Covert spatial attention (without concurrent eye movements) improves performance in many visual tasks (e.g., orientation discrimination and visual search). However, both covert attention systems—endogenous (voluntary) and exogenous (involuntary)—exhibit differential effects on performance in tasks mediated by spatial and temporal resolution suggesting an underlying mechanistic difference. We investigated whether these differences manifest in sensory tuning by assessing whether and how endogenous and exogenous attention differentially alter the representation of two basic visual dimensions–orientation and spatial frequency (SF). The same human observers detected a grating embedded in noise in two separate experiments (with endogenous or exogenous attention cues). Reverse correlation was used to infer the underlying neural representation from behavioral responses, and we linked our results to established neural computations via a normalization model of attention. Both endogenous and exogenous attention simil...

In presynaptic terminals, membrane-delimited Gi/o-mediated presynaptic inhibition is ubiquitous and acts through Gβγ to inhibit Ca2+ entry, or directly at SNARE complexes to inhibit Ca2+-dependent synaptotagmin-SNARE complex interactions. At CA1-subicular presynaptic terminals 5-HT1B and GABAB receptors colocalize. GABAB receptors inhibit Ca2+ entry, whereas 5-HT1B receptors target SNARE complexes. We demonstrate in male and female rats that GABAB receptors receptors alter Pr, whereas 5-HT1B receptors reduce evoked cleft glutamate concentrations allowing differential inhibition of AMPA and NMDA receptor EPSCs. This reduction in cleft glutamate concentration was confirmed by imaging glutamate release using a genetic sensor (iGluSnFR).Simulations of glutamate release and postsynaptic glutamate receptor currents were made. We tested effects of changes in vesicle numbers undergoing fusion at single synapses, relative placement of fusing vesicles and postsynaptic receptors, and the rate of release of glutamate ...

Primates explore their visual environment by making frequent saccades , discrete and ballistic eye movements that direct the fovea to specific regions of interest. Saccades produce large and rapid changes in input. The magnitude of these changes and the limited signaling range of visual neurons means that effective encoding requires rapid adaptation. Here, we explore how macaque cone photoreceptors maintain sensitivity under these conditions. Adaptation makes cone responses to naturalistic stimuli highly nonlinear and dependent on stimulus history. Such responses cannot be explained by linear or linear-nonlinear models but are well explained by a biophysical model of phototransduction based on well-established biochemical interactions. The resulting model can predict cone responses to a broad range of stimuli and enables the design of stimuli that elicit specific (e.g. linear) cone photocurrents. These advances will provide a foundation for investigating the contributions of cone phototransduction and post...

Sensory experience during a critical period alters sensory cortical responses and organization. We find that the earliest sound-driven activity in the mouse auditory cortex (ACX) starts before ear-canal opening (ECO). The effects of auditory experience before ECO on ACX development are unknown. We find that in mouse ACX Subplate neurons (SPNs), crucial in thalamocortical maturation, respond to sounds before ECO showing oddball selectivity. Before ECO, SPNs are more selective to oddball sounds in auditory streams than thalamo-recipient Layer 4 (L4) neurons and not after ECO. We hypothesize that SPN’s oddball selectivity can direct the development of L4 responses before ECO. Exposing mice, of either sex, before ECO to a rarely occurring tone in a stream of another tone occurring frequently leads to strengthening the adult cortical representation of the rare tone, but not that of the frequent tone. Results of control exposure experiments at multiple developmental windows that also use only a single tone corro...

Category learning—learning to sort a set of stimuli into categories or groups—can induce category biases in perception such that items in the same category are perceived as more similar than items from different categories. To what degree category bias develops when learning goals emphasize individuation of each stimulus and whether the bias emerges spontaneously during learning itself rather than in response to task demands is unclear. Here, we used functional MRI during encoding to test for category biases in neural representations of individual stimuli during learning. Human participants (males and females) encountered face-blend stimuli with unique first names and shared family names that indicated category membership. Participants were instructed to learn the full name for each face. Neural pattern classification and pattern similarity analyses were used to track category information in the brain. Results showed that stimulus category could be decoded during encoding across many frontal, parietal and ...

Economic choice is thought to involve the elicitation of the subjective values of the choice options. Thus far, value estimation in animals has relied upon stochastic choices between multiple options presented in repeated trials and expressed from averages of dozens of trials. However, subjective reward valuations are made moment-to-moment and do not always require alternative options; their consequences are usually felt immediately. Here we describe a Becker-DeGroot-Marschak (BDM) auction-like mechanism that provides more direct and simple valuations with immediate consequences. The BDM encourages agents to truthfully reveal their true subjective value in individual choices ('incentive compatibility'). Male monkeys reliably placed well-ranked BDM bids for up to five juice volumes while paying from a water budget. The bids closely approximated the average subjective values estimated with conventional binary choices, thus demonstrating procedural invariance and aligning with the wealth of knowledge acquired...

How do animals adopt a given behavioral strategy to solve a recurrent problem when several effective strategies are available to reach the goal? Here we provide evidence that striatal cholinergic interneurons (SCIN) modulate their activity when mice must select between different strategies with similar goal-reaching effectiveness. Using a cell-type specific transgenic murine system, we show that adult SCIN ablation impairs strategy selection in navigational tasks where a goal can be independently achieved by adopting an allocentric or egocentric strategy. SCIN-depleted mice learn to achieve the goal in these tasks, irrespective of their appetitive or aversive nature, similarly to controls. However, they cannot shift away from their initially adopted strategies as control mice do as training progresses. Our results indicate that SCIN are required for shaping the probability function used for strategy selection as experience accumulates throughout training. Thus, SCIN may be critical for resolution of cognit...

One of the very first observations made regarding alpha oscillations (8–14 Hz), is that they increase in power over posterior areas when awake participants close their eyes. Recent work, especially in the context of (spatial) attention, suggests that alpha activity reflects a mechanism of functional inhibition. However, it remains unclear how eye closure impacts anticipatory alpha modulation observed in attention paradigms, and how this affects subsequent behavioral performance. Here, we recorded magnetoencephalography (MEG) in 33 human participants performing a tactile discrimination task with their eyes open vs. closed. We replicated the hallmarks of previous somatosensory spatial attention studies: alpha lateralization across the somatosensory cortices as well as alpha increase over posterior (visual) regions. Furthermore, we found that eye closure leads to (i) reduced task performance, (ii) widespread increase in alpha power, and (iii) reduced anticipatory visual alpha modulation (iv) with no effect on...

The human amygdala and hippocampus are critically involved in various processes in face perception. However, it remains unclear how task demands or evaluative contexts modulate processes underlying face perception. In this study, we employed two task instructions when participants viewed the same faces and recorded single-neuron activity from the human amygdala and hippocampus. We comprehensively analyzed task modulation for three key aspects of face processing and we found that neurons in the amygdala and hippocampus (1) encoded high-level social traits such as perceived facial trustworthiness and dominance and this response was modulated by task instructions; (2) encoded low-level facial features and demonstrated region-based feature coding, which was not modulated by task instructions; and (3) encoded fixations on salient face parts such as the eyes and mouth, which was not modulated by task instructions. Together, our results provide a comprehensive survey of task modulation of neural processes underly...

Insight into the cellular and circuit mechanisms underlying development of temporal lobe epilepsy will provide a foundation for improved therapies. We studied a model in which an episode of prolonged seizures is followed by recovery lasting two weeks before emergence of spontaneous recurrent seizures. We focused on the interval between the prolonged seizures and the late onset recurrent seizures. We investigated the hippocampal mossy fiber CA3 pyramidal cell microcircuit in models spanning in vitro , in vivo , and ex vivo preparations. Expression of channelrhodopsin-2 in the dentate granule cells of DGC ChR mice enabled the selective activation of mossy fiber axons. In vivo studies revealed marked potentiation of mossy fiber evoked field potentials in hippocampal CA3 beginning within hours following seizures, a potentiation which persisted at least seven days. Stimulation of mossy fibers in hippocampal slices in vitro using patterns of activity mimicking seizures induced LTP not only of the monosynaptic EP...