Brain Development Nervous Systems
Nervous system Centralnervoussystem Peripheralnervoussystem Spinalcord Sensorypathways Motorpathways Brain Somatic(voluntary)nervous system Autonomic(involuntary)nervous system • Sympathetic • arousal & energy production • “fight or flight” • Parasympathetic • calming & back to maintenance • “rest & digest” Sympatheticdivision Parasympatheticdivision
Types of neurons cell body sensory neuron cell body axon interneuron “associative” dendrites dendrites cell body motor neuron
associative neurons nerve cords radial nerve nerveribs nerve net FlatwormPlatyhelminthes Cnidarian Echinoderm Cephalization = Brain evolution • Cephalization= clustering of neurons in “brain” at front (anterior) end of bilaterally symmetrical animals where sense organs are More organization but still based on nerve nets; supports more complex movement Simplest, defined central nervous system more complex muscle control Simplest nervous system no control of complex actions
giant axon central nervous system brain brain ventral nerve cords peripheral nerves Mollusk Earthworm Arthropod Cephalization = Brain evolution • increase in interneurons in brain region More complex brains connected to all other parts of body by peripheral nerves More complex brains in predators most sophisticated invertebrate nervous system Further brain development ganglia = neuron clusters along CNS
Shark Frog Crocodile Cat Human Spinal cord Hind: Medulla oblongata Hind: Cerebellum Optic tectum Bird Midbrain Fore: Cerebrum Olfactory tract Evolution of vertebrate brain forebrain forebraindominant cerebrum hindbrain forebrain
Human brain
Functional divisions of brain • Hindbrain • evolutionary older structures of the brain • regulate essential autonomic & integrative functions • brainstem • pons • medulla oblongata • midbrain • cerebellum • thalamus, hypothalamus
Brainstem • The “lower brain” • medulla oblongata • pons • midbrain • Functions • homeostasis • coordination of movement • conduction of impulses to higher brain centers
Medulla oblongata & Pons • Controls autonomic homeostatic functions • heart & blood vessel activity • breathing • swallowing • vomiting • digestion • Relays information to & from higher brain centers
Midbrain • Involved in the integration of sensory information • regulation of visual reflexes • regulation of auditory reflexes
Reticular Formation • Sleep & wakefulness produces patterns of electrical activity in the brain • recorded as an ElectroEncephaloGram (EEG) • most dreaming during REM(rapid eye movement) sleep
Cerebrum • Most highly evolved structure of mammalian brain • Cerebrum divided • hemispheres • left = right side of body • right = left side of body • Corpus callosum • major connection between 2 hemispheres
Lateralization of Brain Function • Left hemisphere • language, math, logic operations, processing of serial sequences of information, visual & auditory details • detailed activities required for motor control • Right hemisphere • pattern recognition, spatial relationships, non-verbal ideation, emotional processing, parallel processing of information
Cerebrum specialization • Regions of the cerebrum are specialized for different functions • Lobes • frontal • temporal • occipital • parietal
Limbic system Mediates basic emotions (fear, anger), involved in emotional bonding, establishes emotional memory Amygdala involved in recognizing emotional content of facial expression
Simplest Nerve Circuit • Reflex, or automatic response • rapid response • automated • signal only goes to spinal cord • no higher level processing • adaptive value • essential actions • don’t need to think or make decisions about • blinking • balance • pupil dilation • startle
Eye Blink or Pain Withdrawal Reflex Gray matter Interneuron Stimulus White matter Receptor in skin Sensory neuron Motor neuron Spinal cord Effector (muscle)
cerebrum cerebellum spinal cord cervical nerves thoracic nerves lumbar nerves femoral nerve sciatic nerve tibial nerve Any Questions??
