1. Sensory Gating, Anxiety, Seizures, and Pain
Neuronal
Networks
Laboratory
University of Nottingham Medical School
Neuronal Networks Laboratory
Using Plexon at Nottingham:
Sensory Gating, Anxiety, Seizures, and Pain
Dr Rob Mason
School of Biomedical Sciences
University of Nottingham Medical School

2. Neuronal
Networks
Laboratory
Talk Format
Brief overview of what we have been studying using Plexon system(s) at Nottingham
Indicate on route some hardware developments
& signal processing / analysis approaches we use
schizophrenia – sensory gating
epilepsy
anxiety
pain

3. Multiple Electrode Recordings in vivo
simultaneous multichannel spike & field potential recording
64-channel MAP system
32-channel MAP system – with CinePlex for behavioural studies
64-channel Recorder system
16-channel Recorder system
used MAP & Recorder for in vitro MEA studies with brain slices & neuronal cultures

4. LAB TEAM epilepsy Ben Coomber [Dr Mike O’Donoghue] Clare Roe
Neuronal
Networks
Laboratory
LAB TEAM
epilepsy Ben Coomber [Dr Mike O’Donoghue]
Clare Roe
schizophrenia Dr Jill Suckling [Prof CA Marsden]
Dr Dissanayake
anxiety Dr Carl Stevenson [Prof CA Marsden]
pain Dr Steve Elmes [Dr V Chapman]
rodent USVs Beth Tunstall [Dr S Beckett]
data analysis Margarita Zachariou [Dr S Coombes / Dr M Owen]
[Mathematics Dept]
Dr David Halliday (University of York)
Prof D Auer (fMRI / phMRI)

5. LAB EXPERIMENTAL DIRECTIONS medial Pre-Frontal Cortex
mPFCx interconnectivity & functional context – in vivo studies
maternal separation
- depression
circadian
- affective states
sensory gating
- schizophrenia
- epilepsy
USVs
medial Pre-Frontal Cortex
Amygdala
nucleus Accumbens
Hippocampus
SCN
Contralateral
mPFC
VTA
- drugs of abuse
PVt

6. Systemic pharmacological manipulation
Neuronal
Networks
Laboratory
Dual site recordings
VTA - mPFC
hippocampus - mPFC
amygdala - mPFC
mPFC - mPFC
Systemic pharmacological manipulation
Local pharmacological manipulation
“injec-trode”
integrated microiontophoresis with recording array
Electrical stimulation
Independent electrode array microdrive
Anaesthetised & awake-behaving preparations

7. Project #1: Schizophrenia
Neuronal
Networks
Laboratory
University of Nottingham Medical School
Neuronal Networks Laboratory
Project #1: Schizophrenia
auditory-evoked sensory gating
effects of PCP / ketamine - model
effects of social isolation - model

8. Schizophrenia - VTA/mPFCx dual-site recordings
Prussian Blue reaction - locate recording site(s) - histology
ventral tegmental area - VTA
medial prefrontal cortex - mPFC

9. Dual site recording: pre-frontal cortical / VTA recording
multiple single-units & LFPs
1 mV
5 s
VTA
cells
PFC
LFP 1 8 7
Neurone #
Matlab scripts for off-line characterisation unit spike waveforms & LFPs

10. Local application of drugs – “injec-trode”
Explore connectivity between PFC and VTA -
e.g. local application of drug (e.g. glutamate)
to VTA to drive mPFC
Local application of drugs – “injec-trode”
10s
Extra-VTA
PFC
Extra-VTA LFP
PFC LFP
50 nl Glutamate (100 mM)
Electrode headstage
Tubing attached to Hamilton syringe
Electrode tips
Cannula tip

11. Sensory gating in hippocampus: A model for schizophrenia ?
Neuronal
Networks
Laboratory
Sensory gating in hippocampus: A model for schizophrenia ?
Sensory gating: mechanism(s) by which irrelevant sensory information is filtered – enables efficient information processing
Auditory Conditioning-Test paradigm: measures reduction in auditory-evoked response produced by Test stimulus following a Conditioning stimulus
Stimuli: 3kHz sine-wave / 10ms duration / presented 500ms apart / 80-90dB
human P50 wave = rat N40 component
Gating absent in - schizophrenic patients (& near family members)
- normal human volunteers given PCP / amphetamine
- rats given PCP / amphetamine

12. Hippocampal CA3 - auditory-evoked unit & LFP activity1s
LFP2 averaged
128 trials
Units
LFPs
event
tone
- 128
- 1
Trial # s Cs Ts mV
N40
Averaged
LFP
T/C ratio = 50%

13. Single-unit PSTHs ‘ rasters histograms - gating rats
dentate gyrus
CA3 region
Single-unit PSTHs ‘ rasters histograms - gating rats
Unit 1
Unit 2
Unit 3
Unit 4
Spike raster
PSTH
LFP
LFP trial
raster

14. Hippocampal CA3 auditory-evoked unit & LFP activity
Effects of PCP (1mg/kg i.p.)  attenuates/abolishes sensory gating
Basal [128 trials]
T/C ratio = 32%
45mins after PCP
T/C ratio = 66% 1
Trail #
128

15. University of Nottingham Medical School Neuronal Networks Laboratory
Project #2: Epilepsy
kainate-induced epileptiform activity – TLE
functional network interactions - hippocampus  mPFC
electrical stimulation – perforant pathway
role of endocannibnoid system – CB1R pharmacology

16. Kainate-induced epileptiform activity – dual recording hippocampus & mPFC
HippL
HippM
Basal firing
KA-induced firing (10mg kg-1, i.p.) 2s
hippocampus
mPFC

17. Hippocampal-mPFC – functional connectivity
Burst analysis – Synchrony index - Cross-correlation – coherence - PDC
mPFC
Hipp
HIPP
Ref unit
mPFC
Hippocampus
unit 3H
unit 1H
unit 2H

18. PDC Analysis – Unit populations
Identify direction of activity between hippocampus and mPFC - PDC applied: technique with potential to reveal the neuronal ensemble drive direction.
Note: the magnitude of the classical coherence gives no information about directional connectivity, but its phase may do so. KA

19. PDC Analysis – LFPs
Representative PDC plot between LFPs recorded from 3 electrodes in both
mPFC (AD01-08)
hippocampus (AD10 to AD16 = medial to lateral electrodes).
TIME FRAME #
Hippocampus
mPFC
Red boxes highlight PDC between brain regions – suggesting the predominant flow is from mPFC to hippocampus
Green boxes highlight that the predominant flow within hippocampus is from lateral to medial.

20. LFPanalyser suite 2006 – custom Matlab script
Basal (pre-KA challenge) - hippocampus

21. 45min post-KA - hippocampus
LFPanalyser suite 2006

22. LFPanalyser suite 2006

23. % Power Distribution
Basal
45min Post-KA
LFPanalyser suite 2006

24. Project #3: Nociception & pain management
Neuronal
Networks
Laboratory
University of Nottingham Medical School
Neuronal Networks Laboratory
Project #3:
Nociception & pain management
dual spinal cord / supraspinal recording
Role of endocannabinoid system in normal physiology and pain (e.g. neuropathic) states

25. Mechanically-evoked response in somatosensory thalamus (VPM)
innocuous (7g) stimulation
noxious (65g) stimulation

26. Project #4: Affective state
Neuronal
Networks
Laboratory
University of Nottingham Medical School
Neuronal Networks Laboratory
Project #4: Affective state
Cortico-limibic network interactions
anxiety
effects of maternal separation
pharmacologically-induced (e.g. FG-7142) anxiety
behavioural sequalae
rodent ultrasound vocalisations

27. nucleus accumbens – mPFC
Role of nuc accumbens in USV-mediated Behaviours
nucleus accumbens / basolateral amygdala - mPFCx functional connectivity
nucleus accumbens – mPFC
Rat ultrasound vocalisations (USVs) & affective state
Neuronal
Networks
Laboratory
50kHz
22kHz
Time (s)
Frequency (kHz)
~22 kHz calls
- aversive stimuli (call Type G)
~50 kHz calls
- rewarding stimuli (Types A-F)

28. Combined unit / LFP with USV / behavioural recording
USV call start time
unit activity
- nuc accumbens
USV Recorder input
Behavioural data
Local Field Potential (LFP)
Spectrogram
of specific calls [AviSoft]

29. Multiple Electrode Recordings in vivo
simultaneous multichannel spike / field potential / behavioural recording
Video camera
CinePlex system

30. Behavioural Electrophysiology II
Neuronal
Networks
Laboratory
Behavioural Electrophysiology II
Circular arena recording using CinePlex
Movie - rat HopScotch: 8-microwire array in nuc. accumbens - 6 weeks post implant
Recorded
video
Neural data

31. University of Nottingham Medical School Neuronal Networks Laboratory
That’s all folks
Lab web site