Biology subjects

Bijanzadeh, M.

Publications and source records attributed to Bijanzadeh, M..

5 recordsLinked to original sources

bioRxiv2026

Individualized brain-body signatures of positive emotions revealed by large-scale multimodal neurophysiological recording

Using one of the most comprehensive multimodal biosensing datasets in affective research, densely sampled within individuals, we asked how emotions are instantiated in each person's brain and body. Four participants viewed 168 emotion-evoking videos during 128-channel EEG and 28 autonomic, ocular and facial recordings. Cross-validated elastic-net classifiers distinguished each of 15 positive and neutral emotions from baseline in every participant (mean accuracy 87-97%). We found that no emotion was predicted by a single marker and each reflected a multimodal ensemble of cortical and autonomic activity whose composition was largely person-specific. Yet physiology-derived groupings converged selectively with self-report; Interest-Awe-Amusement-Satisfaction and Entrancement-Aesthetic Appreciation recurred across individuals based on physiology. Across emotion groups, frontal and posterior delta, posterior alpha and electrodermal activity formed a shared backbone, plausibly reflecting affective and sensory engagement, whereas cardiovascular and facial signals varied between people. This framework yields individualized, objective neurophysiological indicators of emotion, potentially aiding personalized diagnosis.

neuroscience↗

bioRxiv2023

Size tuning of neural response variability in laminar circuits of macaque primary visual cortex

Surround suppression and neural response variability are two widespread cortical phenomena thought to facilitate and impede, respectively, information processing and perception. Typically, manipulations that elicit neural response suppression quench variability, an observation that has led some to suggest that these two phenomena may share a common origin. However, few studies have systematically examined the relationship between surround suppression and variability. Surround suppression is mediated by multiple circuits and mechanisms that depend on the size of the sensory stimulus, and cortical layer. Variability is also laminar dependent. To understand how surround suppression and variability may influence laminar processing, here we have used electrophysiological laminar recordings to examine how neural response variability and the shared variability among neurons are modulated by visual stimulus size across the layers of macaque primary visual cortex (V1). We find that surround suppression does not always quench variability. Instead, variability is tuned for stimulus size in a layer-dependent manner. In all layers, stimulation of the receptive field (RF) reduced neural response variability, and the shared variability among neurons, relative to their pre-stimulus values. As the stimulus was enlarged beyond the RF, to involve the near RF-surround, both neural response variability and shared variability further decreased in infragranular layers, but did not change in granular and supragranular layers. In contrast, larger stimuli involving the far RF-surround increased both neural response variability and shared variability, relative to their value for a stimulus matched to the RF size, in supragranular layers, but decreased them or did not change them in granular and infragranular layers. Surprisingly, we also found that visual stimuli smaller than the RF could increase variability relative to baseline values, particularly in granular and infragranular layers. Our results point to multiple laminar-specific circuits and mechanisms as the source of variability, and call for new models of neural response variability.

neuroscience↗

bioRxiv2020

Naturalistic affective behaviors decoded from spectro-spatial features of multi-day human intracranial recordings

Task-based studies have uncovered distributed neural networks that support emotions, but little is known about how these networks produce affective behaviors in non-laboratory, ecological settings. We obtained continuous intracranial electroencephalography (iEEG) recordings from the emotion network in 11 patients with epilepsy during multi-day hospitalizations. We coded naturalistic affective behaviors (spontaneous expressions of positive or negative affect) from 116 hours of time-locked video recordings obtained over multiple days from subjects hospital rooms and utilized data driven classifiers to determine whether we could decode naturalistic affective behaviors from the neural data. Results indicated that binary within-subject random forest models could decode positive and negative affective behaviors from affectless behaviors (behaviors lacking valence) with up to 93% accuracy. Across the emotion network, positive and negative affective behaviors were associated with increased high frequency activity and decreased lower frequency activity. The anterior insula, amygdala, hippocampus, and anterior cingulate cortex (ACC) made strong contributions to affective behaviors in general. In a subset of subjects, three-state decoders distinguished among the positive, negative, and affectless behaviors using the spectro-spatial features from the emotion network. This study demonstrates that multi-day, highly resolved iEEG recordings in cortical and deep brain structures can reveal the circuit-level physiology of affective behaviors. By measuring behavior in an ecologically valid setting, our findings provide novel insights into the spatially distributed dynamics of local neural populations underlying naturalistic affective behaviors. SignificancePrevious neuroimaging and neurophysiological studies have identified a distributed network that supports emotions, but much remains unknown about how this network produces affective behaviors in ecological settings. We used intracranial electroencephalography recordings from the emotion network to decode naturalistic affective behaviors--spontaneous expressions of positive and negative affect that occurred during multi-day hospital stays--from neural data in patients with epilepsy. Our results complement prior neuroscientific studies of emotion and offer novel insights into the spectral and spatial dynamics of the emotion network that characterize naturalistic affective behaviors. The present study suggests intracranial electroencephalography can uncover new details about emotion network physiology and help to expand current neuroanatomical frameworks of human emotions.

neuroscience↗

bioRxiv2017

Distinct Laminar Processing of Local and Global Context in Primate Primary Visual Cortex

Visual perception is profoundly affected by spatial context. In visual cortex, neuronal responses to stimuli inside their receptive field (RF) are suppressed by contextual stimuli in the RF surround (surround suppression). How do neuronal RFs integrate information across visual space, and what role do different cortical layers play in the processing of spatial context? By recording simultaneously across all layers of macaque primary visual cortex, while presenting visual stimuli at increasing distances from the recorded cells RF, we find that near vs. far stimuli activate distinct layers. Stimuli in the near-surround evoke the earliest subthreshold responses in superficial and deep layers, and cause the earliest surround suppression of spiking responses in superficial layers. Instead, far-surround stimuli evoke the earliest subthreshold responses in feedback-recipient layers, i.e. 1 and the lower half of the deep layers, and suppress visually-evoked spiking responses almost simultaneously in all layers, except 4C, where suppression emerges latest. Our results reveal unique contributions of the cortical layers to the processing of local and global spatial context, and suggest distinct underlying circuits for local and global signal integration.

neuroscience↗

bioRxiv2016

CORTICO-CORTICAL FEEDBACK CONTROLS SPATIAL SUMMATION IN PRIMATE VISUAL CORTEX

In the cerebral cortex, sensory information travels along feedforward connections through a hierarchy of areas, which, in turn, send a denser network of feedback connections to lower-order areas. Feedback has been implicated in attention, expectation, and sensory context, but the cellular mechanisms underlying these diverse feedback functions are unknown. Using specific optogenetic inactivation of feedback connections in the primate visual cortex, we have identified the cellular mechanisms of feedback-mediated modulations of early sensory processing. Specifically, we found that feedback modulates receptive field size, surround suppression and response gain, similar to the modulatory effects of visual spatial attention. A recurrent network model captured these effects. These feedback-mediated modulations allow higher-order cortical areas to dynamically regulate spatial resolution, sensitivity to image features, and efficiency of coding natural images in lower-order cortical areas.

neuroscience↗