Human Brain Research Papers - Academia.edu (original) (raw)

In this paper multivariate spontaneous EEG signals from three broad groups of human subjects--control, seizure, and mania--were studied with the aim of investigating the possible effect of these pathologies on the degree of phase... more

In this paper multivariate spontaneous EEG signals from three broad groups of human subjects--control, seizure, and mania--were studied with the aim of investigating the possible effect of these pathologies on the degree of phase synchronization between cortical areas. The degree of phase synchrony was measured by two recently developed measures which are more suitable than classical indices like correlation or coherence when dealing with nonlinear and non-stationary signals like the EEG. Signals were reduced to seven frequency bands (delta, theta, alpha-1, alpha-2, beta-1, beta-2 and gamma) which were statistically compared between the normal and the other two groups. It was found that the degree of long-range synchrony was significantly reduced for both pathological groups as compared with the control group. No clear differences were found in the degrees of short-range synchrony.

Increasing evidence implies the involvement of the dopamine (DA) system in the pathogenesis of alcoholism. We measured striatal DA D(2) receptors in Cloninger type 1 and 2 alcoholics by using [(125)I]epidepride in human postmortem whole... more

Increasing evidence implies the involvement of the dopamine (DA) system in the pathogenesis of alcoholism. We measured striatal DA D(2) receptors in Cloninger type 1 and 2 alcoholics by using [(125)I]epidepride in human postmortem whole hemispheric autoradiography (WHA), which provides high-resolution images corresponding to positron emission tomographic (PET) studies. We also evaluated the correlation between transporter and receptor DA binding site densities and putative correlation of [(125)I]epidepride binding between the dorsal striatum and nucleus accumbens. In the type 1 alcoholics, the DA D(2) receptor density was 21.4-32.6% lower in all dorsal striatal structures (caudate, putamen, globus pallidus) when compared with the controls. Type 2 alcoholics had 19.6-21.4% lower binding in other dorsal striatal structures, except medial globus pallidus, where they were not significantly different from controls. The density of DA D(2) receptors and DAT had a significant positive correlation only in the putamen of type 1 alcoholics. The binding of [(125)I]epidepride showed also consistent and statistically significant positive correlation between nucleus accumbens and all dorsal striatal areas in type 1 alcoholics but not in the controls. In the type 2 alcoholics, the correlation was weaker than that observed in the type 1 alcoholics, and no correlation was observed between nucleus accumbens and globus pallidus. Our results show that these two subgroups of alcoholics have stark differences in their DA D(2) receptor binding characteristics. Type 2 alcoholics may have selective deficiency in the dorsal striatum, whereas in limbic structures they may not differ significantly from controls. Moreover, WHA provides a useful tool for detailed mapping of neuronal receptors in healthy as well as diseased brain, and can also be used in radioligand development for PET.

Preparations of d,l- and meso-hexamethylpropyleneamine oxime (HM-PAO) labeled with technetium-99m were added to rat brain homogenates diluted with phosphate buffer (l: 10). The conversion of d,l-HM-PAO to hydrophilic forms took place with... more

Preparations of d,l- and meso-hexamethylpropyleneamine oxime (HM-PAO) labeled with technetium-99m were added to rat brain homogenates diluted with phosphate buffer (l: 10). The conversion of d,l-HM-PAO to hydrophilic forms took place with an initial rate constant of 0.12 min−1. Incubation of the brain homogenate with 2% diethyl maleate for 5 h decreased the homogenate's measured glutathione (GSH) concentration from 160 to 16 μ M and decreased the conversion rate to 0.012 min−1. Buffered aqueous solutions of glutathione rapidly converted the HM-PAO tracers to hydrophilic forms having the same chromatographic characteristics as found in the brain homogenates. The rate constant for the conversion reaction of d,l-HM-PAO in GSH aqueous solution was 208 and 317 L/mol/min in two different assay systems and for meso-HM-PAO the values were 14.7 and 23.2 L/mol/min, respectively. Rat brain has a GSH concentration of about 2.3 m M and the conversion of the d,l-HM-PAO due to GSH alone should...

Autism is a neurodevelopmental disorder that severely disrupts social and cognitive functions. MRI is the method of choice for in vivo and non-invasively investigating human brain morphology in children and adolescents. The authors... more

Autism is a neurodevelopmental disorder that severely disrupts social and cognitive functions. MRI is the method of choice for in vivo and non-invasively investigating human brain morphology in children and adolescents. The authors reviewed structural MRI studies that investigated structural brain anatomy and development in autistic patients. All original MRI research papers involving autistic patients, published from 1966 to May 2003, were reviewed in order to elucidate brain anatomy and development of autism and rated for completeness using a 12-item check-list. Increased total brain, parieto-temporal lobe, and cerebellar hemisphere volumes were the most replicated abnormalities in autism. Interestingly, recent findings suggested that the size of amygdala, hippocampus, and corpus callosum may also be abnormal. It is conceivable that abnormalities in neural network involving fronto-temporo-parietal cortex, limbic system, and cerebellum may underlie the pathophysiology of autism, and that such changes could result from abnormal brain development during early life. Nonetheless, available MRI studies were often conflicting and could have been limited by methodological issues. Future MRI investigations should include well-characterized groups of autistic and matched healthy individuals, while taking into consideration confounding factors such as IQ, and socioeconomic status.

Having a sense of self is an explicit and high-level functional specialization of the human brain. The anatomical localization of self-awareness and the brain mechanisms involved in consciousness were investigated by functional... more

Having a sense of self is an explicit and high-level functional specialization of the human brain. The anatomical localization of self-awareness and the brain mechanisms involved in consciousness were investigated by functional neuroimaging different emotional mental ...

We respond to Gallup’s (2020) opinion piece by indicating that psychologists have yet to agree on an operationalized definition of “intelligence.” We offer our understanding of the literature that a decline of human intelligence is... more

We respond to Gallup’s (2020) opinion piece by indicating that psychologists have yet to agree on an operationalized definition of “intelligence.” We offer our understanding of the literature that a decline of human intelligence is mixed; additionally, if a decline in human intelligence was supported, evolutionary scholars are not in a position to change the course of such decline. We clarify what evolutionary psychology is: the study of human nature by empirical examination of evidence for adaptive design hypotheses, but not a mission to preach and solve problems associated with evolutionary challenges. Finally, we dispute Gallup’s (2020) suggested proscription for evolutionary psychologists.

The purpose of this study was to evaluate the adequacy of coregistration of movement-related cortical potentials (MRCPs) and functional magnetic resonance imaging (fMRI) data in the primary sensorimotor cortex. Data were acquired in four... more

The purpose of this study was to evaluate the adequacy of coregistration of movement-related cortical potentials (MRCPs) and functional magnetic resonance imaging (fMRI) data in the primary sensorimotor cortex. Data were acquired in four normal subjects during right and left simple index finger movements. In fMRI (single-slice, 1.5 Tesla, T2*-weighted FLASH sequence), contralateral primary motor (M1) and primary sensory cortex (S1) were activated in all subjects. Spatiotemporal dipole modelling of electric MRCP generators (BESA) revealed two main sources in the central region contralateral to the moving finger. Both sources were tangentially oriented. Their configuration was consistent with source locations in the anterior (M1) and posterior (S1) banks of the central sulcus. Accordingly, the M1 source generated the pre-movement, the S1 source largely the immediate post-movement MRCP component. Taken together, MRCP modelling and fMRI data indicated a phasic sequential activation pattern of mostly sulcal portions of contralateral M1 and S1. After coregistration of anatomical MRI, fMRI, and dipole modelling results, the average 3D-distance between fMRI activation areas and MRCP source locations was 18.6 mm (SD 7.6), with the largest deviation in the anterior-posterior direction (12.1+/-9.5 mm). Coregistration inaccuracies of similar magnitude (approximately 17 mm) have been reported previously with MEG and PET or fMRI. We conclude, therefore, that the combination of EEG and fMRI is a promising technique for validation of electrophysiological source models and for evaluation of human functional brain anatomy with both adequate spatial and temporal resolution.

A machine for language? Certainly, say the neurophysiologists, busy studying the language specializations of the human brain and trying to identify their evolutionary antecedents. Linguists such as Noam Chomsky talk about machinelike... more

A machine for language? Certainly, say the neurophysiologists, busy studying the language specializations of the human brain and trying to identify their evolutionary antecedents. Linguists such as Noam Chomsky talk about machinelike "modules" in the brain for syntax, arguing that language is more an instinct (a complex behavior triggered by simple environmental stimuli) than an acquired skill like riding a bicycle. But structured language presents the same evolutionary problems as feathered forelimbs for flight: you need a lot of specializations to fly even a little bit. How do you get them, if evolution has no foresight and the intermediate stages do not have intermediate payoffs? Some say that the Darwinian scheme for gradual species self-improvement cannot explain our most valued human capability, the one that sets us so far above the apes, language itself. William Calvin and Derek Bickerton suggest that other evolutionary developments, not directly related to language...

The RP-HPLC method for a simultaneous separation and quantitation of the dinitrophenyl derivative of cystathionine (N,N'-di-DNP) in biological samples together with GSH, GSSG, cysteine and cystine,... more

The RP-HPLC method for a simultaneous separation and quantitation of the dinitrophenyl derivative of cystathionine (N,N'-di-DNP) in biological samples together with GSH, GSSG, cysteine and cystine, provides a very useful tool for investigation of the transsulfuration pathway in biological samples, at the same providing results which reflect the redox status (GSH/GSSG ratio) and the potential of the generation of H₂S. An application of the method for the study of the process of transsulfuration in various human brain regions shows the presence of cystathionine in all the investigated regions; it also demonstrates that cystathionine levels vary greatly between particular regions. The highest level in the thalamus and the lowest in the cerebellum were associated with respectively a low or high γ-cystathionase activity, and at the same time, a high cysteine and GSH level in the thalamus and a low value in the cerebellum. Based on the above results, one may suggest a regulatory mechanism responsible for inhibition of the CGL activity at high concentration values of cysteine and/or GSH. Simultaneous determinations of GSH and GSSG levels allow for determining the GSH/GSSG ratio, which reflects tissue redox status. The method may be also employed in determining the activity of γ-cystathionase and cystathionine-β synthase.

Vivid visual images can be voluntarily generated in our minds in the absence of simultaneous visual input. While trying to count the number of flowers in Van Gogh's Sunflowers, understanding a description or recalling a path, subjects... more

Vivid visual images can be voluntarily generated in our minds in the absence of simultaneous visual input. While trying to count the number of flowers in Van Gogh's Sunflowers, understanding a description or recalling a path, subjects report forming an image in their "mind's eye". Whether this process is accomplished by the same neuronal mechanisms as visual perception has long been a matter of debate. Evidence from functional imaging, psychophysics, neurological studies and monkey electrophysiology suggests a common process, yet there are patients with deficits in one but not the other. Here we directly investigated the neuronal substrates of visual recall by recording from single neurons in the human medial temporal lobe while the subjects were asked to imagine previously viewed images. We found single neurons in the hippocampus, amygdala, entorhinal cortex and parahippocampal gyrus that selectively altered their firing rates depending on the stimulus the subject...