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PubMed2004

Sequential memory: a developmental perspective on its relation to frontal lobe functioning.

The multidimensional nature of the frontal lobes serves to organize and coordinate brain functionings playing a central and pervasive role in human cognition. The executive processes implicated in complex cognition such as novel problem solving, modifying behavior as appropriate in response to changes in the environment, inhibiting prepotent or previous responses, and the implementation of schemas that organize behavior over time are believed to be mediated by the frontal regions of the brain. Overall, the functioning of the frontal lobes assists individuals in goal directed and self-regulatory behavior. Additional theories of frontal lobe functioning have focused on its involvement in temporal, or time-related domains. The organizational and strategic nature of frontal lobe functioning affects memory processes by enhancing the organization of to-be-remembered information. Among the specific memory systems presumed to be based on anterior cerebral structures is the temporal organization of memory. An essential component of memory that involves temporal organization is sequential ordering entailing the ability to judge which stimuli were seen most recently and the temporal ordering of events in memory. Focal lesion studies have demonstrated the importance of the frontal lobes on retrieval tasks in which monitoring, verification, and placement of information in temporal and spatial contexts of critical importance. Similarly, frontal lobe damage has been associated with deficits in memory for the temporal ordering, or sequencing, of events. The acquisition of abilities thought to be mediated by the frontal lobes, including sequential memory, unfolds throughout childhood, serving to condition patterns of behavior for the rest of the brain. Development of the frontal regions of the brain is known to continue through late adolescence and into early adulthood, in contrast to the earlier maturation of other cortical regions. The developmental patterns of the frontal lobes are thought to involve a hierarchical, dynamic, and multistage process.

Child↗

PubMed1999

Frontal lobe dysfunction in patients with non-frontal malignant gliomas: a monoaminergic dysregulation?

Previous investigations concerned with the neuropsychological function of patients with intracerebral supratentorial malignant gliomas has revealed the frequent occurrence of signs suggestive of an inhibitory frontal lobe dysfunction regardless of the intracerebral localization of the tumor and before the diagnosis was known to either the investigator or the patient. Upon closer analysis, the frontal lobe dysfunction has been verified by the demonstration of reduced blood flow in frontal areas in these patients. Since many of the findings can be related to a dysfunction of dopaminergic neurotransmission, we hypothesize that abnormal astrocytes interfere with the metabolism, transport and release of various neurotransmitters of which dopamine may be the one responsible for the most striking neuropsychological abnormalities in patients with malignant gliomas.

Animals↗

PubMed2001

The role of the frontal lobes in memory: evidence from unilateral frontal resections for relief of intractable epilepsy.

The current investigation explored processes associated with memory deficits in patients with frontal lobe dysfunction. Specifically, we examined deficits associated with the encoding, consolidation, and retrieval of information in memory in 53 patients who underwent either a unilateral frontal (N=13) or temporal (N=40) lobe resection for relief of intractable epilepsy. Post-surgical memory scores indicated that the frontal group and the temporal group did not differ in consolidation of information, as defined by the information forgotten between immediate and delayed recall. Instead, the temporal group evidenced significantly poorer recall of verbal information at both immediate and delayed recall. This effect was especially strong in the left temporal group for the recall of verbal information. Although no group differences were observed in the degree to which patients semantically organized information or made recency discriminations, the frontal group exhibited significantly weaker release from proactive interference than the temporal group, suggesting some impairment in encoding and retrieval processes associated with frontal lobe dysfunction.

Journal Article↗

PubMedDate not supplied

Role of the frontal lobes in the propagation of mesial temporal lobe seizures.

The depth ictal electroencephalographic (EEG) propagation sequence accompanying 78 complex partial seizures of mesial temporal origin was reviewed in 24 patients (15 from the University of Pittsburgh Epilepsy Center and 9 from UCLA). All patients were monitored with bilateral mesial frontal and mesial temporal depth electrodes and later received anterior temporal lobectomy. Ictal EEG records were categorized according to sequence of spread from the temporal focus to the other regions. Although propagation patterns varied both within and between patients, certain features were notable: (a) It was very common for seizure activity to spread initially to the ipsilateral frontal lobe (observed in 22 of 24 patients). (b) The most common mode of spread (15 of 24 patients) was initiating temporal lobe----ipsilateral frontal lobe----contralateral frontal lobe----contralateral temporal lobe. (c) Occasionally, seizure discharges invaded the frontal lobes but failed to invade the contralateral temporal lobe (2 of 24 patients). (d) Seizure activity occasionally invaded the contralateral temporal lobe prior to invading the frontal lobes (2 of 24 patients). Other notable features included (i) a clear tendency for mesial temporal seizure discharges initially to invade orbitofrontal (as opposed to anterior cingulate) cortex and (ii) the emergence of a period of clear asymmetry in the frontal lobes during which high-amplitude, rapid discharges were present on the side ipsilateral to the initiating temporal lobe. These results suggest that the prefrontal region, especially the orbitofrontal cortex, is strongly influenced by mesial temporal ictal activity. This region appears to be frequently involved in the propagation of seizures initiated in the mesial temporal lobe and may play a role in the interhemispheric propagation of mesial temporal seizures.

Brain Mapping↗

PubMed2002

Evidence for intact semantic representations in patients with frontal lobe lesions.

Patients with frontal lobe lesions and control participants were assessed on 2 tests of semantic knowledge. In the triadic comparison task, participants were shown all possible triplets of 12 animal names and judged which 2 of each triplet were most alike. In the ordered similarity task, participants rank ordered animals in terms of their similarity to a target animal. For both tasks, semantic structure--derived from multidimensional scaling techniques--revealed similar representations in patients with frontal lobe lesions and control participants. Additional pathfinder analyses also produced networks that did not differ between groups. These patients exhibited intact semantic knowledge despite deficits on tests of free recall and verbal fluency that involved the same semantic category and exemplars. Thus, intact representation of semantic knowledge in frontal patients stands in contrast to their marked deficits in strategic retrieval of semantic knowledge.

Adult↗

PubMed1992

Intact implicit memory in patients with frontal lobe lesions.

Patients with frontal lobe lesions and control subjects were administered tests of word-stem completion priming. In this implicit memory test, subjects are first presented words (e.g. MOTEL, PARADE) in an incidental learning paradigm. Following word presentation, subjects are shown word stems (e.g. MOT, PAR) and asked to produce the first word that comes to mind. Patients with frontal lobe lesions exhibited normal levels of word-stem completion. These findings indicate that implicit memory can operate normally despite damage to the prefrontal cortex. The present results substantiate previous neuropsychological and positron emission tomography findings which indicate that word priming depends critically on posterior cortical areas.

Brain Damage, Chronic↗

PubMed1998

EEG findings in frontal lobe epilepsies.

As a group, epilepsies of frontal lobe origin are thought to be poorly localized using surface EEG recordings. This finding may depend on the specific areas of frontal lobe from which the seizures originate or the pathologic substrate. We reviewed the presurgical surface EEGs of patients with frontal lobe epilepsy who underwent epilepsy surgery. The specific area of the frontal lobe where seizures originated was determined by 1) intracranial ictal EEG recordings, or 2) the presence of a structural lesion, identified by imaging studies in patients who achieved complete seizure control following surgery. We differentiated patients whose seizures began in the dorsolateral frontal convexity from those whose seizures began in the medial frontal region, and we correlated EEG findings in the interictal, postictal, and ictal states with seizure semiology, pathologic substrate, and surgical outcome. Four of nine patients had seizures originating in the dorsolateral frontal convexity and five had medial frontal onset seizures. Patients whose seizures originated from the dorsolateral convexity had focal interictal epileptiform abnormalities that localized to the region of seizure onset. Patients whose seizures began in the medial frontal region had either no interictal epileptiform abnormality or had multifocal epileptiform discharges. Patients whose seizures began in the dorsolateral convexity showed focal electrographic seizure activity that was localizing. This rhythmic fast activity did not appear to be substrate-specific. Patients whose seizure onset localized to the medial frontal region did not show focal electrographic seizure at clinical onset. We conclude that the scalp EEG recordings of frontal lobe epilepsies contain features that enable differentiation of seizures originating from two different regions of the frontal lobe.

Adolescent↗

PubMed2000

The Frontal Lobes, Epilepsy, and Behavior.

The frontal lobes have been overshadowed by the temporal lobes in the vast literature addressing the neurobehavioral and psychological perspectives of epilepsy. The purpose of this review is to summarize contemporary anatomicobehavioral correlations and to highlight the frontal lobe contributions to the neurology, neuropsychology, and neuropsychiatry of epilepsy, in general, and to temporal lobe epilepsy (TLE) and frontal lobe epilepsy (FLE), in particular. Much evidence has accumulated suggesting that focal epileptogenic tissue may have effects on distant neural systems. Data supporting the case that the frontal regions are preferentially affected in TLE are presented. Emphasis is placed on the results of numerous functional imaging studies demonstrating correlations between frontal hypoperfusion and cognitive or mood impairments in patients with TLE.

Journal Article↗

PubMed1983

[Regulation of pituitary gonadotropin release of the frontal lobe neocortex (1)].

It has been said that the frontal lobe neocortex regulates the secretion of pituitary hormones. In the present study, the nerve circuit including the frontal lobe neocortex which is concerned in regulating the secretion of pituitary gonadotropin was studied in the 4-day vaginal cycle of female Wistar rats. Electric stimulation (monophasic pulse wave, 1Hz, 6 approximately 9V) of the dorsal part of the anterior frontal lobe neocortex induced evoked potential in the thalamic dorsomedial nucleus (DM), the basolateral amygdaloid nucleus (basolateral-AMYG), the medial septal nucleus (m-SEPT) and the anterior border of the diagonal band of Broca (DBB). Multiple unit activity (MUA) recorded in the DM, basolateral-AMYG and m-SEPT showed a fluctuation with the estrous cycle in which the minimum level was observed on the day of proestrus and the maximum level was observed on the day of estrus. But MUA did not show a distinct fluctuation with the estrous cycle in the frontal lobe neocortex. A horizontal circular cut of the median region in the forebrain-limbic area including the m-SEPT and the anterior border of the DBB on the day of diestrus II induced vaginal cornification on the following day. Excision of the dorsal region of the anterior frontal lobe neocortex on the day of diestrus II increased the serum concentrations of luteinizing hormone (LH) in the afternoon of that day and induced vaginal cornification on the following day. Electrochemical stimulation (DC 120 microA, 30 sec) of the anterior frontal lobe neocortex just before the critical period of ovulation on the day of proestrus blocked the preovulatory surge of LH. Electrochemical stimulation of the anterior frontal lobe neocortex just after excision of the lateral amygdaloid nucleus (lateral-AMYG) including the basolateral-AMYG did not block the preovulatory surge of LH and ovulation. Electrochemical stimulation of the frontal neocortex after excision of the DM did not block the preovulatory LH surge. Excision of the m-SEPT showed a similar effect, but it had little effect on the blockade of the inhibition of LH secretion induced by electrochemical stimulation of the anterior frontal lobe neocortex. It became clear that the dorsal region of the anterior frontal lobe neocortex has an inhibitory function on the secretion of LH and ovulation through the nerve circuit including the DM, the basolateral-AMYG and the median region of the septal area. Then the anterior frontal lobe neocortex probably participates in the periodical rhythm of LH secretion with the estrous cycle.

Amygdala↗

PubMed2002

Automatic and controlled verbal-information processing in patients with frontal lobe lesions.

The selectivity of frontal lobe lesion effects in the domains of verbal-information processing has not been well established. The authors hypothesized that capacity-limited controlled processing would be more impaired than automatic processing in frontal lobe patients (FLPs). Fifteen FLPs were compared with 2 matched control groups: 14 posterior-lesion patients and 15 normal controls. Both behavioral and event-related brain potential (ERP) measures were collected. Results suggest that both automatic and controlled processing were affected by frontal lobe lesions. ERP results indicated that the main dificulty for the FLPs was in the perceptual stage of information processing. This rather unexpected result may be explained by a basic difficulty of FLPs in attending to a new stimulus in order to process it.

Adult↗

PubMed2006

Structured cueing on a semantic fluency task differentiates patients with temporal versus frontal lobe seizure onset.

Patients with frontal lobe dysfunction (e.g., Huntington's disease) reportedly benefit more from cueing on measures of semantic fluency than do patients with damage to temporal lobe structures (e.g., Alzheimer's disease). This differential benefit from cueing suggests that different neurocognitive functions are impaired in these two groups. Patients with frontal lobe dysfunction are presumed to have difficulty with the executive aspects of this generative fluency task, whereas patients with temporal lobe impairment are limited by deficits in semantic memory. We studied the performance of patients with complex partial seizures of frontal or temporal lobe onset, as determined by video/EEG monitoring, on standard and cued measures of semantic fluency administered in a counterbalanced sequence across groups. These groups did not differ significantly in terms of age, education, gender, age at seizure onset, total number of antiepileptic drugs, or IQ, and all patients subsequently underwent surgery for intractable epilepsy. Patients with frontal lobe dysfunction (FL group) performed significantly worse than patients with temporal lobe impairment (TL group) on the standard semantic fluency paradigm (TL group: M=18.4, SD=4.7; FL group: M=11.1, SD=5.3), t(27)=-3.75, P<0.001. Nevertheless, results of an ANCOVA demonstrated that the FL group showed significantly greater performance improvement than the TL group when provided with a cued semantic fluency format, even after controlling for baseline differences in ability on the standard semantic fluency task (TL group: M=0.45, SD=3.8; FL M=9.4, SD=5.1), F(1,29)=12.37, P=0.002. These findings support previous research suggesting that frontal and temporal structures contribute uniquely to semantic generative fluency and suggest that using a combination of standard and cued semantic fluency tasks may help confirm localization of seizure onset in partial epilepsy by localizing the associated cognitive dysfunction.

Adult↗

PubMed1990

Psychopathology of frontal lobe syndromes.

In this review, some basic aspects of frontal lobe functioning have been discussed and methods of testing for frontal lobe abnormalities outlined. It has been emphasized that the frontal lobes are affected in a number of diseases, which cover a broad spectrum of neuropsychiatric problems. Furthermore, it is suggested that the frontal lobes are involved in syndromes not traditionally thought to be related to frontal lobe dysfunction, for example, schizophrenia, and rarer presentations such as misidentification syndromes. Frontal lobe dysfunction often goes unrecognized, especially in patients who have normal neurologic testing and apparently intact IQ when routine methods of investigation are employed. Although marked disturbances of behavior following frontal lobe dysfunction have now been described for well over 120 years, these large areas of the human brain, and their links with some of the highest attributes of mankind, have been relatively neglected and are worthy of much further exploration by those interested in neuropsychiatric problems.

Brain Diseases↗

PubMed1976

Visual evoked responses and their dispersion pattern in frontal lobe tumours.

In patients with frontal lobe tumours the averaged visual evoked responses (AVER) and their dispersion pattern (DP) in visual areas were investigated before and at different periods after operation. Important changes in AVER (in amplitude and latency) were found in the patients with tumours on the midline or in one of the frontal lobes. The DP was abnormal in all the cases. There was no relation to visual acuity, tumour location and existance of intracranial hypertension. After operation, despite the clinical improvement, the alterations of AVERs or DPs were very marked and in some cases became even more important than before. The role of the frontal lobe in the organization of the responses to peripheral stimuli in the visual areas is discussed.

Adult↗

PubMed2005

Semantic priming in patients with right frontal lobe lesions.

Patients with unilateral, right frontal lobe damage (N=13) and matched controls (N=20) performed a task of lexical ambiguity resolution in order to explore the contribution of right frontal regions to lexical-semantic priming. Word triplets consisting of balanced homographs were presented to participants in four conditions: concordant, discordant, neutral, and unrelated. Controls demonstrated facilitation for concordant meanings of homographs, as evidenced by their faster reaction times in the concordant relative to the unrelated (baseline) condition, as well as a lack of facilitation for the discordant meaning relative to the neutral and concordant conditions. Results in patients with right frontal lobe damage differed depending on the site of the lesion. Patients with lesions restricted to the right medial frontal lobe only showed facilitation in the neutral condition, while those with lesions encroaching upon the right dorsolateral region demonstrated facilitation of both discordant and concordant meanings relative to the baseline condition. These results support a role for the right frontal lobe in semantic priming and suggest possible specialization within the right prefrontal cortex for the processing of lexical-semantic information.

Adult↗

PubMed2000

Disruption of attention to novel events after frontal lobe injury in humans.

OBJECTIVE: To investigate whether frontal lobe damage in humans disrupts the natural tendency to preferentially attend to novel visual events in the environment. METHODS: Nine patients with chronic infarctions in the dorsolateral prefrontal cortex (DLPFC) and 23 matched normal controls participated in a study in which subjects viewed repetitive background stimuli, infrequent target stimuli, and novel visual stimuli (for example, fragmented or "impossible" objects). Subjects controlled viewing duration by a button press that led to the onset of the next stimulus. They also responded to targets by pressing a foot pedal. The amount of time spent looking at the different kinds of stimuli, and the target detection accuracy and speed served as dependent variables. RESULTS: Overall, normal controls spent significantly more time than frontal lobe patients looking at novel stimuli. Analysis of responses across blocks showed that initially frontal lobe patients behaved like normal controls by directing more attention to novel than background stimuli. However, they quickly began to distribute their viewing time evenly between novel and background stimuli, a pattern that was strikingly different from normal controls. By contrast, there were no differences between frontal lobe patients and normal controls for viewing duration devoted to background and target stimuli, target detection accuracy, or reaction time to targets. Frontal lobe patients did not differ from normal controls in terms of age, education, estimated IQ, or mood, but were more apathetic as measured by self report and informants' judgments. Attenuated responses to novel stimuli significantly correlated with degree of apathy. CONCLUSIONS: This study demonstrates that DLPFC injury selectively impairs the natural tendency to seek stimulation from novel and unusual stimuli. These data provide the first quantitative behavioural demonstration that the human frontal lobes play a critical part in directing and sustaining attention to novel events. The impairment of novelty seeking behaviour may contribute to the characteristic apathy found in patients with frontal lobe injury.

Aged↗

PubMed1991

Positron emission tomography studies of frontal lobe function: relevance to psychiatric disease.

The frontal lobes in man include about one-third of the total cortical area of the cerebrum, a considerably greater proportion than in other primates. It is likely that the frontal lobes subserve the most complex of cognitive functions including will and consciousness. During the performance of willed actions (spontaneous selection of actions without help from external cues) an increase of activity can be observed in dorsolateral prefrontal cortex. Critically, there is no increased activity in this location when the same actions are performed routinely. Such observations, which systematically use positron emission tomography (PET) in conjunction with specific cognitive activations, should make it possible (a) to specify more precisely the cognitive components comprising 'frontal' attributes such as willed behaviour and planning, (b) to relate these components to particular frontal lobe areas, and (c) to show how these frontal lobe areas interact with other parts of the brain. Psychotic patients typically show abnormalities of willed behaviour (e.g. poverty of speech and action) and consciousness (e.g. hallucinations, delusions of control). PET studies of frontal lobe function in patients with these signs and symptoms should not only provide information about the pathophysiology of these disorders, but also increase our knowledge of the brain systems underlying the most complex human faculties.

Attention↗

PubMed2006

Surgical treatment of drug-resistant nocturnal frontal lobe epilepsy.

Of the cases with nocturnal frontal lobe epilepsy (NFLE) approximately 30% are refractory to antiepileptic medication, with several patients suffering from the effects of both ongoing seizures and disrupted sleep. From a consecutive series of 522 patients operated on for drug-resistant focal epilepsy, 21 cases (4%), whose frontal lobe seizures occurred almost exclusively (>90%) during sleep, were selected. All patients underwent a comprehensive pre-surgical evaluation, which included history, interictal EEG, scalp video-EEG monitoring, high-resolution MRI and, when indicated, invasive recording by stereo-EEG (SEEG). There were 11 males and 10 females, whose mean age at seizure onset was 6.2 years, mean age at surgery was 24.7 years and seizure frequency ranged from <20/month to >300/month. Nine patients reported excessive daytime sleepiness (EDS). Prevalent ictal clinical signs were represented by asymmetric posturing (6 cases), hyperkinetic automatisms (10 cases), combined tonic posturing and hyperkinetic automatisms (4 cases) and mimetic automatisms (1 case). All patients reported some kind of subjective manifestations. Interictal and ictal EEG provided lateralizing or localizing information in most patients. MRI was unrevealing in 10 cases and it showed a focal anatomical abnormality in one frontal lobe in 11 cases. Eighteen patients underwent a SEEG evaluation to better define the epileptogenic zone (EZ). All patients received a microsurgical resection in one frontal lobe, tailored according to pre-surgical evaluations. Two patients were operated on twice owing to poor results after the first resection. Histology demonstrated a Taylor-type focal cortical dysplasia (FCD) in 16 patients and an architectural FCD in 4. In one case no histological change was found. After a post-operative follow-up of at least 12 months (mean 42.5 months) all the 16 patients with a Taylor's FCD were in Engel's Class Ia and the other 5 patients were in Engel's Classes II or III. After 6 months post-surgery EDS had disappeared in the 9 patients who presented this complaint pre-operatively. It is concluded that patients with drug-resistant, disabling sleep-related seizures of frontal lobe origin should be considered for resective surgery, which may provide excellent results both on seizures and on epilepsy-related sleep disturbances. An accurate pre-surgical evaluation, which often requires invasive EEG recording, is mandatory to define the EZ. Further investigation is needed to explain the possible causal relationships between FCD, particularly Taylor-type, and sleep-related seizures, as observed in this cohort of NFLE patients.

Adolescent↗

PubMed2003

Inhibitory attentional control in patients with frontal lobe damage.

The performance of a group of frontal lobe lesion and a group of frontal lobe dementia patients was compared with the performance of their respective matched normal control groups on two tests of inhibitory attentional control-the stop-signal reaction time task and a negative priming task. Both patient groups responded significantly slower than their respective normal control groups, but they showed only marginally significant selective impairments on the measures of inhibition. The data suggest that the specific inhibitory processes evaluated by these two tests are, in general, spared in patients with focal frontal lobe lesions or frontal lobe degeneration.

Adult↗