Paul J. Reber Department of Psychology Northwestern University Reflections… Paul J. Reber Department of Psychology Northwestern University

Paul J. Reber Department of Psychology Northwestern University How the hell did I end up spending the last 15 years studying “Category Learning”? Paul J. Reber Department of Psychology Northwestern University

“Category Learning” “You do research at Northwestern? What do you study?” Dogs versus Cats, Trees versus Bushes Blah blah blah A PR problem…

What is Category Learning? Ask the Great Gazoogle Link 1: Annual Review of Psych (2005), Ashby & Maddox Link 2: Wikipedia Category:Learning From Wikipedia, the free encyclopedia The main article for this category is Learning. Subcategories There are 5 subcategories in this category, which are shown below. More may be shown on subsequent pages.

What is Category Learning? Dot patterns Unpronounceable strings of letters Sine wave gratings

Dot patterns Learned incidentally Associated with changes in early visual cortex Reber, Stark & Squire, 1998a Reber, Stark & Squire, 1998b Wait. Did you say early visual cortex? There’s plasticity there in the adult brain? For dot patterns? After 40 presentations? Really? Reber at al, 2003

“Learning to see” Crist & Gilbert (2001). Learning to see: experience and attention in primary visual cortex. Nature Neuroscience. Non-classical receptive field effects in early visual cortex Single-cell electrophysiology Task dependent firing changes Schäfer, Vasilaki, & Senn (2007). Perceptual learning via modification of cortical top-down signals. PLoS Computational Biology. How to do perceptual learning in V1 without screwing up perception

Unpronounceable Letter Strings H P J T “Reber” grammar Artificial Grammar Learning Intact in amnesic patients AD patients Posterior parietal cortex Association cortex Symbol manipulation P J X H V X V T +32 G > NG Who called this paradigm “grammar” learning anyway? XTXPHV? That’s not even a word, much less grammatical. Language has deep structure, reference, meaning…

Learning language Saffran (2003). Statistical language learning: mechanisms and constraints. Current Directions in Psych Science. “…Recent evidence suggests that learners, including infants, can use statistical properties of linguistic input to discover structure, including sound patterns, words, and the beginnings of grammar. These abilities appear to be both powerful and constrained…” How much language learning can be done without the frontal lobes? Meaning, reference, deep structure

Implicit learning vs Rule-based Sine wave gratings Category learning with feedback Depends on cortico-striatal loops between the posterior caudate and visual cortex When not accomplished by PFC-MTL If dot patterns = learning to see and AGL = learning language, learning to call stripy things an ‘A’ is… um, learning to drive? learning to play tennis? learning to be a doctor? Implicit learning vs Rule-based (composite)

Diagnosing sleep stage from EEG Expert diagnosticians read continuous collected EEG traces from sleeping individuals and identify occurrence and duration of sleep stages Novices were briefly trained to discriminate REM and Slow Wave sleep from EEG snippets fMRI data collected after 1 day and 1 week of training Opposing movements in the eye channels mark REM sleep

Neural correlates of diagnosis After 1 week of training, increased activity emerged in a cortico-striatal loop Selective for trained stimuli Left Fusiform Right Caudate

“Category Learning” Is everything, after all Learning to see, learning language, expertise Plasticity, memory, categories are everywhere in the brain