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- Title
Slow cortical oscillations and limb twitches in the neonatal rat.
- Authors
Mcvea, David; Mohajerani, Majid; Murphy, Tim
- Abstract
The developing cerebral cortex is active well before it is functional. This activity manifests as patterns of synchronized membrane depolarization assumed to promote the formation of appropriate afferent inputs as well as integrative cortico-cortico connections. Here, we focus on the role of this activity in the maturation of the sensorimotor cortex by using voltage-sensitive dye (VSD) imaging to study cortical activity in the developing rodent cortex in vivo. Working with postnatal day 5-6 (P5-6) rats, we exposed the cortex via a large (50 mm²) craniotomy. We collected spontaneous changes in VSD fluorescence which reflect underlying membrane potential changes. To determine how peripheral limb twitches affect activity across the cortex, we also collected video signals of peripheral movements. Initially we focused our efforts on the dominant pattern of activity in the developing cortex, the spindle burst. Consisting of a fast (~20 Hz) oscillation atop a slower (~3 Hz) burst, this pattern generally follows afferent input caused by peripheral twitches. We found that VSD imaging provides high-resolution signals of the slow component of spindle bursts (the fast component was poorly reflected in the VSD signal). In the limb somatsensory cortices, this activity followed contralateral limb twitches, while the tail cortex was activated bilaterally by tail twitches. Taking advantage of the wide-imaging area provided by our techniques, we also found that dynamic bursts occasionally moved rapidly across the cortex independently of peripheral twitches. We next examined slower components of the VSD signal, focusing on the infraslow (0.01-0.1 Hz) band. We found that VSD signals were effective at capturing infraslow activity, and that this activity preceded peripheral limb twitches. The coexistence of this slow activity with the subsequent fast, sensory-driven cortical bursts may be a system for calibrating and connecting the sensorimotor system during development.
- Subjects
CEREBRAL cortex; LABORATORY rats; BRAIN function localization; BODY movement; SENSORIMOTOR cortex
- Publication
UBC Medical Journal, 2011, Vol 2, Issue 2, p55
- ISSN
1920-7425
- Publication type
Abstract