Projection of the Retina on Superior Colliculus of Cats

Apter, Julia T.

doi:10.1152/jn.1945.8.2.123

Cited by 141 publications

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“…Evidence implicates the superior colliculus (SC), a topographically organized map of rapid eye movements (saccades) located within the midbrain, in the process of selection for action (Apter, 1945;Robinson, 1972;Wurtz, 1997, 1998;Newsome, 1999, 2001; Krauzlis and Dill, 2002;Keller, 2002, 2004;Carello and Krauzlis, 2004), although exactly how SC contributes to selection for action is unknown. Traditionally, experiments in SC were performed with single spots of light as targets for saccades.…”

Section: Introductionmentioning

confidence: 99%

Saccade Target Selection in the Superior Colliculus: A Signal Detection Theory Approach

Kim¹,

Basso²

2008

J. Neurosci.

103

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How the brain selects one action from among multiple options is unknown. A main tenet of signal detection theory (SDT) is that sensory stimuli are represented as noisy information channels. Therefore, the accuracy of selection might be predicted by how well neuronal activity representing alternatives can be distinguished. Here, we apply an SDT framework to a motor system by recording from superior colliculus (SC) neurons during performance of a color, oddball selection task. We recorded from sets of four neurons simultaneously, each of the four representing one of the four possible targets. Because the electrode placement constrained the position of the stimuli in the visual field, the stimulus arrangement varied across experiments. This variability in stimulus arrangement led to variability in choices allowing us to explore the relationship between SC neuronal activity and performance accuracy. SC target neurons had higher levels of discharge than SC distractor neurons in subsets of trials when selection performance was very accurate. In subsets of trials when performance was poor, the discharge level decreased in target neurons and increased in distractor neurons. Accurate performance was associated with larger separations between neuronal activity from targets and distractors as quantified by the receiver operating characteristic (ROC) area and d (an index of discriminability). Poorer performance was associated with less separation of target and distractor neuronal activity. ROC area and d scaled approximately linearly with performance accuracy. Furthermore, ROC area and d increased as saccade onset approached. Together, the results indicate that SC buildup neuronal activity signals the saccadic eye movement decision.

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Section: Introductionmentioning

confidence: 99%

Saccade Target Selection in the Superior Colliculus: A Signal Detection Theory Approach

Kim¹,

Basso²

2008

J. Neurosci.

103

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“…It has long been known that visual and movement space is represented topographically across the SC; in particular, the eccentricities of visual receptive fields and movement fields decrease gradually from caudal to rostral (Apter 1945;Cynader and Berman 1972;Sparks et al 1976). In the FEF, the eccentricities of visual and movement fields appear to decrease from mediodorsal to ventrolateral .…”

Section: Introductionmentioning

confidence: 99%

Composition and Topographic Organization of Signals Sent From the Frontal Eye Field to the Superior Colliculus

Sommer

Wurtz

2000

Journal of Neurophysiology

330

285

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The frontal eye field (FEF) and superior colliculus (SC) contribute to saccadic eye movement generation, and much of the FEF's oculomotor influence may be mediated through the SC. The present study examined the composition and topographic organization of signals flowing from FEF to SC by recording from FEF neurons that were antidromically activated from rostral or caudal SC. The first and most general result was that, in a sample of 88 corticotectal neurons, the types of signals relayed from FEF to SC were highly diverse, reflecting the general population of signals within FEF rather than any specific subset of signals. Second, many neurons projecting from FEF to SC carried signals thought to reflect cognitive operations, namely tonic discharges during the delay period of a delayed-saccade task (delay signals), elevated discharges during the gap period of a gap task (gap increase signals), or both. Third, FEF neurons discharging during fixation were found to project to the SC, although they did not project preferentially to rostral SC, where similar fixation neurons are found. Neurons that did project preferentially to the rostral SC were those with foveal visual responses and those pausing during the gap period of the gap task. Many of the latter neurons also had foveal visual responses, presaccadic pauses in activity, and postsaccadic increases in activity. These two types of rostral-projecting neurons therefore may contribute to the activity of rostral SC fixation neurons. Fourth, conduction velocity was used as an indicator of cell size to correct for sampling bias. The outcome of this correction procedure suggested that among the most prevalent neurons in the FEF corticotectal population are those carrying putative cognitive-related signals, i.e., delay and gap increase signals, and among the least prevalent are those carrying presaccadic burst discharges but lacking peripheral visual responses. Fifth, corticotectal neurons carrying various signals were biased topographically across the FEF. Neurons with peripheral visual responses but lacking presaccadic burst discharges were biased laterally, neurons with presaccadic burst discharges but lacking peripheral visual responses were biased medially, and neurons carrying delay or gap increase signals were biased dorsally. Finally, corticotectal neurons were distributed within the FEF as a function of their visual or movement field eccentricity and projected to the SC such that eccentricity maps in both structures were closely aligned. We conclude that the FEF most likely influences the activity of SC neurons continuously from the start of fixation, through visual analysis and cognitive manipulations, until a saccade is generated and fixation begins anew. Furthermore, the projection from FEF to SC is highly topographically organized in terms of function at both its source and its termination.

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“…Afferents from retina provide a direct input to the superficial layers of the optic tectum, where a retinotopic map is formed (23)(24)(25)(26). The intermediate and deep layers give rise to projections to brainstem areas and a motor map is formed that is responsible for the coordination of eye, head, and body movements (22,(27)(28)(29).…”

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confidence: 99%

Tectal microcircuit generating visual selection commands on gaze-controlling neurons

Kardamakis

Saitoh

Grillner

2015

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

132

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The optic tectum (called superior colliculus in mammals) is critical for eye-head gaze shifts as we navigate in the terrain and need to adapt our movements to the visual scene. The neuronal mechanisms underlying the tectal contribution to stimulus selection and gaze reorientation remains, however, unclear at the microcircuit level. To analyze this complex-yet phylogenetically conservedsensorimotor system, we developed a novel in vitro preparation in the lamprey that maintains the eye and midbrain intact and allows for whole-cell recordings from prelabeled tectal gaze-controlling cells in the deep layer, while visual stimuli are delivered. We found that receptive field activation of these cells provide monosynaptic retinal excitation followed by local GABAergic inhibition (feedforward). The entire remaining retina, on the other hand, elicits only inhibition (surround inhibition). If two stimuli are delivered simultaneously, one inside and one outside the receptive field, the former excitatory response is suppressed. When local inhibition is pharmacologically blocked, the suppression induced by competing stimuli is canceled. We suggest that this rivalry between visual areas across the tectal map is triggered through long-range inhibitory tectal connections. Selection commands conveyed via gazecontrolling neurons in the optic tectum are, thus, formed through synaptic integration of local retinotopic excitation and global tectal inhibition. We anticipate that this mechanism not only exists in lamprey but is also conserved throughout vertebrate evolution.optic tectum | superior colliculus | GABAergic inhibition | gaze control | evolution V isual scenes are composed of abundant stimuli, and the gaze needs continuously to be redirected toward different objectsan important task for the brain. Current models postulate that stimulus selection occurs through a process involving competitive interaction between different visual stimuli, resulting in the appropriate eye-head movement (1-5). The optic tectum (superior colliculus in mammals) has a causal role in the stimulus selection process (6-12) and not only in the control of saccades and eyehead gaze shifts (13-16). Although the collicular contribution to the selection process is of central importance, the underlying neuronal processes have remained elusive due to methodological limitations. It is our aim here to address this issue in a novel experimental model.The optic tectum is well developed in the lamprey, belonging to the oldest extant vertebrate group that evolved 560 million years ago (17), and it has remained conserved throughout vertebrate phylogeny (18)(19)(20)(21)(22). Afferents from retina provide a direct input to the superficial layers of the optic tectum, where a retinotopic map is formed (23-26). The intermediate and deep layers give rise to projections to brainstem areas and a motor map is formed that is responsible for the coordination of eye, head, and body movements (22,(27)(28)(29).To uncover the mechanisms underlying visual stimulus selection for gaz...

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Projection of the Retina on Superior Colliculus of Cats

Cited by 141 publications

References 0 publications

Saccade Target Selection in the Superior Colliculus: A Signal Detection Theory Approach

Saccade Target Selection in the Superior Colliculus: A Signal Detection Theory Approach

Composition and Topographic Organization of Signals Sent From the Frontal Eye Field to the Superior Colliculus

Tectal microcircuit generating visual selection commands on gaze-controlling neurons

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