Toward a Deeper Understanding of the Involvement of the Caudate Nucleus in Perceptual Category Learning

1
Toward a Deeper Understanding of the Involvement
of the Caudate Nucleus in Perceptual Category
Learning
J. Scott Lauritzen W. Todd Maddox Institute for
Neuroscience and Department of Psychology, The
University of Texas at Austin
192.10

• Prediction Discontinuous category structures
  should impair non-verbal category learning
  relative to continuous category structures

• Non-verbal category learning is impaired by
  discontinuous category structures and cross-modal
  stimuli
• The locus of the effects for discontinuous
  modality experiments are different
• Deficits with discontinuous stimuli appear to be
  due to sub-optimal caudate unit recruitment
• With cross-modal stimuli many participants employ
  an incorrect (hypothesis-testing) strategy or
  resort to random responding

• Prediction Across-modality stimuli should
  impair non-verbal category learning relative to
  within-modality stimuli

• Two experiments provide empirical evidence that
  differential perceptual stimuli impair learning
  of non-verbalizable category structures

• Procedural learning based system mediates
  learning of non-verbalizable category
  structures 1

• Identical stimulus values used for generation of
  3 types of stimuli
• Each stimulus type pairs different relevant
  stimulus dimensions

• Continuous stimulus values are immediately
  adjacent
• Discontinuous stimulus values introduce
  within-category separation

PFCPrefrontal Cortex GPGlobus Pallidus
SNSubstantia Nigra ThalThalamus HHead of
Caudate BBody of Caudate TTail of Caudate
1 Maddox, W.T., Ashby, F.G.  (2004). 
Dissociating Explicit and Procedural-Learning
Based Systems of Perceptual Category
Learning.  Behavioral Processes.  66,
309-332. 2 Nomura, E.M., Maddox, W.T.,
Filoteo, J.V., Ing, A.D., Gitelman, D.R.,
Parrish, T.B., Mesulam, M-M., Reber, P.J. (Under
Review). Neural Correlates of Rule-Based and
Information-Integration Category Learning. 3
Seger, C.A., Cincotta, C.M. (2005). The Roles
of the Caudate Nucleus in Human Classification
Learning. The Journal of Neuroscience. 25(11),
2941-2951. 4 Saint-Cyr, J.A., Ungerleider,
L.G., Desimone, R. (1990). Organization of
Visual Cortical Inputs to the Striatum and
Subsequent Outputs to the Pallido-Nigral Complex
in the Monkey. The Journal of Comparative
Neurology. 298(2), 129-156. 5 Wilson, C.J.
(1995). The Contribution of Cortical Neurons to
the Firing Pattern of Striatal Spiny Neurons.
(pp. 29-50). Cambridge, MA MIT Press. 6
Yeterian, E.H. Pandya, D.N. (1998).
Corticostriatal Connections of the Superior
Temporal Region in Rhesus Monkeys. The Journal
of Comparative Neurology. 399, 384-402.
The caudate nucleus, in conjunction with other
structures, mediates non-verbal category
learning 2,3

• Caudate nucleus receives many-to-one
  convergence of input from perceptual areas 4
• Differential input into the caudate nucleus
  across sensory modalities 5,6
• Visual input exclusively into tail 5
• Auditory input into head, body, and tail 6
• Hypothesis Perceptually dissimilar items
  project to different functional units in the
  caudate, adversely affecting non-verbal
  category learning.

• Human participants view a series of images and
  categorize each image

Acknowledgements This research was supported in
part by National Institute of Health Grant R01
MH59196 to WTM, and a McDonnell-Pew Consortium
Grant.

• Discontinuous categories impair learning
• Caudate has difficulty associating perceptually
  distinct stimuli with the same response

• Participants displayed deficits with cross-modal
  stimuli relative to within-modal stimuli
• Differential sensory input to the caudate nucleus
  may account for the observed deficits

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