scholarly journals INFLUENCE OF RAT CENTRAL THALAMIC NEURONS ON FORAGING BEHAVIOR IN A HAZARDOUS ENVIRONMENT

2022 ◽  
Author(s):  
Mohammad Herzallah ◽  
Alon Amir ◽  
Denis Pare
Keyword(s):  
Foraging Behavior ◽  
Generalized Linear Model ◽  
Basolateral Amygdala ◽  
Thalamic Nucleus ◽  
Relative Magnitude ◽  
Firing Rates ◽  
Discharge Rates ◽  
Defensive Behaviors ◽  
Fast Spiking ◽  
Foraging Task

The basolateral amygdala (BL) is a major regulator of foraging behavior. Following BL inactivation, rats become indifferent to predators. However, at odds with the view that the amygdala detects threats and generate defensive behaviors, most BL neurons have reduced firing rates during foraging and at proximity of the predator. In search of the signals determining this unexpected activity pattern, this study considered the contribution of the central medial thalamic nucleus (CMT), which sends a strong projection to BL, mostly targeting its principal neurons. Inactivation of CMT or BL with muscimol abolished the rats’ normally cautious behavior in the foraging task. Moreover, unit recordings revealed that CMT neurons showed large but heterogeneous activity changes during the foraging task, with many neurons decreasing or increasing their discharge rates, with a modest bias for the latter. A generalized linear model revealed that CMT neurons encode many of the same task variables as principal BL cells. However, the nature (inhibitory vs. excitatory) and relative magnitude of the activity modulations seen in CMT neurons differed markedly from those of principal BL cells but were very similar to those of fast-spiking BL interneurons. Together, these findings suggest that, during the foraging task, CMT inputs fire some principal BL neurons, recruiting feedback interneurons in BL, resulting in the widespread inhibition of principal BL cells.

scholarly journals Basolateral amygdala neurons are activated during threat expectation

2019 ◽  
Vol 121 (5) ◽  
pp. 1761-1777 ◽  
Author(s):  
Alon Amir ◽  
Pinelopi Kyriazi ◽  
Seung-Chan Lee ◽  
Drew B. Headley ◽  
Denis Paré
Keyword(s):  
Brain Stem ◽  
Fear Conditioning ◽  
Linear Model ◽  
Unit Activity ◽  
Generalized Linear Model ◽  
Basolateral Amygdala ◽  
Unit Recording ◽  
Lateral Amygdala ◽  
Defensive Behaviors ◽  
Foraging Task

Fear conditioning studies have led to the view that the amygdala contains neurons that signal threat and in turn elicit defensive behaviors through their brain stem and hypothalamic targets. In agreement with this model, a prior unit-recording study in rats performing a seminaturalistic foraging task revealed that many lateral amygdala (LA) neurons are predator responsive. In contrast, our previous study emphasized that most basolateral (BL) amygdala neurons are inhibited at proximity of the predator. However, the two studies used different methods to analyze unit activity, complicating comparisons between them. By applying the same method to the sample of BL neurons we recorded previously, the present study revealed that most principal cells are inhibited by the predator and only 4.5% are activated. Moreover, two-thirds of these cells were also activated by nonthreatening stimuli. In fact, fitting unit activity with a generalized linear model revealed that the only task variables associated with a prevalent positive modulation of BL activity were expectation of the predator’s presence and whether the prior trial had been a failure or success. At odds with the threat-coding model of the amygdala, actual confrontation with the predator was usually associated with a widespread inhibition of principal BL neurons. NEW & NOTEWORTHY The basolateral amygdala (BL) is thought to contain neurons that signal threat, in turn eliciting defensive behaviors. In contrast, the present study reports that very few principal BL cells are responsive to threats and that most of them are also activated by nonthreatening stimuli. Yet, expectation of the threat’s presence was associated with a prevalent positive modulation of BL activity; actual confrontation with the threat was associated with a widespread inhibition.

Identification of Basolateral Amygdala Projection Cells and Interneurons Using Extracellular Recordings

2006 ◽  
Vol 96 (6) ◽  
pp. 3257-3265 ◽  
Author(s):  
Ekaterina Likhtik ◽  
Joe Guillaume Pelletier ◽  
Andrei T. Popescu ◽  
Denis Paré
Keyword(s):  
Firing Rate ◽  
Basolateral Amygdala ◽  
Cell Group ◽  
Small Subset ◽  
Cortical Projection ◽  
Antidromic Activation ◽  
Extracellular Recordings ◽  
Firing Rates ◽  
Cell Groups ◽  
Exact Position

This study tested whether firing rate and spike shape could be used to distinguish projection cells from interneurons in extracellular recordings of basolateral amygdala (BLA) neurons. To this end, we recorded BLA neurons in isoflurane-anesthetized animals with tungsten microelectrodes. Projection cells were identified by antidromic activation from cortical projection sites of the BLA. Although most projection cells fired spontaneously at low rates (<1 Hz), an important subset fired at higher rates (up to 6.8 Hz). In fact, the distribution of firing rates in projection cells and unidentified BLA neurons overlapped extensively, even though the latter cell group presumably contains a higher proportion of interneurons. The only difference between the two distributions was a small subset (5.1%) of unidentified neurons with unusually high firing rates (9–16 Hz). Similarly, distributions of spike durations in both cell groups were indistinguishable, although most of the fast-firing neurons had spike durations at the low end of the distribution. However, we observed that spike durations depended on the exact position of the electrode with respect to the recorded cell, varying by as much as 0.7 ms. Thus neither firing rate nor spike waveform allowed for unequivocal separation of projection cells from interneurons. Nevertheless, we propose the use of two firing rate cutoffs to obtain relatively pure samples of projection cells and interneurons: ≤1 Hz for projection cells and ≥7 Hz for fast-spiking interneurons. Supplemented with spike-duration cutoffs of ≥0.7 ms for projection cells and ≤0.5 ms for interneurons, this approach should keep instances of misclassifications to a minimum.

scholarly journals Stroke increases ischemia-related decreases in motor unit discharge rates

2018 ◽  
Vol 120 (6) ◽  
pp. 3246-3256 ◽  
Author(s):  
Spencer A. Murphy ◽  
Francesco Negro ◽  
Dario Farina ◽  
Tanya Onushko ◽  
Matthew Durand ◽  
...  
Keyword(s):  
Motor Unit ◽  
Time Constant ◽  
Motor Units ◽  
Unit Discharge ◽  
Firing Rates ◽  
Sensory Pathways ◽  
Discharge Rates ◽  
Motor Unit Firing ◽  
Motor Unit Discharge ◽  
Density Surface

Following stroke, hyperexcitable sensory pathways, such as the group III/IV afferents that are sensitive to ischemia, may inhibit paretic motor neurons during exercise. We quantified the effects of whole leg ischemia on paretic vastus lateralis motor unit firing rates during submaximal isometric contractions. Ten chronic stroke survivors (>1 yr poststroke) and 10 controls participated. During conditions of whole leg occlusion, the discharge timings of motor units were identified from decomposition of high-density surface electromyography signals during repeated submaximal knee extensor contractions. Quadriceps resting twitch responses and near-infrared spectroscopy measurements of oxygen saturation as an indirect measure of blood flow were made. There was a greater decrease in paretic motor unit discharge rates during the occlusion compared with the controls (average decrease for stroke and controls, 12.3 ± 10.0% and 0.1 ± 12.4%, respectively; P < 0.001). The motor unit recruitment thresholds did not change with the occlusion (stroke: without occlusion, 11.68 ± 5.83%MVC vs. with occlusion, 11.11 ± 5.26%MVC; control: 11.87 ± 5.63 vs. 11.28 ± 5.29%MVC). Resting twitch amplitudes declined similarly for both groups in response to whole leg occlusion (stroke: 29.16 ± 6.88 vs. 25.75 ± 6.78 Nm; control: 38.80 ± 13.23 vs 30.14 ± 9.64 Nm). Controls had a greater exponential decline (lower time constant) in oxygen saturation compared with the stroke group (stroke time constant, 22.90 ± 10.26 min vs. control time constant, 5.46 ± 4.09 min; P < 0.001). Ischemia of the muscle resulted in greater neural inhibition of paretic motor units compared with controls and may contribute to deficient muscle activation poststroke. NEW & NOTEWORTHY Hyperexcitable inhibitory sensory pathways sensitive to ischemia may play a role in deficient motor unit activation post stroke. Using high-density surface electromyography recordings to detect motor unit firing instances, we show that ischemia of the exercising muscle results in greater inhibition of paretic motor unit firing rates compared with controls. These findings are impactful to neurophysiologists and clinicians because they implicate a novel mechanism of force-generating impairment poststroke that likely exacerbates baseline weakness.

Mean-Field Approximations for Coupled Populations of Generalized Linear Model Spiking Neurons with Markov Refractoriness

2009 ◽  
Vol 21 (5) ◽  
pp. 1203-1243 ◽  
Author(s):  
Taro Toyoizumi ◽  
Kamiar Rahnama Rad ◽  
Liam Paninski
Keyword(s):  
Linear Model ◽  
Generalized Linear Model ◽  
Mean Field ◽  
Process Models ◽  
Network Activity ◽  
Direct Monte Carlo Simulation ◽  
Field Methods ◽  
Firing Rates ◽  
Cross Correlations ◽  
Mean Field Approximations

There has recently been a great deal of interest in inferring network connectivity from the spike trains in populations of neurons. One class of useful models that can be fit easily to spiking data is based on generalized linear point process models from statistics. Once the parameters for these models are fit, the analyst is left with a nonlinear spiking network model with delays, which in general may be very difficult to understand analytically. Here we develop mean-field methods for approximating the stimulus-driven firing rates (in both the time-varying and steady-state cases), auto- and cross-correlations, and stimulus-dependent filtering properties of these networks. These approximations are valid when the contributions of individual network coupling terms are small and, hence, the total input to a neuron is approximately gaussian. These approximations lead to deterministic ordinary differential equations that are much easier to solve and analyze than direct Monte Carlo simulation of the network activity. These approximations also provide an analytical way to evaluate the linear input-output filter of neurons and how the filters are modulated by network interactions and some stimulus feature. Finally, in the case of strong refractory effects, the mean-field approximations in the generalized linear model become inaccurate; therefore, we introduce a model that captures strong refractoriness, retains all of the easy fitting properties of the standard generalized linear model, and leads to much more accurate approximations of mean firing rates and cross-correlations that retain fine temporal behaviors.

scholarly journals Cell-type-specific control of basolateral amygdala neuronal circuits via entorhinal cortex-driven feedforward inhibition

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
E Mae Guthman ◽  
Joshua D Garcia ◽  
Ming Ma ◽  
Philip Chu ◽  
Serapio M Baca ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Basolateral Amygdala ◽  
Vital Role ◽  
Sensory Stimuli ◽  
Cell Type Specific ◽  
Fast Spiking ◽  
Patch Clamp Electrophysiology ◽  
Unsupervised Cluster Analysis ◽  
Feedforward Inhibition

The basolateral amygdala (BLA) plays a vital role in associating sensory stimuli with salient valence information. Excitatory principal neurons (PNs) undergo plastic changes to encode this association; however, local BLA inhibitory interneurons (INs) gate PN plasticity via feedforward inhibition (FFI). Despite literature implicating parvalbumin expressing (PV+) INs in FFI in cortex and hippocampus, prior anatomical experiments in BLA implicate somatostatin expressing (Sst+) INs. The lateral entorhinal cortex (LEC) projects to BLA where it drives FFI. In the present study, we explored the role of interneurons in this circuit. Using mice, we combined patch clamp electrophysiology, chemogenetics, unsupervised cluster analysis, and predictive modeling and found that a previously unreported subpopulation of fast-spiking Sst+ INs mediate LEC→BLA FFI.

Focal Synchronization of Ripples (80–200 Hz) in Neocortex and Their Neuronal Correlates

2001 ◽  
Vol 86 (4) ◽  
pp. 1884-1898 ◽  
Author(s):  
François Grenier ◽  
Igor Timofeev ◽  
Mircea Steriade
Keyword(s):  
Slow Wave ◽  
Slow Wave Sleep ◽  
Spiking Neurons ◽  
Slow Oscillation ◽  
Field Potentials ◽  
Firing Rates ◽  
Neuronal Excitation ◽  
Neocortical Neurons ◽  
Fast Spiking ◽  
Fast Oscillations

Field potentials from different neocortical areas and intracellular recordings from areas 5 and 7 in acutely prepared cats under ketamine-xylazine anesthesia and during natural states of vigilance in chronic experiments, revealed the presence of fast oscillations (80–200 Hz), termed ripples. During anesthesia and slow-wave sleep, these oscillations were selectively related to the depth-negative (depolarizing) component of the field slow oscillation (0.5–1 Hz) and could be synchronized over ∼10 mm. The dependence of ripples on neuronal depolarization was also shown by their increased amplitude in field potentials in parallel with progressively more depolarized values of the membrane potential of neurons. The origin of ripples was intracortical as they were also detected in small isolated slabs from the suprasylvian gyrus. Of all types of electrophysiologically identified neocortical neurons, fast-rhythmic-bursting and fast-spiking cells displayed the highest firing rates during ripples. Although linked with neuronal excitation, ripples also comprised an important inhibitory component. Indeed, when regular-spiking neurons were recorded with chloride-filled pipettes, their firing rates increased and their phase relation with ripples was modified. Thus besides excitatory connections, inhibitory processes probably play a major role in the generation of ripples. During natural states of vigilance, ripples were generally more prominent during the depolarizing component of the slow oscillation in slow-wave sleep than during the states of waking and rapid-eye movement (REM) sleep. The mechanisms of generation and synchronization, and the possible functions of neocortical ripples in plasticity processes are discussed.

scholarly journals Cell type specific control of basolateral amygdala plasticity via feedforward inhibition

2018 ◽  
Author(s):  
E. Mae Guthman ◽  
Ming Ma ◽  
Philip Chu ◽  
Serapio M. Baca ◽  
Diego Restrepo ◽  
...  
Keyword(s):  
Basolateral Amygdala ◽  
Vital Role ◽  
Extensive Literature ◽  
Sensory Stimuli ◽  
Cell Type Specific ◽  
Fast Spiking ◽  
Plastic Changes ◽  
Patch Clamp Electrophysiology ◽  
Specific Control ◽  
Unsupervised Cluster Analysis

AbstractThe basolateral amygdala (BLA) plays a vital role in associating specific sensory stimuli with salient valence information. Excitatory principal neurons (PNs) undergo plastic changes to encode this integrated sensory-valence information; however, local BLA inhibitory interneurons (INs) gate the plasticity of the PNs via feed forward inhibition (FFI). Despite extensive literature implicating parvalbumin expressing (PV+) INs in FFI in cortex and hippocampus, prior anatomical experiments in BLA implicate somatostatin expressing (Sst+) INs in BLA. In the present study, we combined patch clamp electrophysiology with chemogenetics, unsupervised cluster analysis, and predictive modeling and found that a previously unreported subpopulation of fast-spiking Sst+ INs mediate BLA FFI and gate plasticity.

scholarly journals Response Transformation and Receptive-Field Synthesis in the Lemniscal Trigeminothalamic Circuit

2003 ◽  
Vol 90 (3) ◽  
pp. 1556-1570 ◽  
Author(s):  
Brandon S. Minnery ◽  
Randy M. Bruno ◽  
Daniel J. Simons
Keyword(s):  
Receptive Field ◽  
Thalamic Nucleus ◽  
Spontaneous Firing ◽  
Plateau Phase ◽  
Afferent Signal ◽  
Firing Rates ◽  
Evoked Activity ◽  
Nucleus Principalis ◽  
Response Transformation ◽  
Stimulus Direction

To understand how the lemniscal trigeminothalamic circuit (PrV → VPM) of the rodent whisker-to-barrel pathway transforms afferent signals, we applied ramp-and-hold deflections to individual whiskers of lightly narcotized rats while recording the extracellular responses of neurons in either the ventroposterior medial (VPM) thalamic nucleus or in brain stem nucleus principalis (PrV). In PrV, only those neurons antidromically determined to project to VPM were selected for recording. We found that VPM neurons exhibited smaller response magnitudes and greater spontaneous firing rates than those of their PrV inputs, but that both populations were similarly well tuned for stimulus direction. In addition, fewer VPM (74%) than PrV neurons (93%) responded with sustained, or tonic, discharges during the plateau phase of the stimulus. Neurons in both populations responded most robustly to deflections of a single, “principal whisker” (PW), and the majority of cells in both PrV (90%) and VPM (73%) also responded to deflections of at least one adjacent whisker (AW). AW responses in both nuclei occurred on average at longer latencies and were more temporally dispersed than PW responses. Lateral inhibition, as evidenced by AW-evoked activity suppression, was rare in PrV but prevalent in VPM. In both nuclei, however, suppression was weak, with AW responses being on average excitatory. Our results suggest that the receptive-field structures and response properties of individual VPM neurons can be explained in large part by input from one or a small number of PrV neurons, but that intrathalamic mechanisms act to further transform the afferent signal.

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