Topic: synapses

Binary and analog variation of synapses between cortical pyramidal neurons

n the neurosciences the need for some 'overarching' theory is sometimes expressed, but it is not always obvious what is meant by this. One can perhaps agree that in modern science observation and experimentation is normally complemented by 'theory', i.e. the development of theoretical concepts that help guiding and evaluating experiments and measurements. A deeper discussion of 'brain theory' will require the clarification of some further distictions, in particular: theory vs. model and brain research (and its theory) vs. neuroscience. Other questions are: Does a theory require mathematics? Or

A fundamental problem in neuroscience is understanding how the properties of individual neurons and synapses contribute to neuronal circuit dynamics and behavior. In recent years we have done both computational and experimental studies that demonstrate that the same physiological output can arise from multiple, degenerate solutions, and that individual animals with similar behavior can nonetheless have quite different sets of underlying circuit parameters. Most recently, we have been studying the resilience of individual animals to perturbations such as temperature and high potassium concent

Sam Gershman discusses molecular accounts of memory and how they relate to the dominant view of storage through changes in synapses.

The complex morphology of neurons, with synapses located hundreds of microns from the cell body, necessitates the localization of important cell biological machines, including ribosomes, within dendrites and axons. Local translation of mRNAs is important for the function and plasticity of synapses. Using advanced sequencing and imaging techniques we have updated our understanding of the local transcriptome and identified the local translatome- identifying over 800 transcripts for which local translation is the dominant source of protein. In addition, we have explored the unique mechanisms neur

Connections between nerve cells called synapses are the fundamental units of communication and information processing in the brain. The accurate wiring of neurons through synapses into neural networks or circuits is essential for brain organization. Neuronal networks are sculpted and refined throughout life by constant adjustment of the strength of synaptic communication by neuronal activity, a process known as synaptic plasticity. Deficits in the development or plasticity of synapses underlie various neuropsychiatric disorders, including autism, schizophrenia and intellectual disability. The

In the adult brain, synapses are tightly enwrapped by lattices of extracellular matrix that consist of extremely long-lived molecules. These lattices are deemed to stabilize synapses, restrict the reorganization of their transmission machinery, and prevent them from undergoing structural or morphological changes. At the same time, they are expected to retain some degree of flexibility to permit occasional events of synaptic plasticity. The recent understanding that structural changes to synapses are significantly more frequent than previously assumed (occurring even on a timescale of minutes)

Survival is predicated on the ability of an organism to respond to stress. The reliability of this response is ensured by a synaptic architecture that is relatively inflexible (i.e. hard-wired). Our work has shown that in naive animals, synapses on CRH neurons in the paraventricular nucleus of the hypothalamus are very reluctant to modification. If animals are stressed, however, these synapses become willing to learn. This seminar will focus on mechanisms linking acute stress to metaplastic changes at glutamate synapses, and also show how stress, and these synaptic changes can be transmitted

Synaptic inputs on cortical dendrites are organized with remarkable subcellular precision at the micron level. This organization emerges during early postnatal development through patterned spontaneous activity and manifests both locally where synapses with similar functional properties are clustered, and globally along the axis from dendrite to soma. Recent experiments reveal species-specific differences in the local and global synaptic organization in mouse, ferret and macaque visual cortex. I will present a computational framework that implements functional and structural plasticity from sp

Neurons use a variety of strategies, including local protein synthesis and pre-established protein pools inside dendrites, to maintain the dynamic proteome requirements for appropriate synaptic activity. While certain proteins have local mRNA that allows for on-demand synthesis at the synapse, the vast majority do not. This poses an important question: how can these proteins manage their copy number without boosting the synthesis rate locally? This study looks into the hypothesis that the amount of the protein pool in dendrites corresponds with the presence or lack of dendritic mRNA for local

Neural networks need to continuously adapt their representations to survive in a constantly changing environment. To test behavioral flexibility reversal learning paradigms are often used [1]. This flexible adaptation of entrained representations can be mediated by unlearning and forgetting [2]. One possible factor for passive forgetting could be the spontaneous remodeling of neuronal circuitry [3]. Acknowledging that previous studies have presented conflicting views on the effects of forgetting during reversal learning, we hypothesize two potential scenarios: Hypothesis I ('Reusing'): Reusing

Left-right asymmetry is a fundamental feature of higher-order brain structure and function. Within the mouse hippocampus, properties of synapses between pyramidal cells depend on the hemispheric origin of presynaptic inputs. In the CA3-CA1 connection, right-input synapses in stratum radiatum have larger postsynaptic density (PSD) and higher perforation ratio, expressing lower NR2B subunit density, than left-input synapses. The major histocompatibility complex class I (MHCI) and Paired immunoglobulin-like receptor B (PirB) contribute to this asymmetry, suggesting potential trans-synaptic signal