Differential mastication kinematics of the rabbit in response to food and water: Implications for conditioned movement

Analysis of naturalistic chewing patterns may provide insight into mapping the neural substrates of jaw movement control systems, including their adaptive modification during the classically conditioned jaw movement (CJM) paradigm. Here, New Zealand White rabbits were administered food and water stimuli orally to evaluate the influence of stimulus consistency on masticatory pattern. Chewing patterns were recorded via video camera and movements were analyzed by computerized image analysis. The mandibular kinematics, specifically the extent of dorsal/ventral, medial/lateral, and rostral/caudal movement, were significantly larger in food-evoked than water-evoked chewing. Water-evoked chewing frequency, however, was significantly higher than that of food-evoked movements. In light of known cortical mastication modulatory centers, our findings implicate different neural substrates for the responses to food and water stimuli in the rabbit. A detailed delineation of jaw movement patterns and circuitry is essential to characterize the neural substrates of CJM.     

A quantitative near-infrared spectroscopy study: a decrease in cerebral hemoglobin oxygenation in Alzheimer's disease and mild cognitive impairment

A newly developed quantitative near-infrared spectroscopy (NIRS) system was used to measure changes in cortical hemoglobin oxygenation during the Verbal Fluency Task in 32 healthy controls, 15 subjects with mild cognitive impairment (MCI), and 15 patients with Alzheimer's disease (AD). The amplitude of changes in the waveform, which was quantitatively calculated by a signal processing method, was significantly lower in the frontal, and the bilateral parietal areas in the AD group, whereas that in the MCI group was significantly lower only in the right parietal area. The NIRS system may be a potential tool for the primary screening of AD.     

Differential Mastication Kinematics of the Rabbit in Response to Food and Water: Implications for Conditioned Movement

Analysis of naturalistic chewing patterns may provide insight into mapping the neural substrates of jaw movement control systems, including their adaptive modification during the classically conditioned jaw movement (CJM) paradigm. Here, New Zealand White rabbits were administered food and water stimuli orally to evaluate the influence of stimulus consistency on masticatory pattern. Chewing patterns were recorded via video camera and movements were analyzed by computerized image analysis. The mandibular kinematics, specifically the extent of dorsal/ventral, medial/lateral, and rostral/caudal movement, were significantly larger in food-evoked than water-evoked chewing. Water-evoked chewing frequency, however, was significantly higher than that of food-evoked movements. In light of known cortical mastication modulatory centers, our findings implicate different neural substrates for the responses to food and water stimuli in the rabbit. A detailed delineation of jaw movement patterns and circuitry is essential to characterize the neural substrates of CJM.     

Modulations of muscle modes in automatic postural responses induced by external surface translations

The authors applied principal component analysis to investigate muscle activation patterns (M-modes) involved in the automatic postural responses induced by external surface perturbations. They focused on M-mode modulations as responses to the effects of practice, stability of the conditions and perturbed directions. While peak center of mass velocity reduced with practice, M-modes were similar with practice and across stability conditions. In contrast, atypical sway mode coactivations that combined proximal trunk muscles with distal muscles of the opposite lower extremity of the ventral-dorsal side were observed under the unstable conditions in both forward and backward perturbations after practice. In addition, M-modes in the forward translations were characterized by increased cocontraction patterns. Results suggest that compositions of the underlying M-modes show minor differences in each perturbed direction, but practice enhances coactivation patterns combining proximal muscles with distal muscles, and with accompanying cocontraction patterns, under more challenging conditions.     

Mediating effect of environmental rewards on the relation between goal-directed behaviour and anhedonia

Depression can be explained by certain behavioural patterns, especially low levels of environmental rewards; it is generally accompanied by infrequent goal-directed behaviour, increased depressed mood, and anhedonia. However, no research has statistically examined the mediating effect of environmental rewards on the relation between goal-directed behaviour and the symptoms of depressed mood or anhedonia. This study sought to determine whether such a mediating effect of environmental rewards is present in cross-sectional study. The participants included 101 patients diagnosed with major depressive disorders. Data were collected through three questionnaires measuring depression and behavioural patterns that maintain depression: the Center for Epidemiologic Studies Depression Scale (CES-D), the Environmental Reward Observation Scale (EROS), and the Behavioral Activation for Depression Scale—Short Form (BADS-SF). Mediation analysis was conducted using depressed mood and anhedonia as dependent variables, environmental rewards as the mediating variable, and goal-directed behaviour as the independent variable. Environmental rewards significantly mediated the relationship between goal-directed behaviour and anhedonia but not that between goal-directed behaviour and depressed mood. No significant relationships were found among depressed mood, goal-directed behaviour and environmental rewards. From these results, we conclude that low levels of environmental rewards accompanied by infrequent goal-directed behaviour can lead to increased anhedonia but not depressed mood.