INFORME LA DECLARACIÓN PATRIMONIAL DEL SEÑOR CORONEL INTENDENTE DEL ESTADO MAYOR OTILIO LEANDRO CASTILLO DUARTE, PARA EL AÑO FISCAL DE 1999 MIL NOVECIENTOS

If the social pain caused by an averted or unresponsive gaze can be shown to have neural foundations, what about the reverse: the obviously compelling nature of successfully-accomplished eye-contact? And, given the general responsiveness to facial expression that this demonstrates, what are the neural mechanisms involved? Here, as in the case of the ‘piggyback’ that social separation has performed onto the mammalian pain system, an adaptive explanation has been suggested. Surveying work in the field such as that of Perrett & Mistlin (1990), Baron-Cohen draws attention to their finding that a specific cell grouping exists in the monkey superior temporal sulcus that specifically responds to the gaze direction of another animal. These cells are, therefore, responsive to the ‘state of attention of the other

individual’, and have the primary function of detecting whether the other individual is ‘looking at me’. As he points out, the evolutionary benefits of such hard-wiring are obvious: ‘It is clearly highly adaptive to become aware than another organism has you within its sights’ (Baron-Cohen, 1995:90).

Work described by Puce & Perrett (2003/4; 12) shows that similar sensitivity exists in the human posterior superior temporal sulcus, together with an ability to make fine distinctions between types of facial movements. For example, seeing a mouth

opening produces a stronger level of response than seeing one closing; equally, a different level of response is produced when observing eyes averting their gaze from the observer, compared to eyes focusing their gaze on the observer. ‘Augmented neural responses to eye aversion movements,’ they conclude, ‘may be a powerful

signal that the observer is no longer the focus of another’s attention.’ They also suggest that human brains are very sensitive to distinctions created by facial

expressions accompanying verbal or non-verbal communication in differing affective contexts, and the importance of these gesture-affect blends is also noted by Baron- Cohen:

It would seem that whenever [the Eye-Direction Detector7] detects a pair of eyes that are in mutual contact with its own, this triggers physiological arousal with pleasurable consequences. There is clear evidence of physiological arousal produced by mutual eye contact. For example, galvanic skin responses increase with mutual eye contact… and brain-stem activity has been reported in response to eye stimuli in monkeys…These measures of arousal might, of course, be indicators of positive or negative emotion. However, in the case of human infants the evidence suggests positive emotion, since eye contact reliably triggers smiling.

(op cit: 42)

Further evidence of connections between eye contact and pleasurable emotion is provided by Schilbach et al, whose fMRI study of joint attention initiatives between subjects and (virtual) partners shows important contrasts between the neural activity involved in inviting a partner to gaze at an object and the activity involved in responding to such an invitation. The latter – looking at an object gazed at by the ‘partner’8 – activates the anterior portion of the medial prefrontal cortex, whereas the former – using eye gaze to direct the partner’s attention at the object – activates the anterior ventral striatum: a neural area connected with reward processing. Findings from an additional behavioural study are consistent with this result: according to answers to post-experiment questionnaires, subjects find initiating joint attention ‘significantly more pleasant’ than responding to others’ initiative. Schilbach et al conclude (2010: 2713) that joint attention engages mechanisms that may contribute to an intrinsic motivation to engage in the interpersonal coordination of perspectives, and suggest that ‘this could be closely related to the phenomenon’s impact on human cognitive development by

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Or EDD: one component of the mind-reading model in the neuronormal, whose impairment, Baron- Cohen suggests, may help to account for some aspects of autism. Other components are the

Intentionality Detector (ID), the Shared-Attention Mechanism (SAM) that handles triadic

representations and, finally, the Theory-of-Mind Mechanism (ToMM), a ‘system for inferring the full range of mental states from behavior’ (ibid: 51).

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Who is viewed by the participant on a screen; participants are informed that these images are controlled by real persons outside the scanner, whereas they are actually computer animations.

contributing to the uniquely human motivation to engage in shared, social realities.’

A further example of neural responsiveness to eye-contact and affective reaction that he describes traces a connection between two separate brain areas associated with automatic activity. This is between the human superior temporal sulcus (STS) – one suggested site of EDD cells – and the amygdala, the area of the limbic system which generates the states of mind required for brute survival: flight, fight, and ‘excessively friendly behaviour’, or appeasement (Carter, 2000:142). Baron-Cohen cites evidence that the amygdala itself contains both face-sensitive and eye-direction-sensitive cells, in addition to those responding to facial expressions of emotion: a finding that, with other evidence, he uses to support the claim that the EDD function is located in two different nodes within a circuit that connects the amygdala and the STS region.

In a major review of the neural bases of social cognition, Adolphs (1999: 469) also emphasises the part played by the amygdala in enabling human interactivity to take place. Studies in humans and other primates, he writes, have pointed to several structures that play a key role in guiding social behaviors: among others, the amygdala, the right somatosensory-related cortex, and the ventromedial frontal cortices. ‘These structures appear to mediate between perceptual representations of socially relevant stimuli, such as the sight of conspecifics, and retrieval of knowledge (or elicitation of behaviors) that such stimuli can trigger.’ In a typical, emotionally salient real-life situation, he comments, all three will operate in parallel:

The amygdala will provide a quick and automatic bias with respect to those aspects of the response that pertain to evaluating the potentially threatening nature of the situation, or with respect to allocating processing resources to those stimuli that are potentially important but ambiguous; ventromedial frontal cortex will associate elements of the situation with elements of previously encountered situations, and trigger a re-enactment of the

corresponding emotional state; and right somatosensory-related cortices will be called upon to the extent that a detailed, comprehensive representation of the body state associated with emotional or social behavior needs to be made available.

In a later paper (2001: 235-6), Adolphs acknowledges the intricacy of these relationships – ‘The sequence of events leading from perception of a socially relevant stimulus to the elicitation of a social behavior is complex and involves multiple interacting structures’ – and suggests three possible patterns of interaction. In the first, the structures involved in social cognition may directly modulate

cognition. In the second, they may modulate emotional state, which then modulates cognition indirectly, while in the third they may ‘directly modulate perceptual processing via feedback’ – the initial input to which may be completely outside the scope of conscious awareness, as evidenced by the finding that the subliminally presented facial expressions can cause amygdala activation.

A model of facial perception that resolves some of these intricacies has been proposed by Haxby et al, who stress the neural distinctions between processing invariant aspects of faces (i.e. those that determine identity) as opposed to changeable ones (i.e. eye gaze, expression, lip movement). The first type of

representation, they suggest, is handled in particular by the fusiform gyrus, while the second is handled by the pSTS. These two regions, together with the neural area responsible for early perception of facial features, form the core of their model, which is then extended to explain the complex functioning of facial perception overall. This is accomplished, Haxby et al suggest (2000: 228) via the participation of other neural systems:

Face perception provides information that is used to access knowledge about another person, to infer his or her mood, level of interest and intentions; to direct one’s own attention to objects and events that others are looking at; and to facilitate verbal communication. The results of functional brain imaging suggest which brain regions are recruited to process some of these kinds of information. These brain regions are part of neural systems that perform other cognitive functions... However, they become part of the face perception system when they act in concert with [visual brain areas] to extract meaning from faces…

Thus extended, Haxby et al’s distributed model of face perception places a strong emphasis on the superior temporal sulcus, as it is responsible for liaising with the different brain regions that handle spatial information and that are needed to process gaze direction, speech perception, comprehension (see Note 14, below), and facial

expressions of emotion, in which the amygdala plays a part. In this way, data from one cognitive system can inform the perceptions of a second: in the case of face perception, for instance, ‘information about the emotional tone of an expression appears to facilitate the accurate recognition of expression.’ And these inter-system relationships do not stop there: the regions called upon by the core system can, in their turn, also participate in other functions by interacting with other systems. ‘For example,’ Haxby et al continue (ibid: 231), ‘intraparietal regions that act in concert with the superior temporal sulcus to mediate shifts of spatial attention in response to received gaze are also involved in directing spatial attention in response to other visual cues and, perhaps, to auditory, somatosensory, and endogenous cues, as well.’

Although the review I have given here of neuroscientific research into social interaction has been brief, it was designed to draw attention both to the extent of work in this field and to the possible extent to which brain regions associated with automatic (i.e. System 1) function are involved in such interaction. In the following two sections, however, I move away from the dual-process framework to look briefly at two other areas of research that may offer major insights into the mechanisms supporting automatic interactivity: mirror neuron theory and theory of mind (ToM).