PT  - JOURNAL ARTICLE
AU  - Tijl Grootswagers
AU  - Radoslaw M. Cichy
AU  - Thomas A. Carlson
TI  - Finding decodable information that is read out in behaviour
AID  - 10.1101/248583
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 248583
4099  - http://biorxiv.org/content/early/2018/01/16/248583.short
4100  - http://biorxiv.org/content/early/2018/01/16/248583.full
AB  - Multivariate decoding methods applied to neuroimaging data have become the standard in cognitive neuroscience for unravelling statistical dependencies between brain activation patterns and experimental conditions. The current challenge is to demonstrate that information decoded as such by the experimenter is in fact used by the brain itself to guide behaviour. Here we demonstrate a promising approach to do so in the context of neural activation during object perception and categorisation behaviour. We first localised decodable information about visual objects in the human brain using a spatially-unbiased multivariate decoding analysis. We then related brain activation patterns to behaviour using a machine-learning based extension of signal detection theory. We show that while there is decodable information about visual category throughout the visual brain, only a subset of those representations predicted categorisation behaviour, located mainly in anterior ventral temporal cortex. Our results have important implications for the interpretation of neuroimaging studies, highlight the importance of relating decoding results to behaviour, and suggest a suitable methodology towards this aim.Significance statement Brain decoding methods are a powerful way to analyse neuroimaging data. An implicit assumption in many decoding studies is that when information can be decoded, then the brain is using this information for behaviour. However, this assumption must be explicitly tested. Here, using visual object categorisation as an example, we separately localised decodable information and information that can be used to predict behaviour. Our findings showed that only from a subset of areas that had decodable category information, we could predict observer categorisation reaction times. Our results highlight the distinction between decodable information and information that is suitably formatted for read-out by the brain in behaviour. Our results have critical implications for the interpretation of decoding studies in general.