Neurological Development

1. Neurological Development Neurobiology of Learning Differences JHU Drs. Denckla and Lewis

2. Agenda • PHASE ONE • The Brain…what’s in it, how does it develop, how does it work, and what threatens its functions? • PHASE TWO • Learning…what goes into the process as we progress through school to adulthood?

3. TBQ… Why do teachers in 21st century have to have knowledge of brain function and dysfunction in order to competently offer instruction?

4. PHASE ONE • The Brain • How does it develop? • what does it do? • what is it like? • how does it operate?

5. Prenatal Development • By 6 – 7 months of 9, 70% of brain cells are in cerebral cortex • Genetic blueprint for cortex folding similar but subtly individual

6. Cellular Migration • Other cells’ axons or glia guide directions • Chemicals also act as “GPS” • 97% of cells go correctly

7. Getting Connected, Time-Sensitive • Aggregation by biochemical and receptor similarities • Sprout axons (outgoing) • Sprout dendrites (incoming) • Preprogrammed targets • Axon + Dendrite=Synapse

8. Strengthening Connections • Chemotrophic attractants • Stimuli even in utero • Fetus kicks, sucks thumb, increases motor connections • Fetus hears, increases specific auditory connections

9. Pruning overlaps Proliferation • Not much below cerebrum • Half of cortical motor neurons die • Possibly lack of “good” connections “starves” neurons

10. Myelination in Last 2 Months • Like insulation of electric wires • Speeds signal transmission • Prenatal: motor & sensory axons • Prolonged postnatal process

11. Postnatal Shaping of Brain • Networks of synapses activate • By age 3 yrs each neuron connects up to 10k others • “Use it or lose it” begins • But-timely experiences, during critical periods, yield the best results

12. Brain Growth 0 to 3 yrs • Few cells added, but existing cells enlarge and sprout axons & dendrites • Inputs and synapses grow reciprocally and selectively • Age two is “blooming buzzing confusion,” the new outruns the pruning of the old

13. Boy Brain or Girl Brain? • From 20 week fetus to puberty, girls 20% faster developers • Interhemispheric connections at 3 levels, larger in women

14. Paradox of Preschool Learning • Not much episodic (personal history) memory before 3-4 • Cause is lack of hippocampus connectivity to cortex • Lots learned procedurally • Language is somewhat special still, somewhat mysterious

15. School-Age Brain • Right hemisphere is ahead of left (and girls 20% ahead) • Most of school is left-based • Long cerebral pathways myelinate within large range (e.g. 3 to 10 yrs “normal”) • Connecting R and L: late bloomers?

16. Adolescent Brain • Hormones increase synaptic pruning • Hormones stir up emotional brain • Amygdala enlarges • Frontal lobe connections myelinate • If timing is off, impulsivity wins! • Attention/correction matures via anterior cingulate gyrus • Corpus callosum myelinates

17. What do we know about the brain? • The environment influences how the brain develops • The brain changes with every experience we have and in early years is necessary for development • Second languages and music are learned more efficiently in the first decade of life

18. What do we know about the brain? • Brain development is integrated – not one system then another • Critical periods in development allow optimal learning • Learning is strongly influenced by emotion • Brain chemistry effects mood, personality and behavior

19. Lateral View of the Brain Frontal Lobes – site of executive functions of the brain Parietal Lobes – site of orientation, calculation and some recognition skills Occipital Lobes – Site of visual processing skills Temporal Lobes – site of sound,speech and some memory skills.

20. Midline View of the Brain Limbic system – center of emotional & reasoned responses Thalamus – receptor of sensory input (not smell) and direction to other parts of the brain for processing. Amygdala – sensory center of rage, fear and pleasure Hippocampus – converts information from working memory to long term memory

21. Midline View of the Brain Corpus Callosum – “cable” of the brain; serves as a bridge between the hemispheres Cerebellum – “little brain”, monitors impulses and coordinates physical responses; has important role in learning, timing, and performing motor tasks Frontal cortex – monitors higher order thinking, problem solving, regulates excesses in reactions

22. Visual Pathway of the Brain Objects are perceived and the thalamus sends the perceived image to the correct processing center of the brain – in this case to the occipital lobe (location of the visual cortex) via the optic nerve. The visual cortex is a primary area of response and that response is then connected to other processing areas, such as the memory center. The right side of the perceived image is transmitted to the left occipital cortex and the opposite occurs on the left. Damage in the visual cortex may cause a failure in transmission of the perceived message. One’s eyes may be fine, and yet one may not “see”.

23. Auditory Pathway of the Brain Broca’s area relates to processing oral language in initiation or response. Objects are perceived and the thalamus sends the perceived message to the correct processing center of the brain – in this case, the temporal lobe, for discrimination. Wernicke’s area relates to the processing of incoming auditory language for understanding.

24. Neurotransmitters • The brain’s chemical signals are well known to researchers, and are known as neurotransmitters. • Neurotransmitters are either excitatory or inhibitive, meaning they control the increase or decrease of neuronal activity. • Among the most commonly known are acetylcholine, dopamine, seratonin, and the endorphins.

25. AMINES ACETYLCHOLINE controls movement & memory ADRENALINE (EPINEPHRINE) puts body in a state of alert DOPAMINE enhances pleasurable feelings NOREPINEPHRINE too much= manic responses too little= depressed responses SERATONIN oldest neurotransmitter relates to sleep PEPTIDES CORTISOL emitted in “fight or flight” response too much= deteriorates other areas ENDORPHINS suppress pain sensation VASOPRESSIN related to control of blood pressure Neurotransmitters (selected)

26. Synapses and Neurotransmitters • The juncture of the axon of one neuron and that of another is called a synapse. • The regulatory or electrical signal from the axon stimulates the release of the neurotransmitter into the synaptic cleft, the tiny space between the neurons, which converts into a chemical signal. • Once received into the next neuron, the chemical signal converts back to an electrical signal, which is sent down the dendrite spine to trigger a reaction.

27. Language areas Broca’s Area controls the expression of vocabulary, syntax and grammar; it is about the size of a quarter and is located at the left temple region Wernicke’s Area is the gateway to the comprehension of language as it is presented to the listener/reader; it is about the size of a silver dollar and is located above the left ear Parietal area associates “meaning”

28. Integration of Systems • The successful integration of all areas of the brain, including the chemical systems, results in successful movement, memory and permits new learning.

29. Mirror Neurons/Social Learning • Newborns (42 minutes old) match orofacial movements shown to them, “share representations for self and others” • Closely linked to language acquisition • Shared neural circuitry for perception and production • 6 month old infants listening to speech activate both Wernicke’s and Broca’s

30. seizures or epilepsy traumatic brain injury psychiatric illness environmental toxins genetic disorders emotional/behavioral disorders attention deficits learning disabilities autism spectrum disorder coordination disorders communication disorders Your students may come to school with any of these conditions

31. All of these learning elements are centered in the brain • Working memory • Long term memory • Receptive language • Expressive language • Attention/Concentration • Organization/Planning • Psychomotor skills • 2 kinds of visual perception

32. So…what is your answer? Why do teachers in 21st century have to have knowledge of brain function and dysfunction in order to competently offer instruction?