Visual and quantitative ictal EEG predictors of outcome after temporal lobectomy

PURPOSE: We investigated whether visual and quantitative ictal EEG analysis could predict surgical outcome after anteromesial temporal lobectomy (AMTL) in which mesial structures, basal, and temporal tip cortex were resected. METHODS: We retrospectively reviewed 282 presurgical scalp-recorded ictal EEGs (21- to 27-channel) from 75 patients who underwent AMTL. We examined the pattern of seizure onset (frequency, distribution, and evolution) and estimated the principal underlying cerebral generators by using a multiple fixed dipole model that decomposes temporal lobe activity into four sublobar sources (Focus 1.1). We correlated findings with a 2-year postoperative outcome. RESULTS: Sixteen patients had seizures with a well-lateralized, regular 5 to 9-Hz rhythm at onset, that most often had a temporal or subtemporal distribution. All patients became seizure free after surgery. In 51 patients, seizure onset was remarkable for lateralized slow rhythms (<5 Hz), which sometimes appeared as periodic discharges, were often irregular and stable only for short periods (<5 s), and had a widespread lateral temporal distribution. Among these a favorable surgical outcome was encountered in patients with seizures having prominent anterior-tip sources ( 16 of 17 seizure free), whereas those with dominant lateral or oblique sources had a less favorable outcome (three of 14 and 13 of 18, respectively). Irregular, nonlateralized slowing characterized seizure onsets in eight patients. Three patients became seizure free after surgery. CONCLUSIONS: Both visual and quantitative sublobar source analysis of scalp ictal EEG can predict surgical outcome in most cases after AMTL and complement non-invasive presurgical evaluation.     

Factors associated with work outcome after anterior temporal lobectomy for intractable epilepsy

PURPOSE: Whereas the effect of anterior temporal lobectomy on seizure frequency is well recognized, less is known about its impact on work status. METHODS: One hundred thirty-four of 190 consecutive patients with temporal lobectomy participated in this study. Eligibility criteria were developed to ensure that only patients with the potential of achieving specific outcomes were included in the corresponding analyses. RESULTS: After surgery, significantly more patients were independent in activities of daily living (p < 0.001) or able to drive (p < 0.001). Income from work also increased (p < 0.01). Nearly one fifth of the patients who were eligible for analysis had either a gain (8%) or a loss (11%) of full- or of part-time work. Univariate analyses revealed the following factors to be associated with full-time work after surgery: student or full-time work within a year before surgery, full-time work experience before surgery, full- or part-time employment experience before surgery, no disability benefits before surgery, low postsurgical seizure frequency, improved postsurgical seizure control, excellent postsurgical seizure control, driving after surgery, and further education after surgery (p < 0.05). Significant factors on multivariate analysis were being a student or having full-time work within a year before surgery [odds ratio, 16.2 (95% CI, 4.3-60.5)], driving after surgery [15.2 (3.2-72.0)], and obtaining further education after surgery [9.2 (2.2-53.0)]. CONCLUSIONS: Anterior temporal lobectomy for intractable epilepsy improves activities of daily living and the ability to drive. Work outcome of this surgery is influenced by presurgical work experience, successful postsurgical seizure control especially to allow driving, and obtaining further education after surgery.     

Single photon emission tomography in temporal epilepsy: interictal and ictal studies with visual and semi quantitative analysis

Single photon emission tomography (SPECT) was performed in 27 patients with refractory complex partial seizures from the temporal lobes due to mesial temporal sclerosis. Independent blinded observers assessed the 28 interictal studies and 9 ictal/postictal studies. Visual analysis of interictal studies detected hypoperfusion in 22, ipsilateral to the epileptogenic zone in 19 (67%) and contralateral in 3 (10.7%). Quantified temporal lobe asymmetry, greater than a previously derived normal range, correctly identified the epileptogenic zone in 16 (61.5%) with false lateralization in 4 (15.3%). In all 9 cases in which they were performed, ictal/postictal studies showed hyperperfusion at the region of epileptic focus. In 3 patients with complex partial seizures followed by symmetric generalized tonic-clonic seizures, hyperperfusion restricted to the temporal lobe was demonstrated. In 5 of these patients the interical studies were unable to demonstrate localized changes. There were no significant correlations between SPECT findings and clinical parameters or EEG slowing in the temporal lobes.     

Influence of head trauma on outcome following anterior temporal lobectomy

BACKGROUND: There is controversy in the literature regarding the importance of risk factors in developing epilepsy and seizure outcome following anterior temporal lobectomy. Some of the existing studies may be biased because of patient selection and limitations in determining predisposition. OBJECTIVE: To investigate the role of risk factors for epilepsy in determining outcome following anterior temporal lobectomy. PATIENTS AND METHODS: We identified 102 patients in a consecutive surgery series for epilepsy from a tertiary center with a minimum of 1-year postoperative follow-up. Risk factors for epilepsy were determined prospectively on at least 3 occasions before anterior temporal lobectomy. Risk factors investigated were a history of febrile convulsions, family history of epilepsy, significant head trauma, history of meningitis, history of encephalitis, or significant perinatal insult. Foreign tissue lesions on magnetic resonance imaging was also included if an anterior temporal lobectomy was performed for presumed dual pathologic findings (hippocampus and lesion). Outcome was determined using Engel's classification. For statistical analysis we used successive logistic regression analysis, chi(2) test, Fisher exact test, and t test. RESULTS: Of the 102 patients, 13 had no identified risk factor for epilepsy, 49 had 1 identified risk factor, and 40 had more than 1. Frequencies were 39 febrile convulsions (15 complex febrile convulsions), 29 head trauma, 22 with lesions seen on magnetic resonance imaging, 12 history of meningitis, 2 history of encephalitis, 19 family history of epilepsy, and 4 perinatal insult. Seventy-one (70%) were classified as Engel's class I, with 56 patients continuously free of seizures at follow-up. Those without risk factor were as likely to be rendered free of seizures following anterior temporal lobectomy as those with a risk factor (P = .27). No risk factor alone or in combination was correlated with complete freedom from seizures following anterior temporal lobectomy, but the presence of head trauma, alone or in combination, was correlated with continued seizures following anterior temporal lobectomy (P = .03; odds ratio, 2.6). Better outcomes were not seen in those with head trauma before the age of 5 years (P = .57). These findings did not change if all those with lesions on magnetic resonance imaging were excluded in the analysis. Those with a history of head trauma were as likely to have pathologic evidence of mesial temporal sclerosis as others (P = .82). CONCLUSIONS: Patients with a history of significant head trauma are less likely to become free of seizures following anterior temporal lobectomy. No other risk factor correlated with a statistically significant greater or lesser chance of freedom from seizures. This information may be used in preoperative counseling of patients.     

Neuropsychological outcome following anterior temporal lobectomy in patients with and without the syndrome of mesial temporal lobe epilepsy.

The nature, pattern, and degree of neuropsychological change following anterior temporal lobectomy (ATL) were examined as a function of the presence or absence of the syndrome of mesial temporal lobe epilepsy (MTLE). Fifty-four patients exhibited the syndrome of MTLE, while 34 patients were without the syndrome (non-MTLE). The test-retest performance of a group of 40 epilepsy patients who did not undergo surgery was used to derive regression based estimates of test-retest change. Overall, the MTLE group did not show significant cognitive decline following ATL. In contrast, the left non-MTLE group showed significant declines on verbal memory, confrontation naming, and verbal conceptual ability. Further, verbal memory was the most substantial area of decline, and was independent of seizure outcome. Clinical and theoretical implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual memory change after anterior temporal lobectomy: a base rate analysis using regression-based outcome methodology

PURPOSE: To characterize patterns of base rate change on measures of verbal and visual memory after anterior temporal lobectomy (ATL) using a newly developed regression-based outcome methodology that accounts for effects of practice and regression towards the mean, and to comment on the predictive utility of baseline memory measures on postoperative memory outcome. METHODS: Memory change was operationalized using regression-based change norms in a group of left (n = 53) and right (n = 48) ATL patients. All patients were administered tests of episodic verbal (prose recall, list learning) and visual (figure reproduction) memory, and semantic memory before and after ATL. RESULTS: ATL patients displayed a wide range of memory outcome across verbal and visual memory domains. Significant performance declines were noted for 25-50% of left ATL patients on verbal semantic and episodic memory tasks, while one-third of right ATL patients displayed significant declines in immediate and delayed episodic prose recall. Significant performance improvement was noted in an additional one-third of right ATL patients on delayed prose recall. Base rate change was similar between the two ATL groups across immediate and delayed visual memory. Approximately one-fourth of all patients displayed clinically meaningful losses on the visual memory task following surgery. Robust relationships between preoperative memory measures and nonstandardized change scores were attenuated or reversed using standardized memory outcome techniques. CONCLUSIONS: Our results demonstrated substantial group variability in memory outcome for ATL patients. These results extend previous research by incorporating known effects of practice and regression to the mean when addressing meaningful neuropsychological change following epilepsy surgery. Our findings also suggest that future neuropsychological outcome studies should take steps towards controlling for regression-to-the-mean before drawing predictive conclusions.     

Single photon emission computed tomography (SPECT) in a patient with bilateral temporal seizures: correlation between ictal EEG and postictal/ictal SPECT

We report a patient with bilateral independent temporal lobe seizures in whom two [99mTc]HMPAO single photon emission computed tomograph (SPECT) scans were performed during two different seizures. In the first periictal SPECT, [99mTc]HMPAO was injected in the interval between two closely spaced seizures (one localized in the left temporal lobe and the other in the right temporal lobe). SPECT images showed hypoperfusion in the left lateral temporal lobe, hyperperfusion of the left mesial temporal region, and pronounced hyperperfusion in the right anterior temporal lobe. These results suggest both a postictal left temporal SPECT pattern and an ictal right temporal pattern. In the second periictal SPECT, [99mTc]HMPAO was injected immediately after a right temporal lobe seizure and showed right lateral temporal lobe hypoperfusion and right mesial hyperperfusion, suggesting a postictal right temporal SPECT pattern. Interpretation of the periictal SPECT should take into account EEG changes at the time or in the minutes immediately after injection of [99mTc]HMPAO.     

Differences between nouns and verbs after anterior temporal lobectomy.

To test the claim that lesions of left anterior and middle temporal cortical structures specifically impair processing of nouns but not verbs, 56 left-hemisphere-language-dominant patients who had undergone anterior temporal lobectomy (ATL) completed tasks assessing confrontation naming of pictured objects and actions, generation of synonyms for nouns and verbs, and semantic lexical judgments about nouns and verbs. Compared with right ATL patients left ATL patients were impaired across different tasks that assessed naming and comprehension of high-imageability as well as low-imageability nouns. These groups did not differ, however, in verb naming or comprehension on most tasks. Results are consistent with the hypothesized specialization of left temporal lobe structures for processing nouns and suggest that naming problems commonly seen after left ATL extend beyond difficulties with retrieving object names and may be related to subtle disturbances in comprehension of the meanings underlying nominal word forms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychiatric outcome of temporal lobectomy for epilepsy: incidence and treatment of psychiatric complications

PURPOSE: To determine the incidence of psychiatric disorders before and after surgical treatment for partial epilepsy and to document the effectiveness of their treatment. METHODS: Fifty consecutive patients treated surgically for focal epilepsy (44 temporal and six frontal) were evaluated by established neuropsychiatric methods before surgery and over a mean period of 2 years after surgery. The patients with interictal dysphoric disorders, with or without psychotic episodes, were treated with tricyclic antidepressant medication alone or combined with serotonin selective reuptake inhibitors and, if necessary, with the addition of risperidone. RESULTS: Before surgery, 25 (57%) of the 44 patients with temporal lobe epilepsy had dysphoric disorders. After surgery, 17 (39%) of the 44 patients experienced either de novo psychiatric complications (six psychotic episodes, six dysphoric disorders, and two depressive episodes) or exacerbation of preoperative dysphoric disorder (three patients). Eight previously intact patients of the 19 (42%) developed dysphoric disorders after surgery that were significantly related to recurrence of seizures. All psychiatric complications occurred in the first 2 months after surgery, except for the six patients intact before surgery, who had a recurrence of seizures. A significant predictor of ultimate excellent psychiatric outcome was complete absence of seizures after surgery. All postoperative psychiatric complications remitted on treatment with psychotropic medication in the compliant patients. CONCLUSIONS: An exceptional psychiatric morbidity is associated with the months after temporal lobectomy. Possible pathogenetic mechanisms are discussed. Antidepressant drugs are very effective in treating the psychiatric disorders of chronic epilepsy; their use in conjunction with the surgical treatment of epilepsy appears to be crucial for the overall positive outcome of a significant number of patients.     

Naming decline after left anterior temporal lobectomy correlates with pathological status of resected hippocampus

PURPOSE: To evaluate the determinants of postoperative change in visual confrontation naming ability and the differential sensitivity of two common tests of confrontation naming. METHODS: In a group of 99 patients undergoing lobectomy of the left, language-dominant anterior temporal lobe, we examined naming ability using two measures: the 60 item Boston Naming Test (BNT), and the Visual Naming (VN) subtest of the Multilingual Aphasia Examination (MAE). ATL entailed resection of lateral temporal lobe followed by microsurgical complete removal of hippocampus. Language mapping was not performed. The status of the resected hippocampus was graded on a scale 0-4 of hippocampal sclerosis (HS). A dichotomous grouping HS- (grades 0 and 1, n = 34) and HS+ (grades 3 and 4, n = 61) was effected. Age at surgery, age of epilepsy onset, sex, extent of lateral temporal resection, Full-Scale IQ (FSIQ), and preoperative naming scores were also examined as potential predictors of pre- versus postoperative naming change. RESULTS: Preoperative BNT and VN scores were significantly worse for HS+ than for HS- (BNT, p < 0.05; VN, p = 0.001). Postoperatively, BNT and VN scores significantly declined for HS- as compared with HS+ patients (p < 0.001). For individual risk, the 90th centile of reliable change index (RCI) was used. By this criterion, of the total sample, 39% evidenced decline on the BNT and 17% evidenced decline on the VN. Logistic regression analysis with backward elimination showed HS to be the only predictor of decline in BNT and HS and sex to be the only predictors of VN decline. Males were more at risk than females. Age, age at onset, extent of lateral resection, preoperative scores, and FSIQ were not predictors. Using age at onset as a proxy for HS+/HS- we calculated probabilities for naming decline for given onset age. CONCLUSIONS: Both preoperative and postoperative change in naming ability are associated with the pathological status of the hippocampus. The potential interpretations and implications of these findings are discussed.     

Doors and People: Visual and verbal memory after unilateral temporal lobectomy.

The study investigated the ability of the A. D. Baddeley et al (1994) Doors and People Memory Battery to discriminate between patients with left and right unilateral temporal lobectomy (TL). Patients, 47 of whom had undergone en bloc resection (23 left TL and 24 right TL), were tested on the memory battery. The results showed that verbal memory functioning was significantly more impaired in the left TL group, whereas visual memory was more impaired in the right TL group. Recall memory was slightly more impaired than recognition memory overall in the 2 patient groups. It is concluded that the test provides a neuropsychologically valid and sensitive measure of visual and verbal memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amygdala atrophy and seizure outcome after temporal lobe epilepsy surgery

Surgical outcome in hippocampal atrophy (n = 44) and amygdalohippocampal atrophy (n = 14) were compared. Hippocampal atrophy had better seizure-free outcome than amygdalohippocampal atrophy (80% versus 50%, p = 0.043). Severity of hippocampal atrophy correlated with duration of epilepsy in patients with hippocampal atrophy (r = 0.4, p = 0.007), but not in those with amygdalohippocampal atrophy, suggesting that these two groups may have a different pathogenesis.     

Usefulness of ictal and interictal 99mTc ethyl cysteinate dimer single photon emission computed tomography in patients with refractory partial epilepsy

OBJECTIVE: The aim was to investigate the feasibility of recording the electrical auditory brain stem response (EABR) evoked by electrical stimulation at the promontory (Prom-EABR) as a tool to assist selection of the ear for cochlear implantation in young children. STUDY DESIGN: The study group consisted of young children for whom the decision to proceed with implantation with the Nucleus mini 22-channel cochlear implant (Cochlear (UK) Ltd., London, UK) had already been made. SETTING: The Prom-EABR was recorded after the children had been anesthetised, but before the start of surgery. PATIENTS: A group of 25 children (11 boys and 14 girls), whose age at implantation ranged from 2 years 11 months to 6 years 8 months (mean age, 4 years 5 months), were investigated. INTERVENTION: Recordings of the Prom-EABR were used to determine which ear would receive the cochlear implant, providing there were no preexisting contraindications regarding selection of the ear. MAIN OUTCOME MEASURE: It has been suggested from earlier studies that the characteristics of the amplitude input/output (I/O) function of the EABR are related to neuronal survival. If the ear with the "better" I/O function is chosen for implantation, it might be expected that these children will perform better on average than those in whom the ear has been selected at random. RESULTS: Reliable recordings of the Prom-EABR were achieved in 40 ears (80%) of the 50 ears in the study. In 20 of the 25 children the technique was actively employed for selection of the ear for implantation. CONCLUSIONS: Recording of the Prom-EABR in the operating theater is a viable technique. Future analysis of long-term outcome measures of performance with the implant will confirm or dispute the benefit of ear selection using the Prom-EABR.     

Conditioning of ictal and interictal behaviors in rats by amygdala kindling: Context as the conditional stimulus.

The authors showed that conditional effects of the stimulation environment modulate both the ictal and interictal behaviors of rats subjected to amygdala kindling. Rats received 53 stimulations to the left basolateral amygdala in 1 conditional stimulus (CS) context (CS+) and 53 sham stimulations (the stimulation lead was attached but no current was delivered) in another context (CS-), quasirandomly over 54 days. Three kinds of conditional effects were observed, First, after several stimulations, less ambulatory activity, more freezing, and less rearing reliably occurred in the CS + context than in the CS context. Second, after 45 stimulations, all of the rats chose the CS - context over the CS + context in a conditioned place preference test. Third, when the rats were finally stimulated in the CS- context, their motor seizures were less severe: Latencies were longer, motor seizures were shorter, convulsive patterns were of a lower class, and there were fewer falls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Periventricular nodular heterotopia and intractable temporal lobe epilepsy: poor outcome after temporal lobe resection

We describe 5 women and 5 men with periventricular nodular heterotopia and electroclinical features suggestive of temporal lobe epilepsy, who were surgically treated for control of medically refractory seizures. Magnetic resonance imaging revealed bilateral periventricular nodular heterotopia in 7 of the 10 patients. Because of the lack of clear localization, 6 patients were studied with intracranial depth electrode recordings. Seizures were of hippocampal onset (3 patients), regional temporal lobe onset (2 patients), or occipital-temporal onset (1 patient). Anterior temporal lobectomy was performed in 6 patients; selective amygdalohippocampectomy, in 1; and anterior temporal lobectomy plus resection of the heterotopic tissue, in 3. None of the 9 patients followed for more than 12 months postoperatively were seizure free. Two patients were initially seizure free for approximately 18 months, but then seizures recurred. One patient had a major reduction in seizure frequency at a 39-month follow-up after most of the unilateral heterotopic tissue was included in the temporal resection. Temporal resection did not lead to a long-term favorable outcome in this group of patients with periventricular nodular heterotopia and epileptogenic discharges involving the temporal lobe. This suggests a more widespread disorder with epileptogenic activity possibly originating in or near the heterotopic tissue. The clinical and electrographic features of periventricular nodular heterotopia pointing to temporal lobe origin are misleading and temporal resection does not result in long-term cessation of seizures.     

Role of the hippocampus in sex differences in verbal memory: Memory outcome following left anterior temporal lobectomy.

The authors examined the neural and cognitive bases for sex differences in verbal memory in 57 patients who underwent left anterior temporal lobectomy (ATL) for the treatment of intractable seizures. On the California Verbal Learning Test (D. C. Delis, J. H. Kramer, E. Kaplan, & B. A. Ober, 1987), women recalled more words than men both before and after surgery, regardless of the extent of hippocampal damage. Extent of hippocampal sclerosis was related to memory loss in both men and women. Women's superiority in verbal memory appears to result in part from their use of an efficient encoding strategy. Women were more likely than men to use semantic clustering both before and after ATL, and sex differences in word recall were attenuated after scores were adjusted for semantic clustering. There was no effect of ATL on semantic clustering. Taken together, these results suggest that sex differences in verbal memory are not due to differences in the integrity of the left hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Non-hereditary +hyperekplexia. Study of a patient with unusual ictal EEG features and review of the literature

INTRODUCTION AND CLINICAL CASE: We present a male patient which presented distal muscular stiffness, from the first hours of the life. At this time, he also presented episodes of generalized muscular hypertonia with cyanosis and apnoea, started by somato-sensorial stimuli. Those episodes were terminated by passive flexion of the extremities and the head. Later, dream myoclonic jolts appeared. EEG tracings during hypertonic episodes showed an initial artefact potential followed by bursts of rhythmic and repetitive acute potentials in the bilateral fronto-central regions, at a 20-22 Hz frequency, similar to an epileptiform spike-wave burst. The EMG showed a continuous muscular activity, suppressed by rest and the administration of diazepam. Treatment with oral diazepam has been very effective. Now, the patient is four years old, is asymptomatic and continues treatment with oral diazepam. If the dose is decreased, the child starts unstable march, startle response on somatosensory stimuli with falls, and above all nocturnal myoclonia. The patient does not have familiar antecedents of hyperekplexia, even in its minor form. CONCLUSION: Clinical picture suggests us a not familiar form of hyperekplexia.     

Operative strategy in patients with MRI-identified dual pathology and temporal lobe epilepsy

The liver is the most common site of hematogenous metastases from colorectal carcinoma. Kupffer cells (KC), which line the hepatic sinusoids, may form the first line of defense against circulating tumor cells. The purpose of this study was to determine the effect of hepatic metastases and intra-abdominal tumor growth on KC binding of human colorectal carcinoma (HCRC) cells. MIP-101, a poorly metastatic cell line, and CX-1, a highly metastatic cell line, were injected intrasplenically into nude mice and KC were isolated by collagenase perfusion at varying intervals after injection. Conditioned media were collected from MIP-101, CCL 188 and CX-1 to determine their in vitro effect on KC function. KC from MIP-101 injected mice (14% liver metastases, 100% splenic tumors) bound a significantly greater number of MIP-101 and clone A cells than CX-1 cells in vitro. KC isolated from mice 5 weeks after CX-1 injection (100% liver metastases) also showed increased binding of MIP-101 and clone A cells compared to CX-1 cells. Similar results were obtained when tumor cell binding to normal human liver KC was compared to binding to KC from human livers from patients with hepatic metastasis from colorectal cancer. In contrast KC obtained from mice 3 weeks after CX-1 injection (44% liver metastases) showed significantly decreased binding of MIP-101 and clone A cells. The conditioned medium from CX-1 cells significantly decreased the in vitro binding of both MIP-101 and CX-1 by KC. These results indicate that the ability of KC to bind HCRC cells (which precedes phagocytosis and tumor cell killing) is a dynamic function and affected by concomitant tumor growth. HCRC cells may alter KC function via the production of specific tumor-derived soluble factors. In order to devise new and more effective therapeutic options in the treatment of liver metastases the nature of this tumor cell-KC interaction must be better understood.     

Functional results and long-term outcome after bilateral lung transplantation for pulmonary hypertension

With the growing popularity of soccer both in the United States and worldwide, reports of adverse effects of 'heading' on brain function are a source of concern. This article reviews the related research literature on neurologic and neuropsychological findings. Neurologic and neuropsychological abnormalities have been reported in a significant minority of older former professional players in Norway. Purportedly unrelated to age, the most prominent findings were cerebral atrophy and impairment on intelligence test abilities that are particularly vulnerable to brain damage. Also noteworthy in these retired players were persistent physical, cognitive, and emotional complaints consistent with a postconcussive syndrome. Younger amateur players appear to be free of major abnormalities, although some report persistent difficulties with memory and concentration. The severity of these complaints may be related to a history of soccer-related head injuries and not necessarily specific to heading. Research findings specific to heading are not more than suggestive at best, and clarification of the risks of heading a soccer ball awaits more definitive studies.     

Learning in monkeys after combined lesions in frontal and anterior temporal lobes.

Assigned 19 rhesus monkeys to 2 unoperated control groups, a group sustaining prefrontal lobectomy, and a group with prefrontal lobectomy plus removal of the anterior temporal neocortex. Ss were compared on delayed response ability, as well as on the ability to make object discriminations and to form learning sets. The combined frontal-temporal lesion did not increase the delayed response deficit produced by frontal damage alone, but it significantly increased difficulty in making 2-object discriminations and apparently also depressed oddity discrimination performance. Ability to form learning sets was not impaired in either lesioned group. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)