CH. 3 Sensory Systems

PSYC 305 Brain and Behavior

Transduction

The conversion of physical energy (light, sound waves, pressure, etc.) into the activity of neurons

Sensory Info Processing

Energy → sensory receptor cells (transduction) → neural pathway → primary cortical receiving area → higher order cortical processing (association cortex)

Retina

The region in the back where light is received

Photoreceptors (rods and cones)

Light sensitive cells in the retina

Region with NO photoreceptors

Optic disk or blind spot

Sensory receptors for the auditory system

Hair cells

Auditory system process

Sound waves cause eardrum to vibrate → vibrating eardrum causes ossicles to vibrate → ossicles transmit the vibrations to the fluid inside the cochlea

Touch receptors

Mechanoreceptors

Pain receptors

Nociceptors

Touch signals are sent through

Spinal cord neurons, thalamus, primary somatosensory cortex

Olfaction process

Odorants detected in air → olfactory receptors are activated → neurons connect to the olfactory bulb → information travels to the primary olfactory cortex via mitral cells

Where does smell not pass through

Thalamus

Gustation

Taste buds in tongue contain taste receptor cells that detect tastant molecules → taste receptor cells synapse upon cranial nerves which carry taste signals to the medulla → signal is sent to the thalamus and finally to the gustatory cortex

Vision transduction pathway

Stimulus: visible light → receptor type: photoreceptors → key pathway: optic nerve tract to thalamus to visual cortex

Audition transduction pathway

Energy: sound waves → receptor type: hair cells → auditory nerve to cochlear nucleus to auditory cortex

Somatosensation transduction pathway

Stimulus: touch/pressure/painful stimuli to skin → receptor type: mechanoreceptors and nociceptors → key pathway: axons of somatosensory neurons to spinal cord to thalamus to somatosensory cortex

Olfaction transduction pathway

Energy: odorant molecules → receptor type: olfactory receptors → key pathway: axons of olfactory neurons to olfactory bulb to olfactory cortex

Gustation transduction pathway

Stimulus: tastant molecules → receptor type: taste receptors → key pathway: cranial nerve to medulla to thalamus to gustatory cortex

Preferred stimulus of a neuron

Receptive field

Objects in left visual field are perceived on which side

Right side of brain

Light at shorter wavelengths is percieved as

Blue/ cooler colors

Light at longer wavelengths is perceived as

Red/ warmer colors

Light at higher amplitudes is perceived as

Brighter

Light at lower amplitudes is perceived as

dimmer

The dorsal stream is known as the ___ pathway, while the ventral stream is known as the ____ pathway

where; what

Cones

Clustered in center (fovea), high degree of visual acuity, detect colors

Synesthesia

Combining of senses (sounds produce colors)

Chemicals in the food dissolve in saliva, moving through a central pore in the taste bud, and binds to ____

Taste receptors

Conductive hearing loss

Sound waves are prevented from reaching the eardrum, or vibrations of the eardrum to the ossicles

Sensorineuronal hearing loss

Dysfunction of the cochlea and hair cells or the auditory nerve

Central hearing loss

Disruption between the auditory nerve and higher-level brain regions

Four major skin receptors for touch

Merkel’s disks, meissner’s corpuscles, ruffini endings, pacinian corpuscles, nociceptors

Merkel’s disks

Respond to light touch

Meissner’s corpuscles

Respond to touch and slow vibrations

Ruffini endings

Respond to stretching of the skin (pressure) and warmth

Pacinian corpuscles

Respond to brief, deep pressure and rapid vibrations

Pupil

Opening for light in the eye

Cornea and lens

Structures that focus the light

Rods

In the periphery of the retina, more sensitive to light, helpful in low illumination

Information flows from the ____ to ____ to _____

photoreceptors; bipolar cells; retinal ganglion cells

Optic chiasm

Where optic nerves from both eyes cross