Bilateral Frontal Lesions Research Articles

Corpus callosum section for patients with intractable epilepsy.

Microsurgical techniques of callosotomy were effective in relieving medically intractable epilepsy in 14 of 16 patients. Intra-arterial digital angiography has been used preoperatively to assess drainage of the veins of the frontal lobe. MRI is useful in verifying the postoperative extent of corpus callosum section. Patients with bilateral frontal lesions and unilateral destructive lesions responded to callosotomy. None of the patients had an increase in seizures after the procedure.

Semantic encoding deficits in frontal lobe disease and amnesia

The relationship between semantic encoding deficits and memory dysfunction was evaluated for the following groups: (1) amnesic patients with bilateral frontal lobe lesions; (2) nonamnesic patients with bilateral frontal lesions; and (3) alcoholic Korsakoff patients. Semantic encoding was assessed using the Wickens' release from proactive interference (PI) paradigm. Korsakoff patients and the poor memory frontal lobe patients failed to show automatic PI release, while good memory frontal patients did show a release. These results support the view that an encoding disability is a contributor to amnesics' memory disorder and they suggest a possible neuroanatomical correlate for impaired semantic encoding.

Development of speech and language following bilateral frontal lesions

Language and speech were studied in a young child with perinatally acquired bifrontal lesions. Bilateral frontal pathology seriously interfered with the development of intelligible speech and resulted in a persistent expressive aphasia. Analysis of the neuropsychological profile indicated impairments in intelligence and language comprehension. These deficits, however, were considered secondary to the profound speech programming disorder. The findings indicate that, despite the plasticity of the immature central nervous system, bilateral frontal injury sustained at an early age precludes the development of intelligible speech. Furthermore, structurally intact cortical regions outside the territories of the speech zones fail to mediate normal speech and language development.

Perception and memory of facial affect following brain injury.

Brain-lesioned patients and controls were shown a series of happy, sad, fearful, and angry faces and asked to identify verbally the facial emotion and later freely recall the affect when shown some of the faces having neutral expressions. Greater misperception of facial affect was associated with posterior lesions when bilateral lesions were removed from data analysis. Unilateral and bilateral frontal lesions, however, were associated with memory deficits for facial affect. As a group, right versus left hemisphere-lesioned patients were not different from each other in the perception or memory of facial affect. Right frontal lesions, however, seemed especially to disrupt recall of facial emotion.

Lateralized effects of bilateral frontal cortex lesions in rats

The effects of bilateral frontal cortical lesions on spontaneous diurnal rotation and locomotor activity were studied in female Sprague-Dawley rats and determined to be a function of preoperative directional bias. Such lesions decreased rotation and activity in rats with right-sided biases and increased rotation and activity in rats with left-sided biases. It is suggested that frontal cortex normally modulates a dopaminergic nigrostriatal asymmetry and that an asymmetry and that an asymmetry in corticostriate function, possibly involving glutamate, underlies the observed effects.

Deficits in eye movements following frontal eye-field and superior colliculus ablations.

1. This study investigated the effects of frontal eye-field and superior colliculus ablations on fixation patterns and saccadic eye movements. Monkeys were trained to pick apple pieces out of a multiple-slotted apple board while their heads were fixed. Eye movement records were obtained using predominantly the implanted search-coil method. 2. Both unilateral and bilateral frontal eye-field lesions produced only temporary deficits in eye movements. Following surgery monkeys tended to neglect the contralateral peripheral visual field and made fewer saccades to peripheral targets. Recovery was virtually completed in 2-4 wk. 3. Superior colliculus ablation reduced fixation accuracy, saccade frequency, and saccade velocity. These deficits showed little recovery with time. 4. Paired frontal eye-field and superior colliculus lesions produced dramatic deficits in visually triggered eye movements. Animals could no longer fixate their eyes on visual targets with any degree of accuracy. The range of eye movements was greatly reduced, as was the frequency and velocity of saccades. These deficits showed little recovery with time. 5. These results suggest that visually triggered saccadic eye movements are controlled by two parallel channels, one involving the superior colliculus and the other the frontal eye field.

A comparison of the effects of medial frontal, dorsomedial thalamic, and combination lesions on discrimination and spontaneous alternation in the rat

Two experiments were conducted to investigate the hypothesis that the medial frontal cortex and dorsomedial thalamus constitute a neural system mediating a common set of behaviors. Rats with bilateral medial frontal lesions, unilateral medial frontal lesions, bilateral medial thalamic lesions, unilateral medial thalamic lesions, contralateral medial frontal and medial thalamic lesions, and sham operations were compared on spontaneous alternation and visual-tactile discrimination. Only rats with bilateral medial thalamic lesions were found to be deficient on the two tasks. Thus, while the present experiments are consistent with earlier work demonstrating that a functional medial thalamus is necessary for normal spontaneous alternation and discrimination, the present experiments failed to support the notion that the medial thalamus and medial frontal cortex constitute a common behavioral system.

Effects of caudate nuclei or frontal cortical ablations in kittens: Bar pressing performance

The bar pressing tasks which were used to test adult-operated cats were applied to juvenile and adult animals with bilateral caudate or frontal cortical lesions inflicted during the first month of life. Intact and sham-operated littermates served as controls. All three operated groups showed significantly slower rates of acquisition. Significantly fewer acaudate cats acquired the initial response, and only two each of the acaudates and afrontals reached the single alternation criterion. The acaudate cats, furthermore, showed significantly slower rates of transfer, overall responding, and alternation, but did not exhibit the postural adjustments seen in adult-operated animals and could bar press and drink simultaneously. There was a direct relationship between the magnitude of the deficit and the size of the caudate removal. The afrontals showed unsustained, erratic performances and were unmotivated and distractable. The data suggest that although there may be some savings in the more subtle nuances of behavior, the overall effects on bar pressing performance in the neonatally operated subjects can be just as great as when the lesions occurred later in life.

The effects of bilateral frontal eye-field lesions on the learning of a visual search task by rhesus monkeys

The effects of bilateral frontal eye-field lesions on the learning of a visual search task by rhesus monkeys

Control of thalamic transmission by corticofugal and ascending reticular pathways in the visual system.

Control of thalamic transmission by corticofugal and ascending reticular pathways in the visual system.

Tongue usage as a measure of cerebral cortical localization in the rat

Previous work has demonstrated that forelimb-digital usage is disrupted in rats with frontal cortical lesions. The present experiment indicates that other motor functions, specifically tongue usage, are also influenced by the rodent cerebral cortex. The observed deficits of tongue usage were related to frontal cortical lesion placement and thereby support recent electrophysiological mapping studies of the rodent motor and somatosensory cortex. Bilateral frontal cortical lesions which were placed in two operative stages with interoperative testing did not spare tongue usage.

Spatial orientation in man: effects of left, right, and bilateral posterior cerebral lesions.

Men with chronic, penetrating missile wounds of the brain were examined with two `spatial' tasks: a visually-guided stylus maze and a locomotor map-reading task. Men whose lesions involved the posterior part of the right cerebral hemisphere were significantly worse than those with left posterior lesions at stylus maze-learning. On the locomotor task, however, a highly significant deficit was found in the group of men with bilateral posterior cerebral lesions, while those with unilateral lesions of either hemisphere and those with bilateral frontal lesions were unimpaired. The contributions of the two cerebral hemispheres to the analysis of spatial information are discussed in the light of these results and it is suggested that, while the right hemisphere has a special role in the perception of space, it does not bear exclusive responsibility for the maintenance of spatial orientation.

Supranuclear paralysis of voluntary lid closure.

Two patients showed inability to voluntarily close the eyes. They had normal reflex closure and slept with their eyes closed. Comprehension was normal. Both had bilateral frontal lesions. This symptom is probably indicative of fundamental motor dysfunction, rather than apraxia as has previously been suggested.

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.

Enhanced amphetamine responses after frontal cortex lesions in the rat

The behavioural effects of amphetamine include stimulation of spontaneous motor activity and the elicitation of stereotyped behaviour. These drug effects are enhanced after bilateral frontal cortex lesions in the rat. It is suggested that the lesion alters the balanced control of motor output mediated by the basal ganglia and thereby the stimulatory effects of the neurotransmitter, dopamine, released by amphetamine from the corpus striatum.

Effects of combined frontal and temporal lesions on learned behaviors in rhesus monkeys.

Delayed response ability, and to a lesser extent visual discrimination performance, is seriously impaired by extensive bilateral damage to the frontal lobes. Reciprocal anatomical connections between the frontal and temporal lobes suggested that massive lesions in both lobes might produce an impairment more complete than that resulting from frontal lobectomy alone. Five monkeys were given combined bilateral frontal and anterior-temporal lesions, and were found to be inferior to both frontal lobectomized monkeys and to unoperated controls on the object discrimination task. The combined lesion did not increase the deficit on delayed response over that obtained after only bilateral frontal lobectomy. Results indicate that the anterior-temporal neocortex is involved in the mediation of visual discrimination ability.

Differential behavioral effects in frontal lobe disease

The performances of groups of patients with left, right and bilateral frontal lesions were compared on a battery consisting of two tests presumed to be related specifically to left hemisphere function, two tests presumed to be related specifically to right hemisphere function, and two tests presumed to be related specifically to bilateral frontal lobe function. Eighteen predictions, based on both theoretical considerations and the indications of previous literature, were made concerning the differences in performance to be expected among the three groups. Fifteen of the 18 predictions were confirmed by the results. It is concluded that some of the interhemispheric differences in performance which have been found in comparisons of patients with unilateral post-Rolandic lesions are also demonstrable in patients with unilateral frontal lesions and that certain task performances are particularly susceptible to the effects of bilateral frontal lobe damage.

Tactile learning and memory in baboons after temporal and frontal lesions

Three groups of baboons with different cortical lesions and an unoperated control group were studied on a series of tactile discrimination problems and day to day tactile memory tests. The animals with bilateral inferotemporal and bilateral inferotemporal plus medial temporal lesions were not impaired either on the initial discriminations or on the 24-hour retention tests, their performance being superior to that of the unoperated controls. Animals with bilateral frontal lesions, however, had considerable difficulty in learning and retaining the problems, an impairment which is interpreted in terms of perseverative tendencies.

Learning and memory in baboons with bilateral lesions of frontal or inferotemporal cortex.

A RECENT review of evidence for a “frontal lobe system”1 indicates that damage to lateral frontal cortex could interfere with mechanisms that contribute to the regulation of selective attention. Such evidence gives physiological foundation to Oxbury's “sensory disinhibition” hypothesis2. This suggests that the poor delayed response performance of sub-human primates with bilateral frontal lesions arises from the difficulty they find in limiting attention to the stimulus to be remembered rather than from impaired short-term storage3 or recall4.

Visually-guided maze learning in man: Effects of bilateral hippocampal, bilateral frontal, and unilateral cerebral lesions

Seventy-nine patients with different cerebral lesions were trained on a visually- guided stylus maze. The main findings were: (1) bilateral hippocampal lesions produced the most severe impairment, with one patient showing no progress in 215 trials; (2) right temporal lobectomy produced a significant deficit, particularly when the underlying hippocampus was radically excised, whereas patients with left temporal-lobe lesions of equal extent, or with small parietal-lobe lesions of either hemisphere, obtained normal scores; (3) larger lesions of frontal or right posterior cortex severely impaired maze learning, suggesting that size as well as locus of cortical lesion may be a factor in maze-performance; (4) only frontal-lobe lesions affected the ability to follow test instructions.