Basic Brain Anatomy and Localisation of Function Flashcards
NERVOUS SYSTEM STRUCTURE
CENTRAL NERVOUS SYSTEM (CNS)
- spinal cord
- brain (brain stem; cerebral hemispheres (cortex/sub-cortical structures/white-matter tracts)
PERIPHERAL NERVOUS SYSTEM (PNS)
- somatic nervous system
- autonomic nervous system (sympathetic/parasympathetic nervous systems)
NSS DEVELOPMENT
- begins developing at 2 weeks
- starts as small cell group that slowly thickens
- differentiates into forebrain/midbrain/hindbrain
- folds over itself
- forebrain -> cortex; midbrain -> thalamus close to brainstem at centre; hindbrain -> cerebellum
FUNCTIONAL CEREBRAL CORTEX AREAS
- visual area (sight/image recognition/perception)
- association area (STM/equilibrium/emotion)
- motor function area (initiation of voluntary muscles; eye movement/orientation)
- Broca’s area (speech muscles)
- auditory area (hearing)
- emotional area (pain/hunger/fight VS flight)
- sensory association area
- olfactory area (smelling)
- sensory area (muscle/skin sensation)
- somatosensory association area (weight/texture/temp evaluation ie. object recognition)
- Wernicke’s area (written/spoken language comprehension)
- higher mental functions (concentration/planning/judgement/emotional expression/creativity/inhibition)
FUNCTIONAL CEREBELLUM AREAS
- motor function (movement coordination; balance/equilibrium; posture)
RIGHT CEREBRAL HEMISPHERE
CORPUS CALLOSUM
- white matter tracts (numerous axons) connecting the 2 hemispheres
BRAIN STEM
CORTEX/SULCI/GYRI
CORTEX - outer brain grey matter; white matter (long elongated nerve cells-axons) underneath - made of bodies of nerve cells-neurons GYRI - plateau on cortical surface SULCI - fold/ditch in cortical surface - major sulci often referred to as fissures
CORTICAL GREY/WHITE MATTER
- body/soma of neuron w/dendrites = grey matter
- axon (covered in protective myelin) of neuron = white matter; bright via hue of myelin
CORPUS CALLOSUM
- white matter tracts (numerous axons) connecting the hemispheres
- intercallosal transfer = electrical impulses that travel from neurons in one hemisphere to neurons in the other via corpus callosum
MAJOR SULCI/FISSURES
SYLVIAN/LATERAL FISSURE
PARIETO-OCCIPITAL SULCUS
CENTRAL SULCUS/FISSURE OF ROLANDO
THE LOBES
FRONTAL
PARIETAL
OCCIPITAL
TEMPORAL
MAJOR GYRI
SUPERIOR FRONTAL/TEMPORAL MIDDLE FRONTAL/TEMPORAL INFERIOR FRONTAL/TEMPORAL PRECENTRAL POSTCENTRAL SUPRAMARGINAL ANGULAR LATERAL OCCIPITAL
CYTOARCHITECTURE
BRODMANN (1868-1918)
- cortical regions vary in the detailed cellular structure (neuron types)/arrangement (layers/density)
- used as criterion; cortex divided into areas; many turned out to serve specific functions (ie. primary visual/auditory cortices/primary motor cortex):
PARIETAL CORTEX
STRIATE CORTEX
MOTOR CORTEX
COORDINATES/ORIENTATIONS
ANTERIOR (ROSTRAL) SUPERIOR (DORSAL) POSTERIOR (CAUDAL) INFERIOR (VENTRAL) LATERAL (L/R) MEDIAL SUPERIOR/INFERIOR
SLICES
AXIAL - from the top CORONAL - from the back SAGITTAL - from the side
ARE FUNCTIONS LOCALISED?
- early thinkers like phrenology movement; thought function = highly localised
- 19th century animal exps showed that basic physiological regulation functions (breathing/circulation) = localised in brain stem; balance control = cerebellum
- BUT couldn’t localise cog functions; concluded that different brain parts may be equally involved regarding these functions
BASIC PROCESSES
- physiological/metabolic processes controlled via neuron groups in brainstem/thalamus/hypothalamus
- include: respiration/digestion/glucose metabolism/arousal/body temp regulation/blood pressure/swallowing/coughing/sneezing/vomiting/circadian rhythms
CONTROL OF BASIC PHYSIOLOGY
- specific neuron groups include:
RETICULAR FORMATION - complex cell network in brainstem core involved in arousal/sleep control
SUPRACHIASMATIC NUCLEUS (HYPOTHALAMUS) - controls circadian (24h) biological rhythms
VENTROMEDIAL NUCLEUS (HYPOTHALAMUS) - controls conversion of blood glucose to body fat
RAS (RETICULAR ACTIVATING SYSTEM)
- determines level of alertness
PERCEPTION HIERARCHICAL ORGANISATION
- primary visual/auditory/sensory-motor areas = cortical areas where sensory info arrives (via relay nuclei in brainstem; mostly thalamus) ->
- secondary sensory areas = more sophisticated processing ->
- association areas = info from dif modalities/types is integrated
- thalamic nuclei = relays for sensory info
VISUAL PERCEPTION HIERARCHICAL ORGANISATION
- visual processing segregated into:
WHAT PATH - specialised in analysis of stimulus features (colour/shape)
WHERE PATH - specialised in rapid detection of stimulus location/motion
MOTOR CONTROL HIERARCHICAL ORGANISATION
- control of movement
- primary motor cortex = exerts direct movement control
- premotor/supplementary motor = involved in movement planning/motor beh integration w/others
- basal ganglia (sub-cortical)/cerebellum/substantia nigra (brainstem/cell groups) = involved in fine-grained coordination/movement timing
MOTOR AREAS (BRODMANN 4/6/8)
AREA 5/7 - posterior parietal cortex AREA 4 - M1/primary area AREA 6 - SMA/PMC AREA 8 - secondary areas/SMA
BASAL GANGLIA & CEREBELLUM
BASAL GANGLIA - caudate nucleus (striatum) - putamen (striatum) - globus pallidus - subthalamic nucleus - substantia nigra CEREBELLUM - cerebrum - spinal cord - deep cerebellar nuclei
CORTICAL HOMUNCULUS
MOTOR CORTEX
- swallowing/tongue/jaw/lips/face/eye/brow/neck
- fingers/thumb/hand/wrist/elbow/arm/shoulder
- trunk/hip/knee/ankle/toes
SOMATOSENSORY CORTEX
- tongue/jaw/teeth/gums/lips/face/nose/eye/head
- thumb/fingers/hand/arm/shoulder/neck
- trunk/hip/knee/leg/foot/toes/genitals
