Effects of environment on diverse phases of synaptogenesis

The transition from intrinsic to extrinsic control of synaptogenesis in the cerebral cortex most likely involves many steps. Experience, i.e., the presence of patterned evoked activities coming from the world external to the neocortex, has diverse effects on cortical maturation during the different phases of synaptogenesis. As sketched in figure 2.1, we tentatively propose the following interpretations 1. Phases 1 and 2 of very early synaptogenesis The early events, such as neurogenesis,...

Synaptogenesis In Human Cerebral Cortex

Figure 2.3 Changes in the relative densities of synapses in the primary visual cortex (discontinuous line) and prefrontal cortex (continuous line) of human brain as a function of days after conception expressed on a log scale on the abscissae. Phases 3 and 4 are indicated with numbers 3 and 4. (This is a schematic representation of data published in Huttenlocher and Dabholkar, 1997, with permission from the authors and John Wiley and Sons, Inc.) Figure 2.3 Changes in the relative densities of...

Familiar Words PseudowordsConsonant Strings

Figure 10.6 fMRI results from a single session with an 8-year-old normal reading child performing a repetition detection (one-back) task on familiar words, pseudowords, and consonant strings minus an active fixation monitoring task. Figure 10.6 fMRI results from a single session with an 8-year-old normal reading child performing a repetition detection (one-back) task on familiar words, pseudowords, and consonant strings minus an active fixation monitoring task. child who commanded a large sight...

Markabh Body Part

Purves, 1997. Correlated size variations in human visual cortex, lateral geniculate nucleus, and optic tract. . Neurosci. 17 2859-2868. Amunts, K., G. Schlaug, L. Jaencke, H. Steinmetz, A. Schleicher, A. Dabringhaus, and K. Zilles, 1997. Motor cortex and hand motor skills Structural compliance in the human brain. Hum. Brain Map 5 206-215. Bayer, S. A., andj. Altman, 1991. Neocortical Development. New York Raven Press. Bisconte, J.-C., and R. Marty, 1975a. Analyse...

Development of principal pyramidal and granule cells and nonprincipal GABAergic neurons of the primate hippocampus

Granule cells, hilar mossy cells, and CA3 pyramidal cells of monkeys are in an advanced stage of development at birth (Seress and Ribak, 1995a,b). Most granule cells have a complete dendritic arbor, although both spine density and the number of synapses in the molecular layer increase after birth (Seress, Baumgartner, and Ribak, 1995). Mossy cells and CA3 pyramidal cells display thorny excrescences, and terminals of mossy fibers (axons of granule cells) establish multiple synapses with those...

Sequences of CNS myelination

Historically, in elucidating the factors that determine the topographical and chronological sequences of CNS myelination, the process of myelination has been considered relative to the development of human behavior. This approach resulted in the analysis of the sequence of myelination in terms of relationships among anatomic systems associated with different functions. Yakovlev and Lecours 1967 held that the myelination proceeds along a hierarchy of increasingly complex CNS functions ending in...