Targeted sonodynamic destruction of glioblastoma cells using antibody-titanium dioxide nanoparticle conjugates

Aim: We present data on sonodynamic therapy (SDT) against glioblastoma cells utilizing titanium dioxide (TiO₂) nanoparticles conjugated to anti-EGFR antibody. Materials & methods: TiO₂ nanoparticles were bound to anti-EGFR antibody to form antibody-nanoparticle conjugates (ANCs), then characterized by x-ray photoelectron spectroscopy and transmission electron microscopy. Cells underwent ultrasound and assessment on viability, reactive oxygen species and apoptosis were performed. Results: X-ray photoelectron spectroscopy analysis revealed the formation of an ANC. Transmission electron microscopy showed internalization of the ANCs by glioblastoma cells. With SDT, cell viabilities were reduced in the presence of ANCs, reactive oxygen species production was formed, but minimal effect on apoptosis was seen. Conclusion: For the first time, an ANC can be used with SDT to kill glioblastoma cells.

Light-driven transformation processes of anisotropic silver nanoparticles

The photoinduced formation of silver nanoprisms from smaller silver seed particles in the presence of citrate anions is a classic example of a photomorphic reaction. In this case, light is used as a convenient tool to dynamically manipulate the shape of metal nanoparticles. To date, very little is known about the prevailing reaction mechanism of this type of photoreaction. Here we provide a detailed study of the shape transformation dynamics as a function of a range of different process parameters, such as photon energy and photon flux. For the first time, we provide direct evidence that the photochemical synthesis of silver nanoprisms from spherical seed nanoparticles proceeds via a light-activated two-dimensional coalescence mechanism. On the other hand, we could show that Ostwald ripening becomes the dominant reaction mechanism when larger silver nanoprisms are grown from photochemically synthesized smaller nanoprisms. This two-step reaction proceeds significantly faster and yields more uniform, sharper nanoprisms than the classical one-step photodevelopment process from seeds. The ability to dynamically control nanoparticle shapes and properties with light opens up novel synthesis avenues but also, more importantly, allows one to conceive new applications that exploit the nonstatic character of these nanoparticles and the ability to control and adjust their properties at will in a highly dynamic fashion.

Measurements of adult lingual tonsil tissue in health and disease

Objectives: To report computed tomography (CT) measurements of lingual tonsil tissue (LTT) in patients with laryngopharyngeal reflux (LPR), obstructive sleep apnea-hypopnea syndrome (OSAHS), both LPR and OSAHS, or neither disease.

Study Design: Retrospective chart review.

Setting: Tertiary care center.

Subjects and Methods: Ninety-eight patients with CT scans including the tongue base and complete historical data regarding the presence or absence of symptoms, signs, and laboratory confirmation of LPR and/or OSAHS were included. LTT was measured on CT. Charts of patients meeting inclusion criteria were subsequently reviewed and patients were divided into four groups: 1) those without LPR or OSAHS, 2) those with LPR only, 3) those with OSAHS only, and 4) those with both LPR and OSAHS. Statistical analysis focused on correlating LTT thickness with the presence or absence of LPR and/or OSAHS.

Results: The mean LTT thickness for group 1 (21 patients without reflux or OSAHS) was 0.937 mm (range 0-2.67 mm). The mean for group 2 (29 patients with LPR only) was 3.35 mm (range 0-7.4 mm). The mean for group 3 (16 patients with OSAHS only) was 4.29 mm (range 0-9 mm). The mean for group 4 (32 patients with LPR and OSAHS) was 4.00 mm (range 0-19.2 mm). The mean for group 1 was lower than the other 3 groups ( P < 0.001).

Conclusion: CT images including the tongue base allow precise measurement of LTT thickness. LTT > 2.7 mm was not identified in patients without OSAHS or LPR. The mean LTT for patients with LPR and/or OSAHS was significantly greater than for patients without either disease.

The role of intraoperative micro-Doppler ultrasound in verifying proper clip placement in intracranial aneurysm surgery

We present the results of a retrospective study employing intraoperative micro-Doppler ultrasonography (MDU) in verifying proper clip placement during cerebral aneurysmal surgery. One hundred and thirty-four patients surgically treated for 147 intracranial aneurysms were studied. Thirteen patients harboring 17 aneurysms were surgically treated on an elective basis, while 121 patients with 130 aneurysms, presented with subarachnoid hemorrhage (SAH). Blood flow velocities of the parent and adjacent vessels as well as the aneurysmal sac were measured using a Conforma Micro-Doppler (Cook Vascular Inc., Leechburg, PA, USA). Pre- and post-operative cerebral angiography was obtained in all our patients. In 23 aneurysms (15.6%) there was decreased or absent flow in the parent vessel or in one of the adjacent vessels after clipping. In another 19 aneurysms (12.9%), MDU demonstrated flow through the aneurysmal dome even though the aneurysmal neck appeared to be totally obliterated. Presence of SAH, anatomic location and size of the aneurysm were associated with improper clip placement in a statistically significant fashion. The false positive rate for MDU was 2% while there were no false negative findings in our study. MDU appears to be a non-invasive, reliable alternative methodology to intra-operative angiography. This inexpensive method may lend itself to routine usage in aneurysm surgery.

The Role of the Cannabinoid CB2 Receptor in Pain Transmission and Therapeutic Potential of Small Molecule CB2 Receptor Agonists

This review gives a brief overview of the expression patterns, molecular pharmacology and physiological role of the cannabinoid 2 receptor (CB2) in pain. Particular emphasis is given to the therapeutic utility of CB2 receptor agonists. Through studies utilizing selective CB2 receptor agonists, non-selective cannabinoid agonists in conjunction with selective CB1 and CB2 receptor antagonists, or CB2 receptor knockout mice, it is now clear that this receptor plays a critical role in nociception. To this end, CB2 receptors have been shown to modulate acute pain, chronic inflammatory pain, post-surgical pain, cancer pain and pain associated with nerve injury. Here we review these studies and the compounds that were utilized. We hypothesize the mechanism of action by which the CB2 receptor could be involved in these processes. Finally we summarize the most recent novel chemical scaffolds that are being investigated towards advancing selective CB2 receptor agonists into the clinic. Many new pharmacological agents have been identified by high throughput screening and small molecule lead discovery and optimization in the past 10 years. It is anticipated that at least some of these agents may ultimately constitute effective new pain therapeutics that lack the side effects associated with traditional cannabinoid ligands.

Extraradicular diffusion of hydrogen peroxide and pH changes associated with intracoronal bleaching of discoloured teeth using different bleaching agents

AIM

To evaluate the extraradicular pH and hydrogen peroxide (HP) diffusion when either 35% carbamide peroxide (CP), 35% HP or sodium perborate (SP) is used for intracoronal bleaching of artificially discoloured teeth.

METHODOLOGY

Single rooted extracted human premolars were stained with whole blood cells. After shaping and cleaning, they were root filled and a base cement placed 1 mm below the buccal cementoenamel junction (CEJ). Four cemental defects were prepared just below the CEJ on each root surface. The teeth were randomly divided into four groups of 11 specimens, and intracoronally bleached using CP, HP, SP or distilled water (CL). Each tooth was suspended in a vial of distilled water and bleached for 7 days. The pH of the extraradicular distilled water was tested at 0, 1, 2 and 7 days and the HP that diffused through the root quantified using the Ferrous Oxidation-Xylenol Orange 2 Assay. The results were analysed using the one-way anova and Scheffe tests.

RESULTS

Carbamide peroxide produced the greatest increase and HP the least pH change (P < 0.05 except day 1), SP was intermediate. From day 1 onwards, radicular diffusion of HP was greatest with HP and least with CP (P < 0.01), again SP was intermediate. There was no significant difference between CP and SP.

CONCLUSIONS

Carbamide peroxide had very low levels of extraradicular diffusion of HP, in the presence of cemental defects. It could be an alternative to the other intracoronal bleaching agents.

An in vitro comparison of the bleaching efficacy of 35% carbamide peroxide with established intracoronal bleaching agents

AIM

To evaluate the bleaching efficacy of 35% carbamide peroxide, 35% hydrogen peroxide and sodium perborate for intracoronal bleaching of root filled discoloured teeth.

METHODOLOGY

Extracted premolars were artificially stained using whole blood then root canal treatment was performed. After obturation, a 2 mm intermediate base was placed 1 mm below the buccal amelo-cemental junction. Intracoronal bleaching was performed in 11 teeth per group, using either 35% carbamide peroxide gel (group CP), 35% hydrogen peroxide gel (group HP) or sodium perborate mixed with distilled water (group SP). The bleaching agents were replaced after 7 days. The shade of the teeth was evaluated at day 0, 7 and 14. The results were analysed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U-test.

RESULTS

At the end of 7 days, both groups CP and HP lightened by 8 +/- 3 Vita tab positions, respectively, whereas group SP lightened by 5 +/- 3 tab positions (P < 0.05). At the end of the second bleaching period at day 14, group CP and HP lightened by a further 2 +/- 2 and 2 +/- 3 tab positions, respectively, whereas group SP lightened by a further 3 +/- 4 tab positions. There were no statistical differences between groups at day 14.

CONCLUSIONS

Thirty-five per cent carbamide peroxide and 35% hydrogen peroxide were equally effective for intracoronal bleaching, and significantly better than sodium perborate after 7 days. After 14 days, there were no significant differences between the groups. Thirty-five per cent carbamide peroxide can be recommended as an equally effective alternative to hydrogen peroxide for intracoronal bleaching.

Molecular markers derived from RAPD, SCAR, and the conserved 18S rDNA sequences for classification and identification in Pyrus pyrifolia and P. communis

We generated RAPD, SCAR, and conserved 18S rDNA markers for classifying and identifying cultivars of Pyrus pyrifolia (Japanese pear) and P. communis (European pear). PCR amplification with selected specific primers-LCH327UP and LCH327DOWN-was performed using DNA extracted from 25 P. pyrifolia and P. communis cultivars. The 1,380-bp fragment was amplified from P. communis cvs. Beurre Giffard, Cascade, Conference, Clapp's Favorite, Packhams Triumph, and Winter Nelis. RAPD has only a dominant single band of 1,380-bp, however, SCAR has one or more band of the same size. Amplification involving sequence-specific primer pairs LCH346UP and LCH346DOWN resulted in a loss of polymorphism. The 1,190-bp fragment was amplified from all P. pyrifolia cultivars. The conserved sequences of the 18S rDNA fragment of 25 pear cultivars were amplified and analyzed with 42 restriction enzymes. Compared with P. pyrifolia cultivars, they lacked the restriction enzyme site of KpnI and had one less RsaI site. Cultivar Gamcheonbae had a specific PstI restriction site, while cvs. Mansoo and Conference pear digested with AluI showed a different presentation than other cultivars. For the Okusankichi and Shinil pears TaqI was best marker for identification in P. pyrifolia. These results can be adopted for identifying pear cultivars; to date there is no standard marker for identifying the cultivars of fruit trees in Korean fruit tree breeding programs.

Epilepsy in Cortical Dysplasia: Factors Affecting Surgical Outcome

PURPOSE

To determine the factors influencing the outcome of cortical dysplasia resection for medically refractory epilepsy.

MATERIAL AND METHODS

13 patients underwent craniotomy for resection of epileptogenic foci using electrographic and MRI guidance. All patients had had seizures for more than 2 years and were on 3 or more antiepileptic medications. Their preoperative evaluation included MRI, neuropsychological evaluation including the WADA test, video EEG monitoring and intraoperative electrocorticography. Invasive preoperative monitoring was employed in 8 cases. The Engel outcome classification system was used. The mean follow-up time was 60.1 months with a minimum follow-up of 24 months.

RESULTS

Postoperatively, all 6 patients younger than 18 years were seizure free. Among 7 patients older than 18 years, 6 were class II and 1 was class III. Based on their preoperative MRI studies, among the patients with abnormal studies, 2 were class I, 5 were class II and 1 was class III. Among patients with normal studies, 4 were class I and 1 class II. Regarding the ictal EEG findings, among patients with localizing findings, 4 were class I and 5 were class II. Among patients with no localization in their ictal EEG, 2 were class I, 1 class II and 1 class III. Regarding the invasive preoperative monitoring of the 7 patients with localizing findings, 5 were class I and 2 were class II. The only patient with nonlocalizing findings was class II. Finally, among the patients with no invasive preoperative monitoring, 3 were class I, 1 was class II and 1 was class III.

CONCLUSION

Cortical resection is an effective treatment modality in patients with medically refractory epilepsy. In our series, the outcome was better in patients less than 18 years old and patients with normal preoperative MRI studies.

Zucchini green mottle mosaic virus is a new tobamovirus; comparison of its coat protein gene with that of kyuri green mottle mosaic virus

A novel virus we call zucchini green mottle mosaic virus (ZGMMV) was isolated from zucchini squash and its properties were determined. The size and shape of its virions, and other properties suggest that the virus is a tobamovirus. The coat protein (CP) genes of ZGMMV and kyuri green mottle mosaic virus (KGMMV), which also infects zucchini squash plants, were cloned and their nucleotides sequences were determined. The CP genes of ZGMMV and KGMMV are composed of 161 amino acid residues, and they share 77.6% amino acid identity. Western blot analysis showed that the two viruses are serologically related but not identical. Comparison of the sequences with those of sixteen other tobamoviruses revealed that the two viruses had much higher identity to cucumber green mottle mosaic virus (CGMMV), another tobamovirus infectious to cucurbit plants, than other tobamoviruses. The nucleotide and amino acid sequences of ZGMMV were from 29.5 to 78.4% and from 29.3 to 77.6% identical, respectively, to those of other tobamoviruses. The predicted virion assembly origins of the two tobamoviruses were located in the CP region of the genomic RNAs, and the predicted secondary structures were more similar to that of CGMMV than those of other tobamoviruses. The seventeen tobamo-viruses could be classified into three main subgroups based on the phylogenetic tree analysis on the CP gene, and ZGMMV and KGMMV formed a third subgroup together with CGMMV and sunn-hemp mosaic virus (SHMV). These results show that ZGMMV is a previously unknown member of the Tobamovirus genus.

Predictors of Patient Inability to Cooperate during Intraoperative Language Mapping

We examined the demographic, seizure history, personality, and intellectual variables in seizure surgery patients who underwent intraoperative language mapping to identify variables that may help predict inability to cooperate with intraoperative mapping. Of 26 patients who had intraoperative language testing during left hemisphere lobectomy, 9 were unable to cooperate with language mapping procedures. Mapping "failure" consisted of an inability to conform to task demands due to anxiety, inattention, immaturity, or confusion that necessitated changing from local to general endotracheal anesthesia. Patients who were unable to cooperate with intraoperative mapping had significantly lower IQs, lower educational attainment, and higher Depression scale scores on the Minnesota Multiphasic Personality Inventory (MMPI) relative to cooperative patients. There were no statistically significant differences between groups with respect to age, handedness, sex, age of onset of habitual seizures, seizure type, site of seizure focus, presence of a lesion, or previous psychiatric history.

Anosognosia and asomatognosia during intracarotid amobarbital inactivation

BACKGROUND

Anosognosia (i.e., denial of hemiparesis) and asomatognosia (i.e., inability to recognize the affected limb as one's own) occur more frequently with right cerebral lesions. However, the incidence, relative recovery, and underlying mechanisms remain unclear.

METHODS

Anosognosia and asomatognosia were examined in 62 patients undergoing the intracarotid amobarbital procedure as part of their preoperative evaluation for epilepsy surgery. Additional questions were asked in the last 32 patients studied.

RESULTS

During inactivation of the non-language-dominant cerebral hemisphere, 88% of the 62 patients were unaware of their paralysis, and 82% could not recognize their own hand at some point. Only 3% did not exhibit anosognosia or asomatognosia. In general, asomatognosia resolved earlier than anosognosia. When patients could not recognize their hand, they uniformly thought that it was someone else's hand. Dissociations in awareness were seen in the second series of 32 patients. Although 23 patients (72%) thought that both arms were in the air, 31% pointed to the correct position of the paralyzed arm on the table. Despite the inability of 24 of 32 patients (75%) to recognize their own hand, 21% of these patients were aware that their arm was weak, and 38% had correctly located their paralyzed arm on the angiography table.

CONCLUSIONS

Anosognosia and asomatognosia are both common during acute dysfunction of the non-language-dominant cerebral hemisphere. Dissociations of perception of location, weakness, and ownership of the affected limb are frequent, as are misperceptions of location and body part identity. The dissociations suggest that multiple mechanisms are involved.

A 13-year experience with epilepsy surgery

Between 1985 and 1997, 563 therapeutic craniotomies were performed: 311 anterior temporal (ATL) and 158 extramesial temporal (XMT) resections, 67 callosotomies, 20 hemispherectomies and 7 multiple subpial transections. Sixty-seven percent of nonlesional ATL cases were seizure free (SF), and 76% of nonlesional ATL cases < or =18 years old were SF. Seventy-eight percent of lesional ATL cases with complete resection were SF. Seventy-three percent of lesional cases < or =18 were SF. Thirty-seven percent of nonlesional XMT cases were SF. Seventy percent of XMT lesional cases with complete resection were SF, and 82% of lesional XMT cases < or =18 were SF. Of the anterior callosotomy cases, there was a > or =90% decrease in generalized tonic-clonic seizures in 50% of patients, and in tonic seizures, drop attacks, absence and myoclonic seizures in approximately 60-70% of patients. Of 20 hemispherectomies, 65% were SF. Of 7 multiple subpial transections, 29% were SF.

Self-perceived exertion level and objective evaluation of neuromuscular fatigue in a training session of orchestral violin players

The aim of the study was to investigate the self-perceived exertion level and an objective measurement of muscle fatigue on violin players before and after a training session. Fourteen professional violin players volunteered in this study. Surveillance study was used to investigate the demographic characteristics, instrument playing background, playing habits variables and factors associated with playing-related musculoskeletal complaints (PRMCs). The subjective rating of the training-induced exertion was evaluated by the Borg scale ratings of perceived exertion (RPE). Surface electromyography (EMG) was used to record the fatigue level of the upper trapezius muscles before and after a training session. Medium frequency (MF) of the EMG signals was used to document the fatigue rate of this muscle. Descriptive statistics revealed a 79% prevalence rate of PRMCs with neck and shoulder region accounting for 57.1% of the areas reported. On the self-perceived exertion level associated with the training session, results indicated a significant increase in fatigue level (p = 0.003) after the training session. Regression analysis and paired samples t-tests revealed no significant difference in the slopes of MF on both sides of trapezius muscle, before and after the training sessions. The disparity in the subjective perception with the objective findings indicated that the violinists' self-perceived exertion arises from multiple sources. The high prevalence of PRMCs in this profession warrants further ergonomic investigation of possible work-related risk factors.

The Memory Assessment Scales and lateralized temporal lobe epilepsy

We report Memory Assessment Scales (MAS) performance in 101 patients with unilateral temporal lobe epilepsy (TLE; left, n = 51; right, n = 50) with left cerebral language dominance. A significant multivariate group effect was present for the major summary indices (Verbal Memory, Visual Memory, and Global Memory, p < .04). Univariate analyses revealed no significant differences for either the Global Memory or Verbal Memory summary scores, although a significant group difference was present for Visual Memory (p < .04). The Verbal Memory-Visual Memory discrepancy score was significantly different between right and left TLE groups (p < .004). Verbal Memory scores were at least 14 points lower than Visual Memory scores in 34 patients (left = 20, 59%; right = 14, 41%). Visual Memory scores were at least 14 points lower than Verbal Memory performance in 20 patients (left = 5, 25%; right = 15, 75%). Diagnostic efficiency statistics show higher sensitivity but lower specificity in group classification for left TLE patients. These data suggest that the MAS is sensitive to material-specific memory deficits associated with a unilateral temporal lobe seizure focus. However, over one-third of the patients (19/54) with at least a 14-point Verbal Memory-Visual Memory discrepancy were classified incorrectly. The MAS, like other material-specific memory measures, should be interpreted within the context of other clinical findings.

Achilles tendon rupture repair: biomechanical comparison of the triple bundle technique versus the Krakow locking loop technique

This study was designed to compare the tensile strength of ruptured Achilles tendons repaired using either the triple bundle technique or the Krakow locking loop technique. Eight pairs of fresh frozen cadaveric Achilles tendons were harvested. A simulated "Achilles tendon rupture" was created 4 cm from the calcaneal insertion in all sixteen tendons by transversely cutting the tendon with a scalpel. One Achilles tendon "rupture" of a pair was repaired using the triple bundle technique, while the other tendon of the pair was repaired using the Krakow locking loop technique. Then, using a servohydraulic testing machine, each tendon was tested to failure in tension at a displacement rate of 2.54 cm/sec. The average rupture load for the triple bundle technique was 453 N (range 397 n 549 N), while the average rupture load for the Krakow locking loop technique was 161 N (range 121 n 216 N). This difference in averages represents a statistically significant superiority of 2.8 to 1 (p < 0.001) in favor of the triple bundle technique.

Intraocular pressure variation following retrobulbar anaesthesia among the different sex, age and ethnic groups in Malaysia

A total of 114 patients (48 Chinese, 34 Malay and 32 Indian) undergoing extracapsular cataract extraction (ECCE) with intraocular lens implantation, were enrolled. All were given 3 ml of local anaesthetic (combination of equal amounts of lignocaine 2% and bupivacaine 0.5%) using retrobulbar technique. Intraocular pressure (IOP) was measured at different time intervals; before, immediately after and 5 minutes after injection with Honan balloon compression. Mean IOP increased by 5.0 mmHg immediately after injection (p < 0.001) and reduced to baseline level after 5 minutes of external compression. Although there were no statistical difference in terms of IOP variation between sex and age groups, Chinese patients demonstrated the highest IOP rise following retrobulbar anaesthesia. This is the first study to demonstrate the influence of race in the IOP response with Chinese subjects having the highest IOP rise.

Recognition of facial emotion in nine individuals with bilateral amygdala damage

Findings from several case studies have shown that bilateral amygdala damage impairs recognition of emotions in facial expressions, especially fear. However, one study did not find such an impairment, and, in general, comparison across studies has been made difficult because of the different stimuli and tasks employed. In a collaborative study to facilitate such comparisons, we report here the recognition of emotional facial expressions in nine subjects with bilateral amygdala damage, using a sensitive and quantitative assessment. Compared to controls, the subjects as a group were significantly impaired in recognizing fear, although individual performances ranged from severely impaired to essentially normal. Most subjects were impaired on several negative emotions in addition to fear, but no subject was impaired in recognizing happy expressions. An analysis of response consistency showed that impaired recognition of fear could not be attributed simply to mistaking fear for another emotion. While it remains unclear why some subjects with amygdala damage included here are not impaired on our task, the results overall are consistent with the idea that the amygdala plays an important role in triggering knowledge related to threat and danger signaled by facial expressions.

Effects of anomalous language representation on neuropsychological performance in temporal lobe epilepsy

OBJECTIVE

To examine the effects of anomalous language representation (i.e., mixed- and right-cerebral dominant) on neuropsychological performance.

BACKGROUND

Right cerebral language dominance resulting from early cerebral injury is associated with relatively preserved language function with decreased visuospatial ability. However, previous reports of this phenomenon have examined patients with relatively large cerebral injuries (e.g., infantile hemiplegia) or limited sample sizes.

METHODS

A total of 561 patients with complex partial seizures of left temporal lobe origin were studied. Patients were classified into left (n = 455), bilateral (n = 58), and right (n = 48) language dominant groups based on Wada testing.

RESULTS

Right language dominant patients performed more poorly on multiple tests of visuospatial function, including Performance IQ (PIQ), than did left language patients. No significant group differences were detected for measures of language or general verbal function. The effects of bilateral language on PIQ differed according to handedness. Lowered PIQ was present in the bilateral nondextral group but not for bilateral dextral patients, and this pattern was observed with other visuospatial measures.

CONCLUSIONS

In patients with relatively small lesions restricted to the left mesial temporal lobe, a shift in language dominance to the right hemisphere is associated with decreased visuospatial functions but preserved verbal abilities. Nondextral patients with bilateral language representation also displayed decreased visuospatial performance, although dextral patients with bilateral language did not.

Different contributions of the human amygdala and ventromedial prefrontal cortex to decision-making

The somatic marker hypothesis proposes that decision-making is a process that depends on emotion. Studies have shown that damage of the ventromedial prefrontal (VMF) cortex precludes the ability to use somatic (emotional) signals that are necessary for guiding decisions in the advantageous direction. However, given the role of the amygdala in emotional processing, we asked whether amygdala damage also would interfere with decision-making. Furthermore, we asked whether there might be a difference between the roles that the amygdala and VMF cortex play in decision-making. To address these two questions, we studied a group of patients with bilateral amygdala, but not VMF, damage and a group of patients with bilateral VMF, but not amygdala, damage. We used the "gambling task" to measure decision-making performance and electrodermal activity (skin conductance responses, SCR) as an index of somatic state activation. All patients, those with amygdala damage as well as those with VMF damage, were (1) impaired on the gambling task and (2) unable to develop anticipatory SCRs while they pondered risky choices. However, VMF patients were able to generate SCRs when they received a reward or a punishment (play money), whereas amygdala patients failed to do so. In a Pavlovian conditioning experiment the VMF patients acquired a conditioned SCR to visual stimuli paired with an aversive loud sound, whereas amygdala patients failed to do so. The results suggest that amygdala damage is associated with impairment in decision-making and that the roles played by the amygdala and VMF in decision-making are different.

Time perception following unilateral amobarbital injection in patients with temporal lobe epilepsy

Estimates of elapsed time were obtained from 53 patients with unilateral temporal lobe epilepsy (Left TLE = 27; Right TLE = 26) following Wada (intracarotid amobarbital) assessment. After resolution of drug effects, patients were asked to estimate how much time had passed since amobarbital administration. Estimates were also obtained from 24 healthy control subjects using the same cognitive tasks over a similar time frame. Elapsed time was significantly underestimated by both left and right TLE groups following right hemisphere injection. In addition, there was an interaction effect involving patient group, side of injection, and sequence of injection. Left TLE patients, consistent with normal controls, made more accurate time estimates when they could anticipate the estimation task following the second amobarbital administration. More accurate time estimates, however, occurred only when left hemisphere injection was second in sequence. In contrast, right TLE patients did not improve regardless of the order of injection. These results suggest that right hemisphere function plays a critical role in the accuracy of time estimations of intermediate temporal duration and that interhemispheric interaction may be required to make accurate retrospective temporal judgments. These findings are discussed in the context of the growing evidence for a right-hemispheric attentional network.

Clinical and physiological effects of stereotaxic bilateral amygdalotomy for intractable aggression

The amygdala is thought to be an important neural structure underlying the "fight-or-flight" response, but information on its role in humans is scarce. The clinical and psychophysiological effects of amygdalar destruction were studied in 2 patients who underwent bilateral amygdalotomy for intractable aggression. After surgery, both patients showed a reduction in autonomic arousal levels to stressful stimuli and in the number of aggressive outbursts, although both patients continued to have difficulty controlling aggression. The "taming effect" reported after bilateral amygdalar destruction may be due to the amygdala's inadequate processing of perceived threat stimuli that would normally produce a fight-or-flight response.

Results of lesional vs. nonlesional frontal lobe epilepsy surgery

Fifty-three seizure focus resections limited to the frontal lobe were performed. Forty-nine had adequate follow-up. Five of 17 (29%) nonlesional (NL) cases and 21 of 32 (66%) lesional (L) cases were seizure free (SF) at 1 year postoperatively. Eight of 9 (89%) L cases < or = 18 years old vs. 13 of 23 (57%) > 18 years old were SF. Eight of 10 (80%) tumor vs. 13 of 22 (59%) nontumor L cases were SF. Sixteen NL cases were localized by invasive recording. Five (31%) were SF. Ictal localization was obtained in 4 of 32 L cases. Three of 4 (75%) were SF. Eighteen of 24 (64%) L cases without ictal localization were SF. Nine of 12 (75%) lateral resections, 7 of 12 (58%) lobectomies, and 2 of 13 (15%) mesial resections were SF. Three of 20 cases with at least 90% reduction in seizures became SD > or = 2 years postresection. No case with < 90% seizure reduction at one year showed improvement with longer follow-up.

Wada memory and timing of stimulus presentation

We compared Wada memory performance for stimuli presented at two timing intervals following amobarbital injection in 47 non-lesional patients with complex partial seizures (L = 26; R = 21). A significant interaction between seizure focus and timing of presentation was present (P < 0.03). Memory performance for objects whose presentation began approximately 50-55 s following amobarbital administration differed as a function of ipsilateral vs. contralateral injection at a very high level of statistical significance (P < 0.00001). Items presented approximately 4 min, 30 s post injection were also related to seizure onset literality, but at a lower statistical level (P < 0.01). Presentation of Wada memory stimuli earlier during hemispheric anaesthesia yields results that are more sensitive to lateralized temporal lobe seizure onset than does presentation of items later during the procedure.

Level of consciousness and memory during the intracarotid sodium amobarbital procedure

Controversy exists regarding differential effects on consciousness of left/right cerebral inactivation via intracarotid amobarbital. Further, the effects of level of consciousness (LOC) on memory during the intracarotid sodium amobarbital procedure (IAP) are unclear. A modified version of the Glasgow Coma Scale altered to avoid the confounding effects of aphasia was employed to assess LOC in 97 patients during the IAP. A greater impairment in LOC occurred with left cerebral inactivation. Memory was more impaired following left hemisphere injections as well as from injections contralateral to seizure focus. Memory was correlated with LOC, and this effect was more prominent for right hemisphere injections and for injections ipsilateral to seizure focus. These findings support differential cerebral roles in consciousness and demonstrate that IAP memory performance may be affected by the patient's LOC.

Effect of Wada memory stimulus type in discriminating lateralized temporal lobe impairment

PURPOSE

To examine the effects of memory stimulus type on Wada memory performance.

METHOD

Ninety-six patients (left, 47; right, 49) from four epilepsy centers who were candidates for anterior temporal lobectomy (ATL) and who have subsequently undergone surgery were studied. Patients with atypical cerebral language lateralization or with evidence on magnetic resonance imaging (MRI) to suggest a lesion other than hippocampal sclerosis were excluded. Wada memory performance was obtained by using both real objects and line drawings as memory stimuli.

RESULTS

Wada memory laterality scores with either real objects or line drawings as memory stimuli discriminated left from right-ATL groups. However, objects were superior to line drawings in making this differentiation. Further, objects were superior to line drawings in individual patient classification of candidates for left ATL, with no difference in the classification rates using either objects or line drawings in candidates for right ATL.

CONCLUSIONS

Type of memory stimuli is an important factor affecting memory results during the Wada test.

Amobarbital evaluation of neurobehavioral function prior to therapeutic occlusion of brain arteriovenous malformations: a new neuropsychological procedure

Because untreated arteriovenous malformations (AVMs) frequently result in some form of permanent neurological complication, treatment of AVMs is aggressively pursued A relatively new treatment consists of sending micropellets into blood vessels supplying the AVM core to block blood flow and "shrink" the AVM When vessels supplying the AVM are thought to also irrigate vital portions of brain, evaluations of neurobehavioral function after injection of amobarbital into intracranial vessels (Wada testing) may be performed to prevent significant complications folIowing embolization This study details our preliminary experience with Wada testing and electroencephalography (EEG) prior to AVM embolization in seven patients Neurobehavioral functions were continuously monitored after injection of 50-75 mg of amobarbital into target cerebral vessels No change in sensorimotor, cognitive, or EEG functions were detected in any of the superselective Wada examinations Embolization was performed following all negative Wada evaluations The only irreversible complication after embolization was a superior quadrantanopia No other permanent neurobehavioral sequelae resulted from embolization These preliminary findings suggest that simultaneous Wada/EEG monitoring may be useful in predicting neurobehavioral complications prior to AVM embolization.

Intraoperative hippocampal cooling and Wada memory testing in the evaluation of amnesia risk following anterior temporal lobectomy

OBJECTIVE

To determine the efficacy of memory testing following localized thermal inactivation (cooling) of the hippocampus during epilepsy surgery to assess risk for postoperative memory decline.

DESIGN

Memory was assessed after intraoperative thermal inactivation of the hippocampus and during the Wada procedure to help determine the clinical utility of each procedure.

SETTING

A university hospital, comprehensive epilepsy surgery program.

PATIENTS

Individuals undergoing unilateral temporal lobectomy for relief of intractable seizures.

PROCEDURE

After temporal tip resection, iced liquid was irrigated into the temporal horn of the lateral ventricle until the hippocampus was "cooled."

MAIN OUTCOME MEASURES

Multiple neuropsychological measures of learning and memory.

RESULTS

Wada memory testing suggested risk for memory impairment in 15 patients while cooling indicated risk in only five patients. Predictions arising from the two procedures were concordant in 13 patients and discordant in 12 patients. Among the 12 inconsistent predictions, hippocampal cooling suggested adequate contralateral memory support in 11 (92%) of 12 patients, and none of these 11 patients had a postoperative anterograde amnesia.

CONCLUSION

Intraoperative hippocampal cooling may be useful in determining the risk of postoperative memory disorder among selected patients undergoing epilepsy surgery.

Intraoperative thermal inactivation of the hippocampus in an effort to prevent global amnesia after temporal lobectomy

In an effort to assess the risk of amnesia after anterior temporal lobectomy (ATL), we conducted localized thermal inactivation (cooling) of the hippocampus with memory testing. Thirty-three ATL patients whose preoperative evaluation suggested risk for postoperative amnesia underwent hippocampal cooling. Cooling consisted of inserting a catheter in the temporal horn and irrigating it with an iced solution until a stable hippocampal temperature of approximately 20 degrees C was reached. Memory was assessed before and after cooling. In 12 of the 33 patients, memory testing was either aborted or suggested poor contralateral support, and the hippocampus was resected in 2 of these patients. The remaining 21 patients showed evidence of contralateral memory support, and the hippocampus was resected in 18. No patient became amnestic. These results suggest that intraoperative hippocampal cooling may be useful in selected cases. However, even among many patients who could cooperate with testing, discomfort, sedation, attentional deficits, confusion, and anxiety made test interpretation difficult.

Wada memory asymmetries predict verbal memory decline after anterior temporal lobectomy

We examined Wada memory and neuropsychological memory function in 34 nonlesional patients who underwent anterior temporal lobectomy (ATL) and who were seizure free at 1-year follow-up. Patients who displayed a decline on verbal memory measures that exceeded 1 SD after left ATL had significantly smaller left/right Wada memory asymmetries than left ATL patients without a significant verbal memory decline. When Wada memory asymmetries were used to predict verbal memory decline after left ATL in individual patients, similar statistically significant effects were present. No significant relationship between Wada memory and postoperative memory was present in right ATL patients, and postoperative memory function was not related to Wada memory performance after either left hemisphere or right hemisphere injection alone. We conclude that Wada memory asymmetries provide one measure of the risk to material-specific decline in verbal memory after left ATL.

Effects of anticonvulsant therapy on recovery and rehabilitation

Antiepileptic drugs (AEDs) are used in rehabilitation patients with injury to the nervous system for control of clinical seizures, prophylaxis against the development of a seizure disorder, and treatment of secondary mania. Although most AEDs can produce mild cognitive side effects, the benefits of treatment with AEDs in rehabilitation patients with seizure disorders typically outweigh these minor risks, Bromide, phenobarbital, and benzodiazepines may have more severe cognitive side effects than other AEDs. However, there is no convincing evidence of clinically significant differences in cognitive adverse effects among the other established AEDs. Furthermore, cognitive side effects are usually modest with mono therapy and anticonvulsant blood levels within standard therapeutic ranges. With regard to prophylaxis against future seizures, there is no significant data indicating that AED administration can prevent or retard the process of epileptogenesis, Therefore, the use of AEDs to prevent the development of a seizure disorder is not warranted at this time. Finally, although there is little information about the behavioral effects of anticonvulsants in neurological rehabilitation patients, the efficacy of carbamazepine, and perhaps valproate, in the treatment of primary mania suggests that these AEDs may be beneficial in mania secondary to brain injury. The role of AEDs in the treatment of other psychiatric disorders, such as post-traumatic stress disorder and episodic dyscontrol, remains unclear.

Wada memory performance predicts seizure outcome following anterior temporal lobectomy

We examined the ability of Wada memory testing to predict seizure outcome 1 year following anterior temporal lobectomy. Asymmetry scores for Wada memory performance, using amobarbital doses of 125 mg or less, were calculated for 55 patients under the age of 45 years who had no radiologic evidence of structural lesions other than gliosis. Wada memory asymmetries were significantly greater (p < 0.02) in patients who were seizure free compared with those who continued to experience seizures. Furthermore, patients with Wada memory score asymmetries of at least three objects (maximum = 8) were more likely to be seizure free compared with patients with Wada memory asymmetries less than three (p < 0.01). Of the 36 patients who had Wada memory score asymmetries of at least three objects, 32 (89%) were seizure free. In contrast, of the 19 patients whose Wada memory score asymmetries were less than three, only 12 (63%) were seizure free. These data suggest that Wada memory performance is related to seizure outcome following anterior temporal lobectomy.

Do dichotic word listening asymmetries predict side of temporal lobe seizure onset?

Dichotic word listening asymmetries are thought to be useful in predicting side of temporal lobe dysfunction. However, little direct evidence exists to support this assumption in practice, especially in patients with subtle epileptogenic lesions. To determine if word listening ear asymmetries are valid predictors of side of temporal lobe seizure onset, we examined the preoperative dichotic word listening performance of 80 patients with either left (N = 41) or right (N = 39) temporal lobe (TL) seizure foci. On a group level, patients showed a statistically significant 'lesion effect' as evidenced by a relative deficit in the ear contralateral to the side of lesion. Prediction of side of seizure focus in individual cases, however, was poor: depending upon the criteria used, 61% to 80% of epileptics with unilateral temporal lobe foci did not show the expected contralateral ear deficit. Results suggest that caution be exercised when inferring side of temporal lobe seizure focus through dichotic word listening asymmetries in individual temporal lobe epilepsy cases.

Stimulus timing effects on Wada memory testing

OBJECTIVE

To determine the effects of presenting Wada memory stimuli at different times after intracarotid amobarbital injection on Wada memory asymmetries.

DESIGN

Wada memory asymmetries from three timing series were related to the laterality of eventual temporal lobectomy.

SETTING

Academic institution epilepsy surgery program.

PATIENTS

Forty-three patients with complex partial seizures who later underwent anterior temporal lobectomy (left temporal lobectomy, 24 patients; right temporal lobectomy, 19 patients). No patient included had abnormalities on magnetic resonance imaging scans to suggest a lesion other than gliosis.

RESULTS

Memory performance for objects whose presentation began approximately 45 seconds after amobarbital administration differentiated laterality of seizure onset. Memory for items presented later and after partial return of language (on average 3 minutes 40 seconds postinjection) also differed as a function of ipsilateral vs contralateral injection, but at a lower level of statistical significance. Memory for items presented last during the procedure (on average 6 minutes postinjection) discriminated seizure groups at a still lower level of statistical significance. When used to predict lateralized temporal lobe impairment in individual patients, early object memory performance was significantly better than memory performance employing either middle (56%) or late (43%) stimulus presentation timings.

CONCLUSION

The results of early object memory testing are superior to those obtained from stimulus presentation later in the procedure in documenting temporal lobe dysfunction associated with a lateralized seizure onset.

Amnesia after unilateral temporal lobectomy: a case report

We report a mixed handed (L > R) patient with exclusive right cerebral language representation who developed a permanent anterograde amnestic syndrome after right anterotemporal lobectomy. Preoperative neuropsychological performance consisted of impaired verbal memory and normal nonverbal memory. Wada memory performance was asymmetrical for objects presented soon after amobarbital injection in conjunction with no memory asymmetry for items presented later in the Wada evaluation. Pre- and postoperative magnetic resonance imaging (MRI) scans showed no structural lesions; however, postoperative MRI hippocampal volume measurements suggested decreased hippocampal volume for the nonresected temporal lobe. These results confirm the risk of anterograde amnesia after unilateral temporal lobectomy and demonstrate that baseline neuropsychological testing may falsely literalize material-specific memory functions in patients with atypical cerebral language dominance.

Effects of temporal lobectomy on generative fluency and other language functions

We investigated the acute effects of unilateral temporal lobectomy on multiple language measures and standardized generative word fluency tasks, as well as longer term effects measured 1 year following surgery. All patients were left cerebral dominant for language functioning as determined by Wada testing. Results indicate consistent acute language decline for left but not right temporal lobectomy patients. In contrast, verbal generative fluency decreased independent of lesion laterality, suggesting diffuse acute lesion effects on certain tasks mediated primarily by the left hemisphere. When examining language performance in an independent patient group at their 1-year follow-up assessment, no negative surgery effects were present on any language measure. Further, significant improvement over baseline performance for word fluency was present 1 year following surgery. In the acute assessment of cognition following temporal lobectomy, the relative sensitivity of neuropsychological measures to acute cerebral lesions should be considered.

Influence of premorbid personality and location of lesion on emotional expression

Both premorbid personality characteristics and location of brain lesion have been proposed to account for emotional changes after cerebral damage. To explore the relative merits of each hypothesis, we compared the MMPI profiles of 30 epileptic patients, who showed either a euphoric or depressive reaction after injection of amobarbital into the right or left hemisphere, with the MMPI profiles of 30 matched controls. There were no significant T-score differences between euphoric, depressed, or control patients on any of the MMPI scales. However, more patients with euphoric (42%) than depressed (0%) reactions had hypomania (scale 9) scores greater than 70 T. With regard to location of lesion, there was a statistically significant association between emotional reaction and side of amobarbital brain inactivation. Euphoria was more frequent following right, and depression was more common after left, hemisphere inactivation. Although support was found for both premorbid personality and lesion location in the genesis of emotional reactions after brain damage, results were more robust for location of lesion.

Wada memory testing and hippocampal volume measurements in the evaluation for temporal lobectomy

We examined the relationship of Wada memory performance and MRI hippocampal volume measurements to laterality of ultimate seizure localization in 20 patients with complex partial seizures who later underwent temporal lobectomy. Discriminant function analysis employing both Wada memory test asymmetries and hippocampal volume asymmetries correctly classified 100% of the patients into left and right temporal lobe groups. Wada memory asymmetries alone correctly classified 90% of the sample (80% of the sample when the discriminant function included all patients except the one being classified), and hippocampal volume asymmetries alone correctly classified 90% of the patients. A significant correlation was present between Wada memory asymmetries and hippocampal volume asymmetries (r = 0.78), indicating that structural evidence of reduced hippocampal volume has a functional correlate reflected by Wada memory performance. These data suggest that the combination of functional and structural measures is of value in the preoperative evaluation for epilepsy surgery.

The phenomenology of multiple partial seizure-like symptoms without stereotyped spells: an epilepsy spectrum disorder?

Consistent with previous reports by neuropsychiatrists, the results of the present investigation confirmed the existence of a neurobehavioral disorder characterized by the subjective experiencing of multiple cognitive, affective, and psychosensory phenomena similar to those associated with more classic partial seizure disorders. According to the literature, such patients typically respond favorably to anticonvulsants although they lack the customary motor manifestations of complex partial seizure (CPS) disorders and typically do not have stereotyped spells. This neuropsychiatric syndrome has recently been termed epilepsy spectrum disorder (ESD). In the present study, 30 patients with ESD were matched with equal numbers of treatment-refractory CPS patients and normal controls. All subjects were administered a standardized interview consisting of 35 cognitive, affective, and psychosensory partial seizure-like symptoms. The results indicated that ESD patients endorsed significantly more partial seizure-like symptoms than did CPS patients and controls. Relatively low levels of symptom endorsement by an unmatched psychiatric comparison sample indicated that the high levels of symptom endorsement by ESD patients could not be attributed to the presence of psychiatric dysfunction per se. Analysis of responding to 'foil' items unrelated to partial seizures indicated that high levels of symptom endorsement by ESD patients did not merely reflect a deviant response. Although ESD patients seldom present themselves at tertiary care epilepsy centers, the study of such patients is likely to be of relevance to mainstream epileptology.

Differential effects of left versus right seizure focus on human hippocampal evoked responses

Hippocampal evoked potentials were recorded using the P3 tonal oddball paradigm in 30 patients with unilateral temporal lobe seizure focus. Spectral power of the evoked potentials was decreased on the side of seizure focus, but this reduction was much greater when the focus was on the left. The effect of left/right focus does not appear to be due to group differences in age, sex, seizure duration, or operative pathology. Remote or finer left/right structural differences or differential left/right hippocampal processing for the sequential tonal task are possible explanations.

Reproducibility of P3

The P3 event-related potential has been widely employed in both clinical and research investigations. In the present study, P3 latency and amplitude intersession reliability were evaluated in 4 sessions over an average of 33 days in 24 healthy adults using the P3 tonal oddball paradigm. Mean group latencies ranged from 302-305 ms and mean amplitudes ranged from 7.75-8.87 microV. No significant group differences were found across sessions for latency or amplitude. Intrasubject variability was large; the 95% confidence interval for the difference between the means of two combined sessions was +/- 20 ms for latency and +/- 4.63 microV for amplitude. The results suggest that P3 latency and amplitude are reliable and reproducible over weeks for groups, but have greater variability for individuals.

Hippocampal contribution to verbal recent memory following dominant-hemisphere temporal lobectomy

The effects of hippocampal encroachment in the language dominant-hemisphere were studied in 41 patients who underwent previous temporal lobectomy (TL). Patients undergoing dominant-hemisphere TL including anterior hippocampus (n = 13) performed significantly worse than nondominant TL patients (n = 16) on a verbal learning test (Selective Reminding; p less than or equal to .00001), thereby confirming the sensitivity of this procedure to lateralized temporal-lobe dysfunction. However, no significant difference was present on this or other primary measures of material-specific memory when contrasting dominant TL patients in whom the anterior hippocampus was spared (n = 12) to those in whom anterior hippocampus was resected. These data suggest that more extensive and posterior mesial temporal-lobe resection is not necessarily associated with a greater verbal material-specific memory deficit following dominant-hemisphere temporal lobectomy.

Behavioral state-specific changes in human hippocampal theta activity

Although there has been extensive examination of the behavioral and physiologic correlates of hippocampal theta activity in animals, the human literature consists of a single case study. We investigated the differential effects of four behavioral states on human hippocampal theta activity in 16 epilepsy surgery patients. Behavioral conditions included resting eyes closed (RC), resting eyes open (RO), eyes open with auditory word activation (AW), and eyes open with visuospatial activation (VS). Hippocampal theta activity decreased during both RO and VS compared to both RC and AW. There were reciprocal changes in delta activity. Comparisons of RO to VS and of RC to AW were nonsignificant. The results demonstrate state-specific changes in human hippocampal theta and are consistent with the animal literature that relates hippocampal theta to sensorimotor integration and forebrain volitional mechanisms.

Three-dimensional structure of Cu,Zn-superoxide dismutase from spinach at 2.0 A resolution

The three-dimensional structure of Cu,Zn-superoxide dismutase from spinach leaves has been determined by X-ray crystal structure analysis. The atomic coordinates were refined at 2.0 A resolution using the Hendrickson and Konnert program for stereochemically restrained refinement against structure factors, which allowed the use of non-crystallographic symmetry. The crystallographic residual error for the refined model was 24.9%, with a root mean square deviation of 0.03 A from the ideal bond length and an average atomic temperature factor of 9.6 A. A dimeric molecule of the enzyme is comprised of two identical subunits related by a non-crystallographic 2-fold axis. Each subunit of 154 amino acid residues is composed primarily of eight anti-parallel beta-strands that form a flattened cylinder, plus three external loops. The main-chain hydrogen bonds primarily link the beta-strands. The overall structure of this enzyme is quite similar to that of the bovine dismutase except for some parts. The single disulfide bridge (Cys57-Cys146) and the salt bridge (Arg79-Asp101) may stabilize the loop regions of the structure. The Cu2+ and Zn2+ ions in the active site lie 6.1 A apart at the bottom of the long channel. The Cu2+ ligands (ND1 of His-46, and NE2 of His-48, -63, and -120) show an uneven tetrahedral distortion from a square plane. The Zn2+ ligands (ND1 of His-63, -71, and -80 and OD1 of Asp-83) show an almost tetrahedral geometry. The imidazole ring of His-63 forms a bridge between the Cu2+ and Zn2+ ions.(ABSTRACT TRUNCATED AT 250 WORDS)

Constructional praxis performance of Japanese and American, normal and brain-damaged patients

Numerous studies have suggested population differences between Japanese and Americans concerning various cognitive functions. Transcultural differences in spatial reasoning, language, and dominance for emotional expression raise important questions concerning current conceptions of hemispheric cerebral dominance for cognitive functioning. If cultural differences in cognition exist, learning may play a greater role in determining laleralizalion of cognitive functions than is presently accepted. To investigate these issues, we initiated two collaborative studies comparing Japanese with American normals and brain-damaged patients on the Three-Dimensional Constructional Praxis Test. In normal subjects, there were no significant differences between the two cultures in the distribution of visuoconstructive ability. In patients with brain damage, the effects of unilateral brain lesions and their neuropsychological consequences on visuoconstructive ability were similar in both cultures. Thus, there are no apparent differences between the Japanese and American peoples in visuoconstructive abilities, or in the underlying cerebral organization of skills required to execute these functions.

Material specific learning during electrical stimulation of the human hippocampus

Material specific learning was assessed during unilateral electrical stimulation of the hippocampus through intracerebrally implanted electrodes in 30 patients with unilateral temporal lobe epilepsy (TLE). Verbal learning significantly decreased in patients with right TLE after stimulation of the left, but not the right, hippocampus. No verbal learning impairment was observed in left TLE patients following stimulation of either hippocampus. Visuospatial memory performance significantly decreased following stimulation of the right hippocampus regardless of the side of seizure onset. Results suggest that the contralateral "nonepileptic" hippocampus does not assume the material specific mnestic functions of the dysfunctional hippocampus associated with longstanding epilepsy.