Neuronal activity in monkey striatum related to the expectation of predictable environmental events

Abstract

1. This study investigated neuronal activity in the striatum preceding predictable environmental events and behavioral reactions. Monkeys performed in a delayed go-nogo task that included separate time periods during which animals expected signals of behavioral significance, prepared for execution or inhibition of arm reaching movements, and expected the delivery of reward. In the task, animals were instructed by a green light cue to perform an arm reaching movement when a trigger stimulus came on approximately 3 s later (go situation). Movement was withheld after the same trigger light when the instruction cue had been red (nogo situation). Liquid reward was delivered on correct performance in both situations. 2. A total of 1,173 neurons were studied in the striatum (caudate nucleus and putamen) of 3 animals, of which 615 (52%) showed some change in activity during task performance. This report describes how the activity of 193 task-related neurons increased in advance of at least 1 component of the task, namely the instruction cue, the trigger stimulus, or the delivery of liquid reward. These neurons were found in dorsal and anterior parts of caudate and putamen and were slightly more frequent in the proximity of the internal capsule. 3. The activity of 16 neurons increased in both go and nogo trials before the onset of the instruction and subsided shortly after this signal. These activations may be related to the expectation of the instruction as the first signal in each trial. 4. The activity of 15 neurons increased between the instruction and the trigger stimulus in both go and nogo trials. These activations may be related to the expectation of the trigger stimulus independent of an arm movement. Further 56 neurons showed sustained activations only when the instruction requested a movement reaction. Activations were absent in trials in which the movement was withheld. Twenty-one of these neurons were tested with 2 different movement targets, 5 of which showed activity related to the direction of movement. These activations may be related to the preparation of movement or expectation of the specific movement triggering signal. The activity of an additional 20 neurons was unmodulated before the trigger stimulus in movement trials but increased in the interval between the no-movement instruction and the trigger stimulus for withholding the movement. These activations may be related to the preparation of movement inhibition as specific nogo reaction.(ABSTRACT TRUNCATED AT 400 WORDS)

Identifying regional activity associated with temporally separated components of working memory using event-related functional MRI

“…Additional evidence that frontostriatal neural circuitry participates in WM is provided by single unit recordings and lesion studies in animals (Apicella et al, 1992;Battig et al, 1960) and lesion and dysfunction studies in humans (Owen et al, 1997;Partiot et al, 1996). However, the role of this circuitry in WM is not understood.…”

“…However, the role of this circuitry in WM is not understood. During the delay periods of delayed-response tasks, striatal neurons exhibit sustained activity that closely resembles that of the DLPFC (Apicella et al, 1992). Such findings have led to the hypothesis that this circuitry plays a role in maintaining tonic activity of the DLPFC during maintenance periods in which information critical to a correct response is held "on line" (Goldman-Rakic, 1995;Levy et al, 1997).…”

Modeling functions of striatal dopamine modulation in learning and planning

“…/ y max } smoothly limits the firing rate y(t) to values below the maximal firing rate y max of medium spiny neurons. Medium spiny neurons fire with a maximal firing rate y max of about 6 Spikes per 100 msec (Apicella et al, 1992;Pineda et al, 1992;Nisenbaum et al 1994). A factor a = 0.3 Spikes/(100 msec * mV) is used to scale the firing rate to experimental data and is estimated from firing rates for constant current injections in the absence of dopamine agonists (estimated from figure 1 in Nisenbaum et al 1994; similar in figure 3 in Pineda et al, 1992).…”

Participation of the pedunculopontine tegmental nucleus in arousal-demanding functions

“…Some responses of PPTg neurons to behavioral signals and rewards are similar to those observed in the striatum in tasks that required either arm or saccadic movements [112,113,[172][173][174][175][176]. From this comparison, we argue that the PPTg and the striatum may share common profiles of neuronal responses in relation to the presentation and expectation of predictable behavioral events, including reward ( Figure 5).…”