Although human temporal polar cortex (TPC), anterior to the limen insulae, is heavily involved in high-order brain functions and many neurological diseases, few studies on the parcellation and extent of human TPC are available using modern neuroanatomical techniques. The present study investigated TPC with combined analysis of several different cellular, neurochemical, and pathological markers finding that this area is not homogenous as at least six different areas extend into TPC with another area being unique to the polar region. Specifically, perirhinal area 35 extends into the posterior TPC while areas 36 and TE extend more anteriorly. Dorsolaterally, an area located anterior to the typical area TA or parabelt auditory cortex is distinguishable from area TA and defined as area TAr (rostral). The polysensory cortical area located primarily in the dorsal bank of the superior temporal sulcus, separate from area TA, extends for some distance into TPC is defined as TAp (polysensory). Anterior to the limen insulae and the temporal pyriform cortex, a cortical area, characterized by its olfactory fibers in layer Ia and lack of layer IV, was defined as temporal insular cortex and named as area TI after Beck (1934). Finally, a dysgranular TPC region which capped the tip with some extension into the dorsal aspect of the TPC is defined as temporopolar area TG. Therefore, human TPC actually includes areas TAr and TI, anterior parts of areas 35, 36, TE, and TAp, and the unique temporopolar area TG.

It has often been proposed that the vocal calls of monkeys are precursors of human speech, in part because they provide critical information to other members of the species who rely on them for survival and social interactions. Both behavioural and lesion studies suggest that monkeys, like humans, use the auditory system of the left hemisphere preferentially to process vocalizations. To investigate the pattern of neural activity that might underlie this particular form of functional asymmetry in monkeys, we measured local cerebral metabolic activity while the animals listened passively to species-specific calls compared with a variety of other classes of sound. Within the superior temporal gyrus, significantly greater metabolic activity occurred on the left side than on the right, only in the region of the temporal pole and only in response to monkey calls. This functional asymmetry was absent when these regions were separated by forebrain commissurotomy, suggesting that the perception of vocalizations elicits concurrent interhemispheric interactions that focus the auditory processing within a specialized area of one hemisphere.

Cerebral auditory areas were delineated in the awake, passively listening, rhesus monkey by comparing the rates of glucose utilization in an intact hemisphere and in an acoustically isolated contralateral hemisphere of the same animal. The auditory system defined in this way occupied large portions of cerebral tissue, an extent probably second only to that of the visual system. Cortically, the activated areas included the entire superior temporal gyrus and large portions of the parietal, prefrontal, and limbic lobes. Several auditory areas overlapped with previously identified visual areas, suggesting that the auditory system, like the visual system, contains separate pathways for processing stimulus quality, location, and motion.

Efficient attention to our environment facilitates the decisions that need to be executed in daily life. Filtering critical from noncritical information may require the neural organization of multiple brain regions. Combining lesion techniques and the rodent version of the Wisconsin card sorting task in humans, we show at least two types of attentional processing systems reside in the cingulate and prefrontal cortices depending on task demands requiring shifts of attention within or between sets of meaningful cues, respectively. This neural organization for shifting attention either within or between perceptual dimensions is task dependent, and this type of organization provides evidence of attentional systems that transcend separate modality processing systems while subdividing executive control of attention. The results suggest that the anterior and posterior cingulate cortices are critical when shifting attention to closely related meaningful cues (i.e., within a perceptual dimension or attentional set) by suppressing interference of irrelevant background information, whereas the prefrontal cortex is critical when shifting attention between disparate sets of meaningful cues (i.e., between perceptual dimensions or attentional sets) (Dias et al., 1996a,b; Birrell and Brown, 2000). Based on the theories of Mackintosh (1965Mackintosh ( , 1975; Sutherland and Mackintosh 1971), it is suggested that the cingulate cortex may be important for decreasing attention to irrelevant information. In general, attention deficit disorders affect both children and adults, and current medications may affect the prefrontal and associated parietal cortical systems more or less than the cingulate cortical system.

Basolateral (BL) amygdaloid multi-unit activity was recorded as male albino rabbits learned to avoid a foot-shock unconditioned stimulus (US) by stepping in an activity wheel to an acoustic (pure tone) warning stimulus (CS+). A second tone (CS-) of different auditory frequency than the CS+ was presented in an irregular order on half of the conditioning trials but was never followed by the US. BL amygdaloid neurons developed, in the first session of conditioning, enhanced CS-elicited discharges relative to discharges recorded during pretraining with tones and noncontingent US presentations (excitatory plasticity), and greater discharges to the CS+ than to the CS- (discriminative plasticity). The discriminative plasticity attained maximal magnitude as the rabbits reached the asymptote of behavioral discrimination, and persisted during post-asymptotic training. Peak excitatory plasticity occurred in the session of the first significant behavioral discrimination and declined during the asymptotic and post-asymptotic stages of training. Similar patterns of excitatory and discriminative plasticity in structures directly interconnected with the BL nucleus (anterior cingulate cortex; medial dorsal thalamic nucleus) and effects of lesions suggest that the neurons in these areas participate in a circuit involved in mediation of avoidance learning.