Neuroscienze sociali appunti per esame - Candidi

Social neuroscience

Chapter 2: The methods of social neuroscience

Temporal resolution refers to the accuracy with which one can measure when an event is occurring. Spatial resolution refers to the accuracy with which one can measure where an event is occurring. Invasiveness concerns whether the equipment is located internally or externally (e.g., PET).

Three different ways of measuring behaviour and cognition

• Performance-based measures: The dependent measures are typically response times or error rates.
  • Advantages: They reflect actual behavior and are simple to analyze.
  • Disadvantages: They are hard to link directly to neural substrates.
• Observation-based measures: The dependent measure is often a frequency count of how often something occurs, such as preferential looking paradigms and habituation paradigms.
  • Advantages: Used when it is impossible or inappropriate to give instructions, and are set in naturalistic settings.
  • Disadvantages: Difficulties associated with scoring and observed biases.
• First-person based measures: The dependent measure may be scores on a questionnaire.
  • Advantages: They can be used in situations where experimental manipulation is not possible.
  • Disadvantages: Participants’ self-reports may not reflect their true behavior.

Measuring bodily responses

• The skin conductance response (SCR): Measures increased activity of the sympathetic system. During a sweating response, there is decreased conductivity of the skin and electrical signals flow more easily. The electrodes are normally placed on two adjacent fingertips with gel to improve contact.
• Electromyography (EMG): An electrical measure of muscle contraction, a method for assessing electrical activity associated with muscle movement.
  • Advantages: Easy to record and analyze.
  • Disadvantages: Not directly linked to brain and cognition.

Electrophysiological methods

These methods measure changes in the responsiveness of a neuron to changes in a stimulus or in a task.

• Single cell recording: Involves implanting a very small electrode into the axon; it is invasive.
• Electroencephalography (EEG): Post-synaptic dendritic recording of electrical signals generated by the brain, through electrodes placed at different points on the scalp; it is non-invasive. It captures rhythmic oscillations in the EEG signal and Event-related Potentials (ERPs).
  • Advantages: Excellent temporal resolution.
  • Disadvantages: Poor spatial resolution.
• Magnetoencephalography (MEG): Similar to EEG but with better spatial resolution in addition to excellent temporal resolution.

Functional imaging: Hemodynamic measures

These measures record blood flow or blood oxygenation (e.g., PET, fMRI). The BOLD response (Blood oxygen level dependent) includes initial dip, overcompensation, and undershoot. Voxel analysis of FMRI data: Determines whether there is a statistically significant relationship between the changes in BOLD signal over time based on what is expected from the study design.

Pre-processing

• Link brain images to the timing of the stimulus presentation.
• Correction for head movement.
• Stereotactic normalization (maps voxels on an individual's brain onto the equivalent region in a standard brain).
• Smoothing (increasing the spatial extent of activity in voxels).

Functional connectivity vs effective connectivity

Lesion methods and brain stimulation

• Experimentally induced lesion in animal models: Methods include aspiration, transection, neurochemical lesions (toxins), and reversible lesion (pharmacological manipulations).
• Transcranial magnetic stimulation (TMS): The TMS coil is held against the patient's head and a localized magnetic field is generated during task performance.
  • Advantages: Investigates timing and location of cognition.
  • Disadvantages: Can only stimulate certain regions, not distant sites.
• Transcranial direct current stimulation (tDCS): Uses a very weak electric current applied between two electrodes during a task.
  • Disadvantages: Low spatial and temporal resolution.

Measuring biological individual differences

• Genetic differences (genotype-first and phenotype-first).
• Neuroendocrine differences (hormones like cortisol, testosterone, oxytocin, and vasopressin).

Chapter 3: Evolutionary origins of social intelligence and culture

Social intelligence refers to the ability to understand and predict complex social interactions. Humans excel in the social domain through tasks such as social learning, communication, and gaze following. Culture is the shared set of values, skills, artifacts, and beliefs among a group of individuals. Social learning involves the transmission of skills and knowledge from person to person.

The social intelligence hypothesis (or social brain hypothesis)

Evolutionary pressures to be socially smarter lead to more general changes, resulting in increased intellect in non-social domains. Schaik considered three different interpretations of this basic idea:

• Intelligence is manifested in social life.
• Complex society selects for enhanced intelligence.
• Complex society selects the specific characteristics of intelligence.

Social intelligence and brain size in primates

There is a strong correlation between social intelligence and brain size. The larger the brain, the greater number of social relationships that can be sustained. Maintaining an insect social group does not require the same cognitive mechanisms found in primates and humans, nor do they require the largest brains.

Correlation between frequency and tactical deception.

Social intelligence and brain size in non-primates

Convergent evolution: The same evolutionary selection pressures create the same outcome independently in different species, such as dolphins, elephants, hyenas, and bats.

Language evolution and the social intelligence hypothesis

Whether language arose from non-specific evolutionary changes such as brain size. Gould and Chomsky think that language arose out of general selection pressures to be smarter.

Evolutionary origins of culture

• Meme and traditions: Culture.
• Culture in non-human species involves methods like how to get food.

Culture pyramid: social information transfer, traditions, culture equals cumulative culture.

Social learning vs imitation

Not all species have the same mechanism of social learning. Humans have one unique technique: they can acquire via language. Only humans are capable of imitation.

• Copying the action without understanding the goal of the action.
• Stimulus enhancement or local enhancement.
• Contagion.

Experiment: Infants watched an adult press the button using the forehead.

Intentional stance

Material symbols: neuronal recycling and extended cognition

Letters and numbers.

Cultural skills: tools and technology

Modifying the brain by using tools and technology. As a result of using tools, the receptive field was no longer centered on the arm but was elongated down the length of the tool itself.

Mirror neurons, action understanding, and imitation

Mirror neurons respond if an appropriate action is implied as well as directly observed. Broca’s area.

Why monkeys do not use tools

Monkeys who are tool-users have extra connections between the intraparietal sulcus and the temporo-parietal junction.

Chapter 4: Emotions and motivation

Some characteristics of emotions

• A state associated with stimuli that are rewarding or punishing.
• Transient.
• Have a hedonic value: they are subjectively liked or disliked.
• Have a particular feeling state in terms of an internal bodily response.
• Emotions elicit particular external motor outcomes in face and body (expression).

Theory of motivation (Rolls)

Historical perspective on the emotions

1. Darwin’s evolutionary theory of emotion: 1872 The expression of the emotions in man and animals. Similarities between facial expressions of humans and non-humans in particular emotions. How many expressions are conserved across species? They are innate.
2. Freud and unconscious emotional motivations: Emotions are an unconscious bias in our behavior.
3. The James-Lange theory: The self-perception of bodily changes produces emotional experience (one is sad because one cries).
4. The Cannon-Bard theory: Based on the hypothalamus’s role in emotions, bodily responses occur after the emotion itself.
5. The Papez circuit and the limbic brain: Papez argued that the feeling of emotions originated in the subcortical Papez circuit, a limbic-based circuit once thought to constitute a largely undifferentiated emotional brain. A second circuit, involving the cortex, amygdala, and orbitofrontal cortex, is called the limbic brain.
6. Ekman and basic emotions: Ekman identified six basic emotions: happy, sad, disgust, anger, fear, and surprise. Each emotion has its specific natural basis, evolved to deal with different survival problems, and occurs automatically.
7. Plutchik: Eight basic emotions: surprise, sadness, disgust, anger, anticipation, joy, acceptance, fear.
8. Rolls: Different types of emotion emerge from consideration of a small set of principles including whether a reward or punishment is applied, the intensity of the above, different combinations of the above, and the context in which an emotional stimulus appears.
9. The theory of Barrett and colleagues: Emotions tap into a system termed CORE EFFECT, organized along two dimensions: pleasant-unpleasant and high/low arousal.

The concept of basic emotion rests on the assumption that there are separate neural foundations for different emotions. Other evidence suggests that both the amygdala and insula are involved in processing other emotions, which is possible if we consider the hypothesis that some emotions are more distributed across the brain than others.

Amygdala and fear

The amygdala is believed to be important for memory, particularly for emotional content of memories. In monkeys, bilateral lesions of the amygdala produce the Kluver-Bucy Syndrome, which includes behaviors of unusual tameness, emotional blunting, a tendency to examine objects with the mouth, and dietary changes. The amygdala is important for both learning and storing the conditioned fear response. The ability to detect threat is so important, evolutionarily, that it may occur rapidly and without conscious awareness; people are faster at detecting fear-related stimuli. In addition, it appears to have a more general role in learning and storing the emotional value of stimuli, which includes both positive and negative associations to stimuli. Amygdala lesions do affect other aspects of reward-based learning, such as second-order conditioning.

The insula and the disgust

The insula is involved in various aspects of bodily perception, including important roles in pain and taste perception. Damasio reported insula activity in response to recalling emotional memories linked to emotions.

Anger

Anger is linked to the ventral striatal region of the basal ganglia. The dopamine system is linked to aggressive behavior in rats.

Motivation: Rewards and punishment, pleasure and pain

• Hierarchy of needs: Physiological, safety, love, esteem, self-actualization.

Innate versus conditioned likes and dislikes: Primary reinforcers act as rewards or punishers without any learning (smells, tastes, facial expressions), while secondary reinforcers act as rewards or punishers as a result of learning.

The orbitofrontal cortex computes the motivational value of rewards

The general function of the OFC is in computing the current value of a stimulus, such as chocolate. This includes the emotion of regret, as observed in tasks like the Iowa gambling task.