Biomedical subjects

Robert M Hallock

Publications and source records attributed to Robert M Hallock.

3 recordsLinked to original sources

PubMed2006

Temporal coding in the gustatory system.

Early investigations of temporal coding in the gustatory system showed that the time course of responses in some neurons showed systematic differences across the various classes of taste stimuli, implying that the temporal characteristics of a response can convey information about a taste stimulus. Studies of temporal coding in the gustatory system have grappled with several unique methodological challenges, including the quantitative description and comparison of temporal patterns as well as the assessment of the relative contributions of spatial and temporal coding to the information contained in a response to a tastant. Other investigations have suggested that the cooperative activity among synchronously firing ensembles of taste-responsive neurons at all levels of processing in the brain can convey information about taste quality (sweet, sour, salty, bitter and umami). Behavioral studies using patterned electrical stimulation of the brain in awake animals have supported the idea that temporal coding of taste stimuli may have functional significance.

Animals↗

PubMed2006

Effects of electrical stimulation of the glossopharyngeal nerve on cells in the nucleus of the solitary tract of the rat.

Electrophysiological responses to electrical stimulation of the lingual branch of the glossopharyngeal (GP) nerve (which innervates taste buds on the caudal 1/3 of the tongue) were recorded from single cells in the rostral nucleus of the solitary tract (NTS) of anesthetized rats. Electrical stimulation was delivered as single pulses (n=55), paired-pulses (n=15) and tetanic trains (n=11). NTS cells with GP-evoked responses were also tested for responsivity to taste stimuli (0.1 M NaCl, 0.5 M sucrose, 0.01 M HCl and 0.01 M quinine HCl). Fifty-five neurons were studied: 49 cells showed GP-evoked (mean latency+/-SEM=18.0+/-1.32 ms); seven of these were taste-responsive. Spontaneous rate of these cells was low (mean+/-SEM=1.4+/-0.3 spikes per second; median=0.21 spikes per second) and many cells showed no spontaneous activity. Paired-pulse stimulation of the GP nerve in 13 rats produced both paired-pulse suppression (n=11) and paired-pulse enhancement (n=4); tetanic stimulation (25 Hz, 1.0 s) produced sustained (>20 s) increases or decreases in firing rate in 7 of 11 cells tested. Histological data suggested that GP-evoked responses recorded in the most rostral NTS were likely the result of polysynaptic connections. Cells with GP-evoked responses formed a heterogeneous group in terms of their response properties and differed from cells with evoked responses to chorda tympani (CT; which innervates taste buds on the rostral 1/3 of the tongue) nerve stimulation. These differences may reflect the respective functional specializations of the GP and CT nerves.

Action Potentials↗

PubMed2003

Temporal coding of sensation: mimicking taste quality with electrical stimulation of the brain.

Two experiments suggested that the temporal pattern of a taste response in the brain can convey meaningful information. In Experiment 1, rats avoided lick-contingent electrical stimulation of the nucleus of the solitary tract (NTS; the first synaptic relay for taste) when the temporal pattern of pulses mimicked the electrophysiological response to quinine, but not when the temporal pattern was randomized. In Experiment 2, rats avoided lick-contingent electrical stimulation of the NTS that mimicked the temporal pattern of a sucrose response following stimulation-illness pairings. This aversion generalized to sucrose but not to the other tastants; extinction of the aversion to electrical stimulation also extinguished the aversion to sucrose. Results replicate and extend previous findings (P. M. Di Lorenzo & G. S. Hecht, 1993).

Action Potentials↗