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

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– 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

– 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 cognitionIt is much more then just activation of cortical areas

Adolphs Fig. 1 NATURE REVIEWS | NEUROSCIENCE VOLUME 4 | MARCH 2003 |

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

Adolphs Fig. 2 NATURE REVIEWS | NEUROSCIENCE VOLUME 4 | MARCH 2003 |

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

Adolphs Fig. 5 NATURE REVIEWS | NEUROSCIENCE VOLUME 4 | MARCH 2003 |

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