Sensation and PErception Flashcards
Sensory Receptors
Nerves that respond to stimuli and trigger electrical signals
Sensory Ganglia
Collections of cell bodies outside the CNS associated with sensory neurons
Projection Areas
Areas in brain where sensory stimuli are transmitted to and further analyzed
Threshold
Minimum stimulus that renders a difference in perception
Absolute threshold
The minimum of stimulus energy that is needed to activate a sensory system
Threshold of conscious perception
Minimum of stimulus energy that will create a signal large enough in size and long enough in duration to be brought into awareness
Difference threshold or just-noticeable difference (jnd)
Minimum difference in magnitude between 2 stimuli before one can perceive this difference
Weber’s law
States that there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus
Adaptation
Decrease in response to a stimulus over time
Cornea
Gathers and filters incoming light
Iris
Contains 2 muscles that open and close the pupil, plus divides the front of the eye into anterior and posterior chambers
Lens
Refracts incoming light to focus it on the retina and is held in place by suspensory ligaments connected to the ciliary muscle (under parasympathetic control); this change of shape is called accommodation
What does the cilia body produce?
Aqueous humour that bathes the front part of the eye –> drains into the canal of Schlemm
The retina contains what 2 light-detecting structures?
Rods and Cones
Rods
Detects light and dark; have low sensitivity to details but permit light vision
Cones
Comes in 3 forms (short, medium, and long-wavelength) to detect colours.
Which part of the retina contains mostly cones?
The macula, which corresponds to the central visual field –> in the center of the mucula is the fovea, which contains ONLY cones (most sensitive to normal daylight vision)
What do rods and cones synapse on?
Bipolar cells, which then synapse on ganglion cells
What do horizontal and amacrine cells do?
Integrate signals from multiple retinal cells in the same area and perform edge-sharpening on vision
What supports the bulk of the eye?
The vitreous humour on the inside and the sclera and choroid on the outside
Name the parts in order of the visual pathway
cornea –> pupil –> lens –> vitreous –> retina (rods and cones –> bipolar cells –> ganglion cells) –> optic nerve –> optic chiasm –> optic tract –> lateral geniculate nucleus in thalamus –> radiations through temporal and parietal lobes –> visual cortex in occipital lobe
Optic chiasm contains fibers crossing from the nasal side of the retina of both eyes.
Visual radiations run through temporal and parietal lobes
Visual cortex is in the occipital lobe
There are also inputs into the superior colliculus
What type of cells detect shape
Parvocellular cells, which have high spatial resolution and low temporal resolution
What type of cells detect motion
Magnocellular cells, which have low spatial resolution and high temporal resolution
3 divisions of the ear?
Outer, middle, and inner
Outer ear
Consists of the pinna (auricle), external auditory canal, and tympanic membrane
Middle ear
Consists of ossicles: malleus (hammer), incus (anvil), and stapes (stirrup). The middle ear is connected to the nasal cavity by the Eustachian tube.
Inner Ear
Contains the bony labyrinth, which contains the cochlea, vestibule, and semicircular canals. These structures are continuous with each other and are mostly filled by the membranous labyrinth
What fluid suspends the membranous labyrinth in the bony labyrinth
Perilymph; simultaneously transmits vibrations from the outside world and cushions the inner ear structures
What bathes the membranous labyrinth
Potassium-rich endolymph
What are the parts of the auditory pathway
Pinna –> external auditory canal –> tympanic membrane –> malleus –> incus –> stapes –> oval window –> perilymph in cochlea –> basilar membrane –> hair cells –> vestibulocochlear nerve –> brainstem –> medial geniculate nucleus (MGN) of thalamus –> auditory cortex (temporal lobe)
Sound info also projects to the superior olive (localizes sound) and inferior colliculus
What is smell?
The detection of volatile or aerosolized chemicals by the olfactory chemoreceptors (olfactory nerves) in the olfactory epithelium.
What is the olfactory pathway
nostril –> nasal cavity –> olfactory chemoreceptors (olfactory nerves) on olfactory epithelium –> olfactory bulb –> olfactory tract –> higher-order brain regions, including limbic system
What is taste?
The detection of dissolved compounds by taste buds in papillae
What are the 5 modalities of taste
Sweet, sour, salty, bitter, and umami (savoury)
What does somatosensation refer to
The four touch modalities: pressure, vibration, pain, and temperature
Two-point threshold
The minimum distance necessary between 2 points of stimulation on the skin such that the points will be felt as two distinct stimuli
Gate theory of pain
States that pain sensation is reduced when other somatosensory signals are present
Kinesthetic sense (propioception)
Refers to the ability to tell where one’s body is in 3-dimensional space.
Parallel Processing
The ability to simultaneously analyze and combine information regarding color, shape, and motion (correlate in neuroscience is feature detection) i.e. a flying red bird
Bottom-up (data-driven) processing
Refers to recognition of objects by parallel processing and feature detection –> slower, but less prone to mistakes. Brain essentially takes individual sensory stimuli and combines them together to create a cohesive image before determining what the object is
Top-down (conceptually driven) processing
Refers to recognition of an object by memories and expectations, with little attention to detail –> faster, but more prone to mistakes
What is perceptual organization
Refers to our synthesis of stimuli to make sense of the world, including integration of depth, form, motion, and constancy
Gestalt principles
Ways that the brain can infer missing parts of a picture when a picture is incomplete
Law of Proximity
Elements close to one another tend to be perceived as a unit
Law of Similarity
Objects that are similar appear to be grouped together
Law of Good Continuation
Elements following the same path tend to be grouped together
Subjective contours
Perception of nonexistent edges in figures based on surrounding visual cues
Law of closure
A space is enclosed by a group of lines is perceived as a complete or closed line
Law of Pragnanz
Perceptual organization is as regular, simple, and symmetric as possible
Photoreceptors
Respond to electromagnetic waves in the visible spectrum (sight)
Hair cells
Respond to movement of fluid in the inner ear structures (hearing, rotational and linear acceleration)
Nocireceptors
Respond to painful or noxious stimuli (somatosensation)
Thermoreceptors
Respond to changes in temperature (thermosensation)
Osmoreceptors
Respond to the osmolarity of blood (water homeostasis)
Olfactory receptors
Respond to volatile compounds (smell)
Taste receptors
Respond to dissolved compounds (Taste)
Psychosocial discrimination testing
A participant is presented with a stimulus that is varied slightly, and then is asked to identify whether there is a difference in the second stimulus
Signal Detection Theory
Focuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context.
Response Bias
Refers to the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors
Catch trials
Trials in signal detection theory in which the signal is presented
Noise trials
Trials in signal detection theory in which the signal is not presented
Sclera
The “white” of the eye, a thick structural layer that covers most of the exposed portion of the eye
What 2 sets of blood vessels supply the eye with nutrients
The choroidal and retinal vessels
Retina
Innermost layer of the eye, which contains the actual photoreceptors that transduce light into electrical info the brain can process
2 muscles of the iris
dilator pupillae and constrictor pupillae
Dilator pupillae
Opens the pupil under sympathetic stimulation
Constrictor pupillae
Constricts the pupil under parasympathetic stimulation
Vitreous
A transparent gel that supports the retina behind the lens
Is the number of receptors converging onto an individual ganglion cell smaller for rods or cones
Cones; thus color vision has a greater sensitivity to fine detail than black and white vision
Function of pinna/auricle
Channels sounds waves into the external auditory canal
External auditory canal
Directs sound waves to the tympanic membrane (eardrum)
Tympanic membrane
Vibrates in phase with the incoming sound waves
Cochlea
A spiral-shaped organ divided into 3 parts called scalae
What is the middle scalae called and what does it do
Called organ of Corti, houses the actual hearing apparatus and rests on a thin, flexible membrane called the basilar membrane. Composed of thousands of hair cells which are based in endolymph
What do the other two scalae besides the organ of Corti do
They are filled with perilymph and surround the hearing apparatus and are continuous with the oval and round windows of cochlea
Vestibulocochlear nerve (auditory nerve)
Physical stimulus on hair cells are converted to electrical signals, which this nerve carries to CNS
Vestibule
Refers to the portion of the bony labyrinth that contains the utricle and saccule
Utricle and saccule
Sensitive to linear acceleration; helps determine one’s orientation in 3-D space. They contain otoliths, modified hair cells that resist motion when the body accelerates…send signals to the brain
Semicircular canals
Sensitive to rotational acceleration (there are 3). They each end in a swelling called an ampulla, where hair cells are located. When the head rotates, endolymph in the semicircular canal resist this motion, bending the underlying hair cells, which sends a signal to the brain.
How do hair cells work?
As vibrations reach the basilar membrane underlying the organ of Corti, the stereocilia adorning the hair cells begin to sway back and forth within the endolymph; causes the opening of ion channels, which cause a receptor potential.
What is the accepted theory on sound perception
Place Theory; states that the location of a hair cell on the basilar membrane determines the perception of pitch when that hair cell is vibrated
Pacinian corpuscles
Respond to deep pressure and vibration
Meissner corpuscles
Respond to light touch
Merkel cells (discs)
Respond to deep pressure and texture (think of bumpy massage discs)
Ruffini endings
Respond to stretch
Free nerve endings
Respond to pain and temperature
Physiological zero
The normal temperature of the skin; to which temperature is compared to
Depth perception
Relies on both monocular and binocolur cues
Constancy
Refers to the idea that we perceive certain characteristics of objects to remain the same, despite differences in the environment
