**Part 4**

**Medical Telemetry**

196 Modern Telemetry

Morin, L.P. (1994). The circadian visual system. *Brain Research*, Vol. 67, No. 1, pp. 102–127,

Morton, D.B., Hawkins, P., Bevan, R., Heath, K., Kirkwood, J., Pearce, P., Scott, L., Whelan, G.,

Muller, J.E., Tofler, G.H. & Stone, P.H. (1989). Circadian variation and triggers of onset of acute cardiovascular disease. *Circulation*, Vol. 79, No. 1, pp. 733–743, ISSN 0009-7322. Rusak, B. & Bina, K.G. (1990). Neurotransmitters in the mammalian circadian system. *Annual* 

Shaw, M.B., Herndon, C.D., Cain, M.P., Rink, R.C. & Kaefer, M. (2007). A porcine model of

Su, W., Guo, Z., Randall, D.C., Cassis, L., Brown, D.R., Gong, M.C. (2008). Hypertension and

Supowit, S.C., Rao, A., Bowers, M.C., Zhao, H., Fink, G., Steficek, B., Patel, P., Katki, K.A. & Dipette,

Van Vliet, B.N., Chafe, L.L., Antic, V., Schnyder-Candrian, S. & Montani, J.P. (2000). Direct and

Van Vliet, B.N., Chafe, L.L. & Montani, J.P. (2003). Characteristics of 24 h telemetered blood

Wessel, N., Malberg, H., Heringer-Walther, S., Schultheiss, H.P. & Walther, T.J. (2007). The

Xu, P., Costa-Goncalves, A.C., Todiras, M., Rabelo, L.A., Sampaio, W.O., Moura, M.M., Santos,

Zhang, B.L., Zannou, E. & Sannajust, F. (2000). Effects of photoperiod reduction on rat

Zimmerman, M.C., Lazartigues, E., Sharma, R.V. & Davisson, R.L. (2004). Hypertension

and kidney damage. *Hypertension*, Vol. 45, No. 1, pp. 109-1, ISSN 0194-911X. Van den Buuse, M. (1994). Circadian rhythms of blood pressure, heart rate, and locomotor

*Physiology & Behavior*, Vol. 55, No. 1, pp. 783–787, ISSN 0031-9384.

*Toxicological Methods*, Vol. 44, No. 2, pp. 361-73, ISSN 1056-8719.

549, No. 1, pp 313-25, ISSN 0022-3751.

Vol. 49, No. 2, pp 67-73, ISSN 0160-2446.

Vol. 51, No. 2, pp. 574-80, ISSN 0194-911X.

R169-78, ISSN 0363-6119.

bladder outlet obstruction incorporating radio-telemetered cystometry. *British Journal* 

disrupted blood pressure circadian rhythm in type 2 diabetic db/db mice. *American Journal of Physiology - Heart and Circulatory Physiology*, Vol. 295, No.4, pp. H1634-41,

D.J. (2005). Calcitonin gene-related peptide protects against hypertension-induced heart

activity in spontaneously hypertensive rats as measured with radio-telemetry.

indirect methods used to study arterial blood pressure. *Journal of Pharmacological and* 

pressure in eNOS-knockout and C57Bl/6J control mice. *The Journal of Physiology*, Vol.

angiotensin-(1-7) receptor agonist AVE0991 dominates the circadian rhythm and baroreflex in spontaneously hypertensive rats. *Journal of Cardiovascular Pharmacology*,

S.S., Luft, F.C., Bader, M., Gross, V., Alenina, N. & Santos, R.A. (2008). Endothelial dysfunction and elevated blood pressure in MAS gene-deleted mice. *Hypertension*,

circadian rhythms of BP, heart rate, and locomotor activity. *American Journal of Physiology - Regulatory, Integrative and Comparative Physiology*, Vol. 279, No. 1, pp.

caused by angiotensin II infusion involves increased superoxide production in the central nervous system. *Circulation Research*, Vol. 95, No. 2, pp. 210-6, ISSN 0009-7330.

*Laboratory Animals*, Vol. 37, No. 4, pp. 261-99, ISSN 0023-6772.

*Review of Neuroscience*, Vol. 13, No. 1, pp. 387–401, ISSN 0147-006X.

*of Urology International*, Vol. 100, No. 1, pp. 170-4, ISSN 2042-2997.

Webb, A., British Veterinary Association Animal Welfare Foundation, Fund for Replacement of Animals in Medical Experiments, Royal Society for the Prevention of Cruelty to Animals & Universities Federation for Animal Welfare. (2003). Refinements in telemetry procedures. Seventh report of the BVAAWF/FRAME/RSPCA/UFAW Joint Working Group on Refinement, Part A.

ISSN 0006-8993.

ISSN 0363-6135.

**10** 

**Use of Telemetric EEG in Brain Injury** 

Telemetry technology allows remote measurement and recording of signals such as biopotentials. This technology offers the advantage of long-term EEG recordings without causing unnecessary distress, as happens in EEG systems where implanted leads connect to the recording device through a cable. The EEG recordings can be used to detect changes in the brain activity after a traumatic event. The use of telemetry for EEG acquisition is the most reliable option in experimental studies due to the reduction of animal stress. Besides its current disadvantages, such as a reduced number of channels when compared to tethered EEG, telemetry can allow us to distinguish oscillatory brain patterns that become pathological after a neurological injury. Normal brain oscillatory synchronization can be correlated with cognitive function and behavioral state. However, abnormal brain oscillations can be caused by pathologies characterized by dysfunction of the cholinergic system and trauma, leading to epilepsy. This phenomenon is the result of abnormal hypersynchronous firing in certain neuronal populations in the brain. Although not all kinds of brain injury can induce epilepsy, the spike/wave activity present during epileptic seizures is of special relevance, because

The combination of EEG acquired through telemetry and video is widely used for assessment of epileptic focus, to distinguish epileptic seizures from psychogenic non-epileptic seizures, reassessment for potential surgery to treat epilepsy and to study animal models. Nevertheless, the assessment of the long-term EEG changes that occur after brain injury is a challenge, because a large amount of data is accumulated. Reducing the sampling rate and/or the recording schedule is not an option since each subject may respond differently to the injury and treatment. Furthermore, seizure-like events do not occur in pre-determined periods, therefore arbitrary sampling would compromise acquisition and analysis. In order to acquire reliable results, one requires a good estimation of duration and frequency of seizures and/or the duration of sleep stages. Several studies have addressed the need for analytical tools capable of optimally performing spectral analyses and, in this chapter, we evaluate the advantages and disadvantages of some available tools. The reduction and removal of artifacts in the acquired data, spectral decomposition of the signal using fast Fourier and wavelet transforms, and batch-processing will also be discussed. We will provide a view of the role of telemetric EEG technology in neuroscience, focusing on the study of brain injury induced by chemical means. Approaches to assess long-term EEG changes, choices of acquisition

**1. Introduction** 

severe brain injury can, in most cases, induce epilepsy.

parameters, and tools to analyze the EEG data will be introduced.

Marcio Furtado1, Franco Rossetti2 and Debra Yourick3

*1Clinical Research Management Inc.,* 

*Walter Reed Army Institute of Research* 

*3Science Education and Strategic Communications,* 

*2National Research Council,* 

*United States of America* 
