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AP Psychology SENSATION Chapter 4 (Bernstein), pages 106-149 Introducing Your Senses You have been told you have to give up one of your senses. 1. which one would you choose NOT to have? 2. Why would you choose this sense and not one of the others? 3. Describe the physiological processes/physical structures that would be affected by your lack of this sense. Introducing Your Senses 1. VISUAL DOMINANCE: we are very reliant on our sense of vision and “give priority” to information that comes through that sense. (e.g., the McGurk Effect, The Rubber Hand Illusion) 2. INTERACTION OF TASTE AND SMELL: by giving up smell, you are also giving up much of the flavor of food. In addition, you will no longer be able to use smell to detect danger (e.g., smelling smoke). 3. INCREASED SENSITIVITY: if you lose one sense, the other senses do NOT become more sensitive (e.g., you cannot develop more rods and cones). Rather you do attend more to the other sensory cues and would notice things that you might not otherwise. Introducing Your Senses Physiological Processes/ Physical Structures 1. VISION--lack of rods or cones or damage to the cornea, lens, retina, the optic nerve, the occipital lobe or thalamus 2. HEARING--damage to the tympanic membrane, the mealleus, incus, or stapes (conduction deafness), the basilar membrane, the auditory nerve (nerve deafness), or the temporal lobe or thalamus 3. SMELL--damage to olfactory neurons or the olfactory bulb 4. TASTE--damage to the taste buds or papillae and the thalamus Introducing Your Senses Physiological Processes/ Physical Structures 5. TOUCH--difficulty surviving; wouldn’t be able to swallow or feel pain (which is important!). There could be damage to the skin’s sensory neurons, the spinal cord, and the thalamus 6. KINESTHESIA--damage to receptors in the muscles and joints that send information to the spinal cord and the thalamus 7. VESTIBULAR--no sense of balance or the positions of one’s head in space; could have damage to the vestibular sacs in the inner ear or cerebellum; if problem exists with the vestibular-ocular reflexes produced by the eye muscles, there could be damage to the vestibular sense WHAT ARE OUR SENSES? 1. A SENSE is as system that translates information from outside the nervous system into neural activity. 2. Messages from the senses...SENSATIONS 3. Sensation v. Perception (the process of giving meaning to sensation, Ch. 5) • difficult to distinguish because interpretation of sensations begins in sense organs and continues into the brain WHAT ARE OUR SENSES? 4. Some General Info • stream of info from different senses can interact (e.g., ______________ ) • experience can change the sensations we receive (e.g., ______________ ) • “reality” differs from person to person (e.g., ______________ ) 5. Our senses gather information about the world by detecting various forms of ENERGY (e.g., light, heat, sound, physical pressure). 6. Humans depend primarily on VISION, HEARING, and the SKIN SENSES. SENSORY SYSTEMS 1. The “Steps” in Sensation ACCESSORY STRUCTURES modify/change environmental energy before “detected” by the sensory system itself (ex. the outer ear is an accessory structure that collects sound). 2. TRANSDUCTION converts environmental energy into neural activity (much like translating English into another language). • SENSORY RECEPTORS specialized cells that detect energy forms • Sensory receptors respond best to changes in environmental energy • ADAPTATION is a process in which responsiveness to an unchanging stimulus decreases over time. 3. Sensory nerves carry output from receptors to CNS (spinal cord and brain) 4. for all senses except smell, info goes first to thalamus which relays it to appropriate sensory area of the cerebral cortex for complex processing SENSORY SYSTEMS • The Problem of Coding CODING is the translation of a stimulus’ physical properties into a pattern of neural activity that specifically identifies those properties • DOCTRINE OF SPECIFIC NERVE ENERGIES states that stimulation of a particular sensory nerve provides codes for that one sense, no matter how the stimulation takes place (ex. gently pressing eyeball produces optic nerve activity and little spots of light) • In other words... We have sensory systems which allow us to take in information from the outside world and make “sense” of it in our inside world (the brain). HEARING SOUND is a repetitive fluctuation in the pressure of a medium, such as air. Vibrations of an object produce the fluctuations in pressure that create sound. A wave is a repetitive variation in pressure that spreads out in three dimensions. 3-D sound wave HEARING Physical Characteristics of Sound Sound is represented graphically by waveforms (2-D) which have three characteristics: • AMPLITUDE or intensity is the difference in air pressure from baseline to peak • WAVELENGTH is the distance from one peak to the next • FREQUENCY is the number of complete waveforms, or cycles that pass by a given point in space every second. One cycle per second is 1 hertz (Hz). • Frequency and wavelength are related; the longer the wavelength, the lower the frequency (and vice versa) • Most sounds are mixtures of many frequencies and amplitudes, but a pure tone consists of only one frequency and is represented by a sine wave Fun Science: SOUND AMPLITUDE or intensity is the difference in air pressure from baseline to peak WAVELENGTH is the distance from one peak to the next FREQUENCY is the number of complete waveforms, or cycles that pass by a given point in space every second. One cycle per second is 1 hertz (Hz). Frequency Response Tests HEARING Psychological Dimensions of Sound Physical characteristics of sound waves produce the psychological dimensions of sound. • LOUDNESS determined by amplitude of the sound wave; waves with greater amplitude produce sensations of louder sounds. • • Loudness is described in units called decibels, dB. Zero dB is the minmal detectable sound for normal hearing. PITCH is how “low” or “high” a tone sounds. High frequency waves are senses as high-pitched sounds. • • Humans can hear sounds from about 20 Hz to 20,000 Hz. TIMBRE is sound’s quality. Consists of complex wave patterns that enables you to differentiate sounds. IN REVIEW... Which physical characteristic determines PITCH? Which determines LOUDNESS? What creates the TIMBRE of a sound? PARTS OF THE EAR Outer Ear... CHANNELS sound (pinna, auditory canal, tympanic membrane/eardrum) Middle Ear... AMPLIFIES sound (hammer/ malleus, anvil/incus, stirrup/ stapes) Inner Ear... TRANSDUCES sound (cochlea, basilar membrane, hair cells/ cilia, auditory nerve) An Introduction to Your Ear Part 1 An Introduction to Your Ear Part 2 PARTS OF THE EAR Outer Ear... CHANNELS sound (pinna, auditory canal, tympanic membrane/eardrum) PARTS OF THE EAR Middle Ear... AMPLIFIES sound (hammer/malleus, anvil/incus, stirrup/stapes) PARTS OF THE EAR Inner Ear... TRANSDUCES sound (cochlea, basilar membrane, hair cells/ cilia, auditory nerve) Auditory Transduction (6:44) HEARING Focusing the Sound: THE HUMAN EAR YOUR TASK Create an entertaining and informative SKIT in which your group... ...describes the roles of the cochlea, basilar membrane, hair cells, and auditory nerve in the process of AUDITORY TRANSDUCTION. Include a description of the types of deafness. (GROUPS 1a and 1b see pp. 113-115) ...describes how information is relayed to the primary auditory cortex and how the cortex codes the frequency and location of sounds. (GROUPS 2a and 2b see pp. 115-116) ...describes the process of coding auditory information. Discuss the relationship between PLACE THEORY and FREQUENCY-MATCHING THEORY (VOLLEY THEORY) on frequency coding. (GROUPS 3a and 3b see pp. 116-118) PLACE THEORY v. FREQUENCY-MATCHING THEORY Place Theory Frequency-Matching Theory http://clas.mq.edu.au/perception/psychoacoustics/hearing_theory.html TEST YOUR MAD SKILLS! VISION LIGHT • a form of energy known as electromagnetic radiation • most invisible to the human eye VISION VISIBLE LIGHT • electromagnetic radiation with a wavelength from approx. 400 nanometers (one-billionth of a meter) to about 750 nanometers • does not need a medium to pass through (such as air or water...or molasses) • has properties of both waves and particles (light rays and light waves both correct terminology) • sensations of light dependent upon two physical dimensions: • LIGHT INTENSITY how much energy the light contains; determines brightness • LIGHT WAVELENGTH determines color you sense; different wavelengths produce sensations of different colors (ROYGBIV) VISION Focusing the Light: THE HUMAN EYE Bill Nye on the Eye Anatomy and Function of the Eye VISION How Vision Works Converting Light into Images (VISUAL TRANSDUCTION) PHOTORECEPTORS the specialized cells in the retina that convert light into neural activity PHOTOPIGMENTS chemicals in photoreceptors that respond to light • light strikes photoreceptors • photoreceptors break apart and chemical reaction begins • cell’s membrane polarity changes and signal sent to the brain • in dim conditions photoreceptors make extra photopigment to detect little light • DARK ADAPTATION the increasing ability to see in the dark over time (after half hour, sensitivity increases 10,000 fold) VISION RODS & CONES RODS and CONES the two types of photoreceptors in the retina that differ in shape, composition, and response to light • Approx. 120 million rods and 6-7 million cones • Cones provide the basis for color vision • Cones use one of three varieties of iodosin photopigments, each sensitive to different light wavelengths • Rods use the photopigment rhodopsin, making them more sensitive to light than cones; rods cannot discriminate color • Most cones concentrated in fovea allowing detailed vision, or ACUITY • Variations in density of cones in the fovea account for differences in visual acuity • Rods are located in the periphery of the retina, not in the fovea • Rods are useful for dark vision VISION RODS & CONES INTERACTIONS IN THE RETINA • Rods and cones connect to bipolar cells and then to ganglion cells. • Axons of the the ganglion cells form the optic nerve which extends out of the eye and into the brain. • When amounts of light reaching any two photoreceptors differ, the photoreceptor receiving more light inhibits the output to the brain from the photoreceptor receiving less light, making it seem like there is less light at that cell than there is. VISION RODS & CONES INTERACTIONS IN THE RETINA • LATERAL INHIBITION is made possible by interneurons which make sideways connections between photoreceptors and exaggerate the amount of light reaching them. This exaggeration allows clearer vision. • Each ganglion cell can relay info to the brain only about its own RECEPTIVE FIELD, the part of the retina and the corresponding part of the visual world to which that cell responds • These receptive fields create complex combinations that give us optimum detection of light variations such as edges and small spots of light or dark. • By enhancing the sensation of important features, the retina gives us an “improved” version of the visual world. VISION RODS & CONES INTERACTIONS IN THE RETINA • The OPTIC DISK is located where the optic nerve leaves the eye. • It contains no rods or cones and creates a BLIND SPOT or void in the visual field. • This is unnoticed because the other eye compensates for it. Find your Blind Spot VISION VISUAL PATHWAYS & REPRESENTATIONS • Once the optic nerve leaves each eyeball, the bundle of fibers meet at the OPTIC CHIASM in the brain. Here they cross to the opposite side of the brain. The fibers from the inside half of each eye cross over. The outside half of each eye do not. • This brings all visual info from the left half of the visual world to the right hemisphere of the brain and all visual info from the right half of the visual world to the left hemisphere of the brain. VISION VISUAL PATHWAYS & REPRESENTATIONS • From the optic chiasm, info is sent to the region of the thalamus called the LATERAL GENICULATE NUCLEUS (LGN) where neurons then relay the visual input to the PRIMARY VISUAL CORTEX for complex processing. • FEATURE DETECTORS specialized neurons in the LGN that respond to different aspects of an image such as size, shape, and angle • PARALLEL PROCESSING refers to how the brain processes multiple sources of info at once. It’s still debated as to where all this processing takes place and may involve several regions of the brain, not just the visual cortex. “The Island of the Colorblind” from the BBC series THE MIND TRAVELER with Dr. Oliver Sacks Click HERE to begin program. VISION SEEING COLOR PERCEPTION OF COLOR • How we perceive color depends on three characteristics of light waves: SATURATION, and BRIGHTNESS. HUE, • HUE refers to the color people psychologically experience. It is determined by wavelength. Short wavelengths produce bluish colors. Long wavelength produce reddish colors. Medium wavelengths produce orange, green, yellow colors. • SATURATION refers to color purity. Purity depends on the complexity of light wave. (ex. red comprised of a single wave; pink comprised of a combination of red and white light) • BRIGHTNESS (or VALUE) refers to the intensity of the light wave as determined by the amplitude, or height, of a wave (tall wave/great amplitude would be a very bright color; low wave/low amplitude would be a dull color) VISION SEEING COLOR COLOR MIXING Colors are based on the dominant wavelength present. How colors are mixed determines which color people perceive. (Watch the first 2 minutes of THIS for more!) SUBTRACTIVE COLOR MIXING • occurs by mixing different paint “colors” (pigments) • like other physical objects, paints reflect certain wavelengths and absorb all others • combining all paint colors will result in black ADDITIVE COLOR MIXING • the effects of the wavelengths from each light are added together • mixing two lights of equal intensity results in a color midpoint on a line between the two starting colors on a color wheel • combining all colored lights will result in white One more time! VISION • the eye has three types of receptors, each TRICHROMATIC THEORY OF COLOR VISION (Young-Helmholz Theory) sensitive to a specific wavelength • blue-sensitive cone short wavelengths • green-sensitive cone • red-sensitive cone medium wavelengths long wavelengths • colors other than blue, green, and red triggers combination of cones which produces other colors (ex. purple results from triggering blue and red-sensitive cones at the same time) • COLOR BLINDNESS can be explained by the trichromatic theory • people born with cones containing only two of the three color-sensitive pigments can discriminate fewer colors Click HERE for an explanation from Apple! ...and then HERE for another really short explanation of Trichromatic Theory. VISION OPPONENT-PROCESS THEORY OF COLOR VISION (Ewald Hering) • the color-sensitive components of the eye are grouped into three pairs: red-green, blueyellow, and black-white • each element signals one color or the other but never both • this theory explains AFTERIMAGES when an image is perceived even though the stimulus has been removed (ex. staring at a yellow dot then looking away and seeing a blue dot...the afterimage) • according to Hering, different colors are produced through combinations of the pairs being activated at the same time (ex. purple results from red and blue elements being “on” while the green and yellow elements are “off”) Click HERE for a brief explanation of Opponent-Process Theory of Color Vision. VISION EXPERIMENTS Neuroscience for Kids: VISION EXPERIMENTS Neuroscience for Kids: COLOR VISION OPPONENT-PROCESSING THEORY Demo Colorblindness Test Links: 1, 2, 3, 4 (information only) PROBLEMS WITH VISION Ocular and Optic Nerve Causes of Visual Impairment Neurological Vision Loss The top circle represents visual impairment. The area above the top of the large circle-line represents ocular and optic nerve conditions (60%-70% of the cases of visual impairment). The area of intersection of the two circles represents CVI (30%-40% of the cases of visual impairment). The largest circle represents the processing of visual information. PROBLEMS WITH VISION Ocular and Optic Nerve Causes (see handout) light not focused properly on retina presbyopia, myopia, hyperopia, astigmatism damage to retina retinal detachment (link), retinal degeneration, diabetic retinopathy, macular degeneration (link 1, link 2, link 3, link 4) blurring of light upon entering the eye corneal disease and injury (link 1, link 2, link 3), cataracts (link) damage to the optic nerve glaucoma (link 1 at 16:30, link 2) PROBLEMS WITH VISION Neurological Vision Loss (Cerebral/Cortical Vision Impairment) as much as 40% of brain estimated to be involved in interpretation and translation of visual images generated by the eyes any disruption along processing pathway results in impaired vision various causes traumatic brain injury (sports, accidents, combat injuries, premature infants) asphyxia/interruption of oxygen supply to the brain development brain defects infections of the central nervous system (such as encephalitis or meningitis) FOR MORE INFORMATION: CVI Overview 1,2,3,4 American Foundation for the Blind CVI in Children PROBLEMS WITH VISION PREVALENCE OF VISION IMPAIRMENT (fact sheet from the World Health Organization) 1 285 million people are visually impaired worldwide: 39 million are blind and 246 have low vision. 2 About 90% of the world's visually impaired live in developing countries. 3 Globally, uncorrected refractive errors are the main cause of visual impairment; cataracts remain the leading cause of blindness in middle- and low-income countries. 4 The number of people visually impaired from infectious diseases has greatly reduced in the last 20 years. 5 80% of all visual impairment can be avoided or cured. more information from WHO VISION SYNESTHESIA • involves more unusual mixing of senses that improve the experience of a sensation • “feeling” color or sounds as touches; “tasting” shapes; sensing colors when hearing certain sounds • possibly from connections between neighboring sensory areas of the brain THE CHEMICAL SENSES: SMELL & TASTE OLFACTION (click HERE before continuing) • Olfaction (or Smell) detects chemicals that are airborne, or volatile • accessory structures include nose, mouth, and upper part of throat • odor molecules reach receptors through nose or through opening in the palate at back of mouth • olfactory receptors on dendrites of specialized neurons in the moist lining of the nose (mucous membrane) • odor molecules bind to receptors causing depolarization of dendrites’ membrane and changes in firing rates of neurons • a single odor molecule can cause a change in the membrane potential of an olfactory neuron but normal odor detection requires about 50 molecules THE CHEMICAL SENSES: SMELL & TASTE OLFACTION • each olfactory neuron lives only about 2 months and are repeatedly replaced • humans have approx. 1,000 different olfactory receptors (1-2% of genes) allowing us to discriminate tens of thousands of different odors • IMPORTANCE TO RESEARCH • understanding how olfactory neurons generate may someday be helpful in treating brain damage • how smells are coded in combinations of receptors may help researches develop “electronic noses” that may have an application in national security and medical diagnosis SMELL THIS! (olfactory review) BACK THE CHEMICAL SENSES: SMELL & TASTE More on OLFACTION • the only sense that bypasses the thalamus • olfactory axons extend directly into the brain to the olfactory bulb and then sent to various brain regions for further processing • olfactory bulb’s connection to the amygdala may account for relationship between smell and emotional experiences (losing the sense of smell sometimes indicates brain diseases that disrupt memory and emotion) • mechanism of olfaction similar across species but sensitivity varies greatly (humans have approx. 9 million olfactory neurons; dogs have about 225 million) • no agreement on basic smells BUT WAIT! THERE’S MORE! THE CHEMICAL SENSES: SMELL & TASTE PHEROMONES • Dogs and many other species have an accessory olfactory system that detects these chemicals that when released by one animal and detected by another can shape the second animal’s behavior and/or physiology • in mammals, pheromones can be nonvolatile chemicals that animals lick and pass into an olfactory organ called the vomeronasal organ • role of pheromones in humans less clear • the human vomeronasal organ is capable of responding to certain hormonal substances and can influence certain hormonal secretions • not everyone has a vomeronasal organ • odorants that cannot be consciously detected have been shown to influence mood and can alter parts of the brain that not directly involved in olfaction • a possible human gene for pheromone receptors has been found • pheromones capable of producing physiological changes in humans related to reproduction but no solid evidence for a human (or even a primate) sexual attractant pheromone • associations between certain odors and emotional experiences that enhance sexual attraction is LEARNED • individual mammals, including humans, have distinct “odor type” determined by immune cells and other inherited physiological factors THE CHEMICAL SENSES: SMELL & TASTE GUSTATION • Gustation (or Taste) is the chemical sense system in the mouth • receptors for taste are in taste buds grouped together as papillae in mouth and throat • humans have about 10,000 taste buds (mostly on tongue, also on roof of mouth and back of throat) • human taste system detects only a few elementary sensations (sweet, sour, bitter, salty) • research has identified two other tastes • umami enhances other tastes and is produced by monosodium glutamate (MSG) and certain other proteins • astringent produced by tannins such as those found in teas THE CHEMICAL SENSES: SMELL & TASTE GUSTATION • different tastes transduced into neural activity in different ways • sweetness and bitterness signaled when chemicals fit into specific receptor sites • sour and salty act through direct effects on the ion channels in membranes of taste cells • salty also enhances taste of food by suppressing bitterness • “supertasters”--about 25% of population has thousands of taste buds whereas “nontasters” have only hundreds THE CHEMICAL SENSES: SMELL & TASTE SMELL, TASTE, and FLAVOR • smell and taste act as two components of one system...FLAVOR • most of what makes food taste good comes from odors detected by the olfactory system • ANOSMIA is inability to distinguish smells and also interrupts ability to determine flavor even when the gustation system is in working order • olfactory and gustatory pathways converge in the ORBITOFRONTAL CORTEX where neurons also respond to the sight and texture of food • responses of neurons in this “flavor cortex” also influenced by hunger and satiety (fullness) THE CHEMICAL SENSES: SMELL & TASTE SMELL, TASTE, and FLAVOR • tastes and odor prompt strong emotional responses • reactions to bitter and sweet flavors appear to be inborn • few other innate flavor preferences as most are LEARNED • taste and flavor perception as well as motivation to consume certain flavors is affected by nutritional needs (ex. desire for salty drink or food after exercise) • flavor also affected by texture and temperature Making Sense of Taste THE SOMATIC SENSES • also known as the body senses or somatosensory systems • located throughout the body rather than in specific, localized organs • include the following: 1.skin senses of touch, temperature, and pain 2.proprioception & kinesthesia--the sense that tells the brain where the parts of the body are with respect to each other 3.vestibular system--tells the brain about the position and movement of the head THE SOMATIC SENSES TOUCH AND TEMPERATURE Stimulus and Receptors for Touch • energy detected by the sense of touch is physical pressure on tissue (usually skin) • skin covers approx. 2 yards of surface and weights more than 20 lbs • hairs on skin bend and deform the skin just beneath them • nerve endings in the skin act as receptors that transduce pressure into neural activity; are in, or just below, the skin • exact process of transduction in the skin is still unknown • humans not just passive responders; touch is an active sense used to get specific information • high density of touch receptors in fingertips • some blind people can read 200 words of Braille per minute THE SOMATIC SENSES TOUCH AND TEMPERATURE Adaptation of Touch Receptors • constant input leads to adaptation resulting in reduced response to constant stimulation • somatosensory system responds best to change in touch • neurons fire rapidly when stimulus first sensed • then most neurons slowly return to baseline while only a few fire giving a sense of a constant stimulation Coding and Representation of Touch Information • sense of touch codes info about two aspects of an object in contact with the skin • INTENSITY of stimulus (weight or heaviness) coded by both the firing rate of and number of neurons stimulated • LOCATION coded by the location of neurons responding to touch; input from left side of body goes to right side of brain, and vice versa THE SOMATIC SENSES TOUCH AND TEMPERATURE Temperature • touch and temperature seem to be separate senses; difference not always clear • some sensory neurons of skin respond to change in temperature but not to simple contact • “warm fibers” increase firing rate when temperature is between 95-115 degrees F • temperatures above 115 cause pain and different fibers • “cold fibers” respond to broad range of cool temperatures stimulate THE SOMATIC SENSES TOUCH AND TEMPERATURE Temperature • many fibers responding to temperature also respond to touch causing sensations of temperature and touch/pressure to interact • warm and cold objects can “feel” up to 250% heavier than bodytemperature objects • touching an object made up of alternating warm and cold spots gives sensation of intense heat • people having frostbite feel burning sensation THE SOMATIC SENSES PAIN AS AN INFORMATION SENSE • pain receptors are free nerve endings that extend from spinal cord to skin and muscles (no dendrites) • when stimulated, these sensory neurons cause the release of various neurotransmitters including substance P, a neurotransmitter that activates a “gate” in the spinal cord that either lets pain impulses travel to the brain or blocks their progress (Gate-Control Theory of Ronald Melzack and Patrick Wall) • input from other skin senses (touch, temperature) may “take over” pathways that pain impulses would have used (ex. rubbing area around a wound; cold/hot pack on a injury) THE SOMATIC SENSES PAIN AS AN INFORMATION SENSE • two types of nerve fibers carry pain signals to spinal cord where they are sent to the thalamus and then relayed to somatosensory cortex, frontal lobe, and limbic system (for emotional elements of pain) • A-delta fibers carry sharp pain and are myelinated to carry inputs quickly • C fibers carry chronic, dull aches and burning sensations • each signals different brain areas • different pain neurons cause release of different neurotransmitters (allowing for the development of a variety of new drugs for pain management) THE SOMATIC SENSES EMOTIONAL ASPECT OF PAIN • all senses can have an emotional component, most of which are learned • pain is more direct • specific pathways carry an emotional component of the painful stimulus to areas of the hindbrain and reticular formation (in the limbic system) as well as other areas via the thalamus • necessary for our survival by allowing us to pull or away or stop doing something that could cause us injury • cognition affects our emotional response to pain • understanding the nature of pain makes it less aversive although just as intense • pain-reducing strategies such as distracting thoughts also affects emotional responses to pain THE SOMATIC SENSES NATURAL ANALGESICS • brain closes “gate” by sending signals back down spinal cord resulting in analgesia, or absence of pain sensation in place of normally painful stimulus • at least three chemicals released during stress play a role in the brain’s ability to block pain signals: serotonin, endorphins, and endocannabinoids THE SOMATIC SENSES NATURAL ANALGESICS • endorphins act as pain killers at many levels • in spinal cord, block synapses of fibers carrying pain signals • also released by adrenal and pituitary glands as pain-relieving hormones • “range of use” includes reducing labor pains during late pregnancy to allowing severely injured athletes and soldiers to continue to perform with no apparent pain • once crisis has passed, release of another neurotransmitter reactivates pain sensitivity counteracting endorphins’ analgesic effects THE SOMATIC SENSES PROPRIOCEPTION & EQUILIBRIOCEPTION The proprioceptive senses and the sense of balance provide information about the position of the body and what each part of the body is doing THE SOMATIC SENSES EQUILIBRIOCEPTION Vestibular Sense • often thought of as “sense of balance” • tells brain about position of head in space and its general movements • two vestibular sacs and three semicircular canals in the inner ear are the organs for this sense • vestibular sacs filled with fluid and contain small crystals called otoliths that rest on hair endings • semicircular canals are fluid-filled and arc-shaped tubes with tiny hairs extending into fluid • as head moves, otoliths shift in sacs and fluid moves in the canals stimulating hair endings THE SOMATIC SENSES EQUILIBRIOCEPTION Vestibular Sense • neurons activated and travel along vestibular nerve with auditory nerve, signaling brain about amount and direction of head movement • vestibular system has neural connections to: cerebellum (coordinate body movements), autonomic nervous system (affect digestion), eye muscles (fix eyes on a point in space if head is moving...vestibular-ocular reflexes) • dizziness occurs when fluids in the vestibular system not level The Vestibular System The Organs of Balance THE SOMATIC SENSES PROPRIOCEPTION Kinesthesia • the sense that tells you where parts of your body are with respect to each other • guide all our movements because the brain, with practice, will automatically make them simple and fluid • primary source of kinesthetic information comes from special receptors (proprioceptors) in joints and muscles • transduced info goes to spinal cord to thalamus to cerebellum and somatosensory cortex for smooth coordination of movements The Proprioceptive System Enhancing proprioceptive quality & adaptation: The following exercises and body systems have an effect on proprioceptive awareness. • Movement for movement's sake in any variety of movement patterns and ranges of motion with different tensions/loads (i.e., dancing, tai chi, yoga). • Traditional cardio, strength and flexibility conditioning. • Balance conditioning, eyes open and closed. • Rotational movements (not just linear and lateral). • Visual acuity: Use vision to adjust movements when recovering balance. Instead of focusing downward, look ahead to realign the head and neck. • Auditory system: The inner ear registers head and body movement like a built-in level. To function properly, the head and neck must be situated over a balanced spine. • Rhythm: Heart beat, breathing patterns and even walking are rhythmic by nature. Have clients strive to feel rhythm during sports and as they work out. • Stance: Movements should be initiated from an "athletic stance" (ankles, knees and hips slightly flexed) and an upright posture. Stance is also referred to as the clients' "base of support," or the distance created between their feet. • Weight transfer: Bodies are especially sensitive to weight changes that take place with stance or postural shifts. Clients will feel weight transfer from the feet upward. • Constant motion: Have clients get a feel for constant, dynamic movements (versus static positions) as they try the drills mentioned in this article. FROM: FITNESS MANAGEMENT MAGAZINE--A PUBLICATION DIRECTED TO FITNESS/HEALTH/ATHLETIC CLUBS AND FACILITIES