The medial septum/vertical limb of the diagonal band of Broca (MSDB) provides a major input to the hippocampus and is important for spatial memory. Both cholinergic and GABAergic MSDB neurons project to the hippocampus, and nonselective lesions of the MSDB or transections of the septohippocampal pathway impair spatial memory. However, selective lesions of cholinergic MSDB neurons using 192-IgG saporin (SAP) do not impair or only mildly impair spatial memory. Previously, intraseptal kainic acid was found to reduce levels of glutamic acid decarboxylase, a marker of GABAergic neurons, but not to alter the levels of choline acetyltransferase, a marker of cholinergic neurons. The present study further characterized the effects of kainic acid on GABAergic MSDB neurons and examined the effects of intraseptal kainic acid on spatial memory. Saline, kainic acid, SAP, or the combination of kainic acid and SAP was administered into the MSDB of rats. Spatial memory was assessed in an eight-arm radial maze and a water maze. Kainic acid destroyed GABAergic septohippocampal neurons, but spared cholinergic neurons. SAP eliminated MSDB cholinergic neurons, sparing noncholinergic neurons. Coadministration of kainic acid and SAP destroyed GABAergic and cholinergic MSDB neurons. Acquisition of the radial maze task and performance on this task with 4-h delays were unimpaired by intraseptal kainic acid or SAP, but were impaired by coadministration of kainic acid and SAP. Acquisition of the water maze task was unaffected by intraseptal kainic acid, delayed slightly by SAP, and impaired severely by coadministration of kainic acid and SAP. These results provide evidence that kainic acid at appropriate concentrations effectively destroys GABAergic septohippocampal neurons, while sparing cholinergic MSDB neurons. Furthermore, lesions of the GABAergic septohippocampal neurons do not impair spatial memory. While lesions of cholinergic MSDB neurons may mildly impair spatial memory, the combined lesion of GABAergic and cholinergic septohippocampal neurons resulted in a memory impairment that was greater than that observed after a selective lesion to either population. Thus, damage of GABAergic or cholinergic MSDB neurons, which together comprise the majority of the septohippocampal pathway, cannot totally account for the spatial memory impairment that is observed after nonselective lesions of the MSDB.

Rats were administered 192-IgG saporin (SAP) or vehicle into the medial septum-vertical limb of the diagonal band (MS-vDB). Starting 1 week later, the effects of intraseptal scopolamine, oxotremorine, and muscimol were tested in a T-maze alternation task. Choice accuracy in the absence of infusions did not differ between control and SAP-treated rats. Intraseptal scopolamine or muscimol impaired the choice accuracy of SAP-treated but not control rats. Oxotremorine impaired accuracy similarly in control and SAP-treated rats. The enhanced effects of scopolamine and muscimol produced by SAP are consistent with the hypothesis that cholinergic MS-vDB neurons are used in spatial working memory. The finding that SAP alone did not alter choice accuracy provides further evidence that cholinergic MS-vDB neurons are not necessary for spatial working memory. Thus, cholinergic MS-vDB neurons are involved in but not necessary for spatial working memory.

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Visits to the emergency department (ED) are stressful for any patient and pose special challenges and potential barriers to care for those with autism spectrum disorder (ASD). In addition, people (both children and adults) with ASD differ in their perception of, or responses to, environmental stimuli. Some people with ASD present with sensory defensiveness that is environmentally moderated, but there is a gap in our knowledge about patterns or thresholds of stimulation that kindle behavioral responses. We systematically recorded visual and auditory stimuli in an ED. Data were collected in four areas, hallway, doorway of waiting room, chair in waiting room, and treatment room, over several weeks and times of day. The mean light intensity ranged from 127 to 184 lux. There were significant differences (F = 16.77, df = 3, p > 0.001) between the five ED locations. Mean sound levels ranged from a high of 63.291 dB in the waiting room chair to a low of 51.289 dB in the treatment room. The highest consistent level of noise was recorded while sitting in the waiting room chair (60.657-63.291 dB). The findings suggest significant differences in light and sound intensity in common ED locations, with the highest mean readings of light and noise in the waiting areas. The differences and descriptions of light and sound patterns support the need for additional studies in both the measurement of the ED environment and its role in stimulating sensory defensiveness in people with ASD.