Vestibular SystemFunctions of Vestibular SystemBalance, equilibrium, posture, head, body, eye movementVestibular LabyrinthOtolith organs - gravity and tiltSemicircular canals - head rotationUse hair cells, like auditory system, to detect changes (transduction)Signaling Mechanism Of Vestibular SacsReceptive organ (macula) located horizontally (floor) in the Utricle and vertically (wall) in the Saccule when head is uprightcalcium crystals (otoliths) move gelatinous cap upon head movement or linear head acceleration;- embedded stereocilia of hair cells move;as with auditory hair cells, this ↑or↓ polarization, and ↑or↓ rate of action potentials in Scarpa’s vestibular neuronsSemicircular Canalssignal head’s rotational acceleration;mainly due to inertial resistance of endolymph movement;induces bending of Cupula → bending of embedded stereocilia of hair cells;regulates activity of Scarpa’s vestibular neuronsVestibulo-Ocular Reflex (VOR)Function: Line of sight fixed on visual targetMechanism: Senses rotations of head, commands compensatory movement of eyes in opposite directionConnections from semicircular canals, to vestibular nucleus, to cranial nerve nuclei  excite extraocular musclesThe Visual World!LightElectromagnetic radiationWavelength, frequency, amplitudeElectromagnetic energy: visible light = small partPerceived color of light is determined by 3 characteristics (properties of electromagnetic energy):Hue: the spectrum (wavelength) of light (color);Brightness: height of wavelength (amplitude);Saturation: “purity” of wavelengthAnatomy of The EyePupil: Opening where light enters the eyeSclera: White of the eyeIris: Gives color to eyesCornea: Glassy transparent external surface of the eyeOptic nerve: Bundle of axons from the retinaImage Formation on Retina:Structure of The RetinaDirect (vertical) pathway:Ganglion cells↑Bipolar cells↑PhotoreceptorsStructure of The RetinaRetinal processing also influenced by lateral connections:Horizontal cellsReceive input from photoreceptors and project to other photoreceptors and bipolar cellsAmacrine cellsReceive input from bipolar cells and project to ganglion cells, bipolar cells, and other amacrine cellsLaminar Organization of The RetinaInside-outLight passes through ganglion, bipolar, amacrine, and horizontal cells before reaching photoreceptors!NRSC 2100 1st Edition Lecture 16Vestibular System• Functions of Vestibular System– Balance, equilibrium, posture, head, body, eye movement• Vestibular Labyrinth– Otolith organs - gravity and tilt– Semicircular canals - head rotation– Use hair cells, like auditory system, to detect changes(transduction)Signaling Mechanism Of Vestibular SacsReceptive organ (macula) located horizontally (floor) in the Utricle and vertically (wall) in the Saccule when head is upright- calcium crystals (otoliths) move gelatinous cap upon head movement or linear head acceleration;- embedded stereocilia of hair cells move;-as with auditory hair cells, this ↑or↓ polarization, and ↑or↓ rate of action potentials in Scarpa’s vestibular neuronsSemicircular CanalsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• signal head’s rotational acceleration;• mainly due to inertial resistance of endolymph movement;• induces bending of Cupula → bending of embedded stereocilia of hair cells;• regulates activity of Scarpa’s vestibular neuronsVestibulo-Ocular Reflex (VOR)– Function: Line of sight fixed on visual target– Mechanism: Senses rotations of head, commands compensatory movement of eyes in opposite direction– Connections from semicircular canals, to vestibular nucleus, to cranial nerve nuclei  excite extraocular musclesThe Visual World!• Light – Electromagnetic radiation – Wavelength, frequency, amplitudeElectromagnetic energy: visible light = small part Perceived color of light is determined by 3 characteristics (properties of electromagnetic energy):• Hue: the spectrum (wavelength) of light (color);• Brightness: height of wavelength (amplitude);• Saturation: “purity” of wavelengthAnatomy of The Eye• Pupil: Opening where light enters the eye • Sclera: White of the eye• Iris: Gives color to eyes• Cornea: Glassy transparent external surface of the eye• Optic nerve: Bundle of axons from the retinaImage Formation on Retina:Collection of light by the eye, focuses light on retina through corneaAccommodation (change of lens shape) allows extra focusing power for near objects (< 9 m)!Structure of The Retina• Direct (vertical) pathway:– Ganglion cells ↑– Bipolar cells ↑– Photoreceptors Structure of The RetinaRetinal processing also influenced by lateral connections:– Horizontal cells• Receive input from photoreceptors and project to other photoreceptors and bipolar cells– Amacrine cells• Receive input from bipolar cells and project to ganglion cells, bipolar cells, and other amacrine cellsLaminar Organization of The Retina– Inside-out– Light passes through ganglion, bipolar, amacrine, and horizontal cells before reaching