Riassunti Affective Neurosciences

Neural systems involved in emotion regulation.

Three types of neural systems are primarily involved in generating and applying reappraisals. The most

subcortical regions to be modulated are the amygdala and the striatum.

• Dorsolateral and posterior prefrontal cortex, along with inferior parietal regions generally

implicated in selective attention and working memory.

• Dorsal regions of the anterior cingulate cortex implicated in performance monitoring may help

track the extent to which one's current reappraisals are changing emotional responses in the

intended way.

• Regions of ventrolateral prefrontal cortex implicated in selecting goal - appropriate ( and

inhibiting goal inappropriate ) responses and information from semantic memory.

The most common goals when using reappraisal is to decrease negative emotion but also increase

thereby anxiety, worry, rumination. Decreasing emotional response needs more demand than increasing

it. It's more difficult, and active more areas > PFC right and left. ( only left for the increasing ). Right

dorsal might also be involved in the inhibition of a first appraisals in favor of a selection of a new one,

meanwhile in incresing goals six studies show the activation of the anterior dmPFC.

Decreasing and increasing goals ( emotional responses ) also activates ventral and dorsal striatum

( caudate and putamen ). Decrease goals reliably modulate the amygdala's ventral ( corresponding to

the basal and lateral amygdala nuclei ) and dorsal portions ( central nucleus ) as well as the

subletincular extended amygdala that lies between the amygdala and the striatum. On the other hand

increasing goals may modulate only the dorsal amygdala/SLEA. One speculative interpreations of

these data is that decrease goals influence perceptual and semantic inputs to the amygdala, which come

through the basolateral complex, whereas increase goals influence the outputs of the amygdala, which

flow from the central nucleus.

There are two reappraisals tactics : Reinterpretation and distancing.

The first involves changing one's interpretation of the elements of the situation or stimulus that elicits

emotion. The second involves changing one's personal connection to, or psychological distance from,

the stimulus that elicits emotion. Reinterpretation seems to differentially call upon ventral lateral

prefrontal regions implicated in response selection and inhibition. Second, distancing seems to recruit

parietal regions implicated in spatial attention and representation to a greater extent, including

perspective taking and the sense of agency. This may reflect the fact that distancing involves changing

the conceptual and spatiotemporal perspective from which stimuli are experienced. Third, the regions

involved in reinterpretations appear to be more strongly left lateralized in prefrontal and temporal

cortices, whereas regions involved in distancing appear to be more strongly right lateralized in

prefrontal cortex. These patterns may reflect the differential dependence of reinterpretation and

distancing on linguistic and semantic processes as ossoded to spatial and attentional processes, which

generally show a left versus right hemisphere pattern of relative specialization.

Research method in Affective Neurosciences

• Animal studies

• Human studies

 Patients with focal brain lesions, with psychopathological disorders, and healthy individuals

○ Structural neuroimaging (CT, MRI, DTI…)

○ Functional neuroimaging (fMRI, PET, SPECT, NIRS)

○ Brain electric and magnetic activity (dense-array EEG

and MEG estimation of cortical sources)

○ Combined EEG/fMRI, MEG/fMRI, EEG/PET, MEG/PET

Rodents (rats, mice, hamsters), cats (rare over recent decades), nonhuman primates (rhesus macaque).

Lesions of specific brain areas can be produced by surgical removal, aspiration, high frequency current,

or neurotoxins.

 Manipulations of brain structures to cause or alter the expression of emotion

 stereotactically-placed lesions

 electrical stimulation

 pharmacological activation or inhibition of neurotransmitter receptors by drugs delivered either

systemically or by microinjection into a brain structure

 Measures of neural activity correlated to naturally induced emotion

 surgically-implanted microelectrodes to record the firing patterns

of single neurons or groups of neurons

 neurochemical measures to detect changes in the extracellular

concentration of neurotransmitters (microdialysis).

Human studies: in-vivo brain imaging.Functional neuroimaging techniques allow the visualization of a

person’s brain activity while the individual whose brain is being imaged engages in a psychological

activity of interest. Previously, studies of brain structures and functions associated with psychological

states and processes were limited to animal models, post-mortem examinations, electrophysiological

measures, and observations of individuals who suffered traumatic injury to, or disorders of, the brain.

The goals of neuroimaging

• Neuro-anatomical localization of emotional & cognitive processes. The goal is to determine which

particular brain regions or systems exhibit a change in activity in response to the engagement of a

particular emotional/cognitive/sensory process

• Testing theories of cognition/emotion. The goal is to test one particular theory expressed in cognitive

terms, or to adjudicate between competing theories

• Testing neural models. The goal is to test a proposal as to which regions of the brain are activated

when some task is being performed, what pathways of communication are used between these regions,

and what the functional strengths of these pathways are.

Is neuroimaging “modern phrenology”?

The goal of localization (mapping psychological functions to anatomical structures) in brain imaging

research has been criticized as a modern version of 19th century phrenology. Every process has its

place in the brain: fear is in the amygdala, memory is in the hyppocampus, etc. But if a brain area is

activated when a certain process takes place, does it mean that there is a one-to-one mapping between

that area and that computation? Is the human mind/brain composed of a set of highly specialized

components, each carrying out a specific computation, or is it more of a general-purpose device, in

which each component participates in a wide variety of cognitive and affective processes? The concept

of functional specialization is not all-ornone but a matter of degree; a cortical region might be only

slightly more engaged in one mental function than another, or it might be exclusively engaged in a

single mental function.

“unlike the phrenologists, who believed that very complex traits were associated with discrete brain

regions, modern researchers recognize that […] a single brain region may participate in more than one

function” (Huettel et al., 2004). The fact that a given brain region is consistently involved in the

processing of a specific category of stimuli does not necessarily mean that this brain region is

selectively dedicated to that domain of stimuli. Is the amygdala a “fear module”, i.e., a highly

specialized brain structure for the processing of domain-specific (fear) information?

• The amygdala is not a “fear module”, neither a “negative emotions-dedicated subsystem”

• The amygdala is involved in the processing of biologically relevant stimuli and events (i.e., that can

significantly influence, positively or negatively, an individual’s goals, needs, and well-being), that

include (but are not restricted to), fear-related stimuli. Threatening stimuli are only one type of relevant

stimuli; positive, novel, or ambiguous stimuli can also be relevant

- Fear

Behavioural neuroscientists use the term "fear" or "fear responses" to refer to the combined behavioral

and physiological responses elicited in animals by an overt threat or signal of potential threat. The

behavioral adaptation that allows organism to detect and response to danger. The amygdala responds to

anything that might turn out to have important consequences for safety and for survival (bias toward

false positive responses rather than to false negative ones)

• Thalamo - amygdala route

• Thalamo - cortico - amygdala route

Trasmission may have complementary function trading off speed of transmission against accuracy of

representation mediated by the cortical areas. Destroying one pathway so don't interferes with fear

conditioning, but lesions on two pathways obviously do it. Neither pathway is necessary, each is

sufficient. ( case of G.Y patient : right hemionopia ). [ Case study : patient G.Y. G.Y. is a male patient

who has right hemianopia following damage to his left occipital lobe (V1) at the age of 8 in a car

accident. - Throughout testing, G.Y. denied any perception of faces presented in his blind (right)

hemifield. However, blind hemifield presentation of fearful faces evoked increased responses of the

bilateral amygdala. Also, amygdala responses to fearful and fear-conditioned faces in his blind

hemifield co-varied with activity in the posterior thalamus and superior colliculus : the residual ability

might depend on the colliculo-thalamo-amygdala neural pathway, that can process fear related stimuli

independently of both the striate cortex and visual awareness.]

The role of the amygdala in human fear activation ( central prediction from Le Doux models ):

• Fear stimuli should activate the amygdala

• Amygdala activation should be rapid and not require conscious recognition

• Amygdala activation should be independent of focal attention

• Amygdala activation should not require cortical activation

• The amygdala should be directly activated by visual stimuli via a subcortical route that includes

the superior colliculus of the midbrain and the pulvinar nucleus of the dorsal thalamus.

Activity in the culliculo - thalamo - amygdala route suggest a crude relay of stimulus information, from

the retina to the superior colliculus, which conveys stimulus information to the pulvinar in the posterior

thalamus. The pulvinar is functionally connected with the amygdala, which may facilitate rapid

processing of threat signal. Sich signal may initiate the fight / flight mechanism of the brainsteam

including the locus coeruleus from which noradrenergic pathways are triggered to provide rapid and

diffuse excitatory innervation of the cortex, that facilitates an increare in alertness. Based on the

observation of animal behavioral repertoires, it was proposed that a set of innately determined

defensive behaviors (e.g., freezing and flight) occur in response to all classes of threatening stimuli,

and are orchestrated by a unitary response mechanism for fear. Later, this position was extended to

argue that a unitary brain circuit, with the amygdala as the main switchboard, underlies all types of fear.

In fear conditioning the subject, typically a rat, is placed in an experimental chamber and given paired

presentation of an inn