Inhibition of ongoing responses following frontal, nonfrontal, and basal ganglia lesions.

The authors investigated the role of the frontal lobes and the basal ganglia in the inhibition of ongoing responses. Seventeen patients with frontal lesions (FG), 20 patients with lesions outside the frontal cortex (NFG), 8 patients with lesions to the basal ganglia (BG), and 20 orthopedic controls (OG) performed the stop-signal task that allows the estimation of the time it takes to inhibit an ongoing reaction (stop signal reaction time [SSRT]). The FG and the BG showed significantly longer SSRTs than the OG. Within the FG, patients with right and bilateral lesions showed significantly longer SSRTs than patients with left lesions. Results provide evidence for a role of the frontal lobes and the basal ganglia in the inhibition of ongoing responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental-rotation deficits following damage to the right basal ganglia.

The authors report the case of a woman with a right basal ganglia lesion and severe mental-rotation impairments. She had no difficulty recognizing rotated objects and had intact left-right orientation in egocentric space but was unable to map the left and right sides of external objects to her egocentric reference frame. This study indicates that the right basal ganglia may be critical components in a cortico-subcortical network involved in mental rotation. We speculate that the role of these structures is to select and maintain an appropriate motor program for performing smooth and accurate rotation. The results also have important implications for theories of object recognition by demonstrating that recognition of rotated objects can be achieved without mental rotation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk factors for silent cerebral infarcts in subcortical white matter and basal ganglia

BACKGROUND AND PURPOSE: The purpose of this study was to clarify whether the relevant risk factors for silent cerebral infarcts (SCIs) in subcortical white matter (WM) are different from those in the basal ganglia (BG). METHODS: Subjects of this study were 219 adults without a history of stroke or transient ischemic attack and without any abnormality on a neurological examination who consecutively visited the neurology service in our hospital between January 1994 and November 1997 requesting medical evaluation for possible cerebrovascular diseases. Subjects included 141 men and 78 women ranging in age from 33 to 83 years (mean+/-SD, 63.2+/-9.5 years). We performed brain MRIs and cervical/cranial MR angiographies on all subjects. In this study, SCI was defined as a focal lesion >5 mm in diameter that was prolonged on both T2-weighted and proton density images. RESULTS: SCIs in the WM and/or BG were detected in 88 (40.2%) of the 219 subjects. No SCI >15 mm was observed in this series. Fifty of the subjects had SCIs only in the WM, 32 subjects had SCIs in both the WM and BG, and 6 subjects had SCIs only in the BG. Thus, 82 (93.2%) of 88 subjects with SCIs had lesions in the WM. Most subjects with SCIs in the BG also had SCIs in the WM. Multiple logistic regression analyses revealed that age, female sex, and hypertension were significant and independent predictors of SCIs in the WM, and that age, a history of ischemic heart disease, and carotid artery stenosis were significant and independent predictors of SCIs in the BG. CONCLUSIONS: The present study indicated that the relevant risk factors for SCIs in the WM and those for SCI in the BG were different. Our results suggest that SCIs are prone to first appear in the WM in association with aging and hypertension, and the additional appearance of SCIs in the BG predicts a progression of generalized atherosclerosis that is manifested in the carotid and coronary arteries.     

Neurological signs and frontal white matter lesions in vascular parkinsonism. A clinicopathologic study

BACKGROUND AND PURPOSE: The clinical characteristics and the pathological lesions of so-called vascular parkinsonism (VP) are still debatable. The purpose of this study was to define the core signs and symptoms and assess the cerebrovascular lesions in pathologically confirmed VP. METHODS: In the present study, VP was defined as the presence of parkinsonism and pathological evidence of cerebrovascular lesions but no depigmentation or Lewy bodies at the substantia nigra. We compared the clinical signs and symptoms of 24 VP patients with those of 30 age-matched patients with pathologically confirmed Parkinson's disease. We compared the brain pathology in VP patients with that in 22 age-matched patients with Binswanger's disease (BD) who had no parkinsonism according to clinical records. RESULTS: VP was characterized clinically by a short-stepped or frozen gait, lead-pipe rigidity, absence of resting tremor, and negative response to levodopa. Half or more of VP patients demonstrated pyramidal tract signs and pseudobulbar palsies. There was no significant difference in the extent of vascular lesions at the basal ganglia between patients with VP and with BD without parkinsonism. The extent of frontal white matter pallor tended to be less broad in VP than in BD without parkinsonism. In VP patients, the number of oligodendrocytes in the frontal white matter was significantly less than that in age-matched normal control subjects and significantly more than in those with BD. CONCLUSIONS: The core signs and symptoms of autopsy-proved VP differ from those of typical Parkinson's disease, and most VP patients had diffuse cerebral white matter lesions as well as basal ganglia lesions. VP might be related to frontal white matter lesions.     

Expressive aprosodia following stroke to the right basal ganglia: A case report.

Presented here is a case report of a 16-yr-old adolescent who, after experiencing an embolic stroke to subcortical structures of the right hemisphere, evidenced motor aprosodia. The patient was administered a test of receptive emotional prosody. In addition, the patient was asked to state a series of stimulus sentences to determine if she was able to spontaneously convey emotions (happy, sad, mad) appropriately and was asked to repeat a series of stimulus sentences to determine if she could convey the same emotions as the speaker. She demonstrated aprosodic-agestural speech, aprosodic repetition, and good prosodic comprehension. This case report supports the notion of right-hemisphere organization of the emotional aspects of language and the existence of subcortical aprosodias analogous to subcortical aphasias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shearing injuries of parasagittal white matter, corpus callosum and basal ganglia: possible radiological evidences of hemiplegia in diffuse axonal injury

The relationship between spastic hemiplegia in diffuse axonal injury (DAI) and neuroradiological findings was studied in 100 cases. These cases were prospectively collected from the files of Automobile Insurance Rating Organization in Japan between 1993 from to 1996. Requirements for entry to this study were as follows: presence of initial unconsciousness after head injury without any lucid interval. Existence of CT scan or MRI film obtained within 12 hours of injury showing no significant mass effects, as well as follow-up CT scan or MRI film obtained more than 3 months after the injury. Psychosocial outcome was described both by the medical professional and the caregiver. The hemiplegia was rated severe, mild, or none. The outcome and diffuse ventriculomegaly were classified as reported by the authors previously. Spastic hemiplegia or quadriplegia was documented in the chronic stage in 63 cases, including 53 severe cases with difficulty in walking and 10 mild cases with only pyramidal signs detected. Chi-square analysis showed significant correlation between hemiplegia and the DAI outcome level or ventriculomegaly rating. Focal brain contusion was noticed in 33 cases, but did not correlate with the hemiplegia at all. Radiological findings included 25 cases of parasagittal white matter injury (gliding contusion), 20 cases of callosal injury, 19 cases of basal ganglionic region injury, 5 cases of brain-stem injury, and 3 cases of cerebellar injury. Chi-square analyses of hemiplegia and contralateral presence of these injuries were significant in the former three types of injury. Presence of at least one of these 3 lesions was defined as GCB injury. There were altogether 46 GCB injury cases which were significantly correlated with contralateral hemiplegia by chi-square analysis and by Spearman rank analysis. Partial correlation analysis with hemiplegia as the target variable indicated highly significant correlation only with GCB injury and outcome level. In conclusion, spastic hemiplegia in DAI is a manifestation of primary shear injury. Neuroradiological findings of GCB injury were statistically able to be significantly correlated with the presence of hemiplegia, and suggested pyramidal tract injury either at the corona radiata or the internal capsule level.     

Schizophrenia, psychosis, and the basal ganglia

Schizophrenia is one of the most common and perhaps the most disabling of mental disorders, for which effective forms of treatment have not yet been established definitively. The findings reviewed in this article strongly suggest that basal ganglia abnormalities are involved in the pathophysiology of psychotic syndromes in general, and schizophrenia in particular.     

Automatic identification of gray matter structures from MRI to improve the segmentation of white matter lesions

The segmentation of MRI scans of patients with white matter lesions (WML) is difficult because the MRI characteristics of WML are similar to those of gray matter. Intensity-based statistical classification techniques misclassify some WML as gray matter and some gray matter as WML. We developed a fast elastic matching algorithm that warps a reference data set containing information about the location of the gray matter into the approximate shape of the patient's brain. The region of white matter was segmented after segmenting the cortex and deep gray matter structures. The cortex was identified by using a three-dimensional, region-growing algorithm that was constrained by anatomical, intensity gradient, and tissue class parameters. White matter and WML were then segmented without interference from gray matter by using a two-class minimum-distance classifier. Analysis of double-echo spin-echo MRI scans of 16 patients with clinically determined multiple sclerosis (MS) was carried out. The segmentation of the cortex and deep gray matter structures provided anatomical context. This was found to improve the segmentation of MS lesions by allowing correct classification of the white matter region despite the overlapping tissue class distributions of gray matter and MS lesion.     

Relationship between vascular factors and white matter low attenuation of the brain

There are few reports on contralateral or metachronous adrenal gland metastases in renal cell carcinoma (RCC) in the literature. Since sonography has been more frequently used in follow-up examinations these metastases have been found more often. We report on five patients with solitary metastases from RCC to the ipsi- or contralateral adrenal gland.     

A serial study of new MS lesions and the white matter from which they arise

OBJECTIVE: To compare MS normal-appearing white matter (NAWM) where new gadolinium-enhancing (Gd+) lesions do and do not arise. METHODS: A total of 22 relapsing-remitting MS patients and 11 healthy control subjects completed as many as 12 monthly brain MRI sessions. Quantitative measures of gadolinium enhancement (GDR), water proton density (PDN), water proton T2 relaxation time constants (T2), magnetization transfer ratio (MTR), and T1-weighted signal intensity (T1N) were followed serially in healthy control and MS NAWM. RESULTS: A total of 129 new Gd+ lesions were identified in 11 patients. PDN, T2, MTR, and T1N were diffusely abnormal in MS NAWM. NAWM regions in which new Gd+ lesions arose have increased GDR, PDN, and T2, and reduced MTR and T1N compared with contralateral homologous NAWM regions in which no new Gd+ lesions arose. Differences between these NAWM regions preceded lesion appearance for at least several months. After lesions became visible, GDR returned to baseline within 2 months, and PDN and MTR had larger residual abnormalities than T2 or T1N. CONCLUSIONS: Quantitative MRI measures are diffusely abnormal in MS NAWM. These measures are, on average, more abnormal in NAWM regions in which new Gd+ lesions arise. After the appearance of Gd+ lesions, measures of PDN and MTR may provide more appealing markers of relatively irreversible tissue damage than measures of T2 and T1N.     

Radio-frequency lesions of the thalamus produce delayed-nonmatching-to-sample impairments comparable to pyrithiamine-induced encephalopathy in rats.

Rats were trained and matched on a delayed-nonmatching-to-sample (DNMTS) task and randomly assigned to treatment. In Exp 1, radio-frequency (RF) lesions were aimed at lateral portions of the internal medullary lamina (L-IML), midline thalamus (MT), mammillary bodies (MB), and the combination of MT and MB. In Exp 2, RF lesions were aimed at the fornix. After recovery, DNMTS was retrained at retention intervals of 3.0–28.0 sec, the critical retention level for 75% DNMTS accuracy was determined by a staircase procedure, and spontaneous exploration was observed in an open field. L-IML lesions produced significant deficits on DNMTS and exploratory behavior that were comparable to deficits on the same tasks in rats recovered from pyrithiamine-induced thiamine deficiency. Fornix lesions produced significant DNMTS deficits that were substantially smaller than for the L-IML group. The MT, MB, and MT?+?MB treatments had no significant effect on DNMTS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gustatory thalamus lesions in the rat: II. Aversive and appetitive taste conditioning.

The learning capacities of rats with electrolytic lesions of the gustatory thalamus (GT) were investigated in 3 experiments. In Experiment 1, the presence of a taste cue failed to overshadow odor aversion learning in the lesioned rats, yet these same animals acquired normal taste and odor aversions. Thalamic lesions had no discernible effect on the acquisition of a conditioned flavor preference in Experiment 2. Finally, GT lesions completely reversed the anticipatory contrast effect shown by control subjects in Experiment 3. These results suggest that damage to the GT spares taste detection and recognition and simple associative learning but interferes with learning that involves more complex gustatory information processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human T-cell lymphotropic virus type 1 myositis, peripheral neuropathy, and cerebral white matter lesions in the absence of spastic paraparesis

BACKGROUND: The human T-cell lymphotropic virus type 1 (HTLV-1) is associated with a chronic, progressive myelopathy termed tropical spastic paraparesis or HTLV-1-associate myelopathy. An increasing number of reports suggest that the spectrum of neurologic diseases associated with HTLV-1 is quite diverse. DESIGN: Case study. SETTING: A university teaching hospital (Ottawa General Hospital, Ottawa, Ontario). RESULTS: Serum creatine kinase levels were elevated (1091 U/L). Antibodies for HTLV-1 were detected by Western blot analysis and confirmed by polymerase chain reaction. Human immunodeficiency virus antibodies were not detected. Findings of nerve conduction studies revealed an axonal neuropathy, while results of needle electromyography were consistent with mixed neuropathic and myopathic changes. Findings of a muscle biopsy supported the presence of polymyositis. Magnetic resonance imaging scans of the brain showed chronic, extensive cerebral white matter involvement of more than 7 years' duration. Treatment with oral steroids resulted in an approximate 40% decrease in serum creatine kinase levels within 1 month and a marked improvement in strength. CONCLUSIONS: A broad spectrum of neurologic disorders is associated with HTLV-1, which may or may not include spastic paraparesis. Patients with myopathies and/or neuropathies of unknown origin who are from areas endemic for HTLV-1 should be screened for this retrovirus, even in the absence of spastic paraparesis.     

Effects of global atrophy, white matter lesions, and cerebral blood flow on age-related changes in speed, memory, intelligence, vocabulary, and frontal function.

Brain images were obtained from 133 healthy people of ages 61-85 years who completed 20 tests of information processing speed, intelligence, frontal and executive function, memory, and vocabulary. Structural equation models examined relationships between cognitive test scores, ages and measurements of global age-associated atrophy, white matter lesions, and cerebral blood flow. These neurophysiological measures jointly account for all age-related variance in information processing speed. Speed entirely mediated relationships between neurophysiological measures and memory and partly mediated relationships between neurophysiological measures and intelligence and frontal function. Neurophysiological measures, but not calendar age, accounted for vocabulary scores. Cognitive slowing was responsible for some, but not all, age-related declines in mental function. Age-related declines in intelligence, frontal function, and speed were due to changes in different functional systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioural context and a distributed system: Metabolic mapping studies of the basal ganglia.

Used metabolic mapping to determine if a distributed, anisotropic pattern of striatal processing would be affected by behavioral context. Male rats were trained, in a particular environment, to make licking movements in a situation where accurate performance depended upon sensory feedback from the perioral/vibrissa area. Probe stimulation of the perioral/vibrissa area was presented noncontingently to these Ss when they were at rest in the training environment. The resulting pattern of striatal activation was compared with that of untrained Ss receiving physically equivalent probe stimuli. The study found that behavioral context affected the way in which the striatum processes somatosensory information, within a relatively large somatosensory territory of the striatum. An overall map of the striatum that localizes changes related to this remarkable phenomenon of contextual responses contributes to the understanding of anatomical substrates of neural systems that integrate information, and may lead to new striatal regions to study synaptic mechanisms of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory impairment in monkeys following lesions limited to the hippocampus.

Investigated the degree of memory impairment produced by a lesion limited to the hippocampus in 13 cynomolgus monkeys (Macaca fascicularis) with circumscribed hippocampal lesions who were tested on the delayed-nonmatching-to-sample task, a test of recognition memory that is sensitive to amnesia in humans. Ss were given no preoperative training and were given no postoperative experience prior to training on the task. A marked deficit was observed. The results, taken together with those from previous studies, also provide information about the role of factors that could potentially influence the level of memory impairment following hippocampal lesions. The level of impairment does not appear to be due to any of the following factors: time of testing after surgery, prior postoperative testing, surgical techniques, species differences, or behavioral training methods. However, preoperative training experience does appear to reduce the severity of the impairment, and this factor may account for the observation that the memory impairment associated with hippocampal lesions is sometimes mild. A recent case of human amnesia is discussed in which a bilateral lesion limited to a portion of the hippocampus produced a well-documented memory deficit. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

GABAergic and cholinergic basal forebrain and preoptic-anterior hypothalamic projections to the mediodorsal nucleus of the thalamus in the cat

The present study examined projections of GABAergic and cholinergic neurons from the basal forebrain and preoptic-anterior hypothalamus to the "intermediate" part of the mediodorsal nucleus of the thalamus. Retrograde transport from this region of the mediodorsal nucleus was investigated using horseradish peroxidase-conjugated wheatgerm agglutinin in combination with peroxidase-antiperoxidase immunohistochemical staining for glutamic acid decarboxylase and choline acetyltransferase. A relatively large number of retrogradely-labelled glutamic acid decarboxylase-positive neurons are located in the basal forebrain, amounting to more than 7% of the total population of glutamic acid decarboxylase-positive cells in this region. Moreover, retrogradely-labelled choline acetyltransferase-positive cells are interspersed among glutamic acid decarboxylase-positive neurons, accounting for about 6% of the total choline acetyltransferase-positive cell population in the basal forebrain. The glutamic acid decarboxylase-positive and choline acetyltransferase-positive retrogradely-labelled neurons are distributed throughout several regions of the basal forebrain, including the medial septum, the diagonal band of Broca, the magnocellular preoptic nucleus, the substantia innominata pars anterior, the substantia innominata pars posterior, and the globus pallidus where only a few retrogradely-labelled neurons were seen. The choline acetyltransferase-positive mediodorsal-projecting neurons are morphologically different from the choline acetyltransferase-positive neurons in the basal forebrain, suggesting that those projecting to the mediodorsal nucleus are a small proportion of the cholinergic neuronal population in the basal forebrain. In the preoptic-anterior hypothalamus, many retrogradely-labelled glutamic acid decarboxylase-positive cells were found, amounting to more than 7% of the total population of glutamic acid decarboxylase-positive cells in this region. These retrogradely-labelled glutamic acid decarboxylase-positive neurons are distributed throughout the preoptic-anterior hypothalamus in a continuous line with those in the basal forebrain, including the lateral preoptic area, the medial preoptic area, the bed nucleus of the stria terminalis, and the anterior and dorsal hypothalamic areas. The highest percentage of mediodorsal-projecting GABAergic neurons is in the anterior lateral hypothalamus where more than 25% of the total population of glutamic acid decarboxylase-positive cells project to the mediodorsal nucleus of the thalamus. Overall, of the large population of retrogradely-labelled neurons in the basal forebrain and preoptic-anterior hypothalamus, a significant proportion are glutamic acid decarboxylase-positive neurons (> 60% in the basal forebrain and > 30% in the preoptic-anterior hypothalamus), while the choline acetyltransferase-positive neurons amount to a smaller percentage of the neurons projecting to the mediodorsal nucleus (< 13% in the basal forebrain and < 2% in the preoptic-anterior hypothalamus). These results provide anatomical evidence of direct GABAergic projections from the basal forebrain and preoptic-anterior hypothalamic regions to the "intermediate" part of the mediodorsal nucleus in the cat. This GABAergic projection field could be the direct pathway by which the basal forebrain directly modulates thalamic excitability and may also be involved in mechanisms modulating electroencephalographic synchronization and sleep through the "intermediate" mediodorsal nucleus.     

Delayed-nonmatching-to-sample performance is impaired by extensive, but not by limited, lesions of the thalamus in the rat.

Two experiments were conducted to determine whether lesions affecting limited areas of the thalamus can impair the performance of rats on a spatial delayed-nonmatching-to-sample (DNMTS) task trained before surgery. In Exp 1, DNMTS was not affected by lesions produced by injecting 5 μl of 1 mM N-methyl-D-aspartate (NMDA) into either the midline thalamus (n?=?16) or bilaterally 1.0 mm from the midline (n?=?16). In Exp 2, radio-frequency lesions were made 1.0 mm lateral from the midline at 3 anterior–posterior locations that destroyed the full rostral–caudal extent of the lateral internal medullary lamina (L-IML; n?=?8), or at single anterior–posterior locations that destroyed either the anterior (n?=?8) or posterior (n?=?8) portions of the L-IML site. Although complete L-IML lesions disrupted DNMTS performance to an extent comparable to that of another study (R. G. Mair and D. M. Lacourse; see record 1992-42024-001), lesions that were restricted to either the anterior or posterior portion of the L-IML site had no significant effect on this task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electro-acupuncture stimulation acts on the basal ganglia output pathway to ameliorate motor impairment in Parkinsonian model rats.

The role of electro-acupuncture (EA) stimulation on motor symptoms in Parkinson’s disease (PD) has not been well studied. In a rat hemiparkinsonian model induced by unilateral transection of the medial forebrain bundle (MFB), EA stimulation improved motor impairment in a frequency-dependent manner. Whereas EA stimulation at a low frequency (2 Hz) had no effect, EA stimulation at a high frequency (100 Hz) significantly improved motor coordination. However, neither low nor high EA stimulation could significantly enhance dopamine levels in the striatum. EA stimulation at 100 Hz normalized the MFB lesion-induced increase in midbrain GABA content, but it had no effect on GABA content in the globus pallidus. These results suggest that high-frequency EA stimulation improves motor impairment in MFB-lesioned rats by increasing GABAergic inhibition in the output structure of the basal ganglia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intellectual impairment and brain MRI findings in myotonic dystrophy: with a special reference to hippocampal atrophy and white matter lesions

We performed a correlative study between intellectual impairment, CTG repeat expansion and magnetic resonance imaging (MRI) abnormalities, including hippocampal atrophy, white matter lesions and ventricular dilatation in 15 patients with myotonic dystrophy (MD). They included 4 males and 11 females aged from 20 to 66 years, averaging 43 years of age and 15 years of duration of illness. Nine patients had intellectual impairment (WAIS-R<80). Negative correlations were found between full scale IQ (FSIQ), duration of illness (p<0.05) and CTG repeat expansion (p<0.05). Compared with normal controls, the patients with MD showed a significant reduction in size of the hippocampal head (p<0.01), which was positively correlated to FSIQ, verbal IQ and performance IQ levels (p<0.05). Ten patients had white matter lesions. Severer white matter lesions tended to be recognized in patients with longer duration of illness and with decreased FSIQ level. These results suggest that hippocampal atrophy and white matter lesions are related to intellectual impairment in patients with MD.