Author: ctsadmin

Mismatch Negativity (MMN) Predicts Pattern Separation
Deena Herman1 and Stevenson Baker1, ,Jaime Cazes1, Claude Alain2,3, Shayna Rosenbaum1,2
1York University, Toronto, Canada; 2Rotman Research Institute at Baycrest Hospital, Toronto, Canada, 3Department of Psychology, University of Toronto, Canada 1York University, Toronto 2Baycrest, Toronto 3Harvard University

INTRODUCTION

MethodS: Study phase

RESULTS: Test phase

Background
Pattern separation: A memory process whereby highly similar stimuli are encoded in non-overlapping representations
→ typically studied in the visual domain with previously known stimuli (e.g., objects)
Mismatch negativity (MMN): An event-related potential (ERP) indexing the brain’s perceptual discrimination
→ typically studied in the auditory domain with abstract sounds (e.g., pure tones)
→ Humans can detect novelty within hundreds of ms, as measured by the MMN
Theory
Predictive error: mechanisms of hierarchical inference, such as predictive error, are responsible for the MMN and also facilitate pattern separation
Question
Although similar processes may support MMN and pattern separation, little attention has been paid to how they are correlated
→ to what extent does our capacity to discriminate auditory inputs, as measured by the MMN, influence mnemonic discrimination of long-term memories?

METHODS: Participants & Stimuli

Participants
31 young adults (YA), age range 18–32, 18 female
Stimuli
Six novel auditory sound patterns: non-melodic and non-semantic
Five of the six comprised of the same five 100-ms tones arranged in different order
→ Foil micropattern pitched lower
Study micropatterns: Standard and Deviant
Test micropatterns: Standard and Deviant, as well as three Lures and one Foil

Experimental Micropatterns ─ Six Auditory Sound Patterns

Passive listening (25 minutes):
Participants watched a muted movie while listening to random presentations of Standard and Deviant micropatterns
→ Event-related potentials measured to determine the existence and strength of an MMN signal

results: Study phase

Average frontal-central pole (FCz) ERPs in response to the standard (blue) and the deviant (red) micropatterns. The dotted black line indicates the MMN waveform.

t = <.001

CLARA source analysis. Red and yellow shading represents areas of the brain at this latency where deviant micropattern activity is significantly greater (P<.001) than standard micropattern activity.

Methods: Test phase

Test Phase
Evaluation of participants’ recognition memory
The six micropatterns (two old, three lures, one foil) were presented ten times each over the course of the test phase, for a total of 60 trials, in randomized order
Participants indicated via a button press whether or not they heard the tone while watching the movie
the movie

To verify that the MMN predicted behavioral pattern separation, we correlated the MMN amplitudes with recognition d’ scores for lure discrimination, d’ (O,L)
After correcting for multiple comparisons, we found the MMN was significantly related with d’ (O,L), r = –.40, 95% BCa CI [–.69, –.02], p = .013, one-tailed.

MMN correlation with pattern separation

r = .40

CONCLUSION

The primary finding that the MMN and d’ (O,L) are correlated is consistent with our prediction that strong mnemonic representation is formed from the MMN and that it predicts pattern separation
Therefore, the MMN paradigm provides a test of both recognition memory and pattern separation for auditory objects
Our investigation is the first to show that our capacity to discriminate auditory inputs, as measured by MMN, gives rise to unique, long-term memories

REFERENCES

Garrido, M. I., Kilner, J. M., Stephan, K. E., & Friston, K. J. (2009). The mismatch negativity: A review of underlying mechanisms. Clinical Neurophysiology, 120(3), 453-463.
Näätänen, R., Kujala, T., Light, G., & Oxford Scholarship Online – York University. (2019) The mismatch negativity: A window to the brain (First edition). Oxford University Press.
Rolls, E. T. (2016). Pattern separation, completion, and categorisation in the hippocampus and neocortex. Neurobiology of Learning and Memory, 129, 4–28.
Schröger, E. (1994). An event-related potential study of sensory representations of unfamiliar tonal patterns. Psychophysiology, 31(2), 175–181.

ACKNOWLEDGEMENTS

Yasha Amani, Ricky Chow, Jad Daou, and Yarden Levy