Biosciences in the 21st century Lecture 2: Innovations and Challenges Dr. Michael Burger 1 Outline: Review of last time Organization of the nervous system (in brief) The mapping concept Bionic implants and our cyborg future Auditory function and cochlear implants Restoring paralysis: promising technology 2 3 4 Nervous system is segmented in invertebrates Each segment is controlled by its own bit of brain 5 and in vertebrates........ Human stage 11 embryo Each segment has repeatable structures http://embryology.med.unsw.edu.au/wwwhuman/Stages/Stage10L.htm 6 Each segment has its own inputs and outputs Afferents (inputs; i.e. sensory neurons) Efferents (outputs; i.e. motor neurons) 7 Let s consider the somatosensory system.... 8 each vertebral segment is connected to a particular patch of skin The area of skin innervated by one segment is called a dermatome You will see that this organization is preserved at every level of processing 9 The brain (also segmented) has its own afferent and efferent nerves 10 The neocortex is an elaboration of the foremost segment, and it has a highly organized structure 11 The cortex has functionally distinct regions a closer look at the somatosensory cortex... http://www.emc.maricopa.edu/faculty/farabee/BIOBK/cerebrum_1.gif 12 The somatosensory and motor cortex contain orderly maps of the body surface somatosensory Motor The representation is distorted because more brain tissue is devoted to the most sensitive areas 13 This distorted representation gave rise to the concept of the homunculus or little man in the brain The point is: the brain is organized into maps of important features and functions 14 The point is: the brain contains maps of features and functions The more that we understand about the structure and function of each region of the nervous system, the more likely we are to be able to develop an intervention when things go wrong..... 15 Neurological Medicine: Today: mainly concerned with limiting damage as it happens, or slowing degenerative processes. Sometimes medication can correct de ciencies in neurotransmitter systems etc. Long term: stem cells, tissue engineering, gene therapies will correct the mechanisms of disease, not just the symptoms The intermediate term: current research in nanoscale engineering, computer science, and neuroscience will lead to technological interventions that provide solutions to neurological disease 16 The dawn of the brain machine interface... welcome to your cyborg future.... 17 The most successful machine/neuron interface thus far is the cochlear implant 18 Sound is de ned by frequency 19 Outer ear Middle ear inner ear (neural) The cochlea 20 21 Organ of Corti -hair cells -support cells -basilar membrane -Primary Auditory Afferents!! 22 Organ of Corti -hair cells -support cells -basilar membrane -Primary Auditory Afferents!! 23 The inner ear translates stimulus frequency to a topographic place This tonotopic organization is the primary mapping feature in the auditory brain 24 The most common cause of hearing loss is hair cell damage and death; in mammals they do not regenerate normal inner hair cells damaged outer hair cells 25 The cochlear implant is an electrode array positioned to stimulate the auditory afferents directly, in the abscence of hair cell function 26 Cochlear Implant Two elements External Internal A microphone A speech processor A transmitter and receiver/stimulator An electrode array Bypasses damaged part of the ear Directly stimulates auditory nerve 27 Age Matters Vocabulary Normal ears &lt; 2.5 years 2.5-3.5 yrs 3.6-7 yrs 7.1-10 yrs The point here: deaf children can recover near normal language ability if (Connor et al. 2006) they are implanted early enough 28 The limit of implantation, is frequency resolution because todays best electrode has a max of 23 inputs to the ear Normal Hearing 29 The limit of implantation, is frequency resolution 6 channel hearing 30 The limit of implantation, is frequency resolution 4 channel hearing 31 Cochlear implants compress sound into bandpass lter channels, but only a few are needed to make sense of the world.... Frequency 32 16 8 4 2 1 Time Frequency 32 Cochlear implants compress sound into bandpass lter channels, but only a few are needed to make sense of the world.... Frequency 32 16 8 4 2 1 # of band lters Time Frequency 33 Cochlear implants compress sound into bandpass lter channels, but only a few are needed to make sense of the world.... Time Frequency 1 2 4 8 16 32 34 <a href="/keyword/music-appreciation/" >music appreciation</a> requires many more channels 35 <a href="/keyword/music-appreciation/" >music appreciation</a> requires many more channels Frequency Johnny Cash 4 8 16 32 Time These audio demos available at... http://www.hei.org/research/aip/audiodemos.htm 36 New technology is allowing researchers and their patients to control machines with only the power of thought, and the help of computers 37 The cortex has functionally distinct regions a closer look at the Motor cortex... 1.Motor neurons re predictable patterns before movement http://www.emc.maricopa.edu/faculty/farabee/BIOBK/cerebrum_1.gif 38 The cortex has functionally distinct regions 2. computer programmers are getting sophisticated enough to have algorithms that interpret the output of 100 s of neurons http://www.emc.maricopa.edu/faculty/farabee/BIOBK/cerebrum_1.gif 39 The cortex has functionally distinct regions 3. computers can then send complex commands to robots http://www.emc.maricopa.edu/faculty/farabee/BIOBK/cerebrum_1.gif 40 New tiny electrode arrays can sample the activity of many neurons at once, and cause minimal tissue damage 41 In 1999, researchers succeeded in demonstrating that a rat could control a single arm robot with signals from motor cortex neurons Chapin ...