Demonstration of artificial visual percepts generated through thalamic microstimulation

Pezaris, John S.; Reid, R. Clay

doi:10.1073/pnas.0608563104

Cited by 163 publications

(141 citation statements)

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“…In the monkey lateral geniculate nucleus, stimulation currents of 40 A were detected by the animal (Pezaris and Reid, 2007). In the ventral caudal nucleus of humans, Patel et al (2006) reported microstimulation detection thresholds as low as 5 A.…”

Section: Discussionmentioning

confidence: 99%

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Voigt¹,

Brecht²,

Houweling³

2008

J. Neurosci.

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In mammals, most sensory information passes through the thalamus before reaching cortex. In the rat whisker system, each macrovibrissa is represented by ϳ250 neurons in the ventral posterior medial nucleus (VPM) of the thalamus and ϳ10,000 neurons in a cortical barrel column. Here we quantify the sensory impact of individual thalamic neurons in the rat VPM. We first trained animals to report microstimulation of VPM. All animals learned to report microstimulation currents of 2-5 A. We then evoked action potentials (APs) in single thalamic neurons close to the microstimulation site using juxtacellular stimulation, adding on average 17.8 APs to 2.6 spontaneous APs during 200 ms current applications. A population analysis revealed that animals responded equally often in single-cell stimulation trials as in catch trials without stimulation, suggesting that APs of single thalamic cells in VPM lead to either no or only a very weak perceptual effect. These results are surprising given the relatively small number of VPM neurons and our previous observations that single neurons in other parts of the vibrissal system do have an impact on perception or motor output. Our findings therefore suggest that neural representations in whisker thalamus are more distributed than in other whisker-related structures.

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Section: Discussionmentioning

confidence: 99%

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Voigt¹,

Brecht²,

Houweling³

2008

J. Neurosci.

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“…In principle, SC BOLD responses could be mediated by antidromic stimulation of either retinal or cortical cells. Yet, a recent study in which the LGN of monkeys was stimulated during the execution of a sequential double-saccade task provided evidence arguing against such a thalamo-retino-tectal signal propagation 20 . Alternatively, SC BOLD may result from the activation of the Meynert cells of the deep cortical layers of V1 that project to SC 21 .…”

Section: Discussionmentioning

confidence: 99%

The effects of electrical microstimulation on cortical signal propagation

et al. 2010

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Recurrence 1Electrical stimulation (ES) is used in animals and humans to study potential causal links between neural activity and specific cognitive functions. Recently, it has found increased application in electrotherapy and neural prostheses as well. However, how ES-elicited signals propagate in brain tissues is still unclear. Here we used combined electrostimulation, neurophysiology, microinjection and fMRI to study the cortical activity patterns elicited during stimulation of cortical afferents in monkeys. We find that stimulation of a site in LGN (lateral geniculate nucleus) increases the fMRI signal in the regions of primary visual cortex (V1) receiving input from that site, but suppresses it in the retinotopically matched regions of extrastriate cortex. In agreement with previous observations, intracranial recordings show that immediately after a stimulation pulse a long-lasting inhibition follows a short excitatory response. Following microinjections of GABA (γ-aminobutyric acid) antagonists in V1, LGN stimulation induces positive fMRI signals in all cortical areas. Taken together, our findings suggest that ES disrupts cortico-cortical signal propagation by silencing the output of any neocortical area whose afferents are electrically stimulated.We recently developed and optimized the esfMRI (combined ES and fMRI) methodology for experiments in anesthetized and behaving monkeys 1, 2 . Our first experiments, including fMRI-based estimations of tissue excitability (rheobase and chronaxie measurements), showed that electrical stimulation of the primary visual cortex V1 mainly excites large pyramidal cells and axons, eliciting positive BOLD responses (PBR) in topographically matched regions of extrastriate areas such as V2, V3, V3A, V4, and MT (V5); all monosynaptic targets of the primary visual cortex. These findings are consistent with the well-established anatomical connections between V1 and the extrastriate cortex of macaque monkeys 3 . One puzzling observation in our initial studies was the clear lack of transsynaptic effects during cortical stimulation. In the present study, we stimulated either the LGN or the pulvinar (Pul) in anesthetized and alert monkeys in order to systematically examine the propagation of ES-induced signals.We demonstrate that electrical stimulation of a thalamic site indeed suppresses the neural activity of its projection regions in visual cortex. The strong reduction in BOLD response is likely due to synaptic inhibition and it be can be reversed by injections of GABA antagonists in V1. In agreement with the fMRI results, intracortical recordings show that an electric pulse evokes an action potential followed by a pronounced and long-lasting inhibition. Such disruptive effects of cortical afferent stimulation on the activity of projection neurons have already been reported. Yet, by using the combined physiology, pharmacology and fMRI approach here we illustrate for the first time the extent and generality of ES-induced activity suppression, and we propose that many behavioral e...

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“…However, Purkinje cells of the cerebellum and various neurons in the cerebral cortex and elsewhere have no known relationship to circadian photoreception. Phosphenes can also be produced by electrically stimulating the lateral geniculate nucleus (LGN) (Pezaris and Reid, 2007).…”

Section: Endogenous Photoperception Of Bioluminescent Biophotons By Nmentioning

confidence: 99%

Phosphene phenomenon: A new concept

Bókkon

2008

Biosystems

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This paper proposes a new biopsychophysical concept of phosphene phenomenon. Namely, visual sensation of phosphenes is due to the intrinsic perception of ultraweak bioluminescent photon emission of cells in the visual system. In other words, phosphenes are bioluminescent biophotons in the visual system induced by various stimuli (mechanical, electrical, magnetic, ionizing radiation, etc.) as well as random bioluminescent biophotons firings of cells in the visual pathway. This biophoton emission can become conscious if induced or spontaneous biophoton emission of cells in the visual system exceeds a distinct threshold. Neuronal biophoton communication can occur by means of non-visual neuronal opsins and natural photosensitive biomolecules. Our interpretation is in direct connection with the functional roles of free radicals and excited biomolecules in living cells.

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Demonstration of artificial visual percepts generated through thalamic microstimulation

Cited by 163 publications

References 35 publications

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

The effects of electrical microstimulation on cortical signal propagation

Phosphene phenomenon: A new concept

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