Biology subjects

Furman-Haran, E.

Publications and source records attributed to Furman-Haran, E..

9 recordsLinked to original sources

bioRxiv2026

A cortical hierarchy of sensory representations from physical structure to idiosyncratic perception

Perception begins with the physical structure of the external world, yet each of us remaps that structure into an idiosyncratic ordering shaped by individual experience and makeup. To ask how these two orderings are reflected in the brain, we used fMRI in 47 participants to measure the representation of olfactory and visual stimuli chosen such that similarities among the odorants mirrored those among the images. Olfactory and visual cortices each reflected physical similarity more strongly than idiosyncratic perceptual similarity. By contrast, a whole-brain search for the alternative uncovered the left angular gyrus, which reflected idiosyncratic perceptual similarity in both olfaction and vision. Connectivity analysis depicted this region as a likely hub for such representation, and dynamic causal modeling supported this observation. These findings reveal a transition from stimulus-centered representations in modality-specific sensory cortex to a modality-general observer-centered representation in the angular gyrus, suggesting a potentially fundamental hierarchy in brain organization.

neuroscience↗

bioRxiv2024

Inhibitory mechanisms in the prefrontal-cortex differentially mediate Putamen activity during valence-based learning

Learning from appetitive and aversive stimuli involves interactions between the prefrontal cortex and subcortical structures. Preclinical and theoretical studies indicate that inhibition is essential in regulating the relevant neural circuitry. Here, we demonstrate that GABA, the main inhibitory neurotransmitter in the central nervous system, differentially affects how the dACC interacts with subcortical structures during appetitive and aversive learning in humans. Participants engaged in tasks involving appetitive and aversive learning, while using functional magnetic resonance spectroscopy (MRS) at 7T to track GABA concentrations in the dACC, alongside whole-brain fMRI scans to assess BOLD activation. During appetitive learning, dACC GABA concentrations were negatively correlated with learning performance and BOLD activity measured from the dACC and the Putamen. These correlations were absent during aversive learning, where dACC GABA concentrations negatively correlated with the connectivity between the dACC and the Putamen. Our results show that inhibition in the dACC mediates appetitive and aversive learning in humans through distinct mechanisms.

neuroscience↗

bioRxiv2023

Increased cortical inhibition immediately following brief motor memory reactivation supports reconsolidation and overnight offline learning gains

Practicing motor skills stabilizes and strengthens motor memories by repeatedly reactivating and reconsolidating them. The conventional view, by which a repetitive practice is required for substantially improving skill performance, has been recently challenged by behavioral experiments, in which even brief reactivations of the motor memory have led to significant improvements in skill performance. However, the mechanisms which facilitate brief reactivation-induce skill improvements remain elusive. While initial memory consolidation has been repeatedly associated with increased neural excitation and dis-inhibition, reconsolidation has been shown to involve a poorly-understood mixture of both excitatory and inhibitory alterations. Here, we followed a three-day reactivation-reconsolidation framework, to examine whether the excitatory/inhibitory mechanisms which underlie brief reactivation and repetitive practice differ. Healthy volunteers practiced a motor sequence learning task using either brief reactivation or repetitive practice and were assessed using ultra-high field (7T) magnetic resonance spectroscopy at the primary motor cortex (M1). We found that increased inhibition (GABA concentrations) and decreased excitation/inhibition (glutamate/GABA ratios) immediately following the brief reactivation were associated with overnight offline performance gains. These gains were on-par with those exhibited following repetitive practice, where no correlations with inhibitory or excitatory changes were observed. Our findings suggest that brief reactivation and repetitive practice depend on fundamentally different neural mechanisms, and that early inhibition - and not excitation - is particularly important in supporting the learning gains exhibited by brief reactivation.

neuroscience↗

bioRxiv2022

Early excitatory and inhibitory modifications in the motor cortex following skill learning support motor memory consolidation and cortical plasticity overnight

The learning of new motor skills constitutes an inseparable part of our lives. Motor consolidation refers to the offline processing of motor memories following the acquisition of new motor skills. The animal literature suggests that the primary motor cortex (M1) plays a key role in motor memory consolidation, and structural and functional plasticity in M1 following motor consolidation have been demonstrated. However, the mechanisms supporting motor memory consolidation and plasticity in the human M1 are not well understood. Initial human neuroimaging studies show that the initial stages of motor learning in humans are accompanied by short-term temporal dynamics of the brains main excitatory and inhibitory neurotransmitters - Glutamate (Glu) and GABA - in M1, but it remains unclear how these relate to the question of motor memory consolidation. Here, we show that early Glu and GABA modifications in M1 following motor skill learning may play vital roles in supporting motor memory consolidation and neural plasticity that take place over longer time scales. Using a multimodal magnetic resonance approach implemented on ultra-high field 7T scanner in healthy young adults (n=36), we found increased Glu and decreased GABA in M1 during the initial offline period following learning to support consolidation-related local and inter-regional functions of M1, such as motor memory reactivation and increased functional connectivity with the striatum. These neurochemical changes also correlated with overnight structural and functional plasticity expressed as increased M1 grey matter volume and functional connectivity, while Glu modifications also correlated with adaptive behavior, as reflected by improvements in skill performance. Our results provide intriguing microscale mechanistic evidence to the potential distinctive roles of Glu and GABA in promoting motor memory consolidation and plasticity in the human M1. They also highlight a role for early neurochemical modifications to memory consolidation and plasticity in the human brain and may hold important clinical implications in rehabilitative settings such as in stroke and brain injury.

neuroscience↗

bioRxiv2020

Reducing SAR in 7T brain fMRI by circumventing fat suppression while removing the lipid signal through a parallel acquisition approach

Ultra-high-field functional magnetic resonance imaging (fMRI) offers the way to new insights while increasing the spatial and temporal resolution. However, a crucial concern in 7T human MRI is the increase in power deposition, supervised through the specific absorption rate (SAR). The SAR limitation can restrict the brain coverage or the minimal repetition time of fMRI experiments. fMRI is based on the well-known gradient-echo echo-planar imaging (GRE-EPI) sequence, which offers ultrafast acquisition. Commonly, the GRE-EPI sequence comprises two pulses: fat suppression and excitation. This work provides the means for a significant reduction in the SAR by circumventing the fat-suppression pulse. Without this fat-suppression, however, lipid signal can result in artifacts due to the chemical shift between the lipid and water signals. Our approach exploits a reconstruction similar to the simultaneous-multi-slice (SMS) method to separate the lipid and water images, thus avoiding undesired lipid artifacts in brain images. The lipid-water separation is based on the known spatial shift of the lipid signal, which can be detected by the multi-channel coils sensitivity profiles. Our study shows robust human imaging, offering greater flexibility to reduce the SAR, shorten the repetition time or increase the volume coverage with substantial benefit for brain functional studies.

neuroscience↗

bioRxiv2020

A Human Aggression Pheromone Elicits a Sexually Dimorphic Behavioral and Brain Response

Body-volatiles can effectively trigger or block conspecific aggression in terrestrial mammals. Here we tested whether hexadecanal (HEX), a human body-volatile implicated as a mammalian-wide social cue, impacts human aggression. Using validated behavioural paradigms, we observed a remarkable dissociation: sniffing HEX blocked aggression in men, but triggered aggression in women. Next, using functional brain imaging, we uncovered a pattern of brain activity mirroring behaviour: In both men and women, HEX increased activity in the left angular gyrus, an area implicated in perception of social cues. Hex then modulated functional connectivity between the angular gyrus and a brain network implicated in social appraisal (temporal pole) and aggressive execution (amygdala and orbitofrontal cortex) in a sex-dependent manner consistent with behaviour: increasing connectivity in men, but decreasing connectivity in women. These findings implicate sex-specific social chemosignaling at the mechanistic heart of human aggressive behaviour.

neuroscience↗

bioRxiv2020

Unexplained Repeated Pregnancy Loss is Associated with Altered Perceptual and Brain Responses to Men's Body-Odor

In the Bruce effect, pregnant mice remember the odor of the fathering male, and miscarry in response to the odor of a male stranger. Humans experience a high rate of unexplained spontaneous miscarriage. Could it be that a portion of these miscarriages reflect a Bruce-like effect? Given ethical constraints on a direct test, we instead probed for circumstantial evidence in women with repeated pregnancy loss (RPL). Consistent with a Bruce-like effect, women with RPL remembered the body-odor of their spouse, but controls could not. Also consistent with a Bruce-like effect, body-odor from a stranger man caused increased activity in the hypothalamus of women experiencing RPL, yet decreased activity in the hypothalamus of women controls. Finally, RPL was associated with reduced olfactory-bulb volume. Although not causal, these observations link RPL with an altered behavioral and brain response to mens body-odor, implicating the olfactory system in this poorly understood or managed condition.

physiology↗

bioRxiv2019

Studying the precuneus reveals structure-function-affect correlation in long-term meditators

Understanding the relationship between brain structure, function and self-reports has hardly been addressed until now in meditation research. Here we demonstrate such relationship, using Mindfulness meditation (MM). MM aims to reduce thought-related processes and enhance bodily awareness, thereby reducing identification with thought content and deconstructing maladaptive self-schema. We thus hypothesized that structure of the default mode network (DMN) regions, associated with spontaneous thoughts and self-representation, would negatively correlate with MM experience and self-reported positive affect, while positively correlating with DMN resting-state function.\n\nCross-sectionally comparing a unique group of adept MM practitioners and meditation-naive matched controls using voxel based morphometry revealed that gray matter (GM) density of the left precuneus (L-Prc) was negatively correlated with MM expertise. Furthermore, GM density of the L-Prc was positively correlated with resting state and task related functional (fMRI) measures within the L-Prc in the MM practitioners, but not in the controls. Finally, the L-Prcs GM density negatively correlated with positive affect across all participants.\n\nOur findings may shed light on understanding structure-function-self reports relationship. While our approach enables studying suggestive correlations in expert MM practitioners, longitudinal studies are required for direct insights concerning the question of causality.\n\nSignificance statementUnderstanding the relationship between brain structure and function, individual differences and self-reports, is an important goal of neuroscience. Yet, these factors were hardly investigated together in meditation research. The precuneus is part of the default mode network (DMN) involved in thought related processes. Mindfulness meditation (MM) is a mental practice aiming to reduce thought related processes. Here, by cross-sectionally comparing adept meditators and controls, we found that in the precuneus of MM practitioners, structure associated with function. Overall, structure negatively correlated with practice length, as well as with positive affect scores. The structure-function correlation was only significant in the meditators group, possibly implying that prolonged meditation improved structure and function attunement in the DMN. More generally, this study demonstrates that mental practice can be related to conjoint structural and functional effects, as well as to affective self-reports.

neuroscience↗

bioRxiv2019

Inter-thinker consistency of language activations during abstract thoughts

Human brain imaging typically employs structured and controlled tasks to avoid variable and inconsistent activation patterns. Here we argue against this assumption by showing that an extremely open-ended, high level cognitive task-loosely defined as "abstract thinking" leads to a precise, and highly consistent activation maps. Thus we show that activation maps generated during such cognitive process were precisely located relative to borders of well-known networks such as internal speech, visual and motor imagery. The activation patterns allowed decoding the thought condition at >95%. Surprisingly, the activated networks remained the same regardless of changes in thought content. Finally, we found a remarkably consistent activation map across individuals engaged in abstract thinking. The activation to abstract thinking bordered, but strictly avoided visual and motor networks. On the other hand, it partly overlapped with left lateralized language networks. These observations were supported by a quantitative neuronal distance metric analysis. Our results reveal that despite its high level, and varied content nature-abstract thinking activates surprisingly precise and consistent networks in the participants brains. Thinker refers to: The agent of thought; Intellectual, one who tries to use his or her intellect to work, study, reflect, speculate on, or ask and answer questions with regard to a variety of different ideas" (Wikipedia).

neuroscience↗