Scientists doing the right thing: Malfunctioning lab equipment leads to retraction of neuroscience paper

For the second time inside of a week, we come to praise scientists who did the right thing when they realized their lab equipment or reagents weren’t performing as expected.

Here’s the retraction of a 2011 paper in Cerebral Cortex:

The retraction of the article “AREAL DIFFERENCES IN DIAMETER AND LENGTH OF CORTICOFUGAL PROJECTIONS (Cereb. Cortex (2011) first published online August 8, 2011 doi:10.1093/cercor/bhr183) was initiated by the authors, motivated by the legitimate suspicion that the thickness of the sections, instead of 60 μm was 34 μm, was due to a recently discovered malfunction of the microtome. Two of the collaborating laboratories are currently, independently, proceeding to verifications. If the malfunction were to be confirmed, the lengths of some of the pathways, those with pronounced anteroposterior trajectories, in particular those originating from striate and extrastriate areas, would have to be corrected. The computed transmission delays would need correcting as well. The new version will be re-reviewed by the original referees.

Here’s the original abstract of the paper, which has been cited twice, according to Thomson Scientific’s Web of Knowledge:

Cortical areas differ in the size and distribution of neuronal cell bodies, density, and distribution of myelinated axons, connections, and functional properties. We find that they also differ in the diameter of long corticofugal axons, with the thickest axons originating from primary motor, somatosensory, and visual areas and the thinnest ones from prefrontal and temporal areas. Since diameter is proportional to axonal conduction velocity, it can be inferred that action potentials issued from the different areas will be relayed to their targets at different speed. Conduction delays also depend on conduction distance. By computing conduction velocity and conduction distances, we found the longest conduction delays for the primary visual and temporal areas and the shortest for the premotor, primary motor, and somatosensory areas, compatible with the available electrophysiological data. These findings seem to establish a new principle in cortical organization relevant to the pathophysiology of neurological or psychiatric illnesses as well as to the speed of information processing in cortical circuits.

As we wrote last week of another case:

They say that a poor workman blames his tools. If you’re a scientist and you discover your tools don’t do exactly what you thought they did, however, the right thing to do is let other scientists relying on your work know.

Update 10:15 a.m. Eastern, 5/2/13: Corresponding author Giorgio Innocenti tells us:

I started measuring distances along the Antero-Posterior axis of the brain and realized that they did not match with the published brain atlas of the monkey brain.

Then I measured the thickness of the sections and finally the advancement of the microtome with the machinist of this institution.

The error implied that some of the axonal pathway lengths we had measured, were overestimated. It was a tremendous amount of additional work to correct everything.  Fortunately the error had only very minor consequences on the results.

Unfortunately the old measurements still drag in my database and I have to constantly watch not to be fooled by them.

PS  I guess many scientists have constant nightmares about possible mistakes in their data collection.