The basal ganglia and thalamus of the long-tailed macaque in stereotaxic coordinates. A template atlas based on coronal, sagittal and horizontal brain sections

A stereotaxic brain atlas of the basal ganglia and thalamus of Macaca fascicularis presented here is designed with a surgical perspective. In this regard, all coordinates have been referenced to a line linking the anterior and posterior commissures (ac–pc line) and considering the center of the ac at the midline as the origin of the bicommissural space. The atlas comprises of 43 different plates (19 coronal levels, 10 sagittal levels and 14 horizontal levels). In addition to ‘classical’ cyto- and chemoarchitectural techniques such as the Nissl method and the acetylcholinesterase stain, several immunohistochemical stains have been performed in adjacent sections, including the detection of tyrosine hydroxylase, enkephalin, neurofilaments, parvalbumin and calbindin. In comparison to other existing stereotaxic atlases for M. fasicularis, this atlas has two main advantages: firstly, brain cartography is based on a wide variety of cyto- and chemoarchitectural stains carried out on adjacent sections, therefore enabling accurate segmentation. Secondly and most importantly, sagittal and horizontal planes are included. Sagittal planes are very useful for calculating oblique trajectories, whereas, clinical researchers engaged in neuroimaging studies will be more familiar with horizontal sections, as they use horizontal (also called “axial”) brain images in their daily routine of their clinical practices

Insights on the Neuromagnetic Representation of Temporal Asymmetry in Human Auditory Cortex.

Communication sounds are typically asymmetric in time and human listeners are highly sensitive to this short-term temporal asymmetry. Nevertheless, causal neurophysiological correlates of auditory perceptual asymmetry remain largely elusive to our current analyses and models. Auditory modelling and animal electrophysiological recordings suggest that perceptual asymmetry results from the presence of multiple time scales of temporal integration, central to the auditory periphery. To test this hypothesis we recorded auditory evoked fields (AEF) elicited by asymmetric sounds in humans. We found a strong correlation between perceived tonal salience of ramped and damped sinusoids and the AEFs, as quantified by the amplitude of the N100m dynamics. The N100m amplitude increased with stimulus half-life time, showing a maximum difference between the ramped and damped stimulus for a modulation half-life time of 4 ms which is greatly reduced at 0.5 ms and 32 ms. This behaviour of the N100m closely parallels psychophysical data in a manner that: i) longer half-life times are associated with a stronger tonal percept, and ii) perceptual differences between damped and ramped are maximal at 4 ms half-life time. Interestingly, differences in evoked fields were significantly stronger in the right hemisphere, indicating some degree of hemispheric specialisation. Furthermore, the N100m magnitude was successfully explained by a pitch perception model using multiple scales of temporal integration of auditory nerve activity patterns. This striking correlation between AEFs, perception, and model predictions suggests that the physiological mechanisms involved in the processing of pitch evoked by temporal asymmetric sounds are reflected in the N100m

Distinct brain representations of processed and unprocessed foods

Among all of the stimuli surrounding us, food is arguably the most rewarding for the essential role it plays in our survival. In previous visual recognition research, it has already been demonstrated that the brain not only differentiates edible stimuli from non-edible stimuli but also is endowed with the ability to detect foods\u2019 idiosyncratic properties such as energy content. Given the contribution of the cooked diet to human evolution, in the present study we investigated whether the brain is sensitive to the level of processing food underwent, based solely on its visual appearance. We thus recorded visual evoked potentials (VEPs) from normal-weight healthy volunteers who viewed color images of unprocessed and processed foods equated in caloric content. Results showed that VEPs and underlying neural sources differed as early as 130 ms post-image onset when participants viewed unprocessed versus processed foods, suggesting a within-category early discrimination of food stimuli. Responses to unprocessed foods engaged the inferior frontal and temporal regions and the premotor cortices. In contrast, viewing processed foods led to the recruitment of occipito-temporal cortices bilaterally, consistently with other motivationally relevant stimuli. This is the first evidence of diverging brain responses to food as a function of the transformation undergone during its preparation that provides insights on the spatiotemporal dynamics of food recognition

Baseline Vagal Tone Predicts BOLD Response during Elicitation of Grief

Previous studies of the relationship between autonomic and central nervous system activity using fMRI have primarily utilized cognitive, motor or conditioning tasks. The present study investigated the association between the regional brain activity during the evocation of grief and baseline parasympathetic activity. Eight right-handed women who had experienced the death of a loved one in the past 18 months were scanned during the presentation of personalized pictures and words that evoked grief and had a measure of baseline parasympathetic activity taken. Greater posterior cingulate cortex (PCC) activity was associated with lower parasympathetic activity (eg more arousal). Connectivity has been demonstrated between the ventral PCC (vPCC) and the subgenual ACC (sACC), which then projects to the autonomic nuclei. In the present study, functional connectivity analysis revealed a positive correlation between vPCC and sACC/orbitofrontal cortical activity. Additionally, bilateral cuneus and parahippocampus were associated with higher baseline parasympathetic tone, important to visual perception in emotional processing and episodic memory respectively. Future studies should compare differences between central and peripheral arousal in complicated and non-complicated grief