Behavioural brain research
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Autism is a severe neurodevelopmental disorder with a population prevalence of 1 in 68, and dramatically increasing. While no single pharmacologic intervention has successfully targeted the core symptoms of autism, emerging evidence suggests that postnatal environmental manipulations may offer greater therapeutic efficacy. Massage therapy, or tactile stimulation (TS), early in life has repeatedly been shown to be an effective, low-cost, therapeutic approach in ameliorating the cognitive, social, and emotional symptoms of autism. ⋯ The TS VPA animals, when compared to VPA animals, did not exhibit altered or improved behavior in the delayed non-match-to-sample T-maze, Whishaw tray reaching, activity box, or elevated plus maze tasks. Anatomically, however, there were significant increases in dendritic branching and spine density in the medial prefrontal cortex, orbital frontal cortex, and amygdala in VPA animals following early TS treatment, suggesting a complete reversal or remediation of the VPA-induced effects in these regions. The results suggest that postnatal TS, during a critical period in development, acts as a powerful reorganization tool that can ameliorate the neuroanatomical consequences of prenatal VPA exposure.
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Attention deficit hyperactivity disorder (ADHD) overdiagnosis and a pharmacological attempt to increase cognitive performance, are the major causes for the frequent (ab)use of psychostimulants in non-ADHD individuals. Methylphenidate is a non-addictive psychostimulant, although its mode of action resembles that of cocaine, a well-known addictive and abused drug. Neuronal- and glial-derived growth factors play a major role in the development, maintenance and survival of neurons in the central nervous system. ⋯ Neither treatments affected the behavioral parameters, although acute cocaine administration was associated with increased locomotor activity. It is possible that the increased hippocampal GDNF mRNA levels, may be relevant to the reduced rate of drug seeking behavior in ADHD adolescence that were maintained from childhood on methylphenidate. BDNF protein level increase with age, as well as following stimulant treatments at early age may be relevant to the neurobiology and pharmacotherapy of ADHD.
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Amygdala is involved in processing of primary emotions and particularly its central nucleus (CeA) also in pain control. Here we studied mechanisms mediating the descending control of mechanical hypersensitivity by the CeA in rats with a peripheral neuropathy in the left hind limb. For drug administrations, the animals had a guide cannula in the right CeA and an intrathecal catheter or another guide cannula in the medullary raphe. ⋯ The results indicate that depending on the dose, glutamate in the CeA has a descending facilitatory or inhibitory effect on neuropathic pain hypersensitivity. Serotoninergic raphe neurons are involved in mediating both of these effects. Spinally, the 5-HT3 receptor contributes to the increase and the 5-HT1A receptor to the decrease of neuropathic hypersensitivity induced by amygdaloid glutamate.
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Motor imagery (MI) and action observation (AO) are considered effective cognitive tools for motor learning, but little work directly compared their cortical activation correlate in relation with subsequent performance. We compared AO and MI in promoting early learning of a complex four-limb, hand-foot coordination task, using electroencephalographic (EEG) and kinematic analysis. Thirty healthy subjects were randomly assigned into three groups to perform a training period in which AO watched a video of the task, MI had to imagine it, and Control (C) was involved in a distracting computation task. ⋯ This beta synchrony furthermore demonstrated the strongest association with kinematic errors, which was also significantly lower in AO than in MI. These data suggest that sensorimotor activation elicited by action observation enhanced motor learning according to motor performance, corresponding to a more efficient activation of cortical resources during task execution. Action observation may be more effective than motor imagery in promoting early learning of a new complex coordination task.
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The mechanisms underlying conditioned pain modulation (CPM) are multifaceted. We searched for a link between individual differences in prefrontal cortex activity during multi-trial heterotopic noxious cold conditioning and modulation of the cerebral response to phasic heat pain. In 24 healthy female subjects, we conditioned laser heat stimuli to the left hand by applying alternatively ice-cold or lukewarm compresses to the right foot. ⋯ High anxiety and habituation of cold pain were associated with greater laser heat-induced pain during heterotopic cold stimulation. The habituation was also linked to the early cold-induced orbitofrontal responses. We conclude that individual differences in conditioned pain modulation are related to different levels of prefrontal cortical activation by the early part of the conditioning stimulus, possibly due to different levels in trait anxiety.