction in species from microbes to man via the same molecular mechanisms whether or not the species has eyes, and whether or not specific individuals are congenitally blind.
Abstract conclusion from the Second ‘mini-neural computer’ discovered: “Together, our results suggest that dendritic spikes that are triggered by visual input contribute to a fundamental cortical computation: enhancing orientation selectivity in the visual cortex. Thus, dendritic excitability is an essential component of behaviourally relevant computations in neurons.”
What’s missing from details of this “essential component of behaviourally relevant computations in neurons” is the fact that the computations are only behaviorally relevant via associations with the epigenetic effects of olfactory/pheromonal input on that hormones that link the salience of the visual input to odors.
What’s missing from evolutionary theory is any evidence that mutation-initiated natural selection could result in epigenetically-effected self-assembly of proteins required for cell-level and organism-level survival. Without the self-assembly of proteins and self-organization of behavioral responses to food odors and pheromones, no mammal would survive with or without visual input.
Experimental evidence of two ‘mini-neural computers’ pits self-assembly, self-organization, and plasticity of the adaptively evolved mammalian brain against the experimentally unsupported idea of mutation-initiated natural selection and concept of mutation-driven evolution. As should already have occurred, experimental evidence will someday force evolutionary theorists to abandon their theories and face the biological facts repeatedly brought to their attention in the context of new discoveries.