Biology subjects

Bahmani, Z.

Publications and source records attributed to Bahmani, Z..

3 recordsLinked to original sources

bioRxiv2026

Distinct tuning properties of human hippocampal neurons along the longitudinal axis during working memory

Working memory (WM) is among the most sophisticated and fundamental capabilities of the mammalian brain. While the roles of prefrontal and sensory areas are heavily explored, there is little knowledge on how the hippocampus (HPC) contributes to this process. Here, we studied human HPC neuronal activities during a verbal WM task and reveal that neurons in the posterior HPC (PH) show more robust rate-modulations during WM. On the other hand, anterior HPC (AH) neurons are more prominently modulated by the phase of local and frontal cortex {theta} and {beta} oscillations, a phenomenon that is accompanied by enhanced phase-synchronization between frontal cortex and HPC. Moreover, absence of correlational correspondence suggested that rate and phase are independent coding mechanisms. These results open a window to explore the functional dissociations along the primate HPC antero-posterior axis, a phenomenon long known to exist in the rodent brain. Furthermore, we suggest that combination of a variety of coding mechanisms in the human HPC neuronal population supports execution of WM.

neuroscience↗

bioRxiv2025

Spectral decomposition of local field potentials uncovers frequency-tuned gain modulation of working memory in primate visual system

Working memory has been shown to modulate visual processing in a variety of ways, including changes in visual response gain, oscillatory power, spike timing, and phase coding of information1-3. Here we probe working memorys influence on various oscillatory components within visual areas, using the Maximal Overlap Discrete Wavelet Transform (MODWT) technique to decompose the local field potential(LFP)4; this method allows single-trial quantification of the properties of various oscillatory components. We examine the impact of spatial working memory on visual processing within the extrastriate middle temporal (MT) visual area of rhesus macaque monkeys, comparing the responses in MT when remembering a location inside or outside the receptive fields of the neurons being recorded. Using traditional bandpass filtering, we replicate previous reports that working memory enhances visual responses, low-frequency oscillatory power, spike-phase locking, and phase coding of visual information. Applying the MODWT method, we find that working memory modulates both oscillatory power and the precise frequency of oscillations within a general frequency band. The precise frequency of several lower frequency components (alpha, theta, and beta frequencies, but not gamma or high gamma) correlates with visually-evoked firing rates of MT neurons on a trial-by-trial basis. This relationship between firing rate and oscillatory component frequency is maintained across memory conditions, indicating a close link between the neural mechanisms driving oscillatory frequency and firing rates.

neuroscience↗

bioRxiv2020

Frontotemporal Coordination Predicts Working Memory Performance and its Local Neural Signatures

Neurons in some sensory areas reflect the content of working memory (WM) in their spiking activity. However, this spiking activity is seldom related to behavioral performance. We studied the responses of inferotemporal (IT) neurons, which exhibit object-selective activity, along with Frontal Eye Field (FEF) neurons, which exhibit spatially-selective activity, during the delay period of an object WM task. Unlike the spiking activity and local field potentials (LFPs) within these areas, which were poor predictors of behavioral performance, the phase-locking of IT spikes and LFPs with the beta band of FEF LFPs robustly predicted successful WM maintenance. In addition, IT neurons exhibited greater object-selective persistent activity when their spikes were locked to the phase of FEF LFPs. These results demonstrate a key role of coordination between prefrontal and temporal cortex in the successful maintenance of visual information during WM.

neuroscience↗