Dendrons, GnRH, life, logic, and the dynamics of information essential to adaptive evolution (sans mutations)

By: James V. Kohl | Published on: July 31, 2013

“…if signals are pulsed down a pathway and the changing outputs are monitored, much more complex information can be transmitted. A metaphor here would be the use of the Morse code and the telegraph to communicate messages. Pulses of information sent along the telegraph generate a code for letters and as a consequence sentences can be communicated. This converts the same signalling pathway from a simple on/off switch to a device that can transfer, for example, the works of Shakespeare. It is likely that dynamics has been exploited more generally in the evolution of biological systems for signalling purposes, allowing the communication of more complex information.” — Nurse (2008) Life, logic and information

GnRH Neurons Elaborate a Long-Range Projection with Shared Axonal and Dendritic Functions Michel K. Herde, Karl J. Iremonger, Stephanie Constantin, and Allan E. Herbison. J. Neurosci. 2013;33 12689-12697

Abstract excerpt: “These data demonstrate that 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.”

Article excerpt: It is interesting to speculate that the unique morphology of the GnRH neurons may result from their embryonic origin in the nose (Schwanzel-Fukuda and Pfaff, 1989; Wray et al., 1989).

My comment: GnRH neursecretory neurons allow communication of more complex information, which is consistent with Nurse’s representation of systems biology (above). See also: Nutrient-dependent/pheromone-controlled adaptive evolution: a model.

Excerpt: “For instance, ‘our experiments suggest that excitatory odor responses are transiently suppressed (in terms of overall firing rates), but more complex temporal shaping of responses may occur because of interplay of intrinsic properties, sensory drive, and the feedback activity’ (Markopoulos, Rokni, Gire, & Murthy, 2012, p. 1186). In context, this was suggested in ‘Feedback loops link odor and pheromone signaling with reproduction’ (Boehm, Zou, & Buck, 2005).”

These feedback loops that link olfactory/pheromonal input to reproduction in mammals, also link other neuronal systems involving neurosecretory neurons and effects on hormones that affect mammalian behavior during its development. For example, more than two decades ago it was known that: “Noradrenergic, dopaminergic, serotoninergic, and opiotergic pathways; inhibitory neurotransmitters (e.g., gamma aminobutyric acid) and excitatory amino acids (e.g., glutamic and aspartic acids); and other brain peptides including pineal secretions (melatonin) and corticotrophin releasing hormone affect the LHRH [GnRH]pulse generator (Grumbach & Styne, 1992 cited in Kohl, 2006).”  The demonstration by Herde et al (2013) of  the dynamic control of GnRH secretion into the pituitary portal system to regulate fertility extends it to Nurse’s Life, logic and information and to my model for the development of sexual preferences.
This moves neuroscience forward by a leap, which does not require any faith in mutations theory, or belief in what can be shown in brain imaging,  from what has been established in my model as a factual representation of how glucose and pheromones alter mammalian behavior, including human behavior via direct effects on gene activation in GnRH neurosecretory cells of the hypothalamus.

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