Jens Kremkow

Jens Kremkow
State University of New York College of Optometry | SUNY OPT · Biological Sciences

PhD

About

52
Publications
6,292
Reads
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1,500
Citations
Citations since 2017
15 Research Items
950 Citations
2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150
Additional affiliations
August 2009 - December 2010
University of Freiburg
Position
  • PostDoc Position
January 2006 - July 2009
CNRS / Aix-Marseille Université
Position
  • PhD
January 2006 - July 2009
University of Freiburg
Position
  • PhD

Publications

Publications (52)
Preprint
Thalamus provides the principal input to cortex, thus understanding the mechanisms of cortical computations in behaving animals requires to characterize the thalamocortical connectivity in vivo. We show that tangential insertions of high-density electrodes into mouse cortex capture the activity of thalamocortical axons simultaneously with their syn...
Article
Full-text available
The superior colliculus is a midbrain structure that plays important roles in visually guided behaviors in mammals. Neurons in the superior colliculus receive inputs from retinal ganglion cells but how these inputs are integrated in vivo is unknown. Here, we discovered that high-density electrodes simultaneously capture the activity of retinal axon...
Article
Full-text available
Among the different autism spectrum disorders, Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. Sensory and especially auditory hypersensitivity is a key symptom in patients, which is well mimicked in the Fmr1 -/- mouse model. However, the physiological mechanisms underlying FXS’s acoustic hypersensitivity in...
Article
Background The superior colliculus (SC) is a midbrain structure that plays a central role in visual processing. Although we have learned a considerable amount about the function of single SC neurons, the way in which sensory information is represented and processed on the population level in awake behaving animals and across a large region of the r...
Article
Full-text available
The cerebral cortex receives multiple afferents from the thalamus that segregate by stimulus modality forming cortical maps for each sense. In vision, the primary visual cortex also maps the multiple dimensions of the stimulus in patterns that vary across species for reasons unknown. Here we introduce a general theory of cortical map formation, whi...
Preprint
Neurons in the mouse superior colliculus (SC) are arranged in an orientation preference map that has a concentric organization, which is aligned to the center of vision and the optic flow experienced by the mouse. The developmental mechanisms that underlie this functional map remain unclear. Here, we propose that the spatiotemporal properties of sp...
Preprint
Among the different autism spectrum disorders, Fragile X Syndrome (FXS) is the most common inherited cause of mental retardation. Sensory and especially auditory hypersensitivity is a key symptom in patients, which is well mimicked in the Fmr1 -/- mouse model. However, the physiological mechanisms underlying FXS acoustic hypersensitivity in particu...
Preprint
Full-text available
The cerebral cortex receives multiple afferents from the thalamus that segregate by stimulus modality forming cortical maps for each sense. In vision, the primary visual cortex also maps the multiple dimensions of the stimulus in patterns that vary across species for reasons unknown. Here we introduce a general theory of cortical map formation, whi...
Preprint
The superior colliculus (SC) is a midbrain structure that plays important roles in visually guided behaviors. Neurons in the SC receive afferent inputs from retinal ganglion cells (RGC), the output cells of the retina, but how SC neurons integrate RGC activity in vivo is unknown. SC neurons might be driven by strong but sparse retinal inputs, there...
Article
Full-text available
The primary visual cortex of carnivores and primates is dominated by the OFF visual pathway and responds more strongly to dark than light stimuli. Here, we demonstrate that this cortical OFF dominance is modulated by the size and spatial frequency of the stimulus in awake primates and we uncover a main neuronal mechanism underlying this modulation....
Article
Full-text available
Excitatory synaptic input reaches the soma of a cortical excitatory pyramidal neuron via anatomically segregated apical and basal dendrites. In vivo, dendritic inputs are integrated during depolarized network activity, but how network activity affects apical and basal inputs is not understood. Using subcellular two-photon stimulation of Channelrhod...
Article
Full-text available
A defining feature of cortical layer 2/3 excitatory neurons is their sparse activity, often firing in singlets of action potentials. Local inhibitory neurons are thought to play a major role in regulating sparseness, but which cell types are recruited by single excitatory synaptic inputs is unknown. Using multiple, targeted, in vivo whole-cell reco...
Article
Full-text available
The synchronized activity of six layers of cortical neurons is critical for sensory perception and the control of voluntary behavior, but little is known about the synaptic mechanisms of cortical synchrony across layers in behaving animals. We made single and dual whole-cell recordings from the primary somatosensory forepaw cortex in awake mice and...
Article
Full-text available
Neurons in the primary visual cortex are known for responding vigorously but with high variability to classical stimuli such as drifting bars or gratings. By contrast, natural scenes are encoded more efficiently by sparse and temporal precise spiking responses. We used a conductance-based model of the visual system in higher mammals to investigate...
Data
V1 responses to a grating stimulus with simulated eye-movements. (A–E) Same format as Figures 4, 5. (A,B) Spiking and sub threshold responses during the grating + eye-movement stimulus of the same simple cells in vivo (A) and in the model (B) as shown in Figures 4, 5 during the grating and natural stimulus, respectively. Note, the evoked responses...
Data
V1 responses to a dense noise stimulus. (A–E) Same format as Figures 4, 5. (A,B) Spiking and sub threshold responses during the dense noise stimulus in vivo (A) and in the model (B). Note that dense noise evokes both temporally precise (peaks in the raster) and imprecise events (locked to the onset of the stimulus sequence). (C) Response timescales...
Article
The primary visual cortex contains a detailed map of the visual scene, which is represented according to multiple stimulus dimensions including spatial location, ocular dominance and stimulus orientation. The maps for spatial location and ocular dominance arise from the spatial arrangement of thalamic afferent axons in the cortex. However, the orig...
Article
Parallel perception of multiple orientations is essential for identification of patterns and 3-D shapes from texture. While the primary visual cortex of primates and carnivores is organized in columns of neurons that respond to the same orientation preferences, neuronal responses to gratings of preferred orientation can be suppressed when another o...
Article
The unique hues-blue, green, yellow, red-form the fundamental dimensions of opponent-color theories, are considered universal across languages, and provide useful mental representations for structuring color percepts. However, there is no neural evidence for them from neurophysiology or low-level psychophysics. Tapping a higher prelinguistic percep...
Article
Full-text available
Images are processed in the primary visual cortex by neurons that encode different stimulus orientations and spatial phases. In primates and carnivores, neighboring cortical neurons share similar orientation preferences, but spatial phases were thought to be randomly distributed. We discovered a columnar organization for spatial phase in cats that...
Article
Full-text available
Local field potentials (LFPs) have become an important measure of neuronal population activity in the brain and could provide robust signals to guide the implant of visual cortical prosthesis in the future. However, it remains unclear whether LFPs can detect weak cortical responses (e.g., cortical responses to equiluminant color) and whether they h...
Article
Visual information is mediated by two major thalamic pathways that signal light decrements (OFF) and increments (ON) in visual scenes, the OFF pathway being faster than the ON. Here, we demonstrate that this OFF temporal advantage is transferred to visual cortex and has a correlate in human perception. OFF-dominated cortical neurons in cats respond...
Article
Full-text available
Significance Light and dark stimuli are separately processed by ON and OFF channels in retina and thalamus. Although most textbooks assume that ON and OFF visual responses are relatively balanced throughout the visual system, recent studies have identified a pronounced overrepresentation of OFF responses in the cerebral cortex. This recent discover...
Article
Full-text available
In a wide range of studies, the emergence of orientation selectivity in primary visual cortex has been attributed to a complex interaction between feed-forward thalamic input and inhibitory mechanisms at the level of cortex. Although it is well known that layer 4 cortical neurons are highly sensitive to the timing of thalamic inputs, the role of th...
Article
The time course of visual responses is thought to play a major role in visual processing. For example, X and Y thalamic cells in the cat (M and P cells in the primate) have different temporal properties and are presumed to serve different functions. In contrast to X and Y visual pathways, ON and OFF pathways were originally thought to differ only i...
Article
Full-text available
Recordings from local field potentials (LFPs) are becoming increasingly common in research and clinical applications, but we still have a poor understanding of how LFP stimulus selectivity originates from the combined activity of single neurons. Here, we systematically compared the stimulus selectivity of LFP and neighboring single-unit activity (S...
Article
Full-text available
In this article, we present a methodological framework that meets novel requirements emerging from upcoming types of accelerated and highly configurable neuromorphic hardware systems. We describe in detail a device with 45 million programmable and dynamic synapses that is currently under development, and we sketch the conceptual challenges that ari...
Article
Full-text available
Both ongoing and natural stimulus driven neuronal activity are dominated by transients. Selective gating of these transients is mandatory for proper brain function and may, in fact, form the basis of millisecond-fast decision making and action selection. Here we propose that neuronal networks may exploit timing differences between correlated excita...
Conference Paper
In this paper we describe our approach towards highly configurable neuromorphic hardware systems that serve as useful and flexible tools in modeling neuroscience. We utilize a mixed-signal VLSI model that implements a massively accelerated network of spiking neurons, and we describe a novel methodological framework that allows to exploit both the s...
Article
Full-text available
Neurons in the neocortex receive a large number of excitatory and inhibitory synaptic inputs. Excitation and inhibition dynamically balance each other, with inhibition lagging excitation by only few milliseconds. To characterize the functional consequences of such correlated excitation and inhibition, we studied models in which this correlation str...
Conference Paper
We will set up a fully functional system consisting of a custom design hardware framework (Figures 1 and 2) with the neural network chips described in the appended 4-page paper, Section II-A. The framework is connected digitally to a host PC, on which we will run a software that provides the simulator-like, flexible and non-expert usability of the...
Conference Paper
Trends in programming language development and adoption point to Python as the high-level systems integration language of choice. Python leverages a vast developer-base external to the Neuroscience community, and promises leaps in model complexity and maintainability to any neural simulator which adopts it. As such, Python is emerging as the de fac...
Article
Full-text available
Neurons receive a large number of excitatory and inhibitory synaptic inputs whose temporal interplay determines the spiking behavior. On average, excitation and inhibition balance each other, such that spikes are elicited by fluctuations. In addition, it has been shown in vivo that excitation and inhibition are correlated, with inhibition lagging e...
Article
Full-text available
Computational neuroscience has produced a diversity of software for simulations of networks of spiking neurons, with both negative and positive consequences. On the one hand, each simulator uses its own programming or configuration language, leading to considerable difficulty in porting models from one simulator to another. This impedes communicati...
Article
Full-text available
Sensory input enters the cortex via the thalamocortical (TC) projection, where it elicits large postsynaptic poten-tials in layer 4 neurons [1]. Interestingly, the TC connec-tions account for only ~15% of synapses onto these neurons. It has been therefore controversially discussed how thalamic input can drive the cortex. Strong TC syn-apses have be...
Conference Paper
Full-text available
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Article
Recently, a quantitative wiring diagram for the local neuronal network of cat visual cortex was described [T. Binzegger, R.J. Douglas, K.A.C. Martin, A quantitative map of the circuit of the cat primary visual cortex, J. Neurosci. 39 (24) (2004) 8441–8453.] giving the first complete estimate of synaptic connectivity among various types of neurons i...
Article
We introduce and utilize a novel methodological framework for the unified setup, execution and analysis of cortical network experiments on both a neuromorphic hardware device and a software simulator. In order to be able to quantitatively compare data from both domains, we developed hardware calibration and parameter mapping procedures that allow f...

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