High-density recording of DRN neurons in-vivo

Ruairi O’Sullivan, Tran Tran, Alok Joshi, Chandan Behera, KongFatt Wong-Lin, Raquel Pinacho, Judith Schweimer, David Bannerman, Trevor Sharp

Research output: Contribution to conferencePoster

Abstract

The midbrain dorsal raphe nucleus (DRN) contains the majority of the forebrain-projecting 5-
hydroxy-tryptamine (5-HT) neurons in the brain. These neurons are highly heterogenous in terms of
their molecular characteristics, and they interact with multiple types of neighbouring non-5-HT
neurons in ways that are not yet fully documented. One way to understand the functional
implications of this heterogeneity is to collect large-scale data-sets of DRN neural activity and to use
computational methods to help analyse the complex neural circuitry. Here, we commence to collect
such a data-set through high-density multi-site silicon electrode recordings in the DRN.
Recordings (Open Ephys) were made in urethane-anaesthetised mice using a silicon probe
(Cambridge NeuroTech, 32 channels) stereotaxically implanted into the DRN. EEG electrodes (3
channels) were placed bilaterally over the frontal cortex and right occipital cortex to record brain
state. After 1 h of baseline recording, neurons were screened for evidence of 5-HT1A receptormediated
autoinhibition by administration of the selective serotonin reuptake inhibitor citalopram
(10mg/kg i.p.). Recordings were continued for a further 1 h. Raw data from 32 channels were filtered
and single units were identified automatically using Kilosort and verified by manual clustering using
Phy. Spike trains were further analysed using a suite of custom-written Python scripts to reveal spike
waveform characteristics, firing rate and firing regularity. Spike-sorted neurons then underwent
clustering analysis to reveal groups of neurons with similar firing properties.
An initial analysis (~170 neurons) revealed multiple simultaneously recorded neurons (~35
neurons/mouse). Although much diversity in baseline firing properties was evident, clustering
analysis revealed 3 prominent groups of neurons; regular slow firing neurons previously identified as
putative 5-HT containing, irregular slow firing neurons, and fast firing neurons previously identified
as putative GABA containing. Citalopram inhibited all regular slow firing neurons and some irregular
slow firing neurons, while some of the latter were also excited.
Overall, the current high-density in vivo recordings show evidence of heterogeneity in the baseline
properties of DRN neurons as well as heterogeneity in their response to citalopram administration.
Ongoing experiments are expanding the size of the data-set to increase the power of the clustering
analysis and to commence computational analysis of DRN neuron interactions. Future experiments
will incorporate optotagging to aid chemical identification of the principal neuron clusters.

Other

Other19th Meeting of International Society for Serotonin Research
Abbreviated titleISSR 2018
CountryIreland
CityCork
Period15/07/1818/07/18
Internet address

Fingerprint

Neurons
Citalopram
Dorsal Raphe Nucleus
Silicon
Electrodes
Boidae
Occipital Lobe
Urethane
Serotonin Uptake Inhibitors
Frontal Lobe
Prosencephalon
gamma-Aminobutyric Acid
Cluster Analysis
Electroencephalography
Brain

Cite this

O’Sullivan, R., Tran, T., Joshi, A., Behera, C., Wong-Lin, K., Pinacho, R., ... Sharp, T. (2018). High-density recording of DRN neurons in-vivo. Poster session presented at 19th Meeting of International Society for Serotonin Research, Cork, Ireland.
O’Sullivan, Ruairi ; Tran, Tran ; Joshi, Alok ; Behera, Chandan ; Wong-Lin, KongFatt ; Pinacho, Raquel ; Schweimer, Judith ; Bannerman, David ; Sharp, Trevor. / High-density recording of DRN neurons in-vivo. Poster session presented at 19th Meeting of International Society for Serotonin Research, Cork, Ireland.
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title = "High-density recording of DRN neurons in-vivo",
abstract = "The midbrain dorsal raphe nucleus (DRN) contains the majority of the forebrain-projecting 5-hydroxy-tryptamine (5-HT) neurons in the brain. These neurons are highly heterogenous in terms oftheir molecular characteristics, and they interact with multiple types of neighbouring non-5-HTneurons in ways that are not yet fully documented. One way to understand the functionalimplications of this heterogeneity is to collect large-scale data-sets of DRN neural activity and to usecomputational methods to help analyse the complex neural circuitry. Here, we commence to collectsuch a data-set through high-density multi-site silicon electrode recordings in the DRN.Recordings (Open Ephys) were made in urethane-anaesthetised mice using a silicon probe(Cambridge NeuroTech, 32 channels) stereotaxically implanted into the DRN. EEG electrodes (3channels) were placed bilaterally over the frontal cortex and right occipital cortex to record brainstate. After 1 h of baseline recording, neurons were screened for evidence of 5-HT1A receptormediatedautoinhibition by administration of the selective serotonin reuptake inhibitor citalopram(10mg/kg i.p.). Recordings were continued for a further 1 h. Raw data from 32 channels were filteredand single units were identified automatically using Kilosort and verified by manual clustering usingPhy. Spike trains were further analysed using a suite of custom-written Python scripts to reveal spikewaveform characteristics, firing rate and firing regularity. Spike-sorted neurons then underwentclustering analysis to reveal groups of neurons with similar firing properties.An initial analysis (~170 neurons) revealed multiple simultaneously recorded neurons (~35neurons/mouse). Although much diversity in baseline firing properties was evident, clusteringanalysis revealed 3 prominent groups of neurons; regular slow firing neurons previously identified asputative 5-HT containing, irregular slow firing neurons, and fast firing neurons previously identifiedas putative GABA containing. Citalopram inhibited all regular slow firing neurons and some irregularslow firing neurons, while some of the latter were also excited.Overall, the current high-density in vivo recordings show evidence of heterogeneity in the baselineproperties of DRN neurons as well as heterogeneity in their response to citalopram administration.Ongoing experiments are expanding the size of the data-set to increase the power of the clusteringanalysis and to commence computational analysis of DRN neuron interactions. Future experimentswill incorporate optotagging to aid chemical identification of the principal neuron clusters.",
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O’Sullivan, R, Tran, T, Joshi, A, Behera, C, Wong-Lin, K, Pinacho, R, Schweimer, J, Bannerman, D & Sharp, T 2018, 'High-density recording of DRN neurons in-vivo' 19th Meeting of International Society for Serotonin Research, Cork, Ireland, 15/07/18 - 18/07/18, .

High-density recording of DRN neurons in-vivo. / O’Sullivan, Ruairi; Tran, Tran; Joshi, Alok; Behera, Chandan; Wong-Lin, KongFatt; Pinacho, Raquel ; Schweimer, Judith; Bannerman, David ; Sharp, Trevor.

2018. Poster session presented at 19th Meeting of International Society for Serotonin Research, Cork, Ireland.

Research output: Contribution to conferencePoster

TY - CONF

T1 - High-density recording of DRN neurons in-vivo

AU - O’Sullivan, Ruairi

AU - Tran, Tran

AU - Joshi, Alok

AU - Behera, Chandan

AU - Wong-Lin, KongFatt

AU - Pinacho, Raquel

AU - Schweimer, Judith

AU - Bannerman, David

AU - Sharp, Trevor

PY - 2018

Y1 - 2018

N2 - The midbrain dorsal raphe nucleus (DRN) contains the majority of the forebrain-projecting 5-hydroxy-tryptamine (5-HT) neurons in the brain. These neurons are highly heterogenous in terms oftheir molecular characteristics, and they interact with multiple types of neighbouring non-5-HTneurons in ways that are not yet fully documented. One way to understand the functionalimplications of this heterogeneity is to collect large-scale data-sets of DRN neural activity and to usecomputational methods to help analyse the complex neural circuitry. Here, we commence to collectsuch a data-set through high-density multi-site silicon electrode recordings in the DRN.Recordings (Open Ephys) were made in urethane-anaesthetised mice using a silicon probe(Cambridge NeuroTech, 32 channels) stereotaxically implanted into the DRN. EEG electrodes (3channels) were placed bilaterally over the frontal cortex and right occipital cortex to record brainstate. After 1 h of baseline recording, neurons were screened for evidence of 5-HT1A receptormediatedautoinhibition by administration of the selective serotonin reuptake inhibitor citalopram(10mg/kg i.p.). Recordings were continued for a further 1 h. Raw data from 32 channels were filteredand single units were identified automatically using Kilosort and verified by manual clustering usingPhy. Spike trains were further analysed using a suite of custom-written Python scripts to reveal spikewaveform characteristics, firing rate and firing regularity. Spike-sorted neurons then underwentclustering analysis to reveal groups of neurons with similar firing properties.An initial analysis (~170 neurons) revealed multiple simultaneously recorded neurons (~35neurons/mouse). Although much diversity in baseline firing properties was evident, clusteringanalysis revealed 3 prominent groups of neurons; regular slow firing neurons previously identified asputative 5-HT containing, irregular slow firing neurons, and fast firing neurons previously identifiedas putative GABA containing. Citalopram inhibited all regular slow firing neurons and some irregularslow firing neurons, while some of the latter were also excited.Overall, the current high-density in vivo recordings show evidence of heterogeneity in the baselineproperties of DRN neurons as well as heterogeneity in their response to citalopram administration.Ongoing experiments are expanding the size of the data-set to increase the power of the clusteringanalysis and to commence computational analysis of DRN neuron interactions. Future experimentswill incorporate optotagging to aid chemical identification of the principal neuron clusters.

AB - The midbrain dorsal raphe nucleus (DRN) contains the majority of the forebrain-projecting 5-hydroxy-tryptamine (5-HT) neurons in the brain. These neurons are highly heterogenous in terms oftheir molecular characteristics, and they interact with multiple types of neighbouring non-5-HTneurons in ways that are not yet fully documented. One way to understand the functionalimplications of this heterogeneity is to collect large-scale data-sets of DRN neural activity and to usecomputational methods to help analyse the complex neural circuitry. Here, we commence to collectsuch a data-set through high-density multi-site silicon electrode recordings in the DRN.Recordings (Open Ephys) were made in urethane-anaesthetised mice using a silicon probe(Cambridge NeuroTech, 32 channels) stereotaxically implanted into the DRN. EEG electrodes (3channels) were placed bilaterally over the frontal cortex and right occipital cortex to record brainstate. After 1 h of baseline recording, neurons were screened for evidence of 5-HT1A receptormediatedautoinhibition by administration of the selective serotonin reuptake inhibitor citalopram(10mg/kg i.p.). Recordings were continued for a further 1 h. Raw data from 32 channels were filteredand single units were identified automatically using Kilosort and verified by manual clustering usingPhy. Spike trains were further analysed using a suite of custom-written Python scripts to reveal spikewaveform characteristics, firing rate and firing regularity. Spike-sorted neurons then underwentclustering analysis to reveal groups of neurons with similar firing properties.An initial analysis (~170 neurons) revealed multiple simultaneously recorded neurons (~35neurons/mouse). Although much diversity in baseline firing properties was evident, clusteringanalysis revealed 3 prominent groups of neurons; regular slow firing neurons previously identified asputative 5-HT containing, irregular slow firing neurons, and fast firing neurons previously identifiedas putative GABA containing. Citalopram inhibited all regular slow firing neurons and some irregularslow firing neurons, while some of the latter were also excited.Overall, the current high-density in vivo recordings show evidence of heterogeneity in the baselineproperties of DRN neurons as well as heterogeneity in their response to citalopram administration.Ongoing experiments are expanding the size of the data-set to increase the power of the clusteringanalysis and to commence computational analysis of DRN neuron interactions. Future experimentswill incorporate optotagging to aid chemical identification of the principal neuron clusters.

M3 - Poster

ER -

O’Sullivan R, Tran T, Joshi A, Behera C, Wong-Lin K, Pinacho R et al. High-density recording of DRN neurons in-vivo. 2018. Poster session presented at 19th Meeting of International Society for Serotonin Research, Cork, Ireland.