The Lacrimal and its Effects
In a new study, researchers at the University of California, Los Angeles, report that they have shown for the first time that the lacrima, an appendage on the back of the skull, can exert a strong gravitational force.
The study is published in the journal Science Advances.
“The findings demonstrate that the lateral and lateral lobes of the lacramial apparatus are critical for the propagation of the force that acts on the frontal lobes,” says first author Andrew Tait, a doctoral student in the UCSB Department of Anatomy.
The researchers performed the experiment with a pair of young female monkeys and their mothers.
One mother received an injection of an experimental medication that activates the lateral lobar apparatus, while the other mother received no medication.
“In both cases, the injected drug caused the monkeys to feel a slight change in their posture, which was related to the force exerted by the lateral apparatus,” says lead author Sarah Hildebrandt, an assistant professor of anatomy.
The monkeys in the control group had a lower posture than the monkeys that received the medication, but not much of a difference in their overall level of body awareness.
The monkey in the experimental group that received no drug was, on average, much more aware than the control monkeys.
The scientists found that the monkey that received a drug for the lateral axis of the brain was more able to orient and follow its environment, which indicates that this region is involved in controlling movement.
“Our data suggest that this lateral axis might be a critical part of the locomotor control mechanisms that underlie the acquisition and use of new stimuli, such as novel odors,” Hildebrands says.
“It is likely that lateral movement is a primary mechanism in the acquisition of new behaviors, such that it is the neural substrate that regulates locomotion and learning.”
The researchers also found that it was not possible to find a direct link between the lateral lobe and the use of a new drug or the acquisition or use of the drug.
Rather, they found that, for a given stimulus, the lateral arm had a stronger gravitational force when the drug was applied.
In fact, the researchers found that a small amount of the injected medication increased the lateral limb’s gravitational force, but this effect was not enough to alter the animals’ behavior.
“If you take away the effect of the drugs, you can’t explain the observed differences in locomotor activity between the two groups,” says Hildebeards co-author Elizabeth P. Kravitz, a professor of neuroscience at UCSB.
“So we are really just asking, ‘Why?'”
Why do the monkeys in one group seem to prefer a drug to a control?
The researchers have yet to figure out why.
The mechanism for this behavior could be related to a particular type of neural pathway in the lateral lateral lobe, Kravits says.
In this pathway, neurons send information from the front to the back lobes, where the action of the spinal cord occurs.
This information may then travel to the spinal fluid, where it may then be released by the cells that reside in the ventral part of this pathway.
“This may explain why we saw a significant difference in the monkeys’ lateral limb behavior with drug treatment,” Kravts says.
The new research also raises an interesting question: Why are the lateral limbs of monkeys like those of humans?
“This is the first study that has shown that the front lobes are involved in aversive behavior, and yet these monkeys have no obvious response to aversive stimuli,” says co-first author Eric P. Pecore, a graduate student in Kravitts lab.
“I think this suggests a role for the medial lobes in learning and memory, but we have not yet shown that these mechanisms operate at a neural level.”
Pecores lab is investigating how the lateral muscles are recruited to control locomotion, as well as the role of specific neurotransmitters in these behaviors.
The research was supported by the National Institutes of Health (grants T32GM007169, T32E302054, T33GM082465, K08DK044082, T31R012318 and K07HL060189).
The authors have disclosed no relevant financial relationships.
©2017 American Journal of Anatomical Anthropology.