Hemisphere Function Research Articles

Lateralized neuropsychological functioning in depressive patients before and after drug therapy

Several decades of research have led to different hypotheses about cognitive functioning in depression; one of the hypotheses states that there is altered functioning of the hemispheres during a depressive episode. Lateralization studies have found diminished neuropsychological functioning in depressive patients; especially right-hemisphere functions seem impaired. In our study we used conventional neuropsychological tests to study shifts in hemispheric functioning. Neuropsychological testing before and after therapy in 52 (for the most part therapy-resistant) depressives showed no substantial effects in lateralized functioning. None of the measures enabled prediction of response to treatment; however 17 different interaction variables were identified, five of which make an unique contribution.

Cerebellar induced aphasia: case report of cerebellar induced prefrontal aphasic language phenomena supported by SPECT findings

A 73-year-old right-handed man with ischemic infarction in the vascular territory of the right arteria cerebellaris superior is described. In the acute phase he presented with cerebellar and brainstem symptoms, followed within a few days by a paresis of the right arm and unexpected language disturbances of aphasic origin. The core features of the aphasic syndrome corresponded to a diagnosis of Luria's dynamic aphasia, complicated by expressive and receptive agrammatism. During one year follow-up the ataxia and paretic symptoms disappeared but the slightly ameliorated aphasic syndrome and the sensory disturbances in the left hemicorpus persisted. In the absence of any neuroradiological evidence for a structural lesion in the left frontal language areas, the hypothetical causative role of the right cerebellar lesion on the contralateral prefrontal aphasic symptomatology is advocated and supported by positive 99mTc-hexamethylpropyleneamine oxime single-photon emission-computed tomography findings, revealing a focal hypoperfusion in the clinically suspected areas. In our case, this phenomenon of so-called ‘crossed cerebello-cerebral diaschisis’, reflecting the distant functional impact of the right cerebellum on the contralateral prefrontal cortical areas, is for the first time associated with an aphasiologic substrate. The co-occurrence of a right cerebellar lesion and an aphasic syndrome forms the first clinical illustration of the pathophysiological hypothesis of a deactivation of prefrontal left hemisphere language functions due to the loss of excitatory impulses through cerebello-ponto-thalamocortical pathways.

Neuropsychological deficits among older depressed patients with predominantly psychological or vegetative symptoms

Depressed outpatients having primarily psychological or vegetative symptoms, as defined by the factor analytically developed Hamilton Depression Scale superfactors described by Rhoades and Overall (1983), were compared with similarly aged normal controls on a comprehensive neuropsychological battery. The vegetative group evidenced poorer performance than controls on several measures associated with right hemisphere functioning and on a task associated with executive functioning. In contrast, the psychological group did not significantly differ from controls on any measure, and had significantly better performance than the vegetative group on several tasks. These findings suggest that neuropsychological deficits associated with depression may be limited to those patients with primarily vegetative symptoms.

Neuropsychological consequences of traumatic brain injury in children and adolescents.

The study of the relationship between neuroscientific information and cognitive function and dysfunction is clearly a widely expanding field. In particular, there has been a growing body of research on traumatic brain injury (TBI) in children and adolescents. This article conveys recent findings concerning cognitive outcomes, with a particular focus on age differences with TBI, suggests a relationship between specific learning disorders and brain dysfunction, addresses differential hemisphere functioning with TBI, and alludes to recent developments in assessment of TBI.

Prospective associations between lateralised brain function and immune status in HIV infection: Analysis of EEG, cognition and mood over 30 months

Prospective relations between individual differences in both lateralised neuro-psychophysiological functions and mood ratings with immune status (CD4 and CD8 counts) were examined in asymptomatic HIV-positive men ( n = 27) over thirty months. They participated in a controlled study of zidovudine versus placebo (results published elsewhere). Measures included EEG spectra, neuropsychological tests and mood ratings. A model of reciprocal lateralised influences on the immune system was tested whereby patients with left superior to right hemispheric functions were predicted to show a less deleterious outcome than those with the opposite asymmetry pattern. Prospective relations with immune status were found in the EEG with lateralised theta, alpha and betaI activity; among cognitive measures with word fluency, semantic processing, and lateralised motor and recognition memory (word/face) processes; with mood ratings including depression, confusion and the total mood score. The nature of the effects supported the laterality predictions. These unique data, showing that neuro-psychophysiological factors in HIV + but otherwise healthy subjects predict immune competence and compromise present 2–3 years later, warrant replication in a larger cohort.

WOMEN: A MORE BALANCED BRAIN?

Abstract. On the basis of knowledge prior to 1988, Ashbrook pointed out that whereas most men are primarily dependent on the left cerebral hemisphere (“dominant hemisphere”) for verbally related functions, women show a greater hemispheric balance in this respect. For men, he argues, their possession of a “speaking” and a “non‐speaking hemisphere” results in a positive‐negative, bipolar way of thinking that may be characterized as dualistic and dialectically hierarchical. In contrast, the greater balance of hemispheric function in women appears to promote greater generalization and synthesis in their thinking.In this article I cite more recent neuroanatomical and brain imaging studies that provide further evidence of disparities in structure and function of the brains of men and women. As background for an attempt to explain these differences, I give a brief review of the triune evolution of the mammalian brain leading up to the human cerebrum. It is of major significance that the female has played a central role in mammalian evolution for more than 180 million years and that the evolutionary transition from reptilian therapsids to mammals is characterized by the develoment of (1) nursing conjoined with maternal care; (2) audiovocal communication or aiding mother‐offspring contact; and (3) play. In human beings, the infant‐carrying hypothesis suggests one means by which, over generations, certain parts of a woman's right hemisphere could undergo functional and eventual anatomical expansion. The mother‐infant communication of basic mammalian sounds with vowel and consonant components suggests a basis for the origination of speech.Finally, in an expansion of Ashbrook's original thesis, we arrive at the rovocative consideration that, unlike men, with their dialectical reasoning, women, with their more balanced brain, are provided with a trialectial ladder for climbing to achieve knowledge. In terms of quantum mechanics, the particle and wave would correspond to the substance and strength of the sides of the ladder, and the derived psychic information (which is neither matter nor energy) would compare to the rungs in between.

Delirium and right-hemisphere dysfunction in cognitively impaired older persons.

Cognitive impairment has been repeatedly shown to be a delirium risk factor. Much indirect evidence suggests that right-hemisphere dysfunction plays a particularly important role. This retrospective, case-controlled study, from a 148-patient memory loss clinic database, compared neuropsychological measures of hemispheric function in cognitively impaired elderly veterans with and without a history of delirium. Eleven study subjects had a history compatible with DSM-III-R criteria for delirium. Controls selected from the same database had no known history of delirium and were matched for Mini-Mental State Examination scores and Geriatric Depression Scale scores. Compared to the controls, subjects with a history of delirium had significantly lower scores on Object Assembly and Visual Reproduction (p < .05), tests that are predominantly right-hemisphere dependent. There were no significant differences in left-hemisphere measures. It is concluded that right-hemisphere dysfunction may prove to be an important risk factor for delirium.

Differences in Hemispheric Asymmetry Between Dyslexic and Normal Children on a Lateralised Lexical Decision Task

The present experiment was conducted in order to further investigate the relationship between deficits in left hemisphere processing and phonetic decoding in dyslexic children. We administered a lateralised lexical decision task that manipulated wordness, length, and word regularity of grapheme-phoneme conversion. Right-handed male dyslexic children and normal control children were presented with words and pronounceable nonwords. Although there were no overall differences in hemispheric asymmetry between the groups, they did differ in laterality effects in accuracy when responding to nonwords and to phonetically regular words, with the normal children showing the right visual field advantage/ sensitivity (left hemisphere dominance/sensitivity), while the dyslexics failed to show any visual field advantage or sensitivity for these stimuli. Further, group differences were observed in left but not right hemisphere functioning. The results suggest that deficits in left hemisphere processing are apparent only when the dyslexics are attempting to utilise the rules of phonics. Support for the use of this paradigm for use with dyslexic children is also discussed.

Cerebral laterality in affect and affective illness: a review.

It is generally claimed that affect processing is a right hemisphere function. It is also claimed that right hemisphere dysfunction is characteristic of depressive illness. These claims are not accepted without controversy, and it has been found that the relationship between affect processing and affective illness in terms of intra- and interhemispheric role is not straightforward. Two types of studies were reviewed in this context: behavioral and electrophysiological. Potential confounding effects are discussed.

Temporal Processing Asymmetries Between the Cerebral Hemispheres: Evidence and Implications

This paper reviews a large body of research which has investigated the capacities of the cerebral hemispheres to process temporal information. This research includes clinical, non-clinical, and electrophysiological experimentation. On the whole, the research supports the notion of a left hemisphere advantage for temporal resolution. The existence of such an asymmetry demonstrates that cerebral lateralisation is not limited to the higher-order functions such as language. The capacity for the resolution of fine temporal events appears to play an important role in other left hemisphere functions which require a rapid sequential processor. The functions that are facilitated by such a processor include verbal, textual, and fine movement skills. The co-development of these functions with an efficient temporal processor can be accounted for with reference to a number of evolutionary scenarios. Physiological evidence favours a temporal processing mechanism located within the left temporal cortex. The function of this mechanism may be described in terms of intermittency or travelling moment models of temporal processing. The travelling moment model provides the most plausible account of the asymmetry.

The Role of Temperament and Gender in Functional Hemispheric Asymmetry and the Perception of Emotion

Research investigating the relation between Functional Hemispheric Asymmetry (FHA) and the perception of affect in clinical as well as normal populations, is characterized by contradictory findings regarding the role of the different hemispheres, especially as regards the perception of various valencies of emotions. Although various methodological problems or error variances are often blamed for the contradictory findings and general lack of consensus, the literature is increasingly pointing to the existence of evidently reliable individual differences between people regarding their hemispheric functioning. The problem investigated in this study was to determine the possible role of some organismic variables in FHA. The objectives of this study were to determine whether there were significant differences in the direction of FHA-differences, as well as the relative performance, of groups divided according to gender and temperament characteristics, and whether the relevant organismic variables offered a possible means of explaining the contradictions in research results on FHA and the perception of emotion. The subject population ( N = 112) comprised four groups of right-handed students selected in terms of gender and temperament (introversion-extraversion). Differential hemispheric performance in terms of response accuracy and latency was determined by means of the Divided Visual Field Technique (DVFT). The results indicated that gender but not the temperament dimension of introversion-extraversion, plays a significant role in the degree and direction of FHA in the perception of emotion. It appears that the organismic variable gender could possibly offer a partial explanation for the contradictory results in the literature specifically with regard to FHA in the perception of emotion generally, and in respect of different valencies of emotion. However, the lack of significance in some of the results, especially with regard to men, impedes a firm empirical conclusion and explanation of the results.

Schizotypy and lateralised negative priming in schizophrenics' and neurotics' relatives

Schizophrenics' relatives were compared with neurotics' relatives on a range of schizotypy scales and a hemisphere information processing (negative priming) task. On most of the schizotypy scales schizophrenics' relatives had lower scores than neurotics' relatives, and also as compared with the normative data for the questionnaires used. This might have been due to volunteer bias or to defensive responding, though if the latter was the case it was not reflected in the level of ‘Lie’ scale scoring found among schizophrenics' relatives. The experimental task showed no significant differences when subjects were compared according to relatives' status. However, two significant differences did emerge when the total sample was divided on the basis of high/low schizotypy scores: high schizotypes showed (a) a lack of visual field asymmetry in lateralised negative priming, and (b) unusually fast overall reaction times to stimuli in the left visual field. Both observations are consistent with some recent speculations about hemisphere functioning as it relates to information processing and activation bias in schizophrenia and schizotypy.

Global/local task indices of hemispheric and attentional functions in schizophrenia

The aims of the current studies were to determine the in vitro and in vivo ocular and non-ocular pharmacological properties of cabergoline using well documented receptor binding, cell-based functional assays, and in vivo models. Cabergoline bound to native and/or human cloned serotonin-2A/B/C (5HT2A/B/C), 5HT1A, 5HT7, α2B, and dopamine-2/3 (D2/3) receptor subtypes with nanomolar affinity. Cabergoline was an agonist at human recombinant 5HT2, 5HT1A and D2/3 receptors but an antagonist at 5HT7 and α2 receptors. In primary human ciliary muscle (h-CM) and trabecular meshwork (h-TM) cells, cabergoline stimulated phosphoinositide (PI) hydrolysis (EC50 = 19 ± 7 nM in TM; 76 nM in h-CM) and intracellular Ca2+ ([Ca2+]i) mobilization (EC50 = 570 ± 83 nM in h-TM; EC50 = 900 ± 320 nM in h-CM). Cabergoline-induced [Ca2+]i mobilization in h-TM and h-CM cells was potently antagonized by a 5HT2A-selective antagonist (M-100907, Ki = 0.29–0.53 nM). Cabergoline also stimulated [Ca2+]i mobilization more potently via human cloned 5HT2A (EC50 = 63.4 ± 10.3 nM) than via 5HT2B and 5HT2C receptors. In h-CM cells, cabergoline (1 μM) stimulated production of pro-matrix metalloproteinases-1 and -3 and synergized with forskolin to enhance cAMP production. Cabergoline (1 μM) perfused through anterior segments of porcine eyes caused a significant (27%) increase in outflow facility. Topically administered cabergoline (300–500 μg) in Dutch-belted rabbit eyes yielded 4.5 μM and 1.97 μM levels in the aqueous humor 30 min and 90 min post-dose but failed to modulate intraocular pressure (IOP). However, cabergoline was an efficacious IOP-lowering agent in normotensive Brown Norway rats (25% IOP decrease with 6 μg at 4 h post-dose) and in conscious ocular hypertensive cynomolgus monkeys (peak reduction of 30.6 ± 3.6% with 50 μg at 3 h post-dose; 30.4 ± 4.5% with 500 μg at 7 h post-dose). In ketamine-sedated monkeys, IOP was significantly lowered at 2.5 h after the second topical ocular dose (300 μg) of cabergoline by 23% (p < 0.02) and 35% (p < 0.004) in normotensive and ocular hypertensive eyes, respectively. In normotensive eyes, cabergoline increased uveoscleral outflow (0.69 ± 0.7 μL/min–1.61 ± 0.97 μL/min, n = 13; p < 0.01). However, only seven of the eleven ocular hypertensive monkeys showed significantly increased uveoscleral outflow. These data indicate that cabergoline's most prominent agonist activity involves activation of 5HT2, 5HT1A, and D2/3 receptors. Since 5HT1A agonists, 5HT7 antagonists, and α2 antagonists do not lower IOP in conscious ocular hypertensive monkeys, the 5HT2 and dopaminergic agonist activities of cabergoline probably mediated the IOP reduction observed with this compound in this species.

Laterality differences in quantitative and qualitative hooper performance

The Hooper Visual Organization Test (HVOT) is a measure of visuospatial processing commonly employed in neuropsychological assessment. Despite the well-documented relationship between visuospatial abilities and right hemisphere function, the literature has not supported a right hemisphere association with HVOT performance. The current study was conducted to examine laterality differences in HVOT performance. Sixty-seven geriatric stroke patients (44 right CVAs, 23 left CVAs) were administered the HVOT and the Mini-Mental State Exam (MMS). Results revealed significant differences between CVA groups for total score, with right CVA patients performing more poorly. Qualitative error analyses revealed highest frequencies for part responses and don't know/no response errors. Between-group differences were seen for part and unformed/unassociated errors (higher right CVA rates), and language-based errors (higher left CVA rates). Findings are consistent with theories of brain lateralization and suggest that whereas HVOT performance predominantly involves right hemisphere functions, left hemisphere dysfunction may also lead to impaired performance, and the two can be discriminated by qualitative analysis of errors.

Laterality differences in quantitative and qualitative hooper performance

The Hooper Visual Organization Test (HVOT) is a measure of visuospatial processing commonly employed in neuropsychological assessment. Despite the well-documented relationship between visuospatial abilities and right hemisphere function, the literature has not supported a right hemisphere association with HVOT performance. The current study was conducted to examine laterality differences in HVOT performance. Sixty-seven geriatric stroke patients (44 right CVAs, 23 left CVAs) were administered the HVOT and the Mini-Mental State Exam (MMS). Results revealed significant differences between CVA groups for total score, with right CVA patients performing more poorly. Qualitative error analyses revealed highest frequencies for part responses and don't know/no response errors. Between-group differences were seen for part and unformed/unassociated errors (higher right CVA rates), and language-based errors (higher left CVA rates). Findings are consistent with theories of brain lateralization and suggest that whereas HVOT performance predominantly involves right hemisphere functions, left hemisphere dysfunction may also lead to impaired performance, and the two can be discriminated by qualitative analysis of errors.

Crossed Aphasia. I: A Case-Study with Purely Deep Lesion

In this paper, we describe the case of a right-handed man, MR, who after right thalamic haemorrhage presented subtranscortical aphasia. Of the disturbances generally associated with standard left hemisphere functions, the patient presented acalculia but not apraxia. Among the functions attributed to the standard right hemisphere, MR showed impairment in affective language and presented unilateral neglect and a strong position preference.

Functional hemisphere imbalance in patients with paranoid or disorganized schizophrenia

We assessed hemisphere function in right-handed male chronic schizophrenic patients using dichotic listening tests. We evaluated digit, tonic and transitional tests in patients with paranoid schizophrenia (n = 8), patients with disorganized schizophrenia (n = 8) and in control subjects (n = 8). The dichotic listening analysis discriminated between paranoid and disorganized schizophrenia. In disorganized schizophrenia, functional impairment of both hemispheres was demonstrated, while in paranoid schizophrenia dysfunction was more prominent in the right hemisphere. These results indicate the possible involvement of right hemisphere dysfunction in the pathophysiology of chronic paranoid schizophrenia, in contrast to dysfunction of both hemispheres in chronic disorganized schizophrenia.

Comparison of intracranial self-stimulation evoked from lateral hypothalamus and ventral tegmentum: analysis based on stimulation parameters and behavioural response characteristics.

The comparison of intracranial self-stimulation (ICSS) derived across the anteroposterior axis of medial forebrain bundle (MFB) from the anterior border of lateral hypothalamus (LH) to the ventral mesencephalon including ventral tegmental area-substantia nigra (VTA-SN) in Wistar rats was assessed through stimulation parameters and behavioural response characteristics. The interpretation of response rate/charge consumption (muC/min) with respect to rectangular wave and sine wave electrical stimulation parameters suggests that the rectangular wave parameters are better in order to get the maximum responding rates. The most vigorous and robust responding was observed in the VTA or VTA-SN boundary placements, followed by placements in medial sector of LH. The acquisition of ICSS was fastest in the case of VTA-stimulation. The next site with respect to rapidity of ICSS was posterio-ventral LH. The extinction curves indicated that it is faster and exponential in case of VTA-SN, but it is slower with longer duration in case of LH-MFB. ICSS of SN were accompanied by exploratory locomotion and head bobbing. Thirty-one percent subjects with SN/VTA stimulation showed rotational behaviour. Seventy-eight percent of subjects with LH stimulations showed stimulus-bound ejaculations. Thirty-two percent of subjects with posterior LH stimulations showed biting of pedal edges. LH stimulations were accompanied by induced seizures and increased grooming in 18% and 13% of subjects, respectively. There was lateralisation of cerebral hemispheric function as right paw preference was noted in majority of rats, whether sites of stimulation were in the left or right cerebral hemisphere. The various other modes of pedal pressing operants like use of paw and mouth, alternate paw dribbling, use of head electrode assembly to manipulate the pedal were also recorded and analysed.

Effect of age on the line bisection test.

The purpose of this study was to investigate the effect of age on the line bisection test. One hundred and eight normal dextrals of various ages performed a line bisection task with each hand. They were divided into three different age groups of 36 individuals. The old age group bisected lines significantly further to the right than did the middle and young age groups. Results on the line bisection test of the middle and the young age group were not different. Our results are discussed with reference to the theory of asymmetrical decline or maturing of the hemispheric functions over age.

Personal Name Recognition and Associative Priming in Patients with Unilateral Brain-Damage

This study investigated the performance of left- (LED) and right-brain-damaged (RBD) patients in recognizing personal names under different conditions of associative priming. Subjects performed speeded familiarity decisions for names of famous and unfamiliar persons, These target names were preceded by primes, either faces or names, which could be neutral, related (e.g. Gorbachev-Jelzin), or unrelated (e.g. Travolta-Carter), Overall impairments in name recognition were observed in both patient groups relative to controls but were more severe in LED than in RED patients, This suggests that, contrary to previous hypotheses, the recognition of personal names is more dependent on left hemisphere functioning. In controls and LED patients, associative priming effects did not differ significantly between face and name primes. In RED patients, however, associative priming from names was larger than priming from faces. This specificity of priming effects for names in RED patients was tentatively related to their impairments in face recognition.