Sensitivity to change in heartbeats as interoceptive ability

What is the nature of autonomic signals and how do they shape introception? This study presents a new method for evaluating cardiac interoceptive ability, measuring sensitivity to naturalistic changes in the number of heartbeats over time periods. The results of this research show participants have an overall tendency towards sensing fewer heartbeats during higher heart rates. This likely reflects the influence of changing heartbeat strength on cardiac interoception at rest, which should be taken into account when evaluating cardiac interoceptive ability and its relationship to anxiety and psychosomatic conditions. Take a listen to this podcast as Dr. Sarah Garfinkel of the University College London discusses the recently published research “Sensitivity to changes in rate of heartbeats as a measure of interoceptive ability” with Editor-in-Chief Professor Nino Ramirez.

Dennis E. O. Larsson, Giulia Esposito, Hugo D. Critchley, Zoltan Dienes, and Sarah N. Garfinkel

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Oscillatory entrainment mechanisms and anticipatory predictive processes in children with autism spectrum disorder

In this podcast the authors Dr. Shlomit Beker and Dr. Sophie Molholm of Albert Einstein College of Medicine discuss their recently published manuscript titled “Oscillatory entrainment mechanisms and anticipatory predictive processes in Children with Autism Spectrum Disorder (ASD)” with Editor-in-Chief Prof. Jan-Marino (Nino) Ramirez. In their paper they, along with co-author John Foxe, used EEG and behavior to index predictive processes in children with ASD.  A condition in which an auditory target was cued by a rhythmically predictable sequence of visual stimuli was compared to a condition in which the visual cues were absent. Neurophysiological measures of predictive processing, namely preparatory activity and neural entrainment were impaired in the ASD group, whereas behavioral measures of predictive processing were intact.  When sensory events are presented in a predictable temporal pattern, performance and neuronal responses in ASD may be governed more by the occurrence of the events themselves and less by their anticipated timing.  Listen today!

Check out the article here: https://doi.org/10.1152/jn.00329.2021 

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Forms of explanation and understanding for neuroscience and artificial intelligence

In this podcast author Dr. Jessica Thompson of the University of Oxford discusses her recently published manuscript titled "Forms of explanation and understanding for neuroscience and artificial intelligence" with Editor-in-Chief  Prof. Jan-Marino (Nino) Ramirez and Associate Editor Dr. John W. Krakauer.  Much of the controversy evoked by the use of deep neural networks as models of biological neural systems amount to debates over what constitutes scientific progress in neuroscience. In order to discuss what constitutes scientific progress, one must have a goal in mind (progress towards what?). One such long term goal is to produce scientific explanations of intelligent capacities (e.g., object recognition, relational reasoning). I argue that the most pressing philosophical questions at the intersection of neuroscience and artificial intelligence are ultimately concerned with defining the phenomena to be explained and with what constitute valid explanations of such phenomena. I propose that a foundation in the philosophy of scientific explanation and understanding can scaffold future discussions about how an integrated science of intelligence might progress. Towards this vision, I review relevant theories of scientific explanation and discuss strategies for unifying the scientific goals of neuroscience and AI.

https://doi.org/10.1152/jn.00195.2021

Temporal Differences between Load and Movement Signal Integration in the Sensorimotor Network of an Insect Leg

Listen as coauthors Dr. Corinna Gebehart and Prof. Ansgar Büschges of the University of Cologne talk about their recently published manuscript "Temporal Differences between Load and Movement Signal Integration in the Sensorimotor Network of an Insect Leg" with Editor-in-Chief Prof. Jan-Marino (Nino) Ramirez. In this podcast the authors discuss  temporal differences in the processing of two distinct sensory modalities generated by the sensorimotor network and affecting motor output. The authors found that the reported temporal differences in sensory processing and signal integration improve our understanding of sensory network computation and function in motor control.

Corinna Gebehart, Ansgar Büschges

https://doi.org/10.1152/jn.00399.2021 

JNP Discusses Experimental Biology 2022 with the Central Nervous System Section

In our latest podcast Prof. Nino Ramirez discusses Experimental Biology 2022 with Central Nervous System section's, Dr. Janice Urban, Chair of the Steering Committee. Listen now to learn about what is coming up for CNS at Experimental Biology, along with new call for papers the journal will be launching after Experimental Biology. For more information on Experimental Biology 2022 please go to www.experimentalbiology.org . To learn more about the journal and section please go to www.physiology.org. If you are interested in submitting a manuscript and have questions, please email Jami Jones at jjones@physiology.org 

New insights into how general anesthetics interfere with memory formation

What are the most important classes of anesthetics and their use? Do anesthetics affect GABA-A receptor expression or composition?  In this podcast author Dr. Robert Pearce of the University of Wisconsin-Madison discusses these questions and more as he goes over his recent research titled “ Hippocampal β2-GABA-A receptors mediate LTP suppression by etomidate and contribute to long-lasting feedback but not feedforward inhibition of pyramidal neurons” with Editor-in-Chief Prof. Nino Ramirez.  Etomidate exerts its anesthetic actions through GABA-A receptors. But exactly how does this prevent memories from being formed? Here, using a hippocampal brain slice model, Dr. Pearce and his colleagues showed that GABA-A receptors that incorporate the β2 subunit are essential to LTP suppression by etomidate. They also showed that although these receptors are found primarily on interneurons, β2-GABA-A receptors on pyramidal neurons do contribute to long-lasting inhibition, through feedback, but not feedforward, circuits. Their results have direct implications for understanding how anesthetics block memory formation, and also more generally how inhibitory circuits control learning and memory.

Alexander G. Figueroa, Claudia Benkwitz, Gabe Surges, Nicholas Kunz, Gregg E. Homanics, and Robert A. Pearce

Hippocampal β2-GABAA receptors mediate LTP suppression by etomidate and contribute to long-lasting feedback but not feedforward inhibition of pyramidal neurons

https://doi.org/10.1152/jn.00303.2021 

The orchestration of the sympathetic response

Most of us have heard about the Flight and Fight response and the activation of the sympathetic system. But, what is often overlooked is the sheer complexity of sympathetic activation as it differentially and specifically modulates different organ systems. Different stressors activate and inhibit specific target organs, including specific muscle groups. Understanding the mechanisms how the central and peripheral nervous system interacts to control such a highly differentiated sympathetic response is challenging and we are just beginning to get a first taste of this fascinating task that our nervous system accomplishes without us being aware of it. Given the complexity of sympathetic control it should not be surprising that it can also fail and become a source of dysautonomia and other disorders. In this podcast, senior author Professor Philip Millar of the University of Guelph discusses the orchestration of the sympathetic activation with Editor-in-Chief Professor Nino Ramirez. They base their discussion on the author’s recently published manuscript “Muscle sympathetic single-unit responses during rhythmic handgrip exercise and isocapnic hypoxia in males: the role of sympathoexcitation magnitude”. Listening to this podcast you will gain not only insights into this particular manuscript, but it will raise your awareness of the astonishingly differentiated sympathetic activation in health and disease. You will also learn how microneurography can be used to characterize  specific subpopulations of muscle sympathetic single units as they are activated and inhibited during mild sympathoexcitatory stress. Listen today!

Anthony V. Incognito, André L. Teixeira, Brooke M. Shafer, Massimo Nardone, Tyler D. Vermeulen, Glen E. Foster, and Philip J. Millar Muscle sympathetic single-unit responses during rhythmic handgrip exercise and isocapnic hypoxia in males: the role of sympathoexcitation magnitude Journal of Neurophysiology

https://doi.org/10.1152/jn.00678.2020  

A Discussion on Postural mechanisms in moderate-to-severe cerebral palsy with Dr. Goodworth and Dr. Saavedra

In this podcast coauthors Dr. Adam Goodworth of Westmont College and Dr. Sandra Saavedra of the University of Hartford discuss their manuscript titled “Postural mechanisms in moderate-to-severe cerebral palsy” with Editor in Chief Prof. Nino Ramirez. Cerebral palsy (CP) is the most common cause of motor disability in children. People with moderate-to-severe CP are typically non-ambulatory and have major impairments in trunk postural control. Dr. Saavedra has tremendous clinical experience in treating children with CP and shares in this podcast her clinical insights and why she realized how important it is to collaborate with engineers to better help children with CP. Dr. Goodworth is an inventor and engineer who closely works with Dr. Saavedra to understand the postural challenges faced by children with CP. Together they published the first systems identification study to investigate postural responses to external stimulus. They hypothesize at how the atypical postural control system functions with use of an experimentally validated feedback model.

Adam Goodworth and Sandra Saavedra

https://doi.org/10.1152/jn.00549.2020 

Event-related synchronization/desynchronization and functional neuroanatomical regions associated with fatigue effects on cognitive flexibility

In our current society, multimedia use is particularly prevalent. It has become increasingly normal to multitask, which requires cognitive flexibility. How do we focus without getting fatigued at the same time? Would you think that the data on fatigability bears information about possible changes in people with “burnout” or other forms of “fatigue”?  What is happening in our brain when we fatigue by pursuing our daily tasks? Author, Professor Christian Beste of Dresden University of Technology discusses these questions and more with Editor in Chief  Professor Jan-Marino (Nino) Ramirez in our latest podcast. Cognitive flexibility is an essential prerequisite for goal-directed behavior and daily observations already show that it deteriorates when one is engaged in a task for (too) long time. Yet, the neural mechanisms underlying such fatigability effect in cognitive flexibility are poorly understood. We examined how theta, alpha and beta frequency event-related synchronization and desynchronization processes during a cued memory-based task switching are modulated by time-on-task effects. We put special emphasis on the examination of functional neuroanatomical regions being associated with these modulations using EEG-beamforming. We show clear declines in task switching performance (increased switch costs) with time on task. For processes occurring before rule switching or repetition processes, we show that anticipatory attentional sampling and selection mechanisms associated with fronto-parietal structures are modulated by time on task effects, but also sensory areas (occipital cortex) show fatigability-dependent modulations. After target stimulus presentation, the allocation of processing resources for response selection as reflected by theta-related activity in parietal cortices is compromised with time-on-task. Similarly, seem to a concomitant increase in alpha and beta band related attentional processing or gating mechanisms in frontal and occipital regions. Yet, considering the behavioral data showing an apparent decline in performance, this probably compensatory increase is still insufficient to allow reasonable performance. The same is likely the case for processes occurring before rule switching or repetition processes. Comparative analyses show that modulations of alpha band activity are as strongly modulated by fatigability as theta band activity. Implications of these findings for theoretical concepts on fatigability are discussed.

Shijing Yu, Moritz Mückschel, and Christian Beste

Read the manuscript here: https://doi.org/10.1152/jn.00228.2021 

Evaluation of force feedback in walking using joint torques as ‘naturalistic‘ stimuli

What are the common features of force detection in vertebrates, insects and walking machines?  Do the sense organs signal different force qualities at different joints? In the podcast coauthors Professor Sasha Zill of Marshall University, Dr. Nicholas Szcecinski of the University of West Virginia and Professor Ansgar Büschges of the University of Cologne join Editor in Chief Professor Nino Ramirez to delve deeper into their manuscript titled “Evaluation of force feedback in walking using joint torques as 'naturalistic' stimuli.”  Sensory encoding of forces during walking by campaniform sensilla was characterized in stick insects using waveforms of joint torques calculated by inverse dynamics as mechanical stimuli. Tests using the mean joint torque and torques of individual steps showed the system is highly sensitive to force dynamics (dF/dt). Use of 'naturalistic' stimuli can reproduce characteristics of sensory discharges seen in freely walking insects, such as load transfer among legs.

https://doi.org/10.1152/jn.00120.2021