A method for evaluating behavioral activity in Rana pipiens induced by changes in illumination

The method involved: (a) using the change in level of illumination to determine the start of the time base; (b) recycling the illumination conditions with sessions; and, (c) averaging activity scores within corresponding minutes across cycles. Frogs were generally more active in the light than in the dark when subjected to sufficiently long light and dark periods; several minutes were required to stabilize the activity levels after illumination changes. The lateral eyes had to be functional for the animals to respond relatively rapidly to illumination changes while the lateral eyes were not essential for general activation in the presence of a changing illuminated environment.     

Recovery of weight regulation following ablation of frontal cortex in rats

Recovery of a postoperative weight loss following bilateral ablations of frontal cortex in rats was quicker when food pellets were scattered on the cage floor than when pellets were available only in attached food hoppers. Food deprivation prior to surgery facilitated recovery when food was scattered on the cage floor after surgery. Successive stage surgery also facilitated recovery. Despite and facilitative influences on recovery from the initial postoperative weight loss, all frontal rats showed a temporary weight loss 4–5 weeks after surgery if food previously available on the cage floor was removed (food remained in the hoppers). The results indicated that time per se after surgery and postoperative experience had different roles in recovery of function following brain damage.     

Effects of illumination on auditory threshold.

Auditory thresholds of four squirrel monkeys were examined with a 4 kHz tone in light and dark ambient sensory conditions. The results revealed that auditory sensitivity is higher in the light than in the dark.     

Stimulants and lesions of the substantia nigra and red nucleus

The interaction of altered activity levels by stimulants and brainstem lesions was examined. Lesions of the substantia nigra and red nucleus significantly increased activity over control levels in albino rats. The stimulant action of d-amphetamine and methylphenidate was additive with lesion effects. In addition, stimulants disrupted the normal light-dark relationship with activity while the lesions did not. It is suggested that there are two functionally separate systems regulating locomotor activity.     

The effects of frontal lesions on brain hypersynchronous bursting and behavioral activity

Photically evoked after-discharge (PhAD) bursting was examined in lightly restrained albino rats following frontal and mid-cortical lesions. The initial effect of dorsal frontal lesions was to significantly suppress PhAD occurrence. Spontaneous activity as measured on an open-field arena was examined as a second variable. Frontally lesioned animals were significantly more active than mid-cortically lesioned and non-lesioned control animals in the initial stages of behavioral testing. These results indicate that the frontal cortex has an inhibitory influence on reticular formation (rf) arousal mechanisms which are responsible for behavioral arousal and the modulation of hypersynchronous burst-like phenomena occurring at the level of the cortex.     

The role of asymmetrical frontal cortical activity in aggression

Aggression correlates with relatively greater left than right frontal electroencephalographic activity (inverse of EEG alpha power). The present experiment extends this research by manipulating frontal asymmetry and examining its effect on aggression. Participants were assigned to increase left frontal activation or increase right frontal activation by contracting their contralateral hand. They then received insulting feedback and played a game in which they could aggress toward the person who insulted them. Right-hand contractions caused greater left than right central and frontal activation and aggression as compared to left-hand contractions. Within the right-hand contraction condition, greater relative left frontal activity was associated with greater aggression.     

A comparison of frontal pole, anterior median and caudate nucleus lesions in the rat

Rats with frontal pole cortex, anterior median cortex, caudate nucleus or sham control lesions were tested on activity, spatial reversal learning and delayed response learning. Performance of the lesioned groups of rats was compared with that of higher mammals with frontal and caudate lesions on similar problems. Rats with either type of frontal lesion were significantly more hyperactive than controls during the first hour of testing but were not impaired on reversal or delayed response learning. Caudate lesioned rats were significantly more hyperactive than the frontally lesioned groups, were significantly impaired on the reversal task and showed some indication of impairment on the delayed response task.     

Recovery of feeding in rats following frontal neocortical ablations

This study examines behavioral recovery from the aphagia-adipsia syndrome following frontal neocortical ablation in relation to the recovery of neurological function in the brain-damaged animal. Regulation of food and water intake in the post recovery period was also investigated. Behavioral recovery occurs in three articulated stages of improving sensori-motor function which reflect the animal's underlying neurological recovery. The first stage is one in which food and water intake can be accomplished only by reflexive sucking. In the second stage, goal directed scraping of the surface of solid foods and ingestion of soft foods are possible. In the final stage, chewing and biting are re-established and normal weight regulation is maintained on a standard laboratory diet. After recovery, sensori-motor deficits remain which do not impair feeding and drinking unless mechanically difficult diets are presented. Except for a response deficit in the insulin-induced overeating test and an increased sensitivity to quinine adulterated food, recovered animals respond normally to a series of regulatory challenges.     

Effects of gaze on apparent visual responses of frontal cortex neurons

Previous reports have argued that single neurons in the ventral premotor cortex of rhesus monkeys (PMv, the ventrolateral part of Brodmann's area 6) typically show spatial response fields that are independent of gaze angle. We reinvestigated this issue for PMv and also explored the adjacent prearcuate cortex (PAv, areas 12 and 45). Two rhesus monkeys were operantly conditioned to press a switch and maintain fixation on a small visual stimulus (0.2° × 0.2°) while a second visual stimulus (1° × 1° or 2° × 2°) appeared at one of several possible locations on a video screen. When the second stimulus dimmed, after an unpredictable period of 0.4–1.2s, the monkey had to quickly release the switch to receive liquid reinforcement. By presenting stimuli at fixed screen locations and varying the location of the fixation point, we could determine whether single neurons encode stimulus location in absolute space or any other coordinate system independent of gaze. For the vast majority of neurons in both PMv (90%) and PAv (94%), the apparent response to a stimulus at a given screen location varied significantly and dramatically with gaze angle. Thus, we found little evidence for gaze-independent activity in either PMv or PAv neurons. The present result in frontal cortex resembles that in posterior parietal cortex, where both retinal image location and eye position affect responsiveness to visual stimuli.     

Dopamine and somatostatin modulated adenylate cyclase activity in the rat caudate-putamen following unilateral cortical ablation

Summary Dopamine and somatostatin-14 (SRIF) were incubated with a membrane fraction of rat caudate-putamen (CP) tissue in an adenylate cyclase assay in order to examine the D-1-receptor coupled adenylate cyclase activity 5 days and 3 weeks after unilateral ablation of the left frontal and lateral cortex. Five days after decortication the ipsilateral basal and dopamine stimulated adenylate cyclase activity was increased by about 30% compared to that of the contralateral side. Three weeks after decortication no significant difference could be seen. On either side basal and dopamine stimulated adenylate cyclase activity was not significantly decreased compared to sham operated controls. Somatostatin (10^-7 mol/l) reduced basal adenylate cyclase activity of the ipsilateral CP five days following lesioning and reduced the maximal stimulation induced by dopamine. The effects of somatostatin were most marked in the absence and at low concentrations of dopamine (10^-7–10^-6 mol/l). The effects of somatostatin in the lesioned CP were no longer apparent three weeks following surgery. These results do not favour a presynaptic localization of D-1-receptors on cortico-striate projection fibers and suggest that somatostatin is involved in the interaction of the cortico-striate and nigro-striatal projection systems and may play a role in the regulation of D-1-receptor linked adenylate cyclase.     

Constraints on task-based control of behaviour following frontal lobe damage: A single-case study

What factors determine stimulus-driven responses in patients with utilization behaviour? We examined this question by assessing the influence of an irrelevant cue on visual search in a patient showing evidence of utilization behaviour (F.K.), following bilateral damage to the medial frontal and temporal lobes. Despite being able to repeat the instructions, F.K. often responded to an item in the search display that matched the cue rather than the target. This effect was reduced under certain conditions: (a) when the cue–search interval increased, (b) when F.K. paid less attention to the cue, and (c) when the target discrimination task was made more difficult. On the other hand, the effect arose even when the cue was always invalid. We suggest that information from the cue competed with the top-down set to determine search. F.K.'s lesion makes it difficult for him to impose top-down knowledge rapidly, leading to responses automatically being based on attended, but irrelevant, cues under short cue–display intervals.     

An activity indicator of acute withdrawal depends on amphetamine dose in rats

A moderate dose of amphetamine (AMPH) produces hypoactivity around 20 h post-administration. This hypoactivity may be an indicator of an acute withdrawal state. The purpose was to see how AMPH doses affected the expression of this hypoactivity and, by inference, AMPH-induced acute withdrawal. Rats were housed in individual open fields, with free access to food and water. Light-dark cycles were scheduled such that drug-elicited patterns could be readily detected. Animals first received a series of eight control treatments, and then a series of 10 experimental treatments spaced at 33-h intervals. Different experimental treatment groups received saline, 1.0 mg/kg, 2.0 mg/kg, or 4.0 mg/kg AMPH. The effects of these treatments on 33-h patterns of locomotor activity were observed. Control treatments produced no systematic time-dependent changes in activity beyond the first hour post-treatment. All doses of AMPH produced typical short-term effects: They markedly increased locomotion and/or stereotypy during the first 3 to 6 h post-treatment. Acute and chronic administrations of the 2.0 and 4.0 mg/kg doses also produced similar changes in longer term activity patterns: They produced hypoactivity 20 h later, followed by a recovery of activity around hour 25 post-treatment. The timing of amphetamine-induced hypoactivity and acute withdrawal may be independent of dose over a wide range of doses. Time-dependent changes in AMPH-induced state may influence motivation and drug-related assessments. The methodology described here may provide an easy and rapid way to investigate the determinants of AMPH-induced hypoactivity and acute withdrawal.     

Circadian activity rhythms of the pig-tailed macaque,Macaca nemestrina,under constant illumination

Lcomotor activity was recorded in singly caged pig-tailed macaques Macaca nemestrina in constant conditions with intensities of illumination varying between 0.003 lux and 100 lux. Each animal was kept in at least 5 different conditions for 2–3 weeks each. Three quantities of the circadian rhythm: the period, the duration of activity as opposed to rest, and the amount of activity per period, could be shown to be positively correlated with light intensity. As in 6 other diurnal primate species, these findings contradict the so-called circadian rule according to which opposite correlations should exist between the circadian parameters and light intensity in diurnal and in nocturnal species of animals.     

Effects of bilateral frontal lesions on habituation of the head-shake response in the rat

This experiment investigated the effects of bilateral frontal cortical lesions on the frequency and shape of the habituation curve of the head-shake response, elicited by stimulating the ear with a stream of air, in the rat. The results from an initial procedural-control group indicated that the damage done to the ear by mounting the rats in a stereotaxic was sufficient to increase responding. The results from the basic experiment, using a before-after design, indicated that bilateral frontal cortical lesions led to an overall increase in responding but had no effect on the shape of the habituation curve over trials. The responding of control animals given bilateral cortical lesions in the occipito-parietal area had no effect on responding. The results suggest that the frontal cortex, at least in the rat, is not involved in habituation of all responses.     

Unilateral ablation of the frontal eye field of the rat affects the beating field of ocular nystagmus

Spontaneous saccadic orientation and compensatory eye movements in response to optokinetic and vestibular velocity steps were studied in head-restrained, pigmented rats before and 1–2 weeks after unilateral ablation of the frontal eye field (FEF). One group of rats (n=5) received a deep lesion and another group of rats (n=4) received a superficial lesion of the left FEF. Postoperative response parameters such as the duration of slow buildup of eye velocity, the steady state velocity gain, the duration of optokinetic afternystagmus and of per- and postrotatory vestibular nystagmus were similar in the two groups of rats and did not differ from preoperative values measured in the same individuals. Superimposed upon these velocity components of nystagmus was a transient orienting response that expressed itself by a shift of the beating field of nystagmus in quick phase direction (gaze shift). The amplitudes of this gaze shift in quick phase direction were asymmetric in rats with a deep FEF lesion. Gaze shift amplitudes toward the side of the lesion were significantly enhanced and gaze shift amplitudes toward the intact side were significantly reduced. Similar asymmetries were observed in the distribution of spontaneous orienting movements of these rats in the light. Spontaneous saccadic eye movements of the same animals in darkness, however, were symmetric in amplitude to either side. These deficits suggest a partial sensory hemineglect after a deep unilateral lesion of the FEF and an involvement of this structure in the selective attention for targets in visual space. Thus the FEF orients the gaze at rest by means of saccades toward points of interest and during simulated circular locomotion by means of a shift of the beating field of nystagmus toward the visual sector that will be approached next.     

Single unit activity in frontal cortex and caudate nucleus of young and old rats

Spontaneous neuronal activity was recorded extracellularly from isolated single units in frontal neocortex and caudate nucleus of young and aged F344 rats anesthetized with urethane. Average firing rates, mean interspike intervals (ISI)±standard deviations, and ISI frequency histograms were computed and analyzed by microprocessor. For frontal cortex cells (N=226), there was a nonsignificant trend toward slower average discharge rates in the old group. However, a significantly longer mean ISI and proportionally more very slow firing cells (<I Hz) were observed in old rats. A laminar analysis of frontal cortex unit activity in young animals showed average discharge rates to be distributed somewhat evenly throughout the cortical mantle with the exception of the zone 1200–1400 μ beneath brain surface. This depth corresponds approximately to layer V where a 50% increase in mean firing rate in young animals was observed. In aged animals, this increased cell firing in layer V was absent, while mean discharge rates in other laminae remained essentially the same in the young and old rat groups. Caudate nucleus cells (n=70) showed a significant shift towards fewer fast discharging cells in old rats, with the average firing rate diminished by one-third. Although more brain regions need to be examined in a similar fashion, the consistency of the present results with those previously reported for the brainstem and cerebellum suggests that slower firing rates and longer ISIs are likely to be wide-spread throughout the brains of aged rats.     

Single unit activity in the frontal eye fields of unanesthetized monkeys during eye and head movement

Summary Single unit activity in the frontal eye field was investigated in unanesthetized monkeys during eye and head movement. Two types of cells (I and II) were found. Type I fired during voluntary saccadic movement occuring in a given direction and also during the fast phase of optokinetic and vestibular nystagmus. Cells of this type were silent during smooth pursuit movement and the slow phase of nystagmus. It was found that the firing pattern of Type I cells was maintained irrespective of head movement.Type II cells fired during smooth pursuit eye movements and the slow phase of nystagmus; these units displayed a steady discharge when the eyes were oriented in a specific position. Also this type of cell maintained its characteristic discharge during head movement. A separate population of frontal eye field cells was found to be exclusively related to head turning.     

额叶癫痫发作的临床与脑电图特征

目的 :分析额叶癫发作的临床及EEG特征。方法 :经同步录像脑电图 (Video—EEG)监测 ,对 40例癫病人 181次额叶发作的临床表现及EEG进行同步分析。结果 :额叶发作频繁而短暂 ,以睡眠中发作为主。常见的临床表现依次为过度运动、扭转性强直、姿势性强直、发声、假性失神等。发作间期额区棘、尖波稀少且波形不典型 ,发作期额叶限局性或弥漫性的改变与背景活动的差别不明显。结论 :临床和EEG不典型是导致额叶发作临床诊断困难或误诊的主要原因。认识额叶发作的临床特点 ,延长EEG记录时间及发作期临床—EEG同步分析有助于对额叶发作的诊断。     

额叶癫癎发作的临床特征及脑电图分析

目的：探讨额叶癫癎发作的临床特征、脑电图（EEG）特点及临床意义.方法：回顾性分析30例经手术证实发作起源于额叶的药物难治性额叶癫癎患者87次临床发作症状、发作期及发作间期的头皮EEG特点.结果：额叶癫癎发作形式复杂多样,常见的发作形式有姿势性强直发作、过度运动性自动症、扭转性强直、阵挛性发作、发声、失神等,有时出现发作性情绪改变或自主神经症状等少见症状.额叶癫癎常见以下发作特点：发作频繁,常成簇出现,发作起止突然,持续时间短暂,发作后意识恢复快,以睡眠中发作为主.额叶癫癎发作间期EEG阳性率较低,额区棘波、尖波出现率相对较低,且波形不典型,发作期额叶限局性或弥漫性的改变与背景活动的差别不明显.结论：额叶癫癎临床和EEG不典型是导致额叶癫癎发作临床诊断困难的主要原因,认识额叶癫癎发作的临床特点,延长EEG记录时间,认真分析发作症候学、发作期同步EEG有助于明确诊断.