How to move away from dualism.
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Behavior↗
Biomedical subjects
H Brownell
Publications and source records attributed to H Brownell.
Acquired 'theory of mind' impairments following stroke.
The ability to attribute thoughts and feelings to self and others ('theory of mind') has been hypothesised to have an innate neural basis and a dedicated cognitive mechanism. Evidence in favour of this proposal has come from autism; a brain-based developmental disorder which appears to be characterised by impaired theory of mind, despite sometimes good general reasoning skills/IQ. To date no case of specific acquired theory of mind impairment has been reported. The present study examined theory of mind in adults who had suffered right hemisphere stroke, a group known to show pragmatic and social difficulties. In one study using story materials and two using cartoons, patients' understanding of materials requiring attribution of mental states (e.g. ignorance, false belief) was significantly worse than their understanding of non-mental control materials. Data from healthy elderly subjects, and a small group of left hemisphere patients (who received the tasks in modified form), suggest that this impairment on mental state tasks is not a function of task difficulty. The findings support the notion of a dedicated cognitive system for theory of mind, and suggest a role for the healthy right hemisphere in the attribution of mental states.
Aged↗
Making requests: illustrations of how right-hemisphere brain damage can affect discourse production.
This article examines several factors that influence the production of requests for behavior. Using a role-play methodology, we elicited request productions from well-recovered patients with right-hemisphere brain damage (RHD) and from non brain-damaged control participants. The stimulus items represented variation both on interpersonal factors based on characteristics of the people in the interaction and on situational factors based on what was being requested. A large corpus of responses was elicited from each patient. Responses were coded for request directness, amount of explanatory material over and above the request proper (a relatively demanding method for manipulating the tone of a request), and use of "please" (a relatively simple device for signaling a request). Case-by-case analysis of the patients' performances revealed some common areas of abnormality and also some idiosyncratic features. Some patients produced less explanatory supportive material than control participants, and they tended not to vary the amount of explanatory material as a function of the request scenario. Of interest is that some of the same patients overused "please," and varied their use of this simple device as a function of request scenarios. The discourse strategies observed were likely due to deficits both in pragmatic awareness and in planning utterances. One implication of these results concerns an apt description of the abnormal discourse of RHD patients. The relative lack of supportive explanatory material in their requests may result in patients' seeming rude or inappropriate.
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Distinguishing lies from jokes: theory of mind deficits and discourse interpretation in right hemisphere brain-damaged patients.
Right-hemisphere brain damaged (RHD) patients and a normal control group were tested for their ability to infer first- and second-order mental states and to understand the communicative intentions underlying ironic jokes and lies. Subjects listened to stories involving a character who had either a true or a false belief about another character's knowledge. Stories ended either with an ironic joke or a lie by this character. In the joke stories, the speaker knew that the listener knew the truth (a true second-order belief) and did not expect the listener to believe what was said; in the lie stories, the speaker did not know that the listener actually knew the truth (a false second-order belief) and thus did expect the listener to believe what was said. RHD patients performed significantly worse than control subjects on one of two measures of second-order belief, which suggests that the ability to make second-order mental state attributions is fragile and unreliable following right-hemisphere damage. RHD patients in addition performed worse than controls when asked to distinguish lies from jokes, confirming their known difficulties with discourse interpretation. For both groups, the ability to distinguish lies from jokes was strongly correlated with two measures of the ability to attribute correctly second-order beliefs. These results suggest that the fragility of RHD patients' understanding of second-order mental states underlies a portion of their difficulties in discourse comprehension, but that the underlying impairment is not restricted to right hemisphere dysfunction.
Aged↗
The getting of wisdom: theory of mind in old age.
Theory of mind, the ability to attribute mental states, has been little explored beyond the early school years. Yet, later development, including possible patterns of breakdown, has important implications for current debate concerning the modularity/domain-specificity of the cognitive and neurological systems underlying theory of mind. This article reports a first study of theory of mind in normal aging. The results suggest that although performance on tasks with nonmental content may decrease with age, performance on theory of mind tasks remains intact and may even improve over the later adult years. The implications of these findings for the cognitive processes underlying theory of mind are discussed.
Adolescent↗
Speed of lexical activation in nonfluent Broca's aphasia and fluent Wernicke's aphasia.
Rapid, automatic access to lexical/semantic knowledge is critical in supporting the tight temporal constraints of on-line sentence comprehension. Based on findings of "abnormal" lexical priming in nonfluent aphasics, the question of disrupted automatic lexical activation has been the focus of many recent efforts to understand their impaired sentence comprehension capabilities. The picture that emerges from this literature is, however, unclear. Nonfluent Broca's aphasic patients show inconsistent, not absent, lexical priming, and there is little consensus about the conditions under which they do and do not prime. The most parsimonious explanation for the variable findings from priming studies to date is that the primary disturbance in Broca's lexical activation has something to do with speed of activation. Broca's aphasic patients prime when sufficient time is allowed for activation to spread among associates. To examine this "slowed activation" hypothesis, the time course of lexical activation was examined using a list priming paradigm. Temporal delays between successive words ranged from 300 to 2100 msec. One nonfluent Broca's aphasic patient and one fluent Wernicke's patient were tested. Both patients displayed abnormal priming patterns, though of different sorts. In contrast to elderly subjects, who prime at relatively short interstimulus intervals (ISIs) beginning at 500 msec, the Broca's aphasic subject showed reliable automatic priming but only at a long ISI of 1500 msec. That is, this subject retained the ability to access lexical information automatically if allowed sufficient time to do so, a finding that may help explain disrupted comprehension of normally rapid conversational speech. The Wernicke's aphasic subject, in contrast, showed normally rapid initial activation but continued to show priming over an abnormally long range of delays, from 300 msec through 1100 msec. This protracted priming suggests failure to dampen activation and might explain the semantic confusion exhibited by fluent Wernicke's patients.
Aphasia, Broca↗
The timing of insulin/c-Ras signal is critical for its effect upon the differentiation of C3H10T1/2-derived preadipocytes.
The effect of the peptide hormone insulin upon the differentiation of a 10T1/2-derived preadipocytic line was found to display a potent time-dependence. Insulin addition before cell confluence strongly enhanced differentiation, while addition after confluence had no effect. In keeping with the role of c-Ras as a downstream effector of insulin, c-ras downregulation before confluence abolished differentiation, while it was ineffective once the process of differentiation was underway. These data suggest that the insulin signal is effective during an early window of time before cell confluence, while normal c-Ras levels are required for its transmission.
Adipocytes↗
The effects of right-hemisphere brain damage on patients' use of terms of personal reference.
Successful communication depends on social as well as linguistic factors. In conversation, for example, a speaker must often refer to another person. Choosing an appropriate term of personal reference requires a speaker to consider several features of the discourse context, including properties of the persons being referred to and what knowledge is shared between the speaker and his or her addressee. In a pair of similar studies, we examined how right-hemisphere brain-damaged (RHD) patients and nonbrain-damaged control subjects use these different kinds of information in choosing formal (e.g., "Mr. Harding") versus informal ("Oliver") terms of reference for an absent third person. Stimulus vignettes manipulated three variables: the occupational status of the referent, the speaker's familiarity with the referent (i.e., the degree to which the speaker and referent were personally acquainted), and the addressee's familiarity (i.e., the degree to which the addressee and referent were personally acquainted). Relative to the control subjects, the RHD patients showed decreased use of both familiarity variables when choosing formal over informal labels, but apparently preserved sensitivity to the status variable. These results suggest how decreased use of the knowledge shared between a speaker and addressee disrupts RHD patients' discourse and thus contributes to these patients' aberrant interpersonal behavior. In addition. In addition, the results from the second study demonstrated an asymmetry in how female versus male subjects responded to the status manipulation.
Aged↗
Ras(leu61) blocks differentiation of transformable 3T3 L1 and C3H10T1/2-derived preadipocytes in a dose- and time-dependent manner.
To investigate the functional relationship between the transforming ability of Ras and its role as an integral component of the differentiation-promoting insulin signaling pathway, we introduced a leu61-activated ras gene into the Ras-transformable 3T3 L1 (ATCC CCL92.1) and a number of C3H10T1/2-derived preadipocytic cell lines. The results demonstrate a quantitative reciprocal regulation of differentiation and several transformation-associated properties in response to graded levels of ras gene expression, with the loss of differentiative capacity, morphological transformation, stimulation of proliferation, and anchorage-independent growth requiring increasing levels of Ras(leu61) protein. Furthermore, using novel, tightly regulatable 3T3 L1 transfectants, we demonstrated that Ras(leu61) effectiveness in blocking adipocytic differentiation is strictly dependent on the timing of its expression relative to cell growth arrest, with ras(leu61) expression being ineffective at inhibiting differentiation or inducing morphological transformation once the differentiative process has commenced. Moreover, rasleu61 induction failed to substitute for or enhance the c-Ras-dependent differentiative insulin signal, even under conditions in which it did not induce transformation. Therefore, although necessary for insulin signal transduction, the Ras signal alone is not sufficient to induce adipocytic differentiation in this system. Consistent with its established role as a downstream effector of Ras, v-Raf expression mirrored the Rasleu61 effects on adipocytic differentiation and transformation.
3T3 Cells↗
The allocation of memory resources during sentence comprehension: evidence from the elderly.
Two experiments were carried out to examine the ability of elderly subjects to establish syntactically governed dependency relations during the course of sentence comprehension. The findings reveal the manner in which memory constraints operate during syntactic processing.
Aged↗
Grammatical class effects in relation to normal and aphasic sentence processing.
Agrammatic, Broca's aphasic patients, Wernicke's aphasic patients, and neurologically intact control subjects were asked to detect target letters in prose passages and in a scrambled word passage. The targets were embedded, in some instances, in content words (open-class vocabulary items), and in other instances, in function words (closed-class vocabulary items). With respect to the prose passages, both the control subjects and Wernicke's aphasic patients were more apt to notice target letters when they appeared in the open-class items than when in closed-class items; by contrast, the agrammatic Broca's patients showed no vocabulary class detection difference. The Wernicke's patients were not entirely normal, however: Whereas the normal subjects showed a much smaller vocabulary class effect for letter detection in the scrambled condition, the Wernicke's maintained the pattern they had shown in the prose condition. These and other findings obtained on the letter cancellation task are discussed in relation to lexical access mechanisms geared to sentence parsing.
Adult↗
When preparation fails: disruptive effects of prior information on perceptual recognition.
There is a conflict in the literature on selective attention. Suppose a subject is briefly presented an item followed by a multiple-alternative recognition test. If the items are pictures, the subject's performance is facilitated by presenting the alternatives beforehand (a before facilitation), but when the items are letters the subjects' performance is disrupted by presenting the alternatives beforehand (a before disruption). Five experiments were conducted to resolve this conflict, and all involved a comparison of tachistoscopic recognition when alternatives were either presented beforehand or not. The first two studies showed that the before disruption with letters was not due to certain task parameters. Experiments 3-5 demonstrated that this effect was due to masking conditions. Experiments 3 and 4 revealed that the disruption occurred only when a mask is used, while the last experiment indicated the disruption effect was sensitive to the type of mask employed. Preseumably, the before disrption arises because a subject erroneously considers the features of a mask along with those of the test item in arriving at a perceptual decision.
Attention↗