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The elevated plus maze test in mice-difficulties and solutions
238
Poster presentations sessions 1,2,3 / International Journal of Psychophysiology 69 (2008) 207–241
mobilized to perform various cognitive tasks. The ERPs components studied appear to be sensitive indices for the quantitative assessment of the AD patients' functional status.
doi:10.1016/j.ijpsycho.2008.05.113
Does age influence the effects of emotional pictures in an auditory CNV task? Zs.A. Gaal, R. Boha, M. Molnar Institute for Psychology, Hungarian Academy of Sciences, Psychophysiology Department, Budapest, Hungary Recent studies show a positivity bias in the elderly: they attend more to positive information than to negative, which is manifested in cognitive processing also, including memory, attention, decision making and language. Although it is an important and interesting question, there are only few electrophysiological studies in this field. In our experiment the effects of emotional pictures in an auditory CNV task were investigated in a young (MA = 21.14 ± 2.27 yrs, n = 22) and an old (MA = 66.48 ± 4.00 yrs, n = 21) group. In the control situation pairs of tones (ISI = 3000 ms, ν = 1000 Hz or 1200 Hz) were presented and the subjects had no task. In the task condition the participants had to press the right button on the joystick when the two tones were similar (40%), and press the left button, when they were different (60%). In 40% of the cases a picture (neutral, positive or negative valence, International Affective Picture System) appeared on the screen 1500 ms before the first tone, and it remained for 6.5 s. Visual (P1, N1, P2, N2, P3) and auditory (N2, P3) evoked potentials (EPs) and the contingent negative variations (CNV) were analyzed. Late visual EPs were affected by age, but the content of the pictures did not influence them. The amplitude of the CNV decreased with age, and it was smaller when a picture was presented, but their valence did not cause any differences. Age had an effect only on the amplitude of the second tone evoked N2 and P3. The amplitude of these components increased when a picture was presented. In sum, age influenced the EPs, but there was no difference in the effects of emotional pictures across the age groups.
doi:10.1016/j.ijpsycho.2008.05.114
The processing of suprasegmental cues is speech specific as evidenced by ERPS F. Honbolygo, V. Csepe Hungarian Academy of Sciences, Research Institute for Psychology, Budapest, Hungary We present the results of a series of experiments investigating the processing of suprasegmental speech cues. In spite of the fact that the acousticphonetic information available in speech input is provided both by segmental and suprasegmental cues, we know far less about the processing of the later than about the well-studied segmental properties. One of the suprasegmental cues, the word stress is of particular importance, as it plays a crucial role in segmenting the speech stream and subserving lexical access. The aim of the study was to shed light on the processing characteristics of stress pattern, assumed to depend on a) the intelligibility of the word (word vs. non-word) and b) the speech-likeness of the word (speech vs. non-speech stimuli), by using the method of event-related brain potentials (ERP). Using a passive oddball paradigm we contrasted two words differing in their stress pattern (stress on the first syllable vs. stress on the second syllable, the later is not viable in Hungarian) in three different conditions. In Condition 1, we used a meaningful Hungarian word (‘banán’, meaning ‘banana’ in English), in Condition 2, we used a meaningless word (‘bebe’) and in Condition 3, we used the low-pass filtered version of the stimuli applied in condition 1. Low-pass filtering renders speech stimuli unintelligible, but keeps the suprasegmental information intact. The word with stress on the first syllable served always as standard, and the word with stress on the second syllable served as deviant. As a result, we obtained a complex of mismatch negativity (MMN) components in two of the three conditions. The deviant stimulus in Conditions 1
and 2 elicited two MMNs: one as a response to the lack of stress as compared to the standard stimulus, and another to the additional stress. However, the first MMN was missing in Condition 3. We interpret this finding as a possible brain correlate of crucial differences between the two processes: rule and regularity-based for speech uninfluenced by lexicality, and only regularitybased for non-speech. This means that the processing of word and word-like stimuli is governed by both salient acoustic features and rule applications, leading to strong expectations about the place of stress. However, these expectations are speech-specific, as they do not seem to operate for words loosing their “speechness” via low-pass filtering, as indicated by the ERP pattern differing from those elicited by words or non-words (missing first MMN).
doi:10.1016/j.ijpsycho.2008.05.115
The elevated plus maze test in mice-difficulties and solutions N. Sziray, G. Gigler, G. Levay, L.G. Harsing Jr., I. Gacsalyi EGIS Pharmaceuticals Plc. Budapest, Hungary Elevated plus maze test (EPM) is one of the most widely used animal models for screening anxiolytic and anxiogenic agents. It is an exploratorybased approach–avoidance paradigm measuring non-conditioned responses. Its simplicity and relatively low cost made it essential in the preclinical phase of industrial research for central nervous system drugs. However, it has its well known shortcomings as numerous variables in test conditions are known to influence maze results, and interpretation of various animal behavioral patterns are still under debate in the literature. Recently we experienced disadvantageous changes in control and reference data of spatiotemporal parameters of EPM as a result of switching from manual to automatic assessment of the test, and also of seasonal instability. Control data significantly increased, whereas the reference compound Diazepam (3 mg/kg, intraperitoneally) did not produce stable significant anxiolytic effects but caused nearly 50% of the animals to fall from the maze. This study reports the results of the numerous attempts performed to solve these difficulties. The methodological basis for EPM was the work of Lister (1987). To detect anxiety or anxiolytic-like efficacy, time spent in open arms (open time, OT) and entries to open arms (open entries, OE) were the parameters used. Significant increases compared to control data of one or both parameters was considered as an anxiolytic-like effect. For automatic assessment TSE VideoMot2 software was used. The following amendments of EPM paradigm were made: maze-related: adjusting rim, changing length/width/illumination of arms, and location of maze. Animal-related: changing source/diurnal cycle/foraging and handling regime/test-ambience pre-exposure of mice. Protocol-related: changing testperiod interval. Only few of these alterations exerted positive influence on data: using mice with normal instead of reversed circadian rhythm and 1 day fooddeprivation before conducting EPM resulted in stable anxiolytic-like effect of Diazepam. 8 day-long pre-exposure of mice to testing ambience and local illumination of open arms instead of diffuse illumination of whole maze both resulted in robust, statistically significant decrease of OT (97.4 ± 7.8 for diffuse and 54.7 ± 4.3 for local mean ± SEM; p b 0.001) and OE (14.2 ± 1.0 for diffuse and 4.8 ± 0.3 for local mean ± SEM; p b 0.001) control data. Our results indicate that maze-illumination and pretest schedule of animals has a crucial impact on EPM data probably by increasing anxiety of mice before testing and by augmenting absorption of test compounds, whereas alterations of maze-parameters and location have no major effect.
doi:10.1016/j.ijpsycho.2008.05.116
The brain as a dynamical network: Inferring interactions between its units O. De Feo Universtity College Cork, Department of Microelectronic Engineering, Cork, Ireland The measurable electrophysiological activity of the brain, together with its relation to the underlying neuronal networks activity and to the perceptuo-
Poster presentations sessions 1,2,3 / International Journal of Psychophysiology 69 (2008) 207–241
mobilized to perform various cognitive tasks. The ERPs components studied appear to be sensitive indices for the quantitative assessment of the AD patients' functional status.
doi:10.1016/j.ijpsycho.2008.05.113
Does age influence the effects of emotional pictures in an auditory CNV task? Zs.A. Gaal, R. Boha, M. Molnar Institute for Psychology, Hungarian Academy of Sciences, Psychophysiology Department, Budapest, Hungary Recent studies show a positivity bias in the elderly: they attend more to positive information than to negative, which is manifested in cognitive processing also, including memory, attention, decision making and language. Although it is an important and interesting question, there are only few electrophysiological studies in this field. In our experiment the effects of emotional pictures in an auditory CNV task were investigated in a young (MA = 21.14 ± 2.27 yrs, n = 22) and an old (MA = 66.48 ± 4.00 yrs, n = 21) group. In the control situation pairs of tones (ISI = 3000 ms, ν = 1000 Hz or 1200 Hz) were presented and the subjects had no task. In the task condition the participants had to press the right button on the joystick when the two tones were similar (40%), and press the left button, when they were different (60%). In 40% of the cases a picture (neutral, positive or negative valence, International Affective Picture System) appeared on the screen 1500 ms before the first tone, and it remained for 6.5 s. Visual (P1, N1, P2, N2, P3) and auditory (N2, P3) evoked potentials (EPs) and the contingent negative variations (CNV) were analyzed. Late visual EPs were affected by age, but the content of the pictures did not influence them. The amplitude of the CNV decreased with age, and it was smaller when a picture was presented, but their valence did not cause any differences. Age had an effect only on the amplitude of the second tone evoked N2 and P3. The amplitude of these components increased when a picture was presented. In sum, age influenced the EPs, but there was no difference in the effects of emotional pictures across the age groups.
doi:10.1016/j.ijpsycho.2008.05.114
The processing of suprasegmental cues is speech specific as evidenced by ERPS F. Honbolygo, V. Csepe Hungarian Academy of Sciences, Research Institute for Psychology, Budapest, Hungary We present the results of a series of experiments investigating the processing of suprasegmental speech cues. In spite of the fact that the acousticphonetic information available in speech input is provided both by segmental and suprasegmental cues, we know far less about the processing of the later than about the well-studied segmental properties. One of the suprasegmental cues, the word stress is of particular importance, as it plays a crucial role in segmenting the speech stream and subserving lexical access. The aim of the study was to shed light on the processing characteristics of stress pattern, assumed to depend on a) the intelligibility of the word (word vs. non-word) and b) the speech-likeness of the word (speech vs. non-speech stimuli), by using the method of event-related brain potentials (ERP). Using a passive oddball paradigm we contrasted two words differing in their stress pattern (stress on the first syllable vs. stress on the second syllable, the later is not viable in Hungarian) in three different conditions. In Condition 1, we used a meaningful Hungarian word (‘banán’, meaning ‘banana’ in English), in Condition 2, we used a meaningless word (‘bebe’) and in Condition 3, we used the low-pass filtered version of the stimuli applied in condition 1. Low-pass filtering renders speech stimuli unintelligible, but keeps the suprasegmental information intact. The word with stress on the first syllable served always as standard, and the word with stress on the second syllable served as deviant. As a result, we obtained a complex of mismatch negativity (MMN) components in two of the three conditions. The deviant stimulus in Conditions 1
and 2 elicited two MMNs: one as a response to the lack of stress as compared to the standard stimulus, and another to the additional stress. However, the first MMN was missing in Condition 3. We interpret this finding as a possible brain correlate of crucial differences between the two processes: rule and regularity-based for speech uninfluenced by lexicality, and only regularitybased for non-speech. This means that the processing of word and word-like stimuli is governed by both salient acoustic features and rule applications, leading to strong expectations about the place of stress. However, these expectations are speech-specific, as they do not seem to operate for words loosing their “speechness” via low-pass filtering, as indicated by the ERP pattern differing from those elicited by words or non-words (missing first MMN).
doi:10.1016/j.ijpsycho.2008.05.115
The elevated plus maze test in mice-difficulties and solutions N. Sziray, G. Gigler, G. Levay, L.G. Harsing Jr., I. Gacsalyi EGIS Pharmaceuticals Plc. Budapest, Hungary Elevated plus maze test (EPM) is one of the most widely used animal models for screening anxiolytic and anxiogenic agents. It is an exploratorybased approach–avoidance paradigm measuring non-conditioned responses. Its simplicity and relatively low cost made it essential in the preclinical phase of industrial research for central nervous system drugs. However, it has its well known shortcomings as numerous variables in test conditions are known to influence maze results, and interpretation of various animal behavioral patterns are still under debate in the literature. Recently we experienced disadvantageous changes in control and reference data of spatiotemporal parameters of EPM as a result of switching from manual to automatic assessment of the test, and also of seasonal instability. Control data significantly increased, whereas the reference compound Diazepam (3 mg/kg, intraperitoneally) did not produce stable significant anxiolytic effects but caused nearly 50% of the animals to fall from the maze. This study reports the results of the numerous attempts performed to solve these difficulties. The methodological basis for EPM was the work of Lister (1987). To detect anxiety or anxiolytic-like efficacy, time spent in open arms (open time, OT) and entries to open arms (open entries, OE) were the parameters used. Significant increases compared to control data of one or both parameters was considered as an anxiolytic-like effect. For automatic assessment TSE VideoMot2 software was used. The following amendments of EPM paradigm were made: maze-related: adjusting rim, changing length/width/illumination of arms, and location of maze. Animal-related: changing source/diurnal cycle/foraging and handling regime/test-ambience pre-exposure of mice. Protocol-related: changing testperiod interval. Only few of these alterations exerted positive influence on data: using mice with normal instead of reversed circadian rhythm and 1 day fooddeprivation before conducting EPM resulted in stable anxiolytic-like effect of Diazepam. 8 day-long pre-exposure of mice to testing ambience and local illumination of open arms instead of diffuse illumination of whole maze both resulted in robust, statistically significant decrease of OT (97.4 ± 7.8 for diffuse and 54.7 ± 4.3 for local mean ± SEM; p b 0.001) and OE (14.2 ± 1.0 for diffuse and 4.8 ± 0.3 for local mean ± SEM; p b 0.001) control data. Our results indicate that maze-illumination and pretest schedule of animals has a crucial impact on EPM data probably by increasing anxiety of mice before testing and by augmenting absorption of test compounds, whereas alterations of maze-parameters and location have no major effect.
doi:10.1016/j.ijpsycho.2008.05.116
The brain as a dynamical network: Inferring interactions between its units O. De Feo Universtity College Cork, Department of Microelectronic Engineering, Cork, Ireland The measurable electrophysiological activity of the brain, together with its relation to the underlying neuronal networks activity and to the perceptuo-