Psych/Soc 1 Flashcards
Types of sensory receptors
- Electromagnetic receptor
- Thermoreceptor
- Mechanoreceptor
- Chemoreceptor
- Nociceptor
- Baroreceptor
Electromagnetic receptor
Sense EM waves (such as light).
Ex: photoreceptors in the eye
Thermoreceptor
Sense temperature (cold or hot) Ex: found in the skin
Mechanoreceptor
Sense a mechanical disturbance, such as stretching or compression.
Ex: Pacinian corpuscles, Ruffini endings/corpuscles, and Meissner’s corpuscles in skin; auditory and vestibular hair cells
Chemoreceptor
Detect chemicals and their levels.
- Taste buds and olfactory nerves
- Also sense changes inside the body such as fluid osmolarity, pH levels, CO2 levels, etc.
Nociceptor
Sense pain.
-Found in the skin and throughout most body tissues
Baroreceptor
Sense pressure.
-Found in the aortic arch and sense arterial pressure
Sensory Pathways
- Sensory information sent from the PNS (detected) to the CNS.
- In the CNS, interpretation of the stimulus occurs
- Most senses are contralateral (exception is hearing which is both ipsilateral and contralateral).
- 2 types of pathways (conscious and subconscious)
In the CNS, interpretation of stimulus occurs based on…
1) which neurons sent the impulse/where they synapse (information about sensory modality)
2) Frequency of the action potentials (codes for signal intensity)
3) Duration of continuous firing (codes for stimulus exposure)
Conscious perception
PNS -> spinal cord -> thalamus -> cerebral cortex
- Sensory information enters consciousness
- Olfactory information doesn’t go through the thalamus.
Subconscious perception
PNS -> spinal cord -> cerebellum
-Sensory information doesn’t enter consciousness
Psychophysics
Looks at the relationship between physical stimuli and the resultant sensation and perceptions
Absolute threshold
The level of a stimulus at which it will be detected 50% of the time
Difference threshold
How different two stimuli need to be for an individual to be able to recognize that they aren’t the same (at least 50% of the time0
-Aka Just Noticeable Difference (JND)
Weber’s Law
The size of the JND is a constant proportion of the original stimulus value.
-The value of the proportion varies across sensory modalities, stimuli, and tasks.
Signal detection theory
Attempts to assess/quantify when an individual will detect the presence of a stimuli against all other background “noise”
HIT
Signal present, subject responds “yes”
Type 1 error
False positive.
-Signal absent, subject responds “yes”
Type II error
False negative
Signal present, subject responds “no”
Correct rejection
Signal absent, subject responds “no”
Sensory adaptation
Change in the responsiveness of one’s sensory system to a constant stimulus.
- Not the same as habituation, which is a type of “learning” and involves changes in the physiological, emotional, or behavioral response to a stimulus.
- Receptors may be fast-adapting, slow-adapting, or non-adapting (nociceptors)
Perception
The process of becoming aware of, organizing, and interpreting sensory information.
- Dependent not only on the sensory information but also the individual’s memory, past experiences, expectations, and attention.
- Perception occurs through both bottom-up and top-down processing.
Bottom-up processing
Using the sensory information to compile a cohesive understanding of the whole.
-“data-driven”
Top-down processing
Applying one’s own knowledge, experiences, and expectations in interpreting and understanding the sensory information
- Applying higher level information to lower level (more basic) information.
- Often occurs when the sensory information is vague or incomplete.
Parallel processing
The ability of the brain to simultaneously process different streams of sensory information
Gestalt Principles
Different rules that describe how people tend to organize, group, and perceive sensory stimuli (usually visual)
-“the whole exceeds the sum of its parts” -> what we perceive is based not only on the sensory input but also on the innate tendency of our brain to organize the stimuli in a certain way.
Figure/ground
We tend to pick out and focus on one figure/object, perceiving it as separate from the background of an image.
Law of Proximity
Elements that are close together tend to be perceived as a unified group.
-Items that are close to each other tend to be grouped together, whereas items further apart are less likely to be grouped together
Law of closure
If there is a break in the object, we perceive the object as continuing in a smooth pattern
Law of similarity
Elements that are similar to each other tend to be perceived as a unified group.
-Similarity can refer to any number of features, including color, orientation, size, or indeed motion
Law of connectedness
Elements that are connected to each other using colors, lines, frames, or other shapes are perceived as a single unit when compared with other elements that are not linked in the same manner.
Law of Continuity
There is a tendency to perceive a line continuing its established direction. If a figure is split into two parts, then the figure is seen as the whole instead of 2 separate smaller figures.
Cornea
Clear tissue in front of the eye that acts like a lens to focus and refract light
Iris
Changes the size of the pupil to control how much light gets into the eye.
-Colored part of the eye
Lens
Region through which light enters the eye.
Lens
Focuses light onto the retina; biconvex shape refracts light.
-Curvature of the lens is constantly changing
Accommodation
The curvature of the lens is constantly changing due to ciliary muscles which are under parasympathetic control
Sclera
White and protective outer layer of the eye
Retina
Layer of the eye onto which light is projected and detected by photosensitive cells (Rods and cones)
Fovea
Region of the retina with the highest visual acuity; high concentration of cones.
Visual acuity
the clarity and sharpness of vision
Optic Nerve
A bundle of the axons of ganglion cells.
-Exits the back of the eye at the optic disk (blind spot because no photoreceptors)
Myopia
- Near-sightedness
- Lens too curved so too much refraction of light
- Correct with concave lens
Hyperopia
- Far-sightedness
- Lens not curved enough so too little refraction of light
- Correct with convex lens
Rods
- Detect light at lower levels and motion.
- Responsible for vision in the dark.
- Only black and white; don’t detect color
- Low spatial acuity
Cones
- Detect bright light and responsible for color vision
- High spatial acuity
- 3 types of cones- “green”, “red”, and “blue” -> named based on the range of frequencies that they detect
Opsin proteins
- Both rods and cones have opsin proteins
- Enable the photon to be converted into a chemical signal
- Bound to retinal molecule which undergoes isomerization from 11-cis retinal to all-trans retinal -> opsin GPCR changes conformation -> signal transduction cascade
Phototransduction pathway: Light present
1) Photon converts 11-cis retinal to all trans retinal
2) conformational change of opsin GPCR
3) PDE activated and breaks down cGMP
4) Na+ channels close
5) Rods and cones hyper polarize and stop releasing glutamate
6) bipolar cells depolarize
7) ganglion cells depolarize
8) action potential sent along optic nerve to the brain
Phototransduction Pathway: No light
1) cGMP levels are high
2) Na+ channels kept open
3) rod/cone cells are depolarized
4) glutamate released to bipolar cells
5) glutamate inhibits (hyper polarizes) bipolar cells
Cells involved & conduction pathway
1) Light penetrates through the cells of the retina to reach the rods and cones, where the EM waves are detected
2) Signal sent from rods and cones -> bipolar cells -> ganglion cells -> optic nerve
3) At the optic chiasm, axons of the optic nerve arrange themselves so that axons that originated in left visual field of both retinas and up in the right brain hemisphere and vice versa
4) Axons synapse in the LGN of the thalamus
5) Signal sent from LGN to the primary visual cortex of the occipital lobe
6) Information sent from primary visual cortex to higher visual processing in other regions of the occipital cortex
Feature detection
Attempts to understand how the various and diverse features of an image are extracted and compiled to form a cohesive and useful understanding.
- Proposed idea was that these different features of the image are processed in parallel and eventually these details are compiled in occipital cortex to form a cohesive image.
- Uses parallel process and is an example of bottom-up processing
feature detectors
neurons that selectively fire in response to specific features on an image (color, brightness, edges, movement, angles, etc.)
Motion Perception
Retinal ganglion cells can encode motion.
Some ganglion cells fire preferentially to movement in certain direction.
-They can detect this because 1 ganglion cell receives into from multiple bipolar cells which received info from many rods/cones (can only signal light or no light and color)
Depth perception
We must be able to extract depth using various cues in order to perceive a 3D image when the information from the retina is in a 2D image.
-We use binocular cues (information from both eyes) and monocular cues (information from one eye)
Binocular Cues
-Retinal disparity: compare images from the right and left retinas -> the more different they are, the closer an object is to you
Convergence: how much your eyes must converge towards the midline of your face to focus on an image
Monocular Cues
- Relative size: one adult much smaller than another is farther away
- Relative motion: closer objects move faster
- Motion parallax: as you move, if the image moves a lot in your visual field then its farther
- Perspective: parallel lines converge at a distance
- Accommodation of ciliary muscles
- Interposition: one object that blocks another is closer
- Texture gradient: texture more clear on closer objects
- Light and shadows
Outer ear
Auricle/pinna + auditory canal
-Captures sound waves and directs them into the ear
Middle ear
Tympanic membrane (eardrum) + ossicles
- Tympanic membrane vibrates when sound waves arrive
- Ossicles are the smallest bones of the body; there are 3: malleus, incus, stapes
Vibrations from the tympanic membrane go where?
Vibrations from tympanic membrane passed from malleus -> incus -> stapes -> inner ear
Inner ear
Oval window, cochleae filled with fluid (endolymph), organ of Corti, hair cells, tectorial membrane, and basilar membrane (plus the vestibular system)
- Stapes transmits the vibrations to the oval window, which transmits them through the endolymph
- Pressure waves in the endolymph transmitted to hair cells (auditory sensory receptors)
Auditory pathway
1) Pressure waves in endolymph cause the basilar membrane (where hair cells are located) to vibrate
2) hair cells move while the tectorial membrane doesn’t
3) sterocilia are dragged across the tectorial membrane and bend relative to the hair cells
4) mechanically-gated ion channels open (K+ and Ca2+ enter)
5) hair cells depolarize (no AP) and release neurotransmitters onto fibers of the auditory nerve
6) AP fired in auditory nerve fibers
7) impulse sent to auditory cortex in temporal lobe (by way of the thalamus)
Frequency of sound
- Frequency of sound encoded by region of the cochlea where hair cells are firing
- Closer to apex => lower frequency
- Loudness of sound encoded by frequency of AP firing
Vestibular sense
Part of the inner ear that senses motion, balance, and spatial orientation
- The orientation of our body with respect to gravity
- Contributes to our kinesthetic sense
Semi-circular canals
- 3 round interconnected tubes that are oriented at right angles to each other; filled with endolymph
- Each canal contains a bundle of hair cells, which have their cilia embedded in a gelatinous cupula
- Certain body movements result in movement of the endolymph in a given direction deflecting the cupula and bending the ciliary within -> impulse is sent to the brain
- These detect rotational movement and acceleration of the head
Otolithic organs
Comprised of 2 chambers, the utricle and saccule
- Each has hair cells with their cilia embedded in gelatinous membrane.
- Membrane is weighted down with CaCO3 crystals -changes in acceleration of the head results in these crystals bearing down more on the membrane -> cilia bend and an impulse is sent to the brain
- Sense linear acceleration
Somatosensation
The sense of touch, pain, and temperature at the surface of the body.
-Information about touch is sent to the somatosensory cortex in the brain.
Temperature
-Sensed by thermoreceptors in the skin
Pain
Sensed by free nerve endings (nociceptors) in the skin
Pacinian Corpuscles
Touch
-Pressure and vibration
Meissner’s corpuscles
Touch
-Texture and vibration
Merkel’s disks
Touch
-Touch and pressure
Ruffini’s corpuscles
Touch
-Stretching of skin
Touch
Touch receptors differ in their speed of adaptation, size of receptive field, and location (depth) in the skin
Taste (gustation)
Taste buds on the tongue contain many taste receptor cells.
-Info is sent via cranial nerves to the temporal and parietal lobes
Taste receptors
chemoreceptors that bind to chemicals form food.
-Receptors detect a specific taste: sour, sweet, salty, bitter, or umami
GPCR signal transduction mechanism
Bitter, sweet, and umami receptors use this.
1) Ligand (food chemical indicative of that specific taste) binds to a receptor
2) Secondary messenger cascade
3) Cell depolarizes and send AP
Salty and sour receptors
Have ion channels
Smell (olfaction)
1) olfactory bulb
2) Mitral Cells
3) Bone
4) Nasal epithelium
5) Olfactory glomerulus
6) Olfactory receptor neurons
- Olfaction and gustation interact- the combined information gives of our full sense of taste and smell.
- Olfaction is the only sense that isn’t routed through the thalamus.
- Olfactory bulb is a part of the limbic system. Smell tightly linked to memory and emotion.
- Olfactory information is mainly processed by the temporal lobe.
Mitral cells
receive information from olfactory receptor neurons ; axons of mitral cell form the olfactory tract -> brings information to many different brain regions including the entorhinal cortex and the amygdala
Nasal epithelium
lines of the roof of the nasal cavity
Olfactory glomerulus
cluster of nerve findings
Olfactory receptor neurons
chemoreceptors embedded in nasal epithelium; detect chemicals (odorants) that bind to receptors
Pheromones
chemical messengers that trigger a social response in members of the same species. Humans: many pheromones involved in sexual behavior
Kinesthetic Sense
Awareness of and ability to control our own bodies’ movements; relies on information from the vestibular sense and proprioception.
- Enables us to coordinate movement and control physical activities
- Component of muscle memory
Proprioception
Awareness of the position of one’s body in space
Golgi tendon organs
Detect muscle tension; located in tendons
Muscle spindle fibers
Detect muscle stretch (length); located in muscles
Join capsule receptors
Located in synovial joins and contain a collection of different sensory receptors that convey information about join strain, position, and movement.
-Free nerve endings, Ruffini endings, Golgi type endings. etc.
