Biological Foundations

1. Biological Foundations Can they inform education?

2. Brain & Education • A bridge too far? • Neuromyths • Critical periods • Modularity • Increase in synapses from infancy to late childhood • Enriched environments cause new synapses to form • Right brain versus left brain (or male versus female brains)

3. electrical & chemical What are neurons and synapses? From Fischbach in Mind and Brain

4. Myelination • Myelin – fatty sheath that insulates both peripheral and central nerve fibers in mammals. • Correlations (not cause  ): myelination makes a difference at grosser levels than the cell level.

5. Special-purpose neurons? • By the 16th week after gestation particular neurons have assumed specific functions and migrated to specific regions of the brain. Thus, some “fixed circuitry.” • Experience-expectant synapses • Genetically programmed to be sensitive to particular stimuli. There must be experience for these to develop. • Experience-dependent synapses • Not genetically predetermined. They stabilize in reaction to unique environmental stimulation that an individual encounters.

6. Are things built in? • Is language innate? • May be some preprogrammed elements – one being the potential to learn language. • Language learning proceeds uniformly within a linguistic community • Children do not seem to copy what they hear (difficult to explain what they do without some innate component) • Children do not make particular kinds of mistakes. • Neurological age is a critical factor in language learning. • This does not mean that a language in particular or language in general is built into a child.

7. ? Thought question ? • Goswami (2004) stated, “Nevertheless, neurons themselves are interchangeable in the immature system and so dramatic differences in the environment can lead to different developmental outcomes” (p. 4). Does this seem like a reasonable claim given experience-expectant and experience-dependent synapses?

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9. Plasticity • The rule rather than the exception. • But, does seem to decline as we age. May “be a function of mature individuals committing increasing portions of their nervous system to memory storage” (Driscoll, p. 297).

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11. Cerebral cortex • Grayish brown. • Large sheet of layered neurons. • Cortext means bark. • Why is it crinkled? (to fit in our heads – rats have smooth brains, if ours were not crinkled we’d need gigantic heads) • Uncrinkled, the cortex is about the size of a dishtowel. The surface area is 2200-2400 cm2. 3mm thick on average (1.5-4.5 mm). • Has neurons, dendrites, some axons (the axons extend to other brain regions), and blood vessels.

12. Underlying regions • White. Mostly axons.

13. Hemispheres • Right hemisphere – More white matter (more mylination). Intuitive and visual. Motor skills, intuition, emotion, ready receptor of music and cadence. As a problem solver looks holistically. Some specific cases of language are processed here, but processed pictorally and graphically. Emotional tone of phrasing and voice.

14. Hemispheres • Left hemisphere – More gray matter. Considered to be analytical and verbal. Puts things in sequential, logical order. Articulation and grammar of speech. Sometimes called the dominant hemisphere since it houses the skills dominant in society.

15. Temporal lobe: Auditory processing (hearing and language) Parietal lobe: Attention, touch, pain, temperature, sense, limb position Limbic Lobe: Emotionalmemory, learning, and memory. Also olfactory. Frontal lobe: Front part—higher aspects of motor control, planning and execution of behavior, tasks that require integration of information over time. Occipital lobe: Vision (optic chiasm is where the information from the two visual fields are split and sent to different halves of the brain)

16. Hippocampus: Learning and memory—makes new memories, does not store them. Hypothalamus: Regulator of lower levels: heartbeat, BP, temperature for example. Corpus callosum: Connections between the two hemispheres. Cerebellum: Sensory, motor coordination, some cognition Brain stem area: Oldest part of the brain. The brain developed up and out. Thalamus: Relay station, major sensory gateway

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18. NS research • How do we know what we know? • Lesion studies • Imaging methods

19. X-ray CT Photo PET MRI From Posner & Raichle

20. Tools • EEG/ERP – electroencephalogram/event related potential • Accesses the electrical activity of the brain. • ERP – different waves means different activity • Used in studies that provide support for neural efficiency theory • Slow processes consume more capacity than do fast processes. • Capacity demanding tasks should seem less demanding for a more intelligent person compared to a less intelligent person.

21. Tools • CT scan – computer tomography • Shoots x-rays through the head at different angles, with the beams received by x-ray detectors on the opposite side of the head. • Can detect how much x-ray is absorbed. • Permits distinction between gray and white matter.

22. Tools • PET scan – positron emission tomography • Radioactive element is used (15O). Moves into the blood stream, more blood in active areas of brain, more “visible.” 15O has a short ½ life and gives off a positron. Positron moves a short distance and give off two gamma rays in opposite directions. Have to use the subtractive method. Problems: this is an indirect measure of blood flow. Gives good spatial resolution but only OK temporal resolution because blood flow itself is quite slow.

23. Tools • fMRI – Functional Magnetic Resonance Imaging. • Similar to PET, but uses radio frequencing information given off by water. • Changes in orientation of atomic nuclei in the molecules of the brain are induced and measured. • Gives better time and spatial resolution than PET and CT scans. Is more expensive.

24. Tools

25. An example. Blood flow response in visual cortices to the following stimuli: These are PET scans. Note the prominent responses in the left hemisphere to pseudowords and words as compared to letter strings and false fonts. From Posner & Raichle.

26. Hierarchical design of lexical access experiment From Posner & Raichle. Experiment done in conjunction with Peterson, Fox, & Mintum (1988)

27. Each of the tasks in the hierarchical experiment activates a distinct set of brain areas. The method of analysis includes the subtractive method.

29. The brain does seem to be modular. . .

30. Visual system Left: Normally, when an “a” is presented to the right visual field, the signal will travel to the left hemisphere and then over the corpus callosum to the right hemisphere. Right: When the corpus callosum has been severed, the information cannot be transferred to the right hemisphere.

31. Sectors of each eye’s visual field are colored in this diagram in order to illustrate how the lens of the eye inverts the image being viewed: the image falls on the retina in such a way that up is down and left is right. Signals from the right retinas (left visual field) of both eyes travel through the optic nerve, optic tract, and optic radiations to the primary visual cortex in the right hemisphere, whereas signals from the left retinas (right visual field) travel to the left hemisphere. From Posner & Raichle

32. Language B: In 1861 Broca treated a man who had suffered a stroke. He could understand speech, but could not talk. The impact of his finding was huge: a specific aspect of language could be impaired by a specific lesion to the left frontal lobe. A: In 1896, Wernicke had a patient with a lesion in a more posterior region of the left hemisphere, an area around the temporal and parietal lobes. This patient could talk freely, but what he said made little sense. These discoveries at the time were earth shattering: focal disease causes specific deficits. Pc: Area concerned with language. From Gazzaniga, Ivry, & Mangun (1998)

33. Motor and Sensory cortex Sensory receptors from each part of the body project to a specific area of the cortex (the somatic sensory cortex), and, similarly, a specific area of the cortex (the motor cortex) controls the movement from each body part. Thus, the cortex forms a map of the body surface, represented by the misshappen body parts. They are distorted not because the area of the cortex devoted to a body part being proportional to the size of the part, but rather to the precision with which it is sensed or controlled. Source: Posner & Raichle

34. Consider that the brain reflects with extended experience: • Skilled pianists • Skilled violinists • Skilled Braille readers • Experienced cab drivers in London From Gazzaniga, Ivry, & Mangun

35. Then again, how can it be modular?

36. Attention • Controlling attentional states • Lack of control seen frequently with frontal lobe damage • Lack or excessive neurotransmitter (catecholomines) • Selectively allocating attentional resources • Subcortical mechanism (including interactions between the hemispheres) • Hippocampus • Selectively organizing attention • Brain activity mapping, eye movement, priming studies. • Cerebral cortex is implicated but do not know exactly what systems. • Parietal lobe

37. Memory • Cell assemblies – memories are distributed and may share neurons • Types of memories • Procedural • Perceptual representation (visual and auditory word forms, structural description) • Semantic • Primary/working • Episodic

38. Language • Studies of normal adults grammatical processing more in the frontal regions of the left hemisphere, semantic and vocabulary learning activate posterior lateral regions of both hemispheres. • Late learners do not rely on the left hemisphere, but both. • Congenitally blind people have bilateralization

39. Reading • For both children and adults – major systems for reading alphabetic scripts are lateralized to the left hemisphere. • Alphabetic/orthographic processing – occipital, temporal, and parietal areas. • Visual features, letter shapes, orthography – occipital-temporal • Phonological awareness – temporo-parietal junction. • PET scans show that the functional organization of the brain differs between literate and illiterate adults.

40. Mathematics • “A phylogenetically old ‘number sense’ system, found in animals and infants as well as older participants, seems to underpin knowledge about numbers and their relations” (Goswami, p. 8). • This system is bilateral in intraparietal areas. • Some aspects of number knowledge stored verbally. • Complex calculations seem to involve visuospatial regions

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42. Learning • Associations? • Behaviorist? • Information processing? • Constructivist?

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44. Brain & Education • A bridge too far? • Critical periods • Modularity • Increase in synapses from infancy to late childhood • Enriched environments cause new synapses to form • Right brain versus left brain (or male versus female brains)

45. Sensitive periods • Hubel & Weisel is often cited. What did they study? • Experience-expectant brain plasticity does not depend on specific experiences in specific environments. Just normal experience. • Not critical periods, but windows of opportunity.

46. Synaptogenesis/Plasticity • Most research done on cats and monkeys. • We create new synapses over the course of a lifetime. • And we also develop new neurons as well (interesting in particular given that this is a relatively recent finding). • Says that we learn, not how we learn. • Complex environments may link plasticity and synaptic changes. Elvis is as good as Mozart

47. Gender-related differences From Kimura in Mind and Brain

48. Gender-related differences From Kimura in Mind and Brain

49. Gender-related differences • No overall differences in IQ of males and females. • Females are favored for verbal ability. • Males seem to be superior to females in visual-spatial tasks, field independence, and quantitative skills. • However, males tend to be more variable in those characteristics than females are. • Overall, the list of difference is short – cognitive similarities are more prevalent than differences.

50. Gender related differences • Brain is not different – these are cognitive preferences (Goswami, 2004). • Yet, how could gender differences be due to biological differences (Pressley & McCormick)? • Males have more lateralized brains with verbal skills more in the left hemisphere. Females have verbal skills more distributed. This could also mean, then, that females have less right brain capacity for spatial processing. Consistent with this theory is that left handed males have less spatial ability. • Within hemisphere differences in the organization of males and females. Females areas of processing are more focused, males more diffuse.