Noninvasive functional MRI in alert monkeys

Noninvasive functional MRI in alert monkeys

Functional magnetic resonance imaging (fMRI) is now widely used to study human brain function. Alert monkey fMRI experiments have been used to localize functions and to compare the workings of the human and monkey brains. Monkey fMRI poses considerable challenges because of the monkey's small brain and naturally uncooperative disposition. While training can encourage monkeys to be more obliging...

Functional Magnetic Resonance Imaging In Alert Behaving Monkeys

Modeling V1 complex cells in alert monkeys

Abstract. Cortical complex cells are usually described as nonlinear energy operators that sum squared outputs of quadrature pairs of linear subunits, responding to drifting sinusoidal gratings with unmodulated elevation of firing rate (F0 harmonic). However, several lines of evidence suggest that the view of complex cells as a uniform class is over-simplified, since energy models do not capture...

Orientation and direction selectivity of neurons in V1 of alert monkeys: functional relationships and laminar distributions.

We studied orientation selectivity in V1 of alert monkeys and its relationship to other physiological parameters and to anatomical organization. Single neurons were stimulated with drifting bars or with sinusoidal gratings while compensating for eye position. Orientation selectivity based on spike counts was quantified by circular variance and by the bandwidth of the orientation tuning curve. T...

Unit activity in accessory optic system in alert monkeys.

An accessory optic fiber system was only recently demonstrated unequivocally in the primate. Fiber bundles branch off the primary optical pathway, synapse in the accessory optic nucleus, and continue to the nucleus of the transpeduncular tract in the rostroventral region of the midbrain medial to the substantia nigra and ventromedial to the red nucleus.-' •' In exploring midbrain structures of ...