The purpose of this study was to identify the afferent link in the neural pathway which mediates emotional responses coupled to auditory stimuli. We evaluated whether autonomic and behavioral responses elicited by acoustic conditioned emotional stimuli are based on afferent information derived from the auditory cortex or from the auditory thalamic relay station, the medial geniculate nucleus (MG), in rats. The rat auditory cortex was defined through anterograde neuroanatomical tracing studies involving the injection of HRP into MG. Lesions were then placed in the auditory cortex or in MG. After 10 to 20 days the rats were subjected to classical fear conditioning trials involving the pairing of a pure tone with electric footshock. Changes in mean arterial pressure and heart rate and the duration of immobilization ("freezing") and drink suppression elicited by presentation during extinction trials (no footshock) of the acoustic conditioned emotional stimulus were measured. Auditory cortex lesions did not affect the magnitude of the mean arterial pressure or heart rate conditioned responses nor the duration of freezing or drink suppression. In contrast, lesions of MG suppressed the magnitude of both the autonomic and somatomotor (behavioral) conditioned emotional responses but did not affect either autonomic or somatic responses elicited by the footshock unconditioned stimulus. Lesions of the inferior colliculus, the primary source of afferent input to MG, replicated the effects of MG lesions. These findings demonstrate that lesions of MG and lower auditory centers, but not lesions of the auditory cortex, block autonomic and behavioral conditioned emotional responses coupled to acoustic stimuli and indicate that subcortical rather than cortical efferents of MG sustain these responses. Our concurrent observation that MG projects to several subcortical areas (central and lateral amygdala; caudate-putamen; ventromedial hypothalamus) involved in emotional behavior and autonomic function suggests hypotheses concerning subsequent links in this emotional processing pathway.

The complex formation of bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) with 29 organic electron acceptors and six organic anions yielded 37 charge-transfer (CT) complexes, about three-quarters of which exhibited metallic behavior. The BEDO-TTF molecule proves to be an excellent source for stable metals irrespective of the structure, shape, size, and electron affinity of counter components. The crystal structure of metallic BEDO-TTF complexes indicates a strong aggregation of donor molecules into a two-dimensional (2D) layered structure by the aid of both intermolecular CH···O and side-by-side heteroatom contacts. Band calculations based on an extended Hückel method demonstrate that the sulfur atoms of the BEDO-TTF molecule are dominant for 2D intermolecular overlap. The resulting 2D electronic bands with large band width serve to stabilize the metallic state even at low temperatures. A comparison between the structural properties of complexes of BEDO-TTF and those of its sulfur analog BEDT-TTF (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) demonstrates that the oxygen atoms of the BEDO-TTF molecule not only enhance the intermolecular S··S atomic contacts due to its small size, but also determine donor packing through multiple weak hydrogen bondings. The nicely combined roles of these heteroatoms are the origins of the strongly stabilized metallic state in BEDO-TTF complexes without aid of heavier selenium and/or further addition of sulfur atoms on TTF moiety.

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SUMMARY Spontaneously hypertensive rats (SHRs) and Wistar Kyoto controls (VVKYs) were chronically instrumented for computer-assisted recording of arterial pressure (AP) and heart rate (HR) and examined during classically conditioned emotional (fear) reactions or during the performance of a repertoire of natural behaviors, including eating, drinking, grooming, exploring, and resting. The purpose of the study was to determine whether exaggerated cardiovascular reactivity in SHRs during aversive stimulation: 1) can be coupled to stimuli that before conditioning elicited negligible changes in AP and HR; 2) is accompanied by a proportionately enhanced level of emotional arousal; and 3) is specific to aversive emotional arousal or is also present during natural behaviors. The conditioned blood pressure response (in mm Hg) was greater (p < 0.01) in SHRs (peak response, 20 ± 3) than in WKYs (peak response, 7 ± 1). While the conditioned pressure response was accompanied by bradycardia in WKYs (peak response, -1 3 ± 5 bpm), tachycardia was present in SHRs (peak response, 17 ± 7 bpm). Behavioral tests indicated reduced emotional reactions in SHRs: SHRs showed less (p < 0.05) drink suppression (75 ± 17 sec) than WKYs (111 ± 10 sec) and SHRs showed less (p < 0.01) suppression of exploratory activity (201 ± 40 sec) than WKYs (499 ± 70) in the presence of the conditioned emotional stimulus. The magnitude of blood pressure changes (in mm Hg) above resting baseline was not different in SHRs and WKYs during eating (SHR, 32 ± 3; WKY, 28 ± 2), grooming (SHR, 17 ± 3; WKY, 14 ± 2), or exploring (SHR, 17 ± 2; WKY, 18 ± 2), but was greater (p < 0.01) during drinking in SHRs (48 ± 4) than in WKYs (32 ± 2). The amount of time (sec) spent grooming (SHR, 55 ± 23; WKY, 38 ± 15) and exploring (SHR, 187 ± 33; WKY, 165 ± 42) did not differ between the strains, but SHRs spent more time (p < 0.01) eating (SHR, 1103 ± 88; WKY, 800 ± 114) and drinking (SHR, 119 ± 18; WKY, 32 ± 12). These findings demonstrate that: 1) exaggerated cardiovascular reactivity in SHRs is readily coupled through conditioning to otherwise benign stimuli; 2) conditioned cardiovascular hyperreactivity is accompanied by a reduced not an enhanced level of conditioned emotional arousal; 3) cardiovascular hyperreactivity is not specific to aversive arousal but is nevertheless a behaviorally-specific mode of response; and 4) SHRs and WKYs differ in the performance of natural as well as emotional behaviors. (Hypertension 4: 853-863, 1982) KEY WORDS • blood pressure • natural behavior • conditioned emotional responses • spontaneously hypertensive rats • classical conditioning A RTERIAL pressure (AP) changes associated with aversive emotional arousal are exaggerated in spontaneously hypertensive rats (SHRs) when compared with strain-matched WistarKyoto controls (WKYs): during the acute or chronic presentation of aversive stimuli, such as electric foot-