1. Brain Asymmetry and Lateralization of function
Lateralization means the cerebral hemispheres are specialized for different functions.
Language
spatial
However, no evidence supports notions that personality traits, creative or analytical thinking are linked to one hemisphere or the other.
Hemispheric specialization may have originated in differential use of limbs.
Powerful throwing, as in hunting, involved the right hemisphere
left-hemisphere circuits needed to program throwing may have begun to control language
Other vertebrates also show preference for one limb or the other, so lateralization may have evolved for processing efficiency.

2. The Left Brain Is Different from the Right Brain
Handedness
Left-handed people make up about 10–15% of the population.
Left-handed children do not differ from right-handed children on any measure of cognitive performance.
Handedness may have a genetic component, but if so, it is not a simple, single gene effect.
One gene that may contribute to handedness is LRRTM1, a gene associated with glutamate neurotransmission that is also implicated in schizophrenia.
Many genes related to handedness some of which regulate body symmetry

3. Figure 19.1 Testing a Split-Brain Individual
Hemispheres communicate with each other so quickly, lateralization of function is masked.
Sperry’s studies tested language function in each hemisphere of split-brain individuals.
Split-brain individuals’ hemispheres are disconnected due to the surgical severing of the corpus callosum to alleviate seizures.
Words presented to either visual field showed language ability only if the information reached the left hemisphere.
Figure 19.1  Testing a Split-Brain Individual Words or pictures projected to the left visual field activate the right visual cortex. (A) In intact individuals, activation of the right visual cortex excites corpus callosum fibers, which transmit verbal information to the left hemisphere, where the information is analyzed and language is produced. (B) In split-brain individuals, stimuli from the left visual field reach the right-hemisphere visual cortex via the subcortical visual pathways (they are independent of the corpus callosum). However, the split corpus callosum prevents right-hemisphere visual areas from communicating with the language areas of the left hemisphere, so verbal responses to the stimuli are impossible (left). In contrast, split-brain individuals are able to respond verbally to stimuli appearing in the right visual fields, because interhemispheric transfer is not required (right).

4. Figure 19.3 The Right-Ear Advantage in Dichotic Presentation
A dichotic presentation delivers different stimuli to each ear at the same time.
Right-handed persons identify verbal stimuli delivered to the right ear more accurately than verbal stimuli delivered to the left—a right ear advantage.
50% of left-handed individuals have a left-ear advantage.
The right ear advantage may reflect the left hemisphere’s specialization for language.
This advantage is only evident in simultaneous presentations and is restricted to consonants.
Figure 19.3  The Right-Ear Advantage in Dichotic Presentation
(A) A word delivered to the left ear results in stronger stimulation of the right auditory cortex. (B) A word delivered to the right ear results in stronger input to the left hemisphere. (C) When words are delivered to both ears simultaneously, the word to the right ear is the one usually perceived because the right ear has more-direct

5. The Left Brain Is Different from the Right Brain
The right hemisphere is specialized for:
Processing emotional tone of language
Prosody: the patterns of stress and intonation in a language
Perception of music
Controlling attention
Spatial processing, including:
Face perception
Geometric shapes and relations
Direction and navigation
3D rotation of imaginary objects

6. Figure 19.5 Use of the Right Hemisphere for Facial Recognition
Anesthetizing the left hemisphere in a Wada test (see Box 19.1) does not interfere with a participant’s ability to recognize her own face in a picture that is a composite of her face and the face of a celebrity. But when the right hemisphere is anesthetized, the participant interprets the composite face as that of the celebrity.
Figure 19.5  Use of the Right Hemisphere for Facial Recognition
Anesthetizing the left hemisphere in a Wada test (see Box 19.1) does not interfere with a participant’s ability to recognize her own face in a picture that is a composite of her face and the face of a celebrity. But when the right hemisphere is anesthetized, the participant interprets the composite face as that of the celebrity. (From Keenan et al., 2001, courtesy of Dr. Julian Keenan.)

7. Right-Hemisphere Damage Impairs Spatial Cognition
Prosopagnosia can result from
brain damage (acquired prosopagnosia)
congenital prosopagnosia—lifelong face blindness not due to brain damage—occurs in about 2.5% of the general population.
Bilateral damage to the fusiform gyrus causes complete prosopagnosia.
located in the Inferior temporal cortex part of the visual ventral stream
Prosopagnosia may be accompanied by other forms of agnosia, an inability to identify items such as different kinds of cars or species of birds.
On the other hand, some people are “super-recognizers.”

8. Reading Skills Are Difficult to Acquire and Frequently Impaired
Dyslexia: A reading disorder attributed to brain impairment.
Acquired dyslexia (alexia) can occur in adults after injury to the left hemisphere.
Deep dyslexia is an acquired dyslexia in which a person reads a word as another semantically related word.
Surface dyslexia, another acquired dylexia, the person attends only to the fine details of reading—which letter makes which sound.
Surface dyslexics find it difficult to recognize words in which the letter-to-sound rules are irregular.
Developmental dyslexia occurs in 5% of the general population.

9. Figure 19.19 Neural Disorganization in Dyslexia (Part 1)
Brains of dyslexics show unusual arrangements of cortical cells.
Micropolygyria - small regions of excessive number of gyri or cortical foldings
Ectopias - clusters of cells in unusual places
Dysplasia - loss of characteristic architectural organization of the cortical neurons, mainly subjacent to the site of ectopias
Figure 19.19  Neural Disorganization in Dyslexia (A) (Top) Drawings of the left and right planum temporale (see Figure 19.4) from the brain of a person with dyslexia show these regions as nearly symmetrical; in most people the left planum temporale is considerably larger. The dots and the shaded area represent regions where microscopic anomalies called ectopias, dysplasias, and micropolygyria have been found in the brains of individuals with dyslexia. (Bottom) Anomalies in individuals with dyslexia are much more common in the left hemisphere, which is primarily responsible for language function. (B, C) These micrographs show (B) micropolygyria (literally “many tiny gyri”) and (C) ectopias, clusters of neurons in unusual locations, such as this cluster in cortical layer I (arrow), which is normally devoid of neuronal cell bodies. (After Galaburda, 1994; micrographs courtesy of Dr. Albert Galaburda.)

10. Social Cognitive Neuroscience
An approach that has its roots in Social Psychology and borrows heavily from Cognitive Psychology procedures and theory
A combination of social paradigms, cognitive tasks and neuroimaging
Studies how individuals process social information
Person perception – how you perceive individuals and
Attribution – nice person bad person
Attitudes – likes and dislikes
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”

11. 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 in humans
Gossip is the most important use of language

12. 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
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 cognitive processes that are special to social interaction?

13. Social Networks In The Brain
social networks of friends and family
understanding the social relationships allows us to interact with them appropriately
to maintain social networks requires keeping track of our relationships to others and some understanding of their relationships to one another
fMRI studies of participants while they viewed film clips of individuals within this social network
their friends, some were friends of their friends and some were friends of their friends’ friends (two vs. three degrees distant)
distributed network of brain regions was sensitive to the social status
familiarity and social distance are processed in the inferior parietal lobule
socially relevance of other people is processed in the medial prefrontal

14. 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