The Journal of Neuroscience, August 1, 2001, 21(15):5740-5751
Neural Correlates for Angular Head Velocity in the Rat Dorsal
Tegmental Nucleus
Joshua P.
Bassett and
Jeffrey S.
Taube
Department of Psychological and Brain Sciences, Center for
Cognitive Neuroscience, Dartmouth College, Hanover, New Hampshire 03755
Many neurons in the rat lateral mammillary nuclei (LMN) fire
selectively in relation to the animal's head direction (HD) in the
horizontal plane independent of the rat's location or behavior. One
hypothesis of how this representation is generated and updated is via
subcortical projections from the dorsal tegmental nucleus (DTN). Here
we report the type of activity in DTN neurons. The majority of cells
(75%) fired as a function of the rat's angular head velocity (AHV).
Cells exhibited one of two types of firing patterns: (1) symmetric, in
which the firing rate was positively correlated with AHV during head
turns in both directions, and (2) asymmetric, in which the firing rate
was positively correlated with head turns in one direction and
correlated either negatively or not at all in the opposite direction.
In addition to modulation by AHV, some of the AHV cells (40.1%) were
weakly modulated by the rat's linear velocity, and a smaller number
were modulated by HD (11%) or head pitch (15.9%). Autocorrelation
analyses indicated that with the head stationary, AHV cells displayed
irregular discharge patterns. Because afferents from the DTN are the
major source of information projecting to the LMN, these results
suggest that AHV information from the DTN plays a significant role in
generating the HD signal in LMN. A model is proposed showing how DTN
AHV cells can generate and update the LMN HD cell signal.
Key words:
dorsal tegmental nucleus of Gudden; lateral mammillary
nuclei; head direction cell; angular head velocity; nucleus prepositus
hypoglossi; directional heading; neural integration; vestibular system; navigation; spatial orientation
Copyright © 2001 Society for Neuroscience 0270-6474/01/21155740-12$05.00/0