Lecture 5: Perception Mechanisms Flashcards
receive stimuli outside of our bodies
exteroceptive sensory systems
Process of detecting the presence of stimuli
sensation
Higher-order process of integrating, recognizing, and interpreting patterns of sensations
perception
types of sensory areas of cortex
- primary sensory cortex
- secondary sensory cortex
- association cortex
Areas that receive most of their input from the (1) primary sensory cortex or (2) other areas of secondary sensory cortex (in same system)
secondary sensory cortex
Area that receives most of its input directly from the the thalamic relay nuclei
primary sensory cortex
Any area that receives its input from more than one sensory system
association cortex
most input in the association cortex comes via areas of __________
secondary sensory cortex
Characterizes the interactions among the three types of sensory cortex and among other sensory structures
three major principles
three major principles
- hierarchical organization
- functional segregation
- parallel processing
“Sensory structures are organized based on the specificity and complexity of their function”
hierarchical organization
“Each of the 3 cortex levels in a sensory system contain functionally distinct areas that specialize in different kinds of analysis”
functional segregation
“information flows through the components over multiple pathways”
parallel system
“simultaneous analysis of a signal in different ways by multiple parallel pathways of a neural network”
parallel processing
Vibrations of air molecules (that stimulate the auditory system)
sounds
human hearing capacity
20 - 20,000 hertz
amplitude =
loudness
frequency =
pitch
complexity =
timbre
A sound of one single frequency
pure tone
pure tone exists only in
- laboratories
- sound recording studios
related to fundamental frequency
pitch
Mathematical procedure for breaking down complex waves into their component sine waves
fourier analysis
Transmit sound vibrations from the external ear to the middle ear (particularly the ossicles)
tympanic membrane (eardrum)
3 small bones; Connected to each other and send the sound vibrations (which they amplify) to the inner ear (particularly the cochlea)
ossicles
3 small bones
- malleus
- incus
- stapes
the hammer
malleus
the stirrup
stapes
the anvil
incus
junction point between the middle ear and the inner ear
oval window
long, coiled tube with an internal structure (Organ of Corti) running almost to its tip
cochlea
cochlea is filled with ____ that ripples due to the vibrations
fluid
‘different hair cells respond to different frequencies of sound’
tonotopic
bundles of stereocilia move along the waves created by the rippling (due to vibration)
organ of corti
organ of corti convert wave movements into ____ signals which will travel along the auditory nerve
electrical signals
elastic membrane in cochlear wall
round window
current network of auditory pathways
axons of auditory nerves - medial geniculate nuclei - primary auditory complex
signals are transmitted to both ____ and _____
- ipsilateral
- contralateral
inherently complex in auditory system
subcortical pathways
Receives the majority of its input from medial geniculate nucleus
primary auditory complex
primary auditory complex is located in the ______
temporal lobe
areas of auditory cortex
- 13 separate areas
- core region
- belt
- parabelt areas
band of areas of secondary auditory cortex
belt
areas of secondary auditory cortex outside the belt
parabelt areas
collection of 3 adjacent areas in primary auditory cortex
core region
principles of organization
- organized in functional columns
- tonotopic
- periodotopy
vertically, auditory neurons tend to respond optimally to sounds in the same frequency range
organized in functional columns
organized acc. to temporal components of sound
periodotopy
periodotopy refers to the changes in ____ of sounds in our environment over a period of time
intensity
2 main cortical streams of auditory analysis
- anterior auditory pathway
- posterior auditory pathway
ultimately conducted to the prefrontal cortex and posterior parietal cortex
auditory signals
More involved in identifying sounds (what)
anterior auditory pathway
More involved in locating sounds (where)
posterior auditory pathway
have traditionally been assumed to interact in the association cortex
sensory system
areas of cortex where SS interactions (associations) take place
association cortex
Widely used to investigate SS interactions
functional brain imaging
effects of damage to the auditory system
- auditory cortex damage
- deafness
Major permanent loss of ability to process structural aspects of sounds
auditory cortex damage
- One of most prevalent human disabilities
- Can lead to feelings of social isolation
deafness
______ is rare (only 1%)
total deafness
2 common classes of deafness
- conductive deafness
- nerve deafness
damage to ossicles
conductive deafness
Damage to cochlea or auditory nerve
nerve deafness
major cause of nerve deafness
loss of hair cell receptors
Ringing of the ears
tinnitus
Advanced medical devices designed to provide a sense of sound to individuals with nerve deafness.
cochlear implants
sensations from the body
somatosensation
3 systems of the somatosensory system
- exteroceptive system
- proprioceptive system
- interoceptive system
Monitors conditions inside the body e.g. temperature, blood pressure.
interoceptive system
Has exteroceptors that sense external stimuli
exteroceptive system
Monitors information on the position of the body that comes from receptors in the muscles, joints, and organs of balance (vestibular system)
proprioceptive system
mechanical stimuli
pressure
thermal stimuli
temperature
nociceptive stimuli
pain
cutaneous receptors
- free nerve endings
- pacinian corpuscles
- merkel’s disks
- ruffini endings
Neuron endings with no specialized structures
free nerve endings
free nerve endings are sensitive to ____ and _____
- temperature changes
- pain
Largest and deepest; onion shaped
pacinian corpuscles
Responds to skin indentation (from pressure)
merkel’s disks
Respond to skin stretching and joint activity
ruffini endings
Continuous change in stimulation that enables more awareness towards particular object
stereognosis
stereognosis is identifying objects by ____
touch
2 major somatosensory pathways
- dorsal-column medial-lemniscus system
- anterolateral system
Tends to carry information about touch and proprioception
dorsal-column medial-lemniscus system
Tends to carry information about pain and temp
anterolateral system
somatotopic – organized according to a map of the body surface
primary somatosensory cortex
“little man”
homonculus
refers to the somatotopic map
somatosensory homunculus
input in primary somatosensory cortex is largely ______
contralateral
- Receives most of its input from SI
- Susbtantial input from both sides of the body
secondary somatosensory cortex
somatosensory agnosias
- astereognosia
- asomatognosia
Inability to recognize objects (shape and size) by touch
astereognosia
Inability to recognize parts of one’s own body or the loss of awareness of part of the body
asomatognosia
tendency not to respond to stimuli that are contralateral to a right-hemisphere injury
contralateral neglect
perception of pain
- pain is adaptive
- pain has no clear cortical representation
- pain is modulated by cognition and emotion
Severe chronic pain in the absence of a recognizable pain stimulus
neuropathic pain
neuropathic pain is caused by _____
abnormal activity in the CNS
primary function of chemical senses
to monitor the chemical content of the environment
response of the olfactory system to airborne chemicals that are drawn by inhalation over receptors in the nasal passages
smell
response of the gustatory system to chemicals in solution in the oral cavity
taste
2 adaptive roles of the chemical senses
- evaluation of potential foods
- regulate social interactions
chemicals that influence the physiology and behavior of members of the same species (conspecifics)
pheromones
an integrated sensory impression produced when molecules of food excite both smell and taste receptors
flavor
sensation of smell
olfaction
located in the upper part of the nose, embedded in a layer of mucus-covered tissue
olfactory receptor cells
mucus-covered tissue
olfactory mucosa
discrete clusters of neurons that lie near the surface of the olfactory bulbs
olfactory glomeruli
- Primary olfactory cortex
- Area of medial temporal cortex adjacent to the amygdala
piriform cortex
2 major pathways that leave the amygdala
- limbic pathway
- thalamic-orbitofrontal pathway
Thought to mediate the conscious perception of odors
thalamic-orbitofrontal pathway
Thought to mediate emotional response to odors
limbic pathway
used to refer to the still poorly understood topographic organization of the olfactory bulbs
chemotopic
sensation of taste
gustation
Muscular organ in the mouth; Essential for performing various functions related to speech, taste, chewing, swallowing, and maintaining oral health
tongue
Small, raised structures found on the surface of the tongue that give it its rough texture (in purple); Houses the taste buds (in orange)
papillae
can detect different tastes no matter their location
taste buds
taste buds contain ___ to ___ clusters of taste receptor cells
50 to 100
Specialized cells surrounded by nerve endings
taste receptors
taste receptors are found on the ______ and throughout the ______
- tongue
- gastrointestinal tract
how long does taste receptors survive before being replaced by new cells?
few weeks
3 main types of taste bud cells
- detects bitter, sweet, and umami
- detects sour
- detects salty
metabotropic receptors
- sweet
- umami
- bitter
ionotropic receptors
- salty
- sour
2 m receptors
sweet
about 25 m receptors
bitter
1 m receptors
umami
transduced by 3 ionotropic receptors
salty
mediated by 2 ionotropic receptors
sour
gustatory cortex includes
- primary gustatory cortex
- secondary gustatory cortex
Chemotopically organized
primary gustatory cortex
Responsible for processing and integrating more complex aspects of taste
secondary gustatory cortex
inability to smell
anosmia
Most common neurological cause: a blow to the head that shears the olfactory nerves where they pass through the cribiform plate
anosmia
Inability to taste
ageusia
limited to the anterior two-thirds of the tongue on one side
partial ageusia
The outcome of perception
percept
Prior Experiences affecting Perception
- Knowledge of how mundane things work (environmental learning)
- Knowledge of identity of objects
- Knowledge about temporal order of sensory events
consumes a large proportion of energy used by our brains
perceptual decision making
Mediation towards perceptual decision making is currently associated with the dorsolateral prefrontal cortex and the posterior parietal cortex
neural mechanisms
The product of perception when there is an absence of sensory input.
phantom percepts
presence of a missing limb is still perceived long after it has been lost to injury/amputation
phantom limbs
Individuals experience rich and complex hallucinations
charles bennet syndrome
suggested potential location
claustrum
a claustrum is a structure that is made up of a fine sheet of ____ located just underneath the ___ towards the middle of the brain
- neurons
- cortex
Process where we consciously perceive only a small subset of the the many stimuli available at any one time and largely ignore the rest.
selective attention
Characteristics of Selective Attention
- It improves the perception of the stimuli in focus
- It interferes with the perception of the stimuli not in focus
2 ways of focusing attention
- internal cognitive processes
- external events
internal cognitive processes are also called
endogenous attention
external events are also called
exogenous attention
2 types of attention (based on eye movement)
- covert attention
- overt attention
mediated by top-down (from higher to lower levels) neural mechanisms
internal cognitive processes
mediated by bottom-up (from lower to higher levels) neural mechanisms
external events
A shift of visual attention without any corresponding eye movement
covert attention
A change in visual attention that involves a shift in gaze
overt attention
phenomenon related to attention
- cocktail-party phenomenon
- change blindness phenomenon
Even when you are focusing so intently on one conversation that you are totally unaware of the content of other conversations going on around you, the mention of your name in one of the other conversations will immediately gain access to your consciousness.
cocktail-party phenomenon
the image is composed of two images that alternate with a delay of less than 0.1 second between them
change blindness phenomenon
play major roles in directing top-down attention
- prefrontal cortex
- posterior parietal cortex
selective attention may operate in the principle of a _____
push-pull mechanism
Currently identified as important to attentional gaze
frontal eye field
disorder of attention
simultanagnosia
Difficulty in attending visually to more than one object at a time
visual-simultanagnosia
