Brief Communications in 2009

Personality differences related to how equally people prefer to share rewards modulate amygdala activity, reports this fMRI study. This suggests that these personality differences are more likely to be due to automatic emotional processing.

Accurate taste perception relies on a properly functioning olfactory system. The authors demonstrate a reciprocal connection between taste and olfaction by showing that inactivation of the taste cortex also affects olfactory perception.

The shell subregion of nucleus LMAN is an output for the basal ganglia in song birds. The authors report that lesions of the this region do not immediately disrupt vocal behavior but do prevent the development of stable vocal sequences and the ability to imitate vocal sounds.

Visual resolution is best at the center of the retina, where the cones are packed together most closely, and decreases outside of this area, where cones are farther apart. Combining adaptive optics imaging and psychophysical testing, the authors reveal that resolution actually falls off much more quickly than cone spacing would predict.

Previous work has suggested that triggering transmitter release might require the opening of many Ca²⁺ channels. Here the authors show that at the inhibitory basket cell–granule cell synapse in rat hippocampus, the opening of three or fewer Ca²⁺ channels is sufficient to trigger transmitter release with high temporal precision.

In cultured rat hippocampal neurons, thrombospondin 1 hastened synapse formation via interaction with neuroligin 1.

This study finds that excitatory neurons in cortical layer 2/3 can respond to their own firing with persistent hyperpolarization, termed slow self-inhibition or SSI. This process is mediated by endocannabinoids and regulates neuronal excitability.

Cue-evoked activity of midbrain dopamine neurons is proposed to encode the magnitude, delay and uncertainty of predicted rewards. Here the authors report that this activity separates costs and benefits, as it does not encode the costs of the action required to obtain predicted rewards.

Dendritic excitability is a plastic property of neurons. This study shows that exposure to an enriched environment increases propagation of dendritic sodium spikes in a subset of dendritic branches in CA1 pyramidal neurons. This effect is mediated by localized downregulation of A-type potassium channel function.

Studying a patient with selective damage to the insular and anterior cingulate cortex, the current study finds that these regions are not necessary for interoceptive awareness of one's own heartbeat, but the primary somatosensory cortex is required for such self-awareness.

Although numerous in vivo studies have suggested that hippocampal theta oscillations are generated by the extrinsic medial septal input, theoretical studies have suggested that the hippocampus has the minimal feedback circuitry necessary to intrinsically generate its own theta rhythm. Here, Goutagny et al. directly demonstrate such oscillation independently of external inputs.

Contrary to previous findings, this study finds that ablation of microglia, the resident macrophages of the brain, does not affect amyloid plaque or neuritic pathology in two mouse models of Alzheimer's disease.

Although previous work has shown that extensive training in the complex visuo-motor skills involved in juggling results in adult gray-matter changes, it is unclear whether such practice can produce similar changes in adult white matter. This paper now uses diffusion tensor imaging to demonstrate structural white-matter changes when adults practice juggling.

Tonic pain, a chief clinical problem, is difficult to study in rodent models that measure threshold changes of evoked reactions to acutely applied stimuli. These authors used conditioned place preference to assess tonic pain in rats and measure the efficacy of agents that relieve it.

The instinctual attachment of young animals to their mothers is crucial for survival. Demonstrating the overriding importance of attachment, very young rat pups learn to prefer an odor coupled to electrical shock if the mother is present. This paper shows that low amygdalar dopamine signaling in very young pups is essential for their paradoxical response to odor/shock conditioning.

Sharp wave-ripple (SPW-R) complexes during sleep or rest have yet to be causally linked to memory consolidation. Here, the authors show that suppressing hippocampal SPW-Rs during post-training sleep in rats impairs the consolidation of a hippocampus-dependent spatial memory task.

This paper shows that synapses between CA1 pyramidal cells in the hippocampus and the tempero-ammonic pathway in the entorhinal cortex undergo spike timing-dependent plasticity.

The amygdala is thought to process fear-related stimuli rapidly and nonconsciously. Here, the authors report that an individual with complete lesion of the amygdala shows normal rapid detection and nonconscious processing of fearful faces, despite being unable to recognize fear from faces.

The amygdala is critical for processing information about emotion, but little is known about what role it might play in human behavioral interactions. Here the authors report that a patient with complete bilateral amydala lesions lacks any sense of personal space, and that in healthy controls the amygdala is activated by close personal proximity.

This study uses inducible ablation of NeuroD1 from adult neuronal stem cells/progenitors to show that this transcription factor is crucial for the survival and maturation of adult-born neurons in the hippocampus and olfactory bulb.