Beyond the Five Senses: What Gut–Brain Research Reveals About Human Memory

Understanding the Biological Complexity of Memory and Its Relevance to Investigative Interviewing

When we ask someone to recall an event, we generally consider the information available to that person: what they saw, heard, experienced, and attended to at the time.

We may also consider stress, emotion, expectations, and the conditions under which the person is subsequently interviewed.

But what about physiological processes occurring inside the body?

Could signals originating in the gastrointestinal system influence the neural mechanisms involved in remembering an experience?

Research examining the relationship between food consumption, gut–brain communication, and memory suggests that certain physiological signals can influence memory-related processes.

These internal signals do not constitute an additional form of episodic memory. Rather, they illustrate how biological systems beyond external sensory processing may influence neural mechanisms involved in learning and remembering.

If biological processes influence memory, what might this tell us about the conditions under which experiences are encoded, retained, and later retrieved?

The answer requires distinguishing what research demonstrates, what it suggests, and what remains unknown.

The Science: Memory Extends Beyond Sensory Experience

The hippocampus plays an important role in learning and memory, including the encoding and retrieval of information about experienced events.

Research by Dr. Scott Kanoski and colleagues has explored how biological systems traditionally associated with appetite, digestion, and energy regulation interact with hippocampal memory functions.

In a 2019 review, Suarez, Noble, and Kanoski examined evidence involving the vagus nerve and feeding-related hormones, including ghrelin, insulin, leptin, and glucagon-like peptide-1 (GLP-1).

Their review identified experimental findings linking these biological systems to hippocampal-dependent learning and memory.

The brain receives information not only from the external environment but also from the body's internal physiological condition.

These internal signals, described as interoceptive information, can interact with neural systems involved in learning and memory.

Importantly, much of the research identifying specific biological mechanisms comes from animal studies. These findings do not establish equivalent effects on the accuracy of human recollections obtained during investigative interviews.

Memory and Eating: A Bidirectional Relationship

One particularly interesting finding is that memory and eating can influence each other.

Food consumption and associated physiological processes can affect memory-related systems. Conversely, remembering a previous eating experience can influence subsequent food consumption.

In a review published in Neuroscience & Biobehavioral Reviews, Parent, Higgs, Cheke, and Kanoski (2022) examined experimental evidence involving memory, eating behavior, and hippocampal functioning.

The authors reviewed human studies demonstrating that remembering a recently consumed meal can influence subsequent eating behavior.

They also examined research involving individuals with amnesia, in whom impaired memory of recent meals can contribute to altered eating behavior.

These findings illustrate that memory is not simply a passive record of experience. Remembered information can contribute to subsequent behavior.

However, findings involving eating-related memories do not establish that similar mechanisms necessarily influence the accuracy of recollections concerning complex investigative events.

Where Does GLP-1 Fit Into This Research?

GLP-1 is a hormone involved in metabolic regulation and appetite-related signaling. Its receptors are also found in brain systems associated with learning and memory.

Experimental research, conducted predominantly in animal models, indicates that GLP-1 receptor signaling can influence hippocampal-dependent learning and memory under certain conditions, as reviewed by Suarez and colleagues (2019).

Some experimental findings suggest effects on neural plasticity and performance in particular memory tasks.

These discoveries are scientifically interesting because they demonstrate potential relationships between metabolic signaling and memory-related neural processes.

However, several distinctions are essential.

First, naturally occurring GLP-1 signaling should not automatically be equated with the effects of pharmaceutical GLP-1 receptor agonists.

Second, improvements in laboratory memory tasks do not necessarily translate into more accurate recollections of complex real-world experiences.

Third, whether these findings translate into meaningful improvements in human episodic memory remains unresolved.

Current research does not establish that GLP-1 medications improve the completeness or reliability of recollections obtained during investigative interviews.

Making the Connection to the Cognitive Interview

The Cognitive Interview (CI), developed through research by Drs. Ronald Fisher and R. Edward Geiselman, incorporates retrieval-support principles derived from cognitive psychology.

One established component involves mentally reinstating relevant contextual features associated with an experienced event.

Contextual reinstatement seeks to facilitate memory retrieval through cues related to the original experience. Research examining the Cognitive Interview and its components provides empirical support for this approach, as discussed by Memon and Bull (1991).

Gut–brain research examines a different scientific question: how physiological signals originating within the body may interact with neural systems supporting learning and memory.

These findings invite consideration of a possible relationship between internal physiological conditions and memory processes.

But a relationship between biological signaling and memory does not establish a relationship between those signals and Cognitive Interview effectiveness.

Whether gut–brain mechanisms interact with contextual retrieval processes in ways relevant to investigative interviewing has not been established.

That question requires direct empirical investigation.

The legitimate connection is therefore conceptual: the biological complexity of memory reinforces the importance of understanding the conditions under which experiences are encoded and subsequently retrieved.

It does not establish a new interviewing technique.

What Might Future Research Explore?

Research concerning gut–brain communication raises several questions that may be relevant to future studies of episodic memory and investigative interviewing.

1. Do measurable physiological conditions influence the encoding of complex, personally experienced events?

Researchers could examine whether internal physiological conditions contribute to differences in encoding while accounting for established influences such as attention, perception, and emotional arousal.

2. Do those conditions influence later episodic retrieval independently of established cognitive and contextual factors?

This question would require distinguishing effects on initial memory formation from effects occurring during subsequent retrieval.

3. If such effects exist, are they sufficiently reliable and meaningful to influence the completeness or accuracy of information obtained during interviews?

This final question is particularly important. Demonstrating a biological influence on memory performance does not establish that the influence has practical significance for investigative interviewing.

Research would need to involve appropriate human experimental designs, meaningful memory outcomes, and careful evaluation of possible confounding variables.

These questions are proposed directions for scientific investigation, not claims of demonstrated interviewing benefits.

Table 1. Gut–Brain Communication, Human Memory, and Investigative Interviewing: Current Evidence and Research Boundaries

Research area	What current research supports	What remains unestablished
Gut–brain communication	Gastrointestinal and metabolic signals interact with neural systems involved in learning and memory.	How these mechanisms influence the accuracy of complex human episodic recollections.
GLP-1 signaling	Experimental studies, predominantly in animals, demonstrate effects on certain hippocampal-dependent learning and memory processes.	Whether GLP-1 medications improve the completeness or accuracy of human episodic recollections.
Memory and eating	Human research demonstrates that remembering previous meals can influence subsequent food consumption.	Whether these findings generalize to recollections of consequential events in investigative settings.
Physiological context	Internal physiological conditions can interact with memory-related biological processes.	Whether reinstating an individual's original physiological state improves subsequent episodic retrieval.
Cognitive Interview (CI)	Research supports the CI as a method for facilitating information retrieval, including contextual reinstatement techniques.	Whether manipulating gut–brain signaling or physiological conditions improves CI performance.

Evidence summary based on Suarez et al. (2019), Parent et al. (2022), Décarie-Spain et al. (2024), and Memon and Bull (1991). The absence of established evidence for an application does not demonstrate that the proposed effect is impossible.

What the Current Research Does Not Support

Scientific integrity requires identifying the boundaries of available evidence.

At present, research does not establish that:

• GLP-1 medications improve the accuracy or completeness of investigative recollections.

• Consuming particular foods before an interview improves episodic-memory retrieval.

• Reinstating hunger, fullness, or other metabolic conditions experienced during an event improves Cognitive Interview performance.

• An individual's nutritional or metabolic condition can independently establish the reliability of a remembered account.

• Findings from hippocampal-dependent animal memory tasks necessarily generalize to human recollections of consequential real-world experiences.

These limitations do not diminish the value of the underlying research.

They distinguish evidence demonstrating biological mechanisms from evidence validating professional applications.

What This Means for Investigative Interviewing

The purpose of scientifically informed investigative interviewing is to facilitate the most complete and reliable account possible while respecting the known characteristics and limitations of human memory.

Research involving gut–brain communication provides another perspective on the complexity of the systems supporting memory.

It suggests that memory-related processes are influenced by interacting biological systems rather than operating independently of the body's physiological condition.

A 2024 review by Décarie-Spain and colleagues further examined gastrointestinal vagal signaling and its relationship to higher-order cognitive functions, including learning and memory.

For investigators, aviation safety professionals, healthcare event reviewers, and others who obtain accounts of past experiences, these findings provide an opportunity to broaden scientific understanding.

They do not currently justify modifying established interviewing procedures.

Understanding more about how memory operates is not the same as demonstrating that a particular intervention improves memory retrieval.

Both are worthwhile scientific objectives, but they require different kinds of evidence.

Take It Forward

The next time we consider how someone remembers an event, it may be useful to recognize that memory is supported by a complex biological system influenced by more than information acquired through external sensory experience.

That observation invites further scientific inquiry.

It does not authorize unsupported conclusions about an individual's recollection or justify changes to established interviewing practices without appropriate empirical validation.

Emerging discoveries involving gut–brain communication may eventually contribute to our understanding of human memory and the conditions influencing information retrieval.

For now, the scientifically responsible position remains straightforward:

Understand what the research establishes. Explore what it may suggest. Remain clear about what it has not yet demonstrated.

That distinction is essential to advancing the science and practice of human information gathering.

References

Suarez, A. N., Noble, E. E., & Kanoski, S. E. (2019). Regulation of memory function by feeding-relevant biological systems: Following the breadcrumbs to the hippocampus. Frontiers in Molecular Neuroscience, 12, Article 101.

Parent, M. B., Higgs, S., Cheke, L. G., & Kanoski, S. E. (2022). Memory and eating: A bidirectional relationship implicated in obesity. Neuroscience & Biobehavioral Reviews, 132, 110–129.

Décarie-Spain, L., Hayes, A. M. R., Lauer, L. T., & Kanoski, S. E. (2024). The gut-brain axis and cognitive control: A role for the vagus nerve. Seminars in Cell & Developmental Biology, 156, 201–209.

Memon, A., & Bull, R. (1991). The cognitive interview: Its origins, empirical support, evaluation and practical implications. Journal of Community & Applied Social Psychology, 1(4), 291–307.