Insula Flashcards
The insula is involved in…
- representation of bodily changes (connections with ACC);
- empathy (connections with ACC);
- decision-making in complex situations (somatic marker) (connections with PFC and ACC);
- disgust processing
Activity in bilateral insula is enhanced when…
attending to heartbeat timing relative to an exteroceptive “note” task
Right anterior insula activity
Activity in right anterior insula correlates with interoceptive sensitivity (performance accuracy
on the task) and day-to-day experience of anxiety → the right anterior insula may be
a substrate for feeling states generated from afferent visceral responses
Which afferents does the insula recieve?
The insula receives topographically organized afferents from distinct thalamic relay nuclei and integrates information about blood pressure and oxygenation, the motility of the digestive system, the timing and strength of the heartbeat, as well as pain, hunger, nausea, tickle, itch and many more bodily sensations
Insula and interoception
The insula contains topographic interoceptive or viscero-sensory maps, that represent vestibular,
nociceptive, thermoreceptive, visceral and gustatory information.
The different roles of anterior and posterior insula
Interoceptive information of constantly changing body states arrives in the posterior (granular) insula by ascending sensory inputs from dedicated spinal and brainstem pathways via specific thalamic relays. This information is projected rostrally onto the anterior (agranular) insula, where it is integrated with emotional, cognitive, and motivational signals from an array of cortical and subcortical regions; as a result, the anterior insula supports unique subjective feeling states
Insula-cortical connections
- ventral anterior insula —> amygdala, hippocampus, anterior cingulate, MOFC, MAPFC
- dorsal anterior insula —> STG, Broca’s area, DLPFC
- posterior insula —>somatosensory cortex, precuneus, SMG angular gyrus, SMA motor cortex
Insula’s cytoarchitecture differentiation
Insula subregions are cytoarchitecturally differentiated based on relative presence or absence of various neuron types.
Granular layer IV neurons and von Economo neurons (VENs) have gradated prevalence along an anterior-to-posterior axis within the insula, but with opposite trends (VENs more anterior less posterior, granular layer IV neurons more posterior less anterior)
While cortical granular layer IV neurons are implicated in processing of sensory inputs from the thalamus, VENs have been associated with higher-order cognitive functioning, including empathy, social awareness, and complex emotional processing
This integration of neuronal cell types in the insular cortex may underlie its varied functions in emotion and cognition (in the anterior portions) and somatosensation (in the posterior portions)
What are the granular neurons?
Granular cortex is characterized by six differentiated laminae (layers I–VI), with layer IV containing granule cells, which are excitatory spiny stellate neurons that amplify and distribute thalamocortical inputs throughout the column
What are the Von Economo neurons?
Von Economo neurons, also called Spindle neurons, are characterized by a large spindle-shaped (thin, elongated) cell body, one large apical axon and a single basal dendrite. Whereas other types of neurons tend to have many dendrites, the polar shaped morphology of spindle neurons is unique. With their large diameter axons, VENs facilitate rapid long-range information transfer
VENs are found in layer 5 of anterior cingulate and fronto-insular cortex
VENs develop late, both ontogenetically and phylogenetically.
VENs first appear in the 35th week of gestation; at four years old, the adult numbers are present
VENs across species
VENs are only found in primates, a few large mammals such as elephants and hippopotamuses, and cetaceans. Among primates, VENs have only been found in the great apes, humans, gorillas,
chimpanzees, bonobos, and orangutans.
Humans have the most VENs, both in terms of absolute number and relative percentage compared to total number of neurons
VENs social role
VENs possibly contribute to specializations of neural circuits in species that share both large brain size and complex social cognition.
Due to the relative lack of granule cells and the relative abundance of VENs that connect frontoinsular regions with frontal and temporal cortices, it is plausible to hypothesize that
the anterior insula is predisposed to higher-order socio-cognitive and socio-emotional processing in humans (e.g., self-awareness, ToM, intuition, empathy, …)
What’s Empathy?
It is an ‘umbrella’ term for all processes that emerge from the fact that observers understand
others’ states by activating their own personal, neural and mental representations of that state
What’s the difference between affective empathy and cognitive empathy?
a) Affective empathy: directly affected by the emotional state of another by matching or ‘feeling
with’ it, as a result of perceiving this state; an affective response to another person, which often,
but not always, entails sharing that person’s emotional state
b) Cognitive empathy: derived from a top-down process in which the observer imagines how the
target feels, even if the target is not present or their feelings cannot be directly observed; a cognitive capacity to take the perspective of the other person while keeping self and other differentiate
Which are components of empathy?
Various components of the empathic response, which have been added layer upon layer during evolution, remain functionally integrated. From inner to outer:
- Perception–action mechanism: the core, the automatic activation of relevant emotional/motor representations in the mind of an observer when they pay attention to the emotional state of another person, which induces a similar emotional state in the observer as in the target
- Empathic concern and consolation
- Perspective-taking and targeted helping
The last ones build upon the core, while increasingly requiring emotion regulation, self–other distinction and cognition
Empathy and pain
In experimental research, the perception of pain in others has often been investigated as a way to
address the processes involved in empathy
The perception of pain in others can be viewed as a social stimulus that triggers a specific mental
(affective) state in the perceiver from which empathic processing may stem
The insula is more activated when seeing another feeling pain
What’s the analogical understanding in terms of pain?
Despite the patients’ lack of sensory experience of pain, previous experiences of psychological distress might allow them to understand what it means to feel pain (“analogical understanding”)
Empathy for social pain (negative social experiences)
Observing one person being excluded (vs. included) by others activates regions associated with
mentalizing (dmPFC, mPFC) → simply watching someone experiencing social pain may not
automatically elicit distress like observing physical pain
Highly empathic individuals activate both mentalizing regions and pain-related regions (dorsal ACC, anterior insula) →understanding the situation and imagining the victim’s affective responses might only elicit pain-related neural activity among the most empathic individuals
Which areas and parts on insula activate during empathy?
Independent of task and stimulus type, consistent activation of the dACC-aMCC-SMA and the bilateral anterior insula in empathy
The right anterior insula is activated only in affective empathy (sharing the other’s emotional experience), whereas the left anterior insula is activated in both affective and cognitive empathy
(understanding the other’s feelings, or perspective taking)
Insula involvement in disgust
The insula is activated by stimuli that specifically elicit disgust
The insula is activated during disgust in a modality-aspecific way: by observing others’ facial
expressions of disgust, tasting bitter solutions, and imagining oneself feeling gustatory disgust
However, the functional connectivity between this region and the rest of the brain is orchestrated in a modality-specific way (experience/imagination→ SI/SII, posterior insula, basal ganglia, orbitofrontal cortex, cingulate and primary motor cortex; observation→ IFG)
Insula and unfairness
The insula is more activated when receiving an unfair (vs. fair) offer → moral emotion-based disgust induced by the insulting offer.
The bilateral anterior insulae demonstrate sensitivity to the degree of unfairness of the offer.
Right anterior insula (rAI) activation and SCR for all unfair offers, categorized by subsequent acceptance or rejection. Activation of the rAI and SCR amplitude predict the decision to either accept or reject unfair offers→ neural representations of emotional states guide human
decision-making
