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.