Naturalizing Aesthetics

Aesthetic processing is about what we like and dislike. It applies to all types of perceived objects, not just art works. There should be a general brain network that deals with aesthetic appraisals of like and dislike regardless of the appraised object. In order to investigate this, the authors carried out a large-scale meta-analysis of published neuroimaging studies of aesthetic processing for objects that are perceived using four different sensory pathways: vision, audition, taste, and smell. A part of the brain called the anterior insula appeared as the most concordant area of activation across the four sensory pathways. From an evolutionary standpoint, it most likely that the appreciation of human artifacts like art works piggybacked onto an existing system for the appraisal of objects of biological importance, such as food sources and potential mates.

The science and engineering behind sensitized brain-controlled bionic hands

Advances in our understanding of brain function, along with the development of neural interfaces that allow for the monitoring and activation of neurons, have paved the way for brain machine interfaces (BMI), which harness neural signals to reanimate the limbs via electrical activation of the muscles, or to control extra-corporeal devices, thereby bypassing the muscles and senses altogether. BMIs consist of reading out motor intent from the neuronal responses monitored in motor regions of the brain and executing intended movements using bionic limbs, reanimated limbs, or exoskeletons. BMIs also allow for the restoration of the sense of touch by electrically activating neurons in somatosensory regions of the brain, thereby evoking vivid tactile sensations and conveying feedback about object interactions. In this review, we discuss the neural mechanisms of motor control and somatosensation in able-bodied individuals and describe approaches to use neuronal responses as control signals for movement restoration and to activate residual sensory pathways to restore touch. While the focus of the review is on intracortical approaches, we also describe alternative signal sources for control and non-invasive strategies for sensory restoration.

Contralateral and Ipsilateral Interactions in the Somatosensory Pathway in Healthy Humans

Hyper-adaptability, the ability to adapt to changes in the internal environment caused by neurological disorders, is necessary to recover from various disabilities, such as motor paralysis and sensory impairment. In the recovery from motor paralysis, the pre-existing neural pathway of the ipsilateral descending pathway, which is normally suppressed and preserved in the course of development, is activated to contribute to the motor control of the paretic limb. Conversely, in sensory pathways, it remains unclear whether there are compensatory pathways which are beneficial for the recovery of sensory impairment due to damaged unilateral somatosensory pathways, such as thalamic hemorrhage. Here, we investigated the interaction between the left and right somatosensory pathways in healthy humans using paired median nerve somatosensory evoked potentials (SEPs). Paired median nerve SEPs were recorded at CP3 and CP4 with a reference of Fz in the International 10–20 System. The paired median nerve stimulation with different interstimulus intervals (ISIs; 1, 2, 3, 5, 10, 20, 40, 60, and 100 ms) was performed to test the influence of the first stimulus (to the right median nerve) on the P14, P14/N20, and N20/P25 components induced by the second stimulus (left side). Results showed that the first stimulation had no effect on SEP amplitudes (P14, P14/N20, and N20/P25) evoked by the second stimulation in all ISI conditions, suggesting that there might not be a neural connectivity formed by a small number of synapses in the left–right interaction of the somatosensory pathway. Additionally, the somatosensory pathway may be less diverse in healthy participants.

Auditory input enhances somatosensory encoding and tactile goal-directed behavior

The capacity of the brain to encode multiple types of sensory input is key to survival. Yet, how neurons integrate information from multiple sensory pathways and to what extent this influences behavior is largely unknown. Using two-photon Ca2+ imaging, optogenetics and electrophysiology in vivo and in vitro, we report the influence of auditory input on sensory encoding in the somatosensory cortex and show its impact on goal-directed behavior. Monosynaptic input from the auditory cortex enhanced dendritic and somatic encoding of tactile stimulation in layer 2/3 (L2/3), but not layer 5 (L5), pyramidal neurons in forepaw somatosensory cortex (S1). During a tactile-based goal-directed task, auditory input increased dendritic activity and reduced reaction time, which was abolished by photoinhibition of auditory cortex projections to forepaw S1. Taken together, these results indicate that dendrites of L2/3 pyramidal neurons encode multisensory information, leading to enhanced neuronal output and reduced response latency during goal-directed behavior.

A REVIEW ON THE CONCEPT OF HRIDYA IN AYURVEDA: LOOKING BEYOND CARDIO TONICS

The term Hridya is used in different contexts with reference to different articles with diverse characteristics. Unlike the various Ayurvedic terms which can be more or less understood by the term itself, the term Hridya need a more elucidation. It is vital to screen these basic terms and find their meanings in different aspects for better discernment of Hridya in Ayurveda Hence this article attempts to illuminate the concept Hridya and the diversities in the Hridya dravyas mentioned in different contexts. On critical analysis of the literature and recent studies it can be understood that Ayurveda has included heart and brain in the umbrella term ‘Hridaya’. The Hridya dravyas can thus be understood as Cardiac or Central Nervous System (CNS) stimulants which evoke stimulation through various chemo-sensory pathways. Overall, commentaries describe Hridya as something pleasing or that which is good for the body. All the pleasurable sensations of the body attained by virtue of taste, smell, touch and by mere sight can be comprised under the concept Hridya and the act and articles which impart the pleasurable sensation can be understood as Hridya dravyas. As such the classical textbooks have references of food articles, flowers, fragrances, etc. described as Hridya dravyas as they have the ability impart the pleasurable sensation in common. While portraying the concept Hridya, the motor, sensory and psychological components should be taken contemplated. Any stimuli that impart a sense of pleasure to the respective sense organ and hence impart a sense of pleasure in Hridaya can be considered as Hridya.

Molecular and cellular basis of acid taste sensation in Drosophila

Acid taste, evoked mainly by protons (H+), is a core taste modality for many organisms. The hedonic valence of acid taste is bidirectional: animals prefer slightly but avoid highly acidic foods. However, how animals discriminate low from high acidity remains poorly understood. To explore the taste perception of acid, we use the fruit fly as a model organism. We find that flies employ two competing taste sensory pathways to detect low and high acidity, and the relative degree of activation of each determines either attractive or aversive responses. Moreover, we establish one member of the fly Otopetrin family, Otopetrin-like a (OtopLa), as a proton channel dedicated to the gustatory detection of acid. OtopLa defines a unique subset of gustatory receptor neurons and is selectively required for attractive rather than aversive taste responses. Loss of otopla causes flies to reject normally attractive low-acid foods. Therefore, the identification of OtopLa as a low-acid sensor firmly supports our competition model of acid taste sensation. Altogether, we have discovered a binary acid-sensing mechanism that may be evolutionarily conserved between insects and mammals.

Early functional connectivity in the developing sensorimotor network that is independent of sensory experience

Neonatal sensory experience shapes development of neural pathways carrying sensory information to the cortex. These pathways link to wider functional networks that coordinate activity of separate cortical regions, but it remains unknown when these broader networks emerge or how their maturation is influenced by sensory experience. By imaging activity across the cortex in neonatal mice, we have found unexpectedly early emergence of coordinated activity within a sensorimotor network that includes whisker-related somatosensory cortex and motor cortex. This network is spontaneously active but is not engaged by sensory stimulation, even though whisker deflection reliably drives cortical activity within barrel cortex. Acute silencing of the sensory periphery ablated spontaneous activity that was restricted to barrel cortex but spared this early sensorimotor network coactivity, suggesting that it is driven from elsewhere. Furthermore, perturbing sensory experience by whisker trimming did not impact emergence or early maturation of spontaneous activity in the sensorimotor network. As such, functional sensorimotor cortical networks develop early and, in contrast to development of ascending sensory pathways, their initial maturation is independent of sensory experience.

Unveiling the sensory and interneuronal pathways of the neuroendocrine connectome in Drosophila

Neuroendocrine systems in animals maintain organismal homeostasis and regulate stress response. Although a great deal of work has been done on the neuropeptides and hormones that are released and act on target organs in the periphery, the synaptic inputs onto these neuroendocrine outputs in the brain are less well understood. Here, we use the transmission electron microscopy reconstruction of a whole central nervous system in the Drosophila larva to elucidate the sensory pathways and the interneurons that provide synaptic input to the neurosecretory cells projecting to the endocrine organs. Predicted by network modeling, we also identify a new carbon dioxide-responsive network that acts on a specific set of neurosecretory cells and that includes those expressing corazonin (Crz) and diuretic hormone 44 (Dh44) neuropeptides. Our analysis reveals a neuronal network architecture for combinatorial action based on sensory and interneuronal pathways that converge onto distinct combinations of neuroendocrine outputs.