Term
| What is the olfactory pathway to the brain? |
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Definition
-Olfactory neurons to mitral cells.
-Mitral cells of olfactory bulb to piriform and enthorinal cortex (primary olfactory cortex) and amygdala.
-Amygdala to medial dorsal thalamus
-Medial dorsal thalamus to orbitofrontal cortex (involved in conscious perception of flavor) |
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Term
| How are the olfactory receptors organized? |
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Definition
-There are over 1000 different olfactory receptors, any one of which is contained in cilia of olfactory neurons.
-The cilia are in contact with the mucus of the olfactory epithelium and bind the dissolved volatile substances.
-Olfactory neurons contact mitral neurons in the olfactory bulb via the short axons of the olfactory nerve. (CN1) |
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Term
| Where are the olfactory receptors located? |
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Definition
| In the roof of the nasal cavity, in the olfactory epithelium. |
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Term
| What is the gustatory pathway to the brain? |
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Definition
-Inputs from three sensory cranial nerves (facial, glossopharyngeal, and vagus) which receive synaptic inputs from taste receptors send their axons to the nucleus of the solitary tract.
-neurons of the nucleus of the solitary tract send their axons to the lateral hypothalamus, amygdala and ventral posteromedial thalamus
-Neurons in the thalamus send axons to the primary gustatory cortex
-Some neurons of primary gustatory cortex send axons to the orbitofrontal cortex. |
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Term
| How are the taste receptors organized? |
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Definition
-There are about 10,000 taste buds, each containing from 20-50 receptors cells, arranged like the segments of an orange.
-The receptors send cilia into opening of papilla, where food chemicals can bind when dissolved into saliva. Binding produces receptor potentials that are conveyed to the brain.
-Different areas of the tongue contain the receptors for the different taste qualities. |
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Term
| Where are the taste receptors located? |
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Definition
| On the tongue, palate, pharynx and larynx |
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Term
| What are the different taste "qualities" in humans? |
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Definition
| There are only 4 qualities: bitterness, sourness, sweetness, and saltiness. Sometimes Umami. |
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Term
| What are the chemical senses? |
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Definition
| Smell and taste are chemical senses because their function is to monitor chemical content (volatile substances for smell, dissolved substances for taste) of the environment. |
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Term
| What are visual receptive fields? |
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Definition
Area of visual field in retina within which it is possible for a visual stimulus to influence the firing of a given neuron.
-Receptive fields in retino-geniculate-cortical (layer IVc) pathway are circular.
-Simple cortical cells(outside of layer IVv in visual cortex) have linear or rectangular receptive fields that respond best to orientation, with antagonistic "on" and "off" receptive fields, from one eye (monocular)
-Complex cortical cells (similar to simple cortical cells with the following differences)
- larger receptive fields
- less static, respond better to moving lines or rectangles
- show responses to both eyes (binocular) |
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Term
| How does the visual system enhance edges and increase contrast? |
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Definition
-Based on firing rate of ganglion cells which is proportional to light intensity.
-Ganglion cells inhibit their neighbors = lateral inhibition
-Lead to phenomena such as Mach bands. |
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Term
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Definition
| Review visual receptive field concept; opponent colors are perceived, repectively by the center and surround fields of a ganglion cell - for example, red illumination in the center field of one ganglion cell will increase its activity, but green illumination on its surround field will inhibit the same ganglion cell's activity. The situation can be reversed (red center inhibitory, green surround excitatory, etc), and similar for the other opponents |
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Term
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Definition
Opponent colors are "linked" together
Red-green opponents
Blue-yellow opponents
Black-white opponents |
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Term
| What is the visual pathway to the brain? |
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Definition
-Ganglion cells provide axons of optic nerve.
-Optic nerve decussates (nasal hemi-retina) to contralateral brain.
-Optic tract axons innervate cells of the lateral geniculate nucleus
-From the lateral geniculate nucleus, axons project to the occipital cortex
-Some axons of ganglion cells also project to hypothalamus and superior colliculus (eye and head reflexes toward visual stimuli moving in peripheral vision.) |
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Term
| What are the mechanisms of central vs. peripheral acuity? |
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Definition
Receptive field in center of retina = fovea
- provides clear, precise color vision
- mostly populated by cones
- little convergence onto ganglion cells
Receptive field outside of fovea = periphery
- provides fuzzy, imprecise black and white vision
- mostly populated by rods;
- high degree of convergence onto ganglion cells (very sensitive to even dim light) |
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Term
| How is information transmitted in the retina? |
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Definition
| Photoreceptors (no action potentials) to bipolar neurons (no action potentials) to retinal ganglion neurons (first cells to produce action potentials) which send their axons to the brain via optic nerve |
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Term
| What is the mechanism of transduction of light into nerve impulse? |
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Definition
-Light hits photoreceptors- bleaches rhodopsin molecules that "splits" into retinal
-Retinal activates transducin
-Transducin in turn activates phosphodiesterase
-phosphodiesterase destroys cGMP
-cGMP destruction closes the cationic channels
-this hyperpolarizes the photoreceptors membrane |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| How is the retina organized? |
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Definition
| Photoreceptors (rods and cones) are in the deepest level of the retina, followed by bipolar cells and ganglion cells, which are closest to where light enters the eye. |
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Term
| What are the physical characteristics of the eye? |
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Definition
| Know the major components of the eye such as the sclera, cornea, iris, pupil, lens, ligament, ciliary muscles, retina, blind spot, optic nerve and fovea. |
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Term
| What are the 3 perceived characteristics of light? |
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Definition
| Hue, Brightness, Saturation |
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Term
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Definition
| corresponding to the spectrum (wavelength) of light |
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Term
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Definition
| corresponding to intensity of wavelength |
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Term
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Definition
| corresponding to the purity of wavelength |
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Term
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Definition
| Electromagnetic energy in a relatively narrow band of a continuum ranging from Gamma rays to AC circuits; its wavelength is measured in nanometers |
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Term
| How is the brain organized? |
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Definition
Forebrain
Midbrain
Hindbrain |
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Term
| How is the forebrain organized? |
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Definition
telencephalon (neocortex)
diencephalon |
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Term
| How is the midbrain organized? |
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Definition
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Term
| How is the hindbrain organized? |
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Definition
Metencephalon
Myelencephalon |
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Term
| What is the role of the myelencephalon (medulla oblongata)? |
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Definition
| It is the origin of several nuclei that give rise to the cranial nerves and it contains the reticular fomation, which regulates sleep and wakefulness, skeletal muscle tone, and several vital reflexes (heart rate, blood pressure, respiration, vomitting, etc) |
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Term
| What is the role of the metencephalon? |
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Definition
Cerebellum- controls motor coordination, fine motor movements and habit learning (riding a bike)
Pons- contains several nuclei of the cranial nerves, the pontine reticular formation |
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Term
| What is the role of the mesencephalon? |
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Definition
tectum- roof involved in auditory information processing and visual information processing
tegmentum- floor- contains the substatia nigra(dopamine producing cells,) ventral tegmental area, and part of the reticular formation |
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Term
| What is the role of the telencephalon in the forebrain? |
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Definition
-cerebral cortex
-basal ganglia
-limbic system |
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