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

Forgetting rates were examined in patients with diencephalic, temporal lobe, or frontal lesions. No significant differences were found in short-term forgetting of verbal and nonverbal material; in recognition memory for pictures, words, or designs over delays between 1 min and 20 or 30 min; or on a measure of explicit cued recall for words, calculated in terms of the process dissociation procedure. Significantly faster forgetting was found in the diencephalic and the temporal lobe groups in the free recall of pictures of objects, although there was no difference between these 2 groups. It is concluded that the major deficit in amnesic patients' memory processes is in the initial acquisition of information but that there is a subtler deficit in retention over specific delays, detectable only on measures of free recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive impairment following frontal lobe damage and its relevance to human amnesia.

Whether frontal lobe pathology can account for some of the cognitive impairment oberved in amnesic patients with Korsakoff's syndrome was investigated. Various cognitive and memory tests were given to patients with circumscribed frontal lobe lesions, patients with Korsakoff's syndrome, non-Korsakoff amnesic patients, and control Ss. Patients with frontal lobe lesions were not amnesic. Nevertheless, they exhibited 2 deficits that were also exhibited by patients with Korsakoff's syndrome but not by other amnesic patients: (a) impairment on the Wisconsin Card Sorting Test and (b) impairment on the Initiation and Perseveration subscale of the Dementia Rating Scale. Thus, frontal lobe pathology can explain some of the cognitive deficits observed in patients with Korsakoff's syndrome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amygdala damage in experimental and human temporal lobe epilepsy

The amygdala complex is one component of the temporal lobe that may be damaged unilaterally or bilaterally in children and adults with temporal lobe epilepsy (TLE) or following status epilepticus. Most MR (magnetic resonance) imaging studies of epileptic patients have shown that volume reduction of the amygdala ranges from 10-30%. In the human amygdala, neuronal loss and gliosis have been reported in the lateral and basal nuclei. Studies in rats have more specifically identified the amygdaloid regions that are sensitive to status epilepticus-induced neuronal damage. These areas include the medial division of the lateral nucleus, the parvicellular division of the basal nucleus, the accessory basal nucleus, the posterior cortical nucleus, and portions of the anterior cortical and medial nuclei. Otherwise, other amygdala nuclei, such as the magnocellular and intermediate divisions of the basal nucleus and the central nucleus, remain relatively well preserved. Amygdala kindling studies in rats have shown that the density of a subpopulation of GABAergic inhibitory neurons that also contain somatostatin may be reduced even after a low number of generalized seizures. While analyses of histological sections and MR images indicate that in approximately 10% of TLE patients, seizure-induced damage is isolated to the amygdala, more often amygdala damage is combined with damage to the hippocampus and/or other brain areas. Moreover, recent data from rodents and nonhuman primates suggest that structural and functional alterations caused by seizure activity originating in the amygdala are not limited to the amygdala itself, but may also affect other temporal lobe structures. The information gathered so far on damage to the amygdala in epilepsy or after status epilepticus suggests that local alterations in inhibitory circuitries may contribute to a lowered seizure threshold and greater excitability within the amygdala. Furthermore, damage to select nuclei in the amygdala may predict impairment of performance in behavioral tasks that depend on the integrity of the amygdaloid circuits.     

Strategic processing and memory for temporal order in patients with frontal lobe lesions.

This study evaluated whether deficits in memory for temporal order in patients with frontal lobe lesions result from impaired automatic encoding of temporal information or are secondary to deficits in effortful processes, such as the use of organizational strategies and control of interference. Patients with lesions in the dorsolateral prefrontal cortex and control participants were tested on temporal order reconstruction of semantically related and unrelated word lists learned under intentional or incidental conditions. Memory for temporal order in patients with frontal lobe lesions was sensitive to semantic relatedness but not to intention to learn. Tests of item free recall and recognition using similar encoding manipulations indicated that order performance in these patients was dissociable from item memory. Results indicate that automatic processing of temporal information is intact in patients with frontal lobe lesions but that strategic processing of this information is impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A unified account of cognitive impairments following frontal lobe damage: The role of working memory in complex, organized behavior.

A computer model is presented that performs 4 tasks sometimes impaired by frontal damage: motor sequencing, the Stroop task, the Wisconsin Card Sorting Test, and a context memory task. In each task, patterns of performance typical of frontal-damaged patients are shown to result from the same type of damage to the model, specifically, weakening of associations among elements in working memory. The simulation shows how a single underlying type of damage could result in impairments on a variety of seemingly distinct tasks. Furthermore, the hypothesized damage affects the processing components that carry out the task rather than a distinct central executive. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Spared discrimination and impaired reversal eyeblink conditioning in patients with temporal lobe amnesia.

The effect of medial temporal lobe damage on a 2-tone delay discrimination and reversal paradigm was examined in human classical eyeblink conditioning. Eight medial temporal lobe amnesic patients and their demographically matched controls were compared. Amnesic patients were able to distinguish between 2 tones during the initial discrimination phase of the experiment almost as well as control participants. Amnesic patients were not able to reverse the previously acquired 2-tone discrimination. In contrast, the control participants showed improved discrimination performance after the reversal of the tones. These findings support the hypothesis that the hippocampus and associated temporal lobe regions play a role in eyeblink conditioning that becomes essential in more complex versions of the task, such as the reversal of an acquired 2-tone discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subjective memory evaluations in patients with focal frontal, diencephalic, and temporal lobe lesion

This paper examines subjective memory evaluations and their correlates in patients with focal frontal, diencephalic, or temporal lobe lesions. Although all patient groups showed significantly lower subjective memory evaluations than healthy subjects, the temporal lobe group rated themselves significantly lower than the frontal lobe or diencephalic groups despite comparable severity of amnesia, implying more severely impaired 'insight' in the latter two groups. There was a 'temporal gradient' such that patients rated their memory for 'old' (premorbid) items better than their memory for 'new' (recent) or prospective items. As in previous studies, subjective memory evaluations were not correlated with measures of 'objective' anterograde memory performance, but the present study suggests that subjective evaluations are not randomly determined. It seemed to be the site of lesion (frontal and/or diencephalic), rather than underlying aetiology, which produced a particularly severe loss of 'insight'. Whether the earliest remote or autobiographical memories were preserved or not appeared to be an important correlate of current subjective memory evaluations, and patients who had been memory-disordered for longer were more likely to evaluate their memory as poor than those with a more recent onset.     

MMPI in differentiation of temporal lobe and nontemporal lobe epilepsy: Investigation of three levels of test performance.

Using carefully matched samples, a variety of MMPI techniques were explored in an attempt to document the clinically accepted personality differences between temporal lobe (n?=?37) and nontemporal lobe (n?=?28) epileptics. Analysis of the traditional clinical scales, as well as additional procedures employed in an attempt to improve test sensitivity (content scales, code type, category frequencies, and item analyses), did not support the position that temporal lobe epileptics are more likely to manifest personality disturbance than are other epileptics. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal and spatial context memory in patients with focal frontal, temporal lobe, and diencephalic lesions

Patients with focal frontal, temporal lobe, or diencephalic lesions were investigated on measures of temporal (recency) and spatial (position) context memory, after manipulating exposure times to match recognition memory for targets (pictorial stimuli) as closely as possible. Patients with diencephalic lesions from an alcoholic Korsakoff syndrome showed significant impairment on the temporal context (recency) task, as did patients with frontal lesions penetrating the dorsolateral frontal cortex, according to MRI (and PET) evidence. Patients with temporal lobe lesions showed only a moderate (non-significant) impairment on this task, and patients with medial frontal lesions, or large frontal lesions not penetrating the dorsolateral cortical margins, performed as well as healthy controls at this task. On the spatial context memory task, patients with lesions in the temporal lobes showed significant impairment, and patients with right temporal lesions performed significantly worse than patients with left temporal lesions. Patients with diencephalic lesions showed only a modest (non-significant) impairment on this task, and the frontal lobe group performed normally. When a group of patients with temporal lobe lesions resulting from herpes encephalitis were examined separately, an identical pattern of results was obtained, the herpes group being significantly impaired on spatial memory and showing a trend towards impairment for temporal context memory. There were strong correlations between anterograde memory quotients and context memory performance (despite the use of an exposure time titration procedure) and a weak association in the frontal group with one frontal/executive task [corrected] (card-sorting perservations). It is predicted that correlations between temporal context memory and frontal/executive tasks will be greater in samples of patients all of whom have frontal lesions invading the dorsolateral cortical margin.     

Comparative recovery following simultaneous- and successive-stage frontal brain damage in mice.

Conducted 5 experiments with female CF1 mice sustaining sham-operations, simultaneous, or successive bilateral frontal pole transections. Recovery of a passive-avoidance deficit occurred following both simultaneous and successive transsections. Recovery was a function of time either following the simultaneous procedure or between the 2 stages of the successive procedure. Recovered simultaneous Ss were hyposensitive to impairment of passive-avoidance learning by d-amphetamine, whereas recovered successive Ss were not. Alpha-methyltyrosine facilitated recovery following either simultaneous or successive brain damage. Results are consistent with a denervation supersensitivity model of recovery of function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

Dissociation of object recognition and spatial localization abilities following temporal lobe lesions in humans.

Discrete extrastriate cortical visual systems in nonhuman primates consisting of an occipitotemporal object recognition system and an occipitoparietal spatial localization system have been proposed. Patients undergoing left (n?=?81) or right (n?=?77) anterior temporal lobectomy were administered tests of object recognition (facial recognition) and spatial localization (line orientation) preoperatively and 6 mo postoperatively to determine the effects on the what and where visual systems. Postoperatively there was dissociation in performance with significant loss in facial recognition ability and concomitant improvement in line orientation performance. The pattern of performance was similar for both groups. The findings suggest that anterior temporal lobectomy had a specific effect on the occipitotemporal object recognition system while leaving the occipitoparietal spatial localization system unaffected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anterior temporal abnormality in temporal lobe epilepsy: a quantitative MRI and histopathologic study

OBJECTIVE: To examine the nature and frequency of anterior temporal lobe (AT) abnormalities that occur in intractable temporal lobe epilepsy (TLE). METHODS: We reviewed the MR scans and clinical histories of 50 consecutive patients with intractable TLE. Histopathology was available in 42 surgically treated cases. RESULTS: MRI demonstrated loss of the gray-white matter differentiation and decreased T1- and increased T2-weighted signal in the ipsilateral AT in 58% of the 50 patients. This appearance was observed in 64% of the 36 patients with hippocampal sclerosis (HS) but was also seen in patients without HS. These changes were associated with temporal lobe atrophy, a higher hippocampal T2 relaxation time, and a history of febrile convulsions. Pathologic examination showed that the MRI appearances were not caused by dysplasia, degenerative abnormalities, or inflammatory change. Histologic quantitation showed increased glial cell nuclei counts in the intractable TLE cases compared with controls. There was no difference in glial cell numbers between cases with AT abnormality and those without this appearance. Presence or absence of changes was not predictive of preoperative neuropsychology, postoperative change in neuropsychology, or seizure outcome after surgery. CONCLUSIONS: These frequently seen ipsilateral changes are not caused by gliosis and may reflect a nonspecific increase in water content in the temporal lobe. This may be due to myelin abnormalities or some other as yet unidentified pathologic factor.     

The differentiation of semantic dementia and frontal lobe dementia (temporal and frontal variants of frontotemporal dementia) from early Alzheimer's disease: A comparative neuropsychological study.

The authors compared age-matched groups of patients with the frontal and temporal lobe variants of frontotemporal dementia (FTD; dementia of frontal type [DFT] and semantic dementia), early Alzheimer's disease (AD), and normal controls (n?=?9 per group) on a comprehensive neuropsychological battery. A distinct profile emerged for each group: Those with AD showed a severe deficit in episodic memory with more subtle, but significant, impairments in semantic memory and visuospatial skills; patients with semantic dementia showed the previously documented picture of isolated, but profound, semantic memory breakdown with anomia and surface dyslexia but were indistinguishable from the AD group on a test of story recall; and the DFT group were the least impaired and showed mild deficits in episodic memory and verbal fluency but normal semantic memory. The frontal and temporal presentations of FTD are clearly separable from each other and from early AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateralization of the startle reflex circuit in humans: An examination with monaural probes following unilateral temporal lobe resection.

Startle reflex (SR) modulation elicited by monaural probes during affective picture viewing was investigated in patients following left temporal lobectomy (LTL; n = 8) and right temporal lobectomy (RTL; n = 10) and in controls (n = 18). All patients had undergone anteromedial temporal lobe (ATL) resection. LTL participants exhibited attenuated overall SR magnitude. Affective SR modulation in controls was significant for left ear probes, at both eyes, but not for right ear probes. RTL but not LTL participants displayed significant startle attenuation during pleasant picture viewing. Results suggest that monaural startle probes primarily activate structures in the ipsilateral ATL and that the ATLs are interconnected, with the left ATL more critical in perceiving arousing properties of affective stimuli, necessary for affective SR modulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact perceptual and conceptual priming in temporal lobe epilepsy: Neuroanatomical and methodological implications.

Explicit memory appears to be supported by medical temporal lobe structures, whereas separate neocortical regions may mediate perceptual and conceptual implicit memory. Children and adults with temporal lobe epilepsy (TLE) and matched controls were administered experimental verbal memory tests. Performance on implicit tests--word identification and word generation--was contrasted with explicit recognition and recall. Encoding conditions emphasized either conceptual or perceptual aspects of study words and were crossed with presentation modality. The priming performance of participants with TLE did not differ from controls, but participants with TLE did show deficits on recognition and recall measures. Thus, intact left temporal cortex does not appear to be necessary for normal implicit memory performance, even when conceptual processing is emphasized at study or test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Helplessness and escape performance: Glutamate-adenosine interactions in the frontal cortex.

Adenosine has been implicated as a proximate mediator of escape deficits in the learned helplessness paradigm, suggesting that neuronal overactivation--a typical precursor to adenosine release--precedes the inescapable shock-induced impairment (T. R. Minor, W. C. Chang, & J. L. Winslow, 1994). In the present experiments, glutamate (100 μg) injection into the rat frontal cortex produced a deficit in escape performance. Pretest treatment with the adenosine receptor antagonist caffeine (7 mg/kg ip) reversed the effect of glutamate when infused 1 hr, but not 72 hr, after glutamate injection. Finally, microinjection of 2-amino-5-phosphonovaleric acid (5 ng) into the frontal cortex prior to inescapable shock prevented the escape deficit. These findings are consistent with the involvement of N-methyl-D-aspartate receptor activation in the frontal cortex in the helplessness effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Talking about time: Effects of temporal planning and time awareness norms on group coordination and performance.

Planning is often central to effective coordination and task performance in work groups. Although planning pertains to efforts aimed at establishing objectives, generating subtasks, and creating role or task assignments, it also encompasses discussions about time and temporal issues. This article highlights the importance of temporal planning in groups, especially as it relates to effective coordination and task performance. Specifically, the results of a survey study of 48 self-managing project groups revealed that higher levels of initial temporal planning contributed to the formation of group norms that emphasize awareness of and attention to time. These time awareness norms were found to mediate the effect of temporal planning on coordination and task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Material-specific memory in temporal lobe epilepsy: Effects of seizure laterality and language dominance.

This study investigated the effects of seizure laterality and language dominance on material-specific memory in temporal lobe epilepsy (TLE). Left TLE (LTLE) patients with left-hemisphere language dominance (LHLD) showed significantly higher nonverbal than verbal memory capacity, whereas right TLE patients with LHLD showed significantly better verbal than nonverbal memory capacity. LTLE patients with non-left-hemisphere language dominance (NLHLD) showed significantly better verbal memory capacity compared with LTLE patients with LHLD. Thus, selective verbal or nonverbal memory deficits that are dependent on side of seizure onset were apparent in patients with LHLD but not in patients with NLHLD. Relative sparing of verbal memory capacity in LTLE patients with NLHLD may reflect interhemispheric reorganization of verbal memory function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The anterior and posterior selective temporal lobe amobarbital tests: angiographic, clinical, electroencephalographic, PET, SPECT findings, and memory performance

The techniques, results, and problems of three types of selective temporal lobe (TL) amobarbital procedures (balloon technique with temporary occlusion of the internal carotid artery distal to the origin of the anterior choroidal artery (acha) [n = 19]; selective anterior catheterization of the acha [n = 20]; and selective catheterization of the peduncular P2-segment of the posterior cerebral artery [n = 5]) are described in a group of 40 patients with medically refractory complex partial seizures of mesial TL origin. Selective amobarbital tests were carried out before surgery to predict the memory deficit after an intended selective amygdalohippocampectomy. The effects of selective anaesthetization of TL were correlated with clinical data, pattern and duration of amobarbital induced EEG changes, and performance on verbal and nonverbal memory tasks measured during the test. In 4 patients the effect of selective amobarbital injection on regional and global metabolism was studied with 18F-FDG-PET, with the PET tracer being injected intravenously immediately after amobarbital. More recently in 2 patients the vascular territory perfused by amobarbital in the acha test was studied with SPECT using 99m Tc ECD injected immediately prior to the amobarbital into the acha. Whereas the PET studies showed a rather widespread and bilateral amobarbital-induced decrease of metabolism, the SPECT studies confirmed the selective distribution of the tracer in the vascular territory of the acha, i.e., in amygdala and hippocampus. The comparison of selective TL amobarbital test performance with postoperative neuropsychological performance showed that the predictive value of this test is rather good for the postoperative verbal memory but underestimates postoperative nonverbal ("figural") memory performance.