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C P Montoya

Publications and source records attributed to C P Montoya.

7 recordsLinked to original sources
PubMed1991

The "staircase test": a measure of independent forelimb reaching and grasping abilities in rats.

A novel reaching test for the rat has been developed to assess the independent use of forelimbs in skilled reaching and grasping tasks. The apparatus is a plexiglas box with a removable baited double staircase. Food pellets are placed on the staircase and presented bilaterally at 7 graded stages of reaching difficulty to provide objective measures of side bias, maximum forelimb extension and grasping skill. In the present experiment, the apparatus was used to assess the reaching performance of rats following unilateral lesions of the sensorimotor cortex, unilateral lesions of the posterior cortex or bilateral lesions of the olfactory bulbs. The task has the advantage of objective over rating measurement, and the simplicity of the apparatus permits many animals to be tested concurrently.

Animals↗
PubMed1989

Modality specific type 2 theta production in the immobile rat.

The purpose of the present study was to compare the relative effectiveness of stimulation of different sensory modalities in eliciting Type 2 theta in the rat in the presence or absence of a ferret. Visual, auditory, and tactile stimuli were presented to rats in both conditions. Tactile stimulation produced more movement than either visual or auditory stimuli when the ferret was present. In both conditions, however, more Type 2 theta was observed in response to tactile or visual stimulation than to auditory stimulation. In the arousal condition, stimulation of tactile and auditory modalities resulted in significant increases in the amount of Type 2 theta produced. Input to the visual modality produced high levels of Type 2 theta production in both low- and high-arousal conditions. It is argued that Type 2 theta is not necessarily a precursor to movement but rather sensory processing while in a high state of arousal.

Animals↗
PubMed1987

Behavioral correlates of hippocampal type 2 theta in the rat.

Previous research has indicated that there are two types of theta activity which can be recorded from the hippocampus in most rodents. One type (type 1) of theta is correlated with voluntary movements while the second (type 2) occurs during immobility. A third waveform termed LIA (Large Amplitude Irregular Activity) occurs during more automatic behaviors, e.g., grooming, shivering or immobility. In the rabbit and guinea pig type 2 theta can readily be elicited in unrestrained animals. However, type 2 theta is rarely seen in the unrestrained rat. The purpose of the present study was to determine the stimulus conditions that are necessary for the elicitation of type 2 theta in the rat. In the present study 20 unrestrained rats were observed in the presence of a cat or a ferret. Movements by the cat or ferret produced theta in immobile rats. Sensory stimuli which did not ordinarily produce type 2 theta would reliably do so in the presence of the cat or ferret. It is hypothesized that type 2 theta in the unrestrained immobile rat occurs during sensory processing but only when the animal is in a high state of "arousal."

Acoustic Stimulation↗
PubMed1985

The effects of entorhinal cortex lesions on type 1 and type 2 theta.

The effects of bilateral entorhinal cortex lesions on type 1 and type 2 theta generation in the guinea pig were studied in the chronic preparation. EEG recordings from dentate generator zones demonstrated a decrease in the relationship between ongoing type 1 motor movements and theta generation. Before lesioning theta activity accompanied type 1 behaviors (i.e., walking and head movements) in 100% of the samples, while subsequent to lesioning theta activity was present in only 58% of the samples. In addition, prior to lesioning, type 2 theta was present in 100% of the samples taken during immobile sensory processing, e.g., tactile stimulation, while after lesioning type 2 theta was present in only 34% of the samples. Type 2 theta is selectively sensitive to disruption by atropine sulfate. In the present experiment atropine sulfate eliminated all theta activity after entorhinal lesions. Consequently as no type 1 theta appeared to be present it was argued that the entorhinal cortex is a critical route for type 1 theta. However, as the behavioral and sensory correlates of both type 1 and type 2 theta were disrupted it was suggested that the entorhinal cortex is an integral part of both systems.

Animals↗
PubMed1984

The relationship between type 2 theta and behavior.

Although there is extensive literature on the correlation between Type 1 theta activity in the hippocampus and behavior, little is known about the behavioral correlates of "Type 2" (immobility) theta. In the present study, guinea pigs were exposed to three high "arousal" situations. These situations produced reliable trains of "Type 2" theta. Atropine sulfate abolished "arousal" and Type 2 theta. In the second study, we determined whether the Type 2 theta response was produced by specific stimuli or by a generalized sensitization to incoming sensory stimuli created by the testing situation. In this study, a stimulus which had not previously elicited Type 2 theta was presented a second time after a presentation of a stimulus which did elicit Type 2 theta. The previously neutral stimulus now elicited Type 2 theta. These results were interpreted within an "arousal" theory framework.

Animals↗