Summary of Mahor Surgical Prcedures in Lisberger Experiments:
IMPLANTATION OF EYE COIL
Monkey’s head is placed in stereotaxic device, held in place by ear bars. Eye is sliced open with a scalpel, metal coil is cemented to the eyeball and the incision is stitched shut. Wires are run under the skin to a site on the top of the skull above the brow. Here, a site the size of a nickel has been “cleared” and screws implanted in the skull. The subcutaneous wires are pulled to the skull, soldered to a connector and cemented to the screws in the bone of the skull.
Purpose: to monitor eye position.
HEAD IMPLANT
Method 1 – used on most monkeys: Monkey’s head is placed in stereotaxic device. Scalp is sliced open and muscle and connective tissue is cleared away. Titanium plates (3 or 4) are placed on skull and holes drilled into bone for screws to secure the plates to the head. Head holding device (socket) is then cemented to plates and skin is sutured over the metal plates bolted onto the skull.
Method 2 – used on monkeys whose bone erodes “quickly” around the implant site. All tissue is cleared off the skull (skin, muscle, connective tissue) and extra bolts are drilled in. Then the skull is covered with dental acrylic cement.
Purpose: to bolt monkey by the head to his restraint chair so he cannot move his head during the Lisberger experiments. It also carries a pedestal to which vision-distorting goggles or spectacles are bolted for part of experiment.
CYLINDER IMPLANT
A circular, saw-like surgical instrument, known as a trephine is used to cut out disks of bone, usually from the skull) is used to cut a circular hole in the skull and expose the dura, or lining of the brain. Bolts are screwed into the skull around the circular opening. The steel recording cylinder is bolted and cemented to the site, filled with saline and antibiotic and capped with a plastic cap.
In some monkeys, Lisberger prepares another site for electrodes in the part of the brain called the flocculus (either of two small lobes on the lower posterior border of the cerebellum.) For this procedure, screws are placed in the skull, dental acrylic cement is placed on the skull and a drill is used to make an 8 mm hole in the skull. Gelfoam is placed in the hole and a plastic cap on top.
Purpose: To drive microelectrodes through the cylinder into the brain to record electrical activity of single neurons.
DURA PEEL
Irritation from putting electrodes through the dura [The tough fibrous membrane covering the brain and the spinal cord and lining the inner surface of the skull] and from the foreign head implant causes the dura to be covered with scar tissue. The monkey is anesthetized in his restraint chair in the lab, and scar tissue is peeled from the dura. The procedure “occurs dozens of times in a monkey”, approximately every two weeks.
Purpose: To remove scar tissue that prevents Lisberger from driving electrodes into the brain without breaking the electrodes.
Source: “Neural Control of Eye Movement: Cortical Plasticity Systems,” one of two protocol submitted by Stephen Lisberger and approved by the UCSF Committee on Animal Research. Obtained by In Defense of Animals through the California Public Records Act.
Related Links
- Main UCSF Stephen Lisberger Campaign Page
- What You Can Do
- Lisberger's Monkey Records
- IDA's response to NIH defense of Lisberger
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