Tuning low-voltage-activated A-current for silent gain modulation.

Modulation of stimulus-response gain and stability of spontaneous (unstimulated) firing are both important for neural computation. However, biologically plausible mechanisms that allow these distinct functional capabilities to coexist in the same neuron are poorly defined. Low-threshold, inactivating (A-type) K(+) currents (I(A)) are found in many biological neurons and are historically known for enabling low-frequency firing. By performing simulations using a conductance-based model neuron, here we show that biologically plausible shifts in I(A) conductance and inactivation kinetics produce dissociated effects on gain and intrinsic firing. This enables I(A) to regulate gain without major changes in intrinsic firing rate. Tuning I(A) properties may thus represent a previously unsuspected single-current mechanism of silent gain control in neurons.

The extent to which chaperone policies are used in acute hospital trusts in England.

OBJECTIVE: To determine whether the Ayling Inquiry's recommendations (2004) concerning chaperone policy implementation in acute hospital trusts in England has been implemented. METHODS: A quantitative questionnaire based on the Ayling Inquiry was posted to medical directors of all acute hospital trusts in England during December 2005 to March 2006 to determine whether their trusts had implemented the inquiry's recommendations by 1 December 2005. The same questionnaire was resent between December 2007 and March 2008 to determine whether their trusts had implemented the inquiry's recommendations by 1 December 2007. RESULTS: The total response rates were 59.4% and 47.7% for the first and second cohorts, respectively. The percentage of trusts having a chaperone policy increased from 41.3% in December 2005 to 56.5% in December 2007. By the end of 2007, 17.3% had accredited training for chaperones, 57.7% had a management lead and 71.2% of trusts formally investigated a breach of the chaperone policy, the latter being a fall from 88.4% in December 2005. Informing patients verbally of the policy was the most common method of distributing the information in both cohorts. By 1 December 2007, 50.0% of trusts did not use any resources towards their chaperone policy. Of the trusts without a chaperone policy by 1 December 2007, 52.5% intend to start a policy. CONCLUSION: Despite a public inquiry, only a small majority of acute trusts in England have a chaperone policy in place, which may have severe medico-legal repercussions in the future. Commencing a chaperone policy is a must for acute trusts and regular auditing necessary to ensure recommendations be maintained.