Transient and long-lasting electrical responses to direct hippocampal stimulation

1960 ◽  
Vol 198 (4) ◽  
pp. 687-692 ◽  
Author(s):  
E. R. Kandel ◽  
W. A. Spencer ◽  
F. J. Brinley
Keyword(s):  
Output Curve ◽  
Input Output ◽  
Negative Wave ◽  
Typical Response ◽  
Test Response ◽  
Hippocampal Stimulation ◽  
Direct Cortical Response ◽  
Electrical Stimuli ◽  
Apical Dendrites

Widely accepted use of the direct cortical response (DCR) for the study of neocortical apical dendrites prompted this study of the response of the surface of hippocampal pallium to direct electrical stimuli in rabbits anesthetized with Dial or Evipal. The hippocampus was directly exposed by radical decortication. The most typical response to direct hippocampal stimulation (DHR) is a monophasic 20–25 msec. negative wave. The DHR is linearly graded throughout the early part of its input-output curve, shows no refractoriness, exhibits long lasting (400 msec.) potentiation of a previously conditioned test response, is rapidly (3–5 sec.) inverted by GABA and is associated with two types of d.c. shifts: a) d.c. shift without concomitant loss of the DHR and b) a variant of spreading hippocampal depression. From these properties the DHR would appear to be quite similar to the DCR. However, different bioelectric generators must be postulated since the hippocampal neural geometry is different from neocortex with respect to the orientation of its predominant neurons.

Optimization of Planar, Spherical and Spatial Function Generators Using Input-Output Curve Planning

1994 ◽  
Vol 116 (3) ◽  
pp. 915-919 ◽  
Author(s):  
Zheng Liu ◽  
J. Angeles
Keyword(s):  
Performance Index ◽  
General Scheme ◽  
Optimization Procedure ◽  
Output Curve ◽  
Input Output ◽  
Function Generation ◽  
Spatial Function ◽  
Function Generators ◽  
Design Requirements ◽  
A Performance

A general scheme for the optimization of planar, spherical and spatial bimodal linkages for function generation is proposed. The problem is solved here following two basic steps: (i) planning input-output ((I/O) curves based on design requirements and selecting data from the planned curve; and (ii) setting up an optimization procedure to minimize a performance index.

scholarly journals Eight weeks of local vibration training increases dorsiflexor muscle cortical voluntary activation

2017 ◽  
Vol 122 (6) ◽  
pp. 1504-1515 ◽  
Author(s):  
Robin Souron ◽  
Adrien Farabet ◽  
Léonard Féasson ◽  
Alain Belli ◽  
Guillaume Y. Millet ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Output Curve ◽  
Input Output ◽  
Local Vibration ◽  
Vibration Training

The aim of this study was to evaluate the effects of an 8-wk local vibration training (LVT) program on functional and corticospinal properties of dorsiflexor muscles. Forty-four young subjects were allocated to a training (VIB, n = 22) or control (CON, n = 22) group. The VIB group performed twenty-four 1-h sessions (3 sessions/wk) of 100-Hz vibration applied to the right tibialis anterior. Both legs were tested in each group before training (PRE), after 4 (MID) and 8 (POST) wk of training, and 2 wk after training (POST2W). Maximal voluntary contraction (MVC) torque was assessed, and transcranial magnetic stimulation (TMS) was used to evaluate cortical voluntary activation (VATMS), motor evoked potential (MEP), cortical silent period (CSP), and input-output curve parameters. MVC was significantly increased for VIB at MID for right and left legs [+7.4% ( P = 0.001) and +6.2% ( P < 0.01), respectively] and remained significantly greater than PRE at POST [+12.0% ( P < 0.001) and +10.1% ( P < 0.001), respectively]. VATMS was significantly increased for right and left legs at MID [+4.4% ( P < 0.01) and +4.7% ( P < 0.01), respectively] and at POST [+4.9% ( P = 0.001) and +6.2% ( P = 0.001), respectively]. These parameters remained enhanced in both legs at POST2W. MEP and CSP recorded during MVC and input-output curve parameters did not change at any time point for either leg. Despite no changes in excitability or inhibition being observed, LVT seems to be a promising method to improve strength through an increase of maximal voluntary activation, i.e., neural adaptations. Local vibration may thus be further considered for clinical or aging populations. NEW & NOTEWORTHY The effects of a local vibration training program on cortical voluntary activation measured with transcranial magnetic stimulation were assessed for the first time in dorsiflexors, a functionally important muscle group. We observed that training increased maximal voluntary strength likely because of the strong and repeated activation of Ia spindle afferents during vibration training that led to changes in the cortico-motoneuronal pathway, as demonstrated by the increase in cortical voluntary activation.

Comparison of direct cerebral and cerebellar cortical responses in the cat

1960 ◽  
Vol 199 (4) ◽  
pp. 677-682 ◽  
Author(s):  
Albert Rhoton ◽  
Sidney Goldring ◽  
James L. O'Leary
Keyword(s):  
Cerebral Cortex ◽  
Synaptic Activity ◽  
Aminobutyric Acid ◽  
Cortical Surface ◽  
Gamma Aminobutyric Acid ◽  
Positive Polarity ◽  
Negative Wave ◽  
Negative Spike ◽  
Cortical Responses ◽  
Direct Cortical Response

Surface-evoked cerebral and cerebellar responses were compared in 35 cats. Single stimuli and 1-second trains (6 and 20/sec.) were used. Effects of gamma aminobutyric acid (GAB) applied to the cortical surface and of Nembutal and procaine injected intravenously were studied. Response of cerebral cortex to a single shock shows at least four components: initial negative spike, second negative wave, after-positivity, and slow negativity. Cerebellum shows only the initial negative spike and the slow negativity, second negative and after-positivity components being absent. In both cerebrum and cerebellum slow negativity shows summation with serial stimulation. Application of GAB to the cerebellar surface causes replacement of the negative spike by a positive one and a concurrent reduction in amplitude of slow negativity. In cerebral cortex Nembutal produces a striking augmentation of singly or serially evoked slow negativity, but marked amplitude reduction or reversal to positive polarity of the serially evoked primary spikes. By contrast procaine abolishes summed slow negativity of cerebral cortex leaving serial spikes unaffected. In the cerebellum Nembutal and procaine have no effect upon the direct cortical response at dosage sufficient to produce cerebral alterations. Thus synaptic activity signaled by the responses studied appears to be more susceptible to Nembutal and procaine in cerebrum than in cerebellum.

scholarly journals Lognormal firing rate distribution reveals prominent fluctuation–driven regime in spinal motor networks

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Peter C Petersen ◽  
Rune W Berg
Keyword(s):  
Neuronal Population ◽  
Output Curve ◽  
Input Output ◽  
Rhythmic Movements ◽  
Trade Off ◽  
Firing Rates ◽  
Spinal Motor ◽  
Rich Diversity ◽  
The Mean ◽  
Lumbar Spinal

When spinal circuits generate rhythmic movements it is important that the neuronal activity remains within stable bounds to avoid saturation and to preserve responsiveness. Here, we simultaneously record from hundreds of neurons in lumbar spinal circuits of turtles and establish the neuronal fraction that operates within either a ‘mean-driven’ or a ‘fluctuation–driven’ regime. Fluctuation-driven neurons have a ‘supralinear’ input-output curve, which enhances sensitivity, whereas the mean-driven regime reduces sensitivity. We find a rich diversity of firing rates across the neuronal population as reflected in a lognormal distribution and demonstrate that half of the neurons spend at least 50 % of the time in the ‘fluctuation–driven’ regime regardless of behavior. Because of the disparity in input–output properties for these two regimes, this fraction may reflect a fine trade–off between stability and sensitivity in order to maintain flexibility across behaviors.

Electrophysiological mapping of GABAA receptor-mediated inhibition in adult rat somatosensory cortex

1996 ◽  
Vol 75 (4) ◽  
pp. 1589-1600 ◽  
Author(s):  
P. A. Salin ◽  
D. A. Prince
Keyword(s):  
Gabaa Receptor ◽  
Kinetic Properties ◽  
Output Curve ◽  
Horizontal Distance ◽  
Gamma Aminobutyric Acid ◽  
Input Output ◽  
Patch Clamp Technique ◽  
Horizontal Field ◽  
Layer V ◽  
Layer I

1. gamma-Aminobutyric acid-A (GABAA) receptor-mediated synaptic currents evoked by intracortical stimulation in rat somatosensory cortical slices maintained in vitro were studied using the whole cell patch-clamp technique. All anatomically identified pyramidal neurons of layer II-III (SG neurons), layer IV (IV neurons), and layer V (IG neurons) generated evoked inhibitory postsynaptic currents (eIPSCs) that were blocked by bicuculline. At threshold, eIPSCs had kinetic properties (rise time of 0.9 ms and decay time constant of 9 ms) similar to those of spontaneous IPSCs generated in the same cells. 2. The strength of inhibition was quantified by determining the stimulus threshold for evoking responses and the relationship between stimulus strength and eIPSC peak amplitudes (input/output curve). For eIPSCs recorded in control solution, the input/output curve was about four times steeper than for eIPSCs recorded in the presence of the ionotropic glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D-2-amino-5-phosphonovalerate (D-AP5), suggesting the dependence of GABAA inhibition on synpatic excitation of interneurons. 3. In the presence of CNQX and D-AP5, monosynaptic IPSCs, evoked by stimulation close to the recording patch pipette, had similar input/output curves in SG and IG neurons. This suggests that the level of monosynaptic inhibition generated in these two populations of cells is similar. 4. When the stimulus was moved to a distant site > 350 microns from the recorded neuron, either in vertical or in horizontal direction, the stimulus intensity required for evoking IPSCs was higher, and the input/output curve was less steep. This suggests that the density of GABAergic somata and axons projecting to the recorded neuron is lower at these distances than at more proximal sites. 5. The maximum horizontal distance over which IPSCs could be evoked ("horizontal field") was larger in layer V than in other layers. The horizontal field (distance between stimulating and recording pipettes) was 600 microns in layer II-III, 580 microns in layer IV, and 720 microns in layer V. Anatomic identification of the somatosensory cortical barrels indicated that the extent of GABAergic projections was larger than the barrel hollow and might thus form a substrate for interbarrel inhibition in layer IV during cross-wisker stimulation. 6. The maximum vertical inhibitory field was larger than the maximum horizontal field. IPSCs could be evoked in layer V neurons by layer I stimuli, showing that a powerful interlaminar inhibition is present that may play a role in synchronizing the activity of neurons in a column. IPSCs evoked by layer I stimulation frequently had slower kinetics than those elicited by stimulation at sites close to the soma. 7. These findings suggest that functional GABAergic projections are characterized by a large degree of convergence. Quantification of GABAA-mediated IPSCs indicates that this zone of inhibitory synaptic convergence onto a given pyramidal neuron is subdivided into a powerful local inhibitory zone and a surrounding area of long-range, less effective, inhibitory projections. Potential roles for these concentric inhibitory areas in cortical processing of sensory information are discussed.

Optimization of Function-Generating Mechanisms Using Input-Output Curve Planning: Part II — Formulation and Optimization Strategies

1992 ◽  
Author(s):  
Zheng Liu ◽  
Jorge Angeles
Keyword(s):  
Optimization Procedure ◽  
Second Step ◽  
Output Curve ◽  
Data Preparation ◽  
Input Output ◽  
Optimization Scheme ◽  
Design Data ◽  
Transmission Quality ◽  
Design Requirements ◽  
Defect Elimination

Abstract As a sequel to Part I, in which design-data preparation based on Input-output curve planning is discussed, Part II focuses on the second step of the optimization scheme. This step includes the basic formulation and some strategies, in the optimization procedure, for: i) transmission-quality evaluation; and ii) branch-defect elimination. Since design requirements on mobility conditions are already considered in the curve-planning phase, discussed in Part I, there is no need to introduce constraints pertaining to mobility type in the formulation, the procedure thus becoming remarkably simple.

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