scholarly journals Autonomic and respiratory components of orienting behaviors are mediated by descending pathways originating from the superior colliculus

2021 ◽  
Author(s):  
Erin Lynch ◽  
Bowen Richard Dempsey ◽  
Eloise Monteiro ◽  
Anita J Turner ◽  
Christine Saleeba ◽  
...  
Keyword(s):  
Superior Colliculus ◽  
Brain Function ◽  
Physiological Responses ◽  
Neural Pathways ◽  
Descending Pathways ◽  
Medullary Reticular Formation ◽  
Premotor Pathways ◽  
Descending Projections ◽  
Major Target ◽  
Stimulation Of

The ability to discriminate competing, ecologically relevant stimuli, and initiate contextually appropriate behaviors, is a key brain function. Neurons in the deep superior colliculus (dSC) integrate multisensory inputs and activate descending projections to premotor pathways responsible for orienting and attention, which often involve adjustments to respiratory and cardiovascular parameters. However, the neural pathways that subserve physiological components of orienting are poorly understood. We report that orienting responses to optogenetic dSC stimulation are accompanied by short-latency autonomic, respiratory and electroencephalographic effects in conscious rats, closely mimicking those evoked by naturalistic alerting stimuli. Physiological responses occurred in the absence of detectable aversion or fear and persisted under urethane anesthesia, indicating independence from emotional stress. Moreover, autonomic responses were replicated by selective stimulation of dSC inputs to the medullary reticular formation, a major target of dSC motor efferents, This disynaptic pathway represent a likely substrate for autonomic components of orienting.

Role of adrenal catecholamines in cerebrovasodilation evoked from brain stem

1987 ◽  
Vol 252 (6) ◽  
pp. H1183-H1191
Author(s):  
C. Iadecola ◽  
P. M. Lacombe ◽  
M. D. Underwood ◽  
T. Ishitsuka ◽  
D. J. Reis
Keyword(s):  
Brain Function ◽  
Blood Gases ◽  
Brain Regions ◽  
Elevated Plasma ◽  
Regional Cerebral Blood ◽  
Medullary Reticular Formation ◽  
Alpha Chloralose ◽  
The Brain ◽  
Stimulation Of

We studied whether adrenal medullary catecholamines (CAs) contribute to the metabolically linked increase in regional cerebral blood flow (rCBF) elicited by electrical stimulation of the dorsal medullary reticular formation (DMRF). Rats were anesthetized (alpha-chloralose, 30 mg/kg), paralyzed, and artificially ventilated. The DMRF was electrically stimulated with intermittent trains of pulses through microelectrodes stereotaxically implanted. Blood gases were controlled and, during stimulation, arterial pressure was maintained within the autoregulated range for rCBF. rCBF and blood-brain barrier (BBB) permeability were determined in homogenates of brain regions by using [14C]iodoantipyrine and alpha-aminoisobutyric acid (AIB), respectively, as tracers. Plasma CAs (epinephrine and norepinephrine) were measured radioenzymatically. DMRF stimulation increased rCBF throughout the brain (n = 5; P less than 0.01, analysis of variance) and elevated plasma CAs substantially (n = 4). Acute bilateral adrenalectomy abolished the increase in plasma epinephrine (n = 4), reduced the increases in flow (n = 6) in cerebral cortex (P less than 0.05), and abolished them elsewhere in brain (P greater than 0.05). Comparable effects on rCBF were obtained by selective adrenal demedullation (n = 7) or pretreatment with propranolol (1.5 mg/kg iv) (n = 5). DMRF stimulation did not increase the permeability of the BBB to AIB (n = 5). We conclude that the increases in rCBF elicited from the DMRF has two components, one dependent on, and the other independent of CAs. Since the BBB is impermeable to CAs and DMRF stimulation fails to open the BBB, the results suggest that DMRF stimulation allows, through a mechanism not yet determined, circulating CAs to act on brain and affect brain function.

Neural pathways involved in sacral neuromodulation of reflex bladder activity in cats

2013 ◽  
Vol 304 (6) ◽  
pp. F710-F717 ◽  
Author(s):  
Fan Zhang ◽  
Shouguo Zhao ◽  
Bing Shen ◽  
Jicheng Wang ◽  
Dwight E. Nelson ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Sacral Neuromodulation ◽  
Bladder Capacity ◽  
Inhibitory Effect ◽  
Ventral Root ◽  
Neural Pathways ◽  
Descending Pathways ◽  
The Central Nervous System ◽  
Bladder Activity ◽  
Stimulation Of

This study examined the mechanisms underlying the effects of sacral neuromodulation on reflex bladder activity in chloralose-anesthetized cats. Bladder activity was recorded during cystometrograms (CMGs) or under isovolumetric conditions. An S1–S3 dorsal (DRT) or ventral root (VRT) was electrically stimulated at a range of frequencies (1–30 Hz) and at intensities relative to threshold (0.25–2T) for evoking anal/toe twitches. Stimulation of DRTs but not VRTs at 1T intensity and frequencies of 1–30 Hz inhibited isovolumetric rhythmic bladder contractions. A 5-Hz DRT stimulation during CMGs was optimal for increasing ( P < 0.05) bladder capacity (BC), but stimulation at 15 and 30 Hz was ineffective. Stimulation of the S1 DRT was more effective (increases BC to 144% and 164% of control at 1T and 2T, respectively) than S2 DRT stimulation (increases BC to 132% and 150% of control). Bilateral transection of the hypogastric or pudendal nerves did not change the inhibitory effect induced by S1 DRT stimulation. Repeated stimulation of S1 and S2 DRTs during multiple CMGs elicited a significant ( P < 0.05) increase in BC (to 155 ± 11% of control) that persisted after termination of the stimulation. These results in cats suggest that the inhibition of reflex bladder activity by sacral neuromodulation occurs primarily in the central nervous system by inhibiting the ascending or descending pathways of the spinobulbospinal micturition reflex.

The laminar distribution of macaque tectobulbar and tectospinal neurons

1992 ◽  
Vol 8 (3) ◽  
pp. 257-276 ◽  
Author(s):  
Paul J. May ◽  
John D. Porter
Keyword(s):  
Spinal Cord ◽  
Superior Colliculus ◽  
Reticular Formation ◽  
Retrograde Transport ◽  
Physiological Data ◽  
Pontine Reticular Formation ◽  
Descending Pathways ◽  
Cells Of Origin ◽  
Descending Projections ◽  
The Brain

AbstractThe superior colliculus exerts its most direct influence over orienting movements, and saccades in particular, via its descending projections to the brain stem and spinal cord. However, while there is detailed physiological data concerning the generation of saccade-related activity in the primate superior colliculus, there is relatively little data on the detailed connectivity of this structure in primates. Consequently, retrograde transport techniques were utilized to determine the locations of the cells of origin of these descending pathways in macaque monkeys. Tectal cells that projected to the ipsilateral pontine reticular formation were mainly found in the deep gray layer and occasionally in the intermediate gray layer. Tectal cells that projected to the contralateral pontine reticular formation were predominantly located in the intermediate gray layer. The contralaterally projecting population could be subdivided into two groups. The cells in upper sublamina of the intermediate gray layer project primarily to the saccade-related regions of the paramedian reticular formation. Cells in the lower sublamina project primarily to more lateral regions of the pontine reticular formation and to the spinal cord. We conclude that the primate colliculus is provided with at least three descending output channels, which are likely to differ in their connections and functions. Specifically, it seems likely that the lower portion of the intermediate gray layer may be specialized to subserve combined head and eye orienting movements, while the upper sublamina subserves saccades.

Descending Auditory Pathways and Plasticity

2018 ◽  
pp. 610-638
Author(s):  
Brett R. Schofield ◽  
Nichole L. Beebe
Keyword(s):  
Auditory System ◽  
Superior Olivary Complex ◽  
Descending Pathways ◽  
Auditory Pathways ◽  
System P ◽  
Multiple Levels ◽  
Ventral Nucleus ◽  
Descending Projections ◽  
Trapezoid Body ◽  
Major Target

Descending auditory pathways originate from multiple levels of the auditory system and use a variety of neurotransmitters, including glutamate, GABA, glycine, acetylcholine, and dopamine. Targets of descending projections include cells that project to higher or lower centers, setting up circuit loops and chains that provide top-down modulation of many ascending and descending circuits in the auditory system. Descending pathways from the auditory cortex can evoke plasticity in subcortical centers. Such plasticity relies, at least in part, on brainstem cholinergic systems that are closely tied to descending cortical projections. Finally, the ventral nucleus of the trapezoid body, a component of the superior olivary complex, is a major target of descending projections from the cortex and midbrain. Through its complement of different neurotransmitter phenotypes, and its wide array of projections, the ventral nucleus of the trapezoid body is positioned to serve as a hub in the descending auditory system.

Cells of origin of medullary projections in central gray of rat mesencephalon

1980 ◽  
Vol 44 (5) ◽  
pp. 1002-1011 ◽  
Author(s):  
Y. Sakuma ◽  
D. W. Pfaff
Keyword(s):  
Female Rats ◽  
Spontaneous Discharge ◽  
Cerebral Aqueduct ◽  
Medullary Reticular Formation ◽  
Magnocellular Nuclei ◽  
Cells Of Origin ◽  
Central Gray ◽  
Descending Projections ◽  
Antidromic Response ◽  
Stimulation Of

1. Seventy-four neurons in the central gray of the mesencephalon were antidromically activated by electrical stimulation of the gigantocellular and magnocellular nuclei region of the ipsilateral medullary reticular formation in urethan-anesthetized female rats. An additional eight cells were located contralaterally. With control of the lordosis reflex (facilitated from central gray) in mind, each cell was characterized by the properties of its antidromic response and by its response to pressure stimulation of the hindquarters of the hindquarters of the animal. 2. The antidromically activated spikes had constant latencies between 1.0 and 25.5 ms, with a mean of 10.7 +/- 0.7 ms. 3. Cells of origin of the descending projections were located in all parts of the central gray and adjacent mesencephalic reticular field except within the inner ring of the central gray that surrounds the cerebral aqueduct. A particularly dense group of cells was noted in the ventrolateral aspect of the central gray. Fewer were found in the dorsal central gray over the cerebral aqueduct. 4. These cells had very low rates of spontaneous discharge or none at all. No specific changes in activity could be elicited by lordosis-relevant somatosensory stimuli. Therefore, these cells appear not to be involved in stimulus-bound reflexive control of lordosis behavior. Instead, they may be engaged in mediating influences descending from hypothalamus, known to control lordosis (see Ref. 48). In turn, they could modulate activity in reflex arcs completed at lower levels of the neuraxis.

scholarly journals Distinct fastigial output channels and their impact on temporal lobe seizures

2021 ◽  
Author(s):  
Martha L Streng ◽  
Madison R Tetzlaff ◽  
Esther Krook-Magnuson
Keyword(s):  
Superior Colliculus ◽  
Reticular Formation ◽  
Temporal Lobe ◽  
Seizure Control ◽  
Medullary Reticular Formation ◽  
Downstream Targets ◽  
Hippocampal Seizures ◽  
Lateral Nucleus ◽  
Stimulation Of ◽  
Seizure Suppression

Despite being canonically considered a motor control structure, the cerebellum is increasingly recognized for important roles in processes beyond this traditional framework, including seizure suppression. Excitatory fastigial neurons project to a large number of downstream targets, and it is unclear if this broad targeting underlies seizure suppression, or if a specific output may be sufficient. To address this question, we used the intrahippocampal kainic acid mouse model of temporal lobe epilepsy, male and female animals, and a dual-virus approach to selectively label and manipulate fastigial outputs. We examined fastigial neurons projecting to the superior colliculus, medullary reticular formation, and central lateral nucleus of the thalamus, and found that these comprise largely non-overlapping populations of neurons which send collaterals to unique sets of additional thalamic and brainstem regions, creating distinct, somewhat overlapping, output channels. We found that neither optogenetic stimulation of superior colliculus nor reticular formation output channels attenuated hippocampal seizures. In contrast, on-demand stimulation of fastigial neurons targeting the central lateral nucleus robustly inhibited seizures. Our results indicate that fastigial control of hippocampal seizures does not require simultaneous modulation of many fastigial output channels. Rather, selective modulation of the fastigial output channel to the central lateral thalamus, specifically, is sufficient for seizure control. This may provide a means for more selective therapeutic interventions, which provide seizure control while minimizing unwanted side effects. More broadly, our data highlight the concept of specific cerebellar output channels, whereby discrete cerebellar nucleus neurons project to specific aggregates of downstream targets, with distinct functional outcomes.

Supraspinal inhibition of a cutaneous vascular reflex in the cat

1964 ◽  
Vol 207 (2) ◽  
pp. 303-307 ◽  
Author(s):  
B. J. Prout ◽  
J. H. Coote ◽  
C. B. B. Downman
Keyword(s):  
Carotid Sinus ◽  
Spinal Reflexes ◽  
Descending Pathways ◽  
Skin Response ◽  
Reflex Arc ◽  
Vascular Reflex ◽  
Carotid Sinus Nerve Stimulation ◽  
Sympathetic Discharge ◽  
Stimulation Of ◽  
Cerebellar Stimulation

In cats anesthetized with chloralose-urethane mixture, stimulation of an afferent nerve evoked a vasoconstrictor reflex (VCR) and a galvanic skin response (GSR) in the pads of the feet. Stimulation of the ventromedial medullary reticular substance at the level of the obex abolished the VCR and the GSR. VCR could also be reduced by occlusion during prolonged stimulation of another spinal or visceral afferent pathway. Medulla stimulation was effective without itself causing a sympathetic discharge to the paw, showing that inhibition rather than occlusion was operative. Anterior cerebellar stimulation also inhibited the VCR. Carotid sinus nerve stimulation did not abolish the VCR. It is concluded that the effective mechanism includes a bulbospinal inhibitory path projecting on a spinal vasoconstrictor reflex arc. This arrangement is similar to the descending pathways inhibiting other spinal reflexes but the VCR-inhibitory path can be activated independently of them.

Effects of low-frequency stimulation of the superior colliculus on spontaneous and visually guided saccades

1993 ◽  
Vol 69 (3) ◽  
pp. 953-964 ◽  
Author(s):  
P. W. Glimcher ◽  
D. L. Sparks
Keyword(s):  
Superior Colliculus ◽  
Time Course ◽  
Low Frequency ◽  
Arbitrary Point ◽  
Visually Guided ◽  
Spontaneous Movements ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation ◽  
Stimulation Current ◽  
Stimulation Of

1. The first experiment of this study determined the effects of low-frequency stimulation of the monkey superior colliculus on spontaneous saccades in the dark. Stimulation trains, subthreshold for eliciting short-latency fixed-vector saccades, were highly effective at biasing the metrics (direction and amplitude) of spontaneous movements. During low-frequency stimulation, the distribution of saccade metrics was biased toward the direction and amplitude of movements induced by suprathreshold stimulation of the same collicular location. 2. Low-frequency stimulation biased the distribution of saccade metrics but did not initiate movements. The distribution of intervals between stimulation onset and the onset of the next saccade did not differ significantly from the distribution of intervals between an arbitrary point in time and the onset of the next saccade under unstimulated conditions. 3. Results of our second experiment indicate that low-frequency stimulation also influenced the metrics of visually guided saccades. The magnitude of the stimulation-induced bias increased as stimulation current or frequency was increased. 4. The time course of these effects was analyzed by terminating stimulation immediately before, during, or after visually guided saccades. Stimulation trains terminated at the onset of a movement were as effective as stimulation trains that continued throughout the movement. No effects were observed if stimulation ended 40–60 ms before the movement began. 5. These results show that low-frequency collicular stimulation can influence the direction and amplitude of spontaneous or visually guided saccades without initiating a movement. These data are compatible with the hypothesis that the collicular activity responsible for specifying the horizontal and vertical amplitude of a saccade differs from the type of collicular activity that initiates a saccade.

Effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure

1987 ◽  
Vol 66 (4) ◽  
pp. 548-554 ◽  
Author(s):  
Seigo Nagao ◽  
Tsukasa Nishiura ◽  
Hideyuki Kuyama ◽  
Masakazu Suga ◽  
Takenobu Murota
Keyword(s):  
Intracranial Pressure ◽  
Reticular Formation ◽  
Cerebral Blood Volume ◽  
Systemic Arterial Pressure ◽  
Brain Swelling ◽  
Dorsomedial Nucleus ◽  
Medullary Reticular Formation ◽  
Content Type ◽  
Fine Print ◽  
Stimulation Of

✓ The authors report the results of a study to evaluate the effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure (ICP) after the hypothalamic dorsomedial nucleus and midbrain reticular formation were destroyed. Systemic arterial pressure (BP), ICP, and local cerebral blood volume (CBV) were continuously recorded in 32 cats. To assess the changes in the cerebral vasomotor tonus, the vasomotor index defined by the increase in ICP per unit change in BP was calculated. In 29 of the 32 animals, BP, ICP, and CBV increased simultaneously immediately after stimulation. The increase in ICP was not secondary to the increase in BP, because the vasomotor index during stimulation was significantly higher than the vasomotor index after administration of angiotensin II. The vasomotor index was high during stimulation of the area around the nucleus reticularis parvocellularis. In animals with the spinal cord transected at the C-2 vertebral level, ICP increased without a change in BP. These findings indicate that the areas stimulated in the medullary reticular formation play an important role in decreasing cerebral vasomotor tonus. This effect was not influenced by bilateral superior cervical ganglionectomy, indicating that there is an intrinsic neural pathway that regulates cerebral vasomotor tonus directly. In three animals, marked biphasic or progressive increases in ICP up to 100 mm Hg were evoked by stimulation. The reduction of cerebral vasomotor tonus and concomitant vasopressor response induced by stimulation of the medullary reticular formation may be one of the causes of acute brain swelling.

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