1. Dual voltage recordings were made from pairs of adjacent, synaptically connected thick tufted layer 5 pyramidal neurones in brain slices young rat (14‐16 days) somatosensory cortex to examine the physiological properties unitary EPSPs. Pre‐ and postsynaptic filled with biocytin examined light electron microscope quantify morphology axonal dendritic arbors number location synaptic contacts on target neurone. 2. In 138 connections between 96 (70%) unidirectional 42 (30%) bidirectional. The...

Action potential propagation links information processing in different regions of the dendritic tree. To examine contribution morphology to efficacy propagation, simulations were performed detailed reconstructions eight neuronal types. With identical complements voltage-gated channels, morphologies exhibit distinct patterns propagation. Remarkably, range backpropagation efficacies observed experimentally can be reproduced by variations alone. Dendritic geometry also determines extent which...

Action potentials in nonmyelinated axons are considered to contribute substantially activity-dependent brain metabolism. Here we show that fast Na+ current decay and delayed K+ onset during action mossy fibers of the rat hippocampus minimize overlap their respective ion fluxes. This results total influx associated energy demand per potential only 1.3 times theoretical minimum, contrast factor 4 used previous budget calculations for neural activity. Analysis ionic conductance parameters...

Whole‐cell voltage recordings were made in vivo from subsequently reconstructed pyramidal neurons ( n = 30 ) layer 3 (L3) and 2 (L2) of the barrel cortex urethane‐anaesthetised rats. Average resting membrane potentials well below (15−40 mV) action potential (AP) initiation threshold. The average spontaneous AP activity (0.068 ± 0.22 APs s −1 was low. Principal whisker (PW) deflections evoked postsynaptic (PSPs) almost all cells a PW column but (0.031 0.056 per stimulus 6 deg deflection) low...

1 Simultaneous dendritic and somatic patch-clamp recordings were made from Purkinje cells in cerebellar slices 12- to 21-day-old rats. Voltage responses current impulses injected via either the or pipette obtained presence of selective Ih blocker ZD 7288 blockers spontaneous synaptic input. Neurons filled with biocytin for subsequent morphological reconstruction. 2 Four neurons reconstructed converted into detailed compartmental models. The specific membrane capacitance (Cm), resistance (Rm)...

Neurons display a variety of complex dendritic morphologies even within the same class. We examined relationship between arborization and coupling somatic action potential (AP) initiation sites in layer 5 (L5) neocortical pyramidal neurons. Coupling was defined as relative reduction threshold for calcium AP due to coincident back-propagating AP. Simulations based on reconstructions biocytin-filled cells showed that addition oblique branches main apical dendrite close proximity soma (d < 140...

We have investigated the dendritic and axonal morphology of connected pairs L4 spiny neurons L2/3 pyramidal cells in rat barrel cortex. The 'projection' field axons layers 2/3, 4 5 has a width 400–500 μm thereby defining an anatomical barrel-column. In layer averaged together with 'receptive' form mostly column-restricted L4-to-L2/3 'innervation domain' that extends 300–400 includes basal dendrites. innervation domain single neuron contacts ~300–400 while L4-to-L4 it ~200 other neurons....

Defining the rules governing synaptic connectivity is key to formulating theories of neural circuit function. Interneurons can be connected by both electrical and chemical synapses, but organization interaction these two complementary microcircuits unknown. By recording from multiple molecular layer interneurons in cerebellar cortex, we reveal specific, nonrandom patterns GABAergic interneuron networks. Both networks contain clustered motifs show specific overlap between them. Chemical...

Many theories of brain function propose that activity in sparse subsets neurons underlies perception and action. To place a lower bound on the amount neural can be perceived, we used an all-optical approach to drive behaviour with targeted two-photon optogenetic activation small ensembles L2/3 pyramidal mouse barrel cortex while simultaneously recording local network calcium imaging. By precisely titrating number stimulated, demonstrate for cortical is ~14 neurons. We find steep sigmoidal...

Significance An active pyramidal cell model, constrained by physiological and anatomical data, was used to simulate dendritic integration in vivo. The model shows that small numbers of strong excitatory synapses can trigger Na + NMDA spikes. Moreover, only a few spikes are sufficient drive single output action potential. As consequence, as 1% the synaptic inputs neuron determine tuning somatic These results suggest help make sensory representations more efficient flexible: they require fewer...

Axons have traditionally been viewed as highly faithful transmitters of action potentials. Recently, however, experimental evidence has accumulated to support the idea that under some circumstances axonal propagation may fail. Cerebellar Purkinje neurons fire highfrequency simple spikes, well bursts spikes in response climbing fiber activation (the "complex spike"). Here we visualized axon individual cells directly investigate relationship between somatic and using simultaneous whole-cell...

We introduce a method that permits faithful extraction of the decay time course synaptic conductance independent dendritic geometry and electrotonic location synapse. The is based on experimental procedure Pearce (1993), consisting series identical somatic voltage jumps repeated at various times relative to onset conductance. progression charge recovered by successive has characteristic shape, which can be described an analytical function sums exponentials. jump was tested with simulations...

The properties of glutamate receptor (GluR) channels in outside‐out patches from the dendrites and somata rat cerebellar Purkinje cells brain slices were studied using fast agonist application techniques. Dendritic isolated 40–130 μ m soma. Outside‐out both responded to with a current which desensitized rapidly nearly completely. Currents evoked by blocked 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), mimicked l ‐α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA), modulated...

Monosynaptic interlaminar connections between spiny stellate cells in layer 4 (L4), the main cortical recipient for thalamic projections, and pyramidal 5A (L5A), one of output layers, were examined anatomically functionally by paired recordings acute brain slices. The somata pairs forming L4-to-L5A located predominantly close to or directly under barrel-septum wall 4. Superposition axon arbors L5A cell dendritic suggested an innervation domain underneath L4 barrel wall. Functionally, high...

Cerebellar Purkinje cells produce two distinct forms of action potential output: simple and complex spikes. Simple spikes occur spontaneously or are driven by parallel fibre input, while activated climbing input. Previous studies indicate that both originate in the axon cells, but precise location where they initiated is unclear. Here we address cerebellar generated. Using extracellular recording voltage-sensitive dye imaging rat mouse show generated proximal axon, 15-20 mum from soma. Once...

The construction of compartmental models neurons involves tuning a set parameters to make the model neuron behave as realistically possible. While parameter space single-compartment or other simple can be exhaustively searched, introduction dendritic geometry causes number balloon. As is daunting and time-consuming task when performed manually, reliable methods for automatically optimizing are desperately needed, only optimized capture behavior real neurons. Here we present three-step...

Purkinje neurons play an important role in cerebellar computation since their axons are the only projection from cortex to deeper structures. They have complex internal dynamics, which allow them fire spontaneously, display bistability, and also be involved network phenomena such as high frequency oscillations travelling waves. cells exhibit type II excitability, can revealed by a discontinuity f-I curves. We show that this excitability mechanism allows efficiently inhibited noise of...

Many GABAergic interneurons are electrically coupled and in vitro can display correlated activity with millisecond precision. However, the mechanisms underlying between vivo unknown. Using dual patch-clamp recordings vivo, we reveal that presence of spontaneous background synaptic activity, cerebellar Golgi cells exhibit robust precision-correlated which is enhanced by sensory stimulation. This precisely results from cooperative action two mechanisms. First, electrical coupling ensures slow...

Molluscan brains are composed of morphologically consistent and functionally interrogable neurons, offering rich opportunities for understanding how neural circuits drive behavior. Nonetheless, detailed component-level CNS maps often lacking, total neuron numbers unknown, organizational principles remain poorly defined, limiting a full systematic characterization circuit operation. Here, we establish an accessible, generalizable approach, harnessing synchrotron X-ray tomography, to rapidly...