chapter 12- Spatial orientation
acceleration
a change in velocity. (mathematically, acceleration is the derivative of velocity. in words linear acceleration indicates a change in linear velocity; angular acceleration indicates a change in angular velocity)
receptor potential
a change in voltage across the membrane of a sensory receptor cell (in the vestibular system, a hair cell) in response to stimulation.
dizziness
a commonly used lay term that non-specifically indicates any form of perceived spatial disorientation, with or without instability
gravity
a force that attracts a body toward the center of the earth
fourier analysis
a mathematical procedure by which any signal in this case motion trajectories as a function of time= can be separated into components sine waves at different frequencies. combing these sine waves will reproduce the original motion trajectory
vertigo
a sensation of rotation or spinning. the term is often used more generally to mean any form of dizziness
spatial orientation
a sense consisting of three interacting modalities: perception of linear motion, angular motion and tilt
mechanoreceptor
a sensory receptor that responds to mechanical stimulation ( pressure, vibration, or movement)
vestibulo-ocular reflex (VOR)
a short-latency reflex that helps stabilize vision by counterrotating the eyes when the vestibular system senses head movement
ampulla
an expansion of each semicircular-canal duct that includes that canal's cupular, crista, and hair cells, where transduction occurs.
vection
an illusory sense of self-motion caused by moving visual cues when one is not in face actually moving
hair cell
any cell that has a stereocilia for transducing mechanical movement in the inner ear into neural activity sen to the brain, some hair cells also receive inputs from the brain
spatial disorientation
any impairment of spatial orientation. more specifically, any impairment of our sense of linear motion, angular motion or tilt
crista
any of the specialized detectors of angular motion located in each semicircular canal in a swelling called the ampulla
macula
any of the specialized detectors of linear acceleration and gravity found in each otolith organ
semicircular canal
any of three toroidal tubes in the vestibular system that sense angular motion
sensory reafference
change in afferenc caused by self-generated activity. for the vestibular system, vesibular afference evoked by an active self- generated head motion would yield sensory reafference
sensory exafference
change in afference caused by external stimuli. for the vestibular system, vestibular afference evoked by passive head motion would yield sensory exafference
mathematical intergration
computing an integral-one of the two main operations in calculus (the other is inverse operation and differentiation) . velocity is the integral of acceleration. change of position is integral of velocity
otolith organ
either of two mechanical structures (utricle and saccule) in the vestibular system that sense both linear acceleration and gravity
amplitude
in reference to vestibular sensation, the size (increase or decrease) of a head movement (with angular velocity, linear acceleration, tilt, etc.)
afferent signals
info flowing inward to the central nervous system from sensors in the periphery. passive sensing would rely exclusively on such sensory inflow, providing a traditional view of sensation
efferent commands
info flowing outward from the central nervous system to the periphery. a common example is motor commands that regulate muscle contraction. the copy of such motor commands is often called an efferent copy.
imbalance
lack of balance, unsteadiness;nearly falling over
utricle
one of the two otolith organs. a sac-like structure that contains the utriular macula. also called the utriculus
saccule
one of the two otolith organs. a saclike structure that contains the saccular macula. also called the sacculus.
kinesthesia
perception of the position and movement of our limbs in space
velocity storage
prolongation of rotational response by the brain beyond the duration of the rotational signal provided to the brain by the semicircular canals; typically yielding responses that are nearer the actual rotational motion than the signal provided by the canals
sinusoidal
referring to any oscillation, such as a sound wave or rotational motion, whose waveform is that of a sine curve. the period of a sinusoidal oscillation is the time that it takes for one full back and forth cycle of the motion to occur. the frequency of a sinusoidal oscillation is defined as the numeral 1 divided by the period
oscillatory
referring to back adn forth mvoement that has constant rhythm
angular motion
rotational motion like the rotation of a spinning top or swinging saloon doors that rotate back and forth
active sensing
sensing that includes self-generated probing of the environment. besides our vestibular sense, other active human sense include vision and touch.
sensory conflict
sensory discrepancies that arise when sensory systems provide conflicting info. for example, vision may indicate that you are stationary while the vestibular system tells you that you are moving
direction
the line one moves along or faces, with reference to the point or region one is moving toward or facing
balance
the neural process of postural control by which wieght is evenly distributed, enabling us to remain upright and stable
autonomic nervous system
the part of the nervous system that is responsible for regulating many involuntary actions that innervates glands, heart and digestive system.
sense of tilt
the perceptual modality that senses head inclination with respect gravity
sense of angular motion
the perceptual modality that senses rotation
sense of linear motion
the perceptual modality that senses translation
graviception
the physiological structures and processes that sense the relative orientation of gravity with respect to the organism
sensory intergration
the process of combining different sensory signals. typically combining several signals yields more accurate an for more precise information than can be obtained from individual sensory signals. this is not mathematical process of integration learned in calculus
angular acceleration
the rate of change of angular velocity. mathematically, the integral of angular acceleration is angular velocity, and the intergral of angular velocity is angulr displacement. angular acceleration, angular velocity, and angular displacement all mathematically represent anglur motion
linear acceleration
the rate of change of linear velocity, mathematically, the integral of linear acceleration is linear velocity, and the integral of linear velocity is linear displacement, which is also referred to as "translation." linear acceleration, linear velocity, and linear displacement all mathematically represent linear motion.
balance system
the sensory systems, neural processes, and muscles that contribute to postural control. specific components include the vestibular organs, kinesthesis vestibulo-spinal pathways, skeletal bones and postural control muscles. because of the vestibular system's crucial contributions to balance, some even informally refer to the vestibular system as the "balance system" and the vestibular organs as the "balance organs" but the balance system is much more than just the vestibular system, and the vestibular system contributes to much more than just balance
vestibular organs
the set of five sense organs-three semicircular canals adn two otolith organs- located in each inner ear that sense head motion adn head orientation with resposect to gravity.
velocity
the speed and direction in which something moves. mathematically, velocity is the integral of acceleration. in words, linear velocity is distance divided by time to traverse that distance; angular velocity is rotation angle divided by time to traverse that angle
vestibular system
the 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
otoconia
tiny calcium carbonate stones in the ear that provide inertial mass for the otolith organs, enabling them to sense gravity and linear acceleration
tilt
to attain a sloped position like that of the leaning tower of pisa
transduce
to convert from one form of energy to another (e.g., from light to neural electrical energy, or from mechanical energy to neural electrical energy)
linear motion
translational motion like the predominant movement of a train care bobblehead doll.