In sum, Kornblith et al. (2013) demonstrate that the scene network in humans has a direct homolog in macaques. This finding is consistent with the ecological importance of scenes as the visual stimulus that is most relevant for spatial

navigation. Like us, monkeys must recognize scenes because Talazoparib chemical structure they need to know where they are in the world, and like us, they appear to have cortical machinery specialized for this task. “
“Our tactile world is rich, if not infinite. The flutter of an insect’s wings, a warm breeze, a blunt object, raindrops, and a mother’s gentle caress impose mechanical forces upon the skin, and yet we encounter no difficulty in telling them apart Selleck PLX4032 and react differently to each. How do we recognize and interpret the myriad of tactile stimuli to perceive the richness of the physical world? Aristotle classified touch, along with vision, hearing, smell, and taste, as one of the five main senses. However, it was Johannes Müller who, in 1842, introduced

the concept of sensory modalities (Müller, 1842), prompting us to ask whether nerves that convey different qualities of touch exhibit unique characteristics. Indeed, sensations emanating from a cadre of touch receptors, the sensory neurons that innervate our skin, can be qualitatively different. Understanding how we perceive and react to the physical world is rooted in our understanding of the sensory neurons of touch. The somatosensory system serves three major functions: exteroreceptive and interoceptive, for our perception and reaction to stimuli originating outside and inside of the body, respectively, and proprioceptive all functions, for the perception and control of body position and balance. The first step in any somatosensory perception involves the activation of primary sensory neurons whose cell bodies

reside within dorsal root ganglia (DRG) and cranial sensory ganglia. DRG neurons are pseudounipolar, with one axonal branch that extends to the periphery and associates with peripheral targets, and another branch that penetrates the spinal cord and forms synapses upon second-order neurons in the spinal cord gray matter and, in some cases, the dorsal column nuclei of the brainstem. Within the exteroreceptive somatosensory system, a large portion of our sensory world map is devoted to deciphering that which is harmful. Thus, a majority of DRG neurons are keenly tuned to nociceptive and thermal stimuli. The perception of innocuous and noxious touch sensations rely on special mechanosensitive sensory neurons that fall into two general categories: low-threshold mechanoreceptors (LTMRs) that react to innocuous mechanical stimulation and high-threshold mechanoreceptors (HTMRs) that respond to harmful mechanical stimuli.