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89 Cards in this Set
- Front
- Back
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What are the exteroceptive sensory systems? |
Auditory, somatosensory (touch), olfactory, gustatory (taste), and visual |
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What are the 3 principles of interaction between the three levels of the sensory systems? |
1) Hierarchical organization 2) Functional segregation 3) Parellel processing |
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What are the three levels of the sensory system? |
Primary sensory cortex: Receives input from thalamic relay nuclei Secondary sensory cortex: Receives input from primary cortex, or secondary cortex (of other senses) Association cortex: Receives input from secondary cortex, or from other sensory cortexes |
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What is "Sensation"? |
The process of detecting the presence of stimuli |
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What is "Perception"? |
The process of integrating, recoginizing, and interpreting complete patterns of sensations |
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Explain hierarchical organization? |
Sensory structures organized in a hierarchy on the basis of specificity/complexity of function - Higher up the chain = response to more complex/specific stimuli Therefore, damage up the chain produces more specific deficits Receptors --> Thalamic relay nuclei --> primary sensory cortex --> secondary sensory cortex --> association cortex |
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Explain functional segregation? |
Within each level of the sensory system (primary, sensory, association) - different cortical areas of that system have different functions for different forms of sensory analysis - I.e. On the same level (E.g. Primary cortex), the different areas communicate with each other |
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What is parallel processing? |
Information flows through "parallel systems" - multiple pathways at once |
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What are the the 2 types of parallel streams of analysis in our sensory systems? |
1) Can influence behaviour without conscious awareness 2) Can influence behaviour by engaging in conscious awareness |
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Explain how sensory system "divides labour" when analyzing stimuli? |
So, a simple, individual stimuli (i.e. Shape, colour, etc.) may be perceived by a certain component of the system But a complex stimuli (i.e. Scene analysis) may be perceived by the whole system |
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What is the binding problem? What is the solution? |
"How does the brain combine individual sensory attributes to produce an integrated perception?" - No cortex area receives sensory input from all sensory systems Perception is considered then to be a product of combined activity in certain interconnected cortical areas |
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What range of frequencies can humans perceive? |
From 20-20,000Hz |
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What are the three characteristics of a sound? |
1) Amplitude (Loudness) 2) Frequency (Pitch) 3 Complexity (Timbre) |
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What are pure tones? |
Single sine-wave vibrations - only exist in the lab - Real-world all tones are formed from multiple series of complex sound waves |
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What is Fourier analysis? |
The procedure for breaking down complex waves into their component sine waves |
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What is the fundamental frequency? What is the missing fundamental? |
FF: The highest frequency of which a series of complex waves are multiples of (E.g. 100Hz, for a series of 100Hz, 200Hz, and 300Hz) MF: A PERCEIVED FF, when it does not actually exist (E.g. Mix of 200Hz, 300Hz, and 400Hz, would have a MF of 100HZ, even though it does not exist here) |
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What is the path of sound travel? |
Outer ear --> Auditory canal --> Tympanic membrane (eardrum) --> Ossicles (MIS/HAS) --> Oval window --> Cochlea/cochlear fluid --> Organ of corti |
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What are the three ossicles, lateral to medial? |
Malleus (Hammer) Incus (Anvil) Stapes (Stirrup) |
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What is the organ of corti? |
The auditory receptor organ, internal membrane of the cochlea |
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If there is a pressure change at the oval window, where does it travel, and how? |
Travels along the organ of corti, as a wave |
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What are the 2 membranes of the organ of corti? |
Basilar membrane: The hair cells rest here (Auditory receptors) Tectorial membrane: Rests on the hair cells |
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How does the auditory nerve fire? - which cranial nerve is it? |
Deflection the organ of corti produces a shearing force on the hair cells, stimulating them and increasing axon firing (of the auditory nerve) CN 8 - Auditory-vestbular nerve |
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Where do vibrations of the cochlear fluid dissipate? |
Along the round window (Elastic membrane of the cochlear wall) |
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How is the cochlea "coded"? |
Tonotopically - based according to frequency - Higher frequency produces stimulation of hair cells, close to windows - Lower frequency produces stimulation of hair cells, close to tip of basilar membrane |
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What are the semicircular canals? |
The receptive organs of the vestibular system - tell us about direction/intensity of head movements, in order to maintain balance |
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What is the path from the ear to the primary auditory cortex? How does signal get transmitted to both auditory cortexes? |
Auditory nerve --> Cochlear nuclei --> Superior olives, olivary neuron --> inferior colliculi (via lateral lemniscus) --> Medial geniculate nuclei (Thalamus) --> Primary auditory cortex cochlear nuclei projection to both superior olives (ipsilateral/contralateral) |
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What is the thalamus nuclei involving auditory function? |
Medial geniculate nuclei |
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What is the thalamus nuclei involving visual function? |
Lateral geniculate nuclei |
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How do the superior olives help localize sound? |
Medial superior olive: Responds to difference in time of arrival Lateral superior olive: Responds to difference in amplitude of signals |
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How is the auditory system laid out? Are there any exceptions? |
Tonotopically (Based on frequency structures, etc.) - But deep layers of superior colliculi are laid out according to a map of auditory space, to locate sources of sensory input in space (e.g. Barn owls hunting mice by their rustling in a field, at night) |
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Where is the auditory cortex located? |
Temporal lobe |
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What is "The core region" of the auditory cortex? |
Composed of the primary auditory area, and 2 other regions (The belt -- secondary cortex area....??) |
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What are the 2 "main sections" of the secondary cortex? How many areas of secondary auditory cortex in primates? |
The belt: Surrounds the core region The parabelt: All other areas 10 Areas |
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Two streams of auditory cortex: a) What are they b) Where do they go? c) What do they do? d) What part of cortex are they? |
Anterior auditory pathway: To pre-frontal cortex - Involved in identifying sounds (WHAT) Posterior auditory pathway: To **Posterior parietal cortex** - Involved in locating sounds (WHERE) d) Association cortex |
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Where do auditory-visual interactions occur? How are they investigated? |
In the association cortex (Of auditory.....AND visual(??)), specifically the posterior-parietal region - Monkey study: Some PP neurons found to have visual, or auditory receptive fields....or both - fMRI used to investigate |
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Where is the location of pitch-perception? |
Anterior to the primary auditory cortex --> Many neurons here that respond to pitch/frequency Thought to be where frequencies of sounds are converted to pitch |
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How do we study the effects of auditory cortex damage? |
Lesion the core, belt, and parabelt regions....see what happens |
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Where is MOST of the human auditory cortex? |
Within the lateral fissure |
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What are the effects of bilateral vs. unilateral lesioning to the auditory cortex? |
Unilateral lesion: Disruption of ability to localize sounds, but only OPPOSITE the lesion (contralateral side) Bilateral: Temporary full hearing loss, due to shock of lesion --> Hearing recovers in ensuing week - But, permanent impairment of discerning frequencies, and ability to localize sounds in space |
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What are the 2 classes of hearing impairment (deafness)? |
1) Conductive deafness: Ossicle damage 2) Nerve deafness: Damage to cochlea or auditory nerve - Cause: Loss of hair cell receptors (But deafness can be frequency-specific, and not for others (I.e. Age-related hear loss)) |
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What is tinnitus? |
Ringing of the ears |
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How do cochlear implants work? |
Bypass nerve damage - convert sounds picked up by a microphone to electrical signals carried directly to the cochlea |
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What are the three* interacting systems of of the somatosensory system? |
Exteroceptive system: Senses external stimuli applied to skin: - Mechnical stimuli division: Touch - Thermal stimuli division: Temperature - Nociceptive stimuli division: Pain Proprioceptive system: Monitors information about position of body (From muscles/joints/balance organs) Interoceptive system: Monitors information about the condition of the body |
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What are the 4 types of cutaneous receptors? |
1) Free nerve endings: Sensitive to temp/pain 2) Pacinian corpuscles: Respond to SUDDEN displacement of skin, but not constant pressure 3) Merkel's disks: respond to GRADUAL skin indentation 4) Ruffini endings: Respond to GRADUAL skin stretch |
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What is stereognosis? |
Identification of objects by touch (I.e. Based on their static/dynamic properties0 |
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What are dermatomes? |
Grouped areas of the body, that are innervated by the left/right dorsal roots of a segment of the spinal cord (I.e. Groupings of the body based on their innervations) |
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What are the two major somatosensory pathways? Major information they carry? |
Dorsal-Columna Medial-Lemniscus System: Information about touch and proprioception Anterolateral system: Information about pain/temperature |
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a) Where does information from the dorsal-column medial lemniscus system synapse (on the thalamus)? b) What nerve also inputs here? c) Where are the 3 places these neurons go? |
a) Ventral posterior nucleus (of the thalamus) b) Carries information from the 3 branches of the trigeminal nerve c) (Ventral posterior nucleus neurons project to) - Primary somatosensory cortex (SI) - Secondary somatosensory cortex (SII) - **Posterior parietal cortex** |
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What are the longest neurons in the body? |
Dorsal-column medial-lemniscus system nerves of the TOES |
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Do the dorsal-column medial-lemniscus system nerves decussate? |
Yes, after synapsing on the medulla |
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Anterolateral system: a) Do they decussate? b) Where do they synapse? |
a) Yes, but some ascend ipsilaterally b) Yes, at spinal cord (DCML system travels up the dorsal column...duh) |
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What are the 3 different tracts of the anterolateral system? Where do they project? |
1) Spinothalamic tract: To ventral posterior nucleus of the thalamus 2) Spinoreticular tract: Reticular formation --> Parafascicular nuclei (Thalamus) --> Intralaminar nuclei (thalamus) 3) Spinotectal tract: Tectum (i.e. Colliculi) |
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How is the human somatosensory cortex arranged? |
Somatotopically - as a map of the human body |
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What is the map of the somatosensory cortex called? What is the distribution? |
Somatosensory homunculus - bigger distribution for the areas requiring the most tactile discriminatory |
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Where does output of SI and SII tend to go to? |
Posterior parietal lobe |
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In what way are the neurons of the primary somatosensory cortex similar to the visual system neurons? |
Many neurons have excitatory/inhibitory areas, and these are arranged in columnar organization - 4 functional "strips" of somatotopic organization, that respond to different types of tactile stimulation |
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For the somatosensory system, neuron preferences become more complex when moving from which direction to where? |
Anterior to posterior areas of the body |
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What are the two streams of analysis of the SI? |
Dorsal stream: To posterior parietal cortex --> Multisensory integration, and the DIRECTION of attention Ventral stream: To SII --> Perception of objects shapes |
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What type of neurons are contained in the posterior parietal cortex (that respond to activation of two different sensory systems)? |
Bimodal neurons: Typically they are spatially related (Receptive fields respond to stimuli for different systems in the same areas, like a sight/sound on the left area, etc.) |
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What are the two types of somatosensory agnosias? |
Astereonogsia: Unable to recognize objects by touch Asomatognosia: Unable to recognize parts of one's own body - Damage to right posterior parietal lobe - Usually unilateral to left side, because of contralateral neglect |
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What is anosognosia? |
Failure of neuropsychological patients to recognize their own symptoms |
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Why is the perception of pain a paradoxical concept? (3 reasons) |
1) It is an adaptive mechanism, we are capable of feeling that something hurts so that we don't do it 2) There is no clear cortical area linked to the representation of pain 3) We can suppress it with cognitive/emotional factors |
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Inability to detect pain is linked to what? |
A gene abnormality that affects the synthesis of sodium ion channels |
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What area of the brain is MOST linked to pain experience? |
The anterior cingulate cortex |
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What is the gate-control theory? |
There are neural circuits that descend from the brain to block incoming pain signals Proof: 1) The periaqueductal gray has analgesic effects (Acts on the RAPHE NUCLEI) 2) We have receptors built-in for opiate analgesic drugs 3) Endorphins we produce are opiate analgesics - But some circuits can INCREASE pain perception |
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What is neuropathic pain? |
Chronic pain that occurs in the absence of a recognizable stimulus Caused by abnormal CNS activity (Cannot fix by amputating peripheral nerves) Linked to signal from glial cells - triggers immense hyperactivity in neural pain pathways |
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What are the chemical senses? Main purpose? |
Olfactory and gustatory (I.e. Smell and taste) For flavor recognition (I.e. Sensory impression involving excitation of both smell and taste receptors) |
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Evidence that supports humans release sexual pheromones? (4 points) |
1) Olfactory sensitivity of women is greatest during ovulation/pregnancy 2) Menstrual cycles of women who are together become synchronized 3) Humans can tell sex of person from breath/underarm odour 4) Men can judge stage of women's menstrual cycle on basis of vaginal odour - **Still no DIRECT evidence that these odours serve as sex attractants** |
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Where are the receptor cells of the olfactory system? |
In the olfactory mucosa - within layer of mucous-covered tissue |
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How many kinds of olfactory receptors do we have? |
Almost 1000 (Rats/mice have 1500) |
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What is the pathway of olfactory neurons |
Axons pass through the cribriform plate (porous section of the skull) and enter the olfactory bulbs, then project via olfactory tracts to the brain |
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How are odours encoded by component processing? |
Each olfactory receptor cell contains one type of receptor protein molecule (We have 1000 diff.) - and each receptor of a given protein projects to the same location in the olfactory bulb So, we pick up an odour of a certain kind in varying levels, and pattern the activity across the receptor types (I.e. Component processing, combine the "Key" of the odour) |
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What are the olfactory glomeruli? |
Location of olfactory receptor axon termination (near the olfactory bulbs) Input from several thousand olfactory cells (with same receptor protein) |
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Uniqueness of the olfactory cells? |
They can regenerate! New ones grow every few weeks to replace themselves |
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Where do the olfactory tracts project to in the brain? |
Primary olfactory cortex: The piriform cortex - Also amygdala These are in the medial temporal lobes |
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What are the 2 pathways that leave the amygdala/piriform cortex area? (I.e. Olfactory system) What do they do? |
1) Projection to limbic system - mediates emotional responses to odours - Mediates EMOTIONAL RESPONSE of odours 2) Projects to medial dorsal nuclei (thalamus), and orbitofrontal cortex (Near eye sockets) - Mediates conscious PERCEPTION of odours |
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What is the anatomy of the taste area? |
Taste receptors are on the tongue/oral cavity in clusters of 50 (Taste buds) - situated on the "buttons" of the tongue, the papillae |
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What are the different types of gustatory receptors? |
30 bitter receptors, 1 umami, 2 sweet (Sour and sweet act directly on ion channels, they do not have receptor proteins) - 1 Type of each present in each taste receptor cell |
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What three cranial nerves carry gustatory signals? Where on the thalamus do they eventually reach? |
Facial nerve (CN 7) - Front of tongue Glossopharyngeal nerve (CN 9) - Back of tongue Vagus nerve (CN 10) - Back of oral cavity - Reach the ventral posterior nucleus (of thalamus) |
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Where is the primary gustatory cortex? |
Near face area of the somatosensory homunculus (i.e. Superior lip of lateral fissure) |
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Where is the secondary gustatory cortex? |
Deeper in the lateral fissure |
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What is anosmia? How does it happen? |
Inability to smell - from blow to head, which shears the olfactory nerves where they pass the cribriform plate |
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What is ageusia? What link does it have to the ear? |
Inability to taste (Rare because we have 3 pathways) Facial nerve (CN 7) has a branch that passes through the middle ear, so damage to taste can be observed after damage to the ear |
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What is selective attention? What is the underlying principle? |
Ability to consciously perceive a particular set of stimuli and ignore the rest, in a given scene - Improve perception of focused stimuli - Interferes with perception of non-focused stimuli |
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What is covert attention? |
Shifting visual attention without any corresponding eye movements |
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Endogenous vs. exogenous attention? |
Endo: Internal process - mediated by cognitive processes (i.e. Top-down neural mechanisms) - Look for keys, check the table Exo: External events - Mediated by bottom-up mechanisms - Look at table because cat knocks a lamp over |
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What is change blindness? What is the requirment interval? |
Inability to detect minor changes in an environment that is otherwise the same (i.e. Two pictures with something removed) - Must be brief <1.0second interval between images....otherwise it technically doesn't require memory |
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Are neural receptive fields for attention plastic? |
Yes - a study showed they are capable of shifting based on the attentional focus applied to the stimuli and where it is |
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What is simultanagnosia? |
Difficulty in attending to more than one object at a time |
