The article linked below offers the first evidence I have seen for a diet-responsive neuogenic niche.
“Weight struggles? Blame new neurons in your hypothalamus.” May 21st, 2012.
Excerpt: “People typically think growing new neurons in the brain is a good thing – but it’s really just another way for the brain to modify behavior,” Blackshaw explains. He adds that hypothalamic neurogenesis is probably a mechanism that evolved to help wild animals survive and helped our ancestors do the same in the past.”
In my model nutrient chemicals and pheromones have direct effects on hypothalamic neurogenesis, olfactory bulb neurogenesis, and hippocampal neurogenesis. These direct effects link nutrient chemicals and pheromones to the biological core of mammalian reproduction: the hypothalamic gonadotropin releasing hormone (GnRH) pulse.
In mammals, for example, food odors and pheromones cause changes in GnRH pulse frequency that result in patterns of neurogenesis responsible for the development of behaviors associated with proper food choice (individual survival) and proper mate choice (species survival). Food odors up-regulate and social odors down-regulate the calibration of stochastic gene expression responsible for control of speciation via hippocampal neurogenesis and the required learning and memory of species specific behaviors.
The direct effect of food odors and social odors on signalling pathways makes the epigenetic effects of chemical cues as important to the understanding of human behavior as they are to the understanding of behavior in every other species. This is especially true for placental mammals.
The in utero and postnatal effect of the chemical stimuli is on the development of the hypothalamic GnRH neuronal niche, which is responsible for the conditioning of food preferences and mate preferences and the transgenerational epigenetic inheritance of all behaviors required for individual and species survival. GnRH-dependent luteinizing hormone (LH) secretion, for example, is the link between proper nutrition and reproductive sexual behavior. The feedback loops are detailed in my model for the adaptive evolution of the human brain and behavior.
Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338.