Sodium Carbonate is Saltier Than Sodium Chloride to Sodium-Depleted Rats.

In a series of behavioral experiments in the 1960s, G.R. Morrison identified several unique features of the taste of Na2CO3 to rats; namely, it is 1) considerably more intense than NaCl at isomolar concentrations, 2) avoided at 10 times lower concentrations than NaCl to thirsty rats, 3) preferred at 10 times lower concentrations than NaCl in sodium-depleted rats. He also demonstrated its qualitatively similarity to NaCl. In Experiment 1, we confirmed and extended many of Morrison's observations. Rats were injected with furosemide on 3 occasions to stimulate a sodium appetite. After each depletion, rats were given a brief-access taste test in a lickometer presenting, in random order, water and 7 concentrations of salt. One test used NaCl (0.028-0.89 M, quarter log steps), another used Na2CO3, and the third used Na2CO3, but at a tenfold lower concentration range (0.0028-0.089 M). Rats licked NaCl in an inverted-U shaped concentration-response function peaking at 0.158-0.281 M. As Morrison's results predicted, rats licked Na2CO3 in nearly identical fashion, but at a tenfold lower concentration range (peak at 0.0158-0.028 M). In a second experiment, furosemide-treated rats were repeatedly tested with the lower Na2CO3 range but mixed in the epithelial sodium channel blocker amiloride at various concentrations (3-300 µM, half log steps). Amiloride reduced licking for Na2CO3 and shifted the peak response rightward up to about half a log unit. Thus, this "super-saltiness" of Na2CO3 to rats is at least partly amiloride-dependent.

The association between brain volumes, delirium duration, and cognitive outcomes in intensive care unit survivors: the VISIONS cohort magnetic resonance imaging study*.

OBJECTIVE: Delirium duration is predictive of long-term cognitive impairment in intensive care unit survivors. Hypothesizing that a neuroanatomical basis may exist for the relationship between delirium and long-term cognitive impairment, we conducted this exploratory investigation of the associations between delirium duration, brain volumes, and long-term cognitive impairment. DESIGN, SETTING, AND PATIENTS: A prospective cohort of medical and surgical intensive care unit survivors with respiratory failure or shock. MEASUREMENTS: Quantitative high resolution 3-Tesla brain magnetic resonance imaging was used to calculate brain volumes at discharge and 3-month follow-up. Delirium was evaluated using the confusion assessment method for the intensive care unit; cognitive outcomes were tested at 3- and 12-month follow-up. Linear regression was used to examine associations between delirium duration and brain volumes, and between brain volumes and cognitive outcomes. RESULTS: A total of 47 patients completed the magnetic resonance imaging protocol. Patients with longer duration of delirium displayed greater brain atrophy as measured by a larger ventricle-to-brain ratio at hospital discharge (0.76, 95% confidence intervals [0.10, 1.41]; p = .03) and at 3-month follow-up (0.62 [0.02, 1.21], p = .05). Longer duration of delirium was associated with smaller superior frontal lobe (-2.11 cm(3) [-3.89, -0.32]; p = .03) and hippocampal volumes at discharge (-0.58 cm(3) [-0.85, -0.31], p < .001)--regions responsible for executive functioning and memory, respectively. Greater brain atrophy (higher ventricle-to-brain ratio) at 3 months was associated with worse cognitive performances at 12 months (lower Repeatable Battery for the Assessment of Neuropsychological Status score -11.17 [-21.12, -1.22], p = .04). Smaller superior frontal lobes, thalamus, and cerebellar volumes at 3 months were associated with worse executive functioning and visual attention at 12 months. CONCLUSIONS: These preliminary data show that longer duration of delirium is associated with smaller brain volumes up to 3 months after discharge, and that smaller brain volumes are associated with long-term cognitive impairment up to 12 months. We cannot, however, rule out that smaller preexisting brain volumes explain these findings.

Feedback and reward processing in high-functioning autism.

Individuals with high-functioning autism often display deficits in social interactions and high-level cognitive functions. Such deficits may be influenced by poor ability to process feedback and rewards. The feedback-related negativity (FRN) is an event-related potential (ERP) that is more negative following losses than gains. We examined FRN amplitude in 25 individuals with Autism Spectrum Disorder (ASD) and 25 age- and IQ-matched typically developing control participants who completed a guessing task with monetary loss/gain feedback. Both groups demonstrated a robust FRN that was more negative to loss trials than gain trials; however, groups did not differ in FRN amplitude as a function of gain or loss trials. N1 and P300 amplitudes did not differentiate groups. FRN amplitude was positively correlated with age in individuals with ASD, but not measures of intelligence, anxiety, behavioral inhibition, or autism severity. Given previous findings of reduced-amplitude error-related negativity (ERN) in ASD, we propose that individuals with ASD may process external, concrete, feedback similar to typically developing individuals, but have difficulty with internal, more abstract, regulation of performance.

Error processing in high-functioning Autism Spectrum Disorders.

Studies report error-processing abnormalities in high-functioning individuals with Autism Spectrum Disorders (ASD) that may be influenced by intelligence and autism severity. Error processing can be measured using the error-related negativity (ERN) and post-error positivity (Pe) components of the event-related potential (ERP), along with behavioral indices such as post-error reaction time (RT) slowing. We used a modified Flanker task to test the hypothesis that high-functioning individuals with ASD would show decreased amplitude ERN in 24 individuals with ASD and 21 age- and IQ-matched typically-developing control participants. Behaviorally, individuals with ASD committed more errors than controls, but groups did not significantly differ on RTs, although there was a trend-level difference in post-error slowing. For ERPs, ERN amplitude was significantly attenuated in individuals with ASD relative to controls; groups did not differ in Pe amplitude. Amplitude of the ERN was not significantly correlated with measures of intelligence, anxiety, behavioral inhibition, or general autism severity.