The ventral-hypothalamic input route: a common neural network for abstract cognition and sexuality

Classically, external receptors of the body transmit information from the environment to the cerebral cortex via the thalamus. This review explains and argues that only concrete external information is transmitted from peripheral receptors to the cortex via a thalamic route, while abstract and sexual external information are actually transmitted from peripheral receptors to the cortex through a cognitive hypothalamic route. Sexual function typically implies participation of two distinct partners, ensuring reproduction in many species including humans. Human sexual response involves participation of multiple (environmental, biological, psychological) kinds of stimuli and processing, so the understanding of sexual control and response supposes integration between the classical physiological mechanisms with the more complex processes of our 'mind'. Cognition and sexuality are two relational functions, which are dependent on concrete (colours, sounds, etc.) and/or abstract (gestures, facial expression, how you move, the way you say something seemingly trivial, etc.) environmental cues. Abstract cues are encoded independent of the specific object features of the stimuli, suggesting that such cues should be transmitted and interpreted within the brain through a system different than the classical thalamo-cortical network that operates on concrete (material) information. Indeed, data show that the cerebral cortex is capable of interpreting two distinct (concrete and abstract) formats of information via distinct and non-compatible brain areas. We expand upon this abstract-concrete dichotomy of the brain, positing that the two distinct cortical networks should be uploaded with distinct information from the environment via two distinct informational input routes. These two routes would be represented by the two distinct routes of the ascending reticular activating system (ARAS), namely the classical/dorsal thalamic input route for concrete information and the ventral hypothalamic input route for abstract cognition and sexuality. Physiologically, the hypothalamic (dual-autonomic) route of the ARAS that processes abstract and sexual information is incompatible with the thalamic (somatic) route of the ARAS that processes concrete information, such that the two distinct routes would be needed to support the mind processes (awareness, consciousness, sexuality) through their own informational inputs from the environment. Informationally, the concrete external data are differentiated from abstract and sexual external data, so that they should be transmitted to cortex through distinct input routes. Pathologically, the hardware and/or software impairments of the hypothalamic default-mode network generate disturbed messages within the brain (related to information transmitted on this route), laying at the basis of mental and sexual disorders. The novel conceptualisations presented in the present paper help address issues surrounding the mind-brain dichotomy and, in doing so, suggest new possible avenues for exploration in the treatment and interventions for cognitive and sexual problems.