Sensory Systems, Perceptions and Attention Flashcards
How is the sensory system organized?
A hierarchical organization
Flows through brain structures in order of increasing anatomical complexity
Apparent from a comparison of the effects of damage to various levels
What is functional segregation in the sensory system organization?
Different parts specialize in different kinds of analysis
Each of the 3 levels: primary, secondary, association
What is parallel processing in the sensory system organization?
Organization so that information flows between structures, simultaneously along multiple pathways
What is the function of the auditory system?
The function of the auditory system is the perception of sound
Sounds are vibrations of air molecules that stimulate the auditory system - your ears perceive someone talking as a vibrations
What parts of the ears are apart of outer ear?
Tympanic membrane (ear drum)
What parts of the ears are apart of the middle ear?
Ossicles (3 small bones)
What part of the ears are apart of the inner ear?
-Oval window
-Organ of Corti
-Hair cells of basilar membrane
-Tectorial membrane
What is the tonotopic organization?
The organization of the organ of Corti is tonotopic
Different frequencies produce maximal stimulation of hair cells at different points along the basilar membrane
Higher frequencies excite receptors closer to the oval window
Lower frequencies producing greater activation ay the tip of the basilar membrane
What is the order of the pathway from the inner ear to the primary auditory cortex?
- Hair cells synapse on neurons
- Axons enter metencephalon
- Synapse in ipsilateral cochlear nucleus
- Travel to superior olives
- Travel to the inferior colliculus via the lateral lemniscus
- Signals from each ear are combined at a low level (in the superior olives)
- Fibers ascend to the medial geniculate nucleus of the thalamus
- Fibers ascend to the primary auditory cortex in the lateral fissure
- Projections from each ear are bialateral
What is the auditory cortex?
Recieves input from medial geniculate nucleus (thalamus)
Core region (primary auditory cortex and 2 adjacent areas)
Belt surrounds the core
Parabelt areas - areas of the secondary auditory cortex but just on the outside of the belt
What is the organization of primate auditory cortex?
Tonotopically organization - responds to similar frequencies are close together
Contains functional columns - responds to similar frequencies
Poorly understood compared to vision
How does the auditory cortex integrates information?
Auditory signals are processed by two large areas of association cortex: prefrontal cortex and posterior parietal cortex
What are the two streams of the auditory cortex?
Anterior auditory pathway: identifies sound
Posterior auditory pathway: identifies where sound is
What is involved within the auditory-visual interactions
Integral part of sensory processing
Occurs in associations areas but also in primary areas (recent fMRI studies)
Some posterior parietal neurons have visual receptive fields and auditory receptive fields (work in monkeys)
What is the auditory cortex damage
Bilateral lesions do not cause deafness
Loss of the ability to process the structural aspects of sound
What occurs when their is damage to the anterior (“what”) pathway?
Difficultly identifying sounds
What occurs when their is damage to the posterior (“where”) pathway?
Difficulty localization sounds
What are some facts towards deafness in humans
Hearing impairment can lead to social isolation
Total deafness is rare (1% of hearing-impaired individuals)
What are two types of deafness within humans
Conductive deafness: damage to ossicles
Nerve deafness: damage to cochlea or nerve, loss of hair cell receptors
What is age-related hearing loss?
Part of the cochlea is damaged, results in a deficit in percieving high frequencies
High frequencies helped by hearing aids or cochlear implant
What is apart of the exteroceptive cutaneous system made up of
Mechanical stimulation: touch
Thermal stimulation: temperature
Nociceptive stimuli: surface pain
What is the proprioceptive system?
Body position
What is the interoceptive system?
Within body
What are the four types of receptors?
Free nerve endings: pain and temperature
Pacinian corpuscles: deep fast-adapting, skin displacement
Merkel receptors: slow-adapting
Ruffini corpuscles: Slow-adapting
What are the cutaneous perception?
All cutaneous receptors respond to stimuli with ion flow across membrane
What is the stereognosis?
Identification of objects by touch use both fast and slow-adapting receptors
Tactile sensations produced by multiple receptor mechanisms
Think getting dressed
You feel the shirt being put on - fast-activating receptors
Throughout the day, you don’t feel the shirt unless you think about it - slow-activating receptors
What is the dorsal-column medial-lemniscus system - one of the two major somatosensory pathways?
Carries information about touch and proprioception - the body
What is the anterolateral system - one of the two major somatosensory pathways?
Mediates pain and temperature
In order, how does information get carried through the dorsal-column-medial-lemniscus?
- Receptors enter spinal cord and ascend ipsilateral dorsal columns to the dorsal column nuclei
- Dorsal column-nuclei decussate and ascend medial lemniscus
- Travels to ventral posterior nucleus
- Axons of the ventral posterior nucleus ascend to the somatosensory cortex
In order, how does information get carried through the anterolateral system?
- Axons synapse as soon as they enter the cord
- Second-order axons decussate and travel up three pathways
Spinothalamic tract
- projects to ventral posterior nucleus of thalamus
Spinoreticular tract
- projects to reticular formation and then to parafascicular and intralaminar nuclei of thalamus
Spinotectal tract
- Projects to mesencephalic tectum
What is neuropathic pain?
Severe/chronic pain from no known stimulus
Develops after an injury
Microglia may trigger hyperactivity in pain pathways
What are the chemical senses: smell and taste.
Monitor the chemical content of the environment
What is olfaction as a chemical smell?
Airborne chemicals
What is gustation as a chemical smell?
Chemicals in solution
How are adaptive roles of the chemical senses as a humans and other species?
Humans
- chemical senses evaluate potential foods
Other species
- Chemical senses detect pheromones
- Pheromonses regulate social interactions
What is the olfactory system?
Smell is responsible to airborne chemicals
Human have 300 different olfactory receptors
Chemotopic mapping occurs
Olfactory receptor cells are produced across the lifespan and constantly replaced
What are the five primary tastes in gustatory system?
Sweet
Sour
Bitter
Salty
Umami
Where are taste receptors located?
Taste receptors are located in the tongue and throughout the gastrointestinal tract
Survive only a few weeks and are constantly replaced
What is taste transduction in the gustatory system?
For sweet, umami and bitter is mediated by metabotropic receptors (G-protein linked)
Salty and sour activate ionotropic receptors
What is anosmia as a brain damage disorder?
Inability to smell
- Caused by damage to olfactory nerves as they pass through cribriform plate
- Linked to elilepsy, down syndrome, parkinson’s, multiple sclerosis, and other degenerative disorders
What is ageusia as a brain damage disorder?
Inability to taste
- Rare
- May be caused by damage to facial nerve
What is the role of prior experience have on perception?
Prior knowledge has a major influence on how we perceive the world
What is perceptual decision making?
Mental models of the world based on predictable and recurring sensory events
Perceptual decision making consumes a large proportion of the energy used by the brain
What is the phantom limb syndrome?
Amputees brains believe that their missing limb is still there, pain may occur - tricking the brain using a mirror to make it think the missing limb is still there, which relieves the pain
What is the Charles Bonnet syndrome?
When individual is losing vision, they tend to start seeing visual hallucinations
The brain is not getting much information from the visual system, but its used to that info. Brain works on the visual system which activates these hallucinations
What is the binding problem
Addresses how complex stimuli can be percieved as integrate wholes
How does the brain combine these complex, multiple stimulus into one simple perception?
What are some characteristics of selective attention?
Improves the perception of the stimuli that are its focus, interferes with the perception of the stimuli that are not its focus
What is endogenous attention?
Focused on internal cognitive processess
Believed to be top-down (from higher to lower levels)
What is exogenous attention?
Focused on external events
Believed to be bottom-up (from lower to higher levels)
What is the cocktail-party phenomeon?
Happens in very loud environment
How do you pay attention to one person?
You drown out everything else to focus on whats important to you in that moment
Someone calls you
- you will be able to hear them
What is change blindness?
Classic example of selective attention
Demonstrated by showing people two photographs identical in every aspect but one
If allowed a brief delay, people have difficulty seeing change
Where does the top-down processing originate?
Prefrontal lobe and posterior parietal cortex
What does face identity activate?
Ventral visual pathway
What does the position of the face activate?
Dorsal pathway
What does selective attention strengthens?
Representation of attended-to stimuli
What does selective attention weakened?
Representation of external stimuli
What is visual simultanagnosia?
Difficultly attending to more than one object at a time
Occurs due to damage to the posterior parietal cortex
