wk10 social, emotional and communicative brain II

Overview of Emotions

  • Emotions are valenced responses to stimuli and/or internal representations.

  • Key components: experiential (feeling), behavioral response, physiological.

  • Distinguishable from moods, which are more diffuse and longer-lasting (often have trigger)

  • Depend on different neural systems

  • can be unlearned responses to stimuli with intrinsic affective properties or learned

  • Involves multiple appraisal processes

Categorization of Emotions

  • Emotions can be basic (e.g., anger, fear) or complex (e.g., jealousy, love).

  • The dimensional theory differentiates between valence (positive/negative) and arousal (strength of response).

  • Emotions are often assessed through facial expressions in research.

Key Theories of Emotion Generation

  • James-Lange Theory: Emotions arise from bodily responses to stimuli (e.g., seeing a bear increases heart rate -> feeling fear).

  • Cannon-Bard Theory: Emotion and bodily response occur simultaneously through separate pathways (thalamus to hypothalamus for response, thalamus to cerebral cortex for feeling).

  • Criticised the James-Lange theory

  • experimented with animals by disconnecting their cortex from the brainstem

  • proposed the diencephalic theory of emotion 

  • the diencephalic is made up of the thalamus and hypothalamus

Neuroanatomy of Emotion

  • Important structures in the limbic system include:

    • Thalamus

    • Hypothalamus

    • Amygdala

    • Hippocampus

    • Orbitofrontal cortex

    • Cingulate gyrus

  • 17th century: Thomas Willis noted brainstem encircled by a cortical boarder (cerebri limbus)

  • 19th century: Paul Broca renamed it the grand lobe limbique (limbic lobe)
    Involving cingulate gyrus, hypothalamus, anterior thalamic nuclei and hippocampus

  • 1930s: James Papez suggested this system is responsible for emotional behaviour - coined it the papez circuit
    - Sensory messages regarding an emotional stimulus are directed from the thalamus to the cortex (stream of thinking) and hypothalamus (stream of feeling).
    - Emotional integration occurs through the cingulate cortex

  • 1950s: Paul MacLean named it the limbic system and extended brain areas included (amygdala, orbitofrontal cortex and parts of the basal ganglia)

Critiques of Limbic System Theory

  • Lack of functional and anotomoical coherence in the limbic system.

  • Some structures (e.g., hippocampus) associated more with cognitive processing.

  • Questioning the idea of a single system responsible for all emotional processing.

Role of the Amygdala

  • Amygdala is located in the medial temporal lobe adjacent to the anterior portion of the hippocampus

  • Key for fear processing; extensively connected in the brain.

  • Case studies (e.g., patient SM) show amygdala damage correlates with impaired fear responses.

  • Fear conditioning involves the amygdala linking stimuli to fear responses (e.g., light paired with shock).

Two Pathways to the Amygdala

  • Low Road: Fast, unfiltered sensory information from thalamus to amygdala (15 ms).

  • High Road: Slower, processed information from thalamus to sensory cortex to amygdala (300 ms).

Contemporary Understanding

  • contemporary approaches focus on neural circuits rather than discrete brain regions.

  • Prefrontal cortex involved in reward processing (orbitofrontal) and interpreting bodily signals.

  • Anterior cingulate cortex integrates various information types related to emotional experience.

  • Hypothalamus affects motivations such as sex and hunger (part of a more extensive reward network with PFC, amygdala and ventral striatum)

Neural Reference Space for Emotions

  • Research shows extensive brain networks activated across various emotions, not localised to specific regions.

  • Activation patterns suggest a generalised emotional (superordinate category emotion) processing involving multiple structures.

Conclusion

  • Emotions are complex, comprising physiological, behavioral, and feeling components.

  • Limbic system is central, but broader networks are involved in emotional processing.

  • Current theories emphasise dynamic interactions among neural circuits for emotional experience.

  • Cognitive neuroscience has identified a number of anatomical regions involved in emotion processing

• limbic system (hypothalamus, thalamus, hippocampus, amygdala, orbitofrontal cortex, cingulate gyrus, basal ganglia)

• amygdala: important for processing / experiencing fear; fear conditioning

• “generalised emotional brain” also includes other regions (e.g. PFC); cf. “neural reference space for emotions” – brain regions consistently activated across a range of emotions

Additional / Text book

  • The locationist account of emotion suggests that mental states belonging to the same emotion category are produced by specific neural circuits that, when activated produce specific behaviour

  • basic emotions are carved by evolution and reflected through facial expressions

  • complex emotions are combinations of basic, some of which may be socially or culturally learned (evolved)

  • dimensional theories of emotion describe emotions as fundamentally the same but differ alone one or more dimensions such as valence and arousal

  • Valence = pleasant-unpleasant

  • Arousal = intensity of the internal emotional response, high or low

  • Singer and Schachter emotion theory posits that cognitive appraisal of stimulus occurs then behavioural and emotional response

  • LeDoux emotion theory posits that emotions are processed in the brain through two pathways: the fast, automatic pathway that bypasses conscious thought, and the slower, more deliberate pathway that involves cognitive appraisal.

  • Cosmides and Tooby emotion theory posits that emotions are a coordination of automatic processes including physiology, behavioural inclinations, cognitive appraisals and feel states

    Panksepp’s Hierarchical-processing theory of emotion posits emotions are processed in three ways:

    • Primary process (core emotion): Arises from subcortical neural networks, requiring no cognitive appraisal.

    • Secondary process: Shaped by cognitive appraisal and social context.

    • Tertiary process: Emerges from complex interactions between primary and secondary processes, reflecting higher-level interpretations and social learning.

  • Anderson and Adolphs argue an emotional stimulus activates a CNS state that simultaneously activates multiple systems producing separate responses

  • The amygdala is the most connected structure in the forebrain

  • The amygdala contains receptors for many difference neurotransmitters and for various hormones 

  • Damage to the amygdala impairs conditioned fear responses

  • Emotional learning can be both implicit and explicit; the amygdala is necessary for implicit emotional learning while the hippocampus plays a crucial role in explicit emotional memories.

  • Conscious knowledge cannot generate physiological changes associated with fear if there is no link to the amygdala and it’s midbrain connections

  • The hippocampus is necessary for the acquisition of a memory, but if the arousal accompanies memory acquisition, the strength and duration of that memory is modulated by amygdala activity

Neuroanatomy of Emotion

  • In the Papez circuit, the cingulate gyrus:

    • Integrates various sources of emotional information (e.g., sensory messages from the thalamus and feelings from the hypothalamus).

    • Provides output for cognitive appraisal, contributing to a top-down modulation of emotional responses.

Neural Reference Space for Emotions

  • Refers to a set of brain regions consistently activated across a range of different emotions.

  • Implies extensive brain networks are involved in a generalized emotional processing, rather than emotions being localized to specific, individual regions.