Spatiotemporal brain dynamics of auditory temporal assimilation

Area of Science:

• Cognitive Neuroscience
• Psychophysics
• Neuroimaging

Background:

• Accurate perception of time is crucial, yet millisecond-level temporal judgments are susceptible to perceptual illusions.
• Auditory temporal assimilation (ATA) is a phenomenon where perceived durations of successive intervals can be distorted, leading to illusions like the 'time-shrinking illusion'.

Purpose of the Study:

• To investigate the neural underpinnings of human temporal judgments, specifically focusing on the spatiotemporal profile of the time-shrinking illusion.
• To identify brain regions involved in encoding temporal intervals and perceiving illusory temporal equality.

Main Methods:

• Utilized magnetoencephalography (MEG) combined with a psychological paradigm inducing auditory temporal assimilation (ATA).
• Analyzed behavioral data to confirm the time-shrinking illusion (perceived equality when T2 - T1 ≤ +80 ms).
• Applied MEG source-localization to differentiate brain activity between temporal judgment and no-judgment conditions.

Main Results:

• Behavioral data confirmed the time-shrinking illusion, with participants judging unequal intervals as equal within a specific range.
• MEG analysis revealed distinct regional activity differences in the temporoparietal junction (TPJ) during T2, suggesting its role in encoding unequal intervals.
• Enhanced activation in the inferior frontal gyrus (IFG) was observed during temporal judgment and specifically correlated with the time-shrinking illusion after the final stimulus.

Conclusions:

• The temporoparietal junction (TPJ) appears involved in the neural encoding of temporal interval differences.
• The inferior frontal gyrus (IFG) plays a role in the cognitive process of temporal judgment and is specifically implicated in the illusory perception of time-interval equality.
• These findings propose distinct neural signatures for the judgment of temporal equality, contributing to our understanding of time perception and its distortions.