Lack of a gender detection region for face stimuli

Full text available for free: The gender of face stimuli is represented in multiple regions in the human brain Alumit Ishai, Christian Kaul, Geraint Rees Published on 21 January 2011

“Given the evolutionary importance of gender information and its fundamental nature in face processing, it is plausible that there is no “gender-detection region” in the human brain, but rather, gender information is a distributed attribute.”

The lack of a “gender-detection region” is a telling feature of how gender perception works in other animals and in humans, because no neurophysiological mechanism has been proposed that enables the differences in perception of male and female faces. In other animals, the perception of males and females is associated with olfactory/pheromonal input rather than consciously perceived visual input.

If, as it appears to be, gender information is a distributed attribute, it seems more likely to be steroid hormone-dependent due to the effects of differences in steroid hormones on the brain structures where information must be integrated in gender detection. Olfactory/pheromonal stimuli have effects on levels of steroid hormones that cause sex differences in these brain structures. Given existing animal models, gender perception is more likely to result from associations between the effects of olfactory/pheromonal stimuli on the development of hormone-dependent brain structures than it is to result directly from visual input. One reason for the focus on olfactory/pheromonal input is because there is no neurophysiological mechanism that allows visual input to elicit the effects that are frequently, if not always, attributed to visual input. Another reason, is because we do not typically attribute to visual input the development of food preferences, which we seem to somehow know are dependent on olfactory stimuli.

In my olfactory/pheromonal model, sexual preferences are like food preferences that develop under the influence of what might be metaphorically termed “the mind’s eyes.”  The mind’s eyes consist of a distributed neuronal network that collectively integrates responses to olfactory and visual input. Studies of non-human mammals indicate that visual input has relatively little impact on the development of sexual preferences.

Mmy model focuses on olfactory input.  It incorporates well-conserved molecular biochemical networks of the metabolic, signaling, and regulatory types, which are essential to the development of behavior in all organisms. This behavior included the identification of conspecifics and the development of sexual preferences.  My  model also provides a detailed gene–cell–tissue–organ–organ system pathway from sexually dimorphic hormone-associated olfactory input and from MHC/HLA-associated olfactory input to sexually dimorphic behavior.

Obviously, there is more to human pheromones than meets the eyes.

Author: jim