N. Scott Bradley

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This paper presents ILGM (the Infant Learning to Grasp Model), the first computational model of infant grasp learning that is constrained by the infant motor development literature. By grasp learning we mean learning how to make motor plans in response to sensory stimuli such that open-loop execution of the plan leads to a successful grasp. The open-loop(More)
Based on studies using direct observation methods, type I motility, the first motility pattern to emerge in chick embryos, is characterized as random, uncoordinated movement. Yet, electromyographic (EMG) studies indicate that leg muscles are recruited in orderly patterns of alternating flexor and extensor activity during type I motility. It has been(More)
From birth to postnatal day 60, neuromuscular patterns for airstepping and treadmill stepping were assessed in kittens spinalized (T12) at birth (Day-1) or at the end of the second postnatal week (Day-14). Within 72 h after spinalization, all kittens displayed stepping motions, but exteroceptive facilitation (e.g. tail pinch) was required to initiate and(More)
We examined muscle burst patterns and burst frequencies for a distinct form of repetitive leg movement recently identified in chick embryos at embryonic day (E)18 that had not been previously studied. The aim was to determine if burst frequencies during repetitive leg movements were indicative of a rhythm burst generator and if maturing muscle afferent(More)
Over the course of embryonic development, chick embryos express 3 different types of motility (I, II, III). Although neural pattern generators appear to control embryonic motility, the mechanisms responsible for the sequential emergence and/or transformations in these behaviors are not known. Given the early presence of functional sensory connections and(More)
Soon after hatching, chicks exhibit an array of adaptive, coordinated behaviors. Chick embryos also acquire nearly 18 days of movement experience, referred to as embryonic motility, before hatching. The chick expresses three forms of motility, types I, II, and III, and each emerges at a different stage of embryonic development. Although much is known about(More)
Neuromuscular patterns of scratching and the paw-shake response were studied in normal kittens from birth to postnatal day 60. Onset of both behaviors coincided with the development of secure weight-bearing posture and occurred on postnatal day 21 for scratching and postnatal day 26 for paw shaking. At onset, cycle periods for scratching (5-6 Hz) and paw(More)
New imaging technologies are revealing ever-greater details of motor behavior in fetuses for clinical diagnosis and treatment. Understanding the form, mechanisms, and significance of fetal behavior will maximize imaging applications. The chick is readily available for experimentation throughout embryogenesis, making it an excellent model for this purpose.(More)
Neuromuscular patterns associated with the development of hindlimb stepping behaviors were studied from birth to postnatal day 60 in normal kittens. Hindlimb muscles were chronically implanted with EMG electrodes at birth to characterize interlimb coordination and intralimb synergies during development of overground and treadmill stepping. Airstepping was(More)
Tactile placing and associated responses of the fore and hind paws to a light tactile stimulus were studied in normal young-adult cats and kittens and their spinal littermates. All spinal transections were performed at T12 on the 14th postnatal day. In the first study, responses of normal and spinal young-adult cats were compared at 9 to 10 months of age.(More)