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Biomedical subjects

M Steriade

Publications and source records attributed to M Steriade.

At least 181 records · Page 10Linked to original sources
PubMed1979

Excitatory-inhibitory processes in parietal association neurons during reticular activation and sleep-waking cycle.

Excitatory-inhibitory processes of parietal association neurons were studied during reticular-induced EEG activation and natural sleep-waking cycle. The probability of antidromic invasion in long-axon cells is enhanced following midbrain reticular stimulation and during both waking (W) and desynchronized sleep (D) states compared to slow-wave sleep. The thalamically elicited inhibitory phase occurs with a shorter latency following reticular stimulation and during W and D states; this is due to the reduced duration, during all these experimental conditions, of secondary excitatory processes. The duration of the inhibitory period is shorter during reticular activation; the postinhibitory rebound occurs at shorter latencies and is sharper following reticular stimulation and during W and D states. The similarity between reticular effects and changes during both W and D states is discussed.

Animals↗
PubMed1977

Some synaptic inputs and ascending projections of lateralis posterior thalamic neurons.

(1) Some synaptic inputs and telencephalic targets of lateralis intermedius-lateralis posterior (LI-LP) thalamic neurons have been investigated in the encéphale isolé cat by recording extracellular unit discharges and focal slow waves following stimulation of cortical areas 5 and 7, center median (CM) thalamic nucleus and mesencephalic reticular formation (RF). (2) Orthodromic and/or antidromic discharges in LI-LP neurons following anterior suprasylvian stimulation are electrophysiological evidence of thalamocortical reciprocal pathway in this "association" system. A few neurons were backfired from several cortical stimulated foci at different latencies, thus suggesting the existence of LI-LP output cells with branching axons. The numerous cases of cortically elicited synaptic excitation in LI-LP cells, taken together with evidence of an unexpectedly high proportion of corticothalamic neurons found in parallel experiments of this laboratory on areas 5 and 7, support the suggestion that complex functions of the "association" cortex partially depend on its downstrem connections with thalamic integrative structures. (3) Monosynaptic and oligosynaptic excitatory projections link the brain stem reticular core with LI-LP nuclear group. For some neurons, this is a high-security pathway as shown by the ability of thalamic cells to follow at short latencies fast repetitive reticular shocks. The RF-elicited phasic excitation is followed by a period of suppressed spontaneous and evoked discharge. The excitatory projections from the upper brain stem RF to the LI-LP nuclei are discussed in relation to disfacilitatory phenomena in thalamocortical systems due to withdrawal of reticulofugal ascending activation at sleep onset.

Afferent Pathways↗
PubMed1977

Reticular influences on lateralis posterior thalamic neurons.

(1) Spontaneous firing of lateralis intermedius-lateralis posterior (LI-LP) thalamic output cells, as well as excitatory-inhibitory sequences elicited in LI-LP neurons by anterior suprasylvian cortical and center median (CM) thalamic stimulation were studied in encéphale isolé preparations during control periods of EEG synchronization and during EEG activation induced by stimulating the mesencephalic reticular formation (RF). (2) Mean rate of spontaneous firing of identified thalamocortical neurons increased during spontaneous or RF-induced EEG activation and decreased during EEG synchronization, occuring spontaneously or elicited by hypocapnia. Compared with the sustained firing during EEG activation, discharge patterns of output cells during EEG synchronization were characterized by very short (less than 5 msec) and very long (greater than 1 sec) interspike intervals, and by a class of intervals reflecting rhythmic (2.5-4/sec) periods of neuronal silence between high-frequency spike bursts. (d) The following effects were exerted by a short conditioning mesencephalic RF stimulation on cortically evoked events in single LI or LP thalamic neurons: (a) increased probability of the early, antidromically or orthodromically elicited discharges; (b) decreased probability of late (15-25 msec) discharges; (c) shortened latency of the subsequent inhibitory period; (d) reduction in the duration of the first inhibitory phase, and blocking of subsequent, cyclic inhibitory pauses as well as disorganization of postinhibitory clustered excitation.

Afferent Pathways↗
PubMed1976

Cortically elicited spike-wave after discharges in thalamic neurons.

Self-sustained, 3-4/sec spike-wave ADs were elicited in lateralis intermedius-lateralis posterior thalamic bursting neurons following incremental responses elicited by 10/sec shock-trains applied to the anterior suprasylvian cortex. The pattern of cortically elicited thalamic spike-wave complexes, with brief depolarizing components and a long-lasting hyperpolarizing wave, resembles that of previously described spike-wave seizures elicited in cortical interneurons following specific thalamo-cortical augmenting responses.

Animals↗