The Two Fear Channels

June 18th, 2016


Hoisted from a recent email thread with the estimable Jim Davies:

“You wrote to me once that the brain has two fear channels, cognitive and reactive. Do you have a citation I can look at for an introduction to that idea?”

So I didn’t have a citation off the top of my head, though I do now – LeDoux’s 1998 book The Emotional Brain – but I did remember what I told Jim: that we have two fear channels, one fast, one slow. The fast one is primarily sensory, reactive, and can learn bad associations which are difficult to unlearn, as in PTSD (post-traumatic stress disorder); the slow one is more cognitive, deliberative, and has intellectual fear responses.

It turns out that it ain’t that simple, but I was almost right. Spoiling the lead a bit, there are two conditioned fear channels, the fast “low road” and slow “high road” and they do function more or less as I described: the low road has quick reactions to stimuli, a direct hotline from sensory processing in your thalamus to the amygdala which is a clearinghouse for emotional information; the high road involves the sensory cortex and confirms the quick reaction of the low road. The low road’s implicated in PTSD, though PTSD seems to involve broader areas of brain damage brought on by traumatic events.

Where that needs tweaking is that there’s also a third fear channel, the instructed or cognitive fear channel. This allows us to become scared if we’re told that there’s a tiger behind a door, even if we haven’t seen the fearsome beast. This one relies on an interaction between the hippocampus and the amygdala; if your hippocampus is damaged, you will likely not remember what you’re told, whereas if your amygdala is damaged, you may react appropriately to instruction, but you might not feel the appropriate emotional response to your situation (which could lead you to make poor choices).

So, anyway, that’s the gist. But, in the spirit of Check Your Work, let me show my work from my conversation with Jim.

Ok, I have an answer for you (description based on [Gazzaniga et al 2002], though I found similar information in [Lewis et al 2010]).

There are two fear channels: one involving fast sensory processing and one involving slower perceptual information. Based on the work of LeDoux [1996] these are sometimes called the “low road” (quick and dirty connection of the thalamus to the amygdala, a crude signal that a stimulus resembles a conditioned stimulus) and the “high road” (thalamus to sensory cortex to amygdala, a more refined signal which is more reliable); both of these channels help humans learn implicit conditioned fear responses to stimuli.

This “low road” and “high road” concept was what my understanding of PTSD is based on, that individuals acquire a fast low-road response to stimuli that they cannot readily suppress; I don’t have a reference for you, but I’ve heard it many times (and it’s memorably portrayed in Born on the Fourth of July when veterans in a parade react to firecrackers with flinches, and later the protagonist after his experience has the same reaction). A little research seems to indicate that PTSD may actually involve events traumatic enough to damage the amygdala or hippocampus or both, but likely involving other brain areas as well ([Bremner 2006], [Chen et al 2012]).

There’s a couple more wrinkles. Even patients with amygdala damage have unconditioned fear responses; conditioned responses seem to involve the amygdala [Phelps et al 1998]. Instructed fear (warning a subject about a loud noise that will follow a flashing light, for example) seems to involve the hippocampus as well, though patients with amygdala damage don’t show fear responses even though they may behave appropriately when instructed (e.g., not showing a galvanic skin response even though they flinch [Phelps et al 2001]). This amygdala response can influence storage of emotional memories [Ferry et al 2000]. Furthermore, there’s evidence the amygdala is even involved in perceptual processing of emotional expression [Dolan and Morris 2000].

So to sum, the primary reference that I was talking about was the “low road” (fast connection from thalamus to amygdala, implicated in fast conditioned fear responses and PTSD, though PTSD may involve trauma-induced damage to more brain areas) and “high road” (slow reliable connection from thalamus to sensory cortex to amygdala, implicated in conditioned fear responses), but there’s also a “sensory” path (conditioned fear response via the thalamus to the amygdala, with or without the sensory cortex involvement) vs “cognitive” path (instructed fear response via the hippocampus, which functions but shows reduced emotional impact in case of amygdala damage).

Hope this helps!

Bremner, J. D. (2006). Traumatic stress: effects on the brain. Dialogues in clinical neuroscience, 8(4), 445.

Chen, Y., Fu, K., Feng, C., Tang, L., Zhang, J., Huan, Y., … & Ma, C. (2012). Different regional gray matter loss in recent onset PTSD and non PTSD after a single prolonged trauma exposure. PLoS One, 7(11), e48298.

Dolan, R. J., & Morris, J. S. (2000). The functional anatomy of innate and acquired fear: Perspectives from neuroimaging. Cognitive neuroscience of emotion, 225-241.

Ferry, B., Roozendaal, B., & McGaugh, J. L. (1999). Basolateral amygdala noradrenergic influences on memory storage are mediated by an interaction between β-and α1-adrenoceptors. The Journal of Neuroscience, 19(12), 5119-5123.

Gazzaniga, M.S., Ivry, R.B., & Mangun, G.R. (2002) Cognitive Neuroscience – The Biology of the Mind (2e) W. W. Norton & Company.

LeDoux, J. (1998). The emotional brain: The mysterious underpinnings of emotional life. Simon and Schuster.

Lewis, M., Haviland-Jones, J. M., & Barrett, L. F. (Eds.). (2010). Handbook of emotions. Guilford Press.

Phelps, E. A., LaBar, K. S., Anderson, A. K., O’connor, K. J., Fulbright, R. K., & Spencer, D. D. (1998). Specifying the contributions of the human amygdala to emotional memory: A case study. Neurocase, 4(6), 527-540.

Phelps, E. A., O’Connor, K. J., Gatenby, J. C., Gore, J. C., Grillon, C., & Davis, M. (2001). Activation of the left amygdala to a cognitive representation of fear. Nature neuroscience, 4(4), 437-441.

-the Centaur
Pictured: a few of the books I looked at to answer Jim’s question.

Check Your Work

June 18th, 2016


My brain’s filled with all sorts of tidbits I think I know: time is not fixed, the Earth is not flat, and the Sun doesn’t go around it on a giant chariot.

But people throughout history have believed a lot of crap – for over 2,100 years, people thought Euclidean geometry was a thing, that it was the only thing, to the point that mathematical history books are filled with an enormous amount of bullshit arguments on why parallel lines can never meet, arguments which, in a post-Einstein world in which we’ve measured the deflection of the light from the stars in the sky by the bending of space itself under the weight of the Sun, are obsolete and ridiculous. That isn’t to say tomorrow that scientists won’t find a use for a model of the world which embeds the bendy-wendy Einsteinian cosmos in a fixed Euclidean model of space and time, but it is to say that the idea that only Euclidean geometry is logically possible is dead wrong.

So, knowing that people can be wrong, and dead wrong, about things that they’re dead sure are so true they’ve mistaken them for logical tautologies, it’s worth taking out a little time, when you’re called upon to call up one of those little tidbits you think you know, to check your work.

Which is a way for apologizing for the next article on this blog, which will be a bunch of brain nerdery.

-the Centaur

Pictured: my recent efforts to revisit three things I think I know: how to construct stories, how to construct numbers, and how to construct cognitive architectures.

Skindancer in Sweden

June 15th, 2016


I think I’ve mentioned this on Facebook, but not here: sometimes real life lurks beneath the surface. I read what I write, both to myself and out loud; I have beta readers and editor and publishers; I follow the reviews of my books; I follow their sales; and I pay close attention when people mention they’ve seen or read or liked my books. And then something happens which exceeds your expectations – a friend going to the ICRA conference sent me this pic of a full copy of my Skindancer trilogy in a bookstore in Sweden:


It is an English-Swedish science fiction bookstore with an extremely complete collection … but still, my trade-paperback sized volumes from a midsize publisher are up there with mass-market paperbacks from the big N publishing houses. That means someone on the other side of the world … someone with no contact with me, someone with no contact with my publisher that I know of … decided to compile a list of urban fantasy series … and mine was included.

Wow. I’m honored. And a little bit shocked.

Must write faster.

-the Centaur

“Sibling Rivalry” returning to print

June 13th, 2016


Wow. After nearly 21 years, my first published short story, “Sibling Rivalry”, is returning to print. Originally an experiment to try out an idea I wanted to use for a longer novel, ALGORITHMIC MURDER, I quickly found that I’d caught a live wire with “Sibling Rivalry”, which was my first sale to The Leading Edge magazine back in 1995.

“Sibling Rivalry” was borne of frustrations I had as a graduate student in artificial intelligence (AI) watching shows like Star Trek which Captain Kirk talks a computer to death. No-one talks anyone to death outside of a Hannibal Lecter movie or a bad comic book, much less in real life, and there’s no reason to believe feeding a paradox to an AI will make it explode.

But there are ways to beat one, depending on how they’re constructed – and the more you know about them, the more potential routes there are for attack. That doesn’t mean you’ll win, of course, but … if you want to know, you’ll have to wait for the story to come out.

“Sibling Rivalry” will be the second book in Thinking Ink Press’s Snapbook line, with another awesome cover by my wife Sandi Billingsley, interior design by Betsy Miller and comments by my friends Jim Davies and Kenny Moorman, the latter of whom uses “Sibling Rivalry” to teach AI in his college courses. Wow! I’m honored.

Our preview release will be at the Beyond the Fence launch party next week, with a full release to follow.

Watch this space, fellow adventurers!

-the Centaur

Thrown off the horse and back into the saddle

June 10th, 2016


I have not yet finished dealing with the aftermath of Clockwork Alchemy, and yet I already find myself dealing with the prepwork for Dragon Con! But the good news is, once again, I’m a guest (well, technically, an “attending professional”):

Anthony Francis By day, Anthony Francis is a roboticist; by night, he’s an author and comic book artist. He wrote the Dakota Frost, Skindancer urban fantasy series including Frost Moon, Blood Rock, and Liquid Fire; edited the Doorways to Extra Time anthology; and published the steampunk anthology Thirty Days Later.

Yaay! Oh wait, that means I have to do panels. Aaaa!

Watch this space.

-the Centaur

Clockwork Alchemy Schedule

May 27th, 2016


Ahoy, fellow adventurers, if you’re interested in tales from a traveler who’s voyaged far and wide across the sea of unending stories, yet somehow returned to the shores we know, you can come listen to me talk at Clockwork Alchemy this year – I’m on four panels!

4PM: Overcoming Writer’s Block
Scheduled Presentation Time: Saturday 4pm – 4:50pm
Location: Author’s Salon (Monterey Room)

10AM: Writing Victorian Sci-Fi
Scheduled Presentation Time: Sunday 10am – 10:50am
Location: Author’s Salon (Monterey Room)

12 Noon: The Science of Airships
Scheduled Presentation Time: Sunday Noon – 12:50pm
Location: The Academy (San Martin Room)

2PM: Organizing an Anthology
Scheduled Presentation Time: Sunday 2pm-2:50pm
Location: Author’s Salon (Monterey Room)

I’ve given the “Science of Airships” before, and have done panels similar to “Writing Victorian Sci-Fi” and “Organizing an Anthology”, but “Overcoming Writer’s Block” I’ve not presented before to a public audience, so it should be interesting!

Come check it out!

-the Centaur

At Clockwork Alchemy 2016!

May 27th, 2016


Greetings, fellow adventurers! At long last, that time has rolled around again – Clockwork Alchemy, the Bay Area’s premiere steampunk convention. I’ll be here this weekend, most importantly for the launch of THIRTY DAYS LATER!


SO this year blogging every day was supposed to be a thing, but life is more important, and after taking care of my mom after her knee surgery, being there for my wife, and doing a good job at that thing I do that keeps a roof over our heads and food in the cats’ bellies, the next most important thing was … well, not 30DL, it was THE CLOCKWORK TIME MACHINE!


But that ain’t out yet, as it is still in copyedit. We may go another round on this one. Whatever. I want this book to win the Hugo and I trust my editor, so we’re going to work on it and Get It Right. But AFTER making sure my editor did not send ninjas to have me killed, the next most important thing was launching THIRTY DAYS LATER on time!


THIRTY DAYS LATER is Thinking Ink’s first full length fiction anthology, and we wanted to get this one right, or at least not so wrong that all the books were gone. Now that I am at the con with a giant pile of books, at last, I can breathe easy.


Oh, and I can finish my slides for Saturday’s presentation. Aaaa!

-the Centaur

Beyond the Fence

May 20th, 2016


Hooray! Thinking Ink Press has a new book out, BEYOND THE FENCE, a collection of short stories by Marilyn Horn! We’ve just got the proof now, but the proof was approved, and we’ll be putting the book into distribution SOON! Also, the art’s by my wife, Sandi Billingsley, and we got a very nice print from Fracture Me of the front cover art:



-the Centaur

Finnegan’s Firewall Flashcard

May 19th, 2016


Wow, something awesome just happened. Our publishing company, Thinking Ink Press, independently invented the idea of a postcard short – a flash fiction story on a postcard – and a new one has just been published which really ups the ante in the genre with its postmodern take on a postmodern book, illustrated with a mashup of The Book of Kells and a Nook!

Finnegan’s Firewall: Awesome art by my wife Sandi Billingsley, great design by Keiko O’Leary, cool story by David Colby, all in a postcard! Right now you need to get this in person from Thinking Ink, but we’re working on making it possible for you to check it out!

-the Centaur

Two Jeremiah stories reviewed on Publisher’s Weekly

May 19th, 2016

THIRTY DAYS LATER was reviewed on Publisher’s Weekly, and my two stories got a great review:

Each [story in THIRTY DAYS LATER] is broken into two separately titled parts, with events in the second part unfolding 30 days after those in the first. Anthony Francis, in “The Fall of the Falcon/The Rise of the Dragonfly,” uses that interval to work a crafty time-travel paradox into a futuristic tale of “infectious Foreign gearwork” run amok.

THIRTY DAYS LATER officially comes out June 1st, but you can order it now on Amazon! Check it out!