Neuroscience 2003 Abstract
| Presentation Number: | 126.8 |
|---|---|
| Abstract Title: | Receptive field properties of MT neurons in infant macaques. |
| Authors: |
Movshon, J. A.*1
; Rust, N. C.1
; Kohn, A.1
; Kiorpes, L.1
; Hawken, M. J.1
1HHMI & Ctr. Neural Sci, New York Univ, New York, NY |
| Primary Theme and Topics |
Sensory Systems - Vision -- Visual cortex: Functional organization and circuitry |
| Secondary Theme and Topics | Development<br />- Development of Sensory and Limbic Systems<br />-- Visual system |
| Session: |
126. Visual Cortex: Plasticity, Learning & Development Slide |
| Presentation Time: | Sunday, November 9, 2003 9:45 AM-9:45 AM |
| Location: | Morial Convention Center - Room 287 |
| Keywords: | development, visual cortex, motion, directional |
Neurons in MT (V5) of adult macaques are almost all selective for the direction of motion, and are very sensitive both to contrast and to motion signals imbedded in noise. Many MT neurons are also 'pattern direction selective' (PDS) and signal the true global motion of complex objects. Psychophysical motion sensitivity is poor in infant monkeys, and we wondered whether this reflects the postnatal development of the response properties of MT neurons.
We studied the visual responses of MT neurons in opiate anesthetized, paralyzed infant monkeys aged 1, 4, and 16 weeks. We analyzed directional selectivity, spatial and temporal frequency tuning, contrast sensitivity, sensitivity to pattern motion, and sensitivity to motion in random-dot kinematograms (RDKs) of varying coherence.
MT neurons in infants were similar in their response properties to those in adults: almost all were direction selective, and many had relatively high contrast sensitivity. As in adults, a substantial minority were PDS, and some retained their direction selectivity even at low motion coherence for RDKs. At the ages of 1 and 4 weeks, neuronal responses were usually less vigorous than in older animals, and spatial resolution was poorer. The most striking differences between these responses and those in adults were in temporal properties: visual latency was substantially longer, and responses to drifting gratings of high temporal frequency were weaker. Nonetheless, all the main features of adult MT receptive fields were evident in recordings from even the youngest infants.
Our results suggest that substantial postnatal visual experience is not needed to establish such basic properties of MT neurons as direction selectivity. During postnatal maturation, the temporal precision and vigor of neuronal responses are enhanced without altering the basic organization of receptive fields.
We studied the visual responses of MT neurons in opiate anesthetized, paralyzed infant monkeys aged 1, 4, and 16 weeks. We analyzed directional selectivity, spatial and temporal frequency tuning, contrast sensitivity, sensitivity to pattern motion, and sensitivity to motion in random-dot kinematograms (RDKs) of varying coherence.
MT neurons in infants were similar in their response properties to those in adults: almost all were direction selective, and many had relatively high contrast sensitivity. As in adults, a substantial minority were PDS, and some retained their direction selectivity even at low motion coherence for RDKs. At the ages of 1 and 4 weeks, neuronal responses were usually less vigorous than in older animals, and spatial resolution was poorer. The most striking differences between these responses and those in adults were in temporal properties: visual latency was substantially longer, and responses to drifting gratings of high temporal frequency were weaker. Nonetheless, all the main features of adult MT receptive fields were evident in recordings from even the youngest infants.
Our results suggest that substantial postnatal visual experience is not needed to establish such basic properties of MT neurons as direction selectivity. During postnatal maturation, the temporal precision and vigor of neuronal responses are enhanced without altering the basic organization of receptive fields.
Supported by National Eye Institute, NIH
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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