Reading Skills Are Difficult to Acquire
and Frequently Impaired
Dyslexia—a reading disorder attributed to brain impairment
Classification of Dyslexia
• Acquired (Trauma dyslexia) “alexia” if caused by brain trauma
– Deep dyslexia: problems with whole word recognition related in meaning, cow
for horse
– Surface dyslexia: difficult to recognize words in which the letter-to-sound rules
are irregular.
– Surface dyslexia doesn’t occur in native speakers of languages that are perfectly
phonetic (such as Italian)
• Developmental
– Occurs in 5% of children
– More common in boys and left-handed children
– Primary if from genetic abnormalities
• Genetics related to brain development
– Secondary if from abnormal “slow” development of reading
• hormonal or environmental including neglect.
Developmental Dyslexia
• Not from low intelligence
• Not a visual problem such as letter reversal
• “an unexpected difficulty learning to read despite
intelligence, motivation and education.” (Dyslexia by Sally E.
Shaywitz, Scientific American, November 1996, page 99)
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take longer to learn how to talk
language area of the brain is slower to develop
motor control skills come easier
learn how to walk earlier than other children
higher rate of depression and suicide
less likely to finish high school or college
Developmental Dyslexia
• Disorganized circuits
– Mostly in the temporal lobes
– Some amount in frontal cortex
• Genetic predisposition related to neuronal migration
early in development which produces
– micropolygyria
– ectopias
– dysplasias
• Processing deficits appear as early as 6 months
• Difficulties processing consonant duration
• Disorganized cortical connections
– Disrupts flow of information to the inferior temporal region
Reading Skills Are Difficult to Acquire and
Frequently Impaired
• fMRI indicates differences in brain activity in dyslexia.
• Compared with control subjects, people with dyslexia show diminished
activation of left posterior regions including the superior temporal lobe and
angular gyrus.
• Brains of dyslexics show unusual arrangements of cortical cells.
• Micropolygyria—small regions of excessive number of gyri or cortical
foldings
• Ectopias—clusters of extra cells
• Brain imaging has revealed subtle changes in the fine structure of
the temporoparietal white matter pathways in adult dyslexics,
suggesting problems with the axonal connections between
language-related cortical areas
Neural Disorganization in Dyslexia
Developmental Dyslexia Treatment
• Treated through education, and the sooner intervention begins, the
better.
– Learn to recognize the smallest sounds that make up words (phonemes)
– Understand that letters and strings of letters represent these sounds
• An increase in left-temporo-parietal and left inferior frontal
activity after training
• Also increased activity in right side frontal, temporal and anterior
cingulate gyrus
• Magnitude of increased activation in left temporo-parietal cortex
correlated to improvement in oral language and improved reading
Hemispheric Specialization
• Lateralization means the cerebral hemispheres are specialized
for different functions.
• Hemispheres are strongly connected, masking some features of
specialization.
• Split-brain individuals have disconnected hemispheres.
• Lateralization is widespread among all vertebrates
– Activity of the right hemisphere
• response to novelty
• expression of intense emotions, such as aggression, escape behavior, and fear
– Activity of the left hemisphere
• involves use of learned templates or rules
• categorizes stimuli and responds to features that are invariant and repeated
• process species-typical vocalizations in some mammals and birds
Testing a Split-Brain Individual
Proposed Cognitive Modes of the Two Cerebral
Hemispheres in Humans
Hemispheric Specialization
• Handedness is differential use of the limbs
– This did not originate in humans because other primates also show right
hand preference
– More elaborated in humans because of use of hands
• Handedness correlates with language lateralization
– Left-handed people make up about 10-15% of the population.
– Powerful throwing, as in hunting usually involved the right hand.
– Left-hemisphere circuits for motor control
• Specialized for throwing
• Changed into circuits to control language.
– In 95% of right handers the left hemisphere is dominant for speech
– In 70% of left handers the left hemisphere is dominant for speech
• 15 % are right dominant
• 15% have no dominant side
Structural Asymmetry of the Human Planum Temporale
Social Cognition
• An approach that has its roots in Social Psychology and borrows
heavily from Cognitive Psychology procedures and theory
• Studies how individuals process social information
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Person perception
Attribution
Attitudes
Prejudice and Stereotyping
Judgment of others behavior
Memory of social stimuli
• Studies effects of social and affective factors on information
processing
• Not just cognitive psychology in a social context because
“people are not things”
Evolution of Social Cognition
• Dogs but not other canines
– Track body movements
– Track eye gaze
– Follow pointing gestures
• Non human primates
– Non verbal communication
– Cooperation in small social groups
– Transmission of Culture within the group
• Evolution of large brains in primates
– computational demands of living in large, complex societies
– particular demands of the more intense forms of pair bonding
• Role of language
– Gossip is the most important use of language
Social Cognitive Neuroscience
• Frontal lobes injury can adversely affect social judgments
– Example of Phineas Gage
– Many other examples from Neurology
• Psychological processes that promote social behavior
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Non-verbal communication
Verbal communication
Face recognition
Body shape preferences
Moral judgment and Fair play
Cooperation
Keeping track of social relationships
Mind Reading “theory of mind”
• Specialized circuits for social cognition?
– are cognitive processes for perception, language, memory and attention sufficient to
explain social competence?
– are there specific processes that are special to social interaction?
Social Cognitive Neuroscience
• Brain Imaging has shown important relationships between social
cognitive function and brain regions
– Perception of other human bodies activates posterior temporal cortex, the
extrastriate body area
– Interpreting the motions of a human body in terms of goals involves the
posterior superior temporal sulcus
– Thinking about the mental states of others involves the temporo-parietal
junction
– Emotional empathy in ventral medial prefrontal cortex
– Representation of triadic relations between two minds and an object
supporting shared attention and collaborative goals in dorsal medial
prefrontal cortex
Processes and brain structures that are involved in social cognition
It is much more then just activation of cortical areas
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Empathy as an example
• Empathy is the capacity to recognize feelings that are being
experienced by another
– Has evolutionary, neurological, and biochemical underpinnings
– Related to other aspects of social behavior such as
• social attachment, parental care, and motivation to help
– Part of affective communication
• bottom-up affective arousal
• emotional understanding
• top-down emotion regulation
– Processed in many brain circuits including
• orbitofrontal cortex
• limbic system: amygdala, insula, anterior cingulate cortex,
• hypothalamicpituitary-adrenal axis with autonomic nervous system and
endocrine output such as oxytocin
Figure 1. Empathy is implemented by a complex network of distributed, often
recursively connected, interacting neural regions, as well as autonomic and
neuroendocrine processes implicated in social behaviors and emotional states.
Cacioppo & Decety (2011)
Perception of social signals
• Social visual signals
• Perception of faces
– Facial Expressions
– Eye movement; direction of gaze
– Mouth movement
• Body posture
• Body movement
• Fusiform Face Area for static properties of faces used as indicators
of personal identity
• Superior temporal gyrus and sulcus for processing changes in
– facial expressions
– eye movement
– mouth movements
Visual stimuli for investigating social cognition
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Perception of Human Movement
Blake Annu. Rev. Psychol. 2007. 58:47–73
Thinking about other people
• Theory of mind “mentalizing”
– attribute mental states to other people
– representing what might be going on in other people’s minds
– emerge at about four years of age and may be unique to humans
• Ability to see the world from another’s perspective
– tracking eye-movement and using their visual perspective
– posterior end of the superior temporal sulcus (pSTS) and the adjacent
temporo-parietal junction (TPJ)
• Thinking about mental states
– activates medial prefrontal cortex and adjacent paracingulate cortex
– anticipating what a person is going to think and feel
– predict what they are going to do
• based on past experience of interacting with others
• based on personal experience in similar situations
Investigating theory of mind
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Social reasoning, decision making and dilemmas
• Damage to orbitofrontal cortex impairs
– ability to figure out that other people are being deceptive
– performance in reasoning about social exchange using the Wason
Selection Task
• Damage to the ventromedial prefrontal cortices impairs
– ability to decide when making a risky choice in gambling
– relies on Somantic Markers (Emotional states)
• Moral dilemmas such as the “trolley dilemma”
– Activates Superior Temporal Sulcus, and the cingulate and medial
prefrontal cortices
– Social cooperation engages a similar set of structures
Trolley Dilemma Example
Version one: pulling the switch will
kill one person but save five others
Version two: Pushing the man off the bridge
will kill one person but save five others
Trolley Dilemma Example
Brain Scan studies
–When people contemplate footbridge-type cases
–negative automatic emotional responses to prototypically harmful actions
(pushing someone off the bridge) produces increased activity of the amygdala
–decisions favoring the best outcome (save 5 lives) increase activity in the
ventromedial prefrontal cortex
–Integrative decision making based on activity between amygdala - VMPC
–When people contemplate switch-type cases
–elicit increased activity in the dorsolateral prefrontal cortex, a part of the brain
associated with calculation and reasoning.