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Dream recall, brain damage and waking cognitive deficits
184 DREAM RECALL, BRAIN DAMAGE AND WAKING COGNITIVE DEFICITS Fabrizio Doricchi and Cristiano Violani Dipartimento di Psicologia, Universid di Roma, “La Sapienza” Cases of cessation, alteration or maintenance of dreaming following brain damages (BD) of various etiologies, have been occasionally reported in the neuropsychological literature. Some of these reports have been recently reviewed (e.g. Greenberg and Farah, 1986) in order to understand the functional contribution of the two hemispheres to the processes of dream production and recall. The reconsideration of clinical data has been mainly confined by several authors to the issue of the ‘laterality’ of dreaming, disregarding the issue of the lobe-localization of SD and a precise consideration of the waking cognitive deficits concomitant to dream loss. Aiming to a better definition of the contribution of cerebral lobes to the dream experience we reviewed, through an as exhaustive as possible scrutiny of available clinical reports, 168 single cases and 12 studies on groups of BD patients accusing cessation, alteration or maintenance of dreaming reported in the english, french, get-man and italian literature of the last century. Method
Cases lacking sufficient individual clinical information were not considered. For the cases with total cessation of dreaming the frequency distribution analysis (FDA) of the localization of damage (Lobe X Hemisphere) has been repeated in three progressively smaller samples (sample 1: n = 43; sample 2: n = 27; sample 3: n = 22) each excluding a particular sampling bias. A FDA was also applied to the sample of cases with maintenance of dreaming (n = 74). No statistical or symptomatological analysis was attempted on cases with alteration of dreaming due to the small number of cases (n = 9).
laterality of BD is relevant only in the occipital lobes, left and bilateral lesions being more frequent than right ones which are completely absent (s 1: x2,2df, = 10.7, p = 0.005; ~2: ~2, 2df, = 8.40, p = 0.031; ~3: ~2, 2df, = 5.63, p = 0.06). Conversely in the sample of cases with maintenance of dreaming (n = 74) frontal and temporal BD are significantly more frequent 012, 3df, 22.97, p< OOOl), while no difference was shown in the lateral dimension: it must be noted that cases with BD confined to the right occipital were virtually absent (n = 1). Within the sample of single cases with total cessation of dreaming a qualitative-symptomatological analysis of the data evidenced the presence of an highly homogeneous group of anemic-disconnective patients (n = 7) while in the sample of cases of patients with maintenance of dreaming there were two cases with disconnective symptoms but without anomia and a third patient who resumed dreaming in concomitance with the disappearance of anemic-disconnective symptoms (Gloning and Stembach, 1953). All these disconnective patients had a damage confined to the left occipital or inferior occipito-temporal area. In case of left-hemisphere damage both in the sample of single cases and in the studies on groups, loss of dreaming was constantly linked to linguistic-semantic or to visuo-semantic cognitive deficits. Conclusions Our data: a) suggest that integrity of frontal lobes is
not necessary for dreaming; b) point to the existence of a significant link between anemic-disconnective deficits and loss of dreaming; c) show a constant concomitance between posterior linguistic and visuo-semantic deficits and imagery-oneiric deficits; d) are not compatible with the idea of a selective-modular and unilateral-hemispheric functional localization of dream processes; e) given the absence of cases with BD confined to the right occipital lobe, do not allow an evaluation of the functional contribution of this area to dreaming. References
Results
For all samples of patients with cessation of dreaming the FDA has evidenced a significantly minor frequency of BD affecting frontal lobes (sl: x2,1 df, = 8.39, p = 0.004; ~2: ~2, 2 df, = 6.88, p = 0.03; ~3: ~2, 1 df, = 11.63; p= 0.001). For the same samples the
Greenberg, M.S., Farah, M.J. (1986). The laterality of dreaming. Brain and Cognition, 5: 307-321. Gloning, K., Stembach, 1.(1953). ober das traumen bei zerebralen herdlasionen. Wiener Zeitschri~tfiirNerven Heilkunde und Deren Grenzgebiete, 6: 302, 329.
Cases lacking sufficient individual clinical information were not considered. For the cases with total cessation of dreaming the frequency distribution analysis (FDA) of the localization of damage (Lobe X Hemisphere) has been repeated in three progressively smaller samples (sample 1: n = 43; sample 2: n = 27; sample 3: n = 22) each excluding a particular sampling bias. A FDA was also applied to the sample of cases with maintenance of dreaming (n = 74). No statistical or symptomatological analysis was attempted on cases with alteration of dreaming due to the small number of cases (n = 9).
laterality of BD is relevant only in the occipital lobes, left and bilateral lesions being more frequent than right ones which are completely absent (s 1: x2,2df, = 10.7, p = 0.005; ~2: ~2, 2df, = 8.40, p = 0.031; ~3: ~2, 2df, = 5.63, p = 0.06). Conversely in the sample of cases with maintenance of dreaming (n = 74) frontal and temporal BD are significantly more frequent 012, 3df, 22.97, p< OOOl), while no difference was shown in the lateral dimension: it must be noted that cases with BD confined to the right occipital were virtually absent (n = 1). Within the sample of single cases with total cessation of dreaming a qualitative-symptomatological analysis of the data evidenced the presence of an highly homogeneous group of anemic-disconnective patients (n = 7) while in the sample of cases of patients with maintenance of dreaming there were two cases with disconnective symptoms but without anomia and a third patient who resumed dreaming in concomitance with the disappearance of anemic-disconnective symptoms (Gloning and Stembach, 1953). All these disconnective patients had a damage confined to the left occipital or inferior occipito-temporal area. In case of left-hemisphere damage both in the sample of single cases and in the studies on groups, loss of dreaming was constantly linked to linguistic-semantic or to visuo-semantic cognitive deficits. Conclusions Our data: a) suggest that integrity of frontal lobes is
not necessary for dreaming; b) point to the existence of a significant link between anemic-disconnective deficits and loss of dreaming; c) show a constant concomitance between posterior linguistic and visuo-semantic deficits and imagery-oneiric deficits; d) are not compatible with the idea of a selective-modular and unilateral-hemispheric functional localization of dream processes; e) given the absence of cases with BD confined to the right occipital lobe, do not allow an evaluation of the functional contribution of this area to dreaming. References
Results
For all samples of patients with cessation of dreaming the FDA has evidenced a significantly minor frequency of BD affecting frontal lobes (sl: x2,1 df, = 8.39, p = 0.004; ~2: ~2, 2 df, = 6.88, p = 0.03; ~3: ~2, 1 df, = 11.63; p= 0.001). For the same samples the
Greenberg, M.S., Farah, M.J. (1986). The laterality of dreaming. Brain and Cognition, 5: 307-321. Gloning, K., Stembach, 1.(1953). ober das traumen bei zerebralen herdlasionen. Wiener Zeitschri~tfiirNerven Heilkunde und Deren Grenzgebiete, 6: 302, 329.