Physiological differences between neurons in layer 2 and layer 3 of primary visual cortex (V1) of alert macaque monkeys

Gur, Moshe; Snodderly, D. Max

doi:10.1113/jphysiol.2008.151795

Cited by 34 publications

(34 citation statements)

References 62 publications

(103 reference statements)

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“…Basal dendrites of layer 3 pyramidal cells receive the cell's feedforward input via layer 4 from the few compact sources that specify the cell's selective sensitivity (Markov et al, 2014). In contrast to that the diverse inputs to pyramidal cell tufts include direct feedback from higher cortical regions, indirect feedback via the thalamus, and long-range lateral connections both within and between cortical regions (Gur & Snodderly, 2008;Rubio-Garrido, Perez-de-Manzo, Porrero, Galazo, & Clasca, 2009). About 90% of the synaptic inputs to layer 1 come from long-range connections, with only about 10% coming from nearby neurons.…”

Section: Apical Tufts In Layer 1 Of Neocortex Receive Inputs From DIVmentioning

confidence: 96%

“…Furthermore, the tufts of neurons in layers 2, 3 and 5 are intermingled in layer 1, suggesting that they may share a common amplifying input. Another difficulty is that the evidence for AA shows clearly that input to the apical tufts comes from a diverse range of sources and is not limited just to feedback from the succeeding hierarchical level (Gur & Snodderly, 2008). As feedback via layer 1 is combined with information from such a diverse variety of other sources it is hard to see how it can determine both what the feedforward signals code for and their strength or precision.…”

Section: The Bayesian Brain Predictive Coding and Free Energy Minimimentioning

confidence: 98%

“…If whatever is fed forward is prediction error, as suggested by Shipp et al (2013) using complex cells in V1 as an example, then AA could provide a mechanism for amplifying prediction error signals, because layer 3 pyramidal cells, which are a major source of inter-regional feedforward signals, have extensive tufts in layer 1 (e.g. Gur & Snodderly, 2008;Petreanu et al, 2009). Note, however, that such evidence does not show that it is useful to describe whatever is fed forward as 'prediction error'.…”

Section: The Bayesian Brain Predictive Coding and Free Energy Minimimentioning

confidence: 99%

“…Outputs from the microcircuits are shown by thinner arrows than inputs to indicate that they compress information selected from their driving inputs. The apical integration sites of the microcircuits are shown as ovals, and inputs to their synapses are shown as arising from diverse sources (see review by Gur & Snodderly, 2008). They guide the selection process via both their effect on on-going processing and by their effect on learning.…”

Section: Inhibitory Regulation Of Apical Amplificationmentioning

confidence: 99%

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Cognitive functions of intracellular mechanisms for contextual amplification

Phillips

2017

Brain and Cognition

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“…However, because of the lack of clearly distinguishing anatomical features under most experimental conditions, L2 and L3 were treated as one layer (L2/3) in most physiological studies (e.g., 8,10,11,[42][43][44][45]. Recently, evidence for functional differences in electrical activity between L2 and L3 has accumulated from different cortical areas, such as somatosensory barrel cortex (2,46,47) and visual cortex (48). Here, we report data that provide a quantitative basis for a clear anatomical separation of L2 and L3 based on the distribution of the cell bodies of inhibitory neurons.…”

Section: Molecular Markers Of Ins In a Corticalmentioning

confidence: 99%

Inhibitory interneurons in a cortical column form hot zones of inhibition in layers 2 and 5A

Meyer

Schwarz

Wimmer

et al. 2011

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

189

158

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Although physiological data on microcircuits involving a few inhibitory neurons in the mammalian cerebral cortex are available, data on the quantitative relation between inhibition and excitation in cortical circuits involving thousands of neurons are largely missing. Because the distribution of neurons is very inhomogeneous in the cerebral cortex, it is critical to map all neurons in a given volume rather than to rely on sparse sampling methods. Here, we report the comprehensive mapping of interneurons (INs) in cortical columns of rat somatosensory cortex, immunolabeled for neuron-specific nuclear protein and glutamate decarboxylase. We found that a column contains ∼2,200 INs (11.5% of ∼19,000 neurons), almost a factor of 2 less than previously estimated. The density of GABAergic neurons was inhomogeneous between layers, with peaks in the upper third of L2/3 and in L5A. IN density therefore defines a distinct layer 2 in the sensory neocortex. In addition, immunohistochemical markers of IN subtypes were layer-specific. The "hot zones" of inhibition in L2 and L5A match the reported low stimulus-evoked spiking rates of excitatory neurons in these layers, suggesting that these inhibitory hot zones substantially suppress activity in the neocortex.F or a quantitative understanding of the interaction between excitatory and inhibitory synaptic transmission in the neocortex, it is crucial to obtain data on the absolute numbers and the relative distribution of excitatory and inhibitory (mostly GABAergic) neurons [interneurons (INs)] in a cortical column. Only on the basis of such prevalence numbers is it possible to interpret data on single-cell physiology (1-8) and synaptic connections of pairs of neurons (9-12) at the circuit level. The distribution of cortical neurons and INs has therefore been the objective of several studies over the past decades (13-15). Statistical sampling methods were used because mapping tens of thousands of neurons was not feasible. Although the nominal error bounds of such methods are in the range of 10-20%, the reported absolute numbers differed strongly among studies, especially for sparse neuron populations, such as INs and their subtypes. The ratio of INs reported for the somatosensory cortex varied between 15% and 25%, thus by almost a factor of 2 (13,16,17). Data on possible differences in IN density between layers in a cortical column were contradictory (13,15,16,18,19).To resolve these substantial discrepancies, we undertook the complete mapping of INs in entire cortical columns using the cytoarchitectonic barrels in L4 as a reference frame for the thalamocortical innervation volume (20) in postnatal day (P) 25-36 rat vibrissal cortex. Our data show that the overall prevalence of inhibitory neurons was previously overestimated by almost a factor of 2. We find a unique substructure of the distribution of INs in a cortical column that can explain the layer-specific differences in the excitability in neocortex. The distribution of INs defines layer 2 as a distinct neocortical layer.

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Physiological differences between neurons in layer 2 and layer 3 of primary visual cortex (V1) of alert macaque monkeys

Cited by 34 publications

References 62 publications

Cognitive functions of intracellular mechanisms for contextual amplification

Inhibitory interneurons in a cortical column form hot zones of inhibition in layers 2 and 5A

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