לוח שנה משולב

The plasticity of the brain plays a key role in shaping our behavior, learning and memory. It is well known that plasticity is associated with alteration in synaptic strength and efficacy. Some of these effects correlate with changes in the levels of synaptic proteins. However, the implications of genetic alteration in synaptic proteins on the network activity of neurons are not known. We examine the effect of DOC2B, a synaptic neuronal Ca2+ sensor that is known for its ability to enhance synaptic transmission, on neuronal network activity. For that purpose we use MicroElectrode Array (MEA) technology to simultaneously record action potentials from multiple neurons in ex vivo neuronal network. Networks grown on MEA plates exhibit a repeated pattern of synchronized network-wide spiking activity (network burst) separated by periods of reduced activity. At the single-neuron level, DOC2B increased the frequency of spontaneous neurotransmitter release. However, its effect at the network level was restricted to the network bursts and was reflected as an increase in the number of spikes and the number of active neurons throughout the network burst, while surprisingly there was no effect on inter-burst spiking activity. In addition, DOC2B enhanced the number of full-blown network bursts, suggesting an impact on the input/output ratio of synaptic transmission. Further analysis suggested DOC2B’s activity was augmented during neuronal bursts and enhanced spontaneous and asynchronous release. This can increase the neuron’s sensitivity to incoming EPSPs and the number of spikes in the network burst. Additionally, our experiments support the hypothesis that DOC2B efficiently enhances synaptic refilling. Hence, this work shows that the changes at the network level complemented our knowledge on the cellular activity of DOC2B and suggests a role for DOC2B in shaping the firing properties of highly active neuronal networks.

This workshop will cover the theory and basic methods used in phylogenetic inference. The majority of the workshop will be on the theory behind phylogenetic analysis, mixed in with practical applications that are derived from the theory. It will not go in depth on any particular program, rather cover the different types of algorithms available, and examples will be shown

Abstract:
Adapting coding is ambiguous - the same response may have a different meaning depending on the history and the context of the stimulus. Using intracellular recordings in the brainstem of rats we found that changing the intensity of tactile stimulation has an opposite effect on the degree of adaptation in two major brainstem somatosensory subnuclei. Interestingly, using single cell and LFP recordings we found strong ‘signatures’ for these adaptation patterns in different cortical layers in a manner that was exactly predicted from previous in-vitro studies. We suggest that converging inputs from these ascending pathways in the cortex may partially solve the ambiguity of adapting coding. In the second part I will describe how the balance between excitation and inhibition is affected by adapting stimulation and how it is modulated by different cortical states. In particular, I will show that adaptation skews the balance toward excitation and that unexpectedly this process can facilitate cortical response to subsequent stimulation. In addition, by manipulating the depth of anesthesia we found that slow brain activity is characterized by enhanced inhibitory inputs but surprisingly without a significant effect on the magnitude of excitation, which suggests that despite the recurrent connectivity in the cortex some level of decoupling exists between cortical excitation and inhibition.