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level: Touch and the vestibular system

Questions and Answers List

level questions: Touch and the vestibular system

QuestionAnswer
Afferent SignalsInformation flowing inward to the CNS from sensors in the periphery.
AmplitudeIn reference to the Vestibular sensation, the size of a head movement
Active SensingSensing that includes self-generated probing of the environment. Animals use echolocation, electrical signals, whiskers/antennae etc
AmpullaAn expansion of each semicircular canal duct that inclues that canal's cupula, crista and hair cells where transduction occurs
Angular MotionRotational motion like the rotation of a spinning top or swinging saloon doors that rotate back and forth
Autonomic Nervous SystemThe part of the nervous system that is responsible for regulating many involuntary actions and that invvervates glands, heart, digestive system etc
Balance SystemThe sensory systems, neural processes and muscl,es that contribute to postural control
CristaAny of the specilised detectors of angular motion located in each semicircular canal in a swelling called the ampulla
Efferent Commands(EFF-OFF!) Information flowing outward from the CNS to the periphery
GraviceptionThe physiological stuctures and processes that sense the relative orientation of gravity with respect to the organism
Hair CellAny cell that has stereocilia for transducing mechanical movement in the inner ear into neural activity sent to the brain
KinesthesiaPerception of the position and movement of our limbs in space
Tactile AgnosiaThe inability to identify objects by touch
Substantia GelatinosaA region of interconnecting neurons in the dorsal horn of the spinal cord
SomatotopicReferring to spatial mapping in the somatosensory cortex in correspondence to spatial events on the skin
SomatosensationCollectively, sensory signals ferom the skin, muscles, tendons, joints and internal receptors
Pacinian CorpuscleA specialised nerve ending associated with fast-adapting (FA II) fibers that have large receptive fields
Merkel Cell Neruite ComplexA specialised nerve ending associated with slowly adapting (SA I) fibers that have small receptive fields
Labelled LinesA theory of sensory coding in which each nerve fiber carries a particular stimulus quality. E.g., a taste nerve fiber that responds best to sucrose but also responds with small responses to other stimuli carries only sweet
HomonculusA maplike representation of regions of the body in the brain
Gate Control TheoryA description of the pain-transmitting system that incorporates modulating signals from the brain
EgocenterThe center of a refernce frame used to represent locations relative to the body
Dorsal HornA region at the rear of the spinal cord that receives inputs from receptors in the skin
Cold FiberA sensory nerve fiber that fires when skin temperature decreases
Anterior Cingulate Cortex (ACC)A region of the brain associated with the perceived unpleasantness of a pain sensation
A-beta FiberA wide-diameter, myelinated sensory nerve fiber that transmits signals from mechanical stimulation
Vestibular OrgansSet of 5 organs - three semicircular canals and 2 otolith organs - located in the inner ear that sense head motion and head orientation with respect to gravity
UtricleOne of the two otolith organs. A saclike structure.
Spatial orientationA sense of consisting of three interacting modalities: Perception of linear motion, angular motion and tilt
Sensory integrationThe process of combining different sensory signals. Typically, combining several signals yields more accurate and/or more precise information that can be obtained from individual sensory signals. This is NOT the mathematical process of integration learned in calculus
Sense of tiltThe perceptual modality that senses head inclination with respect to gravity
SacculeOne of the two otolith organs. A saclike structure.
Semicircular CanalAny of three toroidal tubes in the vestibular system that sense angular motion
Macula1. In reference to vision, the pigmented region with a diameter of about 5.5mm near the centre of the retinar. 2. In reference to the vestibular system, any of the specilised detecors of linear acceleration and gravity found in each otolith organ
MechanoreceptorA sensory receptor that responds to mechanical stimulation (pressure, vibration or movement)
Macula1. In reference to vision, the pigmented region with a diameter of about 5.5mm near the centre of the retinar. 2. In reference to the vestibular system, any of the specilised detecors of linear acceleration and gravity found in each otolith organ
OscillatoryReferring to the back-and-forth movement that has a constant rhythm
OtoconiaTiny calcium carbonate stones in the ear that provide inertial mass for the otolith organs, enabling them to sense gravity and linear acceleration
Otolith OrgansEither of two mechanical structures (utricle and saccule) in the vestibular system that sense both linear acceleration and gravity
Reception PotentialA change in voltage across the membrane of a sensory receptor cell in response to stimulation
Sense of angular motionThe perceptual modality that senses rotation
Sense of linear motionThe perceptual modality that senses translation
Sensory ConflictDiscrepancies that arise when sensory systems provide conflicting information. E.g., vision may indicate that you are stationary while the vestibular system tells you that you are moving
Sensory ExafferenceChange in afference caused by external stimuli. For the Vestibular system, vestibular afference evoked by passive head motion would yield sensosry exafference
Sensory reafferenceChange in afference caused by self-generated activity. For the vestibular system, vestibular afference evoked by an active self-generated head motion would yield sensory reafference
SinusoidalReferring to any oscillation, such as a sound wave or rotational motion, whose waveform is that of a sine curve
Spatial DisorientationAny impairment of spatial orientation. More specifically, any immpairment of our sense of linear motion, angular motion, or tilt
TransduceTo convert one form of energy to another
VectionAn illusory sense of self-motion caused by moving visual cues when one is not , in fact, actually moving
VertigoA sensation of rotation or spinning. The term is often used more generally to mean any form of dizziness
Vestibular SystemThe vestibular organs as well as the vestibular neurons in cranial nerve VIII and the central neurons that contribute to the functional roles that the vestibular system participates in
Vestibulo-Ocular Reflex (VOR)A short-latency reflex that helps stabilise vision by counterrotating the eyes when the vestibular system senses head movement
A-delta Fiber An intermediate-sized myelinated sensory nerve fiber that transmits pain and and temperature signals
AnalgesiaDecreasing pain sensation during conscious experience
C FiberA narrow-diameter, unmyelinated sensory nerve fiber that transmits pain and temperature signals
C Tactile (CT) AfferentA narrow-diameter, unmyelinated sensory nerve fiber that transmits signals from pleasant touch
DermisThe inner two major layers of skin, consisting of nutrtitive and connective tissues, within which lie the mechanoreceptors
Dorsal Column-Medial Lemnisal (DCML) PathwayThe route from the spinal cor to the brain that carries signals from skin, muscles, tendons and joints
Endogenous OpiateA chemical released by the body that blocks the release or uptake of neurotansmitters necessary to transmit pain sensations to the brain
EndogenousIn reference to spatial attention, a form of top-down (knowledge-driven) control in which attention is voluntarily directed toward the site where the observer anticipates a stimulus will occur
EpidermisThe outer of two major layers of skin
ExogenousIn reference to spatial attention, a form of bottom-up (stimulus driven) attention reflexively (involuntarily) directed toward the site at which a stimulus has abruptly appeared
GlabrousIn reference to skin, lacking hair
Haptic perceptionKnowledge of the world that is derived from sensory receptors in skin, muscles, tendons and joints - usually involving active exploration
HyperalgesiaAn increased or heightened response to a normally painful stimulus
KinestheticReferring to perception involving sensory mechanoreceptors in muscles, tendons and joints
Meissner CorpuscleA specialised nerve ending associated with fast-adapting (FA I) fibers that have small receptive fields
NociceptorA sensory receptor that responds to painful input, such as extreme heat or pressure
ProprioceptionPerception mediated by kinesthetic and internal receptors
Ruffini EndingA specialised nerve ending associated with slowly adapting (SA II) fibers that have large receptive fields
Somatosensory Area 1 (S1)The primary receiving area for touch in the cortex
Somatosensory Area 2 (S2)The secondary receiving area for touch in the cortex
SomatotypicalReferring to normal somatosensation
Spinothalamic PathwayThe route from the spinal cord to the brain that carries most of the information about skin temperature and pain