Biology subjects

Petersen, P. C.

Publications and source records attributed to Petersen, P. C..

4 recordsLinked to original sources

bioRxiv2022

Brain temperature affects quantitative features of hippocampal sharp wave ripples

Biochemical mechanisms are temperature-dependent. Brain temperature shows wide variations across brain states, and such changes may explain quantitative changes in network oscillations. Here we report on the coupling of various hippocampal sharp wave ripple features to brain temperature. Ripple frequency, occurrence rate and duration correlated with temperature dynamics. By focal manipulation of the brain temperature in the hippocampal CA1 region, we show that ripple frequency can be increased and decreased by local heating and cooling, respectively. Changes of other parameters, such as the rate of SPW-R and ripple duration were not consistently affected. Our findings suggest that brain temperature in the CA1 region plays a leading role in affecting the ripple frequency, whereas other parameters of SPW-Rs may be determined by mechanisms upstream from the CA1 region. These findings illustrate that physiological variations of brain temperature exert important effects on hippocampal circuit operations.

neuroscience↗

bioRxiv2020

CellExplorer: a graphical user interface and standardized pipeline for visualizing and characterizing single neuron features

The large diversity of neuron types of the brain, characterized by a unique set of electrophysiological characteristics, provides the means by which cortical circuits perform complex operations. To quantify, compare, and visualize the functional features of single neurons, we have developed the open-source framework, CellExplorer. It consists of three components: a processing module that calculates standardized physiological metrics, performs neuron type classification and detects putative monosynaptic connections, a flexible data structure, and a powerful graphical interface. The graphical interface makes it possible to explore any combination of pre-computed features at the speed of a mouse click. The CellExplorer framework allows users to process and relate their data to a growing collection of "ground truth" neurons from different genetic lines, as well as to tens of thousands of single neurons collected across our labs. We believe CellExplorer will accelerate the linking of physiological properties of single neurons in the intact brain to genetically identified types.

neuroscience↗

bioRxiv2019

Cooling of medial septum reveals theta phase lag coordination of hippocampal cell assemblies

Hippocampal theta oscillations coordinate neuronal firing to support memory and spatial navigation. The medial septum (MS) is critical in theta generation by two possible mechanisms: either a unitary pacemaker timing signal is imposed on the hippocampal system or it may assist in organizing target subcircuits within the phase space of theta oscillations. We used temperature manipulation of the MS to test these models. Cooling of the MS reduced both theta frequency and power, was associated with enhanced incidence of errors in a spatial navigation task but did not affect spatial correlates of neurons. MS cooling decreased theta frequency oscillations of place cells, reduced distance-time compression but preserved distance-phase compression of place field sequences within the theta cycle. Thus, septal computation contributes not only theta pacing but is also critical for sustaining precise theta phase-coordination of cell assemblies in the hippocampus.

neuroscience↗

bioRxiv2018

Decoupling of timescales reveals sparse convergent CPG network in the adult spinal cord

During the generation of rhythmic movements, most spinal neurons receive an oscillatory synaptic drive. The neuronal architecture underlying this drive is unknown, and the corresponding network size and sparseness have not yet been addressed. If the input originates from a small central pattern generator (CPG) with dense divergent connectivity, it will induce correlated input to all receiving neurons, while sparse convergent wiring will induce a weak correlation, if any. Here, we use pairwise recordings of spinal neurons to measure synaptic correlations and thus infer the wiring architecture qualitatively. A strong correlation on a slow timescale implies functional relatedness and a common source, which will also cause correlation on fast timescale due to shared synaptic connections. However, we consistently find marginal coupling between slow and fast correlations regardless of neuronal identity. This suggests either sparse convergent connectivity or a CPG network with recurrent inhibition that actively decorrelates common input.

neuroscience↗