Dr. Yoram Ben-Shaul

Dr. Yoram Ben-Shaul

Dr. Yoram Ben-Shaul

Room Number: bld 3 floor 6 Academic Unit: School of Medicine-IMRIC-Medical Neurobiology
p: +97226757419

Research Interests:

Neuronal Processing underlying Reproductive Function

What does computation have to do with reproductive function?   
After all, thinking is unnecessary and usually even disruptive for sex. Nevertheless, sexual motivation and behavior are both outcomes of non-trivial computations. To execute these computations, the brain must evaluate information about the potential partner, the environment, and the individual itself. Integration of sensory inputs with internal states is a general issue that the brain has to solve for various types of behaviors, not just reproduction. One reason for focusing on reproduction is that it involves relatively stereotyped neuronal circuitry – this facilitates their analysis. More importantly, these behaviors are simply fascinating to us, in animals, and even more so in humans. Our broad goal then, is to understand how the brain integrates sensory information with the individual’s internal physiological state to control reproductive physiology and behavior. 

 

How are socially relevant chemical cues detected and processed to control reproductive function?

Sexual behavior and sexually related physiological changes are controlled by neurons in the hypothalamus, a brain region with numerous sub-divisions containing intermixed and interrelated neuronal populations. To a large extent, these hypothalamic populations are conserved among species, and thus studies in mammalian animal models are highly relevant to humans. Yet, there are major differences among species in the sensory modalities that modulate these hypothalamic populations. While in humans, vision, olfaction, audition, and touch all play important roles, in rodents (which account for most mammalian species), chemosensation is the dominant modality.  

 I​n mice, chemical cues are detected by multiple chemosensory systems. Our research primarily involves the vomeronasal system because it is strongly implicated it in controlling reproductive function.  Indeed, vomeronasal  sensory neurons are a major source of input to hypothalamic neurons. Yet, they do not target hypothalamic neurons directly. Rather, the immediate target of vomeronasal sensory neurons is the accessory olfactory bulb (AOB), which is thus the first brain region with access to vomeronasal chemosensory information. Accessory olfactory bulb neurons then send axons to more centrally located regions, primarily to the vomeronasal amygdala which contains neurons that directly reach the hypothalamus. This completes a pathway that starts with stimulus detection at the vomeronasal organ and ends with hypothalamic activation.

The brain regions that link vomeronasal sensory neurons to the hypothalamus are not merely passive relays. Instead, each has distinct roles in the process of combining sensory information with external states to control reproductive function. On a phenomenological level, we study the neuronal activity in each of these brain regions upon exposure to various sensory cues and under various internal states. Such experiments have already provided important insights on the distinct features of each of these brain regions. However, a mechanistic understanding of information processing involves understanding the functional links between neurons in different brain regions and between internal sensors of the physiological state and these neurons. We believe that both lines of research are required to provide a complete explanation of the neuronal control of reproductive function.