Showing papers by "A.D. (Bud) Craig published in 2016"

Interoception, homeostatic emotions and sympathovagal balance.

Abstract: We briefly review the evidence for distinct neuroanatomical substrates that underlie interoception in humans, and we explain how they substantialize feelings from the body (in the insular cortex) that are conjoined with homeostatic motivations that guide adaptive behaviours (in the cingulate cortex). This hierarchical sensorimotor architecture coincides with the limbic cortical architecture that underlies emotions, and thus we regard interoceptive feelings and their conjoint motivations as homeostatic emotions . We describe how bivalent feelings, emotions and sympathovagal balance can be organized and regulated efficiently in the bicameral forebrain as asymmetric positive/negative, approach/avoidance and parasympathetic/sympathetic components. We provide original evidence supporting this organization from studies of cardiorespiratory vagal activity in monkeys and functional imaging studies in healthy humans showing activation modulated by paced breathing and passively viewed emotional images. The neuroanatomical architecture of interoception provides deep insight into the functional organization of all emotional feelings and behaviours in humans. This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’.

Processing of C-Tactile Information in the Spinal Cord

Abstract: Functional brain imaging places C-tactile (CT) fibres within an interoceptive network that is important for the sensation of pleasurable touch and emotional well-being, but the circuits that relay this information from periphery to forebrain are not well understood. In vivo single unit recordings from projection neurons in lamina I of the rat spinal cord showed that the activity of CT fibres is integrated with that of nociceptors before being relayed to the brainstem parabrachial nucleus. There is at least one interneuron in the pathway that relays CT activity from mechanoreceptor to lamina I output neuron, with preliminary data suggesting that such interneurons express the γ isoform of protein kinase C and receive inputs from vesicular glutamate transporter three-labelled primary afferents. A role for CT fibres in mechanical allodynia is also suggested, as pilot data shows that these fibres can provide low-threshold inputs to sensitized nociceptive-specific lamina I projection neurons. Thus, the homeostatic signal provided via CT fibres can be directly modulated by pain, placing the CT system firmly within an interoceptive network that regulates the body’s internal environment.