Biology subjects

Newey, S. E.

Publications and source records attributed to Newey, S. E..

5 recordsLinked to original sources

bioRxiv2024

Local cortical inhibitory subnetworks are shaped by pyramidal neuron progenitor type

The degree to which cortical neurons share inhibitory synaptic input determines their co-activity within a network. However, the principles by which inhibition is shared between neurons are not known. Here we combine in utero labeling with in vivo two-photon targeted patch-clamp recordings in mature cortex to reveal that a layer 2/3 (L2/3) pyramidal neurons local inhibitory input reflects the embryonic progenitor type from which the neuron is born. In contrast to neighboring neurons, pyramidal neurons derived from intermediate progenitors receive synaptic inhibition that is weakly coupled to local network activity. The underlying mechanisms do not depend upon the amount of inhibitory input received from different interneuron subclasses. Rather, progenitor type defines how much inhibitory input a neuron shares with its neighbors, which is reflected in how individual interneurons target pyramidal neurons according to progenitor type. These findings reveal new significance for progenitor diversity and identify ontogenetic origins of fine-scale inhibitory cortical subnetworks.

neuroscience↗

bioRxiv2023

All-optical reporting of chloride ion driving force in the nervous system.

Ionic driving forces provide the net electromotive force for ion movement across receptors, channels, and transporters, and are a fundamental property of all cells. In the brain for example, fast synaptic inhibition is mediated by chloride permeable GABAA receptors, and single-cell intracellular recordings have been the only method for estimating driving forces across these receptors (DFGABAA). Here we present a new tool for quantifying inhibitory receptor driving force named ORCHID: all-Optical Reporting of CHloride Ion Driving force. We demonstrate ORCHIDs ability to provide accurate, high-throughput measurements of resting and dynamic DFGABAA from genetically targeted cell types over multiple timescales. ORCHID confirms theoretical predictions about the biophysical mechanisms that establish DFGABAA, reveals novel differences in DFGABAA between neurons and astrocytes, and affords the first in vivo measurements of intact DFGABAA. This work extends our understanding of inhibitory synaptic transmission and establishes a precedent for all-optical methods to assess ionic driving forces.

neuroscience↗

bioRxiv2022

Cortical integration of higher-order thalamic inputs is lineage-dependent

Primary sensory cortex receives and integrates inputs from first-order and higher-order thalamic nuclei. First-order inputs convey sensory information from the periphery and exhibit simple response properties, whereas higher-order inputs exhibit more complex response properties, provide contextual feedback, and can modulate first-order inputs. Here we show that the way in which cortical neurons integrate these thalamic inputs, reflects the progenitor cell from which the cortical neurons derive. Within layer 4 of mouse primary somatosensory cortex, excitatory neurons that derive from apical intermediate progenitors exhibit multi-whisker response properties and receive higher-order thalamic input, in a manner consistent with their dendritic morphology. These properties depend upon the expression levels of the transcription factor Lhx2, which when increased, abolishes the higher-order properties of apical intermediate progenitor-derived neurons, and disrupts the induction of sensory-evoked plasticity. These data reveal a lineage-dependent mechanism that establishes the integration and functional contribution of higher-order thalamic inputs within cortex.

neuroscience↗

bioRxiv2018

Excitatory GABAergic signalling is associated with acquired benzodiazepine resistance in status epilepticus

Status epilepticus (SE) is defined as a state of unrelenting seizure activity. It is associated with a rapidly rising mortality rate, and thus constitutes a medical emergency. Benzodiazepines, which act as positive modulators of chloride (Cl-) permeable GABAA receptors, are indicated as the first line of treatment, but this is ineffective in many cases. We found that 48% of children presenting with SE were unresponsive to benzodiazepine treatment, and critically, that the duration of SE at the time of treatment is an important predictor of non-responsiveness. We therefore investigated the cellular mechanisms that underlie acquired benzodiazepine resistance, using rodent organotypic brain slices. Removing Mg2+ ions leads to an evolving pattern of epileptiform activity, and eventually to a persistent state of repetitive discharges that strongly resembles clinical EEG recordings of SE. We show that the persistent SE-like activity is associated with a reduction in GABAA receptor conductance and Cl- extrusion capability. We explored the effect on intraneuronal Cl- using both gramicidin, perforated-patch clamp recordings and Cl- imaging. This showed that during SE-like activity, reduced Cl- extrusion capacity was further exacerbated by activity-dependent Cl- loading, resulting in a persistently high intraneuronal Cl-. Consistent with these results, we found that optogenetic stimulation of GABAergic interneurons in the SE-like state, actually enhanced epileptiform activity in a GABAAR dependent manner. Together our findings describe a novel potential mechanism underlying benzodiazepine-resistant SE, with relevance to how this life-threatening condition should be managed in the clinic.

neuroscience↗

bioRxiv2018

Fine-scale excitatory cortical circuits reflect embryonic progenitor pools

Introductory paragraph Introductory paragraph Main text Animals In utero electroporation Intrathalamic injections Slice preparation and recording... Stimulation and recording... Analysis of recordings Histological analyses Statistics Methods Author Contributions References The mammalian neocortex is characterised by precise patterns of synaptic connections, which dictate how information flows through cortical circuits. The degree of convergence and divergence of excitatory information results from highly non-random, short-range and long-range glutamatergic synaptic connections1-11. Previous seminal work has shown that c ...

neuroscience↗