Neural responses to simple simulated echoes in the auditory brain stem of the unanesthetized rabbit

1995 ◽  
Vol 74 (6) ◽  
pp. 2469-2486 ◽  
Author(s):  
D. C. Fitzpatrick ◽  
S. Kuwada ◽  
R. Batra ◽  
C. Trahiotis
Keyword(s):  
Time Course ◽  
Superior Olivary Complex ◽  
Precedence Effect ◽  
Natural Environments ◽  
Complete Suppression ◽  
Sound Waves ◽  
Neural Basis ◽  
Unanesthetized Rabbit ◽  
Echo Threshold ◽  
Time Required

1. In most natural environments, sound waves from a single source will reach a listener through both direct and reflected paths. Sound traveling the direct path arrives first, and determines the perceived location of the source despite the presence of reflections from many different locations. This phenomenon is called the "law of the first wavefront" or "precedence effect." The time at which the reflection is first perceived as a separately localizable sound defines the end of the precedence window and is called "echo threshold." The precedence effect represents an important property of the auditory system, the neural basis for which has only recently begun to be examined. Here we report the responses of single neurons in the inferior colliculus (IC) and superior olivary complex (SOC) of the unanesthetized rabbit to a sound and its simulated reflection. 2. Stimuli were pairs of monaural or binaural clicks delivered through earphones. The leading click, or conditioner, simulated a direct sound, and the lagging click, or probe, simulated a reflection. Interaural time differences (ITDs) were introduced in the binaural conditioners and probes to adjust their simulated locations. The probe was always set at the neuron's best ITD, whereas the conditioner was set at the neuron's best ITD or its worst ITD. To measure the time course of the effects of the conditioner on the probe, we examined the response to the probe as a function of the conditioner-probe interval (CPI). 3. When IC neurons were tested with conditioners and probes set at the neuron's best ITD, the response to the probe as a function of CPI had one of two forms: early-low or early-high. In early-low neurons the response to the probe was initially suppressed but recovered monotonically at longer CPIs. Early-high neurons showed a nonmonotonic recovery pattern. In these neurons the maximal suppression did not occur at the shortest CPIs, but rather after a period of less suppression. Beyond this point, recovery was similar to that of early-low neurons. The presence of early-high neurons meant that the overall population was never entirely suppressed, even at short CPIs. Taken as a whole. CPIs for 50% recovery of the response to the probe among neurons ranged from 1 to 64 ms with a median of approximately 6 ms. 4. The above results are consistent with the time course of the precedence effect for the following reasons. 1) The lack of complete suppression at any CPI is compatible with behavioral results that show the presence of a probe can be detected even at short CPIs when it is not separately localizable. 2) At a CPI corresponding to echo threshold for human listeners (approximately 4 ms CPI) there was a considerable response to the probe, consistent with it being heard as a separately localizable sound at this CPI. 3) Full recovery for all neurons required a period much longer than that associated with the precedence effect. This is consistent with the relatively long time required for conditioners and probes to be heard with equal loudness. 5. Conditioners with either the best ITD or worst ITD were used to determine the effect of ITD on the response to the probe. The relative amounts of suppression caused by the two ITDs varied among neurons. Some neurons were suppressed about equally by both types of conditioners, others were suppressed more by a conditioner with the best ITD, and still others by a conditioner with the worst ITD. Because the best ITD and worst ITD presumably activate different pathways, these results suggest that different neurons receive a different balance of inhibition from different sources. 6. The recovery functions of neurons not sensitive to ITDs were similar to those of ITD-sensitive, neurons. This suggests that the time course of suppression may be common among different IC populations. 7. We also studied neurons in the SOC. Although many showed binaural interactions, none were sensitive to ITDs. Thus the response of this population may not be

scholarly journals Early changes in corticomotor excitability underlie proactive inhibitory control of error correction

2021 ◽  
Author(s):  
Borja Rodriguez Herreros ◽  
Julia L Amengual ◽  
Jimena Lucrecia Vazquez-Anguiano ◽  
Silvio Ionta ◽  
Carlo Miniussi ◽  
...  
Keyword(s):  
Inhibitory Control ◽  
Time Course ◽  
Decisive Role ◽  
Neural Correlates ◽  
Proactive Inhibition ◽  
Conclusive Evidence ◽  
Inhibitory Mechanism ◽  
Neural Basis ◽  
Corticomotor Excitability ◽  
Control Of Error

Converging evidence indicates that response inhibition may arise from the interaction of effortful proactive and reflexive reactive mechanisms. However, the distinction between the neural basis sustaining proactive and reactive inhibitory processes is still unclear. To identify reliable neural markers of proactive inhibition, we examined the behavioral and electrophysiological correlates elicited by manipulating the degree of inhibitory control in a task that involved the detection and amendment of errors. Restraining or encouraging the correction of errors did not affect the time course of the behavioral and neural correlates associated to reactive inhibition. We rather found that a bilateral and sustained decrease of corticomotor excitability was required for an effective proactive inhibitory control, whereas selective strategies were associated with defective response suppression. Our results provide behavioral and electrophysiological conclusive evidence of a comprehensive proactive inhibitory mechanism, with a distinctive underlying neural basis, governing the commission and amendment of errors. Together, these findings hint at a decisive role for changes in corticomotor excitability in determining whether an action will be successfully suppressed.

Apparent diffusion time of oxygen from blood to tissue in rat cerebral cortex: implication for tissue oxygen dynamics during brain functions

2007 ◽  
Vol 103 (4) ◽  
pp. 1352-1358 ◽  
Author(s):  
Kazuto Masamoto ◽  
Jeff Kershaw ◽  
Masakatsu Ureshi ◽  
Naosada Takizawa ◽  
Hirosuke Kobayashi ◽  
...  
Keyword(s):  
Time Course ◽  
Oxygen Demand ◽  
Excess Demand ◽  
Tissue Oxygen ◽  
Doppler Flowmetry ◽  
Demand And Supply ◽  
Brain Functions ◽  
Apparent Diffusion ◽  
Time Required ◽  
Stimulus Length

To investigate the dynamics of tissue oxygen demand and supply during brain functions, we simultaneously recorded Po2 and local cerebral blood flow (LCBF) with an oxygen microelectrode and laser Doppler flowmetry, respectively, in rat somatosensory cortex. Electrical hindlimb stimuli were applied for 1, 2, and 5 s to vary the duration of evoked cerebral metabolic rate of oxygen (CMRO2). The electrical stimulation induced a robust increase in Po2 (4–9 Torr at peak) after an increase in LCBF (14–26% at peak). A consistent lag of ∼1.2 s (0.6–2.3 s for individual animals) in the Po2 relative to LCBF was found, irrespective of stimulus length. It is argued that the lag in Po2 was predominantly caused by the time required for oxygen to diffuse through tissue. During brain functions, the supply of fresh oxygen further lagged because of the latency of LCBF onset (∼0.4 s). The results indicate that the tissue oxygen supports excess demand until the arrival of fresh oxygen. However, a large drop in Po2 was not observed, indicating that the evoked neural activity demands little extra oxygen or that the time course of excess demand is as slow as the increase in supply. Thus the dynamics of Po2 during brain functions predominantly depend on the time course of LCBF. Possible factors influencing the lag between demand and supply are discussed, including vascular spacing, reactivity of the vessels, and diffusivity of oxygen.

Prolonged aspirin inhibition of anodal vasodilation is not due to the trafficking delay of neural mediators

2003 ◽  
Vol 285 (1) ◽  
pp. R155-R161 ◽  
Author(s):  
S. Durand ◽  
B. Fromy ◽  
M. Tartas ◽  
A. Jardel ◽  
J. L. Saumet ◽  
...  
Keyword(s):  
Time Course ◽  
Nerve Endings ◽  
High Dose ◽  
Current Application ◽  
Cutaneous Vasodilation ◽  
Dose Aspirin ◽  
Proximal Site ◽  
Time Required ◽  
Distal Site ◽  
High Dose Aspirin

We previously reported that forearm vasodilation to a delivered all-at-once over 5 min or a 1-min repeated monopolar anodal 0.10-mA current application is aspirin sensitive and that a single high-dose aspirin exerts a long-lived effect in the former case. We hypothesized that 1) in the latter case, the effect of aspirin would also be long lived and 2) the time required to resupply nerve endings with unblocked cyclooxygenase through axonal transport could explain this phenomenon. We studied the time course for the recovery of vasodilation to repeated current application after placebo or 1-g aspirin treatment. We then searched for a difference at a proximal vs. distal site in the recovery of the response. Aspirin abolished current-induced vasodilation at 2 h, 10 h, and 3 days, with a progressive recovery thereafter, but no difference between distal and proximal site was observed for the recovery of the response. This suggests that, although neural cyclooxygenase could participate in the response, the time course of aspirin inhibition of current-induced cutaneous vasodilation is not due to the time required through neural transport to resupply nerve endings with unblocked proteins.

The Organization of Human Language Cortex: Special Adaptation or Common Cortical Design?

1997 ◽  
Vol 3 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Jeffrey J. Hutsler ◽  
Michael S. Gazzaniga
Keyword(s):  
Time Course ◽  
Human Language ◽  
Human Communication ◽  
Neural Basis ◽  
Language Abilities ◽  
Language Functions ◽  
Evolutionary Forces ◽  
Special Adaptation ◽  
Species Specific ◽  
The Brain

Understanding the neural basis of language is one of the oldest and most difficult pursuits in neuroscience. Despite decades of accumulated data on aphasic subjects with cortical damage, we still know relatively little of how language functions are represented within the neural circuitry of the brain. A major issue of debate is whether language is a species-specific adaptation built into the neocortex, or a by-product of neocortical expansion. Cognitive studies emphasizing the universal nature of language abilities, the consistencies of language structure, and the consistent time course of language development have all indicated that language abilities are innate and must be built into the brain by evolutionary forces. Comparative studies of primates are equivocal since we have little evidence indicating that primate communication is homologous to human language systems. Much of this confusion is related to a lack of information regarding the neural basis of human communication. Recent anatomical data from human brains indicates that left hemisphere regions can have unique types of organization that may be responsible for functional specialization.

scholarly journals Neural Correlates of Group Bias During Natural Viewing

2018 ◽  
Vol 29 (8) ◽  
pp. 3380-3389
Author(s):  
Timothy J Andrews ◽  
Ryan K Smith ◽  
Richard L Hoggart ◽  
Philip I N Ulrich ◽  
Andre D Gouws
Keyword(s):  
Time Course ◽  
Social Groups ◽  
Sensory Information ◽  
Brain Regions ◽  
Group Differences ◽  
Neural Basis ◽  
Brain Responses ◽  
The World ◽  
High Level ◽  
The Brain

Abstract Individuals from different social groups interpret the world in different ways. This study explores the neural basis of these group differences using a paradigm that simulates natural viewing conditions. Our aim was to determine if group differences could be found in sensory regions involved in the perception of the world or were evident in higher-level regions that are important for the interpretation of sensory information. We measured brain responses from 2 groups of football supporters, while they watched a video of matches between their teams. The time-course of response was then compared between individuals supporting the same (within-group) or the different (between-group) team. We found high intersubject correlations in low-level and high-level regions of the visual brain. However, these regions of the brain did not show any group differences. Regions that showed higher correlations for individuals from the same group were found in a network of frontal and subcortical brain regions. The interplay between these regions suggests a range of cognitive processes from motor control to social cognition and reward are important in the establishment of social groups. These results suggest that group differences are primarily reflected in regions involved in the evaluation and interpretation of the sensory input.

Potential Role of Sponge Spicules in Influencing the Silicon Biogeochemistry of Florida Lakes

1993 ◽  
Vol 50 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Daniel J. Conley ◽  
Claire L. Schelske
Keyword(s):  
Amorphous Silica ◽  
Biogenic Silica ◽  
Time Course ◽  
Potential Role ◽  
Complete Dissolution ◽  
Sediment Samples ◽  
Florida Lakes ◽  
Sponge Spicules ◽  
Time Required

Amorphous silica, e.g. biogenic silica (BSi), contained in diatoms and in sponge spicules was estimated by time course extraction from surficial sediment samples of 82 Florida lakes. Separation of diatom BSi from sponge BSi was based on the observation that diatoms completely dissolve within 2 h of digestion at 85 °C in 1% Na2CO3 whereas sponge spicules, which are generally larger than diatoms, take longer to dissolve. Sponge samples from four lakes in northern Wisconsin ranged widely in the time required to dissolve completely (1.5–12 h), but no significant differences were observed in the rates of dissolution among the lakes. In Florida lake sediments, diatom BSi averaged 49.2 (± 48.4) mg∙g−1 and sponge BSi averaged 31.5 (± 35.8) mg∙g−1, with sponge BSi comprising on average 40% of the total amorphous silica extracted. The procedure for separating diatom BSi from sponge BSi underestimates sponge BSi because smaller and/or lightly silicified components of sponges are completely dissolved early in the digestion. However, because sponge spicules comprise a significant fraction of total amorphous silica extracted, we hypothesize that sponge spicules, which on average are larger than diatoms and require a longer time for complete dissolution, may constitute an important sink for BSi in Florida lakes.

Chronic centrifugation (hypergravity) disrupts the circadian system of the rat

2003 ◽  
Vol 95 (3) ◽  
pp. 1266-1278 ◽  
Author(s):  
D. C. Holley ◽  
C. W. DeRoshia ◽  
M. M. Moran ◽  
C. E. Wade
Keyword(s):  
Circadian Rhythm ◽  
Time Course ◽  
Control Period ◽  
Circadian System ◽  
Deep Body Temperature ◽  
Periodicity Analysis ◽  
Time Required ◽  
Dose Dependent ◽  
Deep Body ◽  
Percent Decrease

The present study was conducted to evaluate the response of rat deep body temperature (DBT) and gross locomotor activity (LMA) circadian rhythms to acute hypergravity onset and adaptation to chronic (14 day) hypergravity exposure over three gravity intensities (1.25, 1.5, and 2 G). Centrifugation of unanesthetized naive animals resulted in a dramatic acute decrease in DBT (-1.45, -2.40, and -3.09°C for the 1.25, 1.5, and 2.0 G groups, respectively). LMA was suppressed for the duration of centrifugation (vs. control period); the percent decrease for each group on days 12-14, respectively, was 1.0 G, -15.2%, P = not significant; 1.25 G, -26.9%, P < 0.02; 1.5 G, -44.5%, P < 0.01; and 2.0 G, -63.1%, P < 0.002. The time required for DBT and LMA circadian rhythmic adaptation and stabilization to hypergravity onset increased from 1.25 to 2.0 G in all circadian metrics except daily means. Periodicity analysis detected the phenomenon of circadian rhythm splitting, which has not been reported previously in response to chronic hypergravity exposure. Our analysis documents the disruptive and dose-dependent effects of hypergravity on circadian rhythmicity and the time course of adaptation to 14-day chronic centrifugation exposure.

The neural and cognitive time course of intention reasoning: Electrophysiological evidence from ERPs

2020 ◽  
pp. 174702182097421
Author(s):  
Qin Jiang ◽  
Qi Wang ◽  
Hong Li
Keyword(s):  
Time Course ◽  
Cognitive Conflict ◽  
Conceptual Structure ◽  
Neural Correlates ◽  
Event Related Potential ◽  
Positive Component ◽  
Neural Basis ◽  
Late Positive Component ◽  
Different Types ◽  
Present Event

Intention is a typical mental state in the theory of mind. However, to date, there have been theoretical debates on the conceptual structure of intention. The neural and cognitive time course of intention reasoning remains unclear. The present event-related potential (ERP) study had two purposes: first, to investigate the neural correlates of intention reasoning based on a differentiated conceptual structure distinguishing desire and intention; second, to investigate the neural basis of intention reasoning for different agents. Thus, we compared the neural activity elicited by intention reasoning for self and for others when the intention matched or mismatched the desire of the agent. The results revealed that three ERP components distinguished among different types of intention reasoning. A negative-going ERP deflection with right frontal distribution between 400 and 500 ms might reflect the cognitive conflict involved in intention reasoning, a right frontal late positive component might be associated with the categorisation of agents, and a centro-parietal late slow wave might indicate the conceptual mental operations associated with decoupling mechanisms in intention processing. These findings implied the neural and cognitive time course of intention reasoning and provided neural evidence for the differentiated conception of intention.

scholarly journals Mechanisms and Dynamics of Cortical Motor Inhibition in the Stop-signal Paradigm: A TMS Study

2010 ◽  
Vol 22 (2) ◽  
pp. 225-239 ◽  
Author(s):  
Wery P. M. van den Wildenberg ◽  
Borís Burle ◽  
Franck Vidal ◽  
Maurits W. van der Molen ◽  
K. Richard Ridderinkhof ◽  
...  
Keyword(s):  
Time Course ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Single Pulse ◽  
Stop Signal ◽  
Neural Basis ◽  
Manual Response ◽  
Inhibitory Circuits ◽  
Voluntary Behavior

The ability to stop ongoing motor responses in a split-second is a vital element of human cognitive control and flexibility that relies in large part on prefrontal cortex. We used the stop-signal paradigm to elucidate the engagement of primary motor cortex (M1) in inhibiting an ongoing voluntary motor response. The stop-signal paradigm taps the ability to flexibly countermand ongoing voluntary behavior upon presentation of a stop signal. We applied single-pulse TMS to M1 at several intervals following the stop signal to track the time course of excitability of the motor system related to generating and stopping a manual response. Electromyography recorded from the flexor pollicis brevis allowed quantification of the excitability of the corticospinal tract and the involvement of intracortical GABABergic circuits within M1, indexed respectively by the amplitude of the motor-evoked potential and the duration of the late part of the cortical silent period (SP). The results extend our knowledge of the neural basis of inhibitory control in three ways. First, the results revealed a dynamic interplay between response activation and stopping processes at M1 level during stop-signal inhibition of an ongoing response. Second, increased excitability of inhibitory interneurons that drives SP prolongation was evident as early as 134 msec following the instruction to stop. Third, this pattern was followed by a stop-related reduction of corticospinal excitability implemented around 180 after the stop signal. These findings point to the recruitment of GABABergic intracortical inhibitory circuits within M1 in stop-signal inhibition and support the notion of stopping as an active act of control.

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