Regional Specialization in Pyramidal Cell Structure in the Visual Cortex of the Galago: An Intracellular Injection Study of Striate and Extrastriate Areas with Comparative Notes on New World and Old World Monkeys

Elston, Guy N.; Elston, Alejandra; Kaas, J.H.; Casagrande, Viviana

doi:10.1159/000085044

Cited by 27 publications

(18 citation statements)

References 103 publications

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“…Cells become increasingly larger and more spinous with anterior progression through visual areas V1, V2, V4, TEO, and TE (Elston and Rosa, 1997, 1998; Elston et al, 1999b, 2005b,d,e; Elston, 2003b). Likewise, cells become increasingly larger and more spinous with progression through somatosensory areas 3b, 5, and 7 (Elston and Rockland, 2002; Elston et al, 2005h,i).…”

Section: Specialized Pyramidal Cell Growth Profiles Results In Specialmentioning

confidence: 99%

Pyramidal cell development: postnatal spinogenesis, dendritic growth, axon growth, and electrophysiology

Elston¹,

2014

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Here we review recent findings related to postnatal spinogenesis, dendritic and axon growth, pruning and electrophysiology of neocortical pyramidal cells in the developing primate brain. Pyramidal cells in sensory, association and executive cortex grow dendrites, spines and axons at different rates, and vary in the degree of pruning. Of particular note is the fact that pyramidal cells in primary visual area (V1) prune more spines than they grow during postnatal development, whereas those in inferotemporal (TEO and TE) and granular prefrontal cortex (gPFC; Brodmann's area 12) grow more than they prune. Moreover, pyramidal cells in TEO, TE and the gPFC continue to grow larger dendritic territories from birth into adulthood, replete with spines, whereas those in V1 become smaller during this time. The developmental profile of intrinsic axons also varies between cortical areas: those in V1, for example, undergo an early proliferation followed by pruning and local consolidation into adulthood, whereas those in area TE tend to establish their territory and consolidate it into adulthood with little pruning. We correlate the anatomical findings with the electrophysiological properties of cells in the different cortical areas, including membrane time constant, depolarizing sag, duration of individual action potentials, and spike-frequency adaptation. All of the electrophysiological variables ramped up before 7 months of age in V1, but continued to ramp up over a protracted period of time in area TE. These data suggest that the anatomical and electrophysiological profiles of pyramidal cells vary among cortical areas at birth, and continue to diverge into adulthood. Moreover, the data reveal that the “use it or lose it” notion of synaptic reinforcement may speak to only part of the story, “use it but you still might lose it” may be just as prevalent in the cerebral cortex.

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Section: Specialized Pyramidal Cell Growth Profiles Results In Specialmentioning

confidence: 99%

Pyramidal cell development: postnatal spinogenesis, dendritic growth, axon growth, and electrophysiology

Elston¹,

2014

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“…10F). Elston and collaborators (Elston et al, 1996(Elston et al, , 2005Elston, 2003), on the other hand, have compared the dendritic morphologies of layer 3 pyramidal neurons across several higher order visual areas in primates. Their detailed work showed that dendritic morphology of neurons becomes more complex as one proceeds along the hierarchy, but the neurons described were not retrogradely labeled through tracer injections to identify feedback neurons.…”

Section: Discussionmentioning

confidence: 99%

Parallel feedback pathways in visual cortex of cats revealed through a modified rabies virus

Connolly

Hashemi-Nezhad

Lyon

2012

J of Comparative Neurology

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The visual cortex of cats is highly evolved. Analogously to the brains of primates, large numbers of visual areas are arranged hierarchically and can be parsed into separate dorsal and ventral streams for object recognition and visuospatial representation. Within early primate visual areas, V1 and V2, and to a lesser extent V3, the two streams are relatively segregated and relayed in parallel to higher order cortex, although there is some evidence suggesting an alignment of V2 and V3 to one stream over the other. For cats, there is no evidence of anatomical segregation in areas 18 and 19, the analogs to V2 and V3. However, previous work was only qualitative in nature. Here we re-examined the feedback connectivity patterns of areas 18/19 in quantitative detail. To accomplish this, we used a genetically modified rabies virus that acts as a retrograde tracer and fills neurons with fluorescent protein. After injections into area 19, many more neurons were labeled in putative ventral stream area 21a than in putative dorsal stream region posterolateral suprasylvian complex of areas (PLS), and the dendrites of neurons in 21a were significantly more complex. Conversely, area 18 injections labeled more neurons in PLS, and these were more complex than neurons in 21a. We infer from our results that area 19 in cat is more aligned to the ventral stream and area 18 to the dorsal stream. Based on the success of our approach, we suggest that this method could be applied to resolve similar issues related to primate V3.

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“…In general, where neuron densities are highest (in V1 for example) the basilar dendritic spine densities are lowest, and where the neuron densities are lowest (in frontal and motor cortices) the spine densities tend to be the highest in all species of primates examined to date. Detailed examinations of pyramidal cell spine densities in visual cortical areas, including V1, V2, and more rostral extrastriate areas, show a predictable increase in spine densities in more rostral locations compared to V1 in prosimians [Elston et al, 2005] and New World [Elston et al, 1996] and Old World monkeys [Elston et al, 2006a]. In sensorimotor cortical areas in macaque monkeys there was a trend for increasing spine density and dendritic arbor complexity from S1 (3b), which has a relatively high neuron density and low spine densities, to nearby more caudally positioned areas such as somatosensory area 5 and parietal area 7b.…”

Section: Regional Variation In Cell Morphologymentioning

confidence: 94%

Variability in Neuron Densities across the Cortical Sheet in Primates

Collins¹

2011

Brain Behav Evol

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The function of any area of the brain is a product of its unique population of neurons and nonneurons and their local and long-range connectional architecture. At the present time, we have inadequate data about numbers of neurons and the distribution patterns of neurons in the cortex and other parts of the brain. Numbers and densities of neurons and nonneurons provide the foundation for the assembly of a cortical and whole-brain neuronal network, yet the majority of studies reporting neuron densities for the primate cortex estimate the number of neurons in the cortex as a whole or in specific areas for comparisons between treatment groups or species. While this is valuable information for studies of scaling or comparative studies of specific pathways or functions, a more detailed examination of cell and neuron number distribution across the entire cortical expanse is needed. Two studies reviewed here use the isotropic fractionator method for the determination of cell and neuron numbers to investigate the distribution of cells and neurons across the entire cortical sheet of 4 primate species, taking into consideration cortical areal boundaries. Neuron and total cell numbers were found to vary as much as 5 times between different functional areas across the cortical sheet. Numbers were also variable across representational zones within cortical areas like V1 and S1. The overall distribution of cells and neurons appears to be conserved across the species examined, suggesting a common plan for cell distribution in primates, with more areas of high neuron density in macaques and baboons compared to the smaller and less differentiated cortex of prosimian galagos and the New World owl monkey.

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Regional Specialization in Pyramidal Cell Structure in the Visual Cortex of the Galago: An Intracellular Injection Study of Striate and Extrastriate Areas with Comparative Notes on New World and Old World Monkeys

Cited by 27 publications

References 103 publications

Pyramidal cell development: postnatal spinogenesis, dendritic growth, axon growth, and electrophysiology

Pyramidal cell development: postnatal spinogenesis, dendritic growth, axon growth, and electrophysiology

Parallel feedback pathways in visual cortex of cats revealed through a modified rabies virus

Variability in Neuron Densities across the Cortical Sheet in Primates

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