A consensus definition for deep layer 6 excitatory neurons in mouse neocortex.

To understand neocortical function, we must first define its cell types. Recent studies indicate that neurons in the deepest cortical layer play roles in mediating thalamocortical interactions and modulating brain state and are implicated in neuropsychiatric disease. However, understanding the functions of deep layer 6 (L6b) neurons has been hampered by the lack of agreed upon definitions for these cell types.

Mini-Symposium: Training the Trainers of the Next Generation of Neuroscience Advocates.

Undergraduate neuroscience researchers and educators have a vital voice in working with policymakers to raise public awareness and increase support and funding for neuroscience. While there are many avenues and opportunities to become involved in neuroscience advocacy, finding the most effective training strategies, resources, and opportunities for involvement can sometimes be difficult and overwhelming. To address this challenge and inform faculty of science advocacy opportunities for undergraduates, we organized a mini-symposium at the 2023 Faculty for Undergraduate Neuroscience (FUN) Workshop.

The Synaptic Organization of Layer 6 Circuits Reveals Inhibition as a Major Output of a Neocortical Sublamina.

The canonical cortical microcircuit has principally been defined by interlaminar excitatory connections among the six layers of the neocortex. However, excitatory neurons in layer 6 (L6), a layer whose functional organization is poorly understood, form relatively rare synaptic connections with other cortical excitatory neurons. Here, we show that the vast majority of parvalbumin inhibitory neurons in a sublamina within L6 send axons through the cortical layers toward the pia.

Synaptic Organization of the Neuronal Circuits of the Claustrum.

The claustrum, a poorly understood subcortical structure located between the cortex and the striatum, forms widespread connections with almost all cortical areas, but the cellular organization of claustral circuits remains largely unknown. Based primarily on anatomical data, it has been proposed that the claustrum integrates activity across sensory modalities. However, the extent to which the synaptic organization of claustral circuits supports this integration is unclear.

Behavioral and neural discrimination of speech sounds after moderate or intense noise exposure in rats.

Objectives: Hearing loss is a commonly experienced disability in a variety of populations including veterans and the elderly and can often cause significant impairment in the ability to understand spoken language. In this study, we tested the hypothesis that neural and behavioral responses to speech will be differentially impaired in an animal model after two forms of hearing loss.

Design: Sixteen female Sprague-Dawley rats were exposed to one of two types of broadband noise which was either moderate or intense.

Layer 6 corticothalamic neurons activate a cortical output layer, layer 5a.

Layer 6 corticothalamic neurons are thought to modulate incoming sensory information via their intracortical axons targeting the major thalamorecipient layer of the neocortex, layer 4, and via their long-range feedback projections to primary sensory thalamic nuclei. However, anatomical reconstructions of individual layer 6 corticothalamic (L6 CT) neurons include examples with axonal processes ramifying within layer 5, and the relative input of the overall population of L6 CT neurons to layers 4 and 5 is not well understood. We compared the synaptic impact of L6 CT cells on neurons in layers 4 and 5.

Neural mechanisms supporting robust discrimination of spectrally and temporally degraded speech.

Cochlear implants provide good speech discrimination ability despite highly limited amount of information they transmit compared with normal cochlea. Noise vocoded speech, simulating cochlear implants in normal hearing listeners, have demonstrated that spectrally and temporally degraded speech contains sufficient cues to provide accurate speech discrimination. We hypothesized that neural activity patterns generated in the primary auditory cortex by spectrally and temporally degraded speech sounds will account for the robust behavioral discrimination of speech.