Sensory Pathways in the Dorsal Funiculus

My thesis studies had stimulated an interest in the mamillothalamic pathways but also some puzzlement because we knew nothing about the nature of the messages passing along these pathways. Several laboratories were studying the thalamic relay of sensory pathways with great success during my post-doctoral years. Each sensory relay could be understood in terms of the appropriate sensory input, but we had no way of knowing the meaning of the mamillothalamic messages. I introduce these nuclei as an example of the many thalamic nuclei about whose input functions we still know little or nothing. Early clinical studies of mamillary lesions had suggested a role in memory formation, whereas evidence from cortical lesions suggested a role in emotional experiences. Studies of the smallest of the three nuclei forming these pathways then showed it to be concerned with sensing head direction, relevant but not sufficient for defining an animal’s position in space. More recent studies based on studies of cortical activity or cortical damage have provided a plethora of suggestions: as so often, the answers reported depend on the questions asked. That simple conclusion is relevant for all transthalamic pathways. The evidence introduced in Chapter 1, that thalamocortical messages have dual meanings, suggests that we need to rethink our questions. It may prove useful to look at the motor outputs of relevant cortical areas to get clues about some appropriate questions.

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Earless toads sense low frequencies but miss the high notes

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.1670 ◽

2017 ◽

Vol 284 (1864) ◽

pp. 20171670 ◽

Cited By ~ 10

Author(s):

Molly C. Womack ◽

Jakob Christensen-Dalsgaard ◽

Luis A. Coloma ◽

Juan C. Chaparro ◽

Kim L. Hoke

Keyword(s):

High Frequency ◽

Species Differences ◽

Low Frequency ◽

Auditory Brainstem ◽

Low Frequencies ◽

Hearing Sensitivity ◽

Sensory Pathways ◽

Airborne Sound ◽

Vibrational Sensitivity ◽

Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

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Innate Immune DNA Sensing of Flaviviruses

Viruses ◽

10.3390/v12090979 ◽

2020 ◽

Vol 12 (9) ◽

pp. 979

Author(s):

Tongtong Zhu ◽

Ana Fernandez-Sesma

Keyword(s):

Innate Immune System ◽

Rna Viruses ◽

Innate Immune ◽

Host Factors ◽

Dna Sensing ◽

Antiviral Responses ◽

Sensory Pathways ◽

Sensing System ◽

Positive Sense ◽

Successful Replication

Flaviviruses are arthropod-borne RNA viruses that have been used extensively to study host antiviral responses. Often selected just to represent standard single-stranded positive-sense RNA viruses in early studies, the Flavivirus genus over time has taught us how truly unique it is in its remarkable ability to target not just the RNA sensory pathways but also the cytosolic DNA sensing system for its successful replication inside the host cell. This review summarizes the main developments on the unexpected antagonistic strategies utilized by different flaviviruses, with RNA genomes, against the host cyclic GAMP synthase (cGAS)/stimulator of interferon genes (STING) cytosolic DNA sensing pathway in mammalian systems. On the basis of the recent advancements on this topic, we hypothesize that the mechanisms of viral sensing and innate immunity are much more fluid than what we had anticipated, and both viral and host factors will continue to be found as important factors contributing to the host innate immune system in the future.

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Intraoperative monitoring for tethered cord surgery: an update

Neurosurgical FOCUS ◽

10.3171/foc.2004.16.2.1 ◽

2004 ◽

Vol 16 (2) ◽

pp. E8 ◽

Cited By ~ 71

Author(s):

Karl F. Kothbauer ◽

Klaus Novak

Keyword(s):

Electrical Stimulation ◽

Anal Sphincter ◽

External Anal Sphincter ◽

Continuous Monitoring ◽

Pudendal Nerve ◽

Tethered Cord ◽

Sensory Pathways ◽

Functional Integrity ◽

Muscle Responses ◽

Stimulation Of

Object Intraoperative neurophysiological recording techniques have found increasing use in neurosurgical practice. The development of new recording techniques feasible while the patient receives a general anesthetic have improved their practical use in a similar way to the use of digital recording, documentation, and video technology. This review intends to provide an update on the techniques used and their validity. Methods Two principal methods are used for intraoperative neurophysiological testing during tethered cord release. Mapping identifies functional neural structures, namely nerve roots, and monitoring provides continuous information on the functional integrity of motor and sensory pathways as well as reflex circuitry. Mapping is performed mostly by using direct electrical stimulation of a structure within the surgical field and recording at a distant site, usually a muscle. Sensory mapping can also be performed with peripheral stimulation and recording within the surgical site. Monitoring of the motor system is achieved with motor evoked potentials. These are evoked by transcranial electrical stimulation and recorded from limb muscles and the external anal sphincter. The presence or absence of muscle responses are the parameters monitored. Sensory potentials evoked by tibial or pudendal nerve stimulation and recorded from the dorsal columns via an epidurally inserted electrode and/or from the scalp as cortical responses are used to access the integrity of sensory pathways. Amplitudes and latencies of these responses are then interpreted. The bulbocavernosus reflex, with stimulation of the pudendal nerve and recording of muscle responses in the external anal sphincter, is used for continuous monitoring of the reflex circuitry. Presence or absence of this response is the pertinent parameter that is monitored. Conclusions Intraoperative neurophysiology provides a wide and reliable set of techniques for intraoperative identification of neural structures and continuous monitoring of their functional integrity.

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