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38 Cards in this Set
- Front
- Back
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What are the sensory areas of the cortex?
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<B>Primary</b> – input mainly from thalamic relay nuclei
For example, striate cortex receives input from LGN <B>Secondary</b> –input mainly from primary and secondary cortex within the sensory system <B>Association</b> – input from more than one sensory system, usually from secondary sensory cortex |
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What are the Principles Guiding the Interactions of Sensory Cortex�?
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<b>Hierarchical Organization</b>
<sub> -Specificity and complexity increases with each level -Sensation – detecting a stimulus -Perception – understanding the stimulus </sub> <b>Functional Segregation Parallel Processing |
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What is the visual cortex?
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<B>Primary</b> (V1) – posterior occipital lobe
<B>Secondary</b> <sub> -Prestriate cortex – a band of tissue surrounding V1 -Inferotemporal cortex </sub> <b>Tertiary</b> – various areas, largest single area is in posterior parietal cortex |
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What are Scotomas ?
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an <B>area of blindness</b> resulting from damage to visual cortex - part of visual field is missing
Blind in corresponding contralateral visual field of both eyes Deficit may not be readily detected due to phenomenon of completion Patient may not even know if they have it if it is small |
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What is blindsight?
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The ability to <B>respond to a visual stimulus even with no conscious awareness of the stimulus</b> (due to a scotoma)
May be that some connections still exist in V1, allowing for reactions without awareness May be that message gets to the brain by connections that do not pass through the damaged area (i.e., LGN to V2) |
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What is blindsight? pt2
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has vision but is simultaneously blind in some regards
will say they cannot see anything at all, but if you test them they show the have some visual input - set something in front of them "i see nothing" - ask them to reach out and grab it - they will reach out and grab it - processing vision on some level - not consciously |
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What are Dorsal Streams ?
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“where”/control of behavior
V1 to dorsal prestriate cortex to posterior parietal goes from occipital lobe to perietal lobes (dorsal steam) wherepath=where in relation to our body/where in space also known as control of behaviour pathway |
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What are ventral streams?
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“what”/conscious perception
V1 to ventral prestriate cortex to inferotemporal cortex helps to identify objects semantic information this visual object is a water bottle - we drink water, we can bring it places, it's made of plastic, etc <sub>*Both “where”/“what” and behavior/perception distinctions are supported by effects of damage |
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What is Prosopagnosia ?
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can't recognize faces
supports the “control of behavior” vs “conscious perception” theory Agnosia – failure of recognition Visual agnosia – able to see, but unable to recognize - inability to perceive faces based on vision Prosopagnosia – an agnosia for faces |
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What is Prosopagnosia? pt2
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Prosopagnosics are unable to recognize particular faces – they also are unable to recognize other specifics – which chair, which cow, etc. - specific dogs, specific cars, specific houses
There is an inability to recognize specific objects belonging to a complex class of objects Note – some cases where deficits are limited to faces have been observed |
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What is Prosopagnosia? pt3
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A result of bilateral damage to the ventral “what”/conscious perception stream
Thus, unconscious recognition can be preserved altered skin conductance responses to familiar vs. unfamiliar faces |
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What is Fusiform face area?
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activity increased during face recognition but not recognition of other objects
Areas in ventral stream may be specific to humans, cats, or houses But – more than one area responds to each class and there is great overlap |
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What is audition?
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Audition - the sense of hearing
Frequency - the number of complete wavelengths that pass a point in a given time Pitch - a tone’s highness or lowness depends on frequency |
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What are parts of the ear?
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<B>Middle Ear</b>
chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window <B>Inner Ear</b> innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs |
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What is the anatomy of the ear?
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<B>Tympanic membrane</b> - eardrum (movement on eardrum causes movement in three small bones, known as the ossicles )
<B>Ossicles</b> - (transfer vibrations to cochlea) <sub> bones in middles ear malleus (hammer) incus (anvil) stapes (stirrup)</sub> <B>Cochlea</b> - snail shaped structure which contains hair cells (where the transduction takes place - filled with fluid - stirrup pushes on window - causes vibrations in the cochlea fluid) <B>Oval Window</b> - place on cochlea where the stapes presses (3 bones cause oval to move) |
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What is the cochlea?
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Organ of Corti - organ on the basilar membrane which contains hair cells
<sub> Hair cell - receptive cell <sub>Basilar membrane - a membrane in the cochlea that contains the organ of corti <sub>Tectorial membrane - above the basilar membrane, cilia of hair cells move against the tectorial membrane |
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What is auditory transduction?
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Hair cells
<sub>Inner - inside the cochlear coil Outer </sub> Tip links - the more it moves towards the tallest cell, the more likely it'll send a signal - through tip links that it knows it is going the right direction - it's being bent over - as it moves towards the tallest one, increases chances of ion channels opening When the bundle is straight there is a 10% chance of ion channels being open As the bundle moves toward the tallest cillia the ion channels allow more K+ and Ca+ to enter and depolarize the cell |
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What is the auditory pathway?
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Cochlear nerve - bipolar neuron whose cell body is located in the cochlear nerve ganglion
95% of neurons in the cochlear nerve are from inner hair cells, which are myelinated The other 5% originate in outer hair cells and are unmyelinated |
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What is the central auditory pathway?
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Cochlear nucleus -> Superior olivary complex (in the medula) -> lateral lemniscus (bundle of fibers) -> inferior colliculus (low level auditory reflexes) -> medial geniculate nucleus -> auditory cortex
Superior olivary complex - a group of nuclei in the medulla, code for spatial location Lateral lemniscus - a band of fibers that carry auditory information through the medulla and pons to the inferior colliculus |
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What is the central auditory pathway? pt2
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Inferior colliculus
Medial geniculate nucleus - part of thalamus Auditory cortex - temporal lobe, <sub>-Tonotopic representation - topographical organization of frquencies |
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How are vision and auditory organized?
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Vision organized retnotopically
Auditory organized tonotopically |
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What is Perception of Spatial Location�?
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Phase difference - difference in arrival times of sound waves at each of the ear drums
-<sub>Detected by the medial superior olivary complex Intensity differences -<sub>Lateral superior olivary complex |
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What is somatosensation?
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bodily sensations
Somatsensory system is 3 separate and interacting systems <sub>Exteroreceptive – external stimuli Proprioceptive – body position (if you close your eyes and dont use visual input, you still know what ways your body is contorted in ) Interoceptive – body conditions (e.g., temperature and blood pressure) Exteroreceptive – 3 divisions |
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What is the Exteroreceptive System ?
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Touch (mechanical stimuli)
Temperature (thermal stimuli) Pain (nociceptive stimuli) Specialized receptors respond to the various stimuli |
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What are cutaneous receptors?
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Free nerve ending - temperature and pain
Pacinian corpuscles - adapt rapidly, large and deep; onion-like - sudden displacements of the skin Merkel’s disks – gradual skin indentation Ruffini endings – gradual skin stretch |
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What are cutaneous receptors? pt2
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We respond to change – when there is no change, no sensation
Stereognosis – identifying objects by touch Dermatome – the area of the body innervated by the left and right dorsal roots of a given segment of spinal cord |
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What are Ascending Somatosensory Pathways ?
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<B>Dorsal-column medial-lemniscus system</b>
-Touch and proprioception -1st synapse in the dorsal column nuclei of the medulla <B>Anterolateral system</b> -Pain and temperature -Synapse upon entering the spinal cord -3 tracts – spinothalamic, spinoreticular, spinotectal |
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What is the Somatosensory cortex ?
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<B>Primary somatosensory cortex</b> (SI)
-postcentral gyrus -somatotopic -more sensitive > more cortex input largely contralateral <B>SII</b> – mainly input from SI somatotopic, input from both sides of the body Much of the output from SI and SII goes to association cortex in posterior parietal lobe |
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What is Somatosensory Agnosias ?
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<B>Asterognosia</b> – inability to recognize objects by touch
-pure cases are rare – other sensory deficits are usually present <B>Asomatognosia</b> – the failure to recognize parts of one’s own body – the case of the man who fell out of bed |
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What is pain?
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Despite its unpleasantness, pain is adaptive and needed
No obvious cortical representation (although the anterior cingulate gyrus appears involved in emotional component) Descending pain control – pain can be suppressed by cognitive and emotional factors - if you have a stone in your shoe and someone keeps mentioning that it must hurt you - it'll hurt you more. if you focus on something else, you won't notice it as much |
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What is the Descending Pain Control Circuit ?
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3 discoveries made this possible:
1. Electrical stimulation of the periaqueductal gray (PAG) has analgesic (pain-blocking) effects 2. PAG and other brain areas have opiate receptors 3. Existence of endogenous opiates (natural analgesics) - endorphins |
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What are the chemical senses?
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<B>Olfaction</b> (smell)
detects airborne chemicals <B>Gustation </b>(taste) Responds to chemicals in the mouth Food acts on both systems to produce flavor |
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What are pheromones?
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Chemicals that influence that behavior of conspecifics (members of the same species)
Evidence of human pheromones? <sub>Changes in olfactory sensitivity across and menstrual cycle Synchronization of menstrual cycles Sex differences in odors Men can identify menstrual stage by smell |
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What is olfaction?
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Receptors embedded in the olfactory mucosa of the nose
Thousands of olfactory receptor proteins New receptors are created throughout life |
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What is gustation?
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Receptors in tongue and oral cavity in clusters of about 50 called taste buds
> 4 (sweet, sour, salty, bitter) primary tastes – 5th is umami, meat or savory Many tastes not created by combining primaries Salty and sour don’t have receptors, they merely act on ion channels |
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What is Brain Damage and the Chemical Senses ?
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<B>Anosmia</b> – inability to smell
Most common cause is a blow to the head that damages olfactory nerves Incomplete deficits seen with a variety of disorders <B>Ageusia</b> – inability to taste Rare due to multiple pathways carrying taste information |
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What is selective attention?
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Improves perception of what is attended to and interferes with that which is not
Internal cognitive processes (endogenous attention) and external events (exogenous attention) focus attention Change blindness – no memory of that which is not attended to |
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What is selective attention? pt2
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Cocktail phenomenon – indicates that there is processing of information not attended to
Simultanagnosia – a difficulty attending to more than one visual object at a time Bilateral damage to the dorsal stream (involved with localizing objects in space) |
