294 Abstracts

Methods Male rats of the Wistar strain (purchased from Charles River,

Barcelona, Spain) weighing 220 – 250 g were used throughout all

experiments. For at least 1 week prior to experiments, the rats were

housed five to a cage at a constant temperature (20 – 23 �C), illumination

(12-h light/12-h dark cycle, light on at 08:00 h) and were provided with

food (Purine, Barcelona, Spain�) and water ad libitum. All animals

welfare and procedures were in accordance with the European Commu-

nities Council Directive of 24 November 1986 (86/609/ECC) and RD 223/

1988, and were approved by the University of Cordoba’s Bioethics

Committee, Spain.

To carry out this study, 25 rats were used. These rats were divided into five

groups as follows: i) control; ii) sham operated; iii) OBX; iv) OBX1mock;

and v) OBX 1 TMS. 24 h after last session of TMS and under anesthetic

with ether the animals were sacrificed by decapitation and their brain were

rapidly removed, frozen on dry ice, and stored frozen (-80 �C) until being

assayed.

LDH and caspase-3 were calculated by kits purchased by BioVision Inc.

(Mountain View, CA, USA), i.e., LDH-Cytotoxicity and Caspase-3/CPP32

colorimetric assays kit, respectively. SOD activity was calculated by

methods of Sun et al. (1988). The protein concentration was determined by

the Bradford method (1976) using kit purchased from Sigma Co. (St.

Louis, MO, USA), i.e., Bradford reagents B6916 assay kit.

Statistical analysis of the data was accomplished by means of the SPSS�statistical software package (SPSS Iberica, Madrid, Spain). To evaluate

variations in data, a one-way analysis of variance (one-way ANOVA) was

corrected with the Tukey test. The level of statistical significance was set at

P , 0.05.

Results: OBX significantly decreased SOD activity in brain tissue (P,

0.001), which was reverted by TMS (P, 0.001). LDH and caspase-3 were

used as an indicator of cell damage. Removal of olfactory bulbs in rats did

not affect LDH activity, whereas caspase-3 activity was significantly

enhanced (P , 0.001). The application of TMS reversed caspase-3 activa-

tion induced by OBX (P , 0.001).

Conclusion: our results suggest that: i) TMS present an antioxidative effect

in the OBX model of depression by stimulation of SOD; and ii) TMS

diminishes the activation of caspase-3.

Table Effect of Olfactory bulbectomy (OBX), and trascranial magnetic stimulation(TMS) on superoxide dismutase (SOD), lactate dehydrogenase (LDH) and caspase-3activities. n 5 5 animals per group. Data are represented means 6 SEM. a P , 0.001vs control and sham operated group; b P , 0.001 vs OBX.

Sham

Control operated OBX OBX+mock OBX + TMS

SOD(U/mgprotein)

40.406 1.14

40.406 1.34

22.20 6 0.84a

28.60 6 1.14 38.20 6 0.84b

LDH(IU/mL/mgprotein)

53.606 6.69

53.186 4.75

53.53 6 6.58

47.22 6 2.58 55.46 6 4.71

Caspase-3(OD arbitraryunits/mgprotein

0.266 0.010

0.266 0.011

0.37 6 0.011a

0.36 6 0.011 0.27 6 0.005b

tDCSPoster Only

173 Effect of transcranial direct current stimulation on single

motor unit responses to transcranial magnetic and electricalstimulation

Jaiser SR, Baker SN, Newcastle University (Newcastle upon Tyne, UK)

Objective: There has been a debate whether transcranial direct current

stimulation (tDCS) exerts its after-effects on corticospinal excitability by

synaptic or non-synaptic mechanisms. Whilst most electrophysiological

and pharmacological data support a synaptic mode of action, one previous

study demonstrated a significant effect of tDCS on motor potentials evoked

by transcranial electrical stimulation (TcES). As TcES is though to excite

corticospinal neurones directly, this would imply a non-synaptic effect of

tDCS.

Methods: To address this controversy, we recorded single motor unit

(SMU) responses to transcranial magnetic stimulation (TMS) and TcES of

the primary human motor cortex before and after 9 minutes of cathodal

tDCS (1mA). Recordings were made from the first dorsal interosseous

during isometric contraction, with subjects maintaining a steady SMU

discharge rate (6-12Hz) using visual and auditory feedback.

Results: The figure shows an example of the resulting peri-stimulus time

histograms (PSTHs). Before tDCS, TcES evoked a peak consistent with a

D wave, and TMS elicited peaks consistent with I waves. After tDCS, the

amplitude of the TcES-evoked D wave remained unchanged, whilst that of

the TMS-elicited I waves had significantly decreased.

Conclusion: These results support a synaptic mode of action of tDCS.

Movement DisordersPoster Only

174 Comparison of cortical excitability revealed by transcranial

magnetic stimulation and clinical characteristics inspinocerebellar ataxias type 1 and 2

Radovanovic S1, Dragasevic N2, Svetel M2, Kostic V2, 1Institute for

Medical Research (Belgrade, RS); 2Institute for Neurology, Medical

Faculty (Belgrade, RS)

Spinocerebellar ataxias are heterogeneous group of disorders characterized

by gait and limb ataxia variably associated with non-cerebellar signs

(pyramidal signs, occulomotor disturbances, polyneuropathy, dementia,

etc). They are characterized by underlying genetic defect (SCA types 1-

23). The clinical classification of the SCA has been difficult due to

variations and overlapping of the clinical signs.

The aim was to compare parameters of cortical excitability (cortical motor

evoked potential - MEP, central motor conduction time - CMCT, cortical

silent period - CSP duration) and clinical characteristics in groups of SCA

1 and 2 patients in population of Serbia.

We used TMS to examine 22 patients - 16 SCA1 and 6 SCA2. Twelve

healthy control subjects were gender and age matched. TMS was used to

investigate parameters such as: motor threshold (MT) and MEP, CSP and

CMCT. MT was established at rest, MEP was calculated as the area in the