I'm loaning a friend my Vision Science book for her class in Visual Perception. I envy her this semester, taking Visual Perception with Stephen Palmer, and Mind & Language with George Lakoff. I remember when I was in those classes, and how clear it was that you were learning from two of the leaders in the field (and I mean that in the good way). She may also get the chance to study in a small neurology seminar with Rich Ivry. Ivry's great, not only because of his extreme knowledge (and ongoing research) in the field, but because he's easygoing.

Back when I took his Cognitive Neuroscience course (CogSci 127), I remember (and wouldn't you know, I've got the photos too) when he talked about Transcranial Magnetic Stimulation. Basically, a TMS is a solenoid that generates a very powerful, but highly focused magnetic field that disrupts the delicate electrical potentials within its reach.

The thing is shaped like a ping-pong paddle, with a wire going from the handle to a computer that controls the pulse duration and frequency. The flat paddle projects a disruptive field a few cenitmeters beyond its surface. Scientists use it to create temporary harmless brain lesions. Basically, this will stop a select few square cenitmeters of a person's cerebral cortex from functioning for under a second per pulse.

As we in the class are all amazed by this, he rolls out a cart with a laptop and a TMS paddle on it and asks his head TA if he could come to the front of the room. It sucks to be the GSI. But no, the TA was going to man the computer, while Ivry took the paddle in his own hand, placed it carefully on the right part of his skull (right forward parietal lobe, the motor cortex, a little off from the top, the part controlling the left arm and fingers), holds out his left arm, and signals to the TA.

Professor Ivry takes his role as an educator very seriously.

The class goes very quiet. Shuffling stops, pens stop writing, the 360 students in the room completely fixated on what's about to happen. A flashbulb goes off and 361 heads turn toward me as I sheepishly lower the camera and everyone starts laughing. Once everyone looks back to the spectacle-in-the-making, Ivry gives the sign and the head TA presses a few keys. Pulses accented by quick beeps pulse though the paddle, and every four seconds the professor's arm and fingers twitch. "Okay, now I'm going to concentrate on keeping my fingers absolutely still" he says, and there's absolutely no difference.

I snap another picture without a flash, just in case it looks better (it did).

It starts to dawn on some of the students that he could move the paddle a little along the motor cortex and affect other parts of the body, the face, the legs, the toes, and right next to toes on the cortex, the genitals. Scattered pockets of giggling ensue. Made bold by the professor's daring, a few students call out requests: "Can you put it at the back of your head?" (occipital lobe: temporary lack of vision for part of the visual field (not darkness, but a completel lack of awareness that it exists)), "Can you put it at the front?" (prefrontal cortex: temporary lack of personality), "Broca's! Broca's!" (Broca's Area: inability to formulate coherent words).

But no, even when a few students volunteered to be guinea pigs (err, monkeys. I think this thing could probably disrupt a whole guinea-brain at once, and that wouldn't be good) trying, no doubt, to remember where the pleasure center of the brain was. Besides, it wouldn't activate it, as an electrode would. It would just disrupt it anyhow.

I wonder if the grad students ever mess with the paddle after office hours.

Ahh, I miss Berkeley...