Cardiac and gastric interoceptive awareness have distinct neural substrates (Haruki & Ogawa 2023)
Thirty-one people lay in a scanner and were asked, in ten-second blocks, to attend to their heartbeat, to their stomach, or to a word slowly fading from black to grey. That is the whole design. It is the first study to put two interoceptive channels through the same attention paradigm in the same people and compare them directly — and the answer is that the brain does not treat “attending to the body” as one thing.
Why this paper matters more than its size suggests
The wiki arrived at this file immediately after Banellis et al. (2026), which showed that cardiac and respiratory interoceptive performance do not correlate across people. That was a behavioural, individual-differences null. This is the neural, within-subject counterpart: not “your heart score fails to predict your lung score” but “attending to your heart and attending to your stomach are different brain events, in the same head, minutes apart.”
The two results are logically independent — decorrelated individual differences could coexist with a shared substrate, and a shared substrate could coexist with decorrelated scores — and they point the same way. See is-interoception-domain-general.
The finding that costs the wiki something
The right anterior insula is cardiac, not interoceptive-general.
This wiki is built on a claim it inherited from Craig (2009) and has repeated on a dozen pages: the right anterior insular cortex is where bodily state becomes subjective feeling. The evidence for it is overwhelmingly cardiac — heartbeat-detection accuracy correlating with right AIC activation (Critchley et al. 2004; Pollatos et al. 2007; Caseras et al. 2013), a meta-analysis of heart-focused interoception finding right insula the most consistent activation (Schulz 2016).
Haruki & Ogawa put a second organ beside the first and the right AI goes with the heart. It was the only region preferring cardiac to gastric attention. And the authors assemble the corroborating negatives from elsewhere: the accuracy-to-right-AIC correlation does not appear for awareness of breathing (Wang et al. 2019) or of skin conductance (Baltazar et al. 2021).
Their proposed reason is functional rather than anatomical, and it is the best part of the paper’s argument. Cardiac awareness is how a person notices arousal (Paulus et al. 2019). The right insula is where arousal is built: resecting it diminishes physiological and emotional arousal (Terasawa et al. 2021; Holtmann et al. 2022), and false accelerated cardiac feedback both raises perceived arousal (Story & Craske 2008) and activates right AI (Gray et al. 2007; Kleint et al. 2015). So the right AI may look like the seat of interoceptive awareness because the field has been asking it about the one organ that reports arousal. See insular-cortex, false-feedback-paradigm.
A wrinkle that complicates it further, and that the paper reports without dwelling on: right ASG was activated MORE by the visual control task than by interoceptive attention (F(1,30) = 10.28, p = 0.003). The dorsal anterior insula is not straightforwardly an interoceptive region at all — it prefers cardiac within interoception while preferring a demanding exteroceptive task to interoception.
The stomach’s surprise: gastric attention lights up visual cortex
The largest cluster in the study — 3793 voxels, t = 8.42 — is visual cortex, during attention to the stomach. With eyes fixed on a word, no food cue, no gastric stimulation.
The authors’ case that this is real and not artefact rests on convergence:
- The medial visual territory overlaps the resting-state gastric-network (Rebollo et al. 2018; Rebollo & Tallon-Baudry 2022), which is defined by phase-locking to the stomach’s ~0.05 Hz rhythm and which likewise includes occipitotemporal cortex.
- Direct gastric stimulation — electrical or vibratory — evokes occipital activity in rats (Cao et al. 2019), cats (Pigarev et al. 2013) and humans (Mayeli et al. 2021).
Their functional reading: gastric state is for foraging and feeding, which requires integrating visuospatial information with energy status and motor coordination. Consistent with that, gastric attention also recruited left orbitofrontal cortex (most consistently activated region for visual food cues per van der Laan et al. 2011), bilateral posterior hippocampus (see gut-hippocampal-memory), and primary motor cortex.
Take this one more loosely than the insula result. The convergence is genuine but the overlap claim is eyeballed from a figure, not quantified. And the alternative the paper never raises is available: attending to a viscus you cannot feel may recruit visual imagery, and the same contrast activated left frontal eye field and premotor cortex — an oculomotor/imagery signature. Nothing here distinguishes “the stomach is wired to visual cortex” from “people asked to attend to their stomach picture their abdomen.”
Inside the insula: where the two channels come apart
The mass-univariate comparison found a right-anterior cardiac preference. The MVPA found something different and arguably more interesting: a region that does not prefer either channel but encodes which one you are attending to in its multivoxel pattern.
| Insula subdivision | What it did |
|---|---|
| Left PSG (dorsal middle) | Classified cardiac vs gastric at 56.32%, d = 0.61, FDR p = 0.024 — the only significant classifier |
| Right ASG, left ASG, left MSG | Marginal classification (ps = 0.089); higher mean activation for cardiac in the right ASG/MSG |
| Left and right ALG (dorsal posterior) | Marginally higher mean activation for gastric (ps = 0.059, 0.051) |
| Posterior and ventral subdivisions | No classification (ps > 0.27, ds < 0.30) — and no activation above baseline |
Two things follow.
First, viscera-specific coding sits in the MIDDLE insula, not the anterior. The authors claim this as a first: the left dorsal middle insula “codes viscera-specific interoceptive awareness.” It fits the posterior→mid→anterior gradient — organ identity is exactly the kind of thing the mid-insula’s integrative stage should carry — but it means the standard reading of that gradient, in which specificity is progressively discarded on the way to a unified anterior feeling, needs the middle stage to be doing more work than the model usually assigns it. It also gives the first direct evidence on the question Chen et al. (2021) posed and nobody had tested: is there one body map in the insula or several overlapping ones?
Note the caveat on effect size: 56% against a 50% chance level. Real, replicable-looking, and small.
Second, the posterior insula did nothing. Neither discriminating nor active above rest. The authors turn this into a positive claim consistent with Craig: the posterior insula codes ongoing physical change in the bodily signal, and in an attention paradigm there is no homeostatic perturbation to code. That is a coherent reading, and it bears on feedforward-vs-predictive-interoception — but it is an argument from a null in a study with no physiological recording to confirm that nothing was in fact changing.
What it does not show
It is worth being exact, because the paper’s title is broader than its design.
- It measures attention, not awareness, and certainly not accuracy. No detection task, no ground truth, no psychophysics. “Cardiac and gastric interoceptive awareness” in the title is licensed by the assumption — standard in this paradigm, and untested in it — that directing attention to an organ generates awareness of it. See interoceptive-attention-task, interoceptive-taxonomy.
- It says nothing about individual differences. Every result is a group-level contrast. It cannot speak to whether a person good at one channel is good at another; that is Banellis et al.’s question and it was answered separately.
- It does not close the gastric measurement gap. is-interoception-domain-general needs a gastric psychophysical axis to run the decisive three-channel test. This supplies a gastric neural signature, which is not the same currency.