From Synchrony to Harmony: Ideas on the Function of Neural Assemblies and on the Interpretation of Neural Synchrony

Why spikes? Hebbian learning and retrieval of time-resolved excitation patterns

“…Since the determination of the mean firing rate requires an average over a sufficiently long time interval (typically 100 ms and more), all information about the exact firing times of a single neuron is lost. The firing time of a neuron compared with the start of a stimulus or the spikes of other neurons could, however, be of great importance for correct interpretation of the stimulus (Perkel et al 1967;Gerstein and Perkel 1972;Abeles 1982;Aertsen et al 1986;Johannesma et al 1986;Palm et al 1988). Indeed, it has been shown in experiments on the fly that the timing of a single spike becomes important if one attempts to decode the spike train and reconstruct the stimulus (Bialek et al 1991).…”

Testing non-linearity and directedness of interactions between neural groups in the macaque inferotemporal cortex

“…Singer and Gray (1995); Engel et al, (1997) for recent reviews). According to this conceptual framework as well as to similar ones (Johannesma et al, 1986;Gerstein et al, 1989;Aertsen et al, 1991;Sporns et al, 1991;Ahissar et al, 1992;Prut et al, 1998), neural interactions change in relation to current processing requirements defined by external stimuli and the internal behavioural state of the animal. Much previous work related to these concepts has focused on the strength of neural interactions as indicated by correlation measures.…”

Seven Principles for Command and the Neural Causation of Behavior

“…For exam ple, future research might show that a given com mand system mediates a particular type of tensorial transformation [Pellionisz, 1986;Peterson et al, 1988], displays characteristics of chaotic systems [Johannesma et al, 1986;Mpitsos and Cohan, 1986], or is self-organizing [Kohonen, 1984]. Our concept pro vides a framework in which such theories can be in corporated in understanding how behavior patterns are initiated.…”

“…Command neurons, according to this concept, are defined within the confines of a reactive system in which information flow is a linear, serial sequence from input to output [for a discussion of reactive systems, see Johannesma et al, 1986], In reality, neural circuits look more like those shown in figure 6. b. Neural circuits have both internal and external feedback loops, lateral interac tions and feedforward. 'A neural network model can not reflect genuine collective phenomena, unless in its analysis the feedback through many different paths is taken into account: in a collective model the activity of every component of a system then depends on the activities of many other components' [Kohonen.…”

“…a Linear, reactive circuit for which the C'NE was designed is shown, b Creative circuit with internal feedback loops that more adequately portray neural network design is depicted. Such circuits defy the analytical methods of N&S causation [Eaton and DiDomenico, 19851 and the two types of circuits have distinct mathemat ical descriptions [figure from Johannesma et al, 1986). tion is localized only in a metaphorical sense. These principles are offered in contrast to the features of the CNE.…”