Man's Triune Conscious Mind: Part III

1995 ◽  
Vol 81 (2) ◽  
pp. 463-466
Author(s):  
Carl G. Aurell
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Conscious Mind ◽  
Perceptual Model ◽  
Cortex Area ◽  
Layer 4

The perceptual model, discussed previously in Part II, is applied to the organization of the visual cortex in a search for “consciousness neurons,” i.e., sources of sensations, images, and percepts. It is hypothesized that these three conscious phenomena emerge in the primary visual cortex, Area VI, possibly from neurons in its Layer 4.

scholarly journals Layer 4 in Primary Visual Cortex of the Awake Rabbit: Contrasting Properties of Simple Cells and Putative Feedforward Inhibitory Interneurons

2013 ◽  
Vol 33 (28) ◽  
pp. 11372-11389 ◽  
Author(s):  
J. Zhuang ◽  
C. R. Stoelzel ◽  
Y. Bereshpolova ◽  
J. M. Huff ◽  
X. Hei ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Inhibitory Interneurons ◽  
Simple Cells ◽  
Layer 4

Map of the synapses onto layer 4 basket cells of the primary visual cortex of the cat

1997 ◽  
Vol 380 (2) ◽  
pp. 230-242 ◽  
Author(s):  
Bashir Ahmed ◽  
John C. Anderson ◽  
Kevan A.C. Martin ◽  
J. Charmaine Nelson
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Basket Cells ◽  
Layer 4

Neural responses to relative speed in the primary visual cortex of rhesus monkey

2003 ◽  
Vol 20 (1) ◽  
pp. 77-84 ◽  
Author(s):  
AN CAO ◽  
PETER H. SCHILLER
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Relative Motion ◽  
Motion Parallax ◽  
Relative Speed ◽  
Neural Responses ◽  
Tuning Curves ◽  
V1 Neurons ◽  
Cortex Area ◽  
Ground Segmentation

Relative motion information, especially relative speed between different input patterns, is required for solving many complex tasks of the visual system, such as depth perception by motion parallax and motion-induced figure/ground segmentation. However, little is known about the neural substrate for processing relative speed information. To explore the neural mechanisms for relative speed, we recorded single-unit responses to relative motion in the primary visual cortex (area V1) of rhesus monkeys while presenting sets of random-dot arrays moving at different speeds. We found that most V1 neurons were sensitive to the existence of a discontinuity in speed, that is, they showed higher responses when relative motion was presented compared to homogenous field motion. Seventy percent of the neurons in our sample responded predominantly to relative rather than to absolute speed. Relative speed tuning curves were similar at different center–surround velocity combinations. These relative motion-sensitive neurons in macaque area V1 probably contribute to figure/ground segmentation and motion discontinuity detection.

scholarly journals Vision reconstructs the cellular composition of binocular circuitry during the critical period

2020 ◽  
Author(s):  
Liming Tan ◽  
Elaine Tring ◽  
Dario L. Ringach ◽  
S. Lawrence Zipursky ◽  
Joshua T. Trachtenberg
Keyword(s):  
Visual Cortex ◽  
Receptive Field ◽  
Primary Visual Cortex ◽  
Critical Period ◽  
Cellular Composition ◽  
Feature Detectors ◽  
Layer 2 ◽  
Layer 4 ◽  
High Acuity ◽  
Longitudinal Imaging

AbstractHigh acuity binocularity is established in primary visual cortex during an early postnatal critical period. In contrast to current models for the developmental of binocular neurons, we find that the binocular network present at the onset of the critical period is dismantled and remade. Using longitudinal imaging of receptive field tuning (e.g. orientation selectivity) of thousands of layer 2/3 neurons through development, we show most binocular neurons present at critical-period onset are poorly tuned and rendered monocular. These are replenished by newly formed binocular neurons that are established by a vision-dependent recruitment of well-tuned ipsilateral inputs to contralateral monocular neurons with matched tuning properties. The binocular network in layer 4 is equally unstable but does not improve. Thus, vision instructs a new and more sharply tuned binocular network in layer 2/3 by exchanging one population of neurons for another and not by refining an extant network.One Sentence SummaryUnstable binocular circuitry is transformed by vision into a network of highly tuned complex feature detectors in the cortex.

Numerical relationship between neurons in the lateral geniculate nucleus and primary visual cortex in macaque monkeys

1996 ◽  
Vol 13 (3) ◽  
pp. 585-590 ◽  
Author(s):  
Ivan Suner ◽  
Pasko Rakic
Keyword(s):  
Visual Cortex ◽  
Lateral Geniculate Nucleus ◽  
Primary Visual Cortex ◽  
Rhesus Monkeys ◽  
Three Dimensional ◽  
Area 17 ◽  
Counting Method ◽  
Lateral Geniculate ◽  
Cortex Area ◽  
The Right

AbstractWe examined the numerical correlation between total populations of neurons in the lateral geniculate nucleus (LGN) and the primary visual cortex (area 17 of Brodmann) in ten cerebral hemispheres of five normal rhesus monkeys using an unbiased three-dimensional counting method. There were 1.4 ± 0.2 million and 341 ±54 million neurons in the LGN and area 17, respectively. In each animal, a larger LGN on one side was in register with a larger area 17 of the cortex on the same side. Furthermore, asymmetry in the number of neurons in both the LGN and area 17 favored the right side. However, because of small variations across subjects, correlation between the total neuron number in LGN and area 17 was weak (r = 0.29). These results suggest that the final numbers of neurons in these visual centers may be established independently or by multiple factors controlling elimination of initially overproduced neurons.

scholarly journals Long-wavelength (reddish) hues induce unusually large gamma oscillations in the primate primary visual cortex

2018 ◽  
Vol 115 (17) ◽  
pp. 4489-4494 ◽  
Author(s):  
Vinay Shirhatti ◽  
Supratim Ray
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Gamma Oscillations ◽  
Full Field ◽  
Long Wavelength ◽  
Natural Vision ◽  
Cortex Area ◽  
Electrophysiological Signals ◽  
Size Contrast ◽  
Highly Correlated

Gamma oscillations (∼30–80 Hz) are a prominent signature of electrophysiological signals, with a purported role in natural vision. Previous studies in the primary visual cortex (area V1) have shown that achromatic gratings or gabor stimuli generate salient gamma oscillations, whose strength and frequency depend on stimulus properties such as their size, contrast, and orientation. Surprisingly, although natural images are rarely achromatic, the effect of chromatic input on gamma has not been thoroughly investigated. Recording from primate V1, we show that gamma oscillations of extremely high magnitude (peak increase of ∼300-fold in some cases), far exceeding the gamma generated by optimally tuned achromatic gratings, are induced in the local field potentials by full-field color stimuli of different hues. Furthermore, gamma oscillations are sensitive to the hue of the chromatic input, with the strongest oscillations for long-wavelength (reddish) hues and another, smaller gamma response peak for hues in the short-wavelength (bluish) range, which lie approximately on the two cardinal chromatic response axes of the upstream lateral geniculate nucleus neurons. These oscillations depended critically on the purity of the hue, decreasing with hue desaturation, but remained robust for pure hue stimuli even at reduced luminance. Importantly, the magnitude of gamma oscillations was highly correlated with positive L−M cone contrast produced by the stimuli, suggesting that gamma could be a marker of the specific mechanisms underlying this computation. These findings provide insights into the generation of gamma oscillations, as well as the processing of color along the visual pathway.

Orientation topography of layer 4 lateral networks revealed by optical imaging in cat visual cortex (area 18)

1999 ◽  
Vol 11 (12) ◽  
pp. 4291-4308 ◽  
Author(s):  
Tagrid Yousef ◽  
Tobias Bonhoeffer ◽  
Dae-Shik Kim ◽  
Ulf T. Eysel ◽  
Éva Tóth ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Optical Imaging ◽  
Area 18 ◽  
Cat Visual Cortex ◽  
Cortex Area ◽  
Layer 4

Age-Dependent Decline in Supragranular Long-Term Synaptic Plasticity by Increased Inhibition During the Critical Period in the Rat Primary Visual Cortex

2009 ◽  
Vol 101 (1) ◽  
pp. 269-275 ◽  
Author(s):  
Hyun-Jong Jang ◽  
Kwang-Hyun Cho ◽  
Hyun-Sok Kim ◽  
Sang June Hahn ◽  
Myung-Suk Kim ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Critical Period ◽  
Excitatory Postsynaptic Potential ◽  
Age Dependent ◽  
Layer 4 ◽  
Old Rats ◽  
Synaptic Model

Supragranular long-term potentiation (LTP) and depression (LTD) are continuously induced in the pathway from layer 4 during the critical period in the rodent primary visual cortex, which limits the use of supragranular long-term synaptic plasticity as a synaptic model for the mechanism of ocular dominance (OD) plasticity. The results of the present study demonstrate that the pulse duration of extracellular stimulation to evoke a field potential (FP) is critical to induction of LTP and LTD in this pathway. LTP and LTD were induced in the pathway from layer 4 to layer 2/3 in slices from 3-wk-old rats when FPs were evoked by 0.1- and 0.2-ms pulses. LTP and LTD were induced in slices from 5-wk-old rats when evoked by stimulation with a 0.2-ms pulse but not by stimulation with a 0.1-ms pulse. Both the inhibitory component of FP and the inhibitory/excitatory postsynaptic potential amplitude ratio evoked by stimulation with a 0.1-ms pulse were greater than the values elicited by a 0.2-ms pulse. Stimulation with a 0.1-ms pulse at various intensities that showed the similar inhibitory FP component with the 0.2-ms pulse induced both LTD and LTP in 5-wk-old rats. Thus extracellular stimulation with shorter-duration pulses at higher intensity resulted in greater inhibition than that observed with longer-duration pulses at low intensity. This increased inhibition might be involved in the age-dependent decline of synaptic plasticity during the critical period. These results provide an alternative synaptic model for the mechanism of OD plasticity.

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