How auditory neurons count temporal intervals and decode information.

The numerical sense of animals includes identifying the numerosity of a sequence of events that occur with specific intervals, e.g., notes in a call or bar of music.

Angular Head Velocity Cells within Brainstem Nuclei Projecting to the Head Direction Circuit.

The sense of orientation of an animal is derived from the head direction (HD) system found in several limbic structures and depends on an intact vestibular labyrinth. However, how the vestibular system influences the generation and updating of the HD signal remains poorly understood. Anatomical and lesion studies point toward three key brainstem nuclei as key components for generating the HD signal-nucleus prepositus hypoglossi, supragenual nucleus, and dorsal paragigantocellularis reticular nuclei.

Angular head velocity cells within brainstem nuclei projecting to the head direction circuit.

Unlabelled: An animal's perceived sense of orientation depends upon the head direction (HD) system found in several limbic structures and depends upon an intact peripheral vestibular labyrinth. However, how the vestibular system influences the generation, maintenance, and updating of the HD signal remains poorly understood. Anatomical and lesion studies point towards three key brainstem nuclei as being potential critical components in generating the HD signal: nucleus prepositus hypoglossi (NPH), supragenual nucleus (SGN), and dorsal paragigantocellularis reticular nuclei (PGRNd).

Landmark-modulated directional coding in postrhinal cortex.

Visual landmarks can anchor an animal's internal sense of orientation to the external world. The rodent postrhinal cortex (POR) may facilitate this processing. Here, we demonstrate that, in contrast to classic head direction (HD) cells, which have a single preferred orientation, POR HD cells develop a second preferred orientation when an established landmark cue is duplicated along another environmental wall.

High-Frequency Stimulation of Ventral CA1 Neurons Reduces Amygdala Activity and Inhibits Fear.

The hippocampus can be divided into distinct segments that make unique contributions to learning and memory. The dorsal segment supports cognitive processes like spatial learning and navigation while the ventral hippocampus regulates emotional behaviors related to fear, anxiety and reward. In the current study, we determined how pyramidal cells in ventral CA1 respond to spatial cues and aversive stimulation during a context fear conditioning task.

How auditory selectivity for sound timing arises: The diverse roles of GABAergic inhibition in shaping the excitation to interval-selective midbrain neurons.

Across sensory systems, temporal frequency information is progressively transformed along ascending central pathways. Despite considerable effort to elucidate the mechanistic basis of these transformations, they remain poorly understood. Here we used a novel constellation of approaches, including whole-cell recordings and focal pharmacological manipulation, in vivo, and new computational algorithms that identify conductances resulting from excitation, inhibition and active membrane properties, to elucidate the mechanisms underlying the selectivity of midbrain auditory neurons for long temporal intervals.

Phasic, suprathreshold excitation and sustained inhibition underlie neuronal selectivity for short-duration sounds.

Sound duration is important in acoustic communication, including speech recognition in humans. Although duration-selective auditory neurons have been found, the underlying mechanisms are unclear. To investigate these mechanisms we combined in vivo whole-cell patch recordings from midbrain neurons, extraction of excitatory and inhibitory conductances, and focal pharmacological manipulations.

Species specificity of temporal processing in the auditory midbrain of gray treefrogs: long-interval neurons.

In recently diverged gray treefrogs (Hyla chrysoscelis and H. versicolor), advertisement calls that differ primarily in pulse shape and pulse rate act as an important premating isolation mechanism. Temporally selective neurons in the anuran inferior colliculus may contribute to selective behavioral responses to these calls.

Species-specificity of temporal processing in the auditory midbrain of gray treefrogs: interval-counting neurons.

Interval-counting neurons (ICNs) respond after a threshold number of sound pulses have occurred with specific intervals; a single aberrant interval can reset the counting process. Female gray treefrogs, Hyla chrysoscelis and H. versicolor, discriminate against synthetic 'calls' possessing a single interpulse interval 2-3 three times the optimal value, suggesting that ICNs are important for call recognition.

Cortical representations are reinstated by the hippocampus during memory retrieval.

The hippocampus is assumed to retrieve memory by reinstating patterns of cortical activity that were observed during learning. To test this idea, we monitored the activity of individual cortical neurons while simultaneously inactivating the hippocampus. Neurons that were active during context fear conditioning were tagged with the long-lasting fluorescent protein H2B-GFP and the light-activated proton pump ArchT.

Combining pharmacology and whole-cell patch recording from CNS neurons, in vivo.

Whole-cell patch neurophysiology and pharmacological manipulations have provided unprecedented insight into the functions of central neurons, but their combined use has been largely restricted to in vitro preparations. We describe a method for performing whole-cell patch recording and focal application of pharmacological agents in vivo. A key feature of this technique involves iontophoresis of glutamate to establish proximity of drug and recording pipettes.