Past events

Insects are an inexhaustible source for scientists who desire to inspire ideas, processes, structures and functions from biology and implement them into engineering, specifically those interested in locomotion and in the improvement of robot mobility. Novel insights are offered based on a collaborative and combined approach that includes high-speed video monitoring of behavior, electrophysiological recordings of nerves and muscles activity, mathematical modeling and computer simulations. An overview will be presented of several different research projects focusing on cockroach running, caterpillar crawling (soft robotics), locust jumping, flight (remote control), and swarming.

Much of what we know about how neurons interact and form ensemble activity patterns comes from recordings in cell cultures, brain slices, and anesthetized animals, yet dynamics in the intact brain of a behaving animal might differ. I will describe an approach to the study of local circuit dynamics in freely-moving animals, namely the combination of high-density extracellular recordings coupled with multi-site/multi-color optogenetic stimulation, combined with in-vivo pharmacology. This approach, applied to the rodent neocortex and hippocampus, yielded surprising insight into mechanisms of multiple phenomena, including spiking regime resonance, the generation of high-frequency oscillations, and spike phase precession.

Retinal degenerative diseases, such as Retinitis Pigmentosa (RP) and Age related Macular Degeneration (AMD), lead to loss of sight due to degeneration of photoreceptors, yet the inner retinal neurons which process the visual signals and relay them to the brain are relatively well preserved. Patterned electrical stimulation of the inner retinal neurons can elicit patterned visual perception, thereby restoring sight to some degree, as was demonstrated in recent clinical trials. However, current RF-powered implants require bulky electronics and trans-scleral cables, making implantation very complex and prone to failures. Even more importantly, low visual acuity achieved with the current implants limits their applicability to very small fraction of patients. We have developed a wireless photovoltaic retinal prosthesis, in which camera-captured images are projected onto the retina using pulsed near-IR light. Each pixel in the subretinal implant directly converts pulsed light into local electric current to stimulate the nearby inner retinal neurons. Implants with pixel sizes of 280, 140 and 70µm were successfully implanted in the subretinal space of wild type and degenerate rats, and elicited robust cortical responses (eVEP) upon stimulation with NIR light. Amplitude of the eVEP increased with peak irradiance and pulse duration, and decreased with frequency in the range of 2-20Hz, similar to the visible light response. Modular design of the arrays allows scalability to a large number of pixels, and combined with the ease of implantation, offers a promising approach to restoration of sight in patients blinded by retinal degenerative diseases. Activation of the retinal bipolar cells by the implant makes our model a unique tool for studying retinal circuitry by comparing the response to stimuli elicited by the subretinal implant to those naturally elicited by visible light. I will discuss our novel approach to quantitative assessment of the visual acuity provided by the implant, as well as some unique aspects of prosthetic vision, such as stroboscopic stimulation. The theoretical and practical limits of visual acuity will be discussed along with future directions for restoration of sight to the blind.

: I will discuss how sensory information is represented and utilized in the dorsolateral prefrontal cortex (DLPFC) during memory for visual motion tasks. During such tasks, monkeys compare either directions or speeds of two sequential motion stimuli separated by a delay and report whether a current stimulus is the same or different from another held in working memory. We analyzed spiking activity in DLPFC during such tasks, identifying putative local interneurons and putative pyramidal projection neurons, a likely source of top-down influences DLPFC may be exerting on upstream sensory neurons. This analysis revealed that neurons of both types are selective for the speed and the direction of motion, with tuning reminiscent of that recorded in the motion processing area MT. Throughout the memory delay, many DLPFC neurons showed anticipatory rate modulations as well as transient periods of activity reflecting the preceding stimulus, and this activity was represented primarily by the putative pyramidal neurons. During the comparison stimulus, responses of both cell types showed modulation by the remembered stimulus and their activity was highly predictive of the animals’ behavioral report. The similarity in the way DLPFC neurons represent different sensory dimensions provide evidence for the existence of generalized mechanisms in the DLPFC sub-serving all stages of sensory working memory tasks, shedding light on top-down influences this region may be providing to the upstream sensory neurons during such tasks.