Proposal of conditional random inter-stimulus interval method for unconstrained enclosure based GPIAS measurement systems

Gap prepulse inhibition of acoustic startle (GPIAS) method has been used effectively for the objective assessment of tinnitus in animals. Among two types of enclosures for the GPIAS, the unconstrained type carries less risk of animal death due to the absence of binding stress in the enclosure, and lack of need for alteration to animal size variation as it grows. However, animals' voluntary movements, which have no relation to the startles evoked by acoustic stimuli, are problematic, as they cannot be excluded in the case of the unconstrained enclosure based GPIAS measurement system. In order to discount voluntary movements which are not associated with external acoustic stimuli, we propose the conditional random interstimulus interval (CR ISI) method for unconstrained enclosure based GPIAS measurement. With the proposed ISI method, the unconstrained enclosure based acoustic startle response measurement system has been implemented in this paper. As a result, the effectiveness of the proposed CR ISI method has been verified and compared with those of conventional ISI methods through animal experiments using SD-rats. The experimental results showed that abnormal startle responses and invalid GPIAS values caused by motion were prevented when our proposed CR ISI method was applied to our implemented system. It was also verified that our proposed CR ISI method is advantageous in reducing the total experimental time for acquiring normal startle responses and valid GPIAS values, compared to conventional ISI methods, since our proposed CR ISI can begin the acoustic stimulation only when the animal gets stable and motionless.

The establishment of positive and negative evaluative conditioning reflex of neutral facial expression / 中华行为医学与脑科学杂志

Objective To examine the effect of positive and negative evaluative conditioning (EC) on neutral faces.Methods The experiment consisted of three phases:baseline phase,conditioning phase,and re-evaluative phase,in which 41 college students participated,watching sequences of neutral faces (CS) pairing to either a positive stimulus (USpos) or a negative stimulus (USneg).Their emotional experiences (valence and arousal) and physiological reactivity (eyeblink startle reflex and skin conductance) were recor ded.Results (1) In the re-evaluative phase,CSpos was rated significantly more positive than CSneg and CSneut,while CSneg was rated significantly more negative than CSneut (CSpos (5.05± 1.24),CSneg (3.73± 1.48),CSneut (4.46± 1.04),P＜0.05).(2)In the re-evaluative phase,the mean startle eyeblink response magnitude(T score) to CSpos was significantly smaller than the responses elicited by CSneg and CSneut (CSpos (45.04±5.56),CSneg (51.44±9.30),CSneut (54.52± 10.60),P＜0.01).Conclusion The findings suggest that neutral faces can acquire valences and approach motivation through EC.

Modulation of the startle response in verbal aggressors: differences among stimuli with distinct affective social content

The emotional response to socially affective stimuli is an important variable to understand aggression. Research is lacking on the psychophysiological basis of verbal aggressiveness that would allow the identification of these emotional responses. The aim of the present study was to investigate modulation of the startle response in verbal aggressors during the presentation of visual stimuli with different affective social content. Acoustic startle probes were administered to 29 verbal aggressors and 28 non-verbal aggressors while viewing slides from the International Affective Picture System, which contains sexual, filial, neutral, unpleasant, and suffering of others pictures. Verbal aggressors showed a low startle response to sexual pictures compared with non-verbal aggressors and a potentiated startle response to neutral pictures compared with unpleasant, filial, and suffering of others pictures. These differences were observed among women. Based on previous studies, the present results may be explained by high testosterone levels, low cortisol levels, and moral disengagement exhibited by verbally aggressive women...

Sistema automático de análise comportamental em pombos / Automatic behavioral analysis system in pigeons

Este trabalho apresenta o projeto e os testes de um equipamento para registro automatizado da amplitude e da latência da resposta de sobressalto acústico em pombos. O sistema desenvolvido é formado por uma câmara experimental, com uma célula de carga acoplada ao piso para ser utilizada como sensor de força, circuitos para geração de estímulos (luz, som ou choque) e circuitos de condicionamento e interfaceamento dos sinais a um microcomputador utilizado para controle, armazenamento e análise dos dados. O software para controle do sistema foi desenvolvido utilizando-se linguagem C para operar em plataformas DOS ou Windows, com rotinas de controle para o protocolo experimental (número, duração e taxa de repetição dos estímulos) e rotinas gráficas para apresentar as curvas de amplitude da resposta em relação ao tempo, armazenamento dos dados no disco e processamento. Os dados são armazenados em arquivos e podem ser analisados estatisticamente com outros aplicativos computacionais. Foram realizados testes comportamentais com pombos e ratos, expostos a 20 estímulos sonoros (1 kHz, 100 dBA, duração de 1 s e taxa de repetição de 30 s). Os animais do grupo controle permaneceram na caixa durante 30 minutos sem receber estímulos. A amplitude do sobressalto, medida em kgf, foi registrada durante 4 s e analisada em janelas temporais de 1 s imediatamente após o som. Os testes com ratos apresentaram resultados semelhantes aos da literatura e indicaram a eficiência do sistema. Comparativamente aos ratos, os pombos apresentaram menor amplitude e maior latência e indicaram diferenças comportamentais entre as duas espécies. O equipamento mostrou-se adequado para as investigações neurobiológicas e comportamentais que usam modelos animais.

This work presents the design and testing of an apparatus for automatic recording of the magnitude and latency of acoustic startle response in pigeons. This system includes one experimental chamber with a load cell coupled to its floor (which is used as a force sensorto measure the amplitude of the response to the stimulus), stimuli generation circuits (light, sound or shock) and interfacing circuits (to a microcomputer that is used for control, storage and data analysis). The software used to control the system was developed using C language and runs under DOS or Windows operational systems. There are routines to implement the experimental protocol (number, duration and repetition rate of stimuli) and graphics routines to show the amplitude of the startle response curves as a function of time. The data may be saved in the disk for further statistical analysis with other programs. Behavioral tests with exposure to 20 tone-pulses (1 kHz, 100 dBA, 1 s, every 30 s) were carried out with pigeons and rats. The control group animals remained in the chamber during 30 min without receiving any acoustic stimulation. The magnitude of startle was recorded (in kgf) during 4 s andanalyzed in temporal windows of 1 s. The tests with rats corroborate the literature and indicate the efficiency of the system. Compared to rats, the pigeons presented lower magnitude and longer latency of acoustic response, indicating behavioral differences between the two species. The equipment was considered adequate for neurobiological and behavioral investigations which use automatic recording of acoustic stimuli responses.