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.

: A longstanding question at the nexus of cognition and neuroscience concerns the distribution of the labor of learning across different brain systems: what are the different ways in which the brain learns? Recent research has focused on the role of the striatum and midbrain dopamine regions in habitual learning of stimulus-reward associations. However, emerging evidence suggests that the hippocampus – widely known for its role in building flexible memories – is also modulated by reward and innervated by dopamine. This raises new hypotheses about the role of the hippocampus in learning, the unique contributions of the hippocampus and the striatum, and the nature of the relationship between them. I will present studies that address these hypotheses using an integrative approach that combines functional imaging (fMRI) in healthy individuals with studies of learning in patients with selective damage to the striatum or the hippocampus. Converging data from these approaches suggests that both the striatum and the hippocampus contribute to learning, with distinct implications for how learned information guides decisions.

Prof. Kleinfeld will present recent work on the control of rhythmic whisking in rodents. These studies bear on the apparent role of breathing as a master clock that drives orofacial actions, establishes a hierarchy of control of orofacial behaviors, and may temporally bind different orofacial inputs.

Academic achievements such as math and reading are key predictors for future success at school, university, and later in life. Additionally, failure in these critical capacities negatively impacts the welfare of society as a whole. Current understanding of the link between high-level cognition, such as math and reading, and the brain has been primarily restricted to understanding the relationship between brain structure or function. At the same time a substantial body of animal and clinical research showing that cortical inhibition and excitation at the molecular or cellular levels play a critical role in efficient information transfer in the brain. It has further been suggested that cortical inhibition and excitation affects cognition in humans. I will present several studies that show how cortical inhibition and excitation are linked to high-level cognitive abilities in the child and adult human brain, and specifically how we can exogenously modulate cortical inhibition and excitation to optimise brain functions and improve cognition in typical and atypical populations. Such a multidisciplinary approach has the potential to bridge the separated strands of current research in psychology and education, system and molecular neuroscience, as well as animal models.

The computational power of single neurons has long been predicted using modelling approaches, but actual experimental examples of how neurons, and in particular their dendrites, can solve computational problems are rare. I will describe experiments using 2-photon glutamate uncaging in vitro, combined with in vivo 2-photon imaging and patch-clamp recording that demonstrate how active dendrites contribute to shaping canonical cortical computations.