Test 1 NEURO chap. 3,5,6

How is sensory info integrated

• Automatically without conscious effort

• Based on senses (sight, hearing) & somatosensory system (skin and muscles)

Feedback

Sensory info received during movement

Feedforward

Sensory info obtained from experience (anticipatory)

Motor learning

• Info from body and environment (sensory intake)

• Processing the info (sensory integration - CNS cooking)

• Planning and organizing behavior (output)

Age related sensory changes

• Decrease in myelin of the CNS & PNS, decrease nerve conduction velocity

• Neuron degeneration

• Decrease in synthesis of dopamine and norepinephrine

• Decrease joint range, pain and muscle weakness

Alert

Awake and attentive

Lethargic

Drowsy, may fall asleep

Obtunded

Difficult to arouse, confused

Stupor

Respond only to strong stimulus

Coma

Cannot be aroused “true coma”

Ascending tracts

Carry sensory info to the brain

• DCML (Dorsal column medial lemniscus)

• Anterolateral spinothalamic tract

Descending tracts

Carry motor commands from the brain to muscles

• Corticospinal tract: voluntary movement

• Vestibulospinal tract: balance and posture

Anterolateral spinothalamic tract

• Sensation: non discriminative (pain, temp), crude localization, poor intensity discrimination, poor spatial orientation relative to origin of stimulus

• Afferent fibers: small diameter, slowly conducting

• Origin: skin

Dorsal column medial lemniscus

• Sensation: Two point discrimination, precise localization, fine intensity gradations, high degree of spatial orientation relative to origin of stimulus.

• Afferent Fibers: large, rapidly conducting 

• Origin: skin, joints, tendons, specialized mechanoreceptors

Hypesthesia (hypoesthesia)

Reduced sensation to stimulus

Anesthesia

Complete loss of sensation

Hyperesthesia

Increased sensitivity to sensory stimuli

Paresthesia

Abnormal sensation

Dysesthesia

Distorted or unpleasant sensation to normal stimuli

Allodynia

Pain from a stimulus that shouldn’t cause pain

Hyperalgesia

Increased pain response to a normally painful stimulus

Analgesia

Absence of pain sensation

Proprioception loss

Impaired awareness of body position and movement

Kinesthesia loss

Impaired awareness of movement

Graphesthesia loss

Inability to recognize writing on the skin by touch

Stereognosis loss

Inability to recognize objects by touch

Neglect syndrome

Ignoring one side of the body or environment (common in stroke)

Hemianopia

Loss of half the visual field

Quadrantanopia

Loss of one quadrant of the visual field

Scotoma

Partial loss of vision or a blind spot

Motor control

Neural, physical and behavioral process

• results in posture and movement

Motor learning

Change in the capability of a person to perform a skill which occurs as the result of skilled practice or experience

How does motor learning occur

Complex process that requires spatial, temporal and hierarchical organization within the CNS (varies due to genetics and life experiences)

Motor program

Abstract representation that results in the production of a coordinated movement sequence (walking or standing)

Motor plan

An idea or plan for purposeful movements made up of several motor programs

Motor memory

Recall of motor programs

Dynamical systems control theory

• Units of the CNS are organized around specific task demands

• Entire CNS may be necessary with complex tasks while small parts needed for simpler tasks

• Command levels depend on task being executed

Hierarchical control theory

• Organization of CNS into higher, middle, and lower levels

• Top-down control

• As skill progresses, control is systematically shifted to lower level processing

Highest hierarchal control theory

Association cortex and portions of the basal ganglia

• Organizes sensorimotor info and responsible for decision making

Middle hierarchical control theory

Sensorimotor cortex, cerebellum, basal ganglia, and brainstem

• Shape and define motor programs and initiate commands

Lowest hierarchical control theory

Spinal cord

• Executes the commands into final muscle actions

Ascending reticular system

In the brainstem acts on the cortex to maintain the conscious state, and control the different degrees of wakefulness

Descending reticular activating system

Functions to maintain autonomic and somatic motor systems (monitoring body functions and homeostasis)

Minimally conscious state (Vegetative state)

Irregular sleep/wake cycles, normalized respiration, digestion and blood pressure (temp) regulation

Persistent vegetative state

Usually caused by a severe head injury or anoxia, lasts more than a year

Glasgow coma scale (GCS)

• The gold standard for coma assessment.

• Evaluates eyes opening, best motor response and verbal response.

Tone

Resistance of muscle to passive elongation while muscle relaxation

• Should have a residual amount of contraction based on

  • physical inertia

  • intrinsic mechanical stiffness

  • reflex muscle contraction

Hypertonia

Tone increased beyond normal

Hypotonia

Tone decreased below normal

Dystonia

Impaired/disorderly tone

Spasticity

• Hypertonicity that is velocity dependent. Part of an upper motor neuron syndrome corticofugal pathways 

• Due to loss of inhibitory control (presynaptic) and over excitability of alpha motor neurons

Clonus

Twitching at certain ROM

Babinski sign

DF of great toe with fanning go the other toes

Decerbrate

Upper and lower limb extend

Decorticate

Upper limb flex, Lower extend

Coordination

Smooth, accurate controlled motor response

• dependent upon an intact neuromuscular system

Movements

Appropriate speed, distance, timing, and muscle tension

Balance

Maintain posture and stability

Linked dx w/ coordination

• TBI

• PD

• MS

• Huntington Disease

• CP

• Sydenham Chorea

• Vestibular Pathologies

Corticospinal (pyramidal) tract

Skilled, fine motor control, especially of distal limbs

Corticobulbar tract

Cranial nerve function

Tectospinal tract

Guides head movement during visual motor task

Reticulospinal tract (medial & lateral)

Muscle tone and reflex activity; important to posture and gait

Vestibulospinal tract

Postural/head control and coordination of head and eye movements

Rubrospinal tract

Primitive tract that joins with corticospinal tract. Mostly insignificant contribution

Role of the cerebellum

Error correcting mechanism and a comparator

What does the cerebellum regulate

• movement

• posture control

• muscle tone

• motor learning

Coordination impairments due to cerebellum

• Ataxia

• Dysmetria

• Dysdiadochokinesia

• Intention tremor

• Hypo/hypertonia

• Dyssynergia

• Asynergia

• Dysarthria

• Nystagmus

• Rebound phenomenon

• Astenia

Role of the basal ganglia

• Initiation and regulation of gross intentional movements

• Planning and execution of complex motor responses

• Facilitation of desired motor responses

• Inhibiting unwanted movements

Coordination impairments due to basal ganglia

• Bradykinesia

• Rigidity

• Tremor

• Akinesia

• Chorea

• Athetosis

• Choreathetosis

• Hemiballismus

• Hypokinesia

• Dystonia