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Hiatus

After a few weeks of denial, I’ve decided that I need to announce a blog vacation. I’ve just started graduate school and need a bit of time to get settled in before I can put the time in to do the blog (and you, dear readers) justice. I’ll be back, I’m sure, some time this year.

Until we meet again, stay classy and thanks for reading!

Encephalon #88 is out!

Head on over to Cognoculture for the 88th edition of Encephalon, the blog carnival dedicated to psychology and neuroscience. There’s lots of great stuff there.

Thanks for reading!

The Tentacled Get-down

Man, things have been busy. I guess that’s what grad school is supposed to be like, right?

In any case, since you’re using the internet, I’ll assume you’ll be interested in a bit of graphic sexual content. I’ve talked about various aspects of cephalopod reproduction over the past year, but after stumbling across a few good videos last night, I decided to forgo all that mumbo-jumbo and let the squishy critters themselves do the talking (aided by a few humble narrators):

First, we have a great shot of some Pacific Market Squid in a mating aggregation:

Octopuses, being more solitary animals, tend to do things one-on-one, like in this intimate encounter:

Cuttlefish, last of all, mate in the same way that they do everything; that is, looking like the coolest things on the planet. The species in these videos (the Australian Giant Cuttlefish) have some neat courtship rituals, where they show each other certain skin patterns before snuggling up. This next clip is a long one (14 minutes), but is worth the investment:

This last one’s from the BBC – it’s the same species doing most of the same things, but with a bit of narration:

One final observation: the choice of soundtrack for these videos is critical. For example, triumphant orchestral music = wonderful, while the cameraperson breathing through a SCUBA = a bit creepy.

Thanks for reading!

To see or not to see – Image processing (or not) in the cephalopod retina.

Cephalopods use their vision a lot; it’s a big part of how they orient themselves in the water, hunt, and recognize predators and each other. It makes sense, then, that they have particularly well-developed eyes. In fact, they are the only invertebrates to have camera eyes. Camera eyes are eyes that focus an image on the retina, which transmits the image to the brain where it can be used to help the animal get around, find food, and whatever else it needs to do. Like cameras, these eyes can focus on different things – they focus in a different way than the eyes of vertebrates, though. Vertebrate’s eyes focus by changing the shape of the lens, while the eyes of cephalopods focus by moving the lens closer to or farther from the retina.

Drawing of a cephalopod eye and the optic lobe in cross-section, from Young 1962

So, cephalopods have these big fancy eyes – once light hits the lens, it forms a well-focused image on the retina. What happens then? When light hits the retina, it causes specialized nerve cells called photoreceptors to send electrical signals through other cells in the retina and the optic nerve to the brain. Along the way, these signals are converted into information that the brain can use to put together a picture of the world. For example, this information allows the animal to identify objects, boundaries, and features of their environment – something that is helpful to the organism, as this lets it identify things like sources of food or predators that might hurt it.

I am going to talk more about cephalopod vision in a moment; to get there, though, I want to explain a few things about the way vision works in you and I. Early on in the process, the visual system starts to turn the raw image from the eye into information about the environment. To understand this process, let’s think about something familiar – a computer screen. A computer screen displays an image by changing the changing the amount and color of light that is projected by each pixel. You can look at this information in different ways: at the most basic level, you could look at a list of the brightness and color of each pixel. This information would be complete, in that it would represent everything on the screen faithfully, but it wouldn’t be very useful (unless you can remember a list of a million numbers and then imagine a picture based on them, which I sure as heck can’t.) You could write a program that would take this raw information and recognize different features that are being displayed on a screen; for example, you could write a program to recognize regions of the display that were high contrast, or exceptionally bright, or a specific color, or a specific shape. This would tell you a little more about what was on the screen, but it wouldn’t actually be very useful for most things; these sorts of tools would give you a list of statements like “there is a white rectangle in the center of the screen and there are small black objects within this square.” The way we analyze what’s on a computer screen takes it a few steps further – our eyes, of course, take in light from each pixel, but then our brains analyze it into features, shapes, objects, and patterns. These pictures of the environment somehow get mixed in with our memories and thoughts, and we can get an idea of what’s going on in the environment – for example, I can say “there is a word processer open on my computer screen, and there is an unfinished blog post in it.” We often think of the brain as the place where things like this happen, but in fact, our nervous systems start interpreting the information from the visual field before it gets to our brains.

As you can see in the little diagram below (you can click it for a bigger version), the retina, the part of the eye that sits at the back and detects light, is made up of a bunch of layers of cells. Out of all of these, the cells that actually sense light (the photoreceptors) sit way at the back. Light passes through all the other cell layers, is picked up by the rod and cone cells, and then information about the light is passed back through the layers of the retina until they reach a layer of cells called “ganglion cells”, which send the information to the brain through the optic nerve. It’s easy to see that there’s a lot more to the retina than just picking up light – all those other cell layers must be there for a reason, right?

It turns out that by the time information is sent from the retina to the brain, it has already been processed from raw information about light entering the eye into a simple picture of the environment. If you look at the electrical activity of neurons in the optic nerve, which carries information from the eye to the brain, you find that these cells don’t simply respond to points of light like photoreceptors do. They respond to more complex things, such as a dark spot on a light background, a light spot on a dark background, the edges of an object, or movement in a specific direction. Each ganglion cell (these are the cells that make up the optic nerve) is programmed to respond to features of a certain size and position in the visual field. Before information about the visual field even leaves our eyes, it is processed a few steps towards a useable picture of the environment.

(If you are interested in reading more involved stuff about retinal ganglion cells in mammals, check out this great link.)

In octopuses, the same sort of process must go on – after all, the information from the eye has to get passed on to the brain somehow, so that the brain can use it. This image processing doesn’t go on in the retina, though; it takes place in the brain itself.

J. Z. Young was a scientist who studied the octopus brain extensively, and he found that when he cut the optic nerve of the octopus the photoreceptor cells in the eye died – along with his other observations, this indicates the the photoreceptor cells in the octopus’s eye send information straight to the brain, with no other cells in between (in a vertebrate – a mouse for example – cutting the optic nerve would make retinal ganglion cells die, but would spare photoreceptors, because they don’t actually extend outside the retina.)

Young’s observations weren’t made in a vacuum – they were supported by other work as well. Two year before his paper on the optic lobe of the octopus, Edward MacNichol and Warner Love had published a study in which they made electrical recordings from a squid’s optic nerve as it left the eye and found that the signals it sent in response to light shining on the eye looked like those of a simple photorecptor rather than the more complex signals that you would find if you recorded from a vertebrate’s eye.

Dr. Young also noticed that the part of the brain that these cells send information to, the optic lobes, have layers on the outside of them that look like the image-processing layers of the retina, and probably have the same function: to take the raw information from the photoreceptors and start to identify features in the environment. In fact, he was so convinced that the outer layer of the octopus’s optic lobe was doing the same thing as our retinas that he referred to it as the “deep retina”.

So what happens to the information after that? One (relatively) easy way of asking this question is to figure out where the optic lobe sends connections to, and where it gets connections from. J. Z. Young’s work gives us answers to these questions – sort of. In his 1962 paper on the octopus optic lobe, he lists all the places that nerve fibers from the optic lobe end up, and it’s most of the brain! This makes sense, though, when you think about all the things that octopuses use visual information for – they use it to guide their movement through the water (so the optic lobe and the parts of the brain that control the movement of the arms need to communicate with each other); they use visual information to figure out what colors and/or patterns they should display on their skin (so the optic lobe and the chromatophore lobe, which controls the colored organs in an octopus’s skin, need to communicate with each other); the octopus uses visual information to learn where and what things are (so the optic lobe and the vertical lobe, which is involved in memory, have to communicate with each other) – the list goes on, but you get the idea. After it gets to the optic lobe, information from a cephalopod’s eye is sent all over the place, which makes its paths much more difficult to trace. You imagine can that as we follow the flow of information from the eye, it branches out like a tree, getting more and more spread out and finely divided as it moves through the brain to whatever its destinations are. While we may not be able to follow it this far at the moment, as we get better and better at figuring out how brains work and put more and more time into studying them, it seems likely that we’ll figure out what those destinations are.

This is a sometimes useful, but ultimately wrong way to think about how information from the senses makes its way through the brain – in truth, it has no real destination. The brain’s main job is to control behavior, and so there’s no place within the brain where information from the senses gets to and then stops. The brain takes in information from the senses, and uses it to guide behavior – in a sense, then, the final destination of the information any neuron sends into the brain is a behavior. One can imagine the same tree-like structure of signals but in reverse to describe the flow of information from the brain into a behavior; at its most basic level, a behavior is just a specific sequence of muscle contractions. However, if we follow the flow of information backwards through the nervous system, we’ll find more and more neurons that play a part in controlling that behavior. As we go further and further, each individual neuron, each bit of information, will presumably play a smaller part in the overall behavior. If we kept following the branching tree, we would eventually end up so far away from the starting point that it would be hard or even impossible to figure out how we had gotten there – just like we had picked a random cell in the brain and said “what does *this* cell do?” If it’s a cell that’s particularly close to a certain sensor (like the ear) or a certain behavior (like the movements of a dancer), we have a good shot at figuring out pretty much exactly what it does, but there’s still a big area in the middle where it is much harder to figure out what different groups of neurons are doing and what effect they have on behavior. This is as true for cephalopods as it is for humans, but is part and parcel of studying the brain – when we try to understand something so complex, we have to expect some big question marks to pop up.

Thanks for reading! See you next week!

ResearchBlogging.org MacNichol, E., & Love, W. (1960). Electrical Responses of the Retinal Nerve and Optic Ganglion of the Squid Science, 132 (3429), 737-738 DOI: 10.1126/science.132.3429.737

Young, J. (1962). The Retina of Cephalopods and Its Degeneration After Optic Nerve Section Philosophical Transactions of the Royal Society B: Biological Sciences, 245 (718), 1-18 DOI: 10.1098/rstb.1962.0004

Young, J. (1962). The Optic Lobes of Octopus vulgaris Philosophical Transactions of the Royal Society B: Biological Sciences, 245 (718), 19-58 DOI: 10.1098/rstb.1962.0005

The abyss stares back into you…

One of the things I like about divers’ videos of cephalopods is that you often find the animals intently investigating the people filming them, and so the video is never an observation of the animal as much as an interaction with the animal. Check out these guys:

Thanks for reading! I’ll be back next week with a meatier post (on vision no less, one of my favorite subjects!)

Encephalon #87 – Memorial Day Edition

Welcome to our Memorial Day picnic … I mean, blog carnival! I guess I’ve just got food on the mind. In any case, the neuro- and psycho-blogosphere has been serving up delicious treats for you all month. Try a bite of some of these, and let me know how they suit you:

Ariel casts out Caliban – Eric Michael Johnson takes a look at the history of anthropological ideas surrounding human aggression, exploring the hypothesis that humans are special because we love to kill; we “naturally [enjoy] the destruction of other creatures.”

Hegarty on the Rorschach & Sexuality – Over at Advances in the History of Psychology, Jacy Young comments on a video by Dr. Peter Hegarty discussing the use of Rorschach test during what a “dark time in the history of psychology” – the period when clinical psychologists regarded homosexuality as a disorder (officially, this lasted until 1975, when the American Psychological Association declared that they did not consider homosexuality a disease anymore.)

Supertouch – Zen Faulkes discusses research exploring the truth of something we all thought we knew – when somebody loses one sense, do their other senses become more sensitive to compensate for it? Read on and find out!

Dodging the one-sided approach to neuromarketing – Thomas Ramsøy takes on the negativity that faces neuromarketing (the use of neurological tests and information to design and implement marketing) in popular discussion, pointing out the positive side of the field – especially its applications to research on the brain.

When the Microscope Goes Digital – Khalil Cassimally runs down the history of microscopy, an important tool for understanding the brain, and explains why traditional microscopy is pretty much dead as well as what killed it.

Knowing spontaneity when you hear it – Janet Kwasniak explores how we can tell whether somebody is reading or if they are coming up with speech spontaneously – something we all do that psychologists are trying to understand.

Thanks for reading! Next month’s edition will be hosted over at Cognoculture, so don’t forget to send your submissions to Taylor Burns at cognoculture (at) gmail (dot) com, or on twitter @teaburns .

Send me posts for Encephalon!

Though I love to write about cephalopods, my wife and I will be moving to Detroit over the next two weeks, and so I almost certainly won’t have time to post much.

In the meantime, don’t forget to send me your submissions for the Encephalon Blog Carnival – it’ll be hosted here at the end of May. Send me URLs on twitter (@Cephalover), leave them as a comment on this post, or email me at mike (dot) lisieski (at) gmail (dot) com .

I’ll see you in a few weeks!

Cephalopod links for your busy lifestyle

Ok, ok, it’s really more about my busy lifestyle. I’ve no time for a proper post today (I’ve got a Hindi exam tonight, and a pharmacology exam to study for,) so I thought I’d at least bring you some ceph-related Monday reading. There’s a bunch of cephalopod-ey topics getting talked about on the web these days:

You may have heard about some recent research on how noise can damage cephalopods’ statocysts (organs they use for balance and possibly hearing.) In case you weren’t convinced that oil harvesting was killing the ocean, this research has now been cited to argue that seismic surveying (the use of noises reflected off of the sea floor to figure out what is on/in the sea floor) by oil companies kills sea life.

In Detroit (where my wife and I will soon be living,) it is a tradition to throw (dead) octopuses onto the hockey rink whenever the local team, the Redwings, plays. The NHL doesn’t like this practice (citing variously danger to players from debris on the ice, a lack of professionalism, and other reasons.) Last Tuesday, a dude was arrested and fined for disorderly conduct for chucking a ceph at a Redwings game and (more interestingly), is ready to fight for what he sees as his cultural heritage:

“I pleaded not guilty, of course,” Graves said. “I’m going to fight for this tradition. And so, I have to come back in July for a trial, and I’ll be lawyered up.”

(As an aside, can you guess what fans of the San Jose Sharks throw on the ice? You guessed it.)

A lot of the recent interest in cephalopods is due to their skin; the US military (naturally) would love to figure out how to mimic its ability to change color at will. Towards this end, they’ve given a $6 million dollar grant to a group of researchers (including Roger Hanlon, a long-time cephalopod researcher) to figure out how cephalopods work their color-changing magic and then figure out how to mimic it. Besides the obvious military applications, though, there are other possible spin-offs, Hanlon said in an interview

“Some (of the applications) are as simple as heating and cooling things by absorbing or reflecting radiation,” he said. “Detroit can make cars that change color; fashion designers can make dresses that change pattern — highlight of the cocktail party!”

(Danna Staaf has a great piece up about squid skin; it’s well worth your time to check out.)

A movie about a giant squid is one of six science-based films to receive funding at the Tribeca Film Festival.

On the trail of science-based management of commercial squid fishing, scientist Teresa Johnson talks about how scientists and fishermen should work together.

Finally, there will be live squids aboard the last flight of the space shuttle Endeavor. Read Danna’s great write-up of this story over at Squid-a-Day.

Man, all that reading was hard. Let’s look at something cute:

(This digging behavior, by the way, seems to one of the few fixed action pattern-like behaviors seen in cephalopods – source)

Thanks for reading!

“I Know My Neighbour: Individual Recognition in Octopus vulgaris”

Most species of shallow water octopuses appear to be pretty solitary animals. They live in dens and venture out from them to hunt or find mates; defending these dens and getting busy are the only social interaction that many species of octopuses are observed to have in the wild. I like to think of them as the curmudgeons of the reef environment, keeping to themselves because that’s just the way they like it.

Keep movin', buddy; there's nothing to see here. (Photo by algaedoc)

It might surprise us, then, to learn that Elena Tricarico and her coworkers, working out of the Stazione Zoologica in Naples, just published a paper arguing the octopuses (of the species Octopus vulgaris), can recognize other individual octopuses. While it’s clear that this ability might be important to more social cephalopods (like squids, which form schools), what good could it do for a species with such a hermit-like existence?

It turns out that keeping to one’s self in an area where there are lots of other organisms around requires some social skills – you have to know a little about the folks around you and what behavior to expect from them. For example, if you see the same animal patrolling an adjacent territory each day, it doesn’t do much good to make a huge fuss over it all the time. If you have your territory, and she has hers, it behooves you both to be able to recognize each other so that you don’t waste time and energy chasing off somebody who isn’t actually going to cause you any problems (this is called the “dear enemy” effect.) On the other hand, if a wandering octopus comes through looking for a good nesting site, it would be useful to be able to tell that he’s a stranger so that you could drive him away and keep him from taking over your territory. Thinking about it in these terms, it makes sense that the ability to recognize other octopuses could be a useful ability to have.

To test whether octopuses could do this, Tricarico and coworkers divided up their experimental octopuses into two groups; in one group, pairs of octopuses were housed with a clear divider between them, so that they could see their partner, while in the other group the octopuses had an opaque divider. After letting the octopuses either see or not see each other for 3 days, they watched how these pairs interacted with each other when they were put into the same test tank for 15 minutes. It turns out that pairs that had seen each other before avoided each other more, touched each other less, and spent a longer time ignoring each other when they were placed in the same tank than pairs that had been separated by the opaque divider.

This alone isn’t enough evidence to conclude that octopuses can recognize other individual octopuses – after all, the pairs that could see each other might just be getting used to being around any octopus. To test whether the octopuses had learned to recognize their specific partner or just gotten used to the presence of other octopuses, the researchers did one more test – they put the octopuses back in the test tank, but this time, they put some of them in with the familiar octopus they had been seeing throughout the experiment, and some of them in with an octopus they had never seen before. What they saw was this: when octopuses were placed with another octopus that they were familiar with, they touched each other less, avoided each other more, and their interactions were shorter than when they were placed with unfamiliar octopuses. It looked as if the octopuses had learned to recognize their partner, and responded differently to them than to a strange octopus.

Like all good experiments, this one begs plenty of questions: can octopuses tell who individuals are, or do they just categorize other octopuses as familiar or unfamiliar? Does their ability to discriminate other individuals imply some sort of social cognition, and of what sort (I’d argue that it suggests only very basic social cognitive skills, but opens the door for more investigation,) and, finally, do I need to worry that someday, the octopuses will learn to recognize ME?

That's right, buddy, I'm looking at YOU. (photo by Rowland Cain)

Thanks for reading! I’d like to point out that I took the title of this post directly from the paper it discusses; it was such a good title that I couldn’t think of anything more fitting.

ResearchBlogging.org Elena Tricarico, Luciana Borrelli, Francesca Gherardi, Graziano Fiorito (2011). I Know My Neighbour: Individual Recognition in Octopus vulgaris PLOS One : 10.1371/journal.pone.0018710

Encephalon #86 is up!

Over at In the News Karen Franklin, a blogger who focuses of forensic and legal psychology, has brought us the 86th edition of Encephalon. Head on over there for a recap of the scientific mysteries that were covered in this month’s neuroscience and psychology blogging. Brilliant job, Karen!

I need hosts for May and July (also all the months thereafter) – please let me know if you would like to host an edition (I promise it’s not too hard)! Leave a comment here or hit me up on twitter @cephalover.