Regional (¹⁴C) 2‐deoxyglucos uptake during vibrissae movements evoked by rat motor cortex stimulation

Abstract

Repetitive left mystacial vibrissae movements were produced by electrical stimulation of right motor cortex (MI) were a bipolar electrode in the alert, unanesthetized rat. Regional increases of (14C) 2-deoxyglucose (2DG) uptake were mapped autoradiographically during these left vibrissae movements. Uptake of 2DG increased in a 2-4-mm-diameter area about the stimulating electrode in right MI and in a smaller region in left MI cortex. Columnar increases of 2DG uptake occurred bilaterally in somatosensory cortex in the face region of somatosensory cortex (SI). Bilateral increases of 2DG uptake occurred subcortically in dorsolateral caudate-putamen (CP) and subthalamic nucleus. Primary right-sided increases of 2DG uptake occurred in other basal ganglia structures including dorsal globus pallidus (GP), posterior, entopeduncular nucleus (EPN), ventrolateral substantia nigra pars reticulata (SNr), and anterolateral substantia nigra pars compacta (SNc). Uptake of 2DG increased on the right side of the following thalamic regions: much of the ventrolateral (VL) nucleus, particularly dorsally; the anterodorsal reticular nucleus; dorsolateral posteromedial (POm) nucleus; the ventromedial nucleus; and dorsolateral parafasicular nucleus. The anterior and ventral posterior portions of VL were not activated. Caudal to thalamus right-sided 2DG uptake increased in the medial, ventral, and lateral pontine nuclei, deep layers of superior colliculus, lateral deep mesencephalic nucleus (DMN), and nucleus cuneiformis (NCU). UPtake of 2DG increased in right rostral parvocellular and red nucleus in a few animals. Discrete portions of the right internal capsule and right medial pyramidal tract increased 2DG uptake during MI stimulation. Uptake of 2DG increased on the left side of the brain during right MI stimulation in the left lateral nucleus (NL) of cerebellum and in several discrete regions of left cerebellar hemisphere granule cells including anterior paravermis, lobulus simplex, crus II, and the paramedian lobule. Uptake of 2DG increased in left nucleus of the spinal tract of the trigeminal nerve (ntV) ventrally in subnuclei interpolaris and oralis. Left lateral portions of the facial nucleus were activated in a few animals. The lateral portions of the facial nucleus are known to project to vibrissae musculature. All of the above structures may be involved in the motor-sensory processing responsible for vibrissae movements. Regions not previously suggested to play a major role in vibrissae movements include DMN and NCU. Though NCU has been called the "locomotor center" it may play a role in facial movements as well. Polysynaptic activation of GP, EPN, NL, and cerebellar hemisphere occurred since no connections between MI and these regions exist. A pathway from ntV to POm to MI and SI is suggested to provide proprioceptive input to motor-sensory cortex from the moving vibrissae since neither the principal trigeminal sensory nucleus nor the ventrobasal nucleus of the thalamus increased 2DG uptake during MI stimulation.

Angular Tuning Bias of Vibrissa-Responsive Cells in the Paralemniscal Pathway

“…Many of these cells likely exert an inhibitory function, as suggested by the high density of GAD-expressing cells in this subnucleus. Thus, because the SpVi [but not the principal trigeminal nucleus (PrV)] exhibits a marked deoxyglucose uptake during whisking (Sharp and Evans, 1982;Jacquin et al, 1993), GABAergic intersubnuclear projecting cells stand as potential candidates for gating the sensory stream associated with self-generated vibrissa motion in the PrV (Curtis and Kleinfeld, 2006).…”

Acute Thrombotic Infarction Suppresses Metabolic Activation of Ipsilateral Somatosensory Cortex: Evidence for Functional Diaschisis

“…Previous investigations employing focal electrical stimulation of MI have shown at least a partial func tional overlap between the lateral agranular field of MI and the granular cortex of the first somatosen-sory cortex (SI) (Donoghue and Wise, 1982;Hall and Lindholm, 1974). Corticocortical interconnec tions between MI and SI are suggested by a study in which electrical stimulation of the motor cortex sufficient to produce contralateral vibrissae move ment led to bilateral columnar increases in 2-deoxyglucose uptake in the SI (Sharp and Evans, 1982). The absence of increased 2-DG uptake in ventrobasal thalamus in that study suggests that the increased metabolic activity of SI was not mediated via specific thalamocortical projections.…”

Cholinergic Modulation of Vibrissal Receptive Fields in Trigeminal Nuclei

“…Collectively, PPTg cells are most active during states of electroencephalographic desynchronization, and there exists a number of findings linking ACh release from the PPTg to the electrophysiological and behavioral manifestations of REM sleep (for review, see McCarley, 2004). For the moment, we have very little insight into the role(s) of the SpVi in the vibrissal system, but there is metabolic evidence that this nucleus gets activated during selfgenerated whisker motion (Sharp and Evans, 1982;Jacquin et al, 1993). Considering the behavioral importance of information gathered through whisker motion in rodents (Welker, 1964), it is perhaps not surprising that subtle shifts in arousal level produce immediate vibrissa reactions and rapid excitability adjustments at the very first relay stations of this system.…”