Neuro
Human visual light range: 400-700nm
Retina: innermost layer of the eye, contains 100 million photoreceptors
Ciliary body: contains a muscular component that shapes the lens; aqueous humor produced here
Path of light: cornea, anterior chamber, pupil, lens, vitreous humor, fovea
Ametropia: some type of refractive error
Emmetropia: normal vision, image falls on the retina
myopia: nearsightedness, image falls in front of retina
Hyperopia: farsightedness, image falls beyond the retina
astigmatism: distorted/blurred vision because of defective curvature in the lens or cornea
Pinhole effect: how the pupil works, reducing size of the hole through which light passes, thereby preventing unfocused light to fall onto the retina and create blurred vision
fovea: where visual acuity is the highest, cones most highly concentrated here, located in the center of the macula lutea
Scotoma: “blind spot,” where the ganglion cell axons leave the eye and then become the optic nerve—NO PHOTORECEPTORS
Visual field: the visual space each eye sees, divided into L/R and temporal/nasal halves
Binocular depth perception: caused by overlap of the left and right visual fields
Rods and cones: photoreceptors in outer nuclear layer
Bipolar cells and horizontal cells: interneurons in outer plexiform layer
Amacrine cells: cell bodies in inner nuclear layer
Retinal ganglion cells: end cells in inner plexiform layer, axons exit the eye as the optic tract
phototransduction: conversion of photons into electrical signals (transducer), carried out by rods and cones, which do not depolarize nor produce action potentials
hyperpolarization: caused by light activation, change in the rate of neurotransmitter release onto postsynaptic neurons
Rods express: rhodopsin
Cones express: opsins (3 kinds: short, medium, long wavelength)
Intrinsically photosensitive ganglion cells express: melanopsin
Phototransduction in LIGHT: transducin, 2nd messenger activated, closure of Sodium and Calcium channels
Phototransduction in DARK: opening of calcium channels leads to neurotransmitter release
Rod numbers and density: throughout retina (with EXCEPTION of fovea) greatly EXCEEDS that of cones
Rods exhibit high degree of: convergence
Each cone receives ____ from a bipolar neuron: only one contact
Rods are ____ sensitive than cones: MORE, activated by as much as a single photon
Cones require ___ photons to activate them: >100
Which photoreceptor has LOW spatial resolution, but is extremely light-sensitive (operating well at low illumination levels): rods
Scoptopic vision: light sensitivity, operating well at low illumination levels, RODS
Which photoreceptor has HIGH spatial resolution, but not sensitive to low light (highly sensitive to bright light): cones
Photopic vision: highly sensitive to bright light, CONES
Color contrast: an object can appear to be of a different color when its surroundings are different
Color constancy: an object can appear to be of the same color when its surroundings are of similar colors/characteristics
ON-center ganglion cell: fires action potentials when illuminated in the receptive field
OFF-center ganglion cell: decreases firing action potentials when light is decreased in receptive field; fires action potentials when not illuminated (light off)
ON/OFF ganglion cells: respond transiently to BOTH increases and decreases in light
Horizontal cells: use GABA
Amacrine cells: use GABA, glycine, acetylcholine, dopamine, and glutamate
Retino-recipient brain regions: process image-forming information, all generate parallel pathway
Retino-no-recipient brain regions: process non-image forming information, suprachiasmatic nucleus and olivary pretectal nucleus
Thalamocoritcal relays: in lateral geniculate
Retino-geniculo-cortical pathway: project to layer 4 of primary visual cortex
Damage to retino-geniculo-cortical pathway: lead to visual field deficits, depending on where in the pathway such damage occurred
anopsias: large visual field deficits
hemianopsia: half of both visual field are affected
Cellular and columnar organization of primary visual cortex: 6 cellular
Pyramidal neurons of primary visual cortex: layer 2, 3, 5, 6, release glutamate to subcortical & other cortical targets
Layer 4 of primary visual cortex: spiny stellate cells, primary target of extremely dense projecting axons from lateral geniculate, appears as STRIPES (striate)
Preferred orientation: the orientation of a stimulus to which a cortical neuron maximally responds (peak of the tuning curve)
Extra striate visual areas: other cortical areas devoted to visual processing of information from the primary visual cortex, HIERARCHICAL PROCESSING
Ventral stream: recognizes the object/scene, starts at primary visual cortex->inferior temporal cortex, asks “WHAT?”
Dorsal stream: analysis of motion and spatial relationships; starts at primary visual cortex -> medial temporal area, asks “WHERE?”
Pupillary dilation controlled by: autonomic nervous system, cranial nerve III (oculomotor), contains preganglionic parasympathetic neurons
Ciliary muscles in the “near response:” thicken and round up the lends when viewing something near v. far
Suspensory ligaments in the “near response:” exert tension v. Lens elasticity determine the shape of the lens
Near-response: when viewing a close object, accommodation, convergence, and constriction are required for optimal acuity
Conjugate eye movements: coordinated movements by both eyes by cooperating extra ocular eye muscles so that binocular fixation is maintained
2 eye movements for redirecting gaze: smooth pursuit and saccadic eye movements
Smooth pursuit: both eye shift their positions in a slow, smooth, continuous motion to track a moving object
Saccadic eye movements: rapid, sudden change in eye position to redirect focus from one are to another
Saccadic suppression: prevents a blurring of the visual percept as an object image sweeps across the retina; inability to detect a visual percept during saccadic eye movement
Olfactory cells are classified as what kind of receptor: chemoreceptors
Area of sensory input that can change the firing rate of a neuron: the receptive field
Exploration and perception of somatosensory stimuli using active touching and proprioception: Haptic Touch
Right visual field is controlled by: the right eye
With shingles, the rash will often follow the distribution of nerves on the skin, these areas are called: dermatomes
Lateral axons coming from the retina decussate where: they don’t! They remain ipsilateral
Small, pointed, cartilaginous bump on the outer ear that projects over the ear canal: trigs
Tube most important for maintaining air pressure in the middle ear: eustachian/auditory tube
Potassium-rich fluid fills both the cochelear duct and the membranous labyrinth, bathing the apical end of the hair cells: endolymph
Perilymph: potassium POOR and bathes the basal end of the hair cells
anosmia: inability to smell
Melatonin produced by: pineal gland
5 established tastes detectable by gustatory cells: bitter, sweet umami, sour, salty
White matter tract connecting the septal nuclei and hypothalamus with the hippocampus: fornix
The inability to verbally respond results from damage to: Broca’s area/motor speech area
Nicotonic receptors respond to which common neurotransmitter: acetylcholine
Which cranial nerves could you test with a test for swallowing and the pharyngeal gag reflex: glossopharyngeal (IX) and vagus (X)
Which cranial nerve is associated with some shoulder & neck muscles: spinal accessory (IX)
How many MIXED cranial nerve PAIRS exist in humans: 4! Trigeminal, facial, glossopharyngeal, vagus
Bell’s palsy is associated with which cranial nerve: facial (VII)
The notochord is critical for embryonic development. It is formed from which germ layer: mesoderm
Brain volume __ after the age of five in humans: CHANGES
The primary brain vesicles that ultimately gives rise to the cerebral cortex: telencephalon
Failure of the iris of the eye to form is called: aniridia
Axon regrowth is more likely to happen in which nervous system: peripheral
Do neural crest cells arise from the dorsal or the ventral aspect of the neural tube: dorsal
The hypothalamus arises form which of the secondary brain vesicles: diencephalon, prosencephalon is primary
After peripheral nerve damage, pharmacological blockage of which glial cell type would most directly prevent repair: Schwann cells/neurolemmocytes
Trouble reading is associated with damage to which part of the eye: fovea
An object in the inferior, nasal quadrant of the visual field would be mapped on which quadrant of the retina: superior, temporal
Animals are most sensitive to which kind of taste: bitter
General somatic sensation is elicited by exogenous chemical stimuli and among other functions, can detect potentially harmful chemicals. Ans example is the burning sensation associated with capsaicin: chemesthesis
Parkinson’s disease: neurodegenerative brain disorder caused by progressive degeneration in the dopaminergic-producing neurons of the SUBSTANTIA NIGRA (part of the basal ganglia)
Raphe nuclei, part of the reticular formation, found along the midline of the brainstem are most associated with which neurotransmitter: serotonin
Pain that is perceived as coming from a site other than its origin: referred pain