Degradation of stimulus selectivity of visual cortical cells in senescent rhesus monkeys

Schmolesky, Matthew; Wang, Youngchang; Pu, Mingliang; Leventhal, Audie G.

doi:10.1038/73957

Cited by 319 publications

(305 citation statements)

References 43 publications

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“…A related possibility is that compromised sensory processing is likely to result in decreased selectivity but not necessarily decreased activity. This effect has been observed in the primary visual cortex in aging monkeys (Schmolesky et al 2000). Degraded selectivity (specification of cell response) in these studies was accompanied by increased cell excitability and increased spontaneous activity.…”

supporting

confidence: 64%

“…A number of studies have suggested that there are age-related decreases in attention modulated neural specificity -most commonly observed as a decreased efficiency in the inhibition of unattended or less relevant information. Single cell recordings in senescent monkeys have shown significant reduction in selectivity of neurons in primary visual cortex that may reflect degradation of cortical inhibitory processes (Schmolesky et al 2000). In humans, scalp recorded event-related potential (ERP) studies have reported age-related changes in the amplitude, latency and topographic distribution of brain electrical responses, some of which are consistent with a decreased ability to selectively filter incoming information (review: Polich 1996).…”

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confidence: 99%

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Changing channels: An fMRI study of aging and cross-modal attention shifts

2006

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Age-related deficits in visual selective attention suggest that the efficiency of inhibitory processes is particularly affected by aging. To investigate whether processing inefficiencies observed in visual attention are similar in auditory attention and when shifting attention across modalities, we conducted an FMRI study with healthy young and older adults using a task that required sustained auditory and visual selective attention and cross-modal attention shifts. Older adults in this study performed as well as the younger adults, but showed age-related differences in BOLD responses. The most striking of these differences were bilateral frontal and parietal regions of significantly increased activation in older adults during both focused and shifting attention. Our data suggest that this increased activation did not reflect new recruitment, but reliance on brain regions typically used by younger adults when task demands are greater. Older adults' activation patterns suggested that even during focused attention conditions they were "shifting" attention to stimuli in the unattended modality. Increased activation during processing of both task-relevant and task-irrelevant information implies age-related loss of processing selectivity. These patterns may reflect both task-specific compensatory neural recruitment and degradation of sensory inhibition. 2Selective attention modulates sensory response to enhance selected relative to non-selected information. Electrophysiological studies have shown that the neural response in visual cortex is increased when visual information is attended (Heinze et al. 1994;Hillyard et al. 1998;Mangun et al. 1998). However, attention driven modulation of sensory cortex is not simple signal enhancement (gain), but also reflects neural specificity for the attended information that results from some combination of augmentation of selected and inhibition of non-selected or less relevant stimulation (Murray and Wojciulik 2004).While selective attention may remain grossly intact with normal aging, some components of attentional processing are affected. Hasher and Zacks (Hasher and Zacks 1988) proposed a model in which age-related deficits in attentional selectivity underlie changes in memory function. They suggested that an ineffective inhibitory system would allow irrelevant information into working memory buffers resulting in the association of large numbers of less specific memory traces. Additionally, an inefficient inhibitory system would affect the ability to suppress irrelevant pathways during memory retrieval and may reflect a central mechanism underlying both distractibility and memory deficits in older adults. A number of studies have suggested that there are age-related decreases in attention modulated neural specificity -most commonly observed as a decreased efficiency in the inhibition of unattended or less relevant information. Single cell recordings in senescent monkeys have shown significant reduction in selectivity of neurons in primary visual cortex that may reflect...

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confidence: 64%

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confidence: 99%

Changing channels: An fMRI study of aging and cross-modal attention shifts

2006

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“…Previous studies dealing with age-related changes in the mammalian visual system have concluded that these are primarily cortical in nature (5,(34)(35)(36). Moreover, these studies emphasized the debilitating effects of the age-related changes, in particular the loss of orientation selectivity by cortical neurons, which appears to reflect a decrease in GABA-dependent neural communication (37).…”

Section: Discussionmentioning

confidence: 99%

Dendrites of rod bipolar cells sprout in normal aging retina

Liets

Eliasieh

List

et al. 2006

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

102

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The aging nervous system is known to manifest a variety of degenerative and regressive events. Here we report the unexpected growth of dendrites in the retinas of normal old mice. The dendrites of many rod bipolar cells in aging mice were observed to extend well beyond their normal strata within the outer plexiform layer to innervate the outer nuclear layer where they appeared to form contacts with the spherules of rod photoreceptors. Such dendritic sprouting increased with age and was evident at all retinal eccentricities. These results provide evidence of retinal plasticity associated with normal aging.plasticity ͉ senescence ͉ visual system

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“…Recent work by Leventhal and colleagues (26,30) in normal aging monkeys reports physiological evidence of age-related changes in microcolumnar function including disruption of orientation selectivity, a property of the microcolumn in visual cortex. These changes may reflect a functional disruption of the microcolumn in normal aging, perhaps due to factors similar to those cited above that lead to subtle neuron displacements of sufficient magnitude to produce our observed change in S. It is important to note that the age-related decrease in S occurs in layer III of area 46 because the pyramidal cells of this layer give rise to ipsilateral and contralateral cortico-cortical connections.…”

Section: Mechanisms Of Change In Microcolumnarmentioning

confidence: 99%

Age-related reduction in microcolumnar structure in area 46 of the rhesus monkey correlates with behavioral decline

Cruz

Roe

Urbanc

et al. 2004

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

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Many age-related declines in cognitive function are attributed to the prefrontal cortex, area 46 being especially critical. Yet in normal aging, studies indicate that neurons are not lost in area 46, suggesting that impairments result from more subtle processes. One cortical feature that is functionally important, but that has not been examined in normal aging because of a lack of efficient quantitative methods, is the vertical arrangement of neurons into microcolumns, a fundamental computational unit of the cortex. By using a density-map method derived from condensed-matter physics, we quantified microcolumns in area 46 of seven young and seven aged rhesus monkeys that had been cognitively tested. This analysis demonstrated that there is no age-related reduction in total neuronal density or in microcolumn width, length, or periodicity. There was, however, a statistically significant decrease in the strength of microcolumns, indicating microcolumnar disorganization. This reduction in strength was significantly correlated with age-related cognitive decline on tests of spatial working memory and recognition memory independent of the effect of age. Modeling demonstrated that random neuron displacements of Ϸ30% of a neuronal diameter (<3 m) produced the observed reduction in strength. Hence, it is possible that, with changes in dendrites and myelinated axons, subtle displacements of neurons occur that alter microcolumnar structure and correlate with ageinduced dysfunction. Therefore, quantitative measurement of microcolumnar structure may provide a sensitive morphological method to assay microcolumnar function in aging and other conditions. minicolumns ͉ density map ͉ cerebral cortex ͉ primate brain ͉ modeling

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Degradation of stimulus selectivity of visual cortical cells in senescent rhesus monkeys

Cited by 319 publications

References 43 publications

Changing channels: An fMRI study of aging and cross-modal attention shifts

Changing channels: An fMRI study of aging and cross-modal attention shifts

Dendrites of rod bipolar cells sprout in normal aging retina

Age-related reduction in microcolumnar structure in area 46 of the rhesus monkey correlates with behavioral decline

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