scholarly journals Visual Responses of Mosquitoes Artificially Rendered Flightless

1947 ◽  
Vol 24 (1-2) ◽  
pp. 64-78 ◽  
Author(s):  
T. RAMACHANDRA RAO
Keyword(s):  
Visual Field ◽  
Negative Phototaxis ◽  
Visual Responses ◽  
Light Reduction ◽  
Vertical Band ◽  
Anopheles Maculipennis ◽  
Turning Response ◽  
Natural Movement ◽  
Black Band

Most females of Anopheles maculipennis and Culex molestus which had been rendered flightless by removal of wings or by sticking the wings together, tended to move towards a black vertical band when it was presented to them in an arena uniformly illuminated from below. The narrowest width of the band to which they could consistently respond was 0.5 cm. at a distance of 3.5 cm. corresponding to an angle of about 8°. When the edge of a wide black band was exactly in front of the mosquito or at about 45° to one side the movement towards it was consistent, but when the band was placed more and more posteriorly consistency of the responses progressively decreased. When offered simultaneously two black bands of equal or different widths the movement was to one of them. If a new band came into the view when the mosquito was already moving towards another, a turning response towards the new one took place very frequently. Unilaterally blinded specimens performed circus movements in uniform light. When a narrow black band came into the visual field of the functional eye there was an immediate turning response towards it. The negative phototaxis continued even at and after dusk at a time when flying mosquitoes were showing natural movement towards the evening light. Reduction of intensity of illumination and also the natural fading of the light at dusk both failed to bring about a reversal of response. For some undetermined reason mosquitoes rendered flightless always tend to move away from light. The mechanism of orientation seems to be in conformity with current ideas of negative phototropotaxis. No evidence of a photohorotaxis was secured.

Visual Responses of the Human Superior Colliculus: A High-Resolution Functional Magnetic Resonance Imaging Study

2005 ◽  
Vol 94 (4) ◽  
pp. 2491-2503 ◽  
Author(s):  
Keith A. Schneider ◽  
Sabine Kastner
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
High Resolution ◽  
Superior Colliculus ◽  
Visual Fields ◽  
Visual Response ◽  
Visual Responses ◽  
Subcortical Structures ◽  
Stimulus Motion ◽  
Low Contrast

The superior colliculus (SC) is a multimodal laminar structure located on the roof of the brain stem. The SC is a key structure in a distributed network of areas that mediate saccadic eye movements and shifts of attention across the visual field and has been extensively studied in nonhuman primates. In humans, it has proven difficult to study the SC with functional MRI (fMRI) because of its small size, deep location, and proximity to pulsating vascular structures. Here, we performed a series of high-resolution fMRI studies at 3 T to investigate basic visual response properties of the SC. The retinotopic organization of the SC was determined using the traveling wave method with flickering checkerboard stimuli presented at different polar angles and eccentricities. SC activations were confined to stimulation of the contralateral hemifield. Although a detailed retinotopic map was not observed, across subjects, the upper and lower visual fields were represented medially and laterally, respectively. Responses were dominantly evoked by stimuli presented along the horizontal meridian of the visual field. We also measured the sensitivity of the SC to luminance contrast, which has not been previously reported in primates. SC responses were nearly saturated by low contrast stimuli and showed only small response modulation with higher contrast stimuli, indicating high sensitivity to stimulus contrast. Responsiveness to stimulus motion in the SC was shown by robust activations evoked by moving versus static dot stimuli that could not be attributed to eye movements. The responses to contrast and motion stimuli were compared with those in the human lateral geniculate nucleus. Our results provide first insights into basic visual responses of the human SC and show the feasibility of studying subcortical structures using high-resolution fMRI.

scholarly journals Visuospatial coding in primate prefrontal neurons revealed by oculomotor paradigms

1990 ◽  
Vol 63 (4) ◽  
pp. 814-831 ◽  
Author(s):  
S. Funahashi ◽  
C. J. Bruce ◽  
P. S. Goldman-Rakic
Keyword(s):  
Prefrontal Cortex ◽  
Visual Field ◽  
Visual Cues ◽  
Neuron Activity ◽  
Delayed Response ◽  
Visual Response ◽  
Visual Responses ◽  
Directional Tuning ◽  
Vertical Meridian ◽  
Visual Probe

1. Visual responses and their relationship to delay-period activity were studied by recording single neuron activity from the prefrontal cortex of rhesus monkeys while they performed an oculomotor delayed-response (ODR) and a visual probe (VP) task. In the ODR task, the monkey was required to maintain fixation of a central spot of light throughout the cue (0.5 s) and delay (3 s) periods and then make a saccadic eye movement to one of four or eight locations where the visual cue had been presented. In the VP task, the same visual stimuli that were used in the ODR task were presented for 0.5 s, but no response was required. The VP task was thus employed to test the passive visual response and, by comparison with cue-elicited activity in the ODR task, to examine the degree of behavioral enhancement present in prefrontal visual activity. 2. Among 434 neurons recorded from the prefrontal cortex within and surrounding the principal sulcus (PS), 261 had task-related activity during at least one phase of the ODR task, and 74 of these had phasic visual responses to the onset of the visual cues with a median latency of 116 ms. The visual responses of 69 neurons were excitatory, and 5 neurons were inhibited. Five of the neurons with excitatory visual responses also responded transiently after the offset of the cue. 3. Visual responses were classified as directional for 71 PS neurons (96%) in that excitatory or inhibitory responses occurred only for location of cues in a restricted portion of the visual field. Only 3 PS neurons were omnidirectional, i.e., responded equivalently to cues in all locations tested. 4. The best direction and tuning specificity of all PS neurons with directional visual responses were estimated from parameters yielding the best fit to a Gaussian-shaped tuning function. The best direction for the majority (71%) of neurons was toward the visual field contralateral to the hemisphere where the neuron was located. The remaining neurons had their best directions in the ipsilateral field (18%) or along the vertical meridian (11%). 5. The specificity of directional tuning for PS visual responses was quite variable, ranging from neurons that responded only to one of the eight cue locations to neurons that responded to all eight, but in a clearly graded fashion. The standard deviation parameter of the Gaussian curve indexed the breadth of directional tuning of each neuron; its median value was 37 degrees.(ABSTRACT TRUNCATED AT 400 WORDS)

Visual responses and connectivity in the turtle pretectum

1995 ◽  
Vol 73 (6) ◽  
pp. 2507-2521 ◽  
Author(s):  
T. X. Fan ◽  
A. E. Weber ◽  
G. E. Pickard ◽  
K. M. Faber ◽  
M. Ariel
Keyword(s):  
Visual Field ◽  
Brain Stem ◽  
Optic Tectum ◽  
Visual Stimulation ◽  
Visual Pattern ◽  
Visual Responses ◽  
Anterograde Transport ◽  
Lentiform Nucleus ◽  
Retinal Stimulation ◽  
Slow Moving

1. Using an isolated turtle brain preparation, we made extracellular spike recordings in the dorsal midbrain during visual stimulation. Single units were isolated by their response to a slow-moving full-field visual pattern imaged on the contralateral retina. This stimulus elicits responses from the basal optic nucleus (BON) and the cerebellar cortex using a similar preparation. Direction and speed tuning were then analyzed, as well as the size and position of the receptive field. 2. In one brain stem region, anterior to the optic tectum and deep to the dorsal surface, all of the visually responsive neurons were direction sensitive (DS) to contralateral retinal stimulation. The location and properties of these cells indicate that they are in the mesencephalic lentiform nucleus (nLM). Anterograde transport of intravitreally injected horseradish peroxidase revealed that this pretectal nucleus receives direct input from the contralateral eye. 3. All but 2 of the 48 cells of the nLM were strongly DS. The most effective stimulus was a slowly moving complex visual pattern that drifted nasally in the contralateral visual field. Brief flashes of spots, patterns, or diffuse light were much less effective. Receptive fields were large and usually (9 of 13 cells) centered in the superior visual field near the horizon and nasal to the blind spot. 4. The visual responses of nLM cells were compared to those of cells in the superficial layers of the optic tectum. In contrast to nLM, the responses of tectal cells were heterogeneous and frequently not DS. Neither tectum or nLM cells had much spontaneous spike activity during darkness or stationary patterns. On the other hand, visual responses of nLM cells were very similar to those of the BON, where neurons also had low spontaneous activity, preferred slow-moving patterns, and were DS. However, nLM and BON exhibit different distributions of preferred directions. Most nLM cells preferred temporal-to-nasal motion, whereas BON cells preferred almost any direction, although few preferred the nasal direction. nLM cell responses were not affected by removal of the ventral brain stem including the BON. 5. The visual properties of nLM cells recorded in vitro were very similar to those that were recorded in intact turtles.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals The posterior parietal cortex contributes to visuomotor processing for saccades in blindsight macaques

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Rikako Kato ◽  
Takuya Hayashi ◽  
Kayo Onoe ◽  
Masatoshi Yoshida ◽  
Hideo Tsukada ◽  
...  
Keyword(s):  
Visual Field ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Visual Awareness ◽  
Functional Brain Imaging ◽  
Intraparietal Sulcus ◽  
Visual Responses ◽  
Primate Model ◽  
Positron Emission ◽  
Posterior Parietal

AbstractPatients with damage to the primary visual cortex (V1) lose visual awareness, yet retain the ability to perform visuomotor tasks, which is called “blindsight.” To understand the neural mechanisms underlying this residual visuomotor function, we studied a non-human primate model of blindsight with a unilateral lesion of V1 using various oculomotor tasks. Functional brain imaging by positron emission tomography showed a significant change after V1 lesion in saccade-related visuomotor activity in the intraparietal sulcus area in the ipsi- and contralesional posterior parietal cortex. Single unit recordings in the lateral bank of the intraparietal sulcus (lbIPS) showed visual responses to targets in the contralateral visual field on both hemispheres. Injection of muscimol into the ipsi- or contralesional lbIPSs significantly impaired saccades to targets in the V1 lesion-affected visual field, differently from previous reports in intact animals. These results indicate that the bilateral lbIPSs contribute to visuomotor function in blindsight.

scholarly journals Neuronal circuitry for stimulus selection in the visual system

2019 ◽  
Author(s):  
António M. Fernandes ◽  
Johannes Larsch ◽  
Joseph C. Donovan ◽  
Thomas O. Helmbrecht ◽  
Duncan Mearns ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Saliency ◽  
Saliency Map ◽  
Inhibitory Neurons ◽  
Stimulus Selection ◽  
Visual Responses ◽  
Classical Receptive Field ◽  
Single Cell Responses ◽  
Winner Take All ◽  
First Time

Visual objects naturally compete for the brain’s attention, and selecting just one of them for a behavioural response is often crucial for the animal’s survival1. The neural correlate of such stimulus prioritisation might take the form of a saliency map by which responses to one target are enhanced relative to distractors in other parts of the visual field2. Single-cell responses consistent with this type of computation have been observed in the tectum of primates, birds, turtles and lamprey2–7. However, the exact circuit implementation has remained unclear. Here we investigated the underlying neuronal mechanism presenting larval zebrafish with two simultaneous looming stimuli, each of which was able to trigger directed escapes on their own. Behaviour tracking revealed that the fish respond to these competing stimuli predominantly with a winner-take-all strategy. Using brain-wide functional recordings, we discovered neurons in the tectum whose responses to the target stimulus were non-linearly modulated by the saliency of the distractor. When the two stimuli were presented monocularly in different positions of the visual field, stimulus selection was already apparent in the activity of retinal ganglion cell axons, a likely consequence of antagonistic mechanisms operating outside the classical receptive field8,9. When the two stimuli were presented binocularly, i.e., on opposite sides of the fish, our analysis indicates that a loop involving excitatory and inhibitory neurons in the nucleus isthmi (NI) and the tectum weighed stimulus saliencies across hemispheres. Consistent with focal enhancement and global suppression, glutamatergic NI cells branch locally in the tectum, whereas GABAergic NI cells project broadly across both tectal hemispheres. Moreover, holographic optogenetic stimulation confirmed that glutamatergic NI neurons can modulate visual responses in the tectum. Together, our study shows, for the first time, context-dependent contributions of retinotectal and isthmotectal circuits to the computation of the visual saliency map, a prerequisite for stimulus-driven, bottom-up attention.

Both striate cortex and superior colliculus contribute to visual properties of neurons in superior temporal polysensory area of macaque monkey

1986 ◽  
Vol 55 (5) ◽  
pp. 1057-1075 ◽  
Author(s):  
C. J. Bruce ◽  
R. Desimone ◽  
C. G. Gross
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Superior Colliculus ◽  
Striate Cortex ◽  
Visual Stimuli ◽  
Receptive Fields ◽  
Visual Responses ◽  
Stimulus Motion ◽  
Visual Hemifields ◽  
Visual Properties

Although the tectofugal system projects to the primate cerebral cortex by way of the pulvinar, previous studies have failed to find any physiological evidence that the superior colliculus influences visual activity in the cortex. We studied the relative contributions of the tectofugal and geniculostriate systems to the visual properties of neurons in the superior temporal polysensory area (STP) by comparing the effects of unilateral removal of striate cortex, the superior colliculus, or of both structures. In the intact monkey, STP neurons have large, bilateral receptive fields. Complete unilateral removal of striate cortex did not eliminate visual responses of STP neurons in the contralateral visual hemifield; rather, nearly half the cells still responded to visual stimuli in the hemifield contralateral to the lesion. Thus the visual properties of STP neurons are not completely dependent on the geniculostriate system. Unilateral striate lesions did affect the response properties of STP neurons in three ways. Whereas most STP neurons in the intact monkey respond similarly to stimuli in the two visual hemifields, responses to stimuli in the hemifield contralateral to the striate lesion were usually weaker than responses in the ipsilateral hemifield. Whereas the responses of many STP neurons in the intact monkey were selective for the direction of stimulus motion or for stimulus form, responses in the hemifield contralateral to the striate lesion were not selective for either motion or form. Whereas the median receptive field in the intact monkey extended 80 degrees into the contralateral visual field, the receptive fields of cells with responses in the contralateral field that survived the striate lesions had a median border that extended only 50 degrees into the contralateral visual field. Removal of both striate cortex and the superior colliculus in the same hemisphere abolished the responses of STP neurons to visual stimuli in the hemifield contralateral to the combined lesion. Nearly 80% of the cells still responded to visual stimuli in the hemifield ipsilateral to the lesion. Unilateral removal of the superior colliculus alone had only small effects on visual responses in STP. Receptive-field size and visual response strength were slightly reduced in the hemifield contralateral to the collicular lesion. As in the intact monkey, selectivity for stimulus motion or form were similar in the two visual hemifields. We conclude that both striate cortex and the superior colliculus contribute to the visual responses of STP neurons. Striate cortex is crucial for the movement and stimulus specificity of neurons in STP.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Aberrant Visual Population Receptive Fields in Human Albinism

2019 ◽  
Author(s):  
Ethan J. Duwell ◽  
Erica N. Woertz ◽  
Jedidiah Mathis ◽  
Joseph Carroll ◽  
Edgar A. DeYoe
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Spatial Information ◽  
Receptive Fields ◽  
Visual Space ◽  
Mirror Image ◽  
Visual Responses ◽  
Central Visual Field ◽  
Vertical Meridian ◽  
The Right

ABSTRACTRetinotopic organization is a fundamental feature of visual cortex thought to play a vital role in encoding spatial information. One important aspect of normal retinotopy is the representation of the right and left hemifields in contralateral visual cortex. However, in human albinism, many temporal retinal afferents decussate pathologically at the optic chiasm resulting in partially superimposed representations of opposite hemifields in each hemisphere of visual cortex. Previous fMRI studies in human albinism suggest that the right and left hemifield representations are superimposed in a mirror-symmetric manner. This should produce imaging voxels which respond to two separate regions in visual space mirrored across the vertical meridian. However, it is not yet clear how retino-cortical miswiring in albinism manifests at the level of single voxel population receptive fields. Here we used fMRI retinotopic mapping in conjunction with population receptive field (pRF) modeling to fit both single and dual pRF models to the visual responses of voxels in visual areas V1-V3 of five subjects with albinism. We found that subjects with albinism (but not controls) have sizable clusters of voxels with dual pRFs consistently corresponding to, but not fully coextensive with regions of hemifield overlap. These dual pRFs were typically positioned at roughly mirror image locations across the vertical meridian but were uniquely clustered within the visual field for each subject. We also found that single pRFs are larger in albinism than controls, and that single pRF sizes in the central visual field were anti-correlated with subjects’ foveal cone densities. Finally, dual pRF and aberrant hemifield representation characteristics varied significantly across subjects with albinism suggesting more central heterogeneity than previously appreciated.

Effects of attention and stimulus interaction on visual responses of inferior temporal neurons in macaque

1988 ◽  
Vol 60 (1) ◽  
pp. 344-364 ◽  
Author(s):  
T. Sato
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Discrimination Task ◽  
Temporal Cortex ◽  
Pattern Discrimination ◽  
Suppressive Effect ◽  
Neutral Stimulus ◽  
Inferior Temporal Cortex ◽  
Visual Response ◽  
Visual Responses

1. Extracellular discharges were recorded from neurons in the inferior temporal cortex (area TE) of three macaque monkeys while they performed visual fixation and pattern discrimination tasks. For the pattern discrimination task, monkey was trained to release the lever quickly at the onset of one of two pattern stimuli and to release the lever at the dimming of the other pattern. During this task, neutral light stimulus (light bar) to which the monkey was not required to respond was presented once a trial either prior to the onset of the discriminandum or during presentation of the pattern that dimmed later. The neuronal activities evoked by the neutral stimulus under these two conditions were compared. 2. When the discriminanda were located at the center or at 5 degrees in the contralateral visual field, one-half of the neurons showed significantly smaller responses to the neutral stimulus when it was presented during presentation of the dimming pattern than when it was presented prior to the onset of the discriminandum. 3. The suppressive effect depended on the location of the two stimuli. When the neutral stimulus was located in the ipsilateral visual field and the pattern was located in the contralateral visual field, the response to the neutral stimulus was suppressed. However, when the pattern was located in the ipsilateral visual field (5 degrees visual angle), still within the receptive field for many neurons, the suppressive effect of the pattern on the response to the neutral stimulus in the contralateral visual field was almost undetectable. 4. When the pattern was located nearer the fovea than was the neutral stimulus, the suppressive effect was greater than when the pattern was located more peripherally to the neutral stimulus. Different from the receptive field of more primary visual neurons, this suppressive effect did not appear to be related to the neuron's responsiveness to the patterns nor to precise stimulus location in the receptive field. 5. The magnitude of suppression by the attended pattern on the visual response during the pattern discrimination task correlated with the suppression noted in the presence of a fixation spot during the fixation tasks, while the animals did not fixate on the attended pattern. The response of some neurons to the neutral stimulus prior to pattern presentation during the pattern discrimination task was enhanced slightly compared with the response recorded during the simple fixation task.(ABSTRACT TRUNCATED AT 400 WORDS)

Control of orienting gaze shifts by the tectoreticulospinal system in the head-free cat. I. Identification, localization, and effects of behavior on sensory responses

1991 ◽  
Vol 66 (5) ◽  
pp. 1605-1623 ◽  
Author(s):  
D. Guitton ◽  
D. P. Munoz
Keyword(s):  
Spinal Cord ◽  
Visual Field ◽  
Receptive Fields ◽  
Lower Visual Field ◽  
Visual Responses ◽  
Abducens Nucleus ◽  
Orienting Behavior ◽  
Conduction Velocities ◽  
The Mean ◽  
Sensory Responses

1. The input-output connectivity, in cat, of tectoreticular (TRNs) and tectoreticulospinal (TRSNs) neurons [together called TR(S)Ns] suggests a role for these cells in the sensorimotor transformations necessary for controlling orienting behavior. Multimodal sensory information converges directly onto these tectal neurons, and they project to several brain stem and spinal cord centers involved in the control of eye- and head-orienting movements. In this and the following two papers, we describe the sensorimotor discharges of antidromically identified TR(S)Ns. Here we describe the process of localizing and identifying them, characteristics of both their antidromic and sensory responses, and effects of behavioral context on these responses. 2. In 13 alert, chronically prepared cats, a total of 293 neurons were antidromically identified from either the predorsal bundle (PDB) immediately rostral to abducens nucleus or the ventromedial funiculus of the spinal cord at the level of the first cervical vertebra (C1). The cell bodies of all identified TR(S)Ns were confined to the intermediate and deep laminae of the superior colliculus (SC). The antidromic nature of the action potential evoked by stimulating either the PDB or C1 was verified by the use of a number of established criteria, including collision testing. 3. The mean antidromic latency from the PDB (TRNs + TRSNs) was 0.84 +/- 0.59 (SD) ms (n = 217). The conduction velocities of all cells activated by PDB stimulation ranged from 4 to 40 m/s. The mean latency from C1 (TRSNs) was 1.03 +/- 0.52 ms (SD) (n = 64), whereas conduction velocities ranged from 14 to 80 m/s. 4. One hundred thirty-eight TR(S)Ns were studied long enough to yield significant data regarding their involvement in visuomotor-orienting behavior. Ninety-eight percent (130/133) of the TR(S)Ns tested for visual responses could be induced to discharge action potentials in response to some form of visual stimulation. The other three neurons remained silent, even in response to the most provocative stimuli. These silent neurons nevertheless were shown to be depolarized by visual stimuli. TR(S)Ns were occasionally tested for auditory and somatosensory responses and some were multimodal. 5. TR(S)Ns had visual receptive fields that conformed to the retinotopic map of the visual field that is represented within the SC. Cells found in the lateral SC had receptive fields located in the lower visual field, whereas neurons that were situated medially had receptive fields in the upper visual field. Cells found in the rostral SC had small fields that included a representation of the area centralis.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Sustained High- and Low-Frequency Neural Responses to Visual Stimuli in Scalp EEG

2018 ◽  
Author(s):  
Edden M. Gerber ◽  
Leon Y. Deouell
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Visual Processing ◽  
High Frequency ◽  
Visual Stimuli ◽  
Low Frequency ◽  
Right Visual Field ◽  
Visual Responses ◽  
Scalp Eeg ◽  
Sustained Responses

AbstractWhat are the neurophysiological correlates of sustained visual processing in the scalp EEG signal? In a previous study using intracranial recordings in humans, we found that presentation of visual stimuli for prolonged durations (up to 1.5 seconds) was associated with two kinds of sustained neural activity patterns: a high-frequency broadband (>30 Hz) response that tracked the duration of the stimulus with high precision in early visual cortex (EVC), and with lesser temporal precision in downstream category-selective areas; and a sustained low-frequency potential shift appearing in a small subset of EVC sites. Using a similar approach of presenting images for variable durations to identify sustained activity, we provide the first comprehensive characterization of the manifestation of sustained visual responses as recorded with EEG. In a series of four experiments, we found that both high- and low-frequency sustained responses can be detected on the scalp. The high frequency activity could be detected with high signal to noise ratio only in a subset of individual subjects, in whom it was unequivocal and highly localized. The low frequency sustained response was sensitive to the size and position of the stimulus in the visual field. Both response types showed strong lateralization for stimuli on the left vs. right visual field, suggesting a retinotopic visual cortical source. However, different scalp topographies and different modulation by stimulus properties suggest that the two types of sustained responses are likely driven by distinct sources, and reflect different aspects of sustained processing in the visual cortex.

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