* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Motor system basics
Eyeblink conditioning wikipedia , lookup
Time perception wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Brain–computer interface wikipedia , lookup
Neuroscience in space wikipedia , lookup
Nervous system network models wikipedia , lookup
Mirror neuron wikipedia , lookup
Development of the nervous system wikipedia , lookup
Neuroplasticity wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Synaptic gating wikipedia , lookup
Metastability in the brain wikipedia , lookup
Microneurography wikipedia , lookup
Environmental enrichment wikipedia , lookup
Neurocomputational speech processing wikipedia , lookup
Optogenetics wikipedia , lookup
Anatomy of the cerebellum wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Evoked potential wikipedia , lookup
Neuroanatomy of memory wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Central pattern generator wikipedia , lookup
Cognitive neuroscience of music wikipedia , lookup
Embodied language processing wikipedia , lookup
Motor system basics Motor Development Motor neurons & Muscle fibers Local motor control Muscle spindles enforce the “stretch reflex”: feedback about muscle length. Golgi tendon provide feedback about level of force. Spinal chord Central pattern generators Taking care of the basic simple functions... Central pattern generators Central pattern generators De-cerebrate walking cat Postural control Vestibular and Reticular nuclei (medial motor system). Adaptation and Anticipation – Sailor “sea legs” Voluntary control Cortico-spinal and Rubro-spinal pathways (lateral motor system). Fine motor control. ~ 1 Million fibers originating in: • Primary motor cortex (one third) • Premotor cortex (one third) • Somatosensory cortex (one third) Somatotopic organization of M1 Motor system hierarchy Motor system hierarchy Performing actions is complicated… Incorporate: Visual information Auditory information Somatosensory information Make a decision Make a motor plan (timing, forces, balance, etc…) Execute Encoding of M1 neurons: Force Encoding of M1 neurons: Direction Textbook stories describe M1 neurons as responsible for the final motor execution step… Higher motor levels Visual – movement performed according to cue. Internal – movement performed as part of a memorized sequence. Anterior parietal & Premotor cortex Visuomotor coordination Object manipulation Grasping Areas F5 and AIP/PF Canonical neurons – object specific actions Regardless of where objects are located Murata (1997, 2000) Microstimulations Story is a bit more complex. Long microstimulations in premotor, anterior parietal, and primary motor cortex generate complicated multi-effector movements. Like grasp to eat… Idea of motor primitives Supplementary motor cortex Neurons that respond to a specific movement only when it is part of a sequence (a) or to any movement, but only according to its location in the sequence (b). Functional specialization Damage in M1 creates weakness in the relevant part of the body. Damage in parietal and premotor cortex creates problems with movement planning and coordination. Damage in SMA creates problems with learning new movement sequences Motor control So far we have talked about physiology. What is the purpose of the motor system? Encoding space Head centered? Hand centered? Eye centered? Inverse model You need to translate external space to internal space… Inverse model Eventhough you use different joints and muscles for different movements: Movements remain straight, smooth, with symmetric velocity profile. Your motor system cares about making smooth efficient movements in external space… (Morasso 1981) Motor primitives Invariance to scale… Motor primitives Raibert 1977 Invariance to effector… Similar brain solution to very different movements Inverse model is flexible… (Brashers-Krug, Shadmehr, and Bizzi 1996) Inverse model is flexible… Motor memory Where does motor learning happen? How do we study neurophysiology? Dendrites Cell body Axon Neural activity In vitro electrophysiology Control > ASD In vivo electrophysiology Control > ASD In vivo electrophysiology Control > ASD Anesthetized or awake Electrode location Control > ASD Magnetic resonance imaging (MRI) Anatomy - Separating tissues T1 T2 Anatomy – Cortical thickness Anatomy – Cortical folding Anatomy – white matter Tractography Fiber volume Fiber length Brain function Neurovascular coupling Vasculature Changes in oxygenated blood זמן Heeger et. al. 2002 fMRI experiment Experimental results In fMRI we always compare measures over time Converging evidence Good science is achieved by generating hypotheses that can be tested with different types of experiments in order to generate converging evidence.