摘要:

When facing and evaluating the present state of the world, the brain generates predictions and expectancies together with some specific emotional state which imposes on any given situation – or rather on the individual relationship to that situation – its essential meaning that basically orients the choice of an appropriate behavioural strategy. This general notion is exemplified by concrete data concerning brain mechanisms which underlie aggressive behavi

ISSN:0006-8977    

DOI:10.1159/000115919

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Mesencephalic dopaminergic neurons appear to be involved in the organization of the behavioral response. They seem to facilitate the functioning of the integrative structures they innervate and to have a coordinated functioning, thus regulating the information transfer between these structures. In the present paper these two aspects have been investigated by behavioral and neurochemical approaches. Experimental studies were focused on the dopaminergic innervation of the nucleus accumbens.

ISSN:0006-8977    

DOI:10.1159/000115920

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

This paper reviews briefly a series of electrophysiological, neurochemical, and behavioural studies concerning the role by periventricular structures (periaqueductal gray and medial hypothalamus) in the generation of aversive affective states and in the organisation of overt escape behaviours.

ISSN:0006-8977    

DOI:10.1159/000115921

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

In the present study, illusory movements were used as a means of investigating certain sensorimotor interactions: it was proposed to describe the effects produced on the oculomotor system when muscular proprioceptive afferents in the arm were artificially activated by tendon vibration. The gaze displacements induced by these vibratory stimuli were analyzed in terms of the instructions to subjects (i.e., ''simple fixation'', allowing the possibility of ocular tracking, or ''obligatory fixation'', not allowing any eye movements) and the points in space on which the subject’s gaze was required to be fixed (on the hand or elsewhere). The results show that, whatever the experimental conditions applied, the oculomotor system always reacted to vibratory stimulation of proprioceptive afferents, even though no corresponding visual stimulus was presen

ISSN:0006-8977    

DOI:10.1159/000115922

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Unilateral injections of 6-hydroxydopamine into the substantia nigra of monkeys disrupted the initiation of learned movements performed with the contralateral forelimb. Failure to respond was observed in two types of behavioral tasks. The one involved a hand movement directed towards a target and the other, hand withdrawal without any spatial requirements at the end of the movement. The results suggest that the ability to perform the required response was recovered more quickly in the case of the task involving visually controlled movement.

ISSN:0006-8977    

DOI:10.1159/000115923

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Tapping responses were recorded in a group of patients who sustained lesions from cerebrovascular accidents and from an age-matched group of healthy subjects. In each experiment the stimuli were an auditory signal, a flash, or a light touch on the arm, delivered either at random intervals or at fixed time intervals of 1, 2, 3, or 4 s. The tapping response was done with each hand separately (first experiment) or with each hand alternately (second experiment). Healthy subjects, ''predicted'' the stimuli (response time less than 150 ms), when the ''preferred'' fixed time interval was used. One group of patients (n = 3), did not predict the stimuli at the preferred fixed intervals when tapping was done with the hand related to the involved hemisphere. The second group of patients (n = 3) did not predict the stimuli when tapping was done with either hand.

ISSN:0006-8977    

DOI:10.1159/000115924

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

A mathematical model of eye tracking of periodic square wave target motion has previously been proposed. In this work the model was further studied with regard to saccadic response time to symmetrical square wave target motionin 6 patients with unilateral parietal lesions following cerebrovascular accidents. Three types of saccadic response time were noted. In patients with type I, saccades contralateral to the damaged hemisphere had similar characteristics to those found in ipsilateral direction, but with longer response time. In those with type II, the saccadic response time was about the same on movement in either direction for repetitive target cycle durations of 1.2 or 2.0 s. In patients with type III, the target motion could not be predicted, in either direction.

ISSN:0006-8977    

DOI:10.1159/000115925

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Unilateral lesions of the substantia nigra were performed on baboons which had been previously trained to perform a visual pointing movement. The resulting motor impairment consisted of an increase in movement duration. This bradykinesia shows as a regular decrease in velocity. A possible change in mode of motor control caused by lesion of the SN is discussed. Partial exclusion of SN might bring about a shift from the feedforward to a feedback mode relaying more heavily on visual cues.

ISSN:0006-8977    

DOI:10.1159/000115926

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

It is argued that the premotor cortex plays a crucial role in the retrieval of movement. Monkeys with bilateral lesions in premotor cortex were found to be impaired at selecting between two movements on the basis of visual cues. This was true whether the visual cue was present at the time of response or was no longer visible. Yet other monkeys with bilateral lesions in dorsal premotor cortex had little difficulty in remembering a movement if they had just been forced to make it a few seconds earlier. It is suggested that the premotor cortex is involved in the process of translation from a visual or auditory cue to an associated movement.

ISSN:0006-8977    

DOI:10.1159/000115927

出版商:S. Karger AG    

年代:1989

数据来源: Karger