Neurology

When we look at it from the outside, the brain appears to be composed of two major regions: the larger cerebrum and the smaller cerebellum.

In this brain photograph--which, if it were still connected to its eyes, you would see that you are viewing it from the left side--the cerebrum is the larger region, superior to (above) the smaller cerebellum, which has been stained a light purple color.

Orientation

Source: http://upload.wikimedia.org/wikipedia/commons/a/a7/Cerebellum_NIH.png accessed 16 December 2012

The cerebrum controls the processing of sensory input, complex cognitive processes such as using language and decision-making (such as consciously deciding to move skeletal muscles), and memory, among many other things. We'll talk about it later in its own dedicated post.

The cerebellum, on the other hand, tends to operate with different aspects of movement than the cerebrum does, at an involuntary or unconscious level. Its most well-understood function is in controlling aspect of movement that we don't think about consciously, such as coordination, balance, and motor control.

Loca, the pug who couldn't run, shows what happens when the cerebellum is damaged or otherwise impaired--what you see in this video appears to be some kind of damage to the cerebellum that permits her to walk relatively normally, but severely disrupts her running.

You can use Loca as a mnemonic (a memory aid) to remember the functions of the cerebrum compared to those of the cerebellum--watch her movement, coordination, balance, and motor control as she tries to run, and you'll see what happens to those functions when the cerebellum doesn't work quite right.

Yet, as far as we can see from the video, there is no indication of any disorder of the cerebrum--she decides to run at appropriate times, when other dogs are running and playing.

The decision to run--made in Loca's cerebrum--seems perfectly normal, at least, as far as we can tell from a short movie.

It's the non-voluntary parts of the running, such as her balance and her coordination, where the difficulty lies. And those non-voluntary aspects of movement go back to her cerebellum.

Scope of practice note

I cannot diagnose, but as a anatomy/physiology teacher, Loca's movement disorder looks to me like cerebellar damage or impairment of some kind.

I checked with my cats' veterinarian, Dr. Davis, to make sure that I wasn't overlooking something that a clinician would see right away.

As an ethical practitioner, she would never definitively diagnose any animal only at a distance through a video alone, without an examination and a thorough history, but she agrees that--as far as we can see from the small sample contained in this video--the way that Loca runs is certainly consistent with some type of condition in which the cerebellum is damaged.

Cultural note

There is a word used for emphasis in the video which is a very strong and emphatic curse or swear word in American English.

In Irish English, on the other hand, the word "feckin" is used much more easily and casually by many people, and is not nearly so shocking as the American English equivalent is in context.

You should know that before you listen to the video, or show it to someone else, so that if strong language is something you want to avoid, you're not taken by surprise.

cheers, to Anne Davis, and to Loca and her family!