Pages Physical Medium Print-Electronic. Metadata Show full item record. Citation Pang, C. The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry, 25 2 , Abstract The hippocampus has a critical role in cognition and human memory and is one of the most studied structures in the brain.
Recent findings have shown that CA2 plays a bigger role than previously thought. Download preview PDF. Skip to main content.
Advertisement Hide. Development of afferent lamination in Ammon's horn of the rat. This is a preview of subscription content, log in to check access. Angevine JB Time of neuron origin in the hippocampal region. An autoradiographic study in the mouse. Exper Neurol, —70, Suppl.
Bayer S in press The development of the hippocampal region in the rat. Neurogenesis examined with 3 H-thymidine autoradiography. J Comp Neurol Google Scholar. Bayer SA, Altman J Hippocampal development in the rat: Cytogenesis and morphogenesis examined with autoradiography and low-level X-irradiation. Fricke R, Cowan WM An autoradiographic study of the development of the entorhinal and commissural afferents to the dentate gyrus of the rat.
Gottlieb DI, Cowan WM Evidence for a temporal factor in the occupation of available synaptic sites during the development of the dentate gyrus. Gottlieb DI, Cowan WM Autoradiographic studies of the commissural and ipsilateral association connections of the hippocampus and dentate gyrus of the rat. The commissural connections. Herkenham M The connections of the nucleus reuniens thalami: Evidence for a direct thalamo-hippocampal pathway in the rat.
Despite a certain risk of postoperative memory decline, 44 catastrophic memory outcomes after unilateral temporal lobe surgery have rarely been reported.
However, there is evidence of more severe verbal memory decline after left temporal lobe resections in patients with bilateral AHS as compared with patients with unilateral AHS 40 and significantly worse pre- and postoperative memory in comparison to patients with nonatrophied hippocampi. While 7 patients reported an improved quality of life, subjective memory was unchanged in 8 patients.
Whether subjective outcome was associated with bilateral AHS could not be derived from this study. In summary, the literature suggests that epilepsy surgery can be performed in patients with bilateral AHS if the presurgical evaluation indicates a clear preponderance of seizure onsets in 1 hemisphere.
There is no evidence that amnestic syndromes are the inevitable consequence of unilateral epilepsy surgery in patients with bilateral AHS, as it was described in the early series of patients with bilateral mesial epilepsy surgery in The degree of this memory loss, however, and the consequences of these deficits regarding everyday functioning and quality of life have yet to be determined.
To address this question, the present investigation evaluated the neuropsychological outcome of a group of patients with bilateral AHS who underwent epilepsy surgery and compared them with a group of patients with the same diagnosis who were not suited for surgery and were treated pharmacologically. The selection of surgical candidates and their seizure outcomes as compared with patients with unilateral AHS are described in detail in a previous paper.
Thirty-two patients with bilateral AHS diagnosed between January and March were selected retrospectively from the database of the epilepsy center at the University Clinic of Bonn, Germany. The diagnosis of bilateral AHS was defined by combining relaxometry elevated T2 relaxation times with a visual MRI diagnosis in terms of atrophy and signal increase 49 Fig.
flurannoopamur.tk Eleven patients had undergone epilepsy surgery after recording of seizures with hippocampal depth electrodes. The surgery consisted of selective amygdalohippocampectomy in all but 1 case, in which the temporal pole was included in the resection. Thirteen patients included in this study underwent invasive electroencephalographic EEG recording bitemporal strip and depth electrodes.
In all of these patients, seizures with hippocampal origin could be recorded.
In 2 patients, the treating physician rejected a surgical treatment because there was no clear preponderance of 1 seizure onset side. These patients were included in the nonsurgical group. The remaining 11 patients underwent surgery. All 11 surgical bilateral AHS patients had complete sets of pre- and postsurgical 1 year neuropsychological data according to the standard protocol for surgical patients. Eight of 13 nonsurgical patients with bilateral AHS met the inclusion criterion of at least 2 neuropsychological assessments and served as the control group.
Because of the retrospective design, the decision for or against surgery did not follow a specific protocol but varied among patients and treating physicians. In 4 patients, seizure frequency was tolerable so that epilepsy surgery was not indicated. In 2 patients, reasons were not described explicitly but the treating physician decided that the patient was not a good surgical candidate given the bilateral pathology.
Finally, 2 patients were implanted with intracranial electrodes but there was no clear preponderance of 1 side regarding the onset of seizures. The demographic and clinical characteristics of the patients are given in Table 1. Side of surgery 8 left vs 3 right temporal resections was not considered in the analyses due to low statistical power. The groups differed in regard to the number of antiepileptic drugs at follow-up and the retest interval—in both cases, values greater in the nonsurgical versus the surgical group—because in nonsurgical patients, reassessments are usually not provided for and were conducted during inpatient or outpatient visits, which resulted in large variations of retest intervals between 2 and 9 years.
Furthermore, the groups differed in regard to clinical characteristics because patients in the control group were not considered as surgical candidates, mostly because the pathologies in both hemispheres were equally severe. These aspects need to be taken into consideration when evaluating the results and are addressed in the discussion.
We did not seek ethical approval for conducing the study because the data were assessed in clinical practice and analyzed retrospectively. However, informed consent was obtained from the patients. Neuropsychological examination followed a standard protocol, which focused mainly on memory functions but also included executive functions, and has been described previously.
For statistical analyses, the number of remembered words in the delayed recall trial was used because it represents the total performance in this test most adequately. For the assessment of executive functions, a phonemic verbal fluency task 33 and a response inhibition task 36 were applied.
To reduce the amount of information for statistical analysis, memory as well as executive scores were merged into composite scores for both domains.
For the evaluation of significant changes of individual performance, reliable change indices RCIs based on — retested healthy subjects were applied. The patients' subjective condition was evaluated using questionnaires.
For the assessment of mood, the Beck Depression Inventory BDI 5 was applied using a score of greater than 10 points as the cutoff indicating depressed mood. Higher QOLIE scores reflect a worse quality of life, 27 and a score greater than 32 indicates a subjectively impaired quality of life.
Finally, subjectively perceived capabilities and cognition were investigated using simple ratings. In addition to items assessing problems in global functioning, orientation, concentration, attention, and memory and verbal fluency, the patients rated their memory functions 6-tiered rating scale , impairments of general performance 4-tiered rating scale , and the impact of these impairments on everyday life 4-tiered rating scale.
Questionnaires were not available for all patients and for most subjects only at follow-up, allowing no longitudinal analyses. Due to the small sample size, most variables were not normally distributed, as indicated by the Kolmogorov-Smirnov test and visual inspection of histograms. Thus, for examining group effects, the Fisher's exact test for nominal data and Mann-Whitney U-test for metric data were calculated.
Wilcoxon signed-rank tests were used for analyzing change of group scores over time. Standardized individual and group scores for the separate tasks are given in Table 2. Surgical and control patients neither differed in their baseline memory performance as a group, nor was the number of individually impaired patients significantly different.