behavioral science chapter 2 mcat

sensation

conversion or transduction of physical electromagnetic, auditory, and other information from the internal and external environment into electrical signals within the nervous system

perception

processing of sensory information to make sense of its significance

Sensory receptors

nerves that respond to stimuli and trigger electrical signals

sensory ganglia

collections of cell bodies outside the CNS

projection areas

areas in the brain that further analyze sensory input

Threshold

minimum stimulus that causes a change in signal transduction

absolute threshhold

minimum of stimulus energy that is needed to activate a sensory system

threshold of conscious perception

the minimum stimulus energy that will create a signal large enough in size and long enough in duration to be brought to awareness

difference threshold/just-noticeable difference (jnd)

the minimum difference in magnitude between two stimuli before one can perceive this difference

weber’s law

stats that the jnd for a stimulus is proportional to the magnitude of the stimulus, and that this proportion is constant over most of the range of possible stimuli

signal detection theory

refers to the effects of non-sensory factors, such as experiences, motives, and expectation on perception of stimuli

adaptation

a decrease in response to a stimulus over time

thermoreceptor

respond to changes in temp

hair cell

sense motion of fluid in the inner ear

nocireceptor

sense painful or bothersome physical stimuli

olfactory receptor

respond to volatile compounds;smell

photoreceptors

respond to electromagnetic waves in the visable spectrum (light)

mechanoreceptors

respond to pressure or movement

osmoreceptors

respond to the osmolarity of the blood

taste receptors

respond to dissolved compounds (taste)

eye

an organ specialized to detect light in the form of photons

cornea

gathers and filters incoming light

iris

divides the front of the eye into anterior and posterior chambers. Contains two muscle the dilator and constrictor pupillae which open and close the pupil

pupil

the opening in the center of the iris that controls the amount of light entering the eye.

lens

refracts incoming light to focus it on the retina and is held in place by suspensory ligaments connected to the ciliary muscle

ciliary body

produces aqueous humor

aqueous humor

the clear, watery fluid that fills the anterior and posterior chambers of the eye, located between the cornea and the lens. This fluid is essential for maintaining the shape of the eye, providing nutrients and oxygen to the lens and cornea, and transporting waste products.

rods

detect light and dark

cones

detect colors

macula

corresponds to the central visual field, is a specialized area in the center of the retina responsible for high-resolution, central vision

fovea

center of the macula; contains only cones

parallel processing

how is vision processed? This is the ability to simultaneously analyze and combine the information regarding color form motion and depth

parvocellular cells

detects form. has high spatial resolution and low temporal resolution

magnocellular cells

detects motion, has low spatial resolution and high temporal resolution.

binocular neurons

detects depth

bipolar cells

interneurons that act as a bridge between photoreceptors (rods and cones) and ganglion cells.

amacrine cells

located in the inner plexiform layer, connect to bipolar cells and play a role in detecting motion, regulating light adaptation, and contributing to circadian rhythm. 

horizontal cells

found in the outer plexiform layer, connect to photoreceptor cells (rods and cones) and help modulate their activity, contributing to contrast enhancement and adaptation to different light conditions.

vitreous

a clear, gel-like substance that fills the space between the lens and retina in the eye, making up about two-thirds of the eye's volume. It plays a crucial role in maintaining the eye's shape and providing structural support for the retina.

outer ear

consists of the pinna, external auditory canal. and tympanic membrane

middle ear

consists of ossicles malleus, incus, and staped

inner ear

contains the bony labyrinth

superior olive

localizes the sound

inferior colliculus

involved in the startle reflex

pinna/auricle

the visible, fleshy part of the outer ear. Its main function is to collect and channel sound waves towards the ear canal (external auditory meatus). 

external auditory canal

the tube-like passageway that extends from the outer ear to the tympanic membrane (eardrum). It's a crucial part of the outer ear, playing a role in sound wave transmission and protection

tympanic membrane

a thin, oval-shaped membrane located at the end of the external auditory canal (ear canal). It separates the outer ear from the middle ear. The membrane vibrates in response to sound waves, transferring these vibrations to the ossicles (malleus, incus, and stapes) in the middle ear. 

ossicles

three small bones in the middle ear called the malleus, incus, and stapes. They form a connected chain that transmits and amplifies sound vibrations from the tympanic membrane to the inner ear.

malleus (hammer)

" bone in the middle ear that transmits sound waves to the Incus.

incus (anvil)

one of three small bones (ossicles) in the middle ear. It's located between the malleus (hammer) and the stapes (stirrup). The primary function is to transmit vibrations from the malleus to the stapes

stapes (stirrup)

the innermost of the chain of three ossicles in the middle ear of a mammal having the form of a stirrup, a base occupying the oval window, and a head connected with the incus.

bony labyrinth

the outer, bony casing of the inner ear, housing the membranous labyrinth. It's located within the petrous portion of the temporal bone. is composed of the cochlea, vestibule, and semicircular canals. It's filled with perilymph, a fluid that surrounds the membranous labyrinth. 

membranous labyrinth

a system of fluid-filled ducts and chambers within the inner ear that houses the sensory organs for hearing and balance. It is located within the bony labyrinth and is filled with endolymph, a fluid critical for the inner ear's function. includes the cochlear duct, utricle, saccule, and semicircular ducts. 

cochlea

located in the membranous labyrinth;detects sound

atricle and saccule

located in the membranous labyrinth; detects linear acceleration

semicircular canals

located in the membranous labyrinth; detect rotational acceleration

smell

the detection of volatile or aerosolized chemicals by the olfactory chemoreceptors/nerves in the olfactory epithelium

pheromones

chemicals given off by animals that have an effect on social foraging, and sexual behavior of members of that species

somatosensation

refers to the four touch modalities; pressure, vibration, pain, and temperature

two-point threshold

the minimum distance necessary between two points of stimulation on the skin such that the points will be felt as two distinct stimuli

physiological zero

the normal temperature of the skin to which objects are compared to determine if they feel warm or cold

gate theory of pain

states that pain sensation is reduced when other somatosensory signals are present

kinesthetic sense (proprioception)

the ability to tell where one’s body is in a 3-d space

bottom up (data driven) processing

recognition of objects by parallel processing and feature detection. It is slower but less prone to mistakes

top down (conceptually driven) processing

recognition of an object by memories and expectations, with little attention to detail. Faster but more prone to mistakes

gesalt’s principles

ways 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 groups together

law of good continuation

elements that appear to follow the same pathway tend to be grouped together

subjective contours

the perception of nonexistent edges in figures based on surrounding visual cues

law of closure

when space in enclosed by a group of lines it is perceived as a complete or closed line

law of pragnanz

states that perceptual organization will always be as regular, simple,and symmetric as possible