Antidromic Response to Medullary Pyramid Stimulation inRats and Its Relation to That in Cats (Part 2 of 2)

1986 ◽  
Vol 29 (3-4) ◽  
pp. 153-161
Author(s):  
T.A. Harrison ◽  
A.L. Towe
Keyword(s):  
Medullary Pyramid ◽  
Antidromic Response

scholarly journals Timing of Impulses From the Central Amygdala and Bed Nucleus of the Stria Terminalis to the Brain Stem

2008 ◽  
Vol 100 (6) ◽  
pp. 3429-3436 ◽  
Author(s):  
Frank Z. Nagy ◽  
Denis Paré
Keyword(s):  
Brain Stem ◽  
Basolateral Amygdala ◽  
Stria Terminalis ◽  
Central Amygdala ◽  
Response Latencies ◽  
Bed Nucleus ◽  
Antidromic Responses ◽  
The Brain ◽  
Antidromic Response ◽  
Shed Light

The amygdala and bed nucleus of the stria terminalis (BNST) are thought to subserve distinct functions, with the former mediating rapid fear responses to discrete sensory cues and the latter longer “anxiety-like” states in response to diffuse environmental contingencies. However, these structures are reciprocally connected and their projection sites overlap extensively. To shed light on the significance of BNST–amygdala connections, we compared the antidromic response latencies of BNST and central amygdala (CE) neurons to brain stem stimulation. Whereas the frequency distribution of latencies was unimodal in BNST neurons (∼10-ms mode), that of CE neurons was bimodal (∼10- and ∼30-ms modes). However, after stria terminalis (ST) lesions, only short-latency antidromic responses were observed, suggesting that CE axons with long conduction times course through the ST. Compared with the direct route, the ST greatly lengthens the path of CE axons to the brain stem, an apparently disadvantageous arrangement. Because BNST and CE share major excitatory basolateral amygdala (BL) inputs, lengthening the path of CE axons might allow synchronization of BNST and CE impulses to brain stem when activated by BL. To test this, we applied electrical BL stimuli and compared orthodromic response latencies in CE and BNST neurons. The latency difference between CE and BNST neurons to BL stimuli approximated that seen between the antidromic responses of BNST cells and CE neurons with long conduction times. These results point to a hitherto unsuspected level of temporal coordination between the inputs and outputs of CE and BNST neurons, supporting the idea of shared functions.

Isolated infarction of medullary pyramid: Its clinical features and pathology

2013 ◽  
Vol 333 ◽  
pp. e220
Author(s):  
S. Kaji ◽  
H. Katada ◽  
S. Sato ◽  
H. Shibayama ◽  
T. Fukutake ◽  
...  
Keyword(s):  
Clinical Features ◽  
Medullary Pyramid

Somatotopic Arrangement of the Corticospinal Tract at the Medullary Pyramid in the Human Brain

2011 ◽  
Vol 65 (1) ◽  
pp. 46-49 ◽  
Author(s):  
Hyeok Gyu Kwon ◽  
Ji Heon Hong ◽  
Mi Young Lee ◽  
Yong Hyun Kwon ◽  
Sung Ho Jang
Keyword(s):  
Human Brain ◽  
Corticospinal Tract ◽  
Medullary Pyramid

scholarly journals Uniform Range of Conduction Times From the Lateral Amygdala to Distributed Perirhinal Sites

2002 ◽  
Vol 87 (3) ◽  
pp. 1213-1221 ◽  
Author(s):  
J. Guillaume Pelletier ◽  
Denis Paré
Keyword(s):  
Response Latency ◽  
Declarative Memory ◽  
Time Windows ◽  
Activity Patterns ◽  
Critical Role ◽  
Memory Storage ◽  
Response Latencies ◽  
Lateral Amygdala ◽  
Electrical Stimuli ◽  
Antidromic Response

Much data indicate that the perirhinal (PRH) cortex plays a critical role in declarative memory and that the amygdala facilitates this process under emotionally arousing conditions. However, assuming that the amygdala does so by promoting Hebbian interactions in the PRH cortex is hard to reconcile with the fact that variable distances separate amygdala neurons from their PRH projection sites. Indeed, to achieve a synchronized activation of distributed PRH sites, amygdala axons should display a uniform range of conduction times, irrespective of distance to target. To determine if amygdala axons meet this condition, we measured the antidromic response latencies of lateral amygdala (LA) neurons to electrical stimuli delivered at various rostrocaudal levels of the PRH cortex in cats anesthetized with isoflurane. Although large variations in antidromic response latencies were observed, they were unrelated to the distance between the PRH stimulation sites and LA neurons. To determine whether this result was an artifact due to current spread, two control experiments were performed. First, we examined the antidromic response latency of intrinsic PRH neurons. Although we used the same methods as in the first experiment, the antidromic response latency of PRH neurons to electrical stimuli applied in the PRH cortex increased linearly with the distance between the stimulating and recording sites. Second, we measured the antidromic response latency of PRH neurons projecting to the LA. In this pathway, we also found a statistically significant correlation between conduction times and distance to target. Thus these results support the intriguing possibility that the conduction velocity and/or trajectory of LA axons are adjusted to compensate for variations in distance between the LA and distinct rostrocaudal PRH sites. We hypothesize that because of their uniform range of conduction times to the PRH cortex, LA neurons can generate short time windows of depolarization facilitating Hebbian associations between coincident, but spatially distributed, activity patterns in the PRH cortex. In this context, the temporal scatter of conduction times in the LA to PRH pathway is conceived as a mechanism used to lengthen the period of depolarization to compensate for conduction delays within intrinsic PRH pathways. In part, this mechanism might explain how the amygdala promotes memory storage in emotionally arousing conditions.

An Intracellular Study of the Actions of Carbon Dioxide on the Spinal Monosynaptic Pathway

1973 ◽  
Vol 51 (6) ◽  
pp. 424-436 ◽  
Author(s):  
D. W. Esplin ◽  
R. Čapek ◽  
Barbara A. Esplin
Keyword(s):  
Transmitter Release ◽  
Afferent Fiber ◽  
Membrane Resistance ◽  
Postsynaptic Membrane ◽  
Release Mechanism ◽  
Afferent Fibers ◽  
Depressant Action ◽  
Intracellular Study ◽  
Primary Afferent Fibers ◽  
Antidromic Response

The actions of CO2 were studied on 48 lumbosacral motoneurones impaled with microelectrodes in spinal cats. CO2 produced a reversible depolarization in some cells tested and a reversible hyper-polarization in other cells tested. Both increases and decreases in membrane resistance were produced by CO2, and these were significantly correlated with hyperpolarizations and depolarizations of the membrane, respectively. The after-hyperpolarization following an antidromic response was always reduced by CO2, irrespective of the CO2-induced change in membrane potential. The firing threshold of the motoneurone in response to injected depolarizing currents was increased by CO2. Statistical analysis of excitatory postsynaptic potentials produced by activity in a single afferent fiber revealed that the principal depressant action of CO2 on this pathway is to block intraspinal branches of the primary afferent fibers. Neither the transmitter release mechanism nor the sensitivity of the postsynaptic membrane to the released transmitter was significantly affected.

scholarly journals Functional territories in primate substantia nigra pars reticulata separately signaling stable and flexible values

2015 ◽  
Vol 113 (6) ◽  
pp. 1681-1696 ◽  
Author(s):  
Masaharu Yasuda ◽  
Okihide Hikosaka
Keyword(s):  
Electrical Stimulation ◽  
Basal Ganglia ◽  
Substantia Nigra ◽  
Signal Transmission ◽  
Inhibitory Response ◽  
Substantia Nigra Pars Reticulata ◽  
Visual Objects ◽  
Direct Input ◽  
Antidromic Response ◽  
Stimulation Of

Gaze is strongly attracted to visual objects that have been associated with rewards. Key to this function is a basal ganglia circuit originating from the caudate nucleus (CD), mediated by the substantia nigra pars reticulata (SNr), and aiming at the superior colliculus (SC). Notably, subregions of CD encode values of visual objects differently: stably by CD tail [CD(T)] vs. flexibly by CD head [CD(H)]. Are the stable and flexible value signals processed separately throughout the CD-SNr-SC circuit? To answer this question, we identified SNr neurons by their inputs from CD and outputs to SC and examined their sensitivity to object values. The direct input from CD was identified by SNr neuron's inhibitory response to electrical stimulation of CD. We found that SNr neurons were separated into two groups: 1) neurons inhibited by CD(T) stimulation, located in the caudal-dorsal-lateral SNr (cdlSNr), and 2) neurons inhibited by CD(H) stimulation, located in the rostral-ventral-medial SNr (rvmSNr). Most of CD(T)-recipient SNr neurons encoded stable values, whereas CD(H)-recipient SNr neurons tended to encode flexible values. The output to SC was identified by SNr neuron's antidromic response to SC stimulation. Among the antidromically activated neurons, many encoded only stable values, while some encoded only flexible values. These results suggest that CD(T)-cdlSNr-SC circuit and CD(H)-rvmSNr-SC circuit transmit stable and flexible value signals, largely separately, to SC. The speed of signal transmission was faster through CD(T)-cdlSNr-SC circuit than through CD(H)-rvmSNr-SC circuit, which may reflect automatic and controlled gaze orienting guided by these circuits.

scholarly journals Medulla of kidney – A Postmortem Grossmorphological Study in Bangladeshi People

2014 ◽  
Vol 13 (2) ◽  
pp. 155-157
Author(s):  
SM Nurul Hassan ◽  
Habibur Rahaman ◽  
Mansur Khalil ◽  
Mohsin Khalil
Keyword(s):  
Kidney Diseases ◽  
Medical Science ◽  
Age Groups ◽  
Renal Medulla ◽  
Cross Sectional ◽  
Medical College ◽  
Age Related ◽  
Study Type ◽  
Medullary Pyramid ◽  
Day By Day

Background: In Bangladesh, prevalence of kidney diseases is increasing day by day and it was observed that renal medulla is affected less in earlier period of life but in late period it becomes affected more. Moreover renal mass changes with age which affecting the medullary mass and consequently the number of medullary pyramids. So the present study was carried out to evaluate anatomical features of medulla and to count the medullary pyramids with age related changes in the number of the pyramids in Bangladeshi people. Study type: Cross sectional analytical type of study. Place and period of study: Department of Anatomy, Mymensingh Medical College, Mymensingh, Bangladesh from January 2004 to June 2005. Materials and methods: A total of 70 fresh human kidneys of both sexes and sides were collected from the morgue of Mymensingh Medical College at postmortem. The selected cases were between 5 to 60 years of age. The samples were divided into 3 different age groups (A: 05-15 years, B: 16-35 years, C: 36- 60 years) to observe the variations in number of medullary pyramid of kidney in different age groups. Results: Among three groups, highly significant (<0.001) differences were found statistically in the number of medullary pyramid. Conclusion: There were changes in the number of medullary pyramid of kidney in different age groups. DOI: http://dx.doi.org/10.3329/bjms.v13i2.18299 Bangladesh Journal of Medical Science Vol.13(2) 2014 p.155-157

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