The role of the amygdala in processing social and affective touch

The amygdala plays a central role in socio-emotional behavior, yet its role in processing affective touch is not well established. Longitudinal studies reveal that touch-deprived infants show later in life exaggerated emotional reactivity related to structural and functional changes in the amygdala. The connectivity of the amygdala is well-suited to process the sensory features and the socio-cognitive dimensions of touch. The convergent processing of bottom-up and top-down touch-related inputs in the amygdala triggers autonomic responses. The positive hedonic value of touch in humans and grooming in non-human primates is correlated with vagal tone and the release of oxytocin and endogenous opioids. Grooming reduces vigilance that has been shown to depend critically on the amygdala. Touch-induced vagal tone and lowered vigilance alter neural activity in the amygdala. Under these circumstances neurons no longer respond to each touch stimulus, rather they appear to signal a sustained functional state in which the amygdala appears decoupled from monitoring the external environment.

TINGKAT PENGETAHUAN PERAWAT DALAM MELAKUKAN MASSAGE PADA BAYI BARU LAHIR DI RUMAH SAKIT ADVENT BANDUNG

Latar Belakang: Massage bayi merupakan seni perawatan kesehatan dan pengobatan yang dipraktikkan sejak berabad-abad, Massage bayi disebut dengan stimulus touch dan dapat diberikan sedini mungkin kepada bayi baru lahir, massage bayi ini sangat banyak manfaatnya yaitu dapat meningkatkan berat badan pada bayi, memberikan kenyaman kepada bayi, membantu melancarkan sirkulasi darah pada bayi, membantu melancarka sistem percernaan pada bayi. Penelitian ini bertujuan mengetahui tingkat pengetahuan perawat dalam melakukan massage pada bayi baru lahir. Penelitian merupakan hasil analisis corelational dengan rancangan cross sectional yang dilakukan dengan membagikan kuesioner. Responden merupakan karyawan Rumah Sakit Advent Bandung di departemen Obgyn. Hasil penelitian menunjukkan pengetahuan perawat tentang pijat bayi berpengetahuan baik (20,3%) Uji statistik Chi square menunjukkan 0,000)<α0,05 yang artinya ada hubungan antara pengetahuan perawat tentang pijat bayi di Rumah Sakit Advent Bandung. Background: Baby massage is an art of health care and medicine that has been practiced for centuries, baby massage is called the touch stimulus and can be given as early as possible to newborns, this baby massage has many benefits, namely it can increase weight in babies, provide comfort. to babies, helps improve blood circulation in babies, helps smooth the digestive system in babies. This study aims to determine the level of knowledge of nurses in performing massage for newborns. This study is the result of a correlational analysis with a cross-sectional design which was conducted by distributing questionnaires. Respondents are employees of the Bandung Adventist Hospital in the Obgyn department. The results showed that the knowledge of nurses about infant massage had good knowledge (20.3%). Chi square statistical test showed 0.000) <α0.05, which means that there is a relationship between the knowledge of nurses about infant massage at Adventist Hospital Bandung.

Chemosensitivity and role of swimming legs of mud crab, Scylla paramamosain, in feeding activity as determined by electrocardiographic and behavioural observations

Swimming crabs have a characteristic fifth pair of legs that are flattened into paddles for swimming purposes. The dactyl of these legs bears a thick seta along its edge. The chemoreceptive and feeding properties of the seta are supported with scientific evidence; however, there is no available data on the sensitivity of the setae in portunid crabs. The underlying mechanisms of the chemo- and mechano-sensitivity of appendages and their involvement in feeding activities of the mud crab (Scylla paramamosain) were investigated using electrocardiography and behavioural assay, which focused on the responses of the mud crab to chemical and touch stimulus. Electrocardiography revealed the sensory properties of the appendages. The dactyls of swimming legs and the antennules were chemosensitive, but not mechanosensitive and vice versa for the antennae. However, the mouthparts, claws, and walking legs were chemo- and mechanosensitive. Only the chemosensitive appendages, including the swimming legs, were directly involved in feeding. The flattened dactyls of the swimming legs were more efficient than the pointed dactyls of the walking legs in detecting the food organism crawling on the substrate. The structural features enhanced the capacity of the crab in coming into contact with scattered food items. This study revealed that the swimming legs are important appendages for feeding in the mud crab.

Kinematics Governing Mechanotransduction in the Sensory Hair of the Venus flytrap

Insects fall prey to the Venus flytrap (Dionaea muscipula) when they touch the sensory hairs located on the flytrap lobes, causing sudden trap closure. The mechanical stimulus imparted by the touch produces an electrical response in the sensory cells of the trigger hair. These cells are found in a constriction near the hair base, where a notch appears around the hair’s periphery. There are mechanosensitive ion channels (MSCs) in the sensory cells that open due to a change in membrane tension; however, the kinematics behind this process is unclear. In this study, we investigate how the stimulus acts on the sensory cells by building a multi-scale hair model, using morphometric data obtained from μ-CT scans. We simulated a single-touch stimulus and evaluated the resulting cell wall stretch. Interestingly, the model showed that high stretch values are diverted away from the notch periphery and, instead, localized in the interior regions of the cell wall. We repeated our simulations for different cell shape variants to elucidate how the morphology influences the location of these high-stretch regions. Our results suggest that there is likely a higher mechanotransduction activity in these ’hotspots’, which may provide new insights into the arrangement and functioning of MSCs in the flytrap.

Mechanical touch responses of Arabidopsis TCH1-3 mutant roots on inclined hard-agar surface

The gravity-induced mechanical touch stimulus can affect plant root architecture. Mechanical touch responses of plant roots are an important aspect of plant root growth and development. Previous studies have reported that Arabidopsis TCH1-3 genes are involved in mechano-related events, how-ever, the physiological functions of TCH1-3 genes in Arabidopsis root mechanoresponses remain unclear. In the present study, we applied an inclined hard agar plate method to produce mechanical touch stimulus, and provided evidence that altered mechanical environment could influence root growth. Furthermore, tch1-3 Arabidopsis mutants were investigated on inclined agar surfaces to explore the functions of TCH1-3 genes on Arabidopsis root mechanoresponses. The results showed that two tch2 mutants, cml24-2 and cml24-4, exhibited significantly reduced root length, biased skewing, and decreased density of lateral root. In addition, primary root length and density of lateral root of tch3 (cml12-2) was significantly decreased on inclined agar surfaces. This study indicates that the tch2 and tch3 mutants are hypersensitive to mechanical touch stimulus, and TCH2 (CML24-2 and CML24-4) and TCH3 (CML12-2) genes may participate in the mechanical touch response of Arabidopsis roots.

Selective Expression of Electrical Correlates of Differential Appetitive Classical Conditioning in a Feeding Network

Electrical correlates of differential appetitive classical conditioning were recorded in the neural network that underlies feeding in the snail Lymnaea stagnalis. In spaced training (15 trials over 3 days), the lips and the tentacle were used as CS+ (reinforced conditioned stimulus) or CS− (nonreinforced conditioned stimulus) sites for behavioral tactile conditioning. In one group of experimental animals, touch to the lips (the CS+ site) was followed by sucrose (the unconditioned stimulus, US), but touch to the tentacle (the CS− site) was not reinforced. In a second experimental group the CS+/CS− sites were reversed. Semi-intact lip-tentacle-CNS preparations were made from both experimental groups and a naive control group. Intracellular recordings were made from the B3 motor neuron of the feeding network, which allowed the monitoring of activity in the feeding central pattern generator (CPG) interneurons as well as early synaptic inputs evoked by the touch stimulus. Following successful behavioral conditioning, the touch stimulus evoked CPG-driven fictive feeding activity at the CS+ but not the CS− sites in both experimental groups. Naive snails/preparations showed no touch responses. A weak asymmetrical stimulus generalization of conditioned feeding was not retained at the electrophysiological level. An early excitatory postsynaptic potential (EPSP) response to touch was only enhanced following conditioning in the Lip CS+/tentacle CS− group but not in the Tentacle CS+/lip CS− group. The results show that the main features of differential appetitive classical conditioning can be recorded at the electrophysiological level, but some characteristics of the conditioned response are selectively expressed in the reduced preparation.

Representation of Touch Location by a Population of Leech Sensory Neurons

Lewis, John E. and William B. Kristan, Jr. Representation of touch location by a population of leech sensory neurons. J. Neurophysiol. 80: 2584–2592, 1998. To form accurate representations of the world, sensory systems must accurately encode stimuli in the spike trains of populations of neurons. The nature of such neuronal population codes is beginning to be understood. We characterize the entire sensory system underlying a simple withdrawal reflex in the leech, a bend directed away from the site of a light touch. Our studies show that two different populations of mechanosensory neurons each encode touch information with an accuracy that can more than account for the behavioral output. However, we found that only one of the populations, the P cells, is important for the behavior. The sensory representation of touch location is based on the spike counts in all of the four P cells. Further, fewer than three action potentials in the P cell population, occurring during the first 100 ms of a touch stimulus, may be required to process touch location information to produce the appropriately directed bend.

Tomatoes Remember being Brushed

Tomato seedlings grown in close proximity elongate rapidly in a shade-avoidance response. A daily touch stimulus can eliminate the extra growth associated with shade avoidance. Experiments to determine how the touch stimulus is integrated were performed on tomato seedlings grown in plug trays 22 mm apart, starting when two fully expanded leaves overlapped between plants to induce the shade-avoidance response. The standard touch stimulus was applied by brushing the surface of the canopy 10 times each morning with a piece of Styrofoam sheet. This treatment reduced the daily growth rate from 7.7 to 5.8 mm/day, but quadrupling the dose further reduced growth only slightly (J. Amer. Soc. Hort. Sci. 121:894). The ability of the plants to sum individual stimuli was tested by varying the interval between the individual strokes. Intervals of 0.01, 0.1, 1 and 10 min all produced the same growth response. Thus, the individual strokes were perceived as a single stimulus. Had they been perceived as separate stimuli, long intervals would have increased the response. There was no refractory period of insensitivity following the stimulus; that would have reduced the response at longer intervals. The height reduction was directly proportional to the number of days that the treatment was applied, indicating that each day of treatment reduced the growth rate for only 1 day (from 5.9 mm/day to 2.7 mm/day). Thus, brief stimuli are integrated during the day and expressed as a reduction of growth the next diurnal cycle.

Touch sensitivity in oligochaete giant fibers is transiently enhanced by a single spike

Weak tactile stimulation of posterior segments in the freshwater oligochaete Lumbriculus variegatus evokes a single lateral giant fiber (LGF) spike but no overt escape shortening. After initiation of a single spike, giant-fiber excitability is increased, as reflected by a period of enhanced conduction velocity for a second LGF spike that follows 5–50 ms after the first. Using non-invasive recordings from intact worms and a biofeedback arrangement for stimulus delivery, it was shown that the period of enhanced velocity is associated with a marked increase in sensitivity to a second touch stimulus. Enhanced touch sensitivity is distributed within the LGF sensory field to loci remote from the original site of stimulation, leading to an increased likelihood that a second, weak stimulus will elicit rapid escape withdrawal.