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CU-Boulder PSYC 2012 - bio psych lecture 17 notes

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3/17/15 – Lecture 17 – Motor Behavior: CNS Control of Movement- Goal: to determine how our nervous system produces voluntary movement- Sensorimotor System: the parts of the brain, spinal cord, and peripheral nerves that produce movement and provide feedback about movemento Movement is a major characteristic of animalso Hierarchical Control of Movement Movement starts with a goal, then it is operationalize into a pattern of movements for achieving that goal The pattern of coordinated movements is converted into activation of relevant muscles, sensory information provides feedback about the movement Errors have to be detected and corrected- CEO -> Managers -> Workers -> feedback surveyo Main Structures Involved in Neural Control of Movement Frontal Cortex – initiates and plans movement Brainstem – relays commands to the spinal cord Spinal Cord – transmits signals to lower motor neurons Muscles – carry out movements Basal Ganglia – regulates the force of movements Cerebellum – detects and corrects errors in movement Somatosensory System – provides sensory feedback about movemento The Frontal Cortex and Initiation of Movement Prefrontal cortex: initiates movement goals (PLANS)- Very important with initiating complex behaviors, goals and ideaso It also decides if an action is appropriate – impulse control- Does not specify the precise pattern of movements to be made (the premotor cortex does this)- Neurons in the prefrontal cortex sends their axons to the premotor cortex- Lesion or Damage to Prefrontal Cortex?o Impulsive or inappropriate behaviors Premotor cortex: organizes movement patterns (SEQUENCES)- Produces complex movement patterns or sequences necessary to accomplish the task- Neurons in the premotor cortex send their axon messages to the motor cortex- Lesion or damage to the premotor cortex?o Affect the ability to put together complex movements is interfered with Motor cortex: actually sends out the commands for producing specific movements through different patterns of muscle activation (EXECUTES)- The neurons of the motor cortex are arranged in groups that produce movement of key body parts- Motor Homunculus – a representation of the motor cortex mapo Greater size of hands, lips, and tongue reflect greater motor innervation of these parts due to their finer movement abilities- Motor cortex neurons send their axons down through the brainstem as well as to the basal ganglia and the cerebellum- Lesions and Damage to the Motor Cortex?o Can lead to paralysis or inability to carry out specific movementso The Brainstem Region where axons from motor cortex enter the spinal cord- Main area there axons controlling limbs cross over to the other side of the spinal chord- Important in producing species-specific behaviorso Ex: cats cleaning in a particular way, flipping over and landing ontheir feet, hissing and arching when scaredo Ex: dogs panting, shaking off water from its nose to its tail, usingits hind leg to scratch its bodyo The Spinal Cord Upper motor neurons from motor cortex continue to descend from the brainstem down to the spinal chord upper motor neurons synapse onto lower motor neurons lower motor neurons exit spinal cord via the ventral root- Spinal cord and lower motor neuronso The axons of lower motor neurons exit the spinal cord in ventral root of spinal nerveso Lower motor neurons axons synapse on muscle fibers within themuscleso Skeletal Muscles Consists of long, cylindrical cells called muscle fibers Special proteins inside muscle fibers called contractile proteins pull on one another, causing contraction or shortening of muscle fibers- Contracting of muscles pull on bones and move joints and produce movements- Each muscle fiber gets innervated by a SINGLE motor neurono However a single motor neuron can innervate multiple muscle fibers – motor units Increase amount of motor units or the strength of the motor unit messages Muscle Agonists and Antagonists- Agonist – a muscle that causes specific movement or possibly several movements to occur through the process of its own CONTRACTION- Antagonist – a muscle that acts in opposition to the specific movement generated by the agonist and STRETCHES o Most movements require the coordinated, alternating activationof agonists and antagonists- Feedback and Motor Behavior: the basal ganglia, the cerebellum, and sensorimotor inputo Basal Ganglia – group of nuclei in the forebrain Main structures are caudate and putamen (striatum) Basal ganglia neurons receive input from the frontal cortex and the substantia nigra (regulates voluntary vs involuntary movements) on motor behavior and from the sensory cortex on the success of motor behaviors- Basal ganglia neurons sends axon messages back to the motor cortex through the thalamus and back to the frontal cortexo Can increase or decrease the action potentials/ force included with the movement Damage to Basal Ganglia (regulates the force of movements and suppresses involuntary movements)- Hyperkinetic symptoms and the direct pathway – involuntary and/or excessively forceful movementso Huntington’s chorea and Tourette’s Syndrome tics- Hypokinetic symptoms and the indirect pathway – rigidity and decreased movement productiono Parkinson’s Disease (death of substantia nigra that destroys the direct pathway and over fuels the indirect pathway)o The Cerebellum and Movement Correction The cortex sends movement information down spinal cord muscles- also receives a copy of this motor program from the cortex via the inferior olive- the cerebellum compares the motor program with sensory feedback about the movemento sends corrective feedback to the premotor cortical neurons so that the next time the motor program is sent down it is adjustedbased on this sensory feedback and experienceo WHAT TO DO BETTER NEXT TIME! Implicit memory Damage to the cerebellum?- The Somatosensory Systemo 4 Somatosensory Receptors Nocioception – (skin) pain Thermoreceptor – (skin) temperature Hapsis – (skin) fine touch and pressure Proprioception – (muscles, tendons, and joints) body awareness, muscle stretch,and joint angleo Somatosensory Neurons Unipolar Neurons with one long dendrite that connects directly to the axon- Connect to the spinal cord via spinal nerves- Dorsal Root Ganglion – contains cell bodies of sensory neuronso Somatosensory Cortex Sensory information enters


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