Biology subjects

Ahs, F.

Publications and source records attributed to Ahs, F..

4 recordsLinked to original sources

bioRxiv2021

Whole Brain Correlates of Individual Differences in Skin Conductance Responses during Human Fear Conditioning

Understanding the neural basis for individual differences in the conditioned skin conductance response (SCR) may inform on autonomic regulation in fear-related psychopathology. Previous region-of-interest (ROI) analyses have implicated the amygdala in regulating conditioned SCR, but whole brain analyses are lacking. This study examined correlations between individual differences in conditioned SCR and neural activity throughout the whole brain by using data from a large functional magnetic resonance imaging study (N = 285). Results show that conditioned SCR correlates with activity in the dorsal anterior cingulate cortex/anterior midcingulate cortex, anterior insula, bilateral temporoparietal junction, right frontal operculum, bilateral dorsal premotor cortex, right superior parietal lobe and midbrain. A ROI analysis replicated a correlation between amygdala activity and conditioned SCR, but amygdala contribution to SCR was modest compared with other regions. We suggest that implicated neural regions belong to a large-scale midcingulo-insular network related to salience detection and autonomic-interoceptive processing. Altered activity within this network may underlie individual differences in conditioned SCR and autonomic aspects of psychopathology.

neuroscience↗

bioRxiv2021

Dopamine facilitates fear memory formation in the human amygdala

Learning which environmental cues that predict danger is crucial for survival and accomplished through Pavlovian fear conditioning. In humans and rodents alike, fear conditioning is amygdala-dependent and rests on similar neurocircuitry. Rodent studies have implicated a causative role for dopamine in the amygdala during fear memory formation, but the role of dopamine in aversive learning in humans is unclear. Here, we show dopamine release in the amygdala and striatum during fear learning in humans. Using simultaneous positron emission tomography and functional magnetic resonance imaging, we demonstrate that the amount of dopamine release is linked to strength of conditioned fear responses and linearly coupled to learning-induced memory trace activity in the amygdala. Thus, like in rodents, formation of amygdala-dependent fear memories in humans seems to be facilitated by endogenous dopamine release, supporting an evolutionary conserved neurochemical mechanism for aversive memory formation.

neuroscience↗

bioRxiv2021

Genetic influences on brain activation and large-scale functional connectivity during nociceptive processing: a twin study

Nociceptive processing in the human brain is a signal that enables harm avoidance, with large interindividual variance. The relative contributions of genes and environment to the neural structures that support nociception have not been studied in twins previously. Here, we employed a classic twin-design to determine brain structures influenced by additive genetics. We found genetic influences on nociceptive processing in the midcingulate cortex, bilateral posterior insulae and thalamus. In addition to brain activations, we found genetic contributions to large-scale functional connectivity during nociceptive processing. We conclude that additive genetics influence specific aspects of nociceptive processing, which improves our understanding of human nociceptive processing.

neuroscience↗

bioRxiv2020

GABA quantification in human anterior cingulate cortex

{gamma}-Aminobutyric acid (GABA) is a primary inhibitory neurotransmitter in the human brain. It has been shown that altered GABA concentration plays an important role in a variety of psychiatric and neurological disorders. The main purpose of this study was to propose a combination of PRESS and MEGA-PRESS acquisitions for absolute GABA quantification and to compare GABA estimations obtained using total choline (tCho), total creatine (tCr), and total N-acetyl aspartate (tNAA) as the internal concentration references with water referenced quantification. The second aim was to demonstrate the fitting approach of MEGA-PRESS spectra with QuasarX algorithm using a basis set of GABA, glutamate, glutamine, and NAA in vitro spectra. Thirteen volunteers were scanned with the MEGA-PRESS sequence at 3T. Interleaved water referencing was used for quantification, B0 drift correction and to update the carrier frequency of RF pulses in real time. Reference metabolite concentrations were acquired using a PRESS sequence with short TE (30 ms) and long TR (5000 ms). Absolute concentration were corrected for cerebrospinal fluid, gray and white matter water fractions and relaxation effects. Water referenced GABA estimations were significantly higher compared to the values obtained by metabolite references. We conclude that QuasarX algorithm together with the basis set of in vitro spectra improves reliability of GABA+ fitting. The proposed GABA quantification method with PRESS and MEGA-PRESS acquisitions enables the utilization of tCho, tCr, and tNAA as internal concentration references. The use of different concentration references have a good potential to improve the reliability of GABA estimation.

neuroscience↗