CHAPTER 4 – SENSATION

* Sensation – message from a sense, which comprises the raw information that affects many kinds of behavior and mental processes

* Sense – a system that translates data from outside the nervous system into neural activity, giving the nervous system, especially the brain, information about the world



SENSORY SYSTEMS

* Must provide information about the body's relationship to the external environment

* Accessory structures - 


* Transduction - convert incoming energy into _______________ or 
   ___________________


* Sensory receptors - specialized cells that respond to ___________________


* Nerves carry signal from receptors to the ________________

* Thalamus receives and relays information to ______________ (except __________ sensations)

* Cortex produces _____________ and ______________


CODING OF STIMULUS INFORMATION

* Coding – conversion of an item’s physical features into specific pattern of _________ activity, which represents those features in the brain 



* Doctrine of specific nerve energies – stimulation of a particular sensory nerve provides information for ___________________


FORMING REPRESENTATIONS OF STIMULI

* Generally, input from the world is represented “contralaterally” 



* Topographical representation – sensory areas of __________ are organized into maps of the external world 



* Extent of representation – related to density of _______________ for a given sense



* Columns of similar functioning neurons in primary cortex 



* Association cortex – forms representations using more than one ______________



VISION

* Type of stimulus = LIGHT

* How do we sense light?  Shine a light on your brain??


Behind the Sensation: Vision Revealed

* Cornea - transparent protective layer

* Pupil - opening behind cornea

* Iris - constricts or relaxes to adjust amount of light that enters

* Lens - bends light rays

* Retina -

* Photoreceptors - specialized cells that convert _____________ into neural activity

* Contain photopigment - chemicals that respond to light


* Rods =


* Cones =


* Bipolar cells

* Receives information from ___________ photoreceptors and sums up the message


* Interneurons -


* Ganglion cells send information to the brain


* Blind spot - 



* Optic chiasm - fibers cross over to different hemispheres in the brain

* Visual information about _______ half of visual field to the _______ hemisphere and _____________

* Information reach the thalamus and is relayed to the visual cortex in the occipital lobe

* Feature detectors - 





AND THE WORLD PAINTED WITH COLORS

* Hue - essential color, determined by dominating wavelength in mixture of light

* Saturation - purity of color, more pure if one wavelength is relatively more intense

* Brightness - overall intensity of all wavelengths making up the light


Theories of Color Vision

* Trichromatic Theory of Color Vision

* Young-Helmholtz discovery



* Inferred that:

* There must be only ________ types of color photoreceptors that were sensitive to different wavelengths

* The information from these photoreceptors were combined to produce sensation of color


* Research has found that there are 3 types of cones

* Short-wavelength (blue)
* Medium-wavelength (green)
* Long-wavelength (yellow)

* Opponent-process theory of color vision


* Inferred that there are 3 pairs of visual elements

* Red-green
* Blue-yellow
* Black-white

* Center-Surround fields of ganglion cells- stimulation of one element in the pair _______ the other


* Afterimages - when one elements of the pair is no longer stimulated, the other is ____________ to compensate

* Synthesis of the Trichromatic and Opponent-process theories

* Trichromatic - correct at the level of ________________


* Opponent-processes - correct at the level of the ________________


* Colorblindness –


HEARING

Coding Intensity and Frequency

* Place Theory - 



* Frequency-Match Theory - 




Deafness

* Conduction deafness – 



* Nerve deafness - 




OLFACTION (SMELL) AND GUSTATION (TASTE)

* The mathematics of sensation:

____________ +  ____________ = _______________

* Closely linked to memories and emotions

SOMATOSENSORY (TOUCH, TEMPERATURE, PAIN)


* Gate control theory – 



* A-delta fibers = 


* C fibers = 



PROPRIOCEPTION

* Vestibular sense -



* Kinesthesia - 



ADDITIONAL LEARNING OBJECTIVES

* Define sound. Describe the physical characteristics of sound, including amplitude, wavelength, and frequency. (see Hearing)
* Describe the psychological characteristics of sound, including loudness, pitch, and timbre. Discuss the relationship among pitch, frequency, and wavelength as well as that between amplitude and loudness. (see Psychological Dimensions of Sound)
* Name and describe the accessory structures of the ear. (see Auditory Accessory Structures)
* Describe the roles of the cochlea, basilar membrane, hair cells, and auditory nerve in the process of auditory transduction.
* Describe how information is relayed to the primary auditory cortex, how the cortex codes the frequency and location of sounds, and why this coding is important for language. (see Auditory Pathways and Representations)
* Define synesthesia. (see The Interaction of Vision and Hearing:  Synesthesia)
* Describe the transduction process in the olfactory system. Discuss the path that olfactory information follows to the brain. Define pheromones and vomeronasal organ. (see Olfaction)
* Define gustation and papillae