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Peter John Snow (born 25 February 1948) is an Australian neuroscientist and author.
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Peter John Snow (born 25 February 1948) is an Australian neuroscientist and author.
Shortly after his birth in Jubbulpore, India, his father retired from the British Army and moved to Australia. In 1970 Snow graduated with First Class Honors in Zoology. He then enrolled in a PhD program at the University of Alberta, completing his dissertation in invertebrate neurobiology in 1974 before moving to the University Edinburgh, as a Canadian Medical Research Fellow. During this period he pioneered techniques for injecting single mammalian nerve cells with tracers and used these to extensively study the neuronal microcircuitry of the sensory systems within the spinal cord.[ citation needed ]
In 1976, Snow was awarded a Queen's Fellowship in Marine Science to study the nervous system of crustaceans at the Australian National University. In 1978, he was appointed to the faculty of the Anatomy Department, University of Queensland where, until his retirement in 1998, he supervised several large medical research programs on the plasticity of the central nervous system and the representation and control of pain. Over this period Snow also conducted extensive studies on the neurobiology of sharks and stingrays which included research on their somatosensory systems, centers of aggression and ability to withstand extreme hypoxia.[ citation needed ]
Since retiring from university Snow has devoted himself to writing 'The Human Psyche' and to delivering a number of lectures on the human psyche, including the Alberta Heritage Foundation of Medical Research Lecture.
Snow is a member of the International Brain Research Organization (IBRO) and an emeritus member of the Society for Neuroscience (USA). He was also a founding member of the Australian Neuroscience Society (retired), the Australian Physiological & Pharmacological Society (retired) and the Primate Society of America (retired)
Snow is author of numerous scientific papers, reviews and book chapters and is coauthor, with Dr. P. Wilson, of an extensive monograph on plasticity and development in the somatosensory system. In late 2009, he published the first comprehensive, neuroscientifically-based book on the human psyche.
In physiology, nociception, also nocioception; from Latin nocere 'to harm/hurt') is the sensory nervous system's process of encoding noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal to trigger an appropriate defensive response.
Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed by the brain as proprioception. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, for example, by activating motor neurons via the stretch reflex to resist muscle stretch.
Afferent nerve fibers are axons of sensory neurons that carry sensory information from sensory receptors to the central nervous system. Many afferent projections arrive at a particular brain region.
The grey column refers to a somewhat ridge-shaped mass of grey matter in the spinal cord. This presents as three columns: the anterior grey column, the posterior grey column, and the lateral grey column, all of which are visible in cross-section of the spinal cord.
A nociceptor is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sensation of pain to direct attention to the body part, so the threat can be mitigated; this process is called nociception.
The dorsal column–medial lemniscus pathway (DCML) is a sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception from the skin and joints. It transmits information from the body to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe of the brain. The pathway receives information from sensory receptors throughout the body, and carries this in nerve tracts in the white matter of the dorsal column of the spinal cord to the medulla, where it is continued in the medial lemniscus, on to the thalamus and relayed from there through the internal capsule and transmitted to the somatosensory cortex. The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem.
A dorsal root ganglion is a cluster of neurons in a dorsal root of a spinal nerve. The cell bodies of sensory neurons known as first-order neurons are located in the dorsal root ganglia.
Central pattern generators (CPGs) are self-organizing biological neural circuits that produce rhythmic outputs in the absence of rhythmic input. They are the source of the tightly-coupled patterns of neural activity that drive rhythmic and stereotyped motor behaviors like walking, swimming, breathing, or chewing. The ability to function without input from higher brain areas still requires modulatory inputs, and their outputs are not fixed. Flexibility in response to sensory input is a fundamental quality of CPG-driven behavior. To be classified as a rhythmic generator, a CPG requires:
A topographic map is the ordered projection of a sensory surface, like the retina or the skin, or an effector system, like the musculature, to one or more structures of the central nervous system. Topographic maps can be found in all sensory systems and in many motor systems.
Group C nerve fibers are one of three classes of nerve fiber in the central nervous system (CNS) and peripheral nervous system (PNS). The C group fibers are unmyelinated and have a small diameter and low conduction velocity, whereas Groups A and B are myelinated. Group C fibers include postganglionic fibers in the autonomic nervous system (ANS), and nerve fibers at the dorsal roots. These fibers carry sensory information.
In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch, as well as temperature (thermoception), body position (proprioception), and pain. It is a subset of the sensory nervous system, which also represents visual, auditory, olfactory, gustatory and vestibular stimuli.
The wide dynamic range (WDR) neuron was first discovered by Mendell in 1966. Early studies of this neuron established what is known as the gate control theory of pain. The basic concept is that non-painful stimuli block the pathways for painful stimuli, inhibiting possible painful responses. This theory was supported by the fact that WDR neurons are responsible for responses to both painful and non-painful stimuli, and the idea that these neurons could not produce more than one of these responses simultaneously. WDR neurons respond to all types of somatosensory stimuli, make up the majority of the neurons found in the posterior grey column, and have the ability to produce long range responses including those responsible for pain and itch.
Somatosensory evoked potential is the electrical activity of the brain that results from the stimulation of touch. SEP tests measure that activity and are a useful, noninvasive means of assessing somatosensory system functioning. By combining SEP recordings at different levels of the somatosensory pathways, it is possible to assess the transmission of the afferent volley from the periphery up to the cortex. SEP components include a series of positive and negative deflections that can be elicited by virtually any sensory stimuli. For example, SEPs can be obtained in response to a brief mechanical impact on the fingertip or to air puffs. However, SEPs are most commonly elicited by bipolar transcutaneous electrical stimulation applied on the skin over the trajectory of peripheral nerves of the upper limb or lower limb, and then recorded from the scalp. In general, somatosensory stimuli evoke early cortical components, generated in the contralateral primary somatosensory cortex (S1), related to the processing of the physical stimulus attributes. About 100 ms after stimulus application, additional cortical regions are activated, such as the secondary somatosensory cortex (S2), and the posterior parietal and frontal cortices, marked by a parietal P100 and bilateral frontal N140. SEPs are routinely used in neurology today to confirm and localize sensory abnormalities, to identify silent lesions and to monitor changes during surgical procedures.
Edward Roy Perl was an American neuroscientist whose research focused on neural mechanisms of and circuitry involved in somatic sensation, principally nociception. Work in his laboratory in the late 1960s established the existence of unique nociceptors. Perl was one of the founding members of the Society for Neuroscience and served as its first president. He was a Sarah Graham Kenan Professor of Cell Biology & Physiology and a member of the UNC Neuroscience Center at the University of North Carolina School of Medicine.
A spinal interneuron, found in the spinal cord, relays signals between (afferent) sensory neurons, and (efferent) motor neurons. Different classes of spinal interneurons are involved in the process of sensory-motor integration. Most interneurons are found in the grey column, a region of grey matter in the spinal cord.
Tactile induced analgesia is the phenomenon where concurrent touch and pain on the skin reduces the intensity of pain that is felt.
The Golgi tendon organ (GTO) is a proprioceptor – a type of sensory receptor that senses changes in muscle tension. It lies at the interface between a muscle and its tendon known as the musculotendinous junction also known as the myotendinous junction. It provides the sensory component of the Golgi tendon reflex.
Presynaptic inhibition is a phenomenon in which an inhibitory neuron provides synaptic input to the axon of another neuron to make it less likely to fire an action potential. Presynaptic inhibition occurs when an inhibitory neurotransmitter, like GABA, acts on GABA receptors on the axon terminal. Or when endocannabinoids act as retrograde messengers by binding to presynaptic CB1 receptors, thereby indirectly modulating GABA and the excitability of dopamine neurons by reducing it and other presynaptic released neurotransmitters. Presynaptic inhibition is ubiquitous among sensory neurons.
An axo-axonic synapse is a type of synapse, formed by one neuron projecting its axon terminals onto another neuron's axon.
Sandra M. Garraway is a Canadian-American neuroscientist and assistant professor of physiology in the Department of Physiology at Emory University School of Medicine in Atlanta, Georgia. Garraway is the director of the Emory Multiplex Immunoassay Core (EMIC) where she assists researchers from both academia and industry to perform, analyze, and interpret their multiplexed immunoassays. Garraway studies the neural mechanisms of spinal nociceptive pain after spinal cord injury and as a postdoctoral researcher she discovered roles for both BDNF and ERK2 in pain sensitization and developed novel siRNA technology to inhibit ERK2 as a treatment for pain.
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