Gerry S. Oxford, Ph.D.Paul & Carole Stark Neurosciences Research Institute

Indiana University School of Medicine

Indianapolis, Indiana

Gerry S. Oxford, Ph.D.Paul & Carole Stark Neurosciences Research Institute

Indiana University School of Medicine

Indianapolis, Indiana

The Future of Neuroscience:New Opportunities for Research

New Opportunities for Society

The Future of Neuroscience:New Opportunities for Research

New Opportunities for Society

Why Study the Brain?Why Study the Brain?

• Over 40% of the human genome is related to the brainOver 40% of the human genome is related to the brain

• 70-80% of the ATP synthesized serves to maintain cell 70-80% of the ATP synthesized serves to maintain cell membrane potentials that are the foundation of excitabilitymembrane potentials that are the foundation of excitability

• It is the one organ that fundamentally defines what is It is the one organ that fundamentally defines what is “human” in all of us ... the need to understand “self”.“human” in all of us ... the need to understand “self”.

Scientific / Cultural Perspective

Why Study the Brain?Why Study the Brain?

• 50 million Americans have a permanent neurological disability.50 million Americans have a permanent neurological disability.

• 4 million older Americans suffer from Alzheimer’s Disease at a 4 million older Americans suffer from Alzheimer’s Disease at a cost of $100 billion/year.cost of $100 billion/year.

• 2 million Americans suffer from schizophrenia2 million Americans suffer from schizophrenia

• 500,000 Americans suffer from Parkinson’s Disease500,000 Americans suffer from Parkinson’s Disease

• Substance abuse, obesity, eating disorders, etc.Substance abuse, obesity, eating disorders, etc.

Clinical / Societal Perspective

A Brief History of Neuroscience

• “Brain Science” has been around for centuries, but has largely been observational and phenomenological, rarely mechanistic.

• Contributions to progress from various classical, but largely independent research disciplines

• Emergence of neuroscience as a separate field inherently and fundamentally multidisciplinary.

– (1965) Harvard Neurobiology Department – Stephen Kuffler– (1966) UNC Neurobiology Curriculum– (1970) Society for Neuroscience formed – now 34,000 members (sfn.org)

• 95% of all existing literature with the term “brain”, “neuron”, or 95% of all existing literature with the term “brain”, “neuron”, or “neurotransmitter” published since 1985.“neurotransmitter” published since 1985.

• 1990s: The Decade of the Brain - presidential proclamation

• How far have we come? Where are we going?

1990s - Decade of the Brain1990s - Decade of the Brain

• A concept developed by neuroscientists and implemented by a A concept developed by neuroscientists and implemented by a presidential proclamation by George Bush on July 25, 1989 presidential proclamation by George Bush on July 25, 1989 citing...citing...

– The need for public awareness and support of brain science The need for public awareness and support of brain science

– The dawn of a new era of discovery in brain researchThe dawn of a new era of discovery in brain research

– The justifiable hope of individuals stricken with neurological and The justifiable hope of individuals stricken with neurological and mental disordersmental disorders

• How far have we come? Where are we going?How far have we come? Where are we going?

Nobel Laureates with “Neuroscience” Focus

• 1991 – Erwin Neher & Bert Sakmann (Patch Clamp Recording)

• 1994 – Al Gilman & Martin Rodbell (G-protein signaling)

• 1997 – Stanley Prusiner (Discovery of prions)

• 2000 – Arvid Carlsson, Paul Greengard, & Eric Kandel (signal transduction in the nervous system)

• 2003 – Paul Lauterbur & Peter Mansfield (MRI Technology)

• 2003 – Peter Agre & Rod MacKinnon (Ion Channel Structure)

• 2004 – Richard Axel & Linda Buck (Olfactory Receptors)

Technological Advances Fueling the Rebirth Technological Advances Fueling the Rebirth of Neuroscienceof Neuroscience

• The rapid pace of neuroscience research and advancement of The rapid pace of neuroscience research and advancement of knowledge reflects both a manpower surge and ...knowledge reflects both a manpower surge and ...

• New and improved technologiesNew and improved technologies

– Molecular biologyMolecular biology

– Molecular geneticsMolecular genetics

– In vivo In vivo imaging methods (PET, fMRI, MR spectroscopy, DTI)imaging methods (PET, fMRI, MR spectroscopy, DTI)

– Cellular imaging (confocal microscopy, indicator dyes)Cellular imaging (confocal microscopy, indicator dyes)

– Cellular recording (brain slice & patch clamp techniques)Cellular recording (brain slice & patch clamp techniques)

– Cellular stimulation (channel-rhodopsins and caged glutamate)Cellular stimulation (channel-rhodopsins and caged glutamate)

– Computational and neuroengineeringComputational and neuroengineering

Modern neuroscience methods allow study of nervous system activity at the level of ...

from Gao et al. (1996) Science 272:545-547.

The whole brain

from Stuart & Sakmann (1994) Nature 367:69-72

Single nerve cells

0

10

pA

c

o

30 msec

ionchannels

glasspipette

Singlemolecules

Functional Brain Mapping: Pre-Decade of Functional Brain Mapping: Pre-Decade of BrainBrain

• John Hughlings Jackson observed that muscle John Hughlings Jackson observed that muscle contractions during epileptic seizures often contractions during epileptic seizures often migrated to adjacent regions of the bodymigrated to adjacent regions of the body

John Hughlings Jackson

• Wilder Penfield analyzed the pattern of body Wilder Penfield analyzed the pattern of body movements during cerebral stimulation in surgical movements during cerebral stimulation in surgical patientspatients

• Paul Broca defined the concept of cortical Paul Broca defined the concept of cortical localization of function and mapped the anatomical localization of function and mapped the anatomical regions of the human cerebral cortexregions of the human cerebral cortex

“Whoa! That was a good one! Try it, Hobbs --Just poke his brain right where my finger is.”

Penfield’s Legacy ?

Functional Brain Mapping: Post-Decade of Brain

Modern Brain Research:Modern Brain Research:A Process of Discovery and Re-examinationA Process of Discovery and Re-examination

• New horizons of knowledgeNew horizons of knowledge

– Gene families of important neuronal moleculesGene families of important neuronal molecules– Common biochemical signals for substance abusing behaviorsCommon biochemical signals for substance abusing behaviors– Signals underlying the creation and storage of memoriesSignals underlying the creation and storage of memories– Distributed organization of cognitive functionDistributed organization of cognitive function

• Teaching old dogmas new tricksTeaching old dogmas new tricks

– Glial cells play larger roles than support and nutritionGlial cells play larger roles than support and nutrition– Dendrites are not passive observers in synaptic signalingDendrites are not passive observers in synaptic signaling– Adult nerve cells, given proper care, can repair and recoverAdult nerve cells, given proper care, can repair and recover– Neurotransmitter receptors are more elusive targets than Neurotransmitter receptors are more elusive targets than

previously suspectedpreviously suspected

Decade of the Brain: Where are We Now?

• Human Genome Project - but other genomes may be as important (rat, mice, Fugu, C. elegans)

• New technologies (genomics/proteomics, cellular and non-invasive whole brain imaging, neural networks/robotics, single channel electrophysiology)

• Answers are not as simple as originally thought (complex multigenetic disorders – schizophrenia, Parkinson’s) or the absence of understanding of how or what gene products do (Huntingtin).

• To progress, genetic information must be translated into animal and non-animal models of disease for developing safe, rational therapies. This is hard!

• “Translational research” is key. Often defined as unidirectional “bench-to-bedside”, but information flow in the other direction is just as important.

Decade of the Brain: Some Greatest Hits?

or “So that’s how it works!!”

• Ion Channel Research: Advanced electrophysiological recording meets X-ray crystallography

• Pain: A Holy Grail Discovered

• Synaptic Plasticity: Common signaling turned on its Hebb

• Glial Cells: Not just silent partners.

• Sleep: A chance to learn?

• Neurotransmitter Receptors: Partnerships in signaling

“Cell-Attached”

Whole Cell

Inside-Out

Outside-Out

Patch Clamp Recording Configurations

GlassPatch Pipette

ToAmplifier

Cell

Ion Channels

0

10

pA

c

o_ _ _ _

30 msec

GentleSuction

-60 mV

0 mv

Trial #1

Trial #2

Trial #3

Trial #4

Trial #5

Trial #n

...

Averaged Single Na Channel Currents

time = 0

Voltage

Crystal Structure of a Potassium Channel (1998)

How Do Voltage-Gated Channels “Gate”?

1 nA

10 pA

-100 mV

+60 mV

Membrane Voltage (clamped)

SlidingS4 HelixModel

ClosedOpen

S4 PaddleModel

S4 Paddle ModelClosed

Crystal Structure

S4 Paddle ModelOpen

Crystal Structure

Open Closed

Natural Products and the Pain Pathway

The TRP Channel Superfamily

• TRPV1 cloned by David Julius (UCSF) in 1997.

• 28+ mammalian homologues are tetrameric ion channels (6TM domain subunits), with several other conserved domains.

• Many of the TRPs have high calcium permeability (PCa/PNa > 8).

• A common feature appears to be involvement in physical sensory transduction (thermal, mechanical, osmotic, calcium depletion).

• TRPV1 null mice do not have inflammatory pain.

Moiseenkova-Bell et al. PNAS 105:7451, 2008

TRPV1 Kv1.2

PAINPAIN

Capsaicin

TRPV1

Heat

Acid

DRG ElectricalResponse

Ion Flux

thus TRPV1 is a “multi-modal” transducer of various painful stimuli.

TRPV1 and Pain SensationTRPV1 and Pain Sensation

0 20 40 60 80 100 120

(Pepper / 10 M CAP) x 100

Habenero

Capsaicin

Thai Green

Wax

Poblano verde

Pepper Pungency and TRPV1 Activation Are Correlated

(Data replotted from Caterina et al. Nature 389:817, 1997)

Scoville Scale

Consider a hippocampal CA1 pyramidal neuron with two inputs

AB

EPSP from indicated single input AP

5mV

A

B

Consider a hippocampal CA1 pyramidal neuron with two inputs

AB

5mV

EPSP from indicated single input AP

4 min

Consider a hippocampal CA1 pyramidal neuron with two inputs

AB

5mV

EPSP from indicated single input AP

4 min

Consider a hippocampal CA1 pyramidal neuron with two inputs

AB

5mV

EPSP from indicated single input AP

10 min

Long Term Potentiation (LTP):

An increase in synaptic strength associated with activity

AB

0

10

mV

HF stimA

HF stimB

HF stimA+B

0 30 min

Amplitude of EPSPs evokedby single AP from input A

applied each minute

Magee & Johnston (1997) Science 275:209. Markram et al. (1997) Science 275:213.

Action Potentials Moving in “Reverse”Are the Coincidence Factor

Zaminillo et al. (1999) Science 284:1805 Shi et al. (1999) Science 284:1811

AMPA Receptor Redistribution is Involved in LTP

Wilson & McNaughton (1994) Science 265:676-679

Multi-neuronRecording

Box

48X

Sleep and Memory Consolidation: Hippocampal “Place” Neurons

Pennartz, Lee, Verheul, Lipa, Barnes, and McNaughton (2004) J. Neuroscience 24:6446-6456.

VentralStriatum

Ventral Striatum “Recapitulates” Experience During Sleep

T-Maze

K+/Na+/Ca+

GPCRGPCR

GPCRGPCR

Oligomerization:Hetero- or Homo- ?

All GPCR’s ?Functional significance ?

? ?Gα and Gβγ:

Stoichiometry ?Reserves ?

RGS

?

Multi-domain regulator of G-proteins:

Role of different domains ?

Are the signaling pathway components compartmentalized?

What don’t we know about GPCR’s?

Kenakin TIPS 25: 186-192, 2004

GPCRs: A Study in Functional Complexity

D2R(GoLoco, siRNA)

D2R(GoLoco, siRNA)

D2R(NPA, DHX)

D2R(NPA, DHX)

D2R(Spinophilin)

D2R(Spinophilin)

D2R(Functional?)

D2R(Functional?)

From Molecules to Minds: Challenges for the 21st Century

A National Academy of Sciences Workshop

July 2008

• Grand Challenge 1: How does the human brain work and produce mental activity?

• Grand Challenge 2: Nature versus Nurture: How does the interplay of biology and experience shape our brains and make us who we are?

• Grand Challenge 3: How do we keep our brains healthy? How do we protect, restore, or enhance the functioning of our brains as we age?

From Molecules to Minds: Challenges for the 21st Century: Workshop Summaryhttp://www.nap.edu/catalog/12220.html

From Molecules to Minds: Challenges for the 21st Century

A National Academy of Sciences Workshop

• Grand Challenge 1: How does the human brain work and produce mental activity?

• Mapping the brain

• Technical Advance - the “Brainbow”, color coding neuronal types

• Technical Advance - the neuronal “light switch”, activating neurons with light

• Technical Challenge - spatial and temporal resolution (fMRI, PET, arrays)

• Neural networks

• Scaling: too big or too small?

• Resolution: fine cellular detail or the basics of signaling?

• Bias: intuition from psychology or a more agnostic approach to learning?

From Molecules to Minds: Challenges for the 21st Century

A National Academy of Sciences Workshop

• Grand Challenge 2: Nature versus Nurture: How does the interplay of biology and experience shape our brains and make us who we are?

• Brain Plasticity

• Adult neurogenesis - you do have more brain than you’re born with!

• Mental calisthenics - synaptic structures indicate “use it or lose it”

• Interaction between genes and environment

• While gene X may determine a behavior, expression of gene X can be regulated by experience.

• Tremendous clinical implications for schizophrenia, Alzheimer’s, bipolar disorder, etc.

From Molecules to Minds: Challenges for the 21st Century

A National Academy of Sciences Workshop

• Grand Challenge 3: How do we keep our brains healthy? How do we protect, restore, or enhance the functioning of our brains as we age?

• Why does the brain age? - inflammatory markers, decreased transcription, cumulative environmental toxins.

• How are genes involved? - complicated and multifactorial

• Imperfect therapies - most drugs have side effects reflecting the complicated roles of drug target receptors.

• Ethical considerations - behavioral therapies, stem cells, engineering transplantation, advanced robotics.

The Next Decade of the Brain:

What Now?

• siRNA/shRNA: New tools for understanding function

• Adult stem cell biology: Promise for regenerative therapies

• Application of genomics as a high throughput tool

• Neurobotics: If you can think it, the robot can do it.

GIRK4 (adult) Pax6 (E15.5)

GENSAT: Transgenic BAC Cloning of Molecular Distributionswww.gensat.org

D1 Dopamine Receptor (adult)

Gene of Interest

EGFP

BAC

“Monkey See, Robot Do”: A Brain Operated Prosthetic Arm

Thank Thank You for You for

Your Your Attention Attention

!!

“Dr. Oxford, May I be excused? My brain is full.”“Dr. Oxford, May I be excused? My brain is full.”