Behavioural brain research
-
Comparative Study
The differential effects of cervical and thoracic dorsal funiculus lesions in rats.
The purpose of this research was to compare the locomotor abilities of rats with cervical dorsal spinal funicular (DF) lesions to those of rats with the same lesion at the mid-thoracic level. The dorsal funiculus, consisting of ascending sensory fibers and the main component of the corticospinal tract, was transected either at spinal level C2 or at T8. We examined limb force generation and limb timing and coordination during overground locomotion, as well as foot placement errors during locomotion over a horizontal ladder. ⋯ DF lesions at cervical vs. thoracic levels thus have differential effects on locomotor abilities in rats. We compare these results with previous work and suggest that the differential response to DF transection might be related to both functional distinctions between the fore- and hindlimbs and to anatomical differences in the dorsal funiculi at different spinal levels. These findings have implications for the mechanisms of recovery as well as the types of behavioural tests which can be practically used to measure functional changes in different lesion models.
-
It is widely acknowledged that the indoleamine neurotransmitter serotonin (5-HT) plays a dual role in the regulation of anxiety, a role that in part depends upon neuroanatomical locus of action. Thus, whereas stimulation of 5-HT 1A or 5-HT2 receptors in the limbic forebrain (amygdala, hippocampus) enhances anxiety-like responding in rodents, activation of corresponding receptor populations in the midbrain periaqueductal grey (PAG) more often than not reduce anxiety-like behaviour. The present study specifically concerns the anxiety-modulating influence of 5-HT2 receptors within the mouse PAG. ⋯ The results of Experiment 1 showed that mCPP microinfusions (0.03 and 0.1 nmol) into the PAG of mice decreased behavioural indices of anxiety without significantly altering general activity measures. In Experiment 2, the anxiolytic-like profile of intra-PAG mCPP (0.03 nmol) was substantially attenuated by intra-PAG pretreatment with an intrinsically inactive dose of the preferential 5-HT2A/2C receptor antagonist, ketanserin (10 nmol/0.1mul). Together, these data suggest that 5HT2C receptor populations within the midbrain PAG play an inhibitory role in plus-maze anxiety in mice.
-
Caffeine produces effects on cognitive function particularly relating to aspects of attention such as reaction time. Considering the plasma exposure levels following regular caffeine intake, and the affinity of caffeine for known protein targets, these effects are likely mediated by either the adenosine A(1) or A(2A) receptor. In the present studies, two rat strains [Long-Evans (LE) and CD] were trained to asymptote performance in a test of selective attention, the 5-choice serial reaction time task (5-CSRTT). ⋯ Interestingly, at a comparatively low dose of 0.03 mg/kg, CGS-21680 attenuated the increased premature responding produced by amphetamine (1mg/kg IP). The present results suggest that the attention-enhancing effects of caffeine are mediated through A(2A) receptor blockade, and selective A(2A) receptor antagonists may have potential as therapies for attention-related disorders. Furthermore, the improvement in response control in amphetamine-treated rats following CGS-21680 pretreatment supports the view that A(2A) agonists have potential as novel antipsychotics.
-
Although we demonstrated willed movement (WM) therapy can facilitate the patients actively participating in the physical activities by cognitive and perceptual stimulation in our previous study, the molecular mechanisms of the willed movement on the patients remains unclear. We initially established the model of WM intervention for rats and identified possible effects of willed movement on motor recovery and on expression of Kainate/alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in ischemia core (IC) and ischemia penumbra (IP) regions of rats after cerebral ischemia reperfusion. ⋯ Early willed movement treatment can increase the expression level of AMPA receptor subunits and thus might increase synaptic transmission and enhance brain plasticity after focal brain ischemia at the subacute stage.
-
Comparative Study
Gender associations with chronic methylphenidate treatment and behavioral performance following experimental traumatic brain injury.
Evidence suggests that dopamine (DA) agonists improve cognition after traumatic brain injury (TBI). Methylphenidate (MPH) is a DA agonist that blocks the dopamine transporter (DAT). Moreover, female sex hormones modulate DAT expression. ⋯ Further, injured females treated with MPH had faster swimming speeds than all other groups (P<0.05 all comparisons), and MPH increased activity in TBI females but not males in the FCN task (P<0.05). These results suggest that MPH is beneficial after TBI. However there are gender specific drug differences in behavioral performance and sensitivity to treatment with MPH that may have implications for treatment efficacy and dosing clinically after TBI.