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PubMed2002

Action sequencing deficit following frontal lobe lesion.

Frontal lobe patients carried out temporal sequencing tasks related to actions that differed in terms of their abstractness using both verbal and pictorial presentations. A generalized impairment was found: neither a type of action effect nor a modality of item presentation effect was present. The patients also carried out a corresponding action production task and produced actions quickly and without errors. The frontal lobe patients were also spared in generating verbal descriptions of actions: they were as accurate as normal controls both in terms of the details reported and in maintaining the temporal sequence. It has been argued that the difficulty in processing the temporal dimensions of actions following frontal lobe lesions is due to some form of disruption of the action representation. However, no action representational deficits were present in our frontal lobe patients. Thus, they cannot account for our findings. On the contrary, we suggest that the action sequencing deficit was a consequence of the difficulties patients experienced in rejecting wrong alternatives presented by the stimulus situation.

Activities of Daily Living↗
PubMed1985

The primate mediodorsal (MD) nucleus and its projection to the frontal lobe.

The frontal lobe projections of the mediodorsal (MD) nucleus of the thalamus were examined in rhesus monkey by transport of retrograde markers injected into one of nine cytoarchitectonic regions (Walker's areas 6, 8A, 9, 10, 11, 12, 13, 46, and Brodmann's area 4) located in the rostral third of the cerebrum. Each area of prefrontal, premotor, or motor cortex injected was found to receive a topographically unique thalamic input from clusters of cells in specific subdivisions within MD. All of the prefrontal areas examined also receive topographically organized inputs from other thalamic nuclei including, most prominently, the ventral anterior (VA) and medial pulvinar nuclei. Conversely, and in agreement with previous findings, MD projects to areas of the frontal lobe beyond the traditional borders of prefrontal cortex, such as the anterior cingulate and supplementary motor cortex. The topography of thalamocortical neurons revealed in coronal sections through VA, MD, and pulvinar is circumferential. In the medial part of MD, for example, thalamocortical neurons shift from a dorsal to a ventral position for cortical targets lying medial to lateral along the ventral surface of the lobe; neurons in the lateral MD move from a ventral to a dorsal position, for cortical areas situated lateral to medial on the convexity of the hemisphere. The aggregate evidence for topographic specificity is supported further by experiments in which different fluorescent dyes were placed in multiple areas of the frontal lobe in each of three cases. The results show that very few, if any, thalamic neurons project to more than one area of cortex. The widespread cortical targets of MD neurons together with evidence for multiple thalamic inputs to prefrontal areas support a revision of the classical hodological definition of prefrontal cortex as the exclusive cortical recipient of MD projections. Rather, the prefrontal cortex is defined by multiple specific relationships with the thalamus.

Animals↗
PubMed2006

Frontal lobe atrophy after prolonged frontal bone defect.

After a frontofacial monobloc in a 12-year-old Crouzon patient, the frontal bone was lost to infection. The patient did not attend postoperative appointments and was lost to follow-up. Nine years later, he reappeared requesting surgical reconstruction. This was performed satisfactorily with a titanium plate; however, it became apparent later that he had considerable atrophy of the frontal lobes and had developed the unstable behavior of patients who have undergone a frontal lobotomy. The atrophy would appear to be the consequence of the long-term absence of the frontal bones and the resultant repetitive frontal lobe microtrauma. Frontal infection and subsequent loss of the frontal bone is a recognized complication of monobloc advancement for faciocraniosynostosis and is mainly caused by the communication between the oronasal cavities and the cranial base. The frontal bone defect would normally be repaired after a delay of 6 months to a year with no significant sequelae. We present the unusual case of a patient whose frontal defect was not reconstructed for 9 years and who, as a result, developed frontal lobe atrophy and subsequent severe psychologic and behavioral difficulties.

Adult↗
PubMedDate not supplied

[Dementia with frontal lobe atrophy: clinical study from 18 patients with cognitive impairment and frontal lobe involvement detected by structural and functional neuroimaging].

OBJECTIVE: To characterize clinically patients with cognitive impairment and frontal lobe degeneration at neuroimaging. PATIENTS AND METHODS: Patients diagnosed of dementia or mild neurocognitive impairment by DSM IV criteria and neuropsychological tests with frontal lobe atrophy and hipoperfusion detected by computed tomography and single photon emission computed tomography. RESULTS: 18 patients, 5:1 on behalf of women; mean age at onset, 74 years; hereditary for dementia, 38%; mean duration of illness at first testing, 2 years; the most common initial symptoms, memory loss. At initial examination, psychotic or behavioral impairment was found in 61% and parkinsonism in 38%, the commonest cognitive troubles at this moment was the executive function, language and anterograde memory dysfunctions at the same rate. Frontal lobe atrophy and hypoperfusion was found in 100%, temporal in 88% and parietal in 38%. Electroencephalogram was pathological in 33%. The course of the disease was progressive but with fluctuation in 27%. Frontotemporal dementia clinical criteria in 13 patients, 4 of them clinical criteria of dementia with Lewy bodies too, and clinical criteria of Alzheimer s disease in 5.

Aged↗
PubMed2006

Medial versus lateral frontal lobe contributions to voluntary saccade control as revealed by the study of patients with frontal lobe degeneration.

Deficits in the ability to suppress automatic behaviors lead to impaired decision making, aberrant motor behavior, and impaired social function in humans with frontal lobe neurodegeneration. We have studied patients with different patterns of frontal lobe dysfunction resulting from frontotemporal lobar degeneration or Alzheimer's disease, investigating their ability to perform visually guided saccades and smooth pursuit eye movements and to suppress visually guided saccades on the antisaccade task. Patients with clinical syndromes associated with dorsal frontal lobe damage had normal visually guided saccades but were impaired relative to other patients and control subjects in smooth pursuit eye movements and on the antisaccade task. The percentage of correct antisaccade responses was correlated with neuropsychological measures of frontal lobe function and with estimates of frontal lobe gray matter volume based on analyses of structural magnetic resonance images. After controlling for age, gender, cognitive status, and potential interactions between disease group and oculomotor function, an unbiased voxel-based morphometric analysis identified the volume of a segment of the right frontal eye field (FEF) as positively correlated with antisaccade performance (less volume equaled lower percentage of correct responses) but not with either pursuit performance or antisaccade or visually guided saccade latency or gain. In contrast, the volume of the presupplementary motor area (pre-SMA) and a portion of the supplementary eye fields correlated with antisaccade latency (less volume equaled shorter latency) but not with the percentage of correct responses. These results suggest that integrity of the presupplementary motion area/supplementary eye fields is critical for supervisory processes that slow the onset of saccades, facilitating voluntary saccade targeting decisions that rely on the FEF.

Aged↗
PubMedDate not supplied

Functional activation of the frontal lobes. Regional cerebral blood flow findings in normals and in patients with frontal lobe dementia performing a word fluency test.

The present study examined the utility of the Word Fluency Test (WFT) as a frontal-lobe-activating test in brain imaging. Regional cerebral blood flow (rCBF) was measured during rest and during the WFT in 49 healthy volunteers and in 15 patients with frontal lobe dementia (FLD). The results showed a highly significant frontal lobe activation in 85% of the normal subjects. This finding was not related to age or to the level of performance on the WFT. A significant frontal activation was seen in 13 of the 15 FLD patients. The frontal flow increase did not reach normal levels, and was not related to age, illness duration or severity of clinical symptoms. The results suggest that the WFT is an ideal test to use in conjunction with functional imaging in normals as well as in patients with organic dementia.

Adult↗
PubMed2005

Catechol-O-methyl transferase Val158Met gene polymorphism in schizophrenia: working memory, frontal lobe MRI morphology and frontal cerebral blood flow.

The catechol-O-methyl transferase (COMT) gene is considered a leading schizophrenia candidate gene. Although its role in increasing schizophrenia susceptibility has been conflicting, recent studies suggest the valine allele may contribute to poor cognitive function in schizophrenia. V(158)M COMT genotype was obtained on 159 schizophrenia patients and 84 healthy controls. The effects of COMT genotype on four measures of working memory/executive functions (Wisconsin Card Sorting, digit span backward, Trail Making and N-back tests) and on MRI frontal brain volumes were examined. Genotype distributions were not significantly different between patients and controls. There were no significant genotype or genotype-by-group effects on any working memory/executive function measures. No genotype or genotype-by-diagnosis interaction effects were found with MRI frontal lobe volumes. Randomization analyses using [(15)O]H(2)O positron emission tomography (PET) cerebral blood flow data found Val/Val patients had higher frontal lobe activation than Met/Met patients while performing the one-back task. Overall, these findings do not support a major role for COMT in increasing susceptibility for schizophrenia or in mediating frontal lobe function. Age-related changes and phenotypic heterogeneity of schizophrenia may influence the complex relationships between COMT genotype and cognition.

Adult↗
PubMed1993

Topography of projections to the frontal lobe from the macaque frontal eye fields.

Efferents from the frontal eye fields (FEF) to the ipsilateral frontal lobe were studied by autoradiography of tritiated tracers (leucine, proline, and fucose) in seven macaque monkeys that were used previously to describe subcortical connections. In four of the cases, tracer injection sites were confirmed by low thresholds for the electrical elicitation of saccadic eye movements. Cases were grouped as lFEF of sFEF cases according to large or small saccades that were characteristic of the injection site. Projections from the FEF terminated in five frontal regions: 1) area FD on the dorsomedial convexity; 2) area FC (containing SEF) medial to the upper limb of the arcuate sulcus; 3) areas FD and FD delta along the walls of the principal sulcus; 4) area FCBm on the deep, posterior wall of the arcuate sulcus inferior to the sulcal spur; and 5) the inferolateral cortex (area FDi) on the convexity and lateral two thirds of the anterior wall of the arcuate sulcus. Projections in sFEF cases tended to be confined to medial parts of dorsomedial FD and FC and the lateral wall of the principal sulcus and inferolateral convexity. Neither lFEF nor sFEF appeared to project to the SMA or pericingulate cortex. Label in these areas was found only in the cases in which tracer spread into non-FEF areas. FEF projections terminated in column-like patches of about 500-600 microns in diameter. Labeled axons and terminals were seen in all cortical layers regardless of location in the frontal lobe.

Animals↗
PubMed1997

Rates of forgetting in organic amnesia following temporal lobe, diencephalic, or frontal lobe lesions.

Forgetting rates were examined in patients with diencephalic, temporal lobe, or frontal lesions. No significant differences were found in short-term forgetting of verbal and nonverbal material; in recognition memory for pictures, words, or designs over delays between 1 min and 20 or 30 min; or on a measure of explicit cued recall for words, calculated in terms of the process dissociation procedure. Significantly faster forgetting was found in the diencephalic and the temporal lobe groups in the free recall of pictures of objects, although there was no difference between these 2 groups. It is concluded that the major deficit in amnesic patients' memory processes is in the initial acquisition of information but that there is a subtler deficit in retention over specific delays, detectable only on measures of free recall.

Adolescent↗
PubMed2001

Frontal lobe functions.

The frontal lobes constitute two thirds of the human brain, yet the functions performed by them remained mysterious for a long time. Apart from their well-known involvement in motor function and language, little was previously known about the functions of the frontal lobes. Recent advances have uncovered important roles for the frontal lobes in a multitude of cognitive processes, such as executive function, attention, memory, and language. The importance of the frontal lobes in processes underlying affect, mood, personality, self-awareness, as well as social and moral reasoning, is also a renewed area for research. This article focuses on recent advances in understanding frontal lobe functions.

Cognition↗
PubMed2006

Nocturnal frontal lobe epilepsy.

Nocturnal frontal lobe epilepsy (NFLE) is a condition primarily characterized by seizures occurring exclusively or predominantly during sleep, the semiology of which suggest a frontal lobe origin and, more specifically, the involvement of the orbitofrontal or mesial frontal regions. It is usually considered as a relatively benign and homogeneous epileptic syndrome, the neuropsychological impact of which should be minimal. However, several issues complicate this view. 1. NFLE is rather a heterogeneous disorder which includes both sporadic and familial forms, various seizure types, and drug resistance in about 30% of patients. 2. The frontal origin of seizures has rarely been demonstrated, and mainly relies on the presence of ictal signs suggestive of frontal lobe epilepsy, but which might only reflect the propagation of ictal discharges of extrafrontal origin. 3. NFLE-like seizures were recently found to be associated with temporobasal cortical dysplasia, or an insular epileptogenic zone, including one patient with autosomal dominant frontal lobe epilepsy (ADNFLE). 4. No study has yet specifically evaluated the neuropsychological profile of patients with NFLE. Available data suggest that behavioral problems and mental retardation might be associated with ADNFLE, especially when it is related to a mutation of the nicotinic receptor subunits. Conversely, the majority of NFLE patients does not seem to present with gross cognitive disturbance, even though many of these patients complain of chronically disrupted sleep and daytime sleepiness. Further research is warranted in this field, keeping in mind that the neural networks underlying NFLE remain poorly known and might primarily involve extrafrontal brain regions in some patients.

Cerebral Cortex↗
PubMed1997

Autosomal dominant nocturnal frontal lobe epilepsy: demonstration of focal frontal onset and intrafamilial variation.

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is a newly recognized autosomal dominant partial epilepsy. We studied seizure localization and intrafamilial variation using video-EEG monitoring (VEM) and functional neuroimaging in two pairs of subjects from unrelated families. The clinical features of seizures were similar from seizure to seizure in each individual, but varied between individuals. As is often found in frontal lobe epilepsies, ictal EEG localization was imprecise in three of four cases. One patient showed a consistent left fronto-polar onset that was corroborated by congruent focal hypometabolism on interictal PET and focal hyperperfusion on ictal single photon emission computed tomography (SPECT). A second case studied with ictal SPECT showed a right parasagittal, midfrontal focus. We conclude that this autosomal dominant epilepsy syndrome, which in one of the two families was due to a known neuronal nicotinic acetylcholine receptor mutation, causes frontal lobe foci that are unilateral and in variable locations in different individuals.

Adolescent↗
PubMed2004

Frontal lobe epilepsy in childhood.

Frontal lobe epilepsy is poorly understood and often unrecognized by health care workers caring for children. We sought to better characterize frontal lobe epilepsy in childhood and help delineate this condition from other nonepileptic events. We reviewed pediatric patients admitted to the Comprehensive Epilepsy Program at the University of Alberta Hospitals with a proven diagnosis of frontal lobe epilepsy. Twenty-two patients, 13 males and 9 females, were studied. Age of onset was variable from 10 months to 16 years (mean 7.5 years). Seizures were brief (30 seconds to 2 minutes), stereotypic, nocturnal (17/21), and frequent (3-22/night). Clinical features included explosive onset, screaming, agitation, stiffening, kicking or bicycling of the legs, and incontinence. The diagnosis of frontal lobe epilepsy was not made in any child before referral. The referring diagnosis was sleep disturbance (10), psychiatric problems (6), or other seizure types (6). Interictal electroencephalogram was usually normal (18/21). Long-term video electroencephalographic monitoring demonstrated frontal (9) or bifrontal (13) epileptic discharges. Magnetic resonance imaging was normal in most patients (18/21). Seizure control was difficult, with only half (11/21) the patients being controlled on medication. Three intractable patients went on to epilepsy surgery and became seizure-free. Frontal lobe epilepsy in childhood is a distinct epilepsy syndrome with characteristic features. The seizures are brief, stereotypic, nocturnal, and frequent. Electroencephalogram and magnetic resonance imaging are usually normal. The condition is often misdiagnosed as a sleep disorder or psychiatric problem. Seizures are difficult to control but may respond to carbamazepine, valproic acid, or epilepsy surgery.

Adolescent↗
PubMed2002

Evidence for asymmetric frontal-lobe involvement in episodic memory from functional magnetic resonance imaging and patients with unilateral frontal-lobe excisions.

Recently, there has been considerable debate regarding the involvement of the left and right prefrontal cortices in the encoding and retrieval of episodic memory. In a previous PET study, we found that the use of easily verbalisable material may lead to activation predominantly in the left lateral frontal cortex whilst the use of non-easily verbalisable material may lead to activation predominantly in the right lateral frontal cortex, in both cases irrespective of encoding and retrieval processes. In order to replicate and extend these findings, the same task was modified for use with fMRI. Six healthy volunteers were scanned while encoding and then recalling stimuli that either emphasised visual or verbal processes. It was found that, in comparison to a baseline condition, the encoding of visual stimuli led to a bilateral activation of the prefrontal cortex whilst the encoding of verbal stimuli led to a preferential activation of the left prefrontal cortex. An effect of stimulus type was less evident during retrieval, with both visual and verbal stimuli leading to bilateral prefrontal cortex activation. Overall, encoding and retrieval activated similar regions of the prefrontal cortex suggesting that these areas mediate processes that are fundamental to both aspects of memory. To extend these findings further, the tasks used in the fMRI study were used to assess a group of patients with unilateral frontal lesions and a group of healthy control volunteers. The patients were significantly impaired compared to the healthy volunteers, although no significant differences were found in performance between the right- and left-sided lesioned patients. This result suggests that the memory-related asymmetries observed during functional neuroimaging studies may not be critical for task performance.

Female↗