Magnetic stimulation of motor cortex in children: maturity of corticospinal pathway and problem of clinical application

Nezua, Atsuo; Kimura, Seiji; Uehara, Saori; Kobayashia, Takuya; Tanaka, Miyabi; Saito, Kaoru

doi:10.1016/s0387-7604(96)00552-9

Cited by 157 publications

(119 citation statements)

References 28 publications

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“…Activity in the low-expanding auditory cortex in response to sound (39) and medial temporal cortex in response to visually presented faces (40,41) can be detected by PET imaging or scalp recording within the first 2 postnatal mo. In contrast, transcranial magnetic stimulation of the high-expanding motor cortex does not elicit detectable muscle response in humans until 2 y of age (42,43).…”

Section: High-expanding Regions Have Greater Cellular Complexity In Amentioning

confidence: 83%

Similar patterns of cortical expansion during human development and evolution

Hill¹,

Inder²,

Neil³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

656

589

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The cerebral cortex of the human infant at term is complexly folded in a similar fashion to adult cortex but has only one third the total surface area. By comparing 12 healthy infants born at term with 12 healthy young adults, we demonstrate that postnatal cortical expansion is strikingly nonuniform: regions of lateral temporal, parietal, and frontal cortex expand nearly twice as much as other regions in the insular and medial occipital cortex. This differential postnatal expansion may reflect regional differences in the maturity of dendritic and synaptic architecture at birth and/or in the complexity of dendritic and synaptic architecture in adults. This expression may also be associated with differential sensitivity of cortical circuits to childhood experience and insults. By comparing human and macaque monkey cerebral cortex, we infer that the pattern of human evolutionary expansion is remarkably similar to the pattern of human postnatal expansion. To account for this correspondence, we hypothesize that it is beneficial for regions of recent evolutionary expansion to remain less mature at birth, perhaps to increase the influence of postnatal experience on the development of these regions or to focus prenatal resources on regions most important for early survival.T he human cerebral cortex is characterized by regional nonuniformities in cellular structure that change with age. Near term, there are regional variations in synaptic density (1, 2), dendritic length, and dendritic spine density (3). Postnatally, synaptic density increases dramatically, reaches a peak density in early childhood, and then undergoes synaptic pruning with a 2-fold or greater reduction (4). The time course of these synaptic changes differs across regions, with primary sensory areas attaining peak density and adult levels earlier than higher order "association" areas (2, 5). In adults, there are large regional nonuniformities in neuronal density (6), dendritic size, branching complexity, and spine density (7).This evidence for cellular nonuniformities provides grounds for anticipating regional differences in macroscopic aspects of postnatal cortical maturation. Indeed, studies of gray matter volume and overall brain growth provide evidence for complex regional patterns of morphological change during childhood and adolescence (8, 9). We recently used a surface-based approach to compare cortical structure in human term infants to adults. That analysis suggested that although many adult cortical shape characteristics are well established at birth, there may be regional differences in the maturity of cortical folding in term infants compared with adults (10).Comparisons with nonhuman primates, especially the intensively studied macaque monkey, provide another basis for evaluating regional differences in cortical maturation. Since the evolutionary divergence between humans and macaques ∼25 million years ago (11), cortical expansion has been far greater in human lineage than in the macaque lineage. Compared with the macaque cortex, the human c...

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Section: High-expanding Regions Have Greater Cellular Complexity In Amentioning

confidence: 83%

Similar patterns of cortical expansion during human development and evolution

Hill¹,

Inder²,

Neil³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

656

589

View full text Add to dashboard Cite

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“…By mid-adolescence, thresholds have decreased to adult levels (Garvey et al, 2003;Moll et al, 1999;Nezu et al, 1997). In children, as in adults, the MEP threshold is higher when the target muscle is at rest (resting motor threshold) than when there is background muscle activation (active motor threshold) (Garvey et al, 2003).…”

Section: Motor Evoked Potential (Mep) Thresholdmentioning

confidence: 99%

Transcranial magnetic stimulation in children

Garvey

Mall

2008

Clinical Neurophysiology

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Developmental disabilities (e.g. attention deficit disorder; cerebral palsy) are frequently associated with deviations of the typical pattern of motor skill maturation. Neurophysiologic tools, such as transcranial magnetic stimulation (TMS), which probe motor cortex function, can potentially provide insights into both typical neuromotor maturation and the mechanisms underlying the motor skill deficits in children with developmental disabilities. These insights may set the stage for finding effective interventions for these disorders. We review the literature pertaining to the use of TMS in pediatrics. Most TMS-evoked parameters show age-related changes in typically developing children and some of these are abnormal in a number of childhood-onset neurological disorders. Although no TMS-evoked parameters are diagnostic for any disorder, changes in certain parameters appear to reflect disease burden or may provide a measure of treatment-related improvement. Furthermore, TMS may be especially useful when combined with other neurophysiologic modalities (e.g. fMRI). However, much work remains to be done to determine if TMS-evoked parameters can be used as valid and reliable biomarkers for disease-burden, the natural history of neurological injury and repair, and the efficacy of pharmacological and rehabilitation interventions.

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“…While transcranial magnetic stimulation has been used to study development of the CS projection to the cord in humans and monkeys (Eyre et al 1991;Nezu et al 1997;Olivier et al 1997), development of the motor representation has only been studied in the cat (Chakrabarty and Martin, 2000). The motor map can be assessed using microstimulation, whereby a microelectrode is used to excite a small population of cortical neurons.…”

Section: Normal and Use Development Of The M1 Mapmentioning

confidence: 99%

“…A human analog to the later period of local refinement-characterized in animals by laminar augmentation of the density and strength of connections Li and Martin, 2001)-may extend until early to mid adolescence. This is because mature TMS response parameters are not observed until these older ages (Eyre et al 1991;Nezu et al 1997;Eyre et al 2000). Intervention during the late developmental period may be akin to the period we examined with the alternate inactivation paradigm in the cat ( Figure 5).…”

Section: Prospects For Harnessing Activity To Restore Cs Connections mentioning

confidence: 99%

Activity- and use-dependent plasticity of the developing corticospinal system☆

Martin

Friel

Salimi

et al. 2007

Neuroscience & Biobehavioral Reviews

128

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The corticospinal system (CS), critical for controlling skilled movements, develops during the late prenatal and early postnatal periods in all species examined. In the cat, there is a sequence of development of the mature pattern of terminations of corticospinal tract axons in the spinal gray matter, followed by motor map development of the primary motor cortex. Skilled limb movements begin to be expressed as the map develops. Development of the proper connections between CS axons and spinal neurons in cats depends on CS neural activity and motor behavioral experience during a critical postnatal period. Reversible CS inactivation or preventing limb use produces an aberrant distribution of CS axon terminations and impairs visually guided movements. This altered pattern of CS connections after inactivation in cats resembles the aberrant pattern of motor responses evoked by transcranial magnetic stimulation in hemiplegic cerebral palsy patients. Left untreated, these impairments do not resolve. We have found that activity-dependent processes can be harnessed in cats to reestablish normal CS connections and function. This finding suggests that CS connectivity and function might some day be restored in hemiplegic cerebral palsy.

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Magnetic stimulation of motor cortex in children: maturity of corticospinal pathway and problem of clinical application

Cited by 157 publications

References 28 publications

Similar patterns of cortical expansion during human development and evolution

Similar patterns of cortical expansion during human development and evolution

Transcranial magnetic stimulation in children

Activity- and use-dependent plasticity of the developing corticospinal system☆

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