Biology subjects

Tal, I.

Publications and source records attributed to Tal, I..

6 recordsLinked to original sources

bioRxiv2026

Classification of image category based on spatially distributed, transient high-frequency events

Transient high-frequency activity (HFA) in local field potentials exhibits substantial variability across trials and behavioral states, yet its functional role in sensory representation remains poorly understood. Here, we tested whether transient HFA events carry stimulus-related information through their temporal, spectral, and phase-dependent properties. Using intracranial recordings from 21 human participants performing a visual localizer task, we extracted transient HFA events and quantified their features using information-theoretic and decoding analyses. Individual event features carried only modest information about stimulus identity, and response magnitude and morphology-related properties contributed minimally to decoding performance. Instead, decoding was dominated by temporal alignment and low-frequency phase. Critically, representing transient events as distributed low-frequency phase configurations across electrodes substantially improved cross-trial decoding performance, whereas disrupting distributed phase structure eliminated this decoding advantage. These findings indicate that stimulus-related structure in transient HFA does not primarily arise from isolated local event properties, but instead emerges through distributed, phase-dependent network dynamics. More broadly, the results provide a framework for understanding how transient high-frequency neural activity contributes to sensory representations across distributed cortical networks.

neuroscience↗

bioRxiv2025

Triphenylphosphonium is an effective targeting moiety for plants mitochondria

Small signaling molecule regulates key physiological processes in plants, often in a spatially distinct manner. However, current methods for applying small-molecules, endogenous or synthetic, in plants research lack spatial precision, limiting the ability to study and utilize their localized effects. Here, we validate triphenylphosphonium (TPP) as a mitochondrial targeting motif in plants. Using fluorescently labeled TPP conjugates in Arabidopsis thaliana, we demonstrate mitochondria-specific accumulation, even in the presence of plastids. This precise localization enables detailed imaging of mitochondria and mitochondrial DNA in living plants. We further exploit this targeting ability by developing a TPP-ciprofloxacin conjugate to selectively inhibit mitochondrial DNA gyrase, an enzyme involved in organellar DNA replication. Unlike free ciprofloxacin, which disrupts both mitochondrial and chloroplast DNA gyrase activity, the TPP-conjugate specifically targets mitochondrial gyrase, leading to slower plant growth without affecting chloroplast function. This targeted inhibition triggers a mitochondrial retrograde response, characterized by increased reactive oxygen species levels and the upregulation of stress-response genes in the nucleus. Our findings establish TPP as a reliable tool for mitochondrial targeting in plants and open avenues for both fundamental research and agricultural applications. By enabling organelle-specific manipulation in species not amenable to genetic engineering, TPP-based strategies have potential for advancing plant biology and precision agriculture.

plant biology↗

bioRxiv2022

Enterobacteriaceae isolated from patients share antibiotic resistance conferring plasmids recently acquired from those isolated from sinks in the same treatment room

Identifying how and where pathogens acquire antibiotic resistance is crucial to developing effective strategies to limit its spread. Many bacterial species carry and share plasmids harboring antibiotic resistant genes. Plasmids are mobile genetic elements whose horizontal transmission is difficult to assess through genomic comparison due to assembly issues when using short-read sequencing alone. In this study, we use hybrid assembly to fully assemble plasmids that are shared between different Enterobacteriaceae isolated from patients and sinks in the same hospital rooms. We isolated and sequenced pairs of carbapenem resistant Enterobacter hormaechei subsp. xiangfangensis and Klebsiella pneumoniae from patients and sinks within the same hospital room. The isolate pairs share plasmids that putatively confer antibiotic resistance, including carbapenem resistance. These plasmids differ by few mutations and structural changes, while the isolates carry unique plasmids. Together, this suggests that plasmids can act as vectors of antibiotic resistance spread from sink reservoirs to patients.

microbiology↗

bioRxiv2020

Does the phase of ongoing EEG oscillations predict auditory perception?

Effective processing of information from the environment requires the brain to selectively sample relevant inputs. The visual perceptual system has been shown to sample information rhythmically, oscillating rapidly between more and less input-favorable states. Evidence of parallel effects in auditory perception is inconclusive. Here, we combined a bilateral pitch-identification task with electroencephalography (EEG) to investigate whether the phase of ongoing EEG predicts auditory discrimination accuracy. We compared prestimulus phase distributions between correct and incorrect trials. Shortly before stimulus onset, each of these distributions showed significant phase concentration, but centered at different phase angles. The effects were strongest in theta and beta frequency bands. The divergence between phase distributions showed a linear relation with accuracy, accounting for at least 10% of inter-individual variance. Discrimination performance oscillated rhythmically at a rate predicted by the neural data. These findings indicate that auditory discrimination threshold oscillates over time along with the phase of ongoing EEG activity. Thus, it appears that auditory perception is discrete rather than continuous, with the phase of ongoing EEG oscillations shaping auditory perception by providing a temporal reference frame for information processing.

neuroscience↗

bioRxiv2020

Environmental shedding of toxigenic Clostridioides difficile by asymptomatic carriers: A prospective observational study

ObjectivesTo compare the burden of environmental shedding of toxigenic C. difficile among asymptomatic carriers, C. difficile infected (CDI) patients and non-carriers, in an inpatient non-epidemic setting. MethodsC. difficile carriage was determined by positive toxin-B PCR from rectal swabs of asymptomatc patients. Active CDI was defined as a positive 2-step EIA/PCR test in patients with >3 unformed stools/24 hours. C. difficile environmental contamination was assessed by obtaining specimens from 10 sites in the patients rooms. Toxigenic strains were identified by PCR. We created a contamination scale to define the overall level of room contamination that ranged from clean to heavy contamination. Results117 rooms were screened; 70 rooms inhabited by C. difficile carriers, 30 rooms by active CDI patients and 17 rooms by non C. difficile -carriers (Control). In the carrier rooms 29 (41%) had more than residual contamination, from which 17 (24%) were heavily contaminated. In the CDI rooms 12 (40%) had more than residual contamination from which 3 (10%) were heavily contaminated, while in the control rooms, one room (6%) had more than residual contamination and none were heavily contaminated. In a multivariate analysis, the contamination score of rooms inhabited by carriers did not differ from rooms of CDI patients, yet both were significantly more contaminated than those of none carriers OR 12.23 and 11.16 (95%CI:1.5-99.96 P=0.0195, and 1.19-104.49 p=0.035), respectively. ConclusionHere we show that C. difficile carriers rooms are as contaminated as those of patients with active CDI and significantly more than those of non-carriers.

microbiology↗

bioRxiv2019

Dissociation of broadband high-frequency activity and neuronal firing in the neocortex

Broadband High-frequency Activity (BHA; 70-150 Hz), also known as \"high gamma,\" a key analytic signal in human intracranial recordings is often assumed to reflect local neural firing (multiunit activity; MUA). Accordingly, BHA has been used to study neuronal population responses in auditory (1,2), visual (3,4), language (5), mnemonic processes (6-9) and cognitive control (10,11). BHA is arguably the electrophysiological measure best correlated with the Blood Oxygenation Level Dependent (BOLD) signal in fMRI (12-13). However, beyond the fact that BHA correlates with neuronal spiking (12, 14-16), the neuronal populations and physiological processes generating BHA are not precisely defined. Although critical for interpreting intracranial signals in human and non-human primates, the precise physiology of BHA remains unknown. Here, we show that BHA dissociates from MUA in primary visual and auditory cortex. Using laminar multielectrode data in monkeys, we found a bimodal distribution of stimulus-evoked BHA across depth of a cortical column: an early-deep, followed by a later-superficial layer response. Only, the early-deep layer BHA had a clear local MUA correlate, while the more prominent superficial layer BHA had a weak or undetectable MUA correlate. In many cases, particularly in V1 (70%), supragranular sites showed strong BHA in lieu of any detectable increase in MUA. Due to volume conduction, BHA from both the early-deep and the later-supragranular generators contribute to the field potential at the pial surface, though the contribution may be weighted towards the late-supragranular BHA. Our results demonstrate that the strongest generators of BHA are in the superficial cortical layers and show that the origins of BHA include a mixture of the neuronal action potential firing and dendritic processes separable from this firing. It is likely that the typically-recorded BHA signal emphasizes the latter processes to a greater extent than previously recognized.

neuroscience↗