How does brain activity during body awareness relate to alexithymia?

What is alexithymia and what is its literal meaning?

Alexithymia is a multifaceted personality construct characterized by individuals having difficulties identifying or describing feelings, literally translating to "no words for feelings."

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What is the most commonly used self-report measurement for alexithymia?

The most widely used self-report assessment is the 20-item Toronto Alexithymia Scale (TAS-20).

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What are the three subscales of the Toronto Alexithymia Scale (TAS-20)?

The subscales are difficulties identifying feelings (DI), difficulties describing feelings (DD), and externally oriented thinking (EO).

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How is interoceptive awareness (IA) defined in the context of neuroimaging and emotional processing?

Interoceptive awareness (IA) is the awareness of stimuli that originate within the body, such as the heartbeat.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What neural abnormality during IA has previous neuroimaging research consistently identified in MDD?

Previous research has shown aberrant neural activity during IA in Major Depressive Disorder (MDD), specifically presenting as decreased activity in the insula.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What regional cerebral blood flow pattern did visual emotional processing PET studies reveal in the insula of healthy, highly alexithymic individuals?

Highly alexithymic individuals demonstrated increased regional cerebral blood flow in the insula compared to low alexithymic controls during visual emotional processing.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What pattern of anterior cingulate cortex (ACC) activation was reported when comparing high versus low alexithymic individuals during emotional processing in PET studies?

High-alexithymic individuals showed less activation in the anterior cingulate cortex compared to low-alexithymic individuals.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

Neurally, what is thought to underlie the subjective somatic hyperawareness reported by individuals with alexithymia?

Subjective somatic hyperawareness is linked to increased neural activity in the insula, particularly in response to bodily and somatosensory stimuli.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI

What did magnetic resonance spectroscopy (MRS) show regarding glutamate levels in the insula of alexithymic individuals?

Insular glutamate levels were positively associated with alexithymia and body awareness, suggesting elevated excitatory transmission in this region.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

According to MRS studies, what biochemical finding in the ACC is linked to decreased neural activation in alexithymia?

Levels of GABA, the primary inhibitory neurotransmitter, were positively associated with alexithymia in the ACC, possibly explaining decreased neural activity.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What medial prefrontal cortex activity pattern during IA did the authors hypothesize for healthy alexithymic individuals?

They hypothesized that healthy individuals with high alexithymic traits would display reduced neural activity in medial prefrontal regions, such as the ACC, during IA.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI

What contrasting insular activity patterns did the authors hypothesize for healthy alexithymic individuals versus depressed alexithymic individuals during IA?

They hypothesized that healthy alexithymic individuals would show increased insula activity, while the depressed alexithymic group would show reduced insula activity.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How many participants from each group (NC and MDD) were ultimately included in the study's final analysis?

The final analysis included 30 non-psychiatric controls (NC) and 16 major depressive disorder (MDD) patients.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

Why were six MDD patients excluded from the primary statistical analyses?

Six patients with major depressive disorder had missing Toronto Alexithymia Scale (TAS) scores.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What did the Exteroceptive Awareness (EA) task condition require participants to do?

During the EA condition, participants were instructed to focus on and silently count the number of externally presented auditory tones.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How did the researchers equate the perceived difficulty of the heartbeat counting and tone counting tasks?

Participants adjusted the volume of the auditory tones during dummy scans until the task difficulty matched that of heartbeat counting.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How did the researchers ensure the frequency of auditory tones did not act as a confounding factor relative to physiological rate?

They customized the presentation frequency of the auditory tones to match each individual's recorded heart rate.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

Why did the researchers introduce a 200 ms jitter to the onset of the auditory tones?

The tone onset was jittered by 200 ms to prevent habituation effects during the exteroceptive awareness task.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What did the baseline condition of the fMRI paradigm consist of and how was it signaled?

The baseline condition consisted of undirected awareness (no active counting task) and was signaled by a dark visual cross.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What advanced ICA method was used to denoise the functional neuroimaging dataset?

Probabilistic Independent Component Analysis (PICA) via FSL-MELODIC was utilized, and noise components were manually identified and regressed out.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How was the continuous TAS-DD scale converted into a categorical variable for subgroup analysis in the NC group?

The NC group was divided into high and low alexithymia subgroups using a median-split of their TAS-DD scores.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How did the TAS-DD scores of the high-alexithymic healthy controls compare to the MDD group?

The high-alexithymic controls and the MDD group had equally high alexithymia scores, allowing for a matched comparison.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What differences in slope were found between healthy controls and MDD patients when relating IA-related activation to TAS-DD scores?

Healthy controls showed a negative correlation in medial-frontal regions between IA-related activity and TAS-DD, while MDD patients showed no such correlation.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What major variables yielded significant group differences in the overall MANOVA of healthy and depressed participants?

The MANOVA revealed significant group differences for all three TAS subscales and BOLD responses during IA in all three functional ROIs.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

Did exteroceptive neural activity or gray matter volume within the target ROIs demonstrate significant differences between the three participant groups?

No, there were no significant group effects detected for EA-related BOLD responses or gray matter volumes within the ROIs.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What regional spatial gradient was discovered when evaluating IA-related BOLD signals across all participants?

The BOLD response followed a dorsal-to-ventral gradient: positive signals in the most dorsal region, reduced activity in the sACC, and negative signals in the most ventral region.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI

How did sACC activity differ between low-alexithymic and high-alexithymic healthy controls during IA?

Low-alexithymic controls showed increased IA-related sACC activity compared to high-alexithymic controls, who showed negative BOLD responses (deactivation).

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What insular activity difference was observed when comparing high-alexithymic healthy controls directly with low-alexithymic controls?

Healthy controls with high alexithymia scores showed significantly increased neural activity in the left insula during IA compared to those with low scores.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What primary insular difference was identified when comparing high-alexithymic healthy controls directly with MDD patients?

High-alexithymic healthy controls showed increased IA-related activity in the bilateral insula compared to MDD patients, who showed low neural activity.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

Did sACC activation during IA differ between high-alexithymic healthy controls and MDD patients?

No, both groups demonstrated comparable negative BOLD responses (deactivations) in the sACC, showing no significant differences.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI

What differences were revealed on a whole-brain level when comparing the two most distinct groups: low-alexithymic controls and MDD patients?

Low-alexithymic controls showed significantly greater neural activity during IA in both the bilateral insula and the sACC compared to MDD patients.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What compensatory mechanism within the salience network is proposed to occur in healthy individuals with high alexithymia?

Upregulated insula activity is thought to compensate for decreased sACC activity, ensuring sufficient processing of body-related interoceptive signals.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

Why is the proposed insula-sACC compensatory mechanism thought to be disrupted in Major Depressive Disorder?

Because depressed patients show the same decreased sACC activity but fail to show the compensatory increase in insular activity seen in healthy alexithymics.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

What major patient-related limitation did the authors note regarding the MDD cohort?

The patients with MDD were under medication, meaning potential medication effects on functional activity cannot be fully ruled out.

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified

How did this study differentiate between interoceptive accuracy and interoceptive awareness?

This study focused on the cognitive act of directing awareness to internal states (interoceptive awareness) independent of task performance or behavioral tracking accuracy (interoceptive accuracy).

Source: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls · DOI · quote verified