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Electronic Letters to:
- BehavioralSystemsCognitive:
Benjamin J. Clark, Asha Sarma, and Jeffrey S. Taube- Head Direction Cell Instability in the Anterior Dorsal Thalamus after Lesions of the Interpeduncular Nucleus
J. Neurosci. 2009; 29: 493-507[Abstract] [Full text] [PDF]
eLetters: Submit a response to this article
Electronic letters published:
Interpreting lesion effects on head direction anticipation
- Matthijs A. A. van der Meer (15 January 2009)
Interpreting lesion effects on head direction anticipation 15 January 2009 
Matthijs A. A. van der Meer,
Post-doc
Department of Neuroscience, University of Minnesota, Minneapolis MN 55455Send letter to journal:
Re: Interpreting lesion effects on head direction anticipation
mvdm{at}umn.edu Matthijs A. A. van der Meer
An intriguing aspect of the data in Clark et al. is the observation that interpeduncular nucleus (IPN) lesions increase (by about a factor 2) the amount by which thalamic HD cells anticipate future head direction. Integration of such anticipatory time interval (ATI) data with modeling studies has been a useful tool in dissecting the HD system circuitry. An important question in this respect is whether anticipation in the HD system results from the same mechanisms responsible for updating the system in response to movement, or if the two are distinct.
Clark et al. find a dissociation of IPN contributions to the update mechanism (decreased accuracy if lesioned), and anticipation (increased if lesioned). This suggests not only that the putative motor contribution of IPN cannot be the source of HD anticipation, but moreover, that in the intact animal, such input serves to counteract anticipation originating from a different source. This interpretation is further supported by a previous report from the same group (Bassett and Taube 2005) showing that when animals are rotated passively, thalamic HD cells anticipate more than during active movement. Taken together, these data appear inconsistent with the proposal that HD anticipation might derive from motor efference copy, and instead support its generation from vestibular or network properties.
However, anticipatory time interval (ATI) data needs to be treated with caution. In particular, van der Meer et al. (2007) found a relationship between the dynamics of head movements and observed ATIs, where rapid, abrupt and high-frequency head movements are associated with little anticipation, and smooth movement with high ATIs. In order to increase confidence in the above interpretation of the Clark et al. ATI results, it would be helpful to know if there are any differences in head movements associated with IPN lesions that may account for the observed effect on anticipation.
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