Parallel Spike Research Articles

A low-cost single-board solution for real-time, unsupervised waveform classification of multineuron recordings

We describe a low-cost single-board system for unsupervised, real-time spike sorting of recordings from a number of neurons on a single microelectrode. The maximum number of spike classes depends on the quality of the recording; it will typically be between 2 and 5. The spike sorter communicates with a conventional microcomputer through a standard serial port (RS232). For typical firing rates as measured in the mammalian central nervous system, this set-up will accommodate up to some 10 parallel spike sorters for as many separate microelectrodes.

Interictal spiking increases after seizures but does not after decrease in medication

In patients with focal epilepsy, EEG spike rate fluctuates considerably over time. We had previously shown that seizure occurrence played an important role in these fluctuations. We undertook this study to confirm this finding with better control of critical variables such as state of alertness and spike quantification, and to assess the spatial extent of the changes. Background activity changes and antiepileptic drug levels were also examined in relation to spiking. Spike discharge rate increased in the hours and days following seizures in widespread brain regions including, but not restricted to, the seizure focus. Spike rate did not change systematically before seizures. Postictal changes in background activity did not parallel spike fluctuations. Decreased antiepileptic drug levels did not cause increased spike rate. These results indicate that, following seizures, there is activation of interictal spiking which is not paralleled by changes in background activity. It is most often widespread and not necessarily most prominent at the site of seizure onset.

Electrically coupled intrinsic responses of feline lower esophageal sphincter.

Intraluminal pressures and serosal myoelectric activity were recorded simultaneously from the esophagus, lower esophageal sphincter (LES), and stomach of chloralose-anesthetized cats. The LES demonstrated intermittent spike activity basally without slow waves and was distinct from esophagus and fundus. LES spike activity was not correlated with basal sphincter pressure. Dose-dependent increases in both spikes and pressure occurred with bethanechol, phenylephrine, or pentagastrin. Increased spike activity preceded the onset of the pressure rise and peaked during the rise in pressure. Changes in LES pressure and spike activity following these agents were correlated closely (r = 0.92, P less than 0.01). Atropine and isoproterenol inhibited pressure and spike activity similarly. Intrinsic reflexes to endogenous stimuli gave parallel spike and pressure changes. Distal esophageal acidification produced an increase in LES pressure that was correlated with increased spike activity. LES spike activity and pressure were inhibited similarly by antral distension or gastric acidification. Dissection of the distal esophagus from the diaphragm or bilateral cervical vagotomy had no effect on either LES spike activity or pressure. These studies indicate that a) LES myoelectric activity consists of spike discharges that are not correlated to resting pressure, b) abrupt changes in sphincter pressure following either intrinsic reflexes or neurohormonal agents are closely associated with similar changes in spike activity, and c) spike activity and sphincter pressure are intrinsic to the LES.