Cook Cognitive Motor Slides PDF

Consciousness State of consciousness: level of arousal (awake, asleep, etc.) Measured by behavior and brain activity Conscious experience: thoughts, feelings, desires, ideas, etc. This refers to a capacity to experience one’s existence rather than just recording it or responding to stim...

Consciousness State of consciousness: level of arousal (awake, asleep, etc.) Measured by behavior and brain activity Conscious experience: thoughts, feelings, desires, ideas, etc. This refers to a capacity to experience one’s existence rather than just recording it or responding to stimuli like an automaton. While you have a “mental life”, your laptop probably does not. Quanta Magazine Philip Ball  The electroencephalograph (EEG) Mainly measures activity of neurons located near the scalp in the gray matter of the cortex. (typically 20-100 microvolts) Voltage Frequency is related to levels of responsiveness. Amplitude is related to synchronous neural activity. EEGs reflect mental states Slow frequencies Fast frequencies Stages of sleep Low amplitude High frequencies Low amplitude 30 to 45 minutes High amplitude Low frequencies Low amplitude High frequencies  Physiological changes during sleep REM REM Increased eye movement Increased inhibition of skeletal muscle (low muscle tone, but twitching can Sleep apnea: sudden occur) reduction in respiration Increased heart rate and respiration  States of consciousness Preoptic area of hypothalamus Suprachiasmatic nucleus of the Reticular activating hypothalamus system Circadian rhythm  Regulating states of consciousness Aminergic neurons are active Cholinergic neurons are active Sleep Increased histamine Increased inhibition  Motivation and emotion Motivation: produce goal directed behavior Emotions: accompany our conscious experiences  Mesolimbic dopamine pathway Reward pathway Prefrontal cortex Midbrain Dopamine is the primary neurotransmitter Locus ceruleus in the (Amphetamines) reticular activating system  Self stimulation experiments stimulator Continuous activation of reward related areas of the brain.  Limbic system Emotions Olfactory bulb Hippocampus (memory) Amygdala  Altered states of consciousness Schizophrenia: diverse set of problems in basic cognitive processing. Wide range of symptoms including hallucinations and delusions. Affects one out of 100 people. Reducing the effects of dopamine can improve symptoms. Mood disorders: Depression - decreased activity in the anterior limbic system. Treatments increase the levels of serotonin and norepinepherine in the extracellular space around synapses. Bipolar disorder - swings between mania and depression. Treatments include lithium that reduces certain synaptic signaling pathways. Louis Wain’s cats  William Utermohlen’s self portraits 1967 1996 2000  Learning and memory Conscious experiences that can be put into words Hippocampus Skilled behavior Consolidation: short-term long-term Sleep  Language (usually in the left hemisphere) Broca’s area articulation Wernicke’s area comprehension Aphasia: language deficit  Parietal damage Sensory neglect When things go wrong  Motor behavior Purposeful or goal directed Two types: 1) Voluntary 2) Reflexive  Muscle control: Extension versus flexion Extension Flexion Flexor muscle contracts Flexor Agonist muscle relaxes Extensor Extensor Antagonist muscle muscle relaxes contracts Decrease the angle Antagonist around the joint Agonist Increase the angle around the joint  Reciprocal innervation of muscles 1) Coordinated flexor and extensor muscle activation and relaxation. 2) Limb position is maintained by a balance of flexor and extensor muscle tension.  Motor neurons Only excitatory (ACh) Alpha: innervate skeletal (extrafusal) muscle Gamma: innervate muscle spindle (intrafusal) Cell bodies in ventral horn of spinal cord (spinal nerves) or brain stem (cranial nerves) Receive inputs mostly from interneurons  Spinal afferent (sensory) and efferent (motor) pathways Ascending Descending sensory information motor commands (dorsal columns) Interneuron Dorsal root ganglion Front (ventral) Motor neuron in Sensory afferent ventral horn Ventral root Motor efferent  Spinal interneurons Voluntary movements Proprioceptive feedback Coordinates complex movements ++ + Pain + - - Length monitoring Tension monitoring Spinal interneuron Motor neuron  Spinal reflexes 1) Withdrawal reflex: protects limbs from injury 2) Stretch reflex: controls muscle length a) monosynaptic (primary) b) polysynaptic (secondary) 3) Inverse stretch reflex: controls muscle tension  Reflexes can be modified Most spinal reflexes can be overridden.  Flexion withdrawal Anterolateral reflex Polysynaptic - + Inhibition of motor neurons innervating the ipsilateral extensor Excitation of motor neurons innervating the ipsilateral flexor Ouch! Flexion withdrawal Anterolateral reflex (Cross extensor reflex) - + + + - Excitation of motor neurons innervating the contralateral extensor Inhibition of motor neurons innervating the contralateral flexor Ouch!  Magnitude of withdrawal reflex depends on the magnitude of pain stimulus A > B > C = irradiation Recruitment of interneurons A pment develo nse Feedback loops Respo B Aft in the spinal cord erd Distance of isc har limb withdrawal ge C 1 2 3 4 5 6 Pain Time (seconds) stimulus  Properties of withdrawal reflex 1) Ipsilateral: Flexor muscle contraction Extensor muscle relaxation 2) Contralateral: Flexor muscle relaxation Extensor muscle contraction (cross extensor reflex) 3) Polysynaptic: Interneurons between sensory input and motor output 4) Irradiation: Increase in rate and magnitude of withdrawal response with increased stimulus strength (recruitment). 5) Afterdischarge: Response maintained after stimulus termination (spinal feedback loops).  Spinal reflexes 1) Withdrawal reflex: protects limbs from injury 2) Stretch reflex: controls muscle length a) monosynaptic (primary) b) polysynaptic (secondary) 3) Inverse stretch reflex: controls muscle tension Monosynaptic stretch reflex (knee jerk) Excitation of motor + neurons innervating - the ipsilateral extensor Inhibition of motor Activation of stretch neurons innervating receptor the ipsilateral flexor Stretch extensor muscle Leg kicks  Muscle spindle and Golgi tendon organ Intrafusal muscle fiber Golgi tendon Stretch (activated by gamma organ receptor motor neurons) Muscle length Muscle tension Tendon Muscle spindle Extrafusal muscle fiber (activated by alpha motor neurons) Muscle spindle is in parallel with extrafusal muscle  Muscle spindles Capsule II Ia Afferents (Ia and II) Gamma motor axons Intrafusal muscle fibers  Response of Ia (primary) and II (secondary) afferents Tap Linear stretch (Stretch reflex) Muscle length Ia primary (nuclear bag fibers) II secondary (nuclear chain fibers) Time Ia primary: signal dynamic changes in muscle length (and some static length) II secondary: signal static muscle length  Muscle spindles can lose sensitivity Muscles are lengthen Increase in muscle spindle afferent activity Extension Alpha motor neuron activity Voluntary flexion Muscle spindle collapses Muscles are (sensitivity is reduced) shorten  Gamma motor neurons maintain muscle spindle sensitivity Alpha motor Gamma motor neuron activity neuron activity Intrafusal fibers contract and Voluntary muscle spindle is stretched flexion Spindle sensitivity is maintained Alpha-gamma coactivation  Alpha gamma coactivation Primary motor cortex Extrafusal muscle contraction Intrafusal muscle activation and shortening maintains spindle sensitivity Change in length activates muscle spindle  Properties of stretch reflex 1) Resists changes in muscle length (sets muscle tone). 2) Mono- and polysynaptic components. 3) Feedback from muscle spindles.  Properties of muscle spindles 1) Reports muscle length. 2) In parallel with extrafusal muscle fibers (does not contribute to the force of muscle contraction). 3) Ia primary: Detects changes in muscle length and some static length (nuclear bag fibers). 4) II secondary: Detects static length (nuclear chain fibers). 5) Intrafusal fibers: Maintain muscle spindle sensitivity. 6) Alpha-gamma coactivation.  Spinal reflexes 1) Withdrawal reflex: protects limbs from injury 2) Stretch reflex: controls muscle length a) monosynaptic (primary) b) polysynaptic (secondary) 3) Inverse stretch reflex: controls muscle tension  Golgi tendon organ responds to tension In series with the muscle. Increase tension Active contraction of a muscle produces more tension than stretching  Golgi tendon organ Muscle fibers Capsule Ib afferent Free nerve endings Collagen fibers Tendon  Golgi tendon organ reflex (inverse stretch) Ib - Increased afferent + activity from Golgi Inhibition of motor tendon organ neurons innervating the ipsilateral extensor Increased tension in the extensor muscle Excitation of motor neurons innervating the ipsilateral flexor Activation of Golgi tendon organ  Properties of Golgi tendon organ 1) Reports muscle tension. 2) In series with extrafusal muscle fibers. 3) Ib afferents. 4) Underlies inverse stretch reflex (polysynaptic).  Motor control involves many brain areas Consciously initiate movement Middle level 1) Executes the individual muscle contractions. Corticospinal 2) Makes corrections (skilled movements) based on sensory information. Extrapyramidal (trunk & posture) Muscle spindle & Golgi tendon organ Voluntary movements have an “involuntary” component  Voluntary control of movement Primary motor cortex Somatosensory Premotor cortex cortex Consciously initiate a movement Central sulcus Sensorimotor cortex  Organization of primary motor cortex Somatotopic map Legs Primary motor cortex Arms Central Head sulcus Somatosensory cortex Primary motor cortex  Somatotopic motor representation 1) Systematic relationship between select muscle groups and the body areas they control. 2) Size of body structures in primary motor cortex is proportional to the number of neurons dedicated to their motor control. 3) Size of body structures in primary motor cortex is proportional to the degree of skill required to operate that area of the body.  Motor control involves many brain areas Consciously initiate movement Middle level 1) Executes the individual muscle contractions. Corticospinal 2) Makes corrections (skilled movements) based on sensory information. Extrapyramidal (trunk & posture) Muscle spindle & Golgi tendon organ Voluntary movements have an “involuntary” component  Direct cortical control of movement Corticospinal (skilled movements) Extrapyramidal Crossing in the Medulla (trunk & posture) To skeletal Alpha & gamma motor muscle neurons  Descending motor pathways Corticospinal 1) Originates in primary motor cortex (precentral gyrus). 2) Compact, discrete fiber tract direct to spinal cord. 3) Crossed: Controls contralateral muscles. 4) Extremities: Predominantly hands and feet. 5) Controls skilled voluntary movements. Extrapyramidal 1) Originates from neurons in brainstem. 2) Diffused and indirect: Several descending tracts via the brainstem. 3) Crossed and uncrossed. 4) Trunk and postural muscles. 5) Controls upright posture, balance, and walking.  Muscle tone Resistance of skeletal muscle to stretch. Normal subject: Slight and uniform. Damage to descending pathways 1) Hypertonia: Abnormally high muscle tone. 2) Spasticity: Overactive motor reflexes. 3) Rigidity: Constant muscle contraction. Damage to motor neurons 1) Hypotonia: Abnormally low muscle tone. 2) Atrophy: Loss of muscle mass. 3) Decreased or missing reflexes.  Motor control involves many brain areas Consciously initiate movement Helps to determine the specific sequence of movements needed to Corticospinal accomplish a desired action. (skilled movements) Extrapyramidal (trunk & posture) Muscle spindle & Golgi tendon organ Basal nuclei (ganglia) Basal nuclei  Basal nuclei movement disorders Parkinson disease One of the most common movement disorders. Reduced dopamine input to the basal nuclei. 1) Akinesia: Reduced movements 2) Bradykinesia: Slow movements 3) Muscular rigidity 4) Resting tremor (contrast with cerebellar deficits) Treatment includes increasing dopamine concentrations in the brain. Huntington disease Genetic mutation that causes widespread loss of neurons in the brain. Shows up later in life. Neurons in the basal nuclei are preferentially lost. 1) Hyperkinetic disorder: excessive motor movements 2) Choreiform movements: jerky, random involuntary movements of limbs and face Deep brain stimulation  Mike Robbins https://www.understandinganimalresearch.org.uk/resources/video-library/parkinsons-disease/  Motor control involves many brain areas Consciously initiate movement Corticospinal (skilled movements) Movement timing, planning, and error correction. Extrapyramidal Learning new motor skills. (trunk & posture) Muscle spindle & Golgi tendon organ  Cerebellum Brainstem Receives sensory information: vestibular, visual, auditory, somatosensory, proprioceptive. Cerebellum contains almost half of the brain’s neurons.  Cerebellar deficits 1) Asynergia: Smooth movements are subdivided into their separate components. 2) Dysmetria: Unable to target movements correctly “past pointing”. 3) Ataxia: Incoordination of muscles groups (awkward gate). 4) Intention tremor: During voluntary movements. 5) No paralysis or weakness.  Motor control involves many brain areas Consciously initiate movement Middle level 1) Executes the individual muscle contractions. Corticospinal 2) Makes corrections (skilled movements) based on sensory information. Extrapyramidal (trunk & posture) Muscle spindle & Golgi tendon organ Voluntary movements have an “involuntary” component