AVES (Audiovisual Elicitation of Somatosensation) and ASMR

Efe C. Niven1 and

Sophie K. Scott1,*

Introduction to Audiovisual Elicitation of Somatosensation (AVES)

• The phenomenon commonly referred to on the internet as ASMR (Autonomous Sensory Meridian Response) is characterized by a pleasant sense of touch or a tingling sensation.

• This sensation typically occurs around the scalp, neck, shoulders, and back.

• Authors Efe C. Niven and Sophie K. Scott from the Institute of Cognitive Neuroscience, UCL, propose the term Audiovisual Elicitation of Somatosensation (AVES) as a more accurate description than ASMR.

• ASMR as a term is criticized for not accurately describing the sensory experience or the mechanism by which it is elicited.

• Popularity increase: Over the last decade, online content created to trigger these sensations has surged. In September $2020$, searches for these videos ranked as the third most common on YouTube.

• AVES is described as a perceptual illusion resulting from functional and anatomical links between auditory and somatosensory processing.

Characteristics of AVES-Eliciting Stimuli

• Acoustic Properties:

  • Triggers tend to be quiet sounds.

  • Specific examples include whispered speech and nonverbal sounds like finger tapping or crinkling.

  • Timbre: Stimuli often have a lower spectral centre of gravity, referred to as a "darker" timbre, characterized by a dominance of low frequencies. This aligns with preferences for lower pitch ($7$).

  • Exceptions: Whispered speech has a weak sense of pitch and contains spectral pitch cues. Plosives and fricatives, which are popular triggers, often have a higher spectral centre of gravity.

• Proximal and Spatial Elements:

  • Sounds are typically recorded to seem proximal (very close) to the listener.

  • Use of binaural microphones suggests that AVES may require sounds to be perceived as close to the listener's ears and head specifically.

• Interpersonal and Semantic Factors:

  • Stimuli often involve personal attention roleplays, such as the sounds of a haircut.

  • Emotive language and semantic dialogues creating social interactions are key.

  • Visual information enhances responses through attentional and performative elements.

Neuroanatomical and Functional Integration

• Auditory processing is influenced by somatosensory input starting from the cochlear nucleus and ascending through the auditory pathway to the cortex ($2$).

• Ascending Pathway Mechanisms (Figure 1):

  • The dorsal cochlear nucleus (DCN) and ventral cochlear nucleus (VCN) receive somatosensory inputs.

  • Inputs originate from the trigeminal ganglia (TG), spinal trigeminal nuclei (Sp5), dorsal root ganglia (DRG), and dorsal column nuclei (DCoN) via the marginal cell area of the VCN.

  • Separate inputs exist for the central nucleus (ICc) and external nucleus (ICx) of the inferior colliculi, as well as auditory thalamic nuclei.

  • Projections move from primary ($S1$) and secondary ($S2$) somatosensory cortex to auditory core, belt, and parabelt fields.

  • Thalamic abbreviations: MGd (dorsal nucleus of medial geniculate body), MGm (medial nucleus), MGv (ventral nucleus), PV (posterior ventral nucleus of thalamus), SOC (superior olivary complex).

• Cortex-Level Integration:

  • Caudal-medial auditory fields in nonhuman primates respond to both touch and sound and receive somatosensory field inputs ($3$).

  • An fMRI study ($4$) demonstrated overlapping cortical activation in caudal auditory areas and somatosensory cortex when subjects heard sandpaper rubbing and felt sandpaper texture.

Functional Specialization: Caudal vs. Rostral Auditory Fields

• Caudal Auditory Fields:

  • Neural properties: Short response latencies and transient responses to sound onsets.

  • Sensory input: Primarily somatosensory.

  • Functions: Guiding sound production, processing sounds as actions, and sound-related spatial computations.

  • Proposed role: Critical link in the perception of AVES due to spatial and somatosensory processing connections.

• Rostral Auditory Fields:

  • Neural properties: Long response latencies and slower, sustained responses to sound onsets.

  • Sensory input: Primarily visual.

  • Functions: Recognition processes, connections to semantic networks, and management of multiple auditory streams.

Neural Activation and Physiological Indicators of AVES

• fMRI Observations:

  • Activity is observed in sensation, emotion, attention, and reward networks during AVES.

  • Posterior auditory field activation has been reported ($9$), consistent with the proposed role of caudal auditory areas.

  • Note: The acoustically noisy environment of an fMRI may interact with the AVES experience.

• Physiological Changes:

  • AVES sensations are associated with reliable changes in autonomic responses ($12$).

  • Includes a reduced heart rate and heightened skin conductance.

Individual Differences and Related Phenomena

• Personality Traits:

  • Individuals prone to AVES tend to be more empathetic, more open to experience, and more likely to engage in immersive experiences ($11$).

• Comparisons to Other Experiences:

  • The research questions if AVES is an illusion, a form of synaesthesia, or related to musical "chills."

  • Potential links to "putting teeth on edge" or mirror-touch synaesthesia (experiencing touch from viewing others being touched) ($10$).

• Social and Evolutionary Context:

  • AVES may result from gentle, redirected attention that primes somatosensory responses.

  • The relaxing/pleasant nature of the experience may stem from real-world parallels in trusting, intimate, and affectionate environments.

References Cited in the Text

• 1. Barratt, E.L. and Davis, N.J. ($2015$). ASMR: a flow-like mental state. PeerJ. 3, e851.

• 2. Wu, C. et al. ($2015$). Somatosensory integration in the auditory system. Cell Tissue Res. 361, 233–250.

• 3. Smiley, J.F. et al. ($2007$). Multisensory convergence in auditory cortex. J. Comp. Neurol. 502, 894–923.

• 4. Foxe, J.J. et al. ($2002$). Auditory-somatosensory multisensory processing. J. Neurophysiol. 88, 540–543.

• 5. Jasmin, K. et al. ($2019$). Rostral–caudal auditory cortex contributions. Nat. Rev. Neurosci. 20, 425–434.

• 6. Koumura, T. et al. ($2019$). Deep, soft, and dark sounds induce ASMR. BioRxiv.

• 7. Barratt, E.L. et al. ($2017$). Sensory determinants of ASMR. PeerJ. 5, e3846.

• 8. Liu, M. and Zhou, Q. ($2019$). Digital Video Library on Triggering ASMR: trial among $807$ Chinese college students. Front. Psychol. 10, 2274.

• 9. Smith, S.D. et al. ($2019$). fMRI investigation of ASMR. PeerJ. 7, e7122.

10. Ward, J. and Banissy, M.J. ($2015$). Explaining mirror-touch synesthesia. Cogn. Neurosci. 6, 118–133.

11. McErlean, A.B.J. and Banissy, M.J. ($2017$). Personality and empathy traits in self-reported ASMR. Multisens. Res. 30, 601–613.

12. Poerio, G.L. et al. ($2018$). ASMR characterized by changes in affect and physiology. PLoS One 13, e0196645.