Tuning for shape dimensions in macaque inferior temporal cortex
- 19 July 2005
- journal article
- Published by Wiley in European Journal of Neuroscience
- Vol. 22 (1) , 212-224
- https://doi.org/10.1111/j.1460-9568.2005.04202.x
Abstract
It is widely assumed that distributed bell‐shaped tuning (e.g. Radial Basis functions) characterizes the shape selectivity of macaque inferior temporal (IT) neurons, analogous to the orientation or spatial frequency tuning found in early visual cortex. Demonstrating such tuning properties requires testing the responses of neurons for different values along dimensions of shape. We recorded the responses of single macaque IT neurons to variations of a rectangle and a triangle along simple shape dimensions, such as taper and axis curvature. The neurons showed systematic response modulation along these dimensions, with the greatest response, on average, to the highest values on the dimensions, e.g. to the most curved shapes. Within the range of values tested, the response functions were monotonic rather than bell‐shaped. Multi‐dimensional scaling of the neural responses showed that these simple shape dimensions were coded orthogonally by IT neurons: the degree and direction of responses modulation (i.e. the increase or decrease of responses along a dimension) was independent for the different dimensions. Furthermore, for combinations of curvature‐related and other simple shape dimensions, the joint tuning was separable, that is well predicted by the product of the tuning for each of the dimensions. The independence of dimensional tuning may provide the neural basis for the independence of psychophysical judgements of multidimensional stimuli.Keywords
This publication has 37 references indexed in Scilit:
- The Integration of Multiple Stimulus Features by V1 NeuronsJournal of Neuroscience, 2004
- Parts and relations are analyzable sources of shape variation: Evidence for structural descriptionsJournal of Vision, 2004
- Underlying principles of visual shape selectivity in posterior inferotemporal cortexNature Neuroscience, 2004
- Computing with Populations of Monotonically Tuned NeuronsNeural Computation, 2003
- Impact of learning on representation of parts and wholes in monkey inferotemporal cortexNature Neuroscience, 2002
- Empirical evidence for independent dimensions in the visual representation of three-dimensional shape.Journal of Experimental Psychology: Human Perception and Performance, 2002
- Inferotemporal Cortex and Object VisionAnnual Review of Neuroscience, 1996
- Shape representation in the inferior temporal cortex of monkeysCurrent Biology, 1995
- Using confidence intervals in within-subject designsPsychonomic Bulletin & Review, 1994
- Identification and ratings of caricatures: Implications for mental representations of facesCognitive Psychology, 1987