Travels of a Functional Neuroanatomist �through Pain, Audition, Environmental Enrichment, Sexual Dimorphism…�Interconnections and Dead Ends

J. Timothy Cannon, PhD

Or…

25 Years in the Wilderness

Or…

A Career Based on Untreated ADHD�with a Pinch of Tourette’s �having “recovered” from Guillain-Barré

Or…

Or…

Or…

Paths Taken, at Least Momentarily

• Audition
• Ear Wiggling
• Ear Rumbling
• The Acoustic Startle Pathway
• The Pinna Reflex Pathway
• Pinna Startle
• Early Auditory Relay Nuclei Projections to the Inferior Colliculus�
• Pain
• Pain-Induced Vocalizations
• Analgesia
• Anal-gesia
• Rotation-Induced Analgesia
• Electroconvulsive Shock-Induced Analgesia
• MSG-induced Destruction of the Arcuate Nucleus
• Raphe Magnus Lesions Disrupt Brain- and Stress-Induced Analgesia
• Body Region Shocked Does Not Define the Pharmacological Basis of Stress-Induced Analgesia
• Injury-induced sensitization to pain�
• How to Masturbate a Rat (You can’t, and they don’t vomit either.)�
• Enrichment
• Antidepressant – antioxidant
• Anxiety
• Pain
• Fear
• Memory
• Spatial
• Fear
• Anxiety
• Foraging

​

• Electromagnetic Field Effects on Sperm Motility�
• Autism - Prenatal Androgen Levels Reflected by Finger Ratios and
• SAT Performance
• Ball Toss Accuracy
• Adult Traits Related to Autism
• General Personality Traits (Big Five)
• Sexual Personality Traits

​

• Spinal Projections of Early Auditory Relay Nuclei�
• Cognitive Deficits Associated with Soccer (there are many)�
• Post-Decapitation Seizures�
• Epilepsy�
• Sensory Responses of Neurons in the Lateral Cervical Nucleus�
• Long Ascending Projections of the Substantia Gelatinosa and Subjacent Dorsal Horn in the Spinal Cord of the Rat�
• Opioid and Non-Opioid Forms of Brain Stimulation-Induced Analgesia�
• Opioid and Non-Opioid Forms of Stress-Induced Analgesia�
• Fear
• Neuroanatomy of fear-induced freezing
• When should you do extinction (get right back on the horse?)�
• Itch�
• Saccharine consumption (sweet preference) pain�
• Sex Difference in Noise Annoyance & Loudness�
• Factors in Choosing a Mate�
• Circannual Stress in Snails�
• Sexy 7 (Maybe 8)�
• Love Darts�
• Zah: The Ultimate Profane Statement (4 Letters and Gender-Specific)�
• Moon Illusion�
• Faith Healing�
• Animal Research�
• Birth Month and Belief in the Paranormal: Related to schizophrenia?�
• Who Keeps Diaries and Why�
• Sexual Dimorphism�

In the beginning…

I looked like this:

I’m on the left…

Sadly, sometimes like this…

The pants and vest were gifts…

Thanks to making this PowerPoint, I finally came to understand why the “older” students in Jack Dunstone’s lab called him …

“The Big D”

It was a Rosebud moment!

Dualism

Where human behavior came from…

Where human behavior comes from…

Got Complexity??

• 100-200 billion neurons
• 1-2 trillion glial cells
• ~5,000 synapses per neuron
• Each synapse can achieve “numerous” levels of activity
• It’s been estimated that there are more potential synaptic states in the human brain than atoms in the known universe
• You do the math
• There, I said it… “math”

A Neuroanatomist’s Act of Faith:

If they LOOK different, they ACT different.

And they sure look different!

Hello, my pretties!!!

They even hold “hands” ☺

Neuron “Man”

The Simple Story

Retrograde Transport:�My Long-Term Favorite

Anterograde

Retrograde

Gross Anatomy

Ventricles – I LOVE Ventricles!

They aren’t simply sewers for waste or sources for cushioning fluid…

Receptor and Neurotransmitter/Drug Interactions

The Auditory System:�The Only Game in Town at the University of Maine

Rats selectively bred to escape from (or not escape from) intense white noise.

While in charge of my advisor’s precious breeding colony, the animals decided to stop producing pups almost to the point of their extinction. At this point, I swore, “With God as my witness, I will never breed animals again!”

One of many oaths I have not kept…

The Peripheral Auditory System

Can you wiggle and/or rumble?

How about click?

Sensory Organs Aren’t Passive�(The Beginning of a Recurring Theme)

• Outer hair cells act as little muscles.
• Objective tinnitus
• Otoacoustic emissions
• There are sex differences

Auditory System Pathways

My Version of the �Early Auditory System

I Cut Decussating Fibers

And Gently Restrained Rats Like This…

“Why?” you ask...

Increasing Sound Intensities Trigger Different Auditory Behaviors�(Another Recurring Theme)

• Pinna (Preyer) Reflex - Wiggle
• Middle Ear Muscles – Rumble
• Acoustic Startle
• Escape

Findings

• Large decussating fibers carry acoustic startle and escape

​

• Pinna reflex doesn’t decussate

​

• Don’t know about middle ear muscles, but I’m betting similar to pinna

These purple bad boys (acoustic nerve neurons) are now thought to run the acoustic startle reflex. There are only about 50 associated with each rat auditory nerve… and not “everyone” has them.

But I Was REALLY Interested in Enrichment

But Researchers Began Doing Stuff Like This:

I was NOT amused.

and sewing kitten eyes shut…

Then, I Discovered Pain

Actually… Pain Inhibition

Actually…

Pain Inhibition �Produced by Brain Stimulation

Or, appropriately named,

Stimulation-Produced Analgesia

SPA

The meaning has shifted in common pain parlance.

But that’s not important right now…

Not trying to inhibit “pain”…�but rather chronic (useless) pain

A Digression�I was very excited to find a former biology faculty member studied SPA

His SPA, however, meant Sperm Penetration Assay

This reminds me of the year my lab spent trying to masturbate rats because I was sure that electric blankets affected sperm motility.

But that’s not important right now…

Arrived at UCLA to study pain…

UCLA had great procedures for doing retrograde tracing with HRP (Horseradish Peroxidase – actually, peroxidase from horseradish – ask a chemist). �

So I wanted to test then current dogma that all axons coming out of the cochlear n. ended in nuclear groups before the Inferior Colliculus…

No wait!!!

​

A Digression…

On the way to UCLA, I lost almost ALL of my dissertation data.

WHAT?! ANOTHER?!

Don’t use masking tape to seal boxes destined to be shipped from Maine to California by the US Post Office… or any other shipping medium!

​

Horseradish Peroxidase (HRP) �into the Inferior Colliculus

Retrograde

This lit up lots and lots of neurons in the cochlear nucleus

Now back to pain...

Actually back to…��Stimulation-Produced Analgesia

You can’t understand how SPA works without knowing… that is, dimly understanding… how pain is organized within the nervous system.

A Constellation of Behaviors Organized at Multiple-Levels �of the Nervous System

Say it over and over and over and over and over…

PAIN:

Increasing Shock Intensities Trigger Different Pain Behaviors�(Return to a Theme)

• Flinch/Jump
• Run
• Vocalize During
• Vocalize After
• Attack

• Spinal Cord
• Lower Brain Stem
• Midbrain – PAG (Tourette’s?)
• Thalamus - Limbic
• Limbic-Frontal Cortex

The Neural Complexity Begins in the Skin at the Receptor Ends

Substance P is made in the cell body.

But also…

Shipped to the spinal cord and used to communicate with other neurons.

Shipped to the skin to be used for what??

General Divisions of the Gray Matter of the Spinal Cord:�Rexed’s Laminar Scheme

Remember the act of faith: If it looks different, it acts different…

It’s complicated in there!

Ascending Pain Pathways in the Spinal Cord Are Complicated Too

As are Ascending Pain Pathways in the Brain

Note the Periaqueductal Gray (PAG)

Things We’ve Blown Up to Treat Chronic Pain

Too many to mention and the bad news is that most of them don’t work.

Melzack and Wall: �Gate-Control Theory of Pain

Made it acceptable to talk about active pain modulation…

What About Pain-Inhibition?

• Historically, and to this day, opiates are probably the most reliable analgesics available for moderate to sever pain and suffering. �
• How do opiates work? �
• Up through the latter parts of the last century (remember that century?). We didn’t have a clue until…

Opioid-Mania!!!

• With the discovery of opiate receptors, the pieces began to fall into place.

​

• Receptors were in many brain and spinal cord locations that were already thought to be involved in pain transmission – so they were in the right locations to play roles in pain inhibition.

Opioid Receptors

Note the Periaqueductal Gray (PAG) – loaded!!!

Is it Opioid?�Three standard tests used to determine if something is opioid-mediated:

• Blocked by naloxone (or another antagonist)�
• Shows tolerance (reduced effect) with repeated administration�
• Shows cross-tolerance with other opioids/opiates

Remember SPA?�(Stimulation-Produced Analgesia)

• SPA played an important role in the discovery of endogenous opioids (the brain’s own morphine). �
• Most folks suspected that opiate receptors had not evolved in the “hopes” of us running into poppy seeds.

Enter John C. Liebeskind...

​

The Don…

Taken during my candle period.

B.F. Skinner

Awarded John his only C in college. John kept this picture on his bulletin board for his entire career.

​

B.F. lived at 2100 N. Washington Ave. for a time…

​

But that’s not important right now...

Dave Mayer

• Dave et al., following up on an earlier report, showed that SPA (remember SPA?) from the Periaqueductal Gray (PAG) of the midbrain could produce analgesia that was comparable in strength to 50 mg/kg of morphine (quite the dose)

​

• It could also inhibit the Tail-Flick Reflex.

​

• Why is the tail-flick significant?

Inhibiting the Tail-Flick means there must be a descending brain-to-spinal cord �pain-inhibitory system

• The tail-flick is a totally spinally mediated spinal reflex – no brain involvement. Disconnect brain and spinal cord and it still happens.

​

• If electrical stimulation of the midbrain can inhibit this reflex, it probably means that some system exists between the midbrain and spinal cord that can stop pain information at a very early point in the processing of pain.

And the plot thickens…

Huda Akil

• Huda grabbed every drug off the shelf and threw it at SPA.�
• One of the drugs was the relatively new (and at that time free) drug naloxone, a potent opiate antagonist (that is, it blocks the effects of opiates).�
• Naloxone could block analgesia (SPA) produced by stimulation of the PAG!!!�
• Since it couldn’t be blocking electricity, this suggested that brain stimulation could release endogenous chemicals that interacted with opiate receptors.

The PAG – One Source of SPA

Basbaum & Fields Model of Descending Pain Inhibition

Life was simple…

​

• The brain had an opioid-mediated descending brain to spinal cord pain inhibitory system.�
• BUT, to believe the simple story, you had to ignore the fact that labs couldn’t always replicate the effect of naloxone on SPA. �
• I noticed that in Akil’s work with some drugs, she got different results when she was/wasn’t near a certain nucleus in the PAG region, so…

​

​

​

I implanted stimulating electrodes along the midline that scattered above, through, and below that nucleus.

Dorsal vs. Ventral PAG Sites

Dorsal

Not blocked by Naloxone

No tolerance

No cross-tolerance with opiates

Ventral

Blocked by Naloxone

Tolerance

Cross-tolerance with opiates

But what about the connection to the spinal cord?

Raphe Magnus Lesions�Disrupt Ventral (opioid) not Dorsal

Agrees with Basbaum & Fields for opioid, �but non-opioid takes a separate, more lateral, path.

Opioid is opioid

Non-opioid is ???

Marijuana inhibits pain!

• Cannabinoid/anandimide receptors seem to be involved
• Block cannabinoid, block pain-inhibition from dorsal

You heard it here!

Stress-Induced Analgesia:�Almost Same Story, Start to Finish

• Was blocked by naloxone in some labs�
• Wasn’t blocked by naloxone in other labs�
• We found it was not an “it”…�
• There are opioid and non-opioid forms of SIA

Rotation-Induced Analgesia

Our “Big Fig”

Shock Intensity

Shock Duration

3 Types of SIA (at least)�Stress-Induced Analgesia

1. Brief opioid (relatively gentle)�
2. Brief non-opioid (relatively intense)�
3. Prolonged opioid

1. Blocked by naloxone, tolerance/cross�
2. Not blocked by nal, no tolerance/cross�
3. Blocked by naloxone, tolerance/cross

1. Non-”hormonal”�
2. Non-”hormonal”�
3. “Hormonal” – Pituitary/Adrenal

1. No immune suppression�
2. No immune suppression�
3. Immune suppression�

Pain Kills!

Pain – the 5^th vital sign!

Segue to Mark Breedlove

Tragically cut short by math.

Actually by…

The decimal point

Breedlove�The Nucleus Bulbocavernosus

And penile flips in anesthetized rats!!

He was a cartoon in Discover Magazine

2D:4D Finger Ratios are Related to Sexual Orientation in Female, but not Male Homosexuals

This triggered my finger-ratio phase.

Autism

The Snail Period

Snail Pain Organization:�Very Similar to Rats

Oooh – Pretty Green!

9-11

The end of Helix aspersa in Pennsylvania

Except for dinner…

Then, I Was Happily Wandering Descending Pain-Inhibition Posters at the Society for Neuroscience Meeting, Thinking Only of My Current (True?) Love: Pain...

Green – cells labeled from lumbar spinal applications of fluorogold (retrograde).

Red – cells labeled from applications of a second retrograde marker in the midbrain region.

Yahhh!!! I saw greens in auditory nuclei!!! (Trust me, they’re there.)

Now We’re Placing Fluorogold on the Dorsal Surface of the Cervical or Lumbar Spinal Cord and Looking for Retrogradely Labeled Cells in Auditory Nuclei

Boy, were we excited!!!

Cervical placement of fluorogold

With cervical placements, there were many, many labeled cells in the cochlear nuclei – here the tip of the ventral cochlear nucleus. Many less with lumbar.

Mostly Ventral Cochlear Nucleus

Also Labeling of Acoustic Nerve Neurons with Both Cervical and Lumbar Placements

But Non-Auditory Neurons that We Weren’t Interested in Were Labeled MUCH More Intensely

Raphe Magnus –

It’s prettier to look at if you don’t blow it up first.

This difference, combined with established wisdom saying that descending auditory projections don’t exist, causes us much consternation. I worry that our labeling is artifactual - permutations are being examined…

Breaking my oath,�we’ve started a breeding colony to look at environmental enrichment.�(or are we…)

Historical Enrichment

Modern Enrichment

We’re trying to get enrichment in a “normal” housing shoebox.

Not Disneyland

Igloo With Running Wheel

Is Exercise, the Running Wheel,�the Critical “Enrichment” Variable?�

Exercise May Be a Critical Element �of Most Enrichment Environments - �We’re Focusing on Exercise

Anxiety: �Elevated Plus Maze

Spatial Memory:�Morris Water Maze

Depression�and the Hippocampus

Everyone talks about serotonin but…

​

1. Reduced neurogenesis with depression
2. Exercise can increase neurogenesis
3. Can exercise help depression?

​

​

Depression Measures

• Learned Helplessness (related to long duration opioid stress-induced analgesia)�
• Swimming (time spent swimming versus floating)�
• Tail suspension (time spent “struggling”)

The End?

Research Collaborators

Roll the credits please…

Abelson, R.M.

Morley, B.J

Rios, D.

Potthoff, A.D.

Gage, P.

Perkins, F.

Giesler, G. J. Jr.

Urca, G.

Liebeskind, J.C.

Prieto, G.J.

Nahin, R.L.

Ryan, S.M.

Moskowitz, A.S.

Lee, A.

Chudler, E.H.

Lewis, J.W.

Weinberg, V.E.

Lewis, J.W.

Akil, H.

Maro, N.

Telep, B.

Carty, G. 

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Derr, S.L.

Griffiths, T.M.

Tomcho, T.J.

Myers, K.P.

Willi, J.P.

Newman, K.K.

Dilley, M.R.

Marzocco, S.S.

Mayne, T. J.

Brust, A.M.

Norcross, J.C.

Halgin, R.P.

Accardo, C.M.

Aboyoun, D.C.

Alford, B. A.

O'Brien, J.P.

Brennan, R.J.

Wheeler, R.A.

DeMarco, P.J.

Neary, S. T.

Jollie, C. L.

Quinn, J. J.

Carlo, M.A.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

D’Amico, M. A.

O’Donnell, B.

Mahometa, M.J.

Reid, R.S.

Baril, G.L.

Osmanski, J.J.

K.R. Herbert

Osmanski M.S.

Polowczuk L.A.

Maddern J.L.

Kelker M.E.

Peckins S.E.

Herbert K.R.

Bono M.E.

Maguschak K.A.

Donohue  J.M.

Lauer L.M.

Coluccio N.M.

Maysfield G.M.

Peel K.P.

Sublette N.A.

Stanik, C.E.

Yoder, K.M.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Gogas, K. R.

Kirtland, D. S.

Barba, C. A.

Ratzin, A. A.

Shavit, Y.

Sakihara, J.

Missar, C.D.

Gunn, K.H.

Cannon, B.J.

Thomas, B.L.

Utz, J.P.

Walsh, E.W.

Roat, D.B.

Liskowicz, R.J.

Levine, R.

Yirmiya, R.

Henry, R.E.

Bolan, E.A.

Iannone, V.N.

Dennis, S.A.

Weihbrecht, E.J.

O'Connell, R.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Terman, G.W

Depaulis, A.

Morgan, M. M.

Chickson, J.T.

Burns, W.K.

Frenk, H.

Baldwin, A.E.

Weihbrecht, J.G.

O'Neill III, J.G.

Colbern, D.L.

Dunstone, J.J.

Caldecott,-Hazard S.

Quinn, J. J.

Phillips, C. M.

Kyriss, K. M.

Hulse, H. M.

Sherman, J.E.

Chudler, E.H.

Pohlig, R.

Stapleton, J. M.

Fitzgerald, M.

​

​

​

Paths Taken, at Least Momentarily

• Audition
• Ear Wiggling
• Ear Rumbling
• The Acoustic Startle Pathway
• The Pinna Reflex Pathway
• Pinna Startle
• Early Auditory Relay Nuclei Projections to the Inferior Colliculus�
• Pain
• Pain-Induced Vocalizations
• Analgesia
• Anal-gesia
• Rotation-Induced Analgesia
• Electroconvulsive Shock-Induced Analgesia
• MSG-induced Destruction of the Arcuate Nucleus
• Raphe Magnus Lesions Disrupt Brain- and Stress-Induced Analgesia
• Body Region Shocked Does Not Define the Pharmacological Basis of Stress-Induced Analgesia
• Injury-induced sensitization to pain�
• How to Masturbate a Rat (You can’t, and they don’t vomit either.)�
• Enrichment
• Antidepressant – antioxidant
• Anxiety
• Pain
• Fear
• Memory
• Spatial
• Fear
• Anxiety
• Foraging

​

• Electromagnetic Field Effects on Sperm Motility�
• Autism - Prenatal Androgen Levels Reflected by Finger Ratios and
• SAT Performance
• Ball Toss Accuracy
• Adult Traits Related to Autism
• General Personality Traits (Big Five)
• Sexual Personality Traits

​

• Spinal Projections of Early Auditory Relay Nuclei�
• Cognitive Deficits Associated with Soccer (there are many)�
• Post-Decapitation Seizures�
• Epilepsy�
• Sensory Responses of Neurons in the Lateral Cervical Nucleus�
• Long Ascending Projections of the Substantia Gelatinosa and Subjacent Dorsal Horn in the Spinal Cord of the Rat�
• Opioid and Non-Opioid Forms of Brain Stimulation-Induced Analgesia�
• Opioid and Non-Opioid Forms of Stress-Induced Analgesia�
• Fear
• Neuroanatomy of fear-induced freezing
• When should you do extinction (get right back on the horse?)�
• Itch�
• Saccharine consumption (sweet preference) pain�
• Sex Difference in Noise Annoyance & Loudness�
• Factors in Choosing a Mate�
• Circannual Stress in Snails�
• Sexy 7 (Maybe 8)�
• Love Darts�
• Zah: The Ultimate Profane Statement (4 Letters and Gender-Specific)�
• Moon Illusion�
• Faith Healing�
• Animal Research�
• Birth Month and Belief in the Paranormal: Related to schizophrenia?�
• Who Keeps Diaries and Why�
• Sexual Dimorphism�