Neuroscience Flashcards
Where is the homunculus located?
On either side of the central gyrus (separates frontal & parietal lobes)
Where is the cerebellum located?
Underneath cerebrum, behind the brain stem
What are the 3 types of movements?
- Reflex
- Rhythmic motor patterns (automatic, e.g. chewing, walking)
- Voluntary movement (require conscious control)
What does movement require?
- Sensory info coming in
- Processing of info at an automatic and/or cognitive level
- Executing a response with the correct amount/timing of muscle activity
- Ability to rapidly modify response
- Learning & memory
Where does sensory info come from?
- Visual
- Vestibular
- Somatosensory (including tactile & kinaesthetic sensation)
What is the function of the visual system?
- Sight
- Eye movement control
- Info for postural and limb movement
What is the visual system made up of?
- Retina
- Afferent pathways (optic nerve, thalamic/vestibular connections, cortical connections for perception)
- Efferent connections (eye movements)
What are the 3 pathways that transmit visual info to the CNS?
- Lateral geniculate of thalamus
- Occipitotemporal region (visual object identification)
- Posterior parietal cortex (visual guidance) - Tectum
- Visually guided eye movements (orientation) - Pretectal area
- Pupillary reflexes
What are the functions of the vestibular system?
- Provides info about direction & speed of head movement
- Position of head relative to gravity
- Gaze stabilisation
- Postural adjustments
- Autonomic function & consciousness
What is the vestibular system made up of?
- Vestibular apparatus/labyrinths (semicircular canals, utricle & saccule located in inner ear)
- Afferent connections (vestibular nerve, connections to vestibular nuclei & cerebellum)
What are the functions of the vestibular apparatus/labyrinths?
Semicircular canals
- Directional specific, acceleratory forces
- Give 3D picture
Otoliths (utricle & saccule)
- Respond to vertical/linear displacement
- Respond to gravity
What is the main vestibular afferent pathway?
Vestibular nerve
- Vestibular nuclei in medulla/pons
- Flocculonodular lobe of cerebellum
What is the central vestibular system made up of?
- 4 nuclei
- 6 pathways
- Vestibulocerebellum
- Vestibular cortex
What does somatosensation include?
- Touch
- Pain
- Temperature
- Vibration
- Proprioception
What contributes to somatosensation?
- Receptors
- Somatosensory pathways
- Conscious relay pathways
How is afferent somatosensory information transmitted?
- Ascending sensory pathways
- Important connections in brain stem, thalamus
- Important cortical regions (perception)
What are the different types of sensory pathways?
Conscious relay
- Location/type of stimulation
- Accurate/discriminative info
Divergent
- Transmit to many locations
- Conscious & unconscious
Unconscious relay
- Proprioceptive/movement related info
- Automatic adjustments of movement/posture
What are the ascending sensory pathways?
- Dorsal columns
- Anterior & lateral spinothalamic
- Spinocerebellar: Unconscious movement-related info
What are the features of the dorsal columns?
- 3-neuron relay pathway
- Decussates in medulla
- Discriminative touch, conscious proprioception
What are the features of the spinothalamic tracts (anterolateral columns)?
- 3-neuron relay pathway
- Decussates in spinal cord
- Conscious discriminative pain & temp
- Also includes divergent pathways for slow aching pain
What are the features of the spinocerebellar tract?
- Unconscious movement related info
- Two pathways (posterior, cuneo)
- Also includes internal feedback tracts
What are the features of the internal feedback tracts of the spinocerebellar tract?
- Convey info for spinal reflexes
- Anterior spinocereballar (auto coordination of lower limbs)
- Rostrospinocerebellar (auto coordination of upper limbs)
What are the 3 relay areas of the brain?
- Medial lemniscus
- Internal capsule
- Corpus collosum
What is the function of the medial lemniscus?
- Crossing of 2nd order neurons of dorsal columns
- Sensory decussation
- Relay to the VPL nucleus of thalamus
What is the function of the internal capsule?
- 3 parts (posterior limb, genu/cranial nerve links, anterior limb)
- Connects cortex with sub cortex structures (brainstem, thalamus)
- Ascending & descending axons
What is the function of the corpus collosum?
- Connects hemispheres
- Allows for inter-hemispheric communication
What are the main integration centres involved with movement?
- Thalamus
- Cerebral cortex
- Vestibular nuclei
- Basal ganglia
- Cerebellum
- Spinal cord
What are the features of the thalamus?
- Part of diencephalon
- Collection of nuclei
- Selective filter for the cortex
What are the main functions of the thalamus?
- Integration of sensory info
- Regulates consciousness, arousal & attention
- Processes emotional & some memory info
What are the 5 main areas of the cerebral cortex?
- Primary sensory cortex (receives info)
- Sensory association cortex (recognises sensation)
- Association cortex (interpretation)
- Motor planning areas (movement composition)
- Primary motor cortex (coordinates movement)
What is the function of the primary sensory cortex?
- Discriminates size, texture, shape of objects
- Receives info directly via thalamus
What is the function of the sensory association cortex?
- Analyses info from primary sensory cortex/thalamus
- Provides stereogenesis & memory of tactile/spatial environment
What is the function of the pre-motor cortex of the motor planning areas?
- Controls trunk/girdle muscles
- Anticipatory postural adjustments
- Involved in selecting motor programs based on sensory input/association
What is the function of the supplementary cortex of the motor planning areas?
- Initiates movement
- Orientation
- Planning bimanual & sequential movements
What is the function of the primary motor cortex?
Voluntarily controlled movement
What are the 3 areas of the association cortex?
- Pre-frontal
- Parieto-temporal
- Limbic
What is the function of the association cortex?
- Personality
- Integration/interpretation
- Processing memory
- Generation of emotion
- Intelligence
- Self-awareness
- Executive functions
What are the features of the vestibular nuclei?
- 4 nuclei: Deiter’s, medial, inferior, superior
- Part of pons/medulla
- Sensory integration (visual, proprioceptive, tactile, auditory info)
- Motor control of eyes & posture
What are the features of the basal ganglia?
- 4 nuclei: Striatum, globus pallidus, subthalamic nuclei, substantia nigra
- Located in middle of brain near thalamus
- Crucial link between idea of movement and doing movement
What are the motor functions of the basal ganglia?
- Amplitude, speed, initiation of movement
- Allows sequential, simultaneous tasks
- Muscle tone/force
- Selects/inhibits specific motor synergies
What are the cognitive functions of the basal ganglia?
- Working memory
- Sustained attention
- Ability to change behaviour with tasks
- Motivation
What is the structure of the cerebellum?
- Three lobes: Anterior, posterior, flocculonodular
- Three functional vertical divisions: Vestibulocerebellum, spinocerebellum, cerebrocerebellum
What are the functions of the 3 functional divisions of the cerebellum?
Vestibulocerebellum:
- Equilibrium of movement
- Flocculonodular lobe
Spinocerebellum:
- Gross limb movement
- Vermis & paravermal regions
Cerebrocerebellum:
- Distal limb movement
- Lateral cerebral hemispheres
What is the overall function of the cerebellum?
- Fine tune motor commands to make movement supple, graceful, coordinated
- Compare actual motor output to intended output
What is the function of the spinal cord?
- Simple reflex responses
- Integrates activity from all sources
- Adjusts motor LMNs output via common spinal interneurons
What connects lower motor neurons (LMNs) to the brain?
Descending motor pathways (efferent)
- Corticospinal
- Corticobulbospinal
- Rubrospinal
- Reticulospinal
- Vestibulospinal
