Neuronal activity within the nucleus basalis and conditioned neocortical electroencephalographic activation

Abstract

The relationship between neuronal activity within the nucleus basalis (NB) and conditioned neocortical EEG activation was investigated in New Zealand rabbits during Pavlovian differential conditioning. Twenty- seven of 56 neurons recorded in conditioned animals demonstrated a significantly greater change in activity to a tone (CS+) that predicted the occurrence of a mildly aversive unconditioned stimulus when compared to a tone (CS-) that did not. Twenty-four of these 27 neurons demonstrated a significant increase in activity to the CS+ compared to the CS-, while the remaining three neurons demonstrated a significant decrease in activity to the CS+ compared to the CS-. In 24 of these 27 neurons (89%) these changes in neuronal activity during CS presentations correlated significantly with a decrease in the power of delta activity in the EEG. In addition, 13 of these 24 neurons (54%) demonstrated significant correlations between neuronal activity and the power of delta activity during CS-free periods. In experimentally naive animals, the activity of 10 of 22 neurons (45%) recorded within the region of the NB correlated with the power of delta activity in the EEG during stimulus-free periods. These results complement a growing body of evidence and provide strong support for the hypothesis that the NB contributes to neocortical activation in the conscious animal.

Multiple Nicotinic Acetylcholine Receptor Subtypes in the Mouse Amygdala Regulate Affective Behaviors and Response to Social Stress

“…Rather, ACh acting through nAChRs at baseline could be required for normal amygdala function, and decreasing cholinergic activity in this structure could be protective against changes in neurotransmitter systems at other brain sites in response to stress, including changes in α7-regulated glutamatergic projections (Yang et al, 2013). This would be consistent with electrophysiological studies demonstrating that cholinergic neurons of the nucleus basalis, a major source of ACh to the amygdala, have a high firing rate when animals are awake, leading to a high level of baseline cholinergic signaling in the amygdala even in the absence of a stressor (Whalen et al, 1994). This is also consistent with the observation that inescapable stress increases extracellular ACh levels in the hippocampus as measured by microdialysis, but has little effect on ACh levels in the amygdala (Mark et al, 1996).…”

Neural bases of the non-conscious perception of emotional signals

“…Moreover, there is currently no evidence about the involvement of the substantia innominata during non-conscious perception of emotional stimuli in patients with cortical blindness or about its role in attentional unawareness. Several studies have reported activity in the substantia innominata in response to consciously perceived emotional stimuli 84,85 . This activity differs from the amygdala, however, in that it seems to respond more to the arousal rather than the emotional valence of the stimuli 85,86 .…”

“…Several studies have reported activity in the substantia innominata in response to consciously perceived emotional stimuli 84,85 . This activity differs from the amygdala, however, in that it seems to respond more to the arousal rather than the emotional valence of the stimuli 85,86 . The nucleus accumbens (or ventral striatum) has been implicated in reward processing and it is activated even by non-consciously perceived omissions of expected rewards 87 .…”

The Cholinergic Lesion of Alzheimer's Disease: Pivotal Factor or Side Show?

“…There is somewhat more consistent evidence that the cholinergic pathway from the nucleus basalis to the amygdala may enhance memory consolidation, especially of affectively salient events (McGaugh et al 1993;Everitt and Robbins 1997;Power et al 2002). Furthermore, during Pavlovian conditioning, approximately half of the nucleus basalis neurons show a significantly greater change of activity in response to a tone that predicts the occurrence of a mildly aversive unconditioned stimulus than to a tone that does not (Whalen et al 1994).…”