Weeks 7-12 Flashcards
Sensation
the physical processing of environmental stimuli by the sense organs
Transduction
the conversion of one form of energy to another
Perception
the psychological process of interpreting sensory information
Absolute threshold
the smallest amount of stimulation needed for detection by a sense
Signal detection
- the method we use to measure absolute thresholds
- like someone will listen to increasingly louder tones starting from silence to determine when they begin to hear the sound (their absolute threshold)
Differential threshold
the smallest difference needed in order to differentiate two stimuli (same as just noticeable difference (JND))
Just noticeable difference (JND)
the smallest difference needed in order to differentiate two stimuli (same as differential threshold)
Weber’s Law
- bigger stimuli require larger differences to be notice (EX: it is harder to tell between 10 and 11 pounds than 1 and 2 pounds)
Bottom-up processing
- building up to perceptual experience from individual pieces
- happens with new experiences (like the first time you hear a certain band)
Top-down processing
experience influencing the perception of stimuli
Sensory adaptation
decrease in sensitivity of a receptor to a stimulus after constant stimulation
Retina
cell layer in the back of the eye containing photoreceptors
Binocular disparity
difference in images processed by the left and right eyes
Binocular vision
our ability to perceive 3D and depth b/c of the difference between the images on each of our retinas
Rods
photoreceptors of the retina sensitive to low levels of light. Located around the fovea
Cones
photoreceptors of the retina sensitive to colour. Located primarily in the fovea
Primary visual cortex
area of the cortex involved in processing visual stimuli
Agnosia
loss of the ability to perceive stimuli
Ventral pathway
pathway of visual processing. The ‘what’ pathway.
carries information from the primary visual cortex to the temporal lobe
Dorsal pathway
pathway of visual processing. The ‘where’ pathway.
stretches from the primary visual cortex to the parietal lobe
Dark adaptation
adjustment of eye to low levels of light
Light adaptation:
adjustment of eye to high levels of light
Trichromatic theory
theory proposing colour vision as influenced by three different cones responding preferentially to red, green, and blue
Opponent-process theory
theory proposing colour vision as influenced by cells responsive to pairs of colours
Audition
ability to process auditory stimuli — also called hearing
Sound waves
changes in air pressure. The physical stimulus for audition (hearing).
Pinna
outermost portion of the ear
Auditory canal
tube running from the outer ear to the middle ear
Tympanic membrane
thin, stretched membrane in the middle ear that vibrates in response to sound. Also called the eardrum
Ossicles
a collection of three small bones in the middle ear that vibrate against the tympanic membrane
Cochlea
spiral bone structure in the inner ear containing auditory hair cells – converts sound waves into electrical messages
Auditory hair cells
receptors in the cochlea that transduce sound into electrical potentials
Primary auditory cortex
area of the cortex involved in processing auditory stimuli
Vestibular system
parts of the inner ear involved in balance
Somatosensation
ability to sense touch, pain, and temperature
Mechanoreceptors
mechanical sensory receptors in the skin that respond to tactile stimulation
Primary somatosensory cortex
area of the cortex involved in processing somatosensory stimuli
Somatotopic map
organization of the primary somatosensory cortex maintaining a representation of the arrangement of the body
Nociception
our ability to sense pain
Phantom limb
the perception that a missing limb still exists
Phantom limb pain
pain in a limb that no longer exists
Chemical senses
our ability to process the environmental stimuli of smell and taste
Olfaction (smell)
ability to process olfactory stimuli. Also called smell.
Gustation (taste)
ability to process gustatory stimuli
Odorants
chemicals transduced by olfactory receptors
Olfactory epithelium
organ containing olfactory receptors
Shape theory of olfaction
theory proposing that odorants of different size and shape correspond to different/specialized receptors – not universally accepted
Anosmia
loss of the ability to smell (though it may not be permanent)
Taste receptor cells
receptors that transduce gustatory information
Tastants
chemicals transduced by taste receptors
Flavor
the combination of smell and taste
Multimodal perception
the effects that concurrent stimulation in more than one sensory modality has on the perception of events and objects in the world
Superadditive effect of multisensory integration
the finding that responses to multimodal stimuli are typically greater than the sum of the independent responses to each unimodal component if it were presented on its own
Principle of inverse effectiveness
the finding that, in general, for a multimodal stimulus, if the response to each unimodal component (on its own) is weak, then the opportunity for multisensory enhancement is very large. However, if one component (by itself) is sufficient to evoke a strong response, then the effect on the response gained by simultaneously processing the other components of the stimulus will be relatively small
Pitch
the perceptual correlate of waveform periodicity, or repetition rate (the frequency of the wave)
Timbre
the quality of a sound
Pinna
visible part of the outer ear
Tympanic membrane
ear drum, which separates the outer ear from the middle ear
Cochlea
snail-shell-shaped organ that transduces mechanical vibrations into neural signals; filled with fluid
Basilar membrane
lies along the length of the spiral of the cochlea; vibrates in response to the pressure differences produced by vibrations of the oval window
Organ of Corti
lies on the basilar membrane; runs the entire length of the basilar membrane from its base by the oval window to the apex (the top of the spiral) — includes 3 rows of outer hair cells and one row of inner hair cells — the hair cells sense vibrations through their tiny hairs (called stereocilia) — the outer hair cells mechanically amplify the sound-induced vibrations — the inner hair cells form synapses with the auditory nerve and transduce those vibrations into action potentials (or neural spikes) which are then transmitted along the auditory nerve to higher centers of the auditory pathways (like to the brain to be processed)
Frequency analysis
allows us to hear more than one sound at a time
Masking
the process by which the presence of one sound makes another sound more difficult to hear
Information masking
another form of masking that cannot be accounted for with explanations in terms of interactions with the cochlea — little is known about the causes of informational masking
Interaural time differences (ITD)
differences (usually in time or intensity) between the two ears
ex: we know a sound is coming from the left because the sound reaches the left ear quicker than the right ear
Interaural level differences (ILDs)
differences (usually in time or intensity) between the two ears
ex: if a sound is presented to the left ear, it will be slightly higher than in the right ear by a small amount
Pain
Defined as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage,” according to the International Association for the Study of Pain.
Interoception
the sense of the psychological state of the body. Hunger, thirst, temperature, pain, and other sensations relevant to homeostasis. Visceral input such as heart rate, blood pressure, and digestive activity give rise to an experience of the body’s internal states and physiological reactions to external stimulation. This experience has been described as a representation of “the material me,” and it is hypothesized to be the foundation of subjective feelings, emotion, and self-awareness
Exteroception
the sense of the external world, of all stimulation originating from outside our own bodies
Cutaneous senses
the senses of the skin: tactile, thermal, pruritic (itchy), painful, and pleasant
Nociception
the neural process of encoding noxious stimuli, the sensory input from nociceptors. Not necessarily painful, and crucially not necessary for the experience of pain
Transduction
The mechanisms that convert stimuli into electrical signals that can be transmitted and processed by the nervous system. Physical or chemical stimulation creates action potentials in a receptor cell in the peripheral nervous system, which is then conducted along the axon to the central nervous system.
Mechanoreceptors
responds to mechanical stimuli, like stroking, stretching, or vibration of the skin; one of the 3 main groups of receptors in our skin
Thermoreceptors
responds to hot or cold temps; one of the 3 main groups of receptors in our skin
Chemoreceptors
responds to certain types of chemicals either applied externally or released within the skin; one of the 3 main groups of receptors in our skin
Nociceptors
High-threshold sensory receptors of the peripheral somatosensory nervous system that are capable of transducing and encoding noxious stimuli. Nociceptors send information about actual or impending tissue damage to the brain. These signals can often lead to pain, but nociception and pain are not the same.
A-fibers
fast-conducting sensory nerves with myelinated axons. Larger diameter and thicker myelin sheaths increases conduction speed. Aβ-fibers conduct touch signals from low-threshold mechanoreceptors with a velocity of 80 m/s and a diameter of 10 nanometers; Aδ-fibers have a diameter of 2.5 nanometers and conduct cold, noxious, and thermal signals at 12 m/s. The third and fastest conducting A-fiber is the Aα, which conducts proprioceptive information with a velocity of 120 m/s and a diameter of 20 nanometers
Somatosensory cortex
Consists of primary sensory cortex (S1) in the postcentral gyrus in the parietal lobes and secondary somatosensory cortex (S2), which is defined functionally and found in the upper bank of the lateral sulcus, called the parietal operculum. Somatosensory cortex also includes parts of the insular cortex.
Somatotopically organized
When the parts of the body that are represented in a particular brain region are organized topographically according to their physical location in the body.
C-pain or Aδ-fibers
C-pain fibers convey noxious, thermal, and heat signals
C-fibers
slow-conducting unmyelinated thin sensory afferents with a diameter of 1 nanometer and a conduction velocity of approx. 1 m/s. C-pain fibers convey noxious, thermal, and heat signals
C-tactile fibers
C-tactile fibers convey gentle touch, light stroking
Social touch hypothesis
which proposes that C-tactile fibers form a system for touch perception that supports social bonding. OR: Proposes that social touch is a distinct domain of touch. C-tactile afferents form a special pathway that distinguishes social touch from other types of touch by selectively firing in response to touch of social-affective relevance; thus sending affective information parallel to the discriminatory information from the Aβ-fibers. In this way, the socially relevant touch stands out from the rest as having special positive emotional value and is processed further in affect-related brain areas such as the insula.
Spinothalamic tract
Runs through the spinal cord’s lateral column up to the thalamus. C-fibers enter the dorsal horn of the spinal cord and form a synapse with a neuron that then crosses over to the lateral column and becomes part of the spinothalamic tract.
Descending pain modulatory system:
a top-down pain-modulating system able to inhibit or facilitate pain. uses ON- and OFF-cells to inhibit or facilitate nociceptive signals at the spinal dorsal horn.
can regulate how much pain/nociceptive signal reaches the brain
analgesics (pain relievers) like morphine relieve pain via this circuit
Analgesics/Analgesia
pain relief
Placebo effect
Effects from a treatment that are not caused by the physical properties of a treatment but by the meaning ascribed to it. These effects reflect the brain’s own activation of modulatory systems, which is triggered by positive expectation or desire for a successful treatment. Placebo analgesia is the most well-studied placebo effect and has been shown to depend, to a large degree, on opioid mechanisms. Placebo analgesia can be reversed by the pharmacological blocking of opioid receptors. The word “placebo” is probably derived from the Latin word “placebit” (“it will please”).
Endorphin
an endogenous morphine-like peptide that binds to the opioid receptors in the brain and body; synthesized in the body’s nervous system – relieve stress and pain
Allodynia
pain due to a stimulus that does not normally provoke pain, ex: when a light, stroking touch feels painful
Noxious stimuli
A stimulus that is damaging or threatens damage to normal tissues.
Chronic pain
persistent or recurrent pain, beyond usual course of acute illness or injury; sometimes present without observable tissue damage or clear cause
Sensitization
Increased responsiveness of nociceptive neurons to their normal input and/or recruitment of a response to normally subthreshold inputs. Clinically, sensitization may only be inferred indirectly from phenomena such as hyperalgesia or allodynia. Sensitization can occur in the central nervous system (central sensitization) or in the periphery (peripheral sensitization).
Phantom pain
Pain that appears to originate in an amputated limb.
Electromagnetic energy
pulses of energy that can carry information from place to place
Wavelength
the distance between one wave peak and the next
Visible spectrum
the part of the electromagnetic spectrum that our eyes detect (only the range from about 400 to 70 billionths of a meter)
Cornea
a clear covering that protects the eye and begins to focus the incoming light
Pupil
a small opening in the center of the eye
Iris
the coloured part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity
Lens
a structure that focuses the incoming light on the retina
Retina
the layer of tissue at the back of the eye that contains photoreceptor cells
Visual accommodation
the process of changing the curvature of the lens to keep the light entering the eye focused on the retina – occurs as our eyes move from near objects to distant ones
Nearsighted
when the focus is in front of the retina
Farsighted
when the focus is behind the retina
Optic nerve
a collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain
Rods
visual neurons that specialize in detecting black, white, and grey colours
Cones
visual neurons that are specialized in detecting fine detail and colours
Fovea
the central point of the retina
Blind spot
a hole in our vision because there are no photoreceptor cells at the place where the optic nerve leaves the retina
Feature detector neurons
specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus
Hue
the shade of a colour
Trichromatic colour theory
the colours we see depends on the mix of the signals from the three types of cones
Colour blindness
the inability to detect green and/or red colours
Opponent-process colour theory
proposes that we analyze sensory information not in terms of three colours but rather in three sets of “opponent colours”: red-green, yellow-blue, and white-black
Gestalt
a meaningfully organized whole
Visual cliff
a mechanism that gives the perception of a dangerous drop-off, in which infants can be safely tested for their perception of depth
Depth cues
messages from our bodies and the external environment that supply us with information about space and distance
Binocular depth cues
depth cues that are created by retinal image disparity — that is, the space between our eyes — and which thus require the coordination of both eyes
Convergence
the inward turning of our eyes that is required to focus on an objects that are less than 50 feet away from us
Accommodation
helps determine depth by changing the curvature of the lens – same as visual accommodation
Monocular depth cues
depth cues that help us perceive depth using only one eye
Beta effect
the perception of motion that occurs when different images are presented next to each other in succession