Local Field Potential (LFP): Literature ReviewMd Kafiul Islam
Local Field Potential (LFP), recorded from invasive (in-vivo) neural recordings either by surface of cortex (ECoG/iEEG) or from inside the cortex, has gained increased attention alongside with neural spikes for understanding the information processing of brain and thus relating brain dynamics to a particular behavior or disease. The complete understanding of the underlying mechanism of LFP is yet to be discovered, but it's of no doubt that LFP would be the future to understand our brain in a better way.
these slides contain a brief introduction of neurons and its classification as well as details of generation of action potential, resting potential and eletrotonic potential.
Local Field Potential (LFP): Literature ReviewMd Kafiul Islam
Local Field Potential (LFP), recorded from invasive (in-vivo) neural recordings either by surface of cortex (ECoG/iEEG) or from inside the cortex, has gained increased attention alongside with neural spikes for understanding the information processing of brain and thus relating brain dynamics to a particular behavior or disease. The complete understanding of the underlying mechanism of LFP is yet to be discovered, but it's of no doubt that LFP would be the future to understand our brain in a better way.
these slides contain a brief introduction of neurons and its classification as well as details of generation of action potential, resting potential and eletrotonic potential.
this presentation on cellular electrophysiology carry the information of electrical properties of biophysiology in cellular level. i hope it help you all.
this presentation on cellular electrophysiology carry the information of electrical properties of biophysiology in cellular level. i hope it help you all.
This presentation discusses the basic principles governing EEG Rhythm Generation, and discusses the various circuits that generate and maintain cerebral oscillations.
HC sets aside disqualification of MLAs
The Patna High Court has set aside the Bihar Assembly Speaker’s November order, disqualifying four rebel MLAs on the grounds of “anti-party activities” and “voluntary surrender of membership.”
Background:
Four JD(U) MLAs were disqualified from Bihar Assembly for anti-party activities, including cross voting in Rajya Sabha election.
After the MLAs allegedly cross-voted during the Rajya Sabha by-poll in June last, the Speaker on November 1 terminated their membership and divested them of all facilities available to legislators.
The speaker had disqualified them under the provisions of Anti defection law.
The MLAs had challenged the ruling in the High Court.
HC’s observations:
Defection and dissent were not synonymous, and what the MLAs had done during the Rajya Sabha by-poll was “dissent, and it does not come under the anti-defection law.”
The MLAs had faith in the party and did not defect. Isolated act of dissent, and nothing further to add, cannot amount to voluntary surrender of membership.
Automated Quantitative Measures of Forelimb Function in Rats and MiceInsideScientific
During this webinar Drew Sloan, PhD and Seth Hays, PhD discuss automated forelimb tasks for both rats and mice and applications of the quantitative data collected.
These new procedures are advancing discovery in basic neuroscience and offering deeper understanding of motor control and developing therapies for disease models such as traumatic brain injury, spinal cord injury, and Parkinson’s disease.
Dr. Drew Sloan demonstrates typical training and testing protocols for using the Vulintus MotoTrak behavioral system, including Isometric pull, supination and lever press tasks.
Following, Dr. Seth Hays shares his research which has used MotoTrak to investigate neuroplasticity-enhancing therapies for motor dysfunction, specifically looking at vagus nerve stimulation (VNS) as a method to promote plasticity.
Headaches are a commonly misunderstood and often misdiagnosed clinical symptom. There are at least 60 major types of headaches. Before any headache can be successfully treated or controlled, the origin of the headache must be established. Therefore, diagnosis is essential for proper treatment. This presentation outlines the major sources of the single clinical manifestation of "headache," and lends some organization to thinking about these disorders.
Integrating Noninvasive Blood Pressure Monitoring with Human Physiology Measu...InsideScientific
Experts discuss the fundamentals of real-time, beat-to-beat noninvasive blood pressure (NIBP) monitoring and present new research capabilities enabled through the integration of NIBP technology and physiological recording systems.
In this webinar sponsored by BIOPAC Systems and CNSystems, Frazer Findlay and Walter Habenbacher discuss study design and demonstrate correct equipment set up and operation when recording NIBP with additional physiological signals. Specifically, Mr. Habenbacher explains the application of the NIBP100D-HD to measure noninvasive continuous blood pressure. He demonstrates setup & measurement and shows how scientific findings can benefit your research with advanced hemodynamic monitoring.
Following, Mr. Findlay demonstrates how to interface the NIBP100D Continuous Noninvasive Blood Pressure Monitor with the BIOPAC MP160 Data Acquisition and Analysis System and simultaneously recorded measurements of NIBP, ECG and respiration. In addition, Mr. Findlay discusses important data analysis processes such as computing cardiac output and stroke volume, and demonstrates how scientists can use the “Focus Areas” feature in AcqKnowledge Software to simplify their data review.
Studying Flow Mediated Responses in Isolated VasculatureInsideScientific
During this webinar Dr. Éric Thorin, a leading expert in the effects of shear stress in the vasculature, explains key concepts in setting up a system for the purpose of examining flow-mediated responses in isolated blood vessels. The webinar sponsor, Living Systems Instrumentation, has been supplying tools for in vitro studies of cardiovascular function for over 20 years. Viewers will gain an understanding of how to setup and utilize a pressure arteriograph capable of simultaneous control of intravascular pressure and intraluminal flow.
Background information: The physiological significance and effects of flow on controlling and coordinating vascular function are well-appreciated. However, flow-mediated regulation of vascular function is a complex and difficult mechanism to study experimentally. Care must be taken to select appropriate instrumentation to allow for precise control of intravascular pressure and intraluminal flow, while minimizing artifacts introduced by the small size of glass cannulae. With proper simultaneous control of intravascular pressure and intraluminal flow, the researcher will be able to explore such responses as flow-mediated dilation, flow-induced constriction and other physiological responses that depend upon shear stress in the vasculature.
About Our Presenter:
Dr. Éric Thorin has a long-standing interest in the study and mechanisms of ageing related to the vascular endothelium. His laboratory has developed several approaches to investigate the functional consequences of ageing combined with risk factors for cardiovascular diseases (CVD) on the evolution of a reversible endothelial dysfunction to an irreversible vascular disease. His main areas of research include the study of the cerebrovascular and peripheral vascular dysfunction in the mouse model of human dyslipidemia and atherosclerosis, the molecular mechanisms leading to endothelial cell senescence and the impact of risk factors for CVD in patients with obesity, diabetes and coronary artery disease.
Driving Slow-Oscillations (1 Hz) in rats with optical readout via two-photon microscopy.
Alternative download link: https://dl.dropboxusercontent.com/u/6757026/slideShare/neuromodFUS_v2016.pdf
POWER SPECTRAL ANALYSIS OF EEG AS A POTENTIAL MARKER IN THE DIAGNOSIS OF SPAS...ijbesjournal
The detection and diagnosis of various neurological disorders are performed using different medical
devices among which electroencephalogram (EEG) is one of the most cost effective technique. Though
significant progress had been made in the analysis of EEG for diagnosis of different neurological
disorders, yet detection of cerebral palsy (CP) is not quite clear. This study was performed to analyze the
EEG power spectrum density (PSD) of spastic CP and normal children to find if any significant EEG
patterns could be used for early detection of CP. Twenty children participated in this study out of which ten
were spastic CP and other ten were normal healthy children. EEG of all the participants was recorded
from C3 C4 and F3 F4 regions following montage 10-20 system. The artifact-free EEG signals of 15
minutes duration was extracted for spectral analysis using Fast Fourier Transformation (FFT) algorithm
in MATLAB and power density spectrum (PSD) was plotted. The PSD revealed high intensity power peak
at frequency of 50Hz and smaller at 100 Hz, which was consistent for all healthy subjects. In case of
spastic CP children, high intensity peak at 100Hz were prominent and smaller peak was observed at 50Hz.
The high intensity 100Hz peak observed in the PSD of spastic CP patients demonstrated that this tool can
be used for early detection of spastic CP.
Computational methods have complemented experimental and clinical neurosciences and led to improvements in our understanding of the nervous systems in health and disease. In parallel, neuromodulation in form of electrical and magnetic stimulation is gaining increasing acceptance in chronic and intractable diseases. First, we will present models of slow dynamics emerging on large cortical scales controlled by both subcortical networks and neurovascular coupling. The focus is on modeling migraine, though this approach is nested within the wider interest in modeling slow and large-scale dynamics in the brain. The aim is not only to better understand pain conditions and fluctuations in the resting state that causes these conditions but also to identify new opportunities to intervene with medical devices and implantable neuroprostheses. To this end, we then present the relevant state of the art of neuromodulation in migraine and approaches in fusion of both developments towards a translational computational neuroscience.
Rapid fragmentation of neuronal networks at the onset of propofol-induced unc...home
The neurophysiological mechanisms by which anesthetic drugs cause loss of consciousness are poorly understood. Anesthetic actions at the molecular, cellular, and systems levels have been studied in detail at steady states of deep general anesthesia. However, little is known about how anesthetics alter neural activity during the transition into unconsciousness. We recorded simultaneous multiscale neural activity from human cortex, including ensembles of single neurons, local field potentials, and intracranial electrocorticograms, during induction of general anesthesia. We analyzed local and global neuronal network changes that occurred simultaneously with loss of consciousness. We show that propofol-induced unconsciousness occurs within seconds of the abrupt onset of a slow (<1><4 mm) neuronal populations maintain the millisecond-scale connectivity patterns observed in the awake state, and spike rates fluctuate and can reach baseline levels. However, neuronal spiking occurs only within a limited slow oscillation-phase window and is silent otherwise,
fragmenting the time course of neural activity. Unexpectedly, we found that these slow oscillations occur asynchronously across cortex, disrupting functional connectivity between cortical areas. We conclude that the onset of slow oscillations is a neural correlate of propofol-induced loss of consciousness, marking a shift
to cortical dynamics in which local neuronal networks remain intact but become functionally isolated in time and space.
Marom Bikson speaks at the BrainSTIM2015 - Targeting transcranial Electrical Stimulation (tES) using EEG. Includes how to use EEG to inform transcranial Direct Current Stimulation (tDCS) montages. And critical pitfalls in concurrent recording. Stay tuned for our upcoming paper on reciprocity.
The complete video can be found here: https://www.youtube.com/watch?v=yYmDQB7qSCE
The first publication on the topic can be found here http://neuralengr.com/wp-content/uploads/2016/05/2016-Cancelli-A-simple-method.pdf
Related technology can be found here http://soterixmedical.com/research/monitoring/eeg
Magnets - Not Drugs: TMS IMMH San Antonio 2014Louis Cady, MD
In this talk, Dr. Cady covers a remarkable new treatment for depression: transcranial magnetic stimulation. The historical roots of this treatment are traced, followed by a review of the literature in terms of the proven efficacy of this treatment. A comparison with ECT shows that TMS has a very favorable profile, with remarkably fewer side effects and incredibly better tolerated side effects compared to ECT. Given that this was a "CME" talk, off-label uses of TMS were reviewed, including stepping stones for future avenues to explore
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Couples presenting to the infertility clinic- Do they really have infertility...
Electrophysiology in vivo
1. Electrophysiology (Ephys)
A key feature when studying neuro-vascular and
Claus Mathiesen
Department of Neuroscience and Pharmacology
metabolic coupling
Aim:
Teach you the basics of in vivo electrophysiology
!
Claus Mathiesen, M.Sc. Ph.D.
2. Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Outline of my talk
Core of electrophysiology
!
EEG
!
Field potentials
!
Contributions from different cell types
!
Spike (action potential) activity
!
Pro and Cons with types of ephys recording
3. Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 3
The core of Ephys
Ephys signal is measured in voltage (V), current (I),
and resistance (R) or conductance (G=1/R)
!
These variables are related according to Ohm’s law:
V = I ◦ R or I = V ◦ G
!
Ephys signal has different frequencies
!
Frequency is measured as oscillation per second (Hz)
!
Each type of neuronal activity is located within areas
in the frequency band running from 0 to 5000 Hz
4. The generator of the Ephys signal
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology (Dias 4)
Neurons are like a battery
Negative inside (-60 to -70 mV)
Generate action potentials via
voltage-gated ion-channels
Some have pacemaker activity
5. Excitatory-PostSynaptic-Potential (EPSP)
Presynaptic release of
transmitter
Transmitter-gated ion-channels
Ion-flux
Potential changes
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology (Dias 5)
EPSP
fEPSP
6. Commonly recorded Ephys signal in the in vivo
Claus Mathiesen October 2012
EPSP
fEPSP
brain?
Intracellular potential changes as
Synaptic events
Spike activity
Graded potentials
Extracellular potential changes as
Evoked field excitatory-postsynaptic
potentials (fEPSPs)
Single unit (cell) activity (SUA) of
spikes/action potentials
Multi-unit activity (MUA) of spikes
Non-spiking, graded potentials (EEG)
SUA
MUA
EEG
7. From low frequencies to higher frequencies
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology (Dias 7)
8. Department of Neuroscience and Pharmacology (Dias 8)
EEG (ElectroEncephaloGraphy)
Claus Mathiesen October 2012
Richard Caton 1875: The electric
currents of the brain. BMJ 2.
278.
!
Hans Berger 1929: Über das
elektreenkephalogram des
menschen. Arch. Psychhiatr.
Nervenkr. 87, 527-570
In the beginning EEG was used as indicator for
sleep stages (Slow wave, light, REM)
together with recording of muscular tone
(EMG)
diseases like epilepsy and brain damage
10. Brain activity and EEG
Possibly only a small proportion of nerve cells
generate synchronous spikes in normal mental state
!
Cerebral rhythms picked up by EEG represent
synchronous synaptic activity
!
EEG measures only a small fraction of the total brain
activity due to
Dilution (distance-2 ≈ amplitude)
Variability in conductivity
Mixed orientation of active dendrites
Lack of synchronous activity
Claus Mathiesen October 2012
11. Irregular activity leads to high frequency and low amplitude
Claus Mathiesen October 2012
EEG
Synchronized activity leads to low frequency and high
amplitude EEG
13. Delta rhythms (<4 Hz EEG)
Marker for slow-wave sleep also called deep sleep.
In slow-wave sleep the brain recovers
Claus Mathiesen October 2012
14. Theta rhythms (4-7 Hz EEG)
In rodents the theta rhythms (4-10 Hz) originate
from hippocampus and is an indicator for
paradoxical sleep (rodents REM sleep)
Exploration and sniffing
!
In humans the theta rhythms originate from cortex
and is an indicator for
Drowsiness
Meditation
Light sleep states
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 16
15. Alpha- (8-13 Hz) and Beta-rhythms (14-30 Hz)
Quiet awake Open eyes
closed eyes
Alpha Beta
Claus Mathiesen October 2012
16. Gamma rhythms (30-80 Hz EEG)
Represent spike timing of a large ensemble of neurons
Dependent on GABA interneurons that synchronise the
spiking of pyramidal cells
!
Synchronous neuronal activity is a tool for dealing with
information with different modalities:
Perceptual binding
Attention
Working memory
!
Can be observed at multiple spatial scales, from single-unit
recordings to MEG and scalp EEG
Claus Mathiesen October 2012
Gamma
17. Claus Mathiesen October 2012
Gamma activity
(Adapted from Sumiyoshi et al., 2012, Neuroimage)
18. Bands for different Ephys signals
Gamma 30-80 Hz (memory)
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Delta <4 Hz (deep sleep)
Theta 4-7 Hz (REM sleep, drowsy, meditation)
Alpha 8-13 Hz (eyes closed awake)
Beta 14-30 Hz (active awake, open eyes)
Evoked field potential
0.1-1000 Hz
19. What generates the evoked field potential?
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Synchronic activation:
•Transmembrane current flow
•Extracellular current flow and the
resistant properties of the extracellular
media àvoltage changes in the field
potential
0.5 mV
20. Shape of evoked field potentials as function of
anatomy and location
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 23
Hippocampus or
Cerebral
21. Interpretation of an evoked field potentials
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 24
Degree of excitation
=
Number of open
AMPA receptor
channels
Ca2+ dependent
K+ current
+NMDA rec.
antagonist
22. From field potentials to Current Source Density
í
í
í
í
í
í
í
í
í
í
Depth [μm]
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 26
Time [s]
í
í
í
Jessen
et
al
2014
Mathiesen
et
al.
2011
Sink
Iso
Source
LFP
Depth profile
Time [s]
1st
2nd
Current source density
CSD Map
23. Current Source Density (CSD)
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 25
Neuronal activity à Transmembrane
current generating ensemble of current
sources and sinks à Extracellular current
flow à Potential differences (Field
potentials) due Resistance in the
extracellular media
The first spatial derivative of the Field
potential is equal to Current Flow
Density.
The Current Flow Density is a vector
indicating the amplitude and direction of
current flowing through a giving point in
the extracellular medium.
The second spatial derivatives of the
field potential is equal to the Current
Source Density (CSD).
The Current Source Density correspond to
the transmembrane current
Field potential
Current flow density
Current Source Density
Nicholson, Freemann 1975
Source
Sink
Spatial
derivative Spatial
derivative
24. Contribution to Ephys from different cell type
Cerebellar
pyramidal
Contribution to the field potential
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Neurons Glia
Cortical
pyramidal
Interneurons Astrocyte Oligodendrocyte Microglial
Stellate cell
Principal output Relay
K+ buffer
Blood flow
House keeper
Calcium waves
Myelinate Phagocyte
Major Major Middle
Minor (EEG)
(Minor) (Minor) (Minor)
25. Bands for different Ephys signals
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Evoked field potential (synaptic strenghts)
0.1-1000 Hz
Spikes /action potentials
300-3000 Hz peak 1000 Hz
• Single unit activity
(1-100 spikes/s)
•Multi unit activity
Delta 4 Hz (deep sleep)
Theta 4-7 Hz (REM sleep, drowsy, meditation)
Alpha 8-13 Hz (eyes closed awake)
Beta 14-30 Hz (active awake, open eyes)
Gamma 30-80 Hz (memory)
Adrian
Moruzzi
1939:
Impulses
in
the
pyramidal
tract.
J.
Physiol.
97,
153-‐199
26. Spiking in respons to synaptic input
Cascades:
Transmitter release
Transmitter-gated channels (spatial and temporal summation)
Voltage-gated channels
Calcium spikes
Sodium spikes
Potassium re-polarize cell
Calcium mediated potassium current
!
Or sodium spikes as a consequence of pacemaker activity
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology Dias 32
27. Single unit spike activity (Purkinje Cell)
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
5 ms 5 ms
0 1000 2000 3000 4000 5000
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0.000
Power
Frequency
Simple spike Complex spike
Kirsten Thomsen
28. Example of single unit activity (SUA)
Spike- waveform Regular
InterSpikeInterval
Event autocorrelation
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Herrik et al. 2010
Irregular
Burst
Regular Irregular Burst
29. Department of Neuroscience and Pharmacology (Dias 35)
Methods in Multi-unit activity (MUA)
Single electrode
!
!
!
Stereotrode
!
!
!
Tetrode
Claus Mathiesen October 2012
Low resolution
•distance
Root-Mean-Square (RMS)
!
Better resolution
•distance + location
!
!
Even better resolution
•Distance + 2D location
30. Pro and Cons with types of ephys recording
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Method Pro Cons
EEG Non-invasive,
comparative to human
studies, timing
Bad localisation
(3-5cm), no info on
cell types, or mode of
Evoked field potentials Robust indicator of action
synchronous synaptic
activity
Invasive, only on
evoked response, not
well with non-aligned
Current source cells
density
Robust indicator of
transmembrane ion
flux, better
localisation
same as above
Single unit activity
(SUA)
Info from one cell Only one cell
Multi unit activity
(MUA)
Better overall
estimation of spike
activity
lack cell type
information
31. Bands for different Ephys signals
Gamma 30-80 Hz (memory)
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology
Delta 4 Hz (deep sleep)
Theta 4-7 Hz (REM sleep)
Alpha 8-13 Hz (light sleep, or quit awake)
Beta 14-30 Hz (active awake)
Evoked field potential (Synaptic strengths)
0.1-1000 Hz
Spikes /action potentials
300-3000 Hz peak 1000 Hz
• Single unit activity
(1-100 spikes/s)
•Multi unit activity
32. THANK YOU FOR YOUR ATTENTION
Claus Mathiesen October 2012
Department of Neuroscience and Pharmacology (Dias 38)