Application of the 2-Deoxy-&lt;i&gt;D&lt;/i&gt;-[&lt;sup&gt;14&lt;/sup&gt;C]-Glucose Method to the Mouse for Measuring Local Cerebral Glucose Utilization

Nowaczyk, T.; Rosiers, M.H. Des

doi:10.1159/000115227

Cited by 9 publications

(5 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In both deeply anesthetized and comatose patients, unresponsive to painful stimuli, auditory input increased SEMG amplitude. These observations are consistent with earlier work showing the presence of auditory evoked cortical potentials in anesthetized patients (2) and relatively high metabolic activity in the auditory structures of anesthetized rats and monkeys (13,16). Thus, the auditory evoked SEMG potential may eventually prove useful for monitoring subcortical function.…”

Section: ' 5isupporting

confidence: 92%

Quantitative surface electromyography in anesthesia and critical care

Edmonds

Couture

Stolzy

et al. 1986

International Journal of Clinical Monitoring and Computing

View full text Add to dashboard Cite

The frontalis muscle spontaneous (SEMG) and electrically evoked (EEMG) electromyograms were recorded in 4 different clinical settings. Using a standardized isoflurane-based anesthetic protocol. Study 1 examined the SEMG response to both surgical and acoustic stimuli. The acoustic SEMG response was also examined in comatose head-injured patients. Study 2 used the EEMG to compare the extent of vecuronium-induced neuromuscular blockade on the frontalis and hypothenar muscles in both anesthetized and comatose patients. In Study 3 head-injured comatose patients were used to investigate the relationship between SEMG changes and transient elevations in intracranial pressure (ICP). The effect of opiate analgesics on the pain-activated SEMG in conscious post-operative patients was investigated in Study 4. These studies illustrate the following phenomena. First, in conscious, unparalyzed or lightly anesthetized patients, painful (stressful) stimuli are associated with increases in SEMG amplitude. Thus, the SEMG may indicate periods of inadequate analgesia, not only post-operatively (Study 4) but also intra-operatively (Study 1), since we found the frontalis to be relatively insensitive to a non-depolarizing neuromuscular blocker (Study 2). However, the interpretation of intra-operative SEMG changes may be confounded by opiates (Study 4) and perhaps other agents capable of influencing the frontalis through either non-nociceptive central or peripheral mechanisms. Second, the opiate analgesics consistently decreased SEMG amplitude in non-tolerant conscious patients (Study 4. Although this opiate-induced decrease is not necessarily indicative of opiate analgesia, it may provide an objective, quantifiable measure of a central opiate effect. The SEMG is particularly well-suited to determine the precise timecourse of this effect. Third, in deeply anesthetized or comatose patients, unresponsive to either surgical or electrical stimulation. SEMG amplitude may increase in response to elevated ICP or certain sounds (Study 3). The stress (pain) and auditory-evoked SEMGs may thus provide measures of brainstem function that are independent of the level of consciousness.

show abstract

Section: ' 5isupporting

confidence: 92%

Quantitative surface electromyography in anesthesia and critical care

Edmonds

Couture

Stolzy

et al. 1986

International Journal of Clinical Monitoring and Computing

View full text Add to dashboard Cite

show abstract

“…Our work suggests that the mean firing rate of long distance-projecting neocortical pyramidal neurons may be relatively unvarying across species. Moreover, within a species, white matter metabolic rates at other neocortical locations appear to be similar: among neocortical regions that include both callosal and noncallosal tissue, the range of observed values is ϳ1.2-fold in mouse (Nowaczyk and Des Rosiers, 1981), in rat (Sokoloff et al, 1977;Collins et al, 1987), and in macaque (Kennedy et al, 1978;Shapiro et al, 1978). Metabolic rate may be limited by the energy-supplying capacity of the circulatory network (West et al, 1997).…”

Section: Discussionmentioning

confidence: 98%

Functional Trade-Offs in White Matter Axonal Scaling

et al. 2008

View full text Add to dashboard Cite

The brains of large mammals have lower rates of metabolism than those of small mammals, but the functional consequences of this scaling are not well understood. An attractive target for analysis is axons, whose size, speed and energy consumption are straightforwardly related. Here we show that from shrews to whales, the composition of white matter shifts from compact, slow-conducting, and energetically expensive unmyelinated axons to large, fast-conducting, and energetically inexpensive myelinated axons. The fastest axons have conduction times of 1-5 ms across the neocortex and Ͻ1 ms from the eye to the brain, suggesting that in select sets of communicating fibers, large brains reduce transmission delays and metabolic firing costs at the expense of increased volume. Delays and potential imprecision in cross-brain conduction times are especially great in unmyelinated axons, which may transmit information via firing rate rather than precise spike timing. In neocortex, axon size distributions can account for the scaling of per-volume metabolic rate and suggest a maximum supportable firing rate, averaged across all axons, of 7 Ϯ 2 Hz. Axon size distributions also account for the scaling of white matter volume with respect to brain size. The heterogeneous white matter composition found in large brains thus reflects a metabolically constrained trade-off that reduces both volume and conduction time.

show abstract

“…The range of observed values is approximately 1.2-fold in mouse [Nowaczyk and Des Rosiers, 1981], in rat [Sokoloff et al, 1977;Collins et al, 1987], and in macaque [Kennedy et al, 1978;Shapiro et al, 1978]. In addition, brain metabolic rates are also remarkably independent of waking or cognitive state [reviewed in Sokoloff, 1996].…”

Section: Tradeoffs In a Mixed Axon Population: Neocortical White Mattermentioning

confidence: 99%

Functional Tradeoffs in Axonal Scaling: Implications for Brain Function

Wang

2008

Brain Behav Evol

View full text Add to dashboard Cite

Like electrical wires, axons carry signals from place to place. However, unlike wires, because of the electrochemical mechanisms for generating and propagating action potentials, the performance of an axon is strongly linked to the costs of its construction and operation. As a consequence, the architecture of brain wiring is biophysically constrained to trade off speed and energetic efficiency against volume. Because the biophysics of axonal conduction is well studied, this tradeoff is amenable to quantitative analysis. In this framework, an examination of axon tract composition can yield insights into neural circuit function in regard to energetics, processing speed, spike timing precision, and average rates of neural activity.

show abstract

Application of the 2-Deoxy-<i>D</i>-[<sup>14</sup>C]-Glucose Method to the Mouse for Measuring Local Cerebral Glucose Utilization

Cited by 9 publications

References 6 publications

Quantitative surface electromyography in anesthesia and critical care

Quantitative surface electromyography in anesthesia and critical care

Functional Trade-Offs in White Matter Axonal Scaling

Functional Tradeoffs in Axonal Scaling: Implications for Brain Function

Contact Info

Product

Resources

About