The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

1984 ◽  
Vol 221 (1224) ◽  
pp. 261-289 ◽  
Keyword(s):  
Intracellular Recording ◽  
Brain Function ◽  
Tonic Inhibition ◽  
Resting Potential ◽  
Inhibitory Pathway ◽  
Plantaris Tendon ◽  
Hindlimb Muscles ◽  
Or Groups ◽  
Motor Nuclei ◽  
Knee Flexors

The pattern of la-connections to motor nuclei of 17 hindlimb muscles (or groups of muscles) has been investigated in baboons by intracellular recording of Ia-e.ps.p.s evoked in motoneurons from different muscle nerves. The amplitudes are normalized to 70 mV resting potential and compared with similarly normalized Ia-e.ps.p.s in cats. As in the cat, la-excitation is drawn from a restricted number of muscles and the homonymous effect is usually dominating. Heteronymous connections to many motor nuclei are different in the two species. For example, hip extensors are generally more la-isolated from each other in baboons than in cats, and also knee flexors have fewer Iainterconnections than in cats. A unidirectional Ia-synergism between some hip extensors and knee flexors in cats has changed to a bidirectional one in baboons, with a tendency to lateralization of the connections. Among ankle extensors, soleus has smaller heteronymous I a-connections from its synergic ankle extensors than in cats. In baboons, plantaris is heteronymously I a-excited from gastrocnemius-soleus but not from the intrinsic plantar muscles; whereas in cats there exists a considerable la-projection from the intrinsic plantar muscles but not from gastrocnemius-soleus. There is a corresponding difference in the insertion of the plantaris tendon, which shows that this muscle acts as toe extensor in cats but as ankle extensor in baboons. For most of the motor nuclei, the homonymous as well as the total aggregate of Ia-e.ps.p.s is smaller in the baboon than in the cat; but the amplitude range between different motor nuclei is larger in the baboon. Reciprocal Ia-i.ps.p.s are evoked only after spinal transection or when brain function is depressed. It is postulated that baboons, contrary to cats, have descending tonic inhibition of transmission in the reciprocal la-inhibitory pathway. The phylogenetic flexibility of I a-connections is discussed and contrasted with their ontogenetic stability.

scholarly journals Ionic dependence of secretory and electrical activity evoked by elevated K+ in a peptidergic neurosecretory system

1984 ◽  
Vol 113 (1) ◽  
pp. 289-321 ◽  
Author(s):  
I. M. Cooke ◽  
B. A. Haylett
Keyword(s):  
Electrical Activity ◽  
Normal Saline ◽  
Intracellular Recording ◽  
Resting Potential ◽  
Neurosecretory System ◽  
Repetitive Firing ◽  
Inward Current ◽  
Dependent Inactivation ◽  
High K ◽  
Net Uptake

Secretion of the octapeptide erythrophore- (red pigment-) concentrating hormone (ECH, RPCH) and extracellularly monitored electrical activity were followed simultaneously from individual, isolated sinus glands (neurohaemal organs), of the crab Cardisoma carnifex. Following introduction of saline having elevated [K], 100–196 mmol l-1 (5–11 X normal), secretion (bioassayed from 1-min fractions during continuous perfusion) increases from barely detectable (less than 1 fmol min-1) to a peak, average 31 fmol min-1, within 5 min, and immediately subsides. Additional responses are obtainable following a period, greater than 30 min, of normal saline perfusion. Secretory responses to K are Ca-dependent. If Ca is restored (in high K) following perfusion in 0-Ca, high K, only a small secretory response is observed. Addition of Mn (10 mmol l-1, normal Ca) reduces secretion to one-tenth. Increased net uptake of 45Ca of 2.5- to 6-fold is observed in individual sinus glands exposed to 10 X K compared to paired, unstimulated organs. The pattern and Ca-dependence of secretory responses to K are unaffected, but the amount of secretion is augmented in Na-deficient or TTX-containing salines. Intracellular recording confirms that brief (10–40 s) bouts of intense firing recorded extracellularly upon commencing a high K perfusion include repetitive firing by terminals, superimposed on rapid depolarization. Firing ceases as the membrane potential reaches a depolarized value (−18 to −15 mV for [K] 100–176 mmol l-1), which is then maintained until restoration of normal saline, when slow repolarization ensues. In 0-Ca, spontaneous impulse firing is increased, resting potential depolarized by 5 to 15 mV, but the bout of impulse firing and the maintained depolarization in response to K are similar. Thus, mechanisms of secretion of a crustacean peptide neurohormone appear closely similar to those of other systems characterized: responsiveness to elevated K, dependence on Ca, depolarization-, but not secretion-dependent inactivation, and lack of dependence on Na inward current. Intracellular recording here permits direct observation of electrical responses of terminals.

scholarly journals Inside Information: Systematic within-node connectivity changes observed across tasks or groups

2021 ◽  
Author(s):  
Wenjing Luo ◽  
Robert T Constable
Keyword(s):  
Brain Function ◽  
Inside Information ◽  
Substantial Fraction ◽  
Connectivity Information ◽  
Or Groups ◽  
Node Connectivity ◽  
Clinical Potential

Mapping the human connectome and understanding its relationship to brain function holds tremendous clinical potential. The connectome has two fundamental components: the nodes and the connections between them. While much attention has been given to deriving atlases and measuring the connections between nodes, there have been no studies examining the networks within nodes. Here we demonstrate that each node contains significant connectivity information, that varies systematically across task-induced states and subjects, such that measures based on these variations can be used to classify tasks and identify subjects. The results are not specific for any particular atlas but hold across different atlas resolutions. To date, studies examining changes in connectivity have focused on edge changes and assumed there is no useful information within nodes. Our findings illustrate that for typical atlases, within-node changes can be significant and may account for a substantial fraction of the variance currently attributed to edge changes.

Chloride self-exchange in toad skeletal muscle in vivo and in vitro

1982 ◽  
Vol 242 (3) ◽  
pp. C207-C217 ◽  
Author(s):  
D. D. Macchia
Keyword(s):  
Muscle Cells ◽  
Ringer Solution ◽  
Resting Potential ◽  
Electrochemical Gradient ◽  
Hindlimb Muscles ◽  
A Value ◽  
Hindlimb Muscle ◽  
The Mean

The exchange of cellular Cl with 36Cl has been measured in saline-perfused hindlimb muscles of the pithed toad and compared with cellular Cl exchange in isolated muscles incubated in the vitro either in toad Ringer solution or in toad plasma. In the perfused hindlimb, the rate of 36Cl efflux from muscle cells [17.0 +/- 0.9 pmol Cl.(cm2 plasma membrane.s)-1] was only 40% as fast as that of the 36Cl influx. The discrepancy between Cl influx and efflux was accompanied by a cellular accumulation of Cl against the electrochemical gradient for this anion. Concurrently, the cells took up Na in amounts at least equal to the accumulated Cl. During this accumulation of Na and Cl, the mean resting potential remained constant at a value of -89.2 +/- 1.9 (SE) mV. Na and Cl were taken up by the muscle cells of the perfused hindlimb without a concomitant decrease in cellular K content; i.e., without evidence of inhibition of the Na-K pump. The rate constant for cellular 36Cl efflux from isolated toad muscles preincubated for 3 h in vitro in toad Ringer solution was about five times faster than that of muscles in the perfused hindlimb and similar in magnitude to published values for Cl fluxes in frog muscle. Cellular Cl efflux from muscles briefly preincubated in vitro for 15 min instead of 3 h was significantly slower than after prolonged preincubation. In vitro incubation of isolated toad muscles in toad plasma slowed the cellular 36Cl efflux to values approaching those measured in the perfused hindlimb, without comparably depressing the 36Cl influx. It is suggested that the uptake of NaCl by the cells of perfused hindlimb muscle may proceed by an electroneutral inward cotransport of Na and Cl on the same carrier.

scholarly journals Slow and Fast Responses in Cockroach Leg Muscle

1954 ◽  
Vol 31 (2) ◽  
pp. 280-290
Author(s):  
V. J. WILSON
Keyword(s):  
Intracellular Recording ◽  
Motor Units ◽  
Fast Response ◽  
Resting Potential ◽  
Extracellular Potassium ◽  
Muscle Fibres ◽  
Slow Fibre ◽  
Fast System ◽  
Fast Fibre ◽  
Frequency Of Stimulation

1. Intracellular recording from individual muscle fibres of the flexor tibiae of the cockroach shows two types of action potentials. One of these represents fast fibre activity, while the other represents slow fibre activity in this muscle. 2. The fast response consists of an all-or-none potential varying from 40 to 85 mV., with 6o% of the responses between 55 and 70 mV. This potential has an overshoot over the resting potential, and is followed by an absolute and a relative refractory period. For these reasons it is considered likely that the potential is a propagated one. The slow response is a small, facilitating potential, varying from 8 to 20 mV., and is quite likely a local phenomenon. 3. All the evidence indicates that the two types of activity do not take place in the same muscle fibres, but rather represent the responses of two different types of fibres, as is the case in some amphibian muscles. 4. Gradation of activity in the fast system seems to depend solely on the activation of a very small number of motor units and on mechanical summation. The response of this system shows little, if any, facilitation as the frequency of stimulation is increased. The facilitating slow system may be concerned with slower, more finely graded movements. 5. The resting potential in roach muscle has an amplitude of 45 ±9 mV., which falls within the range expected on the basis of the intracellular and extracellular potassium concentrations. 6. Slow and fast fibre activity in insects and Crustacea is discussed, and a revision of the earlier work on Crustacea with the use of intracellular recording is suggested.

A challenge for predictive coding: Representational or experiential diversity?

2020 ◽  
Vol 43 ◽  
Author(s):  
Martina G. Vilas ◽  
Lucia Melloni
Keyword(s):  
Brain Function ◽  
Predictive Coding ◽  
Predictive Processing ◽  
Process Theory

Abstract To become a unifying theory of brain function, predictive processing (PP) must accommodate its rich representational diversity. Gilead et al. claim such diversity requires a multi-process theory, and thus is out of reach for PP, which postulates a universal canonical computation. We contend this argument and instead propose that PP fails to account for the experiential level of representations.

Toward a neuroscope: An application of high-performance computing for real-time evaluation of brain function using MRI

1994 ◽  
Vol 52 ◽  
pp. 922-923
Author(s):  
C. S. Potter ◽  
C. D. Gregory ◽  
H. D. Morris ◽  
Z.-P. Liang ◽  
P. C. Lauterbur
Keyword(s):  
Human Brain ◽  
Brain Function ◽  
High Performance ◽  
Complex Signal ◽  
Time Step ◽  
Brain Organization ◽  
Cognitive Studies ◽  
Positron Emission ◽  
Imaging And Spectroscopy ◽  
3D Anatomy

Over the past few years, several laboratories have demonstrated that changes in local neuronal activity associated with human brain function can be detected by magnetic resonance imaging and spectroscopy. Using these methods, the effects of sensory and motor stimulation have been observed and cognitive studies have begun. These new methods promise to make possible even more rapid and extensive studies of brain organization and responses than those now in use, such as positron emission tomography.Human brain studies are enormously complex. Signal changes on the order of a few percent must be detected against the background of the complex 3D anatomy of the human brain. Today, most functional MR experiments are performed using several 2D slice images acquired at each time step or stimulation condition of the experimental protocol. It is generally believed that true 3D experiments must be performed for many cognitive experiments. To provide adequate resolution, this requires that data must be acquired faster and/or more efficiently to support 3D functional analysis.

Monitor Brain Function Selectively

2005 ◽  
Vol 38 (24) ◽  
pp. 18
Author(s):  
MARY ELLEN SCHNEIDER
Keyword(s):  
Brain Function

The Psychophysiology of Anxiety and Mood Disorders

2017 ◽  
Vol 225 (3) ◽  
pp. 175-188 ◽  
Author(s):  
Peter J. Lang ◽  
Lisa M. McTeague ◽  
Margaret M. Bradley
Keyword(s):  
Mental Health ◽  
Heart Rate ◽  
Brain Function ◽  
Physiological Reactivity ◽  
Research Domain Criteria ◽  
Diagnostic Systems ◽  
Psychophysiological Reactivity ◽  
Diagnostic Categories ◽  
New Research ◽  
Research Domain

Abstract. Several decades of research are reviewed, assessing patterns of psychophysiological reactivity in anxiety patients responding to a fear/threat imagery challenge. Findings show substantive differences in these measures within principal diagnostic categories, questioning the reliability and categorical specificity of current diagnostic systems. Following a new research framework (US National Institute of Mental Health [NIMH], Research Domain Criteria [RDoC]; Cuthbert & Insel, 2013 ), dimensional patterns of physiological reactivity are explored in a large sample of anxiety and mood disorder patients. Patients’ responses (e.g., startle reflex, heart rate) during fear/threat imagery varied significantly with higher questionnaire measured “negative affect,” stress history, and overall life dysfunction – bio-marking disorder groups, independent of Diagnostic and Statistical Manuals (DSM). The review concludes with a description of new research, currently underway, exploring brain function indices (structure activation, circuit connectivity) as potential biological classifiers (collectively with the reflex physiology) of anxiety and mood pathology.

Sign in / Sign up

Export Citation Format

Share Document