PSYC 1315 1st Edition Lecture 9 Outline of Last Lecture I Basic Principles II Visual System Outline of Current Lecture I Properties of sound II Structure of the ear III Auditory processing IV Other senses V Pain Current Lecture I Properties of Sound II Wavelength distance between peaks i Determines frequency ii Perceived as pitch iii Some wavelengths cannot be perceived Amplitude height of wave i Perceived as loudness Mixture of Wavelengths Complex Sounds i Perceived as timbre tone saturation Structure of the Ear The outer ear consists of the pinna and the external auditory canal The middle ear consists of the eardrum hammer anvil and stirrup The inner ear consists of the oval window cochlea and basilar membrane These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III Auditory Processing Pathway of Auditory Information i cochlea auditory nerve brain stem temporal lobe ii most sensory information crosses to contralateral hemisphere Localizing Sound i intensity 1 distance 2 sound shadow ii timing IV Other Senses Chemical i Smell utilizes chemoreceptors directly connected to the olfactory epithelium of the upper nasal passage Airborne molecules travel to your olfactory bulb and then project onward to the primary smell cortex located in the temporal lobe ii Taste utilizes chemoreceptors located on the tongue called papillae which contain taste buds Taste is first transmitted to the thalamus before being relayed onto higher areas of the forebrain associated with taste Kinesthetic and Vestibular i Kinesthetic 1 movement posture orientation 2 muscle fibers and joints 3 proprioceptive feedback 4 us moving in our environment ii Vestibular 1 balance and acceleration 2 semicircular canals Skin Cutaneous i Touch 1 Receptors spinal cord thalamus 2 Somatosensory cortex of the parietal lobe ii Temperature 1 Thermoreceptors warm and cold a Help maintain body temp b Subset of mechanoreceptor 2 Simultaneous warm and cold perceived as hot Phantom Limb i Sensory information is confused ii When someone loses a limb they can still feel pain iii Mirror therapy to release pain V Pain Dr Henry Knowles Beecher i Beecher compared the responses of soldiers and civilians with similar injuries 1946 1956 ii Soldiers in the battle field during WWII with serious wounds and undergone surgery but they experienced relatively little pain iii 49 reported moderate or severe pain and 32 requested opiate medication iv Ten years later he conducted a similar study with civilian participants undergoing similar surgeries but less extensive wounds and found that they experienced far more pain 75 reported moderate to severe pain and 83 requested medication v Why is more pain reported in civilians with lesser injuries 1 Because soldiers perceive this injury as a good thing because they get to go home Civilians perceive it as really bad Variability of Pain i Perception is key ii These examples illustrate that pain is not simply determined by the extent of tissue damage but by many factors including the expectations and emotional state of the individual the context and the nature of the injury iii Although this variability has long puzzled pain researchers animal and human studies have led to major advances in understanding the neurobiological and psychological mechanisms that can inhibit or promote pain Definition of Pain i Pain is a sensory and emotional experience associated with actual tissue damage or described in terms of such damage ii Pain is a sensory experience associated with activation of nociceptors and pain pathways iii Tissue damage is not necessary 1 Brain can tell you to feel pain even with no tissue damage Why Is Pain Important i Pain is adaptive for our survival ii Alerts us to danger iii Motivates escape and avoidance learning 1 Touching a hot stove when little iv Motivates recuperation Pain Prevalence i Common pain disorders in the US 1 Inflammation or nerve damage 2 Arthritis 3 Neuropathic pain 4 Low back pain 5 Upper back pain 6 Migraine 7 Degenerative diseases MS ii Pain accounts for 80 of all doctor visits over 100 billion in health care costs and a reduction in work productivity and overall well being Types of Pain and Nociception i 3 major types of Pain 1 Mechanical smash finger 2 Thermal burn hand on hot stove 3 Chemical rub eyes after touching hot pepper chemical burn ii All mediated through nociceptors iii Nociception the neural process of encoding and processing noxious stimuli iv Nociceptors sensory neurons that responds to potentially damaging stimuli what transmits pain stimuli 1 All signals pass through a common pathway in the spinal cord and brain Two Major Types of Pain Fibers i A delta fibers 1 Thick myelinated fast conducting neurons 2 Synapse on cells in the spinal cord that lead to an area of the thalamus called the ventrobasal complex also receives neurons that mediate touch 3 Sends its output to the somatosensory cortex which allows us to localize where the pain originates ii C fibers 1 Very thin unmyelinated slow conducting 2 Mediates a slow dull burning pain 3 C fibers synapse on cells in the spinal cord which then relays to a midline nucleus in the thalamus and onto the limbic system which is responsible for the motivational and emotional aspects of pain 4 Those connections are important for the interpretation and perception of pain Pain Transmission Modulation i Research has clarified that the experience of pain is due to the combined activity of two distinct systems that transmit and modulate pain ii Ascending Nociceptive System get cut stimuli goes to brain 1 Bottom up process of pain 2 Which provides the brain with information about tissue damage iii Descending Inhibitory System going from brain to spinal cord 1 Top down process of pain 2 Which regulates pain transmission Pain Transmission Pathway i Primary afferent nociceptors located in all pain sensitive regions of the body respond to intense thermal mechanical and chemical stimuli ii Activated by chemical peptides bradykinin prostaglandins histamine substance P etc released during tissue damage and inflammation causing transmission of action potentials 1 Nociceptors release peptides when come in contact with damaged tissue iii Axons of these neurons carry the signal into the spinal cord and release neurotransmitters that activate pain transmission neurons in the dorsal horn of the spinal cord iv Pain transmission neurons