B&B Exam 3

Bipolar neurons and ganglion neurons

located in the inner neural layer of the eyeball. These two kinds of nerve cells combine to produce a pathway for light

bipolar neurons

HAs synapses both ends, forming a bridge. on one end it synapses with a photoreceptor, and at the other end it synapses with a ganglionic neuron, which goes on to from the optic nerve

we perceive long waves with low frequencies as…

red-ish colors

when are hues perceived as dull and mute?

if the wave is moving at a lower amplitude

when are hues perceived as bright?

when the wave is moving at a greater amplitude

receptor

cell, often specialized neuron, suited by its structure to respond to specific form of energy, such as vibration of sound

sensation

acquisition of sensory information

perception

interpretation of sensory information once it’s coded by neural impulses

Cochlea

where auditory stimulus is converted into neural impulses

Adequate stimulus for audition

vibration in a conducting medium (usually air but \n occasionally water or even cranial vibration)

Frequency

number of cycles or waves of alternating compression and decompression of vibrating medium per second

Intensity

physical energy in a sound (affects loudness)

Why are loudness and sound intensity not the same thing

Our body’s precieve sound differently depending on multiple factors

Pure tones

waveforms with a very regular (sine) wave, which have only one frequency

Complex sounds

sounds that mix several frequencies, showing combination of frequencies and amplitudes

Pinna

flap of the ear that graces the side of the head, also called the outer ear. Amplifies sounds.

Tympanic membrane

very thin membrane stretched across end of the auditory canal (ear drum). Transmits sound energy through ossicles

Ossicles

Tiny bones in the middle ear that operate in lever fashion to transfer vibrations from tympanic membrane to the cochlea.

Malleus, Incus, stapes

Operate in a lever fashion to transfer vibrations from ear drum to inner ear. Different names for the different shapes they make up

Eustachian tube

middle ear structure that connects middle ear to the back of the mouth, equalizing air pressure of middle ear with the outside world.

Cochlear canal

location of auditory receptors which vibrate due to activity in vestibular and tympanic canals. one of 3 fluid filled chambers.

Organ of Corti

sound-analyzing structure that rests on basilar membrane which consists of four rows of specialized cells called hair cells

basilar membrane

membrane that supports organ of Corti

Tectorial membrane

membrane above hair cell that attach to neurons that transmit impulses.

Inner hair cells

sensory cells that receive 90–95% of auditory neurons

Outer hair cells

increase cochlea’s sensitivity both by amplifying its output and sharpening frequency tuning at location of peak vibration.

Inferior colliculi

involved in sound localization

Tonotopically organized

type of organization in which neurons from adjacent receptor locations project to adjacent cells

Dorsal stream

takes auditory info from inferior colliculi to the thalamus, then to auditory lobe. Then from this path it goes through the parietal area where other sensory info is processed. Then goes to the frontal lobe where sound can be processed on a more complex level. Helps identify where a sound is

Ventral stream

Helps identify what a sound is by connecting to areas like hippocampus where we can use past experience to recognize sounds.

Frequency theory

The whole basilar membrane vibrates at the frequency of the sound

Telephone theory

early form of frequency theory developed by William Rutherford that posited individual neurons in auditory nerve fired at same frequency as rate of vibration of sound source

Volley theory

neurons take turns firing while others are in the refractory period

Place theory

different pitches activate different places on the cochleas basilar membrane

Frequency-place theory

combination theory stating frequency following by individual neurons accounts for frequencies up to about 200 Hz and all remaining frequencies are represented by place of greatest activity

Cocktail party effect

ability to sort out and focus on meaningful auditory messages from complex background of sounds

Auditory object:

sound we identify as distinct from other sounds

What are the three cues that assist in rapid and accurate judgments sound location

Interaural level difference, Interaural timing difference, Head-related transfer function (HRTF)

Head-related transfer function (HRTF)

frequency of sound wave is modified by the way the wave hits our pinna.

Interaural timing difference

a sound directly to person’s left or right takes about 0.5 milliseconds to travel additional distance to second ear. Locating sounds because we hear it in one ear sooner vs the other.

Interaural level difference

locating sounds caused when sound interference of head causes near ear to receive more intense sound. Locating sounds because we hear it at an a more intense volume in one ear vs the other.

Echolocation

a sort of sonar typically used by animals like bats, dolphins, and cave-dwelling birds, animals use sound localization to avoid obstacles in total darkness

Language

structured system of communication with common set of grammatical and organizational rules

Grammar

consistent set of language rules

aphasia

language impairment caused by damage to the brain

Broca’s aphasia

language impairment caused by damage to Broca’s area and surrounding cortical and subcortical areas. Non-fluent speaking, Anomia (inability to find the right words), mispronunciation of words, lack of grammer

Wernickes aphasia

language impairment where person has difficulty understanding and producing spoken and written language.

Wernicke-Geschwind theory

idea that visual information must be converted to auditory form for processing arose in part from fact that language evolved before writing and Wernicke’s area was believed to operate in an auditory fashion

Alexia

inability to read

Agraphia

inability to write

Angular gyrus

brain pathway that connects visual projection area with \n auditory and visual association areas in temporal and parietal lobes

Dyslexia

impairment of reading

Phonological hypothesis

predominant understanding that dyslexia is due to a disability in learning grapheme-phoneme correspondences

Planum temporale

location of the posterior part of Wernicke’s area, typically about 13% larger in left hemisphere than in right

Prosody

use of intonation, emphasis, and rhythm to convey meaning in speech

How many light receptors are in the human eye?

97 million

Electromagnetic spectrum

variety of energy forms, ranging from gamma rays at one extreme of frequency to the radiations of alternating current circuits at the other

Sclera

white, opaque outer covering with transparent cornea

How do pupils work?

Muscular iris contracts and expands to allow light to enter

short waves at high frequencies are seen as…

blue-ish colors

the frequency of a light wave determines its….

hue

lens

focuses light rays onto retina

Accommodation

process in which ciliary muscles attached to the lens of the eye contract to make lens rounder, allowing the eye to focus on a near object

Retina

light sensitive tissue at the rear of the eye, made up of two main types of light-sensitive receptor cells, called rods and cones, and neural cells connected to them

Photopigments

light-sensitive chemicals that absorb the energy and wavelength from light which causes molecules to break down in the pigments and starts a chemical reaction that either activates or inhibits a neuron

rods and cones

Two kinds of photoreceptors. connect to bipolar cells which connect to ganglion cells and then optic nerves

rods vs cones

rods help differentiate light and dark shades, cones differentiate between different shapes and colors

what are the three types of cones?

red, green, and blue sensitive types

color blindness causes

direct issue with cones that help determine what color something it

how many cones may people have?

4\.2-96 million

Rhodopsin

photopigment in the rods of the eye

Iodopsin

photopigment in the cones of the eye

Fovea:

A 1.5-mm-diameter circle in the middle of retina that contains the greatest concentration of cones

Do we have more rods or cones?

cones

Visual acuity

ability to distinguish details.

Receptive field

area of the retina from which a ganglion cell receives its input. Optic nerves sends info to brain.

Why is there higher visual acuity on the fovea?

Cones don’t share many ganglion cells so there is a better ratio of neurons to cones

When are light receptors more active?

when they are not being stimulated by light

photoreceptors

covert light energy into nerve impulses that the brain can understand

horizontal cells.

modify the rate of electrical firing. connect to photoreceptors and bipolar cells. The reduction of glutamate can modulate activity in other (exciting or inhibiting it) info is transmitted through horizontal cells so rods and cones can interact with each other.

Amacrine cells

similar to horizontal cells. Modulate between two bipolar cells and directly to ganglion cells. at the end of the process.

optic nerves

Axons of ganglion cells joined together. left controls right and vv. Runs down at the optic chiasm and splits. carries info to the brain.

blind spot

Where nerves exit the eye and there are no receptors

Visual field

part of the environment being registered on the retina

Retinal disparity

discrepancy in location of an object’s image on the two retinas

how come wavelength does not always predict color?

Color is merely observer’s experience of a wavelength. It is a perception.

Trichomatic theory

asserts that just three color processes account for all the colors we are able to distinguish.

Opponent process theory

attempts to explain color vision in terms of opposing neural processes

Complementary colors

colors that cancel each other out to produce a neutral gray or white

Color blindness (color vision deficiency)

individual has a poor or absent response from one or more cone types, leading to difficulty distinguishing certain colors

Retinotopic map:

layout of visual cortex, where adjacent retinal receptors activate adjacent cells in visual cortex

Form vision

detection of an object’s boundaries and features

Lateral inhibition

retinal boundary where each neuron’s activity inhibits the activity of its neighbors and in turn they inhibit its activity

Simple cells

cells that respond to line or edge at specific orientation and place on retina

Complex cells

cells that continue to respond when a line or edge moves to a different nearby location

Spatial frequency theory

visual cortical cells do a Fourier frequency analysis of luminosity variations in a scene

Three types of color receptors

red sensitive, green sensitive, and blue sensitive

color blindness

individual has a poor or absent response from one or more cone types, leading to difficulty distinguishing certain colors

Retinotopic map

layout of visual cortex, where adjacent retinal receptors activate adjacent cells in visual cortex