scholarly journals Peter Orlebar Bishop. 14 June 1917—3 June 2012

2018 ◽  
Vol 64 ◽  
pp. 51-68
Author(s):  
Jack D. Pettigrew ◽  
Bogdan Dreher
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Great Ability ◽  
Visual Research ◽  
Talented People ◽  
Relay Nucleus ◽  
Single Neurones ◽  
Schematic Eye ◽  
Dorsal Lateral Geniculate

Peter Orlebar Bishop was an Australian neurophysiologist renowned for his ingenious quantitative approach to the study of the mammalian visual system and his great ability to attract a large number of talented people to visual research. Peter’s research was based on specially designed, precise instrumentation and data quantification applied mainly to analysis of the response properties of single neurones in the principal dorsal thalamic visual relay nucleus, the dorsal lateral geniculate nucleus (LGNd) and the primary visual cortex. This quantitative bent was evident throughout Peter’s entire research career: starting with the design and construction of innovative DC amplifiers; to his quantitative analysis of optics, ‘schematic eye’ for the cat, which rivalled Gullstrand’s schematic eye for humans; to creating and demonstrating validity of the concept of ‘projection lines’ in the representation of contralateral visual field in different cellular layers of the LGNd of mammals with frontally positioned eyes and discovery of massive binocular input to single LGNd neurones. Peter’s engineering approach was probably at its heuristic peak when it revealed many details of binocular interactions at the level of single neurones in the primary visual cortex—the interactions which appear to underpin overall mechanisms underlying stereopsis, the high precision binocular depth sense.

Peter Orlebar Bishop 1917–2012

2018 ◽  
Vol 29 (2) ◽  
pp. 162
Author(s):  
Jack D. Pettigrew ◽  
B. Dreher
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Great Ability ◽  
Visual Research ◽  
Talented People ◽  
Relay Nucleus ◽  
Single Neurones ◽  
Schematic Eye ◽  
Dorsal Lateral Geniculate

Peter Orlebar Bishop was an Australian neurophysiologist renowned for his ingenious quantitative approach to study of the mammalian visual system and great ability to attract a large number of talented people to visual research. Peter's research was based on specially designed, precise instrumentation and data quantification applied mainly to analysis of the response properties of single neurones in the principal dorsal thalamic visual relay nucleus, the dorsal lateral geniculate nucleus (LGNd) and the primary visual cortex. This quantitative bent was evident throughout Bishop's entire research career:starting with the design and construction of innovative DC amplifiers; through to his quantitative analysis of optics—‘schematic eye' for the cat, which rivaled Gullstrand's schematic eye for humans; to creating and demonstrating validity of the concept of ‘projection lines' in the representation of contralateral visual field in different cellular layers of the LGNd of mammals with frontally positioned eyes and discovery of a very substantial binocular input to single LGNd neurones. The engineering approach of Peter was probably at its heuristic peak when it revealed many details of binocular interactions at the level of single neurones in the primary visual cortex—the interactions that appear to underpin overall mechanisms underlying stereopsis, the high precision binocular depth sense.

scholarly journals Extrastriate Connectivity of the Mouse Dorsal Lateral Geniculate Thalamus

2018 ◽  
Author(s):  
Michael S. Bienkowski ◽  
Nora L. Benavidez ◽  
Kevin Wu ◽  
Lin Gou ◽  
Marlene Becerra ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Visual System ◽  
Lateral Geniculate Nucleus ◽  
Primary Visual Cortex ◽  
Visual Information ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Lateral Geniculate ◽  
Visual Cortices ◽  
Dorsal Lateral Geniculate

AbstractThe mammalian visual system is one of the most well-studied brain systems. Visual information from the retina is relayed to the dorsal lateral geniculate nucleus of the thalamus (LGd). The LGd then projects topographically to primary visual cortex (VISp) to mediate visual perception. In this view, the VISp is a critical network hub where visual information must traverse LGd-VISp circuits to reach higher-order ‘extrastriate’ visual cortices. However, decades of conflicting reports in a variety of mammals support or refute the existence of extrastriate LGd connections that can bypass the VISp. Here, we provide evidence of bidirectional extrastriate connectivity with the mouse LGd. Using small, discrete coinjections of anterograde and retrograde tracers within the thalamus and cortex, our cross-validated approach identified bidirectional thalamocortical connectivity between LGd and extrastriate visual cortices. Our findings support the existence of extrastriate LGd circuits and provide novel understanding of LGd organization in rodent visual system.

scholarly journals Morphological and Physiological Characterization of Layer VI Corticofugal Neurons of Mouse Primary Visual Cortex

2003 ◽  
Vol 89 (5) ◽  
pp. 2854-2867 ◽  
Author(s):  
Joshua C. Brumberg ◽  
Farid Hamzei-Sichani ◽  
Rafael Yuste
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Action Potentials ◽  
Three Dimensional ◽  
Cell Types ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Morphological Properties ◽  
Feedback Connection ◽  
Physiological Characterization ◽  
Layer Vi

Layer VI is the origin of the massive feedback connection from the cortex to the thalamus, yet its complement of cell types and their connections is poorly understood. The physiological and morphological properties of corticofugal neurons of layer VI of mouse primary visual cortex were investigated in slices loaded with the Ca2+indicator fura-2AM. To identify corticofugal neurons, electrical stimulation of the white matter (WM) was done in conjunction with calcium imaging to detect neurons that responded with changes in intracellular Ca2+ concentrations in response to the stimulation. Subsequent whole cell recordings confirmed that they discharged antidromic action potentials after WM stimulation. Antidromically activated neurons were more excitable and had different spiking properties than neighboring nonantidromic neurons, although both groups had similar input resistances. Furthermore, antidromic neurons possessed narrower action potentials and smaller afterhyperpolarizations. Additionally, three-dimensional reconstructions indicated that antidromically activated neurons had a distinct morphology with longer apical dendrites and fewer nonprimary dendrites than nonantidromic cells. To identify the antidromic neurons, rhodamine microspheres were injected into the dorsal lateral geniculate nucleus of the thalamus and allowed to retrogradely transport back to the somata of the layer VI cortico-geniculate neurons. Physiological and anatomical analysis indicated that most antidromic neurons were likely to be cortico-geniculate neurons. Our results show that cortico-thalamic neurons represent a specific functional and morphological class of layer VI neurons.

scholarly journals Cholinergic Modulation Promotes Attentional Modulation in Primary Visual Cortex- A Modeling Study

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Atena Sajedin ◽  
Mohammad Bagher Menhaj ◽  
Abdol-Hossein Vahabie ◽  
Stefano Panzeri ◽  
Hossein Esteky
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Cholinergic System ◽  
Neuronal Excitability ◽  
Sensory Information ◽  
Inhibitory Neurons ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Cholinergic Modulation ◽  
Gamma Power ◽  
Sensory Neural

AbstractAttention greatly influences sensory neural processing by enhancing firing rates of neurons that represent the attended stimuli and by modulating their tuning properties. The cholinergic system is believed to partly mediate the attention contingent improvement of cortical processing by influencing neuronal excitability, synaptic transmission and neural network characteristics. Here, we used a biophysically based model to investigate the mechanisms by which cholinergic system influences sensory information processing in the primary visual cortex (V1) layer 4C. The physiological properties and architectures of our model were inspired by experimental data and include feed-forward input from dorsal lateral geniculate nucleus that sets up orientation preference in V1 neural responses. When including a cholinergic drive, we found significant sharpening in orientation selectivity, desynchronization of LFP gamma power and spike-field coherence, decreased response variability and correlation reduction mostly by influencing intracortical interactions and by increasing inhibitory drive. Our results indicated that these effects emerged due to changes specific to the behavior of the inhibitory neurons. The behavior of our model closely resembles the effects of attention on neural activities in monkey V1. Our model suggests precise mechanisms through which cholinergic modulation may mediate the effects of attention in the visual cortex.

scholarly journals Hour-long adaptation in the awake early visual system

2015 ◽  
Vol 114 (2) ◽  
pp. 1172-1182 ◽  
Author(s):  
Carl R. Stoelzel ◽  
Joseph M. Huff ◽  
Yulia Bereshpolova ◽  
Jun Zhuang (庄骏) ◽  
Xiaojuan Hei (黑晓娟) ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spontaneous Activity ◽  
Visual Stimulation ◽  
Sensory Stimulation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Visual Signal ◽  
Induced Response ◽  
Sensory Adaptation ◽  
Layer 4 ◽  
Dorsal Lateral Geniculate

Sensory adaptation serves to adjust awake brains to changing environments on different time scales. However, adaptation has been studied traditionally under anesthesia and for short time periods. Here, we demonstrate in awake rabbits a novel type of sensory adaptation that persists for >1 h and acts on visual thalamocortical neurons and their synapses in the input layers of the visual cortex. Following prolonged visual stimulation (10–30 min), cells in the dorsal lateral geniculate nucleus (LGN) show a severe and prolonged reduction in spontaneous firing rate. This effect is bidirectional, and prolonged visually induced response suppression is followed by a prolonged increase in spontaneous activity. The reduction in thalamic spontaneous activity following prolonged visual activation is accompanied by increases in 1) response reliability, 2) signal detectability, and 3) the ratio of visual signal/spontaneous activity. In addition, following such prolonged activation of an LGN neuron, the monosynaptic currents generated by thalamic impulses in layer 4 of the primary visual cortex are enhanced. These results demonstrate that in awake brains, prolonged sensory stimulation can have a profound, long-lasting effect on the information conveyed by thalamocortical inputs to the visual cortex.

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