Dynamics of orientation coding in area V1 of the awake primate

1993 ◽  
Vol 10 (5) ◽  
pp. 811-825 ◽  
Author(s):  
Simona Celebrini ◽  
Simon Thorpe ◽  
Yves Trotter ◽  
Michel Imbert
Keyword(s):  
Visual Information ◽  
Cortical Area ◽  
Neuronal Response ◽  
Mean Value ◽  
Feedback Loops ◽  
Orientation Selectivity ◽  
Orientation Tuning ◽  
Neuronal Responses ◽  
Half Height ◽  
Marked Tendency

AbstractTo investigate the importance of feedback loops in visual information processing, we have analyzed the dynamic aspects of neuronal responses to oriented gratings in cortical area V1 of the awake primate. If recurrent feedback is important in generating orientation selectivity, the initial part of the neuronal response should be relatively poorly selective, and full orientation selectivity should only appear after a delay. Thus, by examining the dynamics of the neuronal responses it should be possible to assess the importance of feedback processes in the development of orientation selectivity. The results were base on a sample of 259 cells recorded in two monkeys, of which 89% were visually responsive. Of these, approximately two-thirds were orientation selective. Response latency varied considerably between neurons, ranging from a minimum of 41 ms to over 150 ms, although most had latencies of 50–70 ms. Orientation tuning (defined as the bandwidth at half-height) ranged from 16 deg to over 90 deg, with a mean value of around 55 deg. By examining the selectivity of these different neurons by 10-ms time slices, starting at the onset of the neuronal response, we found that the orientation selectivity of virtually every neuron was fully developed at the very start of the neuronal response. Indeed, many neurons showed a marked tendency to respond at somewhat longer latencies to stimuli that were nonoptimally oriented, with the result that orientation selectivity was highest at the very start of the neuronal response. Furthermore, there was no evidence that the neurons with the shortest onset latencies were less selective. Such evidence is inconsistent with the hypothesis that recurrent intracortical feedback plays an important role in the generation of orientation selectivity. Instead, we suggest that orientation selectivity is primarily generated using feedforward mechanisms, including feedforward inhibition. Such a strategy has the advantage of allowing orientation to be computed rapidly, and avoids the initially poorly selective neuronal responses that characterize processing involving recurrent loops.

scholarly journals The Neurophysiology of Backward Visual Masking: Information Analysis

1999 ◽  
Vol 11 (3) ◽  
pp. 300-311 ◽  
Author(s):  
Edmund T. Rolls ◽  
Martin J. Tovée ◽  
Stefano Panzeri
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
Computational Models ◽  
Direct Evidence ◽  
Visual Masking ◽  
Neuronal Response ◽  
Short Soas ◽  
Stimulus Onset ◽  
Backward Masking ◽  
Neuronal Responses

Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in firing rate because it is the selective part of the firing that is especially attenuated by the mask, not the spontaneous firing, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500-msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates.

scholarly journals Hand placement near the visual stimulus improves orientation selectivity in V2 neurons

2015 ◽  
Vol 113 (7) ◽  
pp. 2859-2870 ◽  
Author(s):  
Carolyn J. Perry ◽  
Lauren E. Sergio ◽  
J. Douglas Crawford ◽  
Mazyar Fallah
Keyword(s):  
Visual Processing ◽  
Neuronal Response ◽  
Oculomotor System ◽  
Orientation Selectivity ◽  
Orientation Tuning ◽  
Area V2 ◽  
Visual Enhancement ◽  
Orthogonal Orientation ◽  
Psychophysical Studies ◽  
The Brain

Often, the brain receives more sensory input than it can process simultaneously. Spatial attention helps overcome this limitation by preferentially processing input from a behaviorally-relevant location. Recent neuropsychological and psychophysical studies suggest that attention is deployed to near-hand space much like how the oculomotor system can deploy attention to an upcoming gaze position. Here we provide the first neuronal evidence that the presence of a nearby hand enhances orientation selectivity in early visual processing area V2. When the hand was placed outside the receptive field, responses to the preferred orientation were significantly enhanced without a corresponding significant increase at the orthogonal orientation. Consequently, there was also a significant sharpening of orientation tuning. In addition, the presence of the hand reduced neuronal response variability. These results indicate that attention is automatically deployed to the space around a hand, improving orientation selectivity. Importantly, this appears to be optimal for motor control of the hand, as opposed to oculomotor mechanisms which enhance responses without sharpening orientation selectivity. Effector-based mechanisms for visual enhancement thus support not only the spatiotemporal dissociation of gaze and reach, but also the optimization of vision for their separate requirements for guiding movements.

Attention to Both Space and Feature Modulates Neuronal Responses in Macaque Area V4

2000 ◽  
Vol 83 (3) ◽  
pp. 1751-1755 ◽  
Author(s):  
Carrie J. McAdams ◽  
John H. R. Maunsell
Keyword(s):  
Rhesus Monkeys ◽  
Cortical Area ◽  
Neuronal Response ◽  
Spatial Location ◽  
Neuronal Responses ◽  
Directed Attention ◽  
Macaque Monkeys ◽  
Area V4 ◽  
Electrophysiological Studies ◽  
Psychological Experiments

Attention is the mechanism with which we select specific aspects of our environment for processing. Psychological experiments have shown that attention can be directed to a spatial location or to a particular object. Electrophysiological studies in trained macaque monkeys have found that attention can strengthen the responses of neurons in cortical area V4. Some of these studies have attributed these effects to spatial attention, whereas others have suggested that feature-directed attention may modulate the neuronal response. Here we report that neuronal correlates for both spatial and feature-directed attention exist in individual neurons in area V4 of behaving rhesus monkeys.

scholarly journals Most Superficial Sublamina of Rat Superior Colliculus: Neuronal Response Properties and Correlates With Perceptual Figure–Ground Segregation

2007 ◽  
Vol 98 (1) ◽  
pp. 161-177 ◽  
Author(s):  
S. V. Girman ◽  
R. D. Lund
Keyword(s):  
Superior Colliculus ◽  
Visual Processing ◽  
Cortical Neurons ◽  
Visual Information ◽  
Complex Analysis ◽  
Complex Dynamics ◽  
Neuronal Response ◽  
Target Selection ◽  
Orientation Tuning ◽  
Early Stages

The uppermost layer (stratum griseum superficiale, SGS) of the superior colliculus (SC) provides an important gateway from the retina to the visual extrastriate and visuomotor systems. The majority of attention has been given to the role of this “visual” SC in saccade generation and target selection and it is generally considered to be less important in visual perception. We have found, however, that in the rat SGS1, the most superficial division of the SGS, the neurons perform very sophisticated analysis of visual information. First, in studying their responses with a variety of flashing stimuli we found that the neurons respond not to brightness changes per se, but to the appearance and/or disappearance of visual shapes in their receptive fields (RFs). Contrary to conventional RFs of neurons at the early stages of visual processing, the RFs in SGS1 cannot be described in terms of fixed spatial distribution of excitatory and inhibitory inputs. Second, SGS1 neurons showed robust orientation tuning to drifting gratings and orientation-specific modulation of the center response from surround. These are features previously seen only in visual cortical neurons and are considered to be involved in “contour” perception and figure–ground segregation. Third, responses of SGS1 neurons showed complex dynamics; typically the response tuning became progressively sharpened with repetitive grating periods. We conclude that SGS1 neurons are involved in considerably more complex analysis of retinal input than was previously thought. SGS1 may participate in early stages of figure–ground segregation and have a role in low-resolution nonconscious vision as encountered after visual decortication.

scholarly journals A9 DORSAL ROOT GANGLIA NEURONAL RESPONSES AND SUBSTANCE P PRODUCTION ARE HIGHER IN MALE MICE

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 10-11
Author(s):  
J Pujo ◽  
G De Palma ◽  
J Lu ◽  
S M Collins ◽  
P Bercik
Keyword(s):  
Abdominal Pain ◽  
Substance P ◽  
Gut Microbiota ◽  
Sensory Neurons ◽  
Dorsal Root ◽  
Neuronal Response ◽  
Neuronal Responses ◽  
Visceral Sensitivity ◽  
Germ Free

Abstract Background Abdominal pain is a common complaint in patients with chronic gastrointestinal disorders. Accumulating evidence suggests that gut microbiota is an important determinant of gut function, including visceral sensitivity. Germ-free (GF) mice have been shown to display visceral hypersensitivity, which normalizes after colonization. Sex also appears to play a key role in visceral sensitivity, as women report more abdominal pain than men. Thus, both gut bacteria and sex are important in the regulation of gut nociception, but the underlying mechanisms remain poorly understood. Aims To investigate the role of gut microbiota and sex in abdominal pain. Methods We used primary cultures of sensory neurons from dorsal root ganglia (DRG) of female and male conventionally raised (SPF) or germ-free (GF) mice (7–18 weeks old). To study the visceral afferent activity in vitro, calcium mobilization in DRG sensory neurons was measured by inverted fluorescence microscope using a fluorescent calcium probe Fluo-4 (1mM). Two parameters were considered i) the percentage of responding neurons ii) the intensity of the neuronal response. First, DRG sensory neurons were stimulated by a TRPV1 agonist capsaicin (12.5nM, 125nM and 1.25µM) or by a mixture of G-protein coupled receptors agonist (GPCR: bradykinin, histamine and serotonin; 1µM, 10µM and 100µM). We next measured the neuronal production of substance P and calcitonin gene-related peptide (CGRP), two neuropeptides associated with nociception, in response to capsaicin (1.25µM) or GPCR agonists (100µM) by ELISA and EIA, respectively. Results The percentage of neurons responding to capsaicin and GPCR agonists was similar in male and female SPF and GF mice. However, the intensity of the neuronal response was higher in SPF male compared to SPF female in response to capsaicin (125nM: p=0.0336; 1.25µM: p=0.033) but not to GPCR agonists. Neuronal activation was similar in GF and SPF mice of both sexes after administration of capsaicin or GPCR agonists. Furthermore, substance P and CGRP production by sensory neurons induced by capsaicin or GPCR agonists was similar in SPF and GF mice, regardless of sex. However, while the response to capsaicin was similar, the GPCR agonists-induced production of substance P was higher in SPF male mice compared to SPF females (p=0.003). The GPCR agonists-induced production of CGRP was similar in SPF male and female mice. Conclusions Our data suggest that at the level of DRG neurons, the absence of gut microbiota does not predispose to visceral hypersensitivity. The intensity of DRG neuronal responses to capsaicin and the GPCR agonists-induced production of substance P are higher in male compared to female mice, in contrast to previously published studies in various models of acute and chronic pain. Further studies are thus needed to investigate the role of sex in visceral sensitivity. Funding Agencies CIHR

Spatio-temporal visual properties in the ascending tectofugal system

2010 ◽  
Vol 5 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Alice Rokszin ◽  
Zita Márkus ◽  
Gábor Braunitzer ◽  
Antal Berényi ◽  
Marek Wypych ◽  
...  
Keyword(s):  
Visual Information ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Neuronal Population ◽  
Neuronal Responses ◽  
Temporal Properties ◽  
Visual Receptive Field ◽  
Detailed Statistical Analysis ◽  
Spatio Temporal ◽  
Visual Properties

AbstractOur study compares the spatio-temporal visual receptive field properties of different subcortical stages of the ascending tectofugal visual system. Extracellular single-cell recordings were performed in the superficial (SCs) and intermediate (SCi) layers of the superior colliculus (SC), the suprageniculate nucleus (Sg) of the posterior thalamus and the caudate nucleus (CN) of halothane-anesthetized cats. Neuronal responses to drifting gratings of various spatial and temporal frequencies were recorded. The neurons of each structure responded optimally to low spatial and high temporal frequencies and displayed narrow spatial and temporal frequency tuning. The detailed statistical analysis revealed that according to its stimulus preferences the SCs has markedly different spatio-temporal properties from the homogeneous group formed by the SCi, Sg and CN. The SCs neurons preferred higher spatial and lower temporal frequencies and had broader spatial tuning than the other structures. In contrast to the SCs the visually active SCi, as well as the Sg and the CN neurons possessed consequently similar spatio-temporal preferences. These data support our hypothesis that the visually active SCi, Sg and CN neurons form a homogeneous neuronal population given a similar spatio-temporal frequency preference and a common function in processing of dynamic visual information.

scholarly journals Neuronal responses in the cortical area MSTd during smooth pursuit and ocular following eye movements

2009 ◽  
Vol 10 (S1) ◽  
Author(s):  
Lukas Brostek ◽  
Seiji Ono ◽  
Michael J Mustari ◽  
Ulrich Nuding ◽  
Ulrich Büttner ◽  
...  
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Cortical Area ◽  
Neuronal Responses ◽  
Ocular Following

scholarly journals Development of the spine following pinealectomy or sensorimotor cortical area damage

2013 ◽  
Vol 82 (4) ◽  
pp. 411-414
Author(s):  
Richard Chaloupka ◽  
Milan Dvořák ◽  
František Tichý ◽  
Jiří Veselý ◽  
Alois Nečas
Keyword(s):  
Cortical Area ◽  
Mean Value ◽  
Albino Rats ◽  
Sham Operation ◽  
Growing Rats ◽  
Growing Rat ◽  
Group 2 ◽  
Wistar Albino Rats ◽  
New Hypothesis ◽  
Group 1

The aim of this experimental study was to assess the spine development in growing rats following pinealectomy or partial sensorimotor cortical area damage. A total of 68 Wistar albino rats (Rattus norvegicus v. alba f. domestica) aged 3–4 weeks were divided into four groups. In group 1 (n = 22) pinealectomy was performed, in group 2 (n = 24) the sensorymotor cortical area 2 × 1 × 1 mm below the coronal suture was removed. Sham operation consisted of a craniotomy (n = 11) and a craniotomy with a durotomy (n = 11). All surgeries were performed from the left side. The rats were killed four months after surgery and radiography was then made. Scoliosis, C2-T7 lordosis and T7-S1 kyphosis were measured.The brains of rats after sensorimotor cortical area removal were isolated and investigated including histological examination (light microscope). Scoliosis of 9–14 degrees (mean value 10.8) was developed in five animals after pinealectomy; in rats after removal of the sensorimotor cortical area scoliosis of 10–24 degrees (mean value 15.9) was observed in eight animals. The scoliotic curves were non structural. Our results indicate the importance of cortical area damage, together with craniotomy and durotomy in the development of growing rat spine. These damages could cause a disorder of balance between smaller inhibitory and greater facilitating area of central nervous system, controlling the muscular tone and resulting in the development of increased lordosis and kyphosis and non structural scoliosis due to muscle imbalance. Thus the new hypothesis of scoliosis aetiology was introduced.

Responses to Moving Visual Stimuli in Pretectal Neurons of the Small-Spotted Dogfish (Scyliorhinus canicula)

2008 ◽  
Vol 99 (1) ◽  
pp. 200-207 ◽  
Author(s):  
Olivia Andrea Masseck ◽  
Klaus-Peter Hoffmann
Keyword(s):  
Visual Information ◽  
Visual Stimulation ◽  
Semicircular Canals ◽  
Neuronal Responses ◽  
Vertical Movements ◽  
Scyliorhinus Canicula ◽  
Random Dot Patterns ◽  
Pretectal Area ◽  
Corpus Geniculatum Laterale ◽  
Sensitive Direction

Single-unit recordings were performed from a retinorecipient pretectal area (corpus geniculatum laterale) in Scyliorhinus canicula. The function and homology of this nucleus has not been clarified so far. During visual stimulation with a random dot pattern, 45 (35%) neurons were found to be direction selective, 10 (8%) were axis selective (best neuronal responses to rotations in both directions around one particular stimulus axis), and 75 (58%) were movement sensitive. Direction-selective responses were found to the following stimulus directions (in retinal coordinates): temporonasal and nasotemporal horizontal movements, up- and downward vertical movements, and oblique movements. All directions of motion were represented equally by our sample of pretectal neurons. Additionally we tested the responses of 58 of the 130 neurons to random dot patterns rotating around the semicircular canal or body axes to investigate whether direction-selective visual information is mapped into vestibular coordinates in pretectal neurons of this chondrichthyan species. Again all rotational directions were represented equally, which argues against a direct transformation from a retinal to a vestibular reference frame. If a complete transformation had occurred, responses to rotational axes corresponding to the axes of the semicircular canals should have been overrepresented. In conclusion, the recorded direction-selective neurons in the Cgl are plausible detectors for retinal slip created by body rotations in all directions.

Neuronal Responses Related to Smooth Pursuit Eye Movements in the Periarcuate Cortical Area of Monkeys

1998 ◽  
Vol 80 (1) ◽  
pp. 28-47 ◽  
Author(s):  
Masaki Tanaka ◽  
Kikuro Fukushima
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Cortical Area ◽  
Eye Position ◽  
Smooth Pursuit Eye Movements ◽  
Neuronal Responses ◽  
Stationary Target ◽  
Pursuit Eye Movements ◽  
Preferred Direction ◽  
Eye Velocity

Tanaka, Masaki and Kikuro Fukushima. Neuronal responses related to smooth pursuit eye movements in the periarcuate cortical area of monkeys. J. Neurophysiol. 80: 28–47, 1998. To examine how the periarcuate area is involved in the control of smooth pursuit eye movements, we recorded 177 single neurons while monkeys pursued a moving target in the dark. The majority (52%, 92/177) of task-related neurons responded to pursuit but had little or no response to saccades. Histological reconstructions showed that these neurons were located mainly in the posterior bank of the arcuate sulcus near the sulcal spur. Twenty-seven percent (48/177) changed their activity at the onset of saccades. Of these, 36 (75%) showed presaccadic burst activity with strong preference for contraversive saccades. Eighteen (10%, 18/177) were classified as eye-position–related neurons, and 11% (19/177) were related to other aspects of the stimuli or response. Among the 92 neurons that responded to pursuit, 85 (92%) were strongly directional with uniformly distributed preferred directions. Further analyses were performed in these directionally sensitive pursuit-related neurons. For 59 neurons that showed distinct changes in activity around the initiation of pursuit, the median latency from target motion was 96 ms and that preceding pursuit was −12 ms, indicating that these neuron can influence the initiation of pursuit. We tested some neurons by briefly extinguishing the tracking target ( n = 39) or controlling its movement with the eye position signal ( n = 24). The distribution of the change in pursuit-related activity was similar to previous data for the dorsomedial part of the medial superior temporal neurons ( Newsome et al. 1988) , indicating that pursuit-related neurons in the periarcuate area also carry extraretinal signals. For 22 neurons, we examined the responses when the animals reversed pursuit direction to distinguish the effects of eye acceleration in the preferred direction from oppositely directed eye velocity. Almost all neurons discharged before eye velocity reached zero, however, only nine neurons discharged before the eyes were accelerated in the preferred direction. The delay in neuronal responses relative to the onset of eye acceleration in these trials might be caused by suppression from oppositely directed pursuit velocity. The results suggest that the periarcuate neurons do not participate in the earliest stage of eye acceleration during the change in pursuit direction, although most of them may participate in the early stages of pursuit initiation in the ordinary step-ramp pursuit trials. Some neurons changed their activity when the animals fixated a stationary target, and this activity could be distinguished easily from the strong pursuit-related responses. Our results suggest that the periarcuate pursuit area carries extraretinal signals and affects the premotor circuitry for smooth pursuit.

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