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Biopsych - exam 3


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Knee Jerk Circuit
- stretch receptors on a muscle spindle -AP (Graded) down sensory neuron (Unipolar) -Sensory neurons in DORSAL root -Synapse onto motor neuron... located in the ventral horn -glutamate released onto motorneurons -Cause EPSPs -AP down the motor neuron -syanpse onto the neuromuscular junction -release ACh -leg kicks Afferent: from quad to spinal cord Efferent: back to spinal cord -inhibitory signal to the quad -activation to antagonistic muscle (hamstring)
How did Kalivas measure motivated behavior? Test called what?
Locomotor output --> -high reactivity = move around a lot -low reactivity: don't move as much Open Field Test
3 major processes in the motive circuit
1. receive motivationally relevant information via the limbic system 2. Integration of this information to determine the intensity of the behavioral output 3. Initiation of the motor response via projections to motor nuclei
Brain regions in the limbic system
1. NAc - Shell 2. VPm 3. VTA 4. MD
Brain Regions in the Thiamocortical Subcircuit
MD and PFC
Brain Regions in the motor subcircuit
1. PFC? 2. NAc - Core 3. VPI 4. SN
Kalivas and afferent limb? Efferent limb?
Afferent - consists of VTA, Nucleus Accumbens shell, and Ventromedial ventral pallidum --> Sensory information coming in Efferent: Substantial nigra, nucleus accumnbens core, and dorsolateral ventral pallidum
Communication between the limbic and motor system
Mediodorsal thalamus and Prefrontal cortex
What does injection of AMPA, dopamine, or DAMGO (a mu agonist) into the Ventral Pallidum do?
activation of locomotor activity -these receptors are activated through the limbic pathway when an animal is dumped into a novel environment
Cornea: Lens: Pupil: Iris: Ciliary Muscle:
Cornea: The transparent outer layer of the eye, whose curvature is fixed. It bends light rays and is primarily responsible for forming the image on the retina. Lens: Structure in the eye that helps focus an image on the retina Pupil: The aperture, formed by the iris, that allows light to enter the eye Iris: Circular structure of the eye that provides an opening to from the pupil Ciliary Muscle: focus by shaping lens
Rod vs. Cone
Both: photoreceptors Rod: -"scoptic" system (dark) -no color -dim light -outside fovea -low accuity Cones: -"photopic" system (Light) -color -bright light -inside fovea -high accuity
Axons of the ganglion cells make up the _____
optic nerve
Horizontal and amacrine cells
-provide lateral inhibitory signal to bipolar and ganglion cells (lateral inhibiton) -->Horizontal: photoreceptor cells and bipolar cells --> Amacrine cells: bipolar and ganglion
Light is captured by _______
The discs of rod cells
Photons captured by _______. 2 parts:
Rhodopsin -retinal and opsin (split when light hits this photopigment)
How does light activate rhodopsin and hyperpolarize the photoreceptor cell?
-Resting conditions: Na+ channels open...held open by cGMP. -Light causes rhodopsin to split into retinal and opsin -Opsin binds with G-protein, transducin -The activated Transducin causes cGMP --> 5'GMP -Because there is less cGMP, the Na+ channels aren't held open, and therefore close... leads to hyperpolarization.
1. Hyperpolarization leads to less/more glutamate?
LESS glutamate, so photoreceptor gives off less glutamate -in light --> on center bipolar cell depolarizes (more transmitter release) and off center hyperpolarizes (less transmitter release)
When are on/off center bipolar cells excited?
On center: excited when Light is ON Off center: turning OFF light excites them
Where is the highest concentration of cones? of Rods?
Cones: fovea Rods: periphery of fovea
Visible light between ___ and ___ nm Higher frequency and lower wavelength --> blue or red? Infrared vs. ultraviolet
400 - 700 Blue: higher frequency Red: greater wavelength Ultraviolet <400nm Infrared >700nm
Trichromatic Hypothesis and why it's wrong
The hypothesis: the idea that color vision results from 3 distinct types of receptors (red, green, blue) -Wrong because you don't have just one peak, but it's more of a range with the peak being where it's most sensitive... can overlap
Color perception occurs at the ______ not the ______
Occurs at the: ganglion cells and brain NOT the photoreceptors
From the Retina to the Brain --> Describe track
-Ganglion cells --> optic nerve --> brain -Optic nerve crosses the midline at the optic chiasm and becomes the optic tract -Axons from optic tract then go to the LGN (Visual thalamus) -LGN -->occipital cortex (aka primary visual cortex, V1) -then to V2, V4, inferior temporal area (These are the extrastriate areas)
Extrastriate areas of vision
V1: primary visual cortex V2: illusory contours V4: sinusoidal frequency Inferior temporal lobe: object recognition
2 Major visual pathways Where do they start? Ventral stream includes what? Where does the dorsal stream merge?
1. Ventral --> What? 2. Dorsal --> Where? Both start in V1 Ventral stream includes: occipitotemporal, inferior temporal, and inferior frontal areas Dorsal stream merges with the motor cortex. MIRROR NEURONS.
On Center/Off surround Off Center/On surround
On center: light at center of receptive fields EXCITES these cells... fires more AP. No Light: inhibition. Off center:Light at center inhibits. No light at center, but light surround get AP.
LGN and its layers
-6 layers -2 inner layers --> magnocellular -4 outer layers --> parvocellular Magnocellular: -large receptive field -M Cells (large ganglion cells) -no differential responses to different wavelengths of electromagnetic spectrum -not involved in color discrimination Parvocellular: -small receptive fields -input comes from small ganglion cells (P Cells) -can discriminate specific wavelength (contribute to color vision)
Functions of External Ear, Middle Ear, Internal Ear
External Ear: Capture sound waves Middle Ear: (osciclles) --> Connect to ear drum and lead to opening of the inner ear (oval window) Function: sharpen, focus energy to eventually get it strong enough so it can move the fluid of the inner ear Inner ear: converts sound into neural activity (transduction)
Auditory portion of the inner ear
Cochlea --> coiled fluid filled structure
Unrolling the cochlea
-Near Oval window = base -other end --> apex -Auditory transduction is done by the organ of corti -Organ of corti contains the basilar membrane
Describe the basilar membrane
part of the organ of corti -vibrates in response to sound -high frequency vibrates near base -low frequency near apex
Hair Cells
-On the organ of corti -inner hair cells: responsible for sound perception -outer hair cells: adjust the organ of corti which helps sound information processing by inner hair cells -both inner and outer hair cells have afferents that go to cochlear nucleus of the brainstem -and efferent from the superior olivary nucleus
Sound Transduction in Hair Cells
-Stereocilia of hair cells are inserted into the tectorial membrane -sound vibrations bend these stereocilia -The bending of the stereocilia opens ion channels gated by mechanical energy -the ion channels are located near the tips of the sterocilia (tips of stereocilia have threadlike fibers --> tip links, attached to ion channels) -The opening of the channels allow K+ and Ca+2 to rush in to depolarize the hair cell -depolarization of the cell body of the hair cell allows further influx of Ca+2, which causes glutamate release that evokes action potential in the auditory afferent
From Ear to Brain
-Sensory afferents that synapse on the hair cell comprise the Vestibulocochlear nerve (Cranial Nerve VIII) -This divides into 2 main branches in the brain stem: one to the ipsilateral cochlear nucleus and the other sends projections to the contralateral cochlear nucleus -output from the cochlear nuclei travels to superior olivary nuclei (both ipsilateral and contralateral) -then to the inferior colliculus (primary auditory center of the midbrain) -main output from the inferior colliculus is the MGN (auditory thalamus) -MGN to critical auditory portions of the brain
Primary auditory center of the midbrain
inferior colliculus
Afferent and efferent in hair cells
Afferent: to cochlear membrane Efferent: from the superior olivary nucluei
Associations of Papillae, Taste Bud, and Taste receptor
Papillae (bump on tongue), taste bud on paillae, taste receptor on taste bud -at surface of taste bud is an opening called taste pore -cilia extend into the pore which contact the tastant
Tongue to Brain
Taste cell transmits info through cranial nerves (facial - 7, Glossopharyngeal -9, vagus - 10) -then gustatory signals travel to the nucleus of the solitary tract (in brainstem) -then to hypothalamus (Ventral posterior medial nucleus) -then to gustatory cortex
Taste Transduction: Salt
-Sodium ions are transported across the membranes of taste cells by sodium ion channels -Na+ entry partially depolarizes taste cells and causes them to release NT and stimulate afferent neurons
Which receptors detect Na+?
Taste Transduction: Sweet, bitter, umami
-more complex than salt -involves intracellular, G-proteins and second messengers
Which receptors are G-protein coupled receptors that have a alpha subunit that is unique to taste cells?
T1R and T2R
What is the alpha subunit in taste transduction?
Which receptor don't cats have?
T1R2 --> can't taste sweet
Which receptor is important for bitter?
What is the sheet of cells that line the dorsal portion of the naval cavity?
Olfactory epithelium...contains the receptor cells
Describe set up of olfactory system.
Olfactory receptor cells have dendrites (cilia from dendritic knob) that extend into outer layer of the epithelium -At the opposite end of the receptor cell (these are bipolar cells), there are unmyelinated axons that project to the olfactory bulb
What is the mucosal layer?
-where molecules in the air get sniffed into the nasal cavity -contains binding proteins that transport odorants to the olfactory receptors
Olfactory Receptors
members of superfamily G protein-linnked receptors -odorant interaction with olfactory receptors trigger the synthesis of 2nd messengers (including cAMP) --> causes opening of cation channels and results in depolarization of the olfactory receptor cell and action potentials down the axons that project to the olfactory bulb
What is G olf?
a gene that if knocked out (in mice) then can't smell --> anosmic
Olfactory Projections to the Brain
Axons from the olfactory receptor cells synapse within the olfactory bulb. The olfactory bulb is organized into many roughly spherically shaped neral circuits called glomerli -terminals from the olfactory receptor cell synpase on the dendrites of mitral cells within glomeruli
Olfactory receptor cells to glomeruli
each olfactory receptor cell expresses a single type of olfactory receptor each glomerulus receives input from olfactory receptor cells of a specific type
Olfactory bulb to the rest of the brain
Outputs from the olfactory bulb are carried by axons of mitral cells extend to a variety of brain regions (including pyriform and enteorhinal cortex and amygdala and hypothalamus)
Vomernosal System and Phermones
Phermone: chemical signal that is released outside of the body and affects members of the same species. Second chemical detection system that is specialized in detecting phermones phermones interact with receptors in the vomersonal organ

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