The effect of lesions of cerebellar cortex on retention of the classically conditioned eyeblink response when stimulation of the lateral reticular nucleus is used as the conditioned stimulus

The effect of electrical stimulation of the caudolateral brain stem on plasma adrenocorticotropin (ACTH) was assessed in cats anesthetized with alpha-chloralose-urethan. To examine the influence of stimulus pattern on ACTH release, an equal number of pulses was presented in a continuous pattern and in a burst pattern at each electrode site. Stimulation of the magnocellular portion (layers 4-6) of trigeminal nucleus caudalis evoked a significant (P less than 0.01) and equal peak change in plasma ACTH after continuous pattern (+121 +/- 32 pg/ml) and after burst pattern stimuli (+126 +/- 30 pg/ml, n = 21). In contrast, stimulation of more ventromedial portions (layers 7-8) of nucleus caudalis had no significant effect on plasma ACTH. Stimulation of the trigeminal lateral cervical region the caudal extent of the A1 noradrenergic cell group, or the lateral reticular nucleus evoked significant peak increases in plasma ACTH regardless of stimulus pattern. Transient changes in arterial pressure accompanied brain stem stimulation and were not correlated with the changes in ACTH. The results indicate that stimulation of trigeminal subnucleus caudalis, a brain stem region that processes nociceptor afferent information, evokes a prompt increase in plasma ACTH. Stimulation of brain stem regions that process autonomic and cardiovascular afferent information (A1 region, lateral reticular nucleus) also facilitate ACTH release. No significant influence of stimulus pattern on brain stem-evoked ACTH release was seen. The results support the hypothesis that the influence of the central nervous system on ACTH release may be processed by parallel pathways at the caudal brain stem level.

Download Full-text

Renal and somatic input to spinal neurons antidromically activated from the ventrolateral medulla

Journal of Neurophysiology ◽

10.1152/jn.1988.60.6.1967 ◽

1988 ◽

Vol 60 (6) ◽

pp. 1967-1981 ◽

Cited By ~ 14

Author(s):

W. S. Ammons

Keyword(s):

Reticular Formation ◽

Receptive Fields ◽

Ventrolateral Medulla ◽

Reticular Nucleus ◽

Lateral Reticular Nucleus ◽

Spinal Neurons ◽

C Fiber ◽

Somatic Input ◽

Fiber Stimulation ◽

Stimulation Of

1. Studies were done to characterize responses of spinal neurons backfired from the ventrolateral medulla to renal and somatic stimuli. Experiments were performed on 31 cats that were anesthetized with alpha-chloralose. Sixty-six spinal neurons were antidromically activated from the area of the lateral reticular nucleus or the ventrolateral reticular formation just rostral to the lateral reticular nucleus contralateral to the recording site. These cells could not be backfired from the medial reticular formation or from the spinothalamic tract just caudal to the thalamus. 2. Cells were located in laminae I, V, and VII of the T12-L2 segments. Antidromic conduction velocities averaged 35.9 +/- 7.2 m/s. Conduction velocities were unrelated to the projection site or laminar location of the cells. Termination sites of 21 cells were located in antidromic mapping experiments. Terminals were localized to the ventrolateral reticular formation, including the lateral reticular nucleus. 3. Responses to electrical stimulation of the renal nerves were always excitatory. Stimulation of renal A-delta-fibers excited 33 cells. These cells failed to respond to stimulation of renal C-fibers. The other 33 cells responded to both A-delta- and C-fiber stimulation. Latencies to A-delta-fiber stimulation averaged 9 +/- 2 ms, whereas latencies to C-fiber stimulation averaged 57 +/- 10 ms. 4. Renal mechanoreceptors were activated by occlusion of the renal vein or upper portion of the ureter. Renal vein occlusion excited 14 of 32 cells tested. Activity increased from 6 +/- 2 to 14 +/- 4 spike/s. Ureteral occlusion increased activity of 19 of 32 cells from 7 +/- 2 to 16 +/- 5 spikes/s. Cells responding to one of the mechanical stimuli were significantly more likely to receive A-delta-and C-fiber input compared with nonresponding cells. Nonresponders were more likely than responders to receive only A-delta input. 5. All cells received somatic input in addition to renal input. Twelve cells were classified as wide dynamic range, 46 as high threshold, and 8 as Deep. Somatic receptive fields most often included skin and muscle of the left flank and abdomen. Thirty-two cells had bilateral receptive fields, and 22 had inhibitory fields in addition to excitatory fields. 6. These data show that spinal neurons projecting to the ventrolateral medulla receive convergent inputs from the kidney and somatic structures. These cells may participate in a variety of functions including autonomic reflexes of renal origin.

Download Full-text