How does the cerebral cortex work? Learning, attention, and grouping by the laminar circuits of visual cortex

Abstract Using stereological analysis of NeuN-stained sections, we investigated neuronal density and number of neurons per column throughout the marmoset cortex. Estimates of mean neuronal density encompassed a greater than 3-fold range, from >150 000 neurons/mm3 in the primary visual cortex to ~50 000 neurons/mm3 in the piriform complex. There was a trend for density to decrease from posterior to anterior cortex, but also local gradients, which resulted in a complex pattern; for example, in frontal, auditory, and somatosensory cortex neuronal density tended to increase towards anterior areas. Anterior cingulate, motor, premotor, insular, and ventral temporal areas were characterized by relatively low neuronal densities. Analysis across the depth of the cortex revealed greater laminar variation of neuronal density in occipital, parietal, and inferior temporal areas, in comparison with other regions. Moreover, differences between areas were more pronounced in the supragranular layers than in infragranular layers. Calculations of the number of neurons per unit column revealed a pattern that was distinct from that of neuronal density, including local peaks in the posterior parietal, superior temporal, precuneate, frontopolar, and temporopolar regions. These results suggest that neuronal distribution in adult cortex result from a complex interaction of developmental/ evolutionary determinants and functional requirements.

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Perceptual detection depends on spike count integration

10.1101/865410 ◽

2019 ◽

Author(s):

Jackson J. Cone ◽

Morgan L. Bade ◽

Nicolas Y. Masse ◽

Elizabeth A. Page ◽

David J. Freedman ◽

...

Keyword(s):

Neural Networks ◽

Cerebral Cortex ◽

Visual Cortex ◽

Recurrent Neural Networks ◽

Neural Circuit ◽

Visual Detection ◽

Spike Count ◽

Neuronal Responses ◽

Neuronal Populations ◽

And Behavior

AbstractWhenever the retinal image changes some neurons in visual cortex increase their rate of firing, while others decrease their rate of firing. Linking specific sets of neuronal responses with perception and behavior is essential for understanding mechanisms of neural circuit computation. We trained mice to perform visual detection tasks and used optogenetic perturbations to increase or decrease neuronal spiking primary visual cortex (V1). Perceptual reports were always enhanced by increments in V1 spike counts and impaired by decrements, even when increments and decrements were delivered to the same neuronal populations. Moreover, detecting changes in cortical activity depended on spike count integration rather than instantaneous changes in spiking. Recurrent neural networks trained in the task similarly relied on increments in neuronal activity when activity was costly. This work clarifies neuronal decoding strategies employed by cerebral cortex to translate cortical spiking into percepts that can be used to guide behavior.

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Cortex: Topography and Organization

10.1093/med/9780197512166.003.0021 ◽

2021 ◽

pp. 175-178

Author(s):

Richard J. Caselli ◽

David T. Jones

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Gray Matter ◽

Striate Cortex ◽

Neuronal Cell ◽

Area 17 ◽

Neuronal Cell Bodies ◽

Brodmann Areas ◽

Functional Components ◽

Complex Activities

The cerebral cortex is involved in various simple and complex activities. It consists of layers of neuronal cell bodies (ie, gray matter) that are organized into gyri (convolutions).The cortex can be divided into functional components in several ways. Various schemes are based on function, cytoarchitecture, topography, or Brodmann areas. The terminology can be confusing because the same area of cortex could be designated by several names. For instance, Brodmann area 17 is also called the primary visual cortex, the striate cortex, and the calcarine cortex. Brodmann designated 52 regions of the cerebral cortex according to cytoarchitecture.

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The Effect of Attention on Neuronal Responses to High and Low Contrast Stimuli

Journal of Neurophysiology ◽

10.1152/jn.01019.2009 ◽

2010 ◽

Vol 104 (2) ◽

pp. 960-971 ◽

Cited By ~ 24

Author(s):

Joonyeol Lee ◽

John H. R. Maunsell

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Rhesus Monkeys ◽

Receptive Fields ◽

Visual Area ◽

Neuronal Responses ◽

Attentional Modulation ◽

Low Contrast ◽

Middle Temporal ◽

Visual Area Mt

It remains unclear how attention affects the tuning of individual neurons in visual cerebral cortex. Some observations suggest that attention preferentially enhances responses to low contrast stimuli, whereas others suggest that attention proportionally affects responses to all stimuli. Resolving how attention affects responses to different stimuli is essential for understanding the mechanism by which it acts. To explore the effects of attention on stimuli of different contrasts, we recorded from individual neurons in the middle temporal visual area (MT) of rhesus monkeys while shifting their attention between preferred and nonpreferred stimuli within their receptive fields. This configuration results in robust attentional modulation that makes it possible to readily distinguish whether attention acts preferentially on low contrast stimuli. We found no evidence for greater enhancement of low contrast stimuli. Instead, the strong attentional modulations were well explained by a model in which attention proportionally enhances responses to stimuli of all contrasts. These data, together with observations on the effects of attention on responses to other stimulus dimensions, suggest that the primary effect of attention in visual cortex may be to simply increase the strength of responses to all stimuli by the same proportion.

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A collicular visual cortex: Neocortical space for an ancient midbrain visual structure

Science ◽

10.1126/science.aau7052 ◽

2019 ◽

Vol 363 (6422) ◽

pp. 64-69 ◽

Cited By ~ 54

Author(s):

Riccardo Beltramo ◽

Massimo Scanziani

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Primary Visual Cortex ◽

Visual Information ◽

Cortical Area ◽

Moving Objects ◽

Visual Responses ◽

Visual Cortical Area ◽

Postrhinal Cortex ◽

Visual Cortical

Visual responses in the cerebral cortex are believed to rely on the geniculate input to the primary visual cortex (V1). Indeed, V1 lesions substantially reduce visual responses throughout the cortex. Visual information enters the cortex also through the superior colliculus (SC), but the function of this input on visual responses in the cortex is less clear. SC lesions affect cortical visual responses less than V1 lesions, and no visual cortical area appears to entirely rely on SC inputs. We show that visual responses in a mouse lateral visual cortical area called the postrhinal cortex are independent of V1 and are abolished upon silencing of the SC. This area outperforms V1 in discriminating moving objects. We thus identify a collicular primary visual cortex that is independent of the geniculo-cortical pathway and is capable of motion discrimination.

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Changing patterns of synaptic input to subplate and cortical plate during development of visual cortex

Journal of Neurophysiology ◽

10.1152/jn.1991.66.6.2059 ◽

1991 ◽

Vol 66 (6) ◽

pp. 2059-2071 ◽

Cited By ~ 105

Author(s):

E. Friauf ◽

C. J. Shatz

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Synaptic Input ◽

Field Potential ◽

Short Latency ◽

Cortical Plate ◽

Synaptic Activation ◽

Cortical Layers ◽

Subplate Neurons ◽

Monosynaptic Excitation

1. The development of excitatory activation in the visual cortex was studied in fetal and neonatal cats. During fetal and neonatal life, the immature cerebral cortex (the cortical plate) is sandwiched between two synaptic zones: the marginal zone above, and an area just below the cortical plate, the subplate. The subplate is transient and disappears by approximately 2 mo postnatal. Here we have investigated whether the subplate and the cortical plate receive functional synaptic inputs in the fetus, and when the adultlike pattern of excitatory synaptic input to the cortical plate appears during development. 2. Extracellular field potential recording to electrical stimulation of the optic radiation was performed in slices of cerebral cortex maintained in vitro. Laminar profiles of field potentials were converted by the current-source density (CSD) method to identify the spatial and temporal distribution of neuronal excitation within the subplate and the cortical plate. 3. Between embryonic day 47 (E47) and postnatal day 28 (P28; birth, E65), age-related changes occur in the pattern of synaptic activation of neurons in the cortical plate and the subplate. Early in development, at E47, E57, and P0, short-latency (probably monosynaptic) excitation is most obvious in the subplate, and longer latency (presumably polysynaptic) excitation can be seen in the cortical plate. Synaptic excitation in the subplate is no longer apparent at P21 and P28, a time when cell migration is finally complete and the cortical layers have formed. By contrast, excitation in the cortical plate is prominent in postnatal animals, and the temporal and spatial pattern has changed. 4. The adultlike sequence of synaptic activation in the different cortical layers can be seen by P28. It differs from earlier ages in several respects. First, short-latency (probably monosynaptic) excitation can be detected in cortical layer 4. Second, multisynaptic, long-lasting activation is present in layers 2/3 and 5. 5. Our results show that the subplate zone, known from anatomic studies to be a synaptic neurophil during development, receives functional excitatory inputs from axons that course in the developing white matter. Because the only mature neurons present in this zone are the subplate neurons, we conclude that subplate neurons are the principal, if not the exclusive, recipients of this input. The results suggest further that the excitation in the subplate in turn is relayed to neurons of the cortical plate via axon collaterals of subplate neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

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Cerebral Cortex, Vol. 3, Visual Cortex

Neuroscience ◽

10.1016/0306-4522(86)90314-3 ◽

1986 ◽

Vol 19 (3) ◽

pp. 1023

Author(s):

A. Cowey

Keyword(s):

Cerebral Cortex ◽

Visual Cortex

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Tms in Migraine

10.1093/oxfordhb/9780198568926.013.0024 ◽

2012 ◽

Author(s):

Jean Schoenen ◽

Valentin Bohotin ◽

Alain Maertens De Noordhout

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Event Related Potential ◽

Visual Cortices ◽

Multidisciplinary Studies ◽

Migraine Pathophysiology ◽

Cortical Dysfunction

Transcranial magnetic stimulation (TMS) has been used to search for cortical dysfunction in migraine. Both, the motor and the visual cortices have been explored in this area. This article reviews and discusses the results of the various studies performed in migraine patients with TMS of motor or visual cortices. The majority of evoked and event-related potential studies in migraine have shown two abnormalities: increased amplitude of grand averaged responses and lack of habituation in successive blocks of averaged responses with decreased amplitude in the first block. These abnormalities suggest that the excitability state of the cerebral cortex, particularly of the visual cortex, is abnormal in migraineurs between attacks. The use of TMS to assess motor and visual cortex excitability has yielded conflicting results, which could be due to methodological differences. Taken together, all studies indicate that the changes in cortical reactivity are more complex in migraineurs than initially thought and suggest that both larger multidisciplinary studies and focused analyses of subgroups of patients with more refined clinical phenotypes are necessary to disentangle the role of the cerebral cortex in migraine pathophysiology.

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