4.19.11 wk 3 lect. 6Tuesday 5pm review sessionSleep theoriesSleep protects: sleeping in the darkness when predators loom kept our ancestors out of harms waySleep recuperates: sleep helps restore and repair brain tissueSleep helps remembering: sleep restores and rebuilds our fading memoriesSleep and growth: during sleep pituitary gland releases growth hormone. Older people release less of this hormone and sleep less.Functions of sleep/ evolutionary modelThe species that are hunted the most(cows) sleep less/ predatory animals(cats) sleep more neuralogy of sleep is based upon the study of catsRecuperative processrestoring functions in the brain/ during slow wave sleep there is associated with decrease in brain metabolic rate/ if you have a very active day there is an increase in slow-wave sleep/ slow wave sleep increase if you had a lot of brain mental action/ slow wave sleep appears to participate in hippocampal-dependent memory consolidationSleep abnormalitiesInsomnia-related to stress, drugs, pain, other disturbancesSleep apnea-breathing problem/ common in people that are overweight/ throughout the night they’re constantly waking up and feel exhaustedNarcolepsy- sudden sleep attacks that are uncontrollable and dangerous/ associated with eating behaviorREM without atonia -REM sleep accompanied by motor activity that appears to accompany dreamingCataplexy- loss of muscle reflexes. Muscular paralysis that occursSensation and PerceptionSensation: the process by which our sensory receptors and nervous stystem receive and represent stimulus energies from our environmentPerception: the process in which our brain begins to organize info and make interpretation/ recognize familiar objects5 senses: vision, audition, taste smell(chemical senses), skin senses( touch, pressure, temp., pain), vestibular(head and body orientation) etc../ there are special receptors that respond to these sensesgenerate neural signals to the brainReception, transduction, codingStimulus (physical event), receptors (assembled in organs, diffuse, selective, sensitive to particular range), brain(coding, decoding, perception)Transduction- conversion of physical or chemical stimulus into electrochemical messages for transmission as nerve impulses to the brain/ stimulus into neural impulses/ once you get neuron firing then it depends on where it’s going/ the receptors are specialized because they send signals to special areas in the brain/ the brain can get cross wiredMethods of info. ProcessingBottom-up: coming in through the sensory receptors and working their way up to the brain/ individual elements of a stimulus are integrated to form a whole(create meaningful experience)/ pick up info. From receptorsEx: in the case of a camp fire the light and smell stimuli is sent to the brain through receptors and we have memory and expectations it gets organized into what we’re experiencing Ex: Listening to the sound breakdown to words and breakdown to bigger sentencesTop-down: info. Guided by higher-level mental processes/ drawn by expectations and experiencesMaking of speak and talking: begin with what your going to say and break that idea into sentences and the sentences is broken down into sound to transmit the thoughtPsychophysics: physical energy or other sensory properties is processed into a psychological experience/ make our perceptions based on stimuli We have a physical world with stimuli (ex: light and brightness/ sound (physical world) and volume (psychological world/perception)Intensity of the stimuliabsolute threshold- the minimum stimulation needed to be detected 50% of the timeEx: candle flame seen at 30mi. away at night/ the tick of a watch at a distance of 20ft/ the drop of perfume diffusing through a 3 bedroom apt.--> levels of approximate thresholdDifference threshold: We perceive differences in the same stimuli by constant minimum percentageEx: adding 10g to 100g is 10% change and you will notice a change/ the percentage change provide the bases for the threshold/ when can you detect at difference at 50% ofthe timeSignal detection: identifying the presence of some stimulus when there is an array of bckgrnd noise and info. / no singal threshold but is based on motivation and level of alertness/ distinguished by false alarms ratio of hits to false alarms(ex: detecting blips on a radar screenCertain stimuli can occur slightly below the threshold of 50% and you can still notice the changeSensory adaptation: sensory mechanisms have evolved to detect change in the nature and intensity stimuli/ diminished sensitivity as a consequence of constant stimulation(ex: won’t sense a band aid after a while of it being on your arm)Selective attention: focus our awareness on particular stimulus/ perceptions about objects change from moment to moment (different forms of a cube)VISIONWavelength(frequency)=color the frequency gives us some detection of the colorThe amplitude gives us intensity or brightness of the lightShort wavelengths to long wavelengths have to impact receptors which transduce info. Into neural impulseLight comes in passes through pupil into retina where receptors (rods and cons) provide info. Into another cell which integrates info. From other cells and then another integration from another cellOptic nerve exits towards a lateral part of the eyeball and then goes to the brain No photo receptors at the blind spot The image is inverted in reverse in the lens (upside down) and the brain re-inverts it so we see our world right side upThe image is not being directed correctly on to the retina layer it is projected to far back etc.. in near sighted peopleMore rods than cons(in the region of the eye called the fovea). Cons are centered in image is more pure and sharper not very sensitive in dimlights / color sensitive see objects but not color in the darkness detail and sensitiveFunction in the dark with rods less localized in center are more in the periphery look at something in the dark at an angle because rods are in the peripheryLight is diffused through other cells such as bipolar cells and ganglion cells before it hits the rods and cons The axons of the ganglion cells form the axons that go to the brainMost of the cons have a direct connection to the brainThe cons become dysfunctional or degenerate good peripheral vision but bad acute vision (trouble reading)The fovea has the best vision because you don’t have to go through the layers of the other cells