To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
A Turing degree d is the degree of categoricity of a computable structure
if d is the least degree capable of computing isomorphisms among arbitrary computable copies of
. A degree d is the strong degree of categoricity of
if d is the degree of categoricity of
, and there are computable copies
such that every isomorphism from
computes d. In this paper, we build a c.e. degree d and a computable rigid structure
such that d is the degree of categoricity of
, but d is not the strong degree of categoricity of
. This solves the open problem of Fokina, Kalimullin, and Miller .
For a computable structure
, we introduce the notion of the spectral dimension of
, which gives a quantitative characteristic of the degree of categoricity of
. We prove that for a nonzero natural number N, there is a computable rigid structure
is the degree of categoricity of
, and the spectral dimension of
is equal to N.
The interplay between the intrinsic properties of thalamocortical (TC) neurons and synaptic potentials was investigated in vivo, in decorticated and intact-cortex cats, as well as in computational models to elucidate the possible mechanisms underlying the disruption of the spindle oscillation, a network phenomenon. We found that the low-threshold spikes (LTSs) in TC neurons were graded in their amplitude and latency to peak when elicited by current pulses or synaptic potentials from physiological levels of hyperpolarization. IPSPs could either delay or shunt the LTSs. Although the onset of spindles was rhythmic and did not include rebound LTSs, the end of spindles was highly aperiodic suggesting that desynchronization could contribute to the spindle termination. The desynchronization could have several sources, the main of which are (a) intrinsically generated rebound LTSs in TC neurons that occur with different delays and keep thalamic reticular (RE) neurons relatively depolarized, and/or (b) out-of-phase firing of cortical neurons due to intracortical processes that would result in depolarization of both TC and RE neurons. The present study suggests that an active cortical network participates in disrupting the spindle activities. We propose that the progression of spindles contains at least three different phases, with different origins: (a) the onset is generated by RE neurons that impose their activity onto TC neurons, without participation of cortical neurons; (b) the middle part is produced by the interplay between RE and TC neurons, with potentiation from the cortical network; and (c) the waning of spindles is due to the out-of-phase firing of TC and particularly cortical neurons that participate in the spindle termination.
Email your librarian or administrator to recommend adding this to your organisation's collection.