title: Categories in the pigeon brain: A reverse engineering approach.
abstract: Pigeons are well known for their visual capabilities as well as their ability to categorize visual stimuli at both the basic and superordinate level. We adopt a reverse engineering approach to study categorization learning: Instead of training pigeons on predefined categories, we simply present stimuli and analyze neural output in search of categorical clustering on a solely neural level. We presented artificial stimuli, pictorial and grating stimuli, to pigeons without the need of any differential behavioral responding while recording from the nidopallium frontolaterale (NFL), a higher visual area in the avian brain. The pictorial stimuli differed in color and shape; the gratings differed in spatial frequency and amplitude. We computed representational dissimilarity matrices to reveal categorical clustering based on both neural data and pecking behavior. Based on neural output of the NFL, pictorial and grating stimuli were differentially represented in the brain. Pecking behavior showed a similar pattern, but to a lesser extent. A further subclustering within pictorial stimuli according to color and shape, and within gratings according to frequency and amplitude, was not present. Our study gives proof-of-concept that this reverse engineering approach-namely reading out categorical information from neural data--can be quite helpful in understanding the neural underpinnings of categorization learning.
authors.affiliation: Biopsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Germany.|International Graduate School of Neuroscience, Ruhr-University Bochum, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Koenen
authors.affiliation: Biopsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Pusch
authors.affiliation: Biopsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Bröker
authors.affiliation: Biopsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Germany.
authors.forename: Samuel
authors.initials: S
authors.lastname: Thiele
authors.affiliation: Biopsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Germany.|International Graduate School of Neuroscience, Ruhr-University Bochum, Germany.
authors.forename: Onur
authors.initials: O
authors.lastname: Güntürkün
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology; D010856:Columbidae / Q000502:physiology*; D003210:Concept Formation / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology; D009415:Nerve Net / Q000502:physiology*; D010775:Photic Stimulation; D014795:Visual Pathways / Q000502:physiology
keywords: NFL; avian brain; categorization; key peck; pigeon; single unit recording