Emotion perception bias associated with the hijab in Austrian and Turkish participants.

In a cross-cultural study, we investigated the link between explicit attitudes towards the hijab and implicit measures of cultural and religious bias during the recognition of emotions. Participants tested in Austria (N = 71) and in Turkey (N = 70) reported their attitude towards the hijab, and categorised in a mousetracker task happy and sad faces of women, shown with five levels of intensity, and framed either by a hijab or by an oval-shaped mask. The two samples did not differ in their explicit attitudes towards the hijab. However, negative attitude towards the hijab predicted greater sadness attribution to happy faces with the hijab in Austrian participants. Unrelated to their explicit attitudes, Turkish participants attributed more sadness to happy faces with than without the hijab. Results suggest that the sight of the hijab activated, in both Austrian and Turkish participants, implicit biases resulting in associations with sadness and negative emotions.

Low-threshold spiking interneurons perform feedback inhibition in the lateral amygdala.

Amygdala plays crucial roles in emotional learning. The lateral amygdala (LA) is the input station of the amygdala, where learning related plasticity occurs. The LA is cortical like in nature in terms of its cellular make up, composed of a majority of principal cells and a minority of interneurons with distinct subtypes defined by morphology, intrinsic electrophysiological properties and neurochemical expression profile. The specific functions served by LA interneuron subtypes remain elusive. This study aimed to elucidate the interneuron subtype mediating feedback inhibition. Electrophysiological evidence involving antidromic activation of recurrent LA circuitry via basolateral amygdala stimulation and paired recordings implicate low-threshold spiking interneurons in feedback inhibition. Recordings in somatostatin-cre animals crossed with tdtomato mice have revealed remarkable similarities between a subset of SOM+ interneurons and LTS interneurons. This study concludes that LTS interneurons, most of which are putatively SOM+, mediate feedback inhibition in the LA. Parallels with cortical areas and potential implications for information processing and plasticity are discussed.

Anatomical and electrophysiological changes in striatal TH interneurons after loss of the nigrostriatal dopaminergic pathway.

Using transgenic mice that express enhanced green fluorescent protein (EGFP) under the control of the tyrosine hydroxylase (TH) promoter, we have previously shown that there are approximately 3,000 striatal EGFP-TH interneurons per hemisphere in mice. Here, we report that striatal TH-EGFP interneurons exhibit a small, transient but significant increase in number after unilateral destruction of the nigrostriatal dopaminergic pathway. The increase in cell number is accompanied by electrophysiological and morphological changes. The intrinsic electrophysiological properties of EGFP-TH interneurons ipsilateral to 6-OHDA lesion were similar to those originally reported in intact mice except for a significant reduction in the duration of a characteristic depolarization induced plateau potential. There was a significant change in the distribution of the four previously described electrophysiologically distinct subtypes of striatal TH interneurons. There was a concomitant increase in the frequency of both spontaneous excitatory and inhibitory post-synaptic currents, while their amplitudes did not change. Nigrostriatal lesions did not affect somatic size or dendritic length or branching, but resulted in an increase in the density of proximal dendritic spines and spine-like appendages in EGFP-TH interneurons. The changes indicate that electrophysiology properties and morphology of striatal EGFP-TH interneurons depend on endogenous levels of dopamine arising from the nigrostriatal pathway. Furthermore, these changes may serve to help compensate for the changes in activity of spiny projection neurons that occur following loss of the nigrostriatal innervation in experimental or in early idiopathic Parkinson's disease by increasing feedforward GABAergic inhibition exerted by these interneurons.

A novel functionally distinct subtype of striatal neuropeptide Y interneuron.

We investigated the properties of neostriatal neuropeptide Y (NPY)-expressing interneurons in transgenic GFP (green fluorescent protein)-NPY reporter mice. In vitro whole-cell recordings and biocytin staining demonstrated the existence of a novel class of neostriatal NPY-expressing GABAergic interneurons that exhibit electrophysiological, neurochemical, and morphological properties strikingly different from those of previously described NPY-containing, plateau-depolarization low-threshold spike (NPY-PLTS) interneurons. The novel NPY interneuron type (NPY-neurogliaform) differed from previously described NPY-PLTS interneurons by exhibiting a significantly lower input resistance and hyperpolarized membrane potential, regular, nonaccommodating spiking in response to depolarizing current injections, and an absence of plateau depolarizations or low-threshold spikes. NPY-neurogliaform interneurons were also easily distinguished morphologically by their dense, compact, and highly branched dendritic and local axonal arborizations that contrasted sharply with the sparse and extended axonal and dendritic arborizations of NPY-PLTS interneurons. Furthermore, NPY-neurogliaform interneurons did not express immunofluorescence for somatostatin or nitric oxide synthase that was ubiquitous in NPY-PLTS interneurons. IPSP/Cs could only rarely be elicited in spiny projection neurons (SPNs) in paired recordings with NPY-PLTS interneurons. In contrast, the probability of SPN innervation by NPY-neurogliaform interneurons was extremely high, the synapse very reliable (no failures were observed), and the resulting postsynaptic response was a slow, GABA(A) receptor-mediated IPSC that has not been previously described in striatum but that has been elicited from NPY-GABAergic neurogliaform interneurons in cortex and hippocampus. These properties suggest unique and distinctive roles for NPY-PLTS and NPY-neurogliaform interneurons in the integrative properties of the neostriatum.

Distribution of tyrosine hydroxylase-expressing interneurons with respect to anatomical organization of the neostriatum.

We have recently shown in vitro that striatal tyrosine hydroxylase-expressing interneurons identified in transgenic mice by expression of enhanced green fluorescent protein (TH-eGFP) display electrophysiological profiles that are distinct from those of other striatal interneurons. Furthermore, striatal TH-eGFP interneurons show marked diversity in their electrophysiological properties and have been divided into four distinct subtypes. One question that arises from these observations is whether striatal TH-eGFP interneurons are distributed randomly, or obey some sort of organizational plan as has been shown to be the case with other striatal interneurons. An understanding of the striatal TH-eGFP interneuronal patterning is a vital step in understanding the role of these neurons in striatal functioning. Therefore, in the present set of studies the location of electrophysiologically identified striatal TH-eGFP interneurons was mapped. In addition, the distribution of TH-eGFP interneurons with respect to the striatal striosome-matrix compartmental organization was determined using µ-opioid receptor (MOR) immunofluorescence or intrinsic TH-eGFP fluorescence to delineate striosome and matrix compartments. Overall, the distribution of the different TH-eGFP interneuronal subtypes did not differ in dorsal versus ventral striatum. However, striatal TH-eGFP interneurons were found to be mostly in the matrix in the dorsal striatum whereas a significantly higher proportion of these neurons was located in MOR-enriched domains of the ventral striatum. Further, the majority of striatal TH-eGFP interneurons was found to be located within 100 µm of a striosome-matrix boundary. Taken together, the current results suggest that TH-eGFP interneurons obey different organizational principles in dorsal versus ventral striatum, and may play a role in communication between striatal striosome and matrix compartments.

Electrophysiological and morphological characteristics and synaptic connectivity of tyrosine hydroxylase-expressing neurons in adult mouse striatum.

Whole-cell recordings were obtained from tyrosine hydroxylase-expressing (TH(+)) neurons in striatal slices from bacterial artificial chromosome transgenic mice that synthesize enhanced green fluorescent protein (EGFP) selectively in neurons expressing TH transcriptional regulatory sequences. Stereological cell counting indicated that there were approximately 2700 EGFP-TH(+) neurons/striatum. Whole-cell recordings in striatal slices demonstrated that EGFP-TH(+) neurons comprise four electrophysiologically distinct neuron types whose electrophysiological properties have not been reported previously in striatum. EGFP-TH(+) neurons were identified in retrograde tracing studies as interneurons. Recordings from synaptically connected pairs of EGFP-TH(+) interneurons and spiny neurons showed that the interneurons elicited GABAergic IPSPs/IPSCs in spiny neurons powerful enough to significantly delay evoked spiking. EGFP-TH(+) interneurons responded to local or cortical stimulation with glutamatergic EPSPs. Local stimulation also elicited GABA(A) IPSPs, at least some of which arose from identified spiny neurons. Single-cell reverse transcription-PCR showed expression of VMAT1 in EGFP-TH(+) interneurons, consistent with previous suggestions that these interneurons may be dopaminergic as well as GABAergic. All four classes of interneurons were medium sized with modestly branching, varicose dendrites, and dense, highly varicose axon collateral fields. These data show for the first time that there exists in the normal rodent striatum a substantial population of TH(+)/GABAergic interneurons comprising four electrophysiologically distinct subtypes whose electrophysiological properties differ significantly from those of previously described striatal GABAergic interneurons. These interneurons are likely to play an important role in striatal function through fast GABAergic synaptic transmission in addition to, and independent of, their potential role in compensation for dopamine loss in experimental or idiopathic Parkinson's disease.